A thermo-responsive and photo-polymerizable chondroitin sulfate-based hydrogel for 3D printing applications.

Science.gov (United States)

Abbadessa, A; Blokzijl, M M; Mouser, V H M; Marica, P; Malda, J; Hennink, W E; Vermonden, T

2016-09-20

The aim of this study was to design a hydrogel system based on methacrylated chondroitin sulfate (CSMA) and a thermo-sensitive poly(N-(2-hydroxypropyl) methacrylamide-mono/dilactate)-polyethylene glycol triblock copolymer (M15P10) as a suitable material for additive manufacturing of scaffolds. CSMA was synthesized by reaction of chondroitin sulfate with glycidyl methacrylate (GMA) in dimethylsulfoxide at 50°C and its degree of methacrylation was tunable up to 48.5%, by changing reaction time and GMA feed. Unlike polymer solutions composed of CSMA alone (20% w/w), mixtures based on 2% w/w of CSMA and 18% of M15P10 showed strain-softening, thermo-sensitive and shear-thinning properties more pronounced than those found for polymer solutions based on M15P10 alone. Additionally, they displayed a yield stress of 19.2±7.0Pa. The 3D printing of this hydrogel resulted in the generation of constructs with tailorable porosity and good handling properties. Finally, embedded chondrogenic cells remained viable and proliferating over a culture period of 6days. The hydrogel described herein represents a promising biomaterial for cartilage 3D printing applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamic and biocompatible thermo-responsive magnetic hydrogels that respond to an alternating magnetic field

Energy Technology Data Exchange (ETDEWEB)

Crippa, Federica; Moore, Thomas L.; Mortato, Mariangela; Geers, Christoph; Haeni, Laetitia [Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg (Switzerland); Hirt, Ann M. [Institute for Geophysics, ETH Zurich, Sonneggstrasse 5, CH-8092 Zurich (Switzerland); Rothen-Rutishauser, Barbara [Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg (Switzerland); Petri-Fink, Alke, E-mail: alke.fink@unifr.ch [Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg (Switzerland); Chemistry Department, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg Switzerland (Switzerland)

2017-04-01

Magnetic thermo-responsive hydrogels are a new class of materials that have recently attracted interest in biomedicine due to their ability to change phase upon magnetic stimulation. They have been used for drug release, magnetic hyperthermia treatment, and can potentially be engineered as stimuli-responsive substrates for cell mechanobiology. In this regard, we propose a series of magnetic thermo-responsive nanocomposite substrates that undergo cyclical swelling and de-swelling phases when actuated by an alternating magnetic field in aqueous environment. The synthetized substrates are obtained with a facile and reproducible method from poly-N-isopropylacrylamide and superparamagnetic iron oxide nanoparticles. Their conformation and the temperature-related, magnetic, and biological behaviors were characterized via scanning electron microscopy, swelling ratio analysis, vibrating sample magnetometry, alternating magnetic field stimulation and indirect viability assays. The nanocomposites showed no cytotoxicity with fibroblast cells, and exhibited swelling/de-swelling behavior near physiological temperatures (around 34 °C). Therefore these magnetic thermo-responsive hydrogels are promising materials as stimuli-responsive substrates allowing the study of cell-behavior by changing the hydrogel properties in situ. - Highlights: • A magnetic thermo-responsive hydrogel for mechanobiology is proposed. • Hydrogels change phase upon magnetic stimulation near physiological temperature. • Phase changes are reversible and triggered in an aqueous environment. • The hydrogels are biocompatible for murine fibroblast cells.

Influence of Ethylene Glycol Methacrylate to the Hydration and Transition Behaviors of Thermo-Responsive Interpenetrating Polymeric Network Hydrogels

Directory of Open Access Journals (Sweden)

Bing Li

2018-01-01

Full Text Available The influence of ethylene glycol methacrylate (EGMA to the hydration and transition behaviors of thermo-responsive interpenetrating polymeric network (IPN hydrogels containing sodium alginate, N-isopropylacrylamide (NIPAAm, and EGMA were investigated. The molar ratios of NIPAAm and EGMA were varied from 20:0 to 19.5:0.5 and 18.5:1.5 in the thermo-responsive alginate-Ca2+/P(NIPAAm-co-EGMA IPN hydrogels. Due to the more hydrophilicity and high flexibility of EGMA, the IPN hydrogels exhibited higher lower critical solution temperature (LCST and lower glass transition temperature (Tg when the ratio of EGMA increases. The swelling/deswelling kinetics of the IPN hydrogels could be controlled by adjusting the NIPAAm/EGMA molar ratio. A faster water uptake rate and a slower water loss rate could be realized by increase the amount of EGMA in the IPN hydrogel (the shrinking rate constant was decreased from 0.01207 to 0.01195 and 0.01055 with the changing of NIPAAm/EGMA ratio from 20:0, 19.5:0.5 to 18.5:1.5. By using 2-Isopropylthioxanthone (ITX as a photo initiator, the obtained alginate-Ca2+/P(NIPAAm-co-EGMA360 IPN hydrogels were successfully immobilized on cotton fabrics. The surface and cross section of the hydrogel were probed by scanning electron microscopy (SEM. They all exhibited a porous structure, and the pore size was increased with the amount of EGMA. Moreover, the LCST values of the fabric-grafted hydrogels were close to those of the pure IPN hydrogels. Their thermal sensitivity remained unchanged. The cotton fabrics grafted with hydrogel turned out to be much softer with the continuous increase of EGMA amount. Therefore, compared with alginate-Ca2+/PNIPAAm hydrogel, alginate-Ca2+/P(NIPAAm-co-EGMA360 hydrogel is a more promising candidate for wound dressing in the field of biomedical textile.

Dynamic and biocompatible thermo-responsive magnetic hydrogels that respond to an alternating magnetic field

Science.gov (United States)

Crippa, Federica; Moore, Thomas L.; Mortato, Mariangela; Geers, Christoph; Haeni, Laetitia; Hirt, Ann M.; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

2017-04-01

Magnetic thermo-responsive hydrogels are a new class of materials that have recently attracted interest in biomedicine due to their ability to change phase upon magnetic stimulation. They have been used for drug release, magnetic hyperthermia treatment, and can potentially be engineered as stimuli-responsive substrates for cell mechanobiology. In this regard, we propose a series of magnetic thermo-responsive nanocomposite substrates that undergo cyclical swelling and de-swelling phases when actuated by an alternating magnetic field in aqueous environment. The synthetized substrates are obtained with a facile and reproducible method from poly-N-isopropylacrylamide and superparamagnetic iron oxide nanoparticles. Their conformation and the temperature-related, magnetic, and biological behaviors were characterized via scanning electron microscopy, swelling ratio analysis, vibrating sample magnetometry, alternating magnetic field stimulation and indirect viability assays. The nanocomposites showed no cytotoxicity with fibroblast cells, and exhibited swelling/de-swelling behavior near physiological temperatures (around 34 °C). Therefore these magnetic thermo-responsive hydrogels are promising materials as stimuli-responsive substrates allowing the study of cell-behavior by changing the hydrogel properties in situ.

UV-crosslinkable and thermo-responsive chitosan hybrid hydrogel for NIR-triggered localized on-demand drug delivery.

Science.gov (United States)

Wang, Lei; Li, Baoqiang; Xu, Feng; Xu, Zheheng; Wei, Daqing; Feng, Yujie; Wang, Yaming; Jia, Dechang; Zhou, Yu

2017-10-15

Innovative drug delivery technologies based on smart hydrogels for localized on-demand drug delivery had aroused great interest. To acquire smart UV-crosslinkable chitosan hydrogel for NIR-triggered localized on-demanded drug release, a novel UV-crosslinkable and thermo-responsive chitosan was first designed and synthesized by grafting with poly N-isopropylacrylamide, acetylation of methacryloyl groups and embedding with photothermal carbon. The UV-crosslinkable unit (methacryloyl groups) endowed chitosan with gelation via UV irradiation. The thermo-responsive unit (poly N-isopropylacrylamide) endowed chitosan hydrogel with temperature-triggered volume shrinkage and reversible swelling/de-swelling behavior. The chitosan hybrid hydrogel embedded with photothermal carbon exhibited distinct NIR-triggered volume shrinkage (∼42% shrinkage) in response to temperature elevation as induced by NIR laser irradiation. As a demonstration, doxorubicin release rate was accelerated and approximately 40 times higher than that from non-irradiated hydrogels. The UV-crosslinkable and thermal-responsive hybrid hydrogel served as in situ forming hydrogel-based drug depot is developed for NIR-triggered localized on-demand release. Copyright © 2017 Elsevier Ltd. All rights reserved.

Free radical scavenging injectable hydrogels for regenerative therapy

Energy Technology Data Exchange (ETDEWEB)

Komeri, Remya [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Polymer Science Division, BMT Wing, Thiruvananthapuram 695 012, Kerala State (India); Thankam, Finosh Gnanaprakasam [Dept. of Biomedical Sciences, Creighton University, 2500 California Plaza, Omaha NE68178 (United States); Muthu, Jayabalan, E-mail: mjayabalan52@gmail.com [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Polymer Science Division, BMT Wing, Thiruvananthapuram 695 012, Kerala State (India)

2017-02-01

Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07 kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. - Graphical abstract: Injectable hydrogel with inherent free radical scavenging property for regenerative tissue engineering application. - Highlights: • Novel injectable hydrogel (PEAX-P) is prepared using D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer

Free radical scavenging injectable hydrogels for regenerative therapy

International Nuclear Information System (INIS)

Komeri, Remya; Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

2017-01-01

Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07 kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. - Graphical abstract: Injectable hydrogel with inherent free radical scavenging property for regenerative tissue engineering application. - Highlights: • Novel injectable hydrogel (PEAX-P) is prepared using D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer

Carboxylic Terminated Thermo-Responsive Copolymer Hydrogel and Improvement in Peptide Release Profile

Directory of Open Access Journals (Sweden)

Zi-Kun Rao

2018-02-01

Full Text Available To improve the release profile of peptide drugs, thermos-responsive triblock copolymer poly (ε-caprolactone-co-p-dioxanone-b-poly (ethylene glycol-b-poly (ε-caprolactone-co-p-dioxanone (PECP was prepared and end capped by succinic anhydride to give its carboxylic terminated derivative. Both PCEP block copolymer and its end group modified derivative showed temperature-dependent reversible sol-gel transition in water. The carboxylic end group could significantly decrease the sol-gel transition temperature by nearly 10 °C and strengthen the gel due to enhanced intermolecular force among triblock copolymer chains. Furthermore, compared with the original PECP triblock copolymer, HOOC–PECP–COOH copolymer displayed a retarded and sustained release profile for leuprorelin acetate over one month while effectively avoiding the initial burst. The controlled release was believed to be related to the formation of conjugated copolymer-peptide pair by ionic interaction and enhanced solubility of drug molecules into the hydrophobic domains of the hydrogel. Therefore, carboxyl terminated HOOC–PECP–COOH hydrogel was a promising and well-exhibited sustained release carrier for peptide drugs with the advantage of being able to develop injectable formulation by simple mixing.

pH-responsive self-healing injectable hydrogel based on N-carboxyethyl chitosan for hepatocellular carcinoma therapy.

Science.gov (United States)

Qu, Jin; Zhao, Xin; Ma, Peter X; Guo, Baolin

2017-08-01

Injectable hydrogels with pH-responsiveness and self-healing ability have great potential for anti-cancer drug delivery. Herein, we developed a series of polysaccharide-based self-healing hydrogels with pH-sensitivity as drug delivery vehicles for hepatocellular carcinoma therapy. The hydrogels were prepared by using N-carboxyethyl chitosan (CEC) synthesized via Michael reaction in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) (PEGDA). Doxorubicin (Dox), as a model of water-soluble small molecule anti-cancer drug was encapsulated into the hydrogel in situ. Self-healing behavior of the hydrogels was investigated at microscopic and macroscopic levels, and the hydrogels showed rapid self-healing performance without any external stimulus owing to the dynamic covalent Schiff-base linkage between amine groups from CEC and benzaldehyde groups from PEGDA. The chemical structures, rheological property, in vitro gel degradation, morphology, gelation time and in vitro Dox release behavior from the hydrogels were characterized. Injectability was verified by in vitro injection and in vivo subcutaneous injection in a rat. pH-responsive behavior was verified by in vitro Dox release from hydrogels in PBS solutions with different pH values. Furthermore, the activity of Dox released from hydrogel matrix was evaluated by employing human hepatocellular liver carcinoma (HepG2). Cytotoxicity test of the hydrogels using L929 cells confirmed their good cytocompatibility. Together, these pH-responsive self-healing injectable hydrogels are excellent candidates as drug delivery vehicles for liver cancer treatment. STATEMENT OF SIGNIFICANCE: pH-responsive drug delivery system could release drug efficiently in targeted acid environment and minimalize the amount of drug release in normal physiological environment. pH-sensitive injectable hydrogels as smart anti-cancer drug delivery carriers show great potential application for cancer therapy. The hydrogels with self

Thermo-reversible supramolecular hydrogels of trehalose-type diblock methylcellulose analogues.

Science.gov (United States)

Yamagami, Mao; Kamitakahara, Hiroshi; Yoshinaga, Arata; Takano, Toshiyuki

2018-03-01

This paper describes the design and synthesis of new trehalose-type diblock methylcellulose analogues with nonionic, cationic, and anionic cellobiosyl segments, namely 1-(tri-O-methyl-cellulosyl)-4-[β-d-glucopyranosyl-(1→4)-β-d-glucopyranosyloxymethyl]-1H-1,2,3-triazole (1), 1-(tri-O-methyl-cellulosyl)-4-[(6-amino-6-deoxy-β-d-glucopyranosyl)-(1→4)- 6-amino-6-deoxy-β-d-glucopyranosyloxymethyl]-1H-1,2,3-triazole (2), and 4-(tri-O-methyl-cellulosyloxymethyl)-1-[β-d-glucopyranuronosyl-(1→4)-β-d-glucopyranuronosyl]-1H-1,2,3-triazole (3), respectively. Aqueous solutions of all of the 1,2,3-triazole-linked diblock methylcellulose analogues possessed higher surface activities than that of industrially produced methylcellulose and exhibited lower critical solution temperatures, that allowed the formation of thermoresponsive supramolecular hydrogels at close to human body temperature. Supramolecular structures of thermo-reversible hydrogels based on compounds 1, 2, and 3 were investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Detailed structure-property-function relationships of compounds 1, 2, and 3 were discussed. Not only nonionic hydrophilic segment but also ionic hydrophilic segments of diblock methylcellulose analogues were valid for the formation of thermo-reversible supramolecular hydrogels based on end-functionalized methylcellulose. Copyright © 2017 Elsevier Ltd. All rights reserved.

An Injectable Composite Gelatin Hydrogel with pH Response Properties

Directory of Open Access Journals (Sweden)

Baoguo Chen

2017-01-01

Full Text Available On account of minimally invasive procedure and of filling irregular defects of tissues, injectable hydrogels are increasingly attractive in biomedical fields. However, traditional hydrogel formed by simple physical interaction or in situ crosslinking had inevitably some drawbacks such as low mechanical strength and lack of multifunctional properties. Though many investigations had successfully modified traditional injectable hydrogel to obtain both mechanical and functional properties, an acetalated β-cyclodextrin (Ac-β-CD nanoparticle composite injectable hydrogel designed in the research was another effective and efficient choice to solve the drawbacks. First of all, gelatin derivative (G-AA and Ac-β-CD were synthesized to prepare hydrogel and nanoparticle, respectively. In order to ensure good compatibility between nanoparticle and macromonomer and provide crosslink points between nanoparticle and macromonomer, G-AA was simultaneously functionalized onto the surface of Ac-β-CD nanoparticle during the fabrication of Ac-β-CD nanoparticle using one-step method. Finally, injectable composite hydrogel was obtained by photoinitiated polymerization in situ. Hydrogel properties like gelation time and swelling ratio were investigated. The viscoelastic behavior of hydrogels confirmed that typical characteristics of crosslinked elastomer for all hydrogel and nanoparticle in hydrogel could improve the mechanical property of hydrogel. Moreover, the transparency with time had verified obvious acid-response properties of hydrogels.

Artificial phototropism based on a photo-thermo-responsive hydrogel

Science.gov (United States)

Gopalakrishna, Hamsini

Solar energy is leading in renewable energy sources and the aspects surrounding the efforts to harvest light are gaining importance. One such aspect is increasing the light absorption, where heliotropism comes into play. Heliotropism, the ability to track the sun across the sky, can be integrated with solar cells for more efficient photon collection and other optoelectronic systems. Inspired by plants, which optimize incident sunlight in nature, several researchers have made artificial heliotropic and phototropic systems. This project aims to design, synthesize and characterize a material system and evaluate its application in a phototropic system. A gold nanoparticle (Au NP) incorporated poly(N-isopropylacrylamide) (PNIPAAm) hydrogel was synthesized as a photo-thermo-responsive material in our phototropic system. The Au NPs generate heat from the incident via plasmonic resonance to induce a volume phase change of the thermo-responsive hydrogel PNIPAAm. PNIPAAm shrinks or swells at temperature above or below 32°C. Upon irradiation, the Au NP-PNIPAAm micropillar actuates, specifically bending toward the incident light and precisely following the varying incident angle. Swelling ratio tests, bending angle tests with a static incident light and bending tests with varying angles were carried out on hydrogel samples with varying Au NP concentrations. Swelling ratios ranging from 1.45 to 2.9 were recorded for pure hydrogel samples and samples with very low Au NP concentrations. Swelling ratios of 2.41 and 3.37 were calculated for samples with low and high concentrations of Au NPs, respectively. A bending of up to 88° was observed in Au NP-hydrogel pillars with a low Au NP concentration with a 90° incident angle. The light tracking performance was assessed by the slope of the pillar Bending angle (response angle) vs. Incident light angle plot. A slope of 1 indicates ideal tracking with top of the pillar being normal to the incident light, maximizing the photon

Injectable shear-thinning nanoengineered hydrogels for stem cell delivery

DEFF Research Database (Denmark)

Thakur, Ashish; Jaiswal, Manish K.; Peak, Charles W.

2016-01-01

-thinning characteristics, and enhanced mechanical stiffness, elastomeric properties, and physiological stability. The shear-thinning characteristics of nanocomposite hydrogels are investigated for human mesenchymal stem cell (hMSC) delivery. The hMSCs showed high cell viability after injection and encapsulated cells......Injectable hydrogels are investigated for cell encapsulation and delivery as they can shield cells from high shear forces. One of the approaches to obtain injectable hydrogels is to reinforce polymeric networks with high aspect ratio nanoparticles such as two-dimensional (2D) nanomaterials. 2D...... showed a circular morphology. The proposed shear-thinning nanoengineered hydrogels can be used for cell delivery for cartilage tissue regeneration and 3D bioprinting....

Injectable dual redox responsive diselenide-containing poly(ethylene glycol) hydrogel.

Science.gov (United States)

Gong, Chu; Shan, Meng; Li, Bingqiang; Wu, Guolin

2017-09-01

An injectable dual redox responsive diselenide-containing poly(ethylene glycol) (PEG) hydrogel was successfully developed by combining the conceptions of injectable hydrogels and dual redox responsive diselenides. In the first step, four-armed PEG was modified with N-hydroxysuccinimide (NHS)-activated esters and thereafter, crosslinked by selenocystamine crosslinkers to form injectable hydrogels via the rapid reaction between NHS-activated esters and amino groups. The cross-sectional morphology, mechanical properties, and crosslinking modes of hydrogels were well characterized via scanning electron microscope (SEM), rheological measurements, and Fourier transform infrared spectra, respectively. In addition, the oxidation- and reduction-responsive degradation behaviors of hydrogels were observed and analyzed. The model drug, rhodamine B, was encapsulated in the hydrogel. The drug-loaded hydrogel exhibited a dual redox responsive release profile, which was consistent with the degradation experiments. The results of all experiments indicated that the formulated injectable dual redox responsive diselenide-containing PEG hydrogel can have potential applications in various biomedical fields such as drug delivery and stimuli-responsive drug release. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2451-2460, 2017. © 2017 Wiley Periodicals, Inc.

[Construction of injectable tissue engineered nucleus pulposus in vitro].

Science.gov (United States)

Tian, Huake; Wang, Jian; Chen, Chao; Liu, Jie; Zhou, Yue

2009-02-01

To investigate the feasibility of using thermo-sensitive chitosan hydrogen as a scaffold to construct tissue engineered injectable nucleus pulposus (NP). Three-month-old neonatal New Zealand rabbits (male or female) weighing 150-200 g were selected to isolate and culture NP cells. The thermo-sensitive chitosan hydrogel scaffold was made of chitosan, disodium beta-glycerophosphate and hydroxyethyl cellulose. Its physical properties and gross condition were observed. The tissue engineered NP was constructed by compounding the scaffold and rabbit NP cells. Then, the viability of NP cells in the chitosan hydrogel was observed 2 days after compound culture and the growth condition of NP cells on the scaffold was observed by SEM 7 days after compound culture. NP cells went through histology and immunohistochemistry detection and their secretion of aggrecan and expression of Col II mRNA were analyzed by RT-PCR 21 days after compound culture. The thermo-sensitive chitosan hydrogel was liquid at room temperature and solidified into gel at 37 degrees C (15 minutes) due to crosslinking reaction. Acridine orange-propidium iodide staining showed that the viability rate of NP cells in chitosan hydrogel was above 90%. Scanning electron microscope observation demonstrated that the NP cells were distributed in the reticulate scaffold, with ECM on their surfaces. The results of HE, toluidine blue, safranin O and histology and immunohistochemistry staining confirmed that the NP cells in chitosan hydrogel were capable of producing ECM. RT-PCR results showed that the secretion of Col II and aggrecan mRNA in NP cells cultured three-dimensionally by chitosan hydrogen scaffold were 0.631 +/- 0.064 and 0.832 +/- 0.052, respectively, showing more strengths of producing matrix than that of monolayer culture (0.528 +/- 0.039, 0.773 +/- 0.046) with a significant difference (P compound culture, and may be a potential NP cells carrier for tissue engineered NP.

Thermo-sensitive intelligent track membrane

International Nuclear Information System (INIS)

Pang Deling; Ren Lihua; Qian Zhilin; Huang Gang; Zhang Jinhua

1999-01-01

Using N-isopropylacryl-amide (NIP AAm) thermo-sensitive function material as monomer and nuclear track microporous membrane (NTMM) as baseline material, a thermo-sensitive intelligent track membrane (TsITM) has been prepared by the over-oxidization and pre-irradiation grafting techniques. The TsITM can be used to make a micro-switch controlled by temperature and to adjust particle screening and osmosis. To obtain sub-micron responsive grafted track pores only a very thin thermo-sensitive layer is needed. The TsITM pores are capable of swelling and shrinking rapidly and respond more sensitively to temperature

Swelling and Shrinking Properties of Thermo-Responsive Polymeric Ionic Liquid Hydrogels with Embedded Linear pNIPAAM

Directory of Open Access Journals (Sweden)

Simon Gallagher

2014-03-01

Full Text Available In this study, varying concentrations of linear pNIPAAM have been incorporated for the first time into a thermo-responsive polymeric ionic liquid (PIL hydrogel, namely tributyl-hexyl phosphonium 3-sulfopropylacrylate (P-SPA, to produce semi-interpenetrating polymer networks. The thermal properties of the resulting hydrogels have been investigated along with their thermo-induced shrinking and reswelling capabilities. The semi-interpenetrating networks (IPN hydrogels were found to have improved shrinking and reswelling properties compared with their PIL counterpart. At elevated temperatures (50–80 °C, it was found that the semi-IPN with the highest concentration of hydrophobic pNIPAAM exhibited the highest shrinking percentage of ~40% compared to the conventional P-SPA, (27%. This trend was also found to occur for the reswelling measurements, with semi-IPN hydrogels producing the highest reswelling percentage of ~67%, with respect to its contracted state. This was attributed to an increase in water affinity due to the presence of hydrophilic pNIPAAM. Moreover, the presence of linear pNIPAAM in the polymer matrix leads to improved shrinking and reswelling response compared to the equivalent PIL.

Development of injectable hydrogels for nucleus pulposus replacement

Science.gov (United States)

Thomas, Jonathan D.

Intervertebral disc degeneration has been reported as the underlying cause for 75% of cases of lower back pain and is marked by dehydration of the nucleus pulposus within the intervertebral disc. There have been many implant designs to replace the nucleus pulposus. Some researchers have proposed the replacement of the nucleus pulposus with hydrogel materials. The insertion of devices made from these materials further compromises the annulus of the disc. An ideal nucleus replacement could be injected into the disc space and form a solid in vivo. However, injectable replacements using curing elastomers and thermoplastic materials are not ideal because of the potentially harmful exothermic heat evolved from their reactions and the toxicity of the reactants used. We propose a hydrogel system that can be injected as a liquid at 25°C and solidified to yield a hydrogel within the intervertebral disc at 37°C. In aqueous solutions, these polymers have Lower Critical Solution Temperatures (LCST) between 25-37°C, making them unique candidate materials for this application. Poly(N-isopropylacrylamide) (PNIPAAm) is the most widely studied LCST polymer due to its drastic transition near body temperature. However, by itself, pure PNIPAAm forms a hydrogel that has low water content and can readily undergo plastic deformation. To increase the water content and impart elasticity to PNIPAAm hydrogels, grafted and branched hydrogel systems were created that incorporated the thermogelling PNIPAAm and hydrophilic poly(ethylene glycol) (PEG). In this research, the effects of polymer composition and monomer to initiator ratio, which controls polymer MW, on the in vitro swelling properties (mass, chemical, and compressive mechanical stability) of hydrogels formed from aqueous solutions of these polymers were evaluated. Immersion studies were also conducted in solutions to simulate the osmotic environment of the nucleus pulposus. The effects of repeated compression and unloading cycles

Free radical scavenging injectable hydrogels for regenerative therapy.

Science.gov (United States)

Komeri, Remya; Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

2017-02-01

Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

Injectable hydrogels derived from phosphorylated alginic acid calcium complexes

Energy Technology Data Exchange (ETDEWEB)

Kim, Han-Sem; Song, Minsoo, E-mail: minsoosong00@gmail.com; Lee, Eun-Jung; Shin, Ueon Sang, E-mail: usshin12@dankook.ac.kr

2015-06-01

Phosphorylation of sodium alginate salt (NaAlg) was carried out using H{sub 3}PO{sub 4}/P{sub 2}O{sub 5}/Et{sub 3}PO{sub 4} followed by acid–base reaction with Ca(OAc){sub 2} to give phosphorylated alginic acid calcium complexes (CaPAlg), as a water dispersible alginic acid derivative. The modified alginate derivatives including phosphorylated alginic acid (PAlg) and CaPAlg were characterized by nuclear magnetic resonance spectroscopy for {sup 1}H, and {sup 31}P nuclei, high resolution inductively coupled plasma optical emission spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. CaPAlg hydrogels were prepared simply by mixing CaPAlg solution (2 w/v%) with NaAlg solution (2 w/v%) in various ratios (2:8, 4:6, 6:4, 8:2) of volume. No additional calcium salts such as CaSO{sub 4} or CaCl{sub 2} were added externally. The gelation was completed within about 3–40 min indicating a high potential of hydrogel delivery by injection in vivo. Their mechanical properties were tested to be ≤ 6.7 kPa for compressive strength at break and about 8.4 kPa/mm for elastic modulus. SEM analysis of the CaPAlg hydrogels showed highly porous morphology with interconnected pores of width in the range of 100–800 μm. Cell culture results showed that the injectable hydrogels exhibited comparable properties to the pure alginate hydrogel in terms of cytotoxicity and 3D encapsulation of cells for a short time period. The developed injectable hydrogels showed suitable physicochemical and mechanical properties for injection in vivo, and could therefore be beneficial for the field of soft tissue engineering. - Highlights: • Preparation of water-soluble alginic acid complexes with calcium phosphate • Self-assembly of the phosphorylated alginic acid calcium complexes with sodium alginate • Preparation of injectable hydrogels with diverse gelation times within about 3–40 min.

3D- Printed Poly(ε-caprolactone) Scaffold Integrated with Cell-laden Chitosan Hydrogels for Bone Tissue Engineering

OpenAIRE

Dong, Liang; Wang, Shao-Jie; Zhao, Xin-Rong; Zhu, Yu-Fang; Yu, Jia-Kuo

2017-01-01

Synthetic polymeric scaffolds are commonly used in bone tissue engineering (BTE) due to their biocompatibility and adequate mechanical properties. However, their hydrophobicity and the lack of specific cell recognition sites confined their practical application. In this study, to improve the cell seeding efficiency and osteoinductivity, an injectable thermo-sensitive chitosan hydrogel (CSG) was incorporated into a 3D-printed poly(ε-caprolactone) (PCL) scaffold to form a hybrid scaffold. To de...

Injectable Anisotropic Nanocomposite Hydrogels Direct in Situ Growth and Alignment of Myotubes

International Nuclear Information System (INIS)

De France, Kevin J.; Yager, Kevin G.; Chan, Katelyn J. W.; Corbett, Brandon; Cranston, Emily D.; Hoare, Todd

2017-01-01

Here, while injectable in situ cross-linking hydrogels have attracted increasing attention as minimally invasive tissue scaffolds and controlled delivery systems, their inherently disorganized and isotropic network structure limits their utility in engineering oriented biological tissues. Traditional methods to prepare anisotropic hydrogels are not easily translatable to injectable systems given the need for external equipment to direct anisotropic gel fabrication and/or the required use of temperatures or solvents incompatible with biological systems. Herein, we report a new class of injectable nanocomposite hydrogels based on hydrazone cross-linked poly(oligoethylene glycol methacrylate) and magnetically aligned cellulose nanocrystals (CNCs) capable of encapsulating skeletal muscle myoblasts and promoting their differentiation into highly oriented myotubes in situ. CNC alignment occurs on the same time scale as network gelation and remains fixed after the removal of the magnetic field, enabling concurrent CNC orientation and hydrogel injection. The aligned hydrogels show mechanical and swelling profiles that can be rationally modulated by the degree of CNC alignment and can direct myotube alignment both in two- and three-dimensions following coinjection of the myoblasts with the gel precursor components. As such, these hydrogels represent a critical advancement in anisotropic biomimetic scaffolds that can be generated noninvasively in vivo following simple injection.

The effect of glutathione as chain transfer agent in PNIPAAm-based thermo-responsive hydrogels for controlled release of proteins.

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Drapala, Pawel W; Jiang, Bin; Chiu, Yu-Chieh; Mieler, William F; Brey, Eric M; Kang-Mieler, Jennifer J; Pérez-Luna, Victor H

2014-03-01

To control degradation and protein release using thermo-responsive hydrogels for localized delivery of anti-angiogenic proteins. Thermo-responsive hydrogels derived from N-isopropylacrylamide (NIPAAm) and crosslinked with poly(ethylene glycol)-co-(L-lactic acid) diacrylate (Acry-PLLA-b-PEG-b-PLLA-Acry) were synthesized via free radical polymerization in the presence of glutathione, a chain transfer agent (CTA) added to modulate their degradation and release properties. Immunoglobulin G (IgG) and the recombinant proteins Avastin® and Lucentis® were encapsulated in these hydrogels and their release was studied. The encapsulation efficiency of IgG was high (75-87%) and decreased with CTA concentration. The transition temperature of these hydrogels was below physiological temperature, which is important for minimally invasive therapies involving these materials. The toxicity from unreacted monomers and free radical initiators was eliminated with a minimum of three buffer extractions. Addition of CTA accelerated degradation and resulted in complete protein release. Glutathione caused the degradation products to become solubilized even at 37°C. Hydrogels prepared without glutathione did not disintegrate nor released protein completely after 3 weeks at 37°C. PEGylation of IgG postponed the burst release effect. Avastin® and Lucentis® released from degraded hydrogels retained their biological activity. These systems offer a promising platform for the localized delivery of proteins.

Self-cleaned electrochemical protein imprinting biosensor basing on a thermo-responsive memory hydrogel.

Science.gov (United States)

Wei, Yubo; Zeng, Qiang; Hu, Qiong; Wang, Min; Tao, Jia; Wang, Lishi

2018-01-15

Herein, the self-cleaned electrochemical protein imprinting biosensor basing on a thermo-responsive memory hydrogel was constructed on a glassy carbon electrode (GCE) with a free radical polymerization method. Combining the advantages of thermo-responsive molecular imprinted polymers and electrochemistry, the resulted biosensor presents a novel self-cleaned ability for bovine serum albumin (BSA) in aqueous media. As a temperature controlled gate, the hydrogel film undergoes the adsorption and desorption of BSA basing on a reversible structure change with the external temperature stimuli. In particular, these processes have been revealed by the response of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) of electroactive [Fe(CN) 6 ] 3-/4- . The results have been supported by the evidences of scanning electron microscopy (SEM) and contact angles measurements. Under the optimal conditions, a wide detection range from 0.02μmolL -1 to 10μmolL -1 with a detection limit of 0.012 μmolL -1 (S/N = 3) was obtained for BSA. This proposed BSA sensor also possesses high selectivity, excellent stability, acceptable recovery and good reproducibility in its practical applications. Copyright © 2017. Published by Elsevier B.V.

Injectable hydrogels for central nervous system therapy

International Nuclear Information System (INIS)

Pakulska, Malgosia M; Shoichet, Molly S; Ballios, Brian G

2012-01-01

Diseases and injuries of the central nervous system (CNS) including those in the brain, spinal cord and retina are devastating because the CNS has limited intrinsic regenerative capacity and currently available therapies are unable to provide significant functional recovery. Several promising therapies have been identified with the goal of restoring at least some of this lost function and include neuroprotective agents to stop or slow cellular degeneration, neurotrophic factors to stimulate cellular growth, neutralizing molecules to overcome the inhibitory environment at the site of injury, and stem cell transplant strategies to replace lost tissue. The delivery of these therapies to the CNS is a challenge because the blood–brain barrier limits the diffusion of molecules into the brain by traditional oral or intravenous routes. Injectable hydrogels have the capacity to overcome the challenges associated with drug delivery to the CNS, by providing a minimally invasive, localized, void-filling platform for therapeutic use. Small molecule or protein drugs can be distributed throughout the hydrogel which then acts as a depot for their sustained release at the injury site. For cell delivery, the hydrogel can reduce cell aggregation and provide an adhesive matrix for improved cell survival and integration. Additionally, by choosing a biodegradable or bioresorbable hydrogel material, the system will eventually be eliminated from the body. This review discusses both natural and synthetic injectable hydrogel materials that have been used for drug or cell delivery to the CNS including hyaluronan, methylcellulose, chitosan, poly(N-isopropylacrylamide) and Matrigel. (paper)

Injectable self-healing carboxymethyl chitosan-zinc supramolecular hydrogels and their antibacterial activity.

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Wahid, Fazli; Zhou, Ya-Ning; Wang, Hai-Song; Wan, Tong; Zhong, Cheng; Chu, Li-Qiang

2018-04-07

Injectable and self-healing hydrogels have found numerous applications in drug delivery, tissue engineering and 3D cell culture. Herein, we report an injectable self-healing carboxymethyl chitosan (CMCh) supramolecular hydrogels cross-linked by zinc ions (Zn 2+ ). Supramolecular hydrogels were obtained by simple addition of metal ions solution to CMCh solution at an appropriate pH value. The mechanical properties of these hydrogels were adjustable by the concentration of Zn 2+ . For example, the hydrogel with the highest concentration of Zn 2+ (CMCh-Zn4) showed strongest mechanical properties (storage modulus~11,000Pa) while hydrogel with the lowest concentration of Zn 2+ (CMCh-Zn1) showed weakest mechanical properties (storage modulus~220Pa). As observed visually and confirmed rheologically, the CMCh-Zn1 hydrogel with the lowest Zn 2+ concentration showed thixotropic property. CMCh-Zn1 hydrogel also presented injectable property. Moreover, the antibacterial properties of the prepared supramolecular hydrogels were studied against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) by agar well diffusion method. The results revealed Zn 2+ dependent antibacterial properties against both kinds of strains. The inhibition zones were ranging from ~11-24mm and ~10-22mm against S. aureus and E. coli, respectively. We believe that the prepared supramolecular hydrogels could be used as a potential candidate in biomedical fields. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis and Characterization of pH and Thermo Dual-Responsive Hydrogels with a Semi-IPN Structure Based on N-Isopropylacrylamide and Itaconamic Acid.

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Rwei, Syang-Peng; Tuan, Huynh Nguyen Anh; Chiang, Whe-Yi; Way, Tun-Fun

2018-04-28

A series of semi-interpenetrating polymer network (semi-IPN) hydrogels were synthesized and investigated in this study. Linear copolymer poly( N -isopropylacrylamide-co-itaconamic acid) p(NIPAM-co-IAM), which is formed by copolymerization of N -isopropylacrylamide (NIPAM) and itaconamic acid (IAM, 4-amino-2-ethylene-4-oxobutanoic acid), was introduced into a solution of NIPAM to form a series of pH and thermo dual-responsive p(NIPAM-co-IAM)/pNIPAM semi-IPN hydrogels by free radical polymerization. The structural, morphological, chemical, and physical properties of the linear copolymer and semi-IPN hydrogels were investigated. The semi-IPN hydrogel showed high thermal stability according to thermal gravimetric analyzer (TGA). Scanning electronic microscopy (SEM) images showed that the pore size was in the range of 119~297 µm and could be controlled by the addition ratio of the linear copolymer in the semi-IPN structure. The addition of linear copolymer increased the fracture strain from 57.5 ± 2.9% to 91.1 ± 4.9% depending on the added amount, while the compressive modulus decreased as the addition increased. Moreover, the pH and thermo dual-responsive properties were investigated using differential scanning calorimetry (DSC) and monitoring the swelling behavior of the hydrogels. In deionized (DI) water, the equilibrium swelling ratio of the hydrogels decreased as the temperature increased from 20 °C to 50 °C, while it varied in various pH buffer solutions. In addition, the swelling and deswelling rates of the hydrogels also significantly increased. The results indicate that the novel pH-thermo dual-responsive semi-IPN hydrogels were synthesized successfully and may be a potential material for biomedical, drug delivery, or absorption application.

An Injectable Enzymatically Crosslinked Carboxymethylated Pullulan/Chondroitin Sulfate Hydrogel for Cartilage Tissue Engineering

Science.gov (United States)

Chen, Feng; Yu, Songrui; Liu, Bing; Ni, Yunzhou; Yu, Chunyang; Su, Yue; Zhu, Xinyuan; Yu, Xiaowei; Zhou, Yongfeng; Yan, Deyue

2016-01-01

In this study, an enzymatically cross-linked injectable and biodegradable hydrogel system comprising carboxymethyl pullulan-tyramine (CMP-TA) and chondroitin sulfate-tyramine (CS-TA) conjugates was successfully developed under physiological conditions in the presence of both horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) for cartilage tissue engineering (CTTE). The HRP crosslinking method makes this injectable system feasible, minimally invasive and easily translatable for regenerative medicine applications. The physicochemical properties of the mechanically stable hydrogel system can be modulated by varying the weight ratio and concentration of polymer as well as the concentrations of crosslinking reagents. Additionally, the cellular behaviour of porcine auricular chondrocytes encapsulated into CMP-TA/CS-TA hydrogels demonstrates that the hydrogel system has a good cyto-compatibility. Specifically, compared to the CMP-TA hydrogel, these CMP-TA/CS-TA composite hydrogels have enhanced cell proliferation and increased cartilaginous ECM deposition, which significantly facilitate chondrogenesis. Furthermore, histological analysis indicates that the hydrogel system exhibits acceptable tissue compatibility by using a mouse subcutaneous implantation model. Overall, the novel injectable pullulan/chondroitin sulfate composite hydrogels presented here are expected to be useful biomaterial scaffold for regenerating cartilage tissue.

Injectable, Biomolecule-Responsive Polypeptide Hydrogels for Cell Encapsulation and Facile Cell Recovery through Triggered Degradation.

Science.gov (United States)

Xu, Qinghua; He, Chaoliang; Zhang, Zhen; Ren, Kaixuan; Chen, Xuesi

2016-11-16

Injectable hydrogels have been widely investigated in biomedical applications, and increasing demand has been proposed to achieve dynamic regulation of physiological properties of hydrogels. Herein, a new type of injectable and biomolecule-responsive hydrogel based on poly(l-glutamic acid) (PLG) grafted with disulfide bond-modified phloretic acid (denoted as PLG-g-CPA) was developed. The hydrogels formed in situ via enzymatic cross-linking under physiological conditions in the presence of horseradish peroxidase and hydrogen peroxide. The physiochemical properties of the hydrogels, including gelation time and the rheological property, were measured. Particularly, the triggered degradation of the hydrogel in response to a reductive biomolecule, glutathione (GSH), was investigated in detail. The mechanical strength and inner porous structure of the hydrogel were influenced by the addition of GSH. The polypeptide hydrogel was used as a three-dimensional (3D) platform for cell encapsulation, which could release the cells through triggered disruption of the hydrogel in response to the addition of GSH. The cells released from the hydrogel were found to maintain high viability. Moreover, after subcutaneous injection into rats, the PLG-g-CPA hydrogels with disulfide-containing cross-links exhibited a markedly faster degradation behavior in vivo compared to that of the PLG hydrogels without disulfide cross-links, implying an interesting accelerated degradation process of the disulfide-containing polypeptide hydrogels in the physiological environment in vivo. Overall, the injectable and biomolecule-responsive polypeptide hydrogels may serve as a potential platform for 3D cell culture and easy cell collection.

Microfluidics-assisted generation of stimuli-responsive hydrogels based on alginates incorporated with thermo-responsive and amphiphilic polymers as novel biomaterials.

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Karakasyan, C; Mathos, J; Lack, S; Davy, J; Marquis, M; Renard, D

2015-11-01

We used a droplet-based microfluidics technique to produce monodisperse responsive alginate-block-polyetheramine copolymer microgels. The polyetheramine group (PEA), corresponding to a propylene oxide /ethylene oxide ratio (PO/EO) of 29/6 (Jeffamine(®) M2005), was condensed, via the amine link, to alginates with various mannuronic/guluronic acids ratios and using two alginate:jeffamine mass ratios. The size of the grafted-alginate microgels varied from 60 to 80 μm depending on the type of alginate used and the degree of substitution. The droplet-based microfluidics technique offered exquisite control of both the dimension and physical chemical properties of the grafted-alginate microgels. These microgels were therefore comparable to isolated grafted-alginate chains in retaining both their amphiphilic and thermo-sensitive properties. Amphiphilicity was demonstrated at the oil-water interface where grafted-alginate microgels were found to decrease interfacial tension by ∼ 50%. The thermo-sensitivity of microgels was clearly demonstrated and a 10 to 20% reduction in size between was evidenced on increasing the temperature above the lower critical solution temperature (TLCST) of Jeffamine. In addition, the reversibility of thermo-sensitivity was demonstrated by studying the oil-water affinity of microgels with temperature after Congo red labeling. Finally, droplet-based microfluidics was found to be a good and promising tool for generating responsive biobased hydrogels for drug delivery applications and potential new colloidal stabilizers for dispersed systems such as Pickering emulsions. Copyright © 2015 Elsevier B.V. All rights reserved.

Intratumoral Delivery of Doxorubicin on Folate-Conjugated Graphene Oxide by In-Situ Forming Thermo-Sensitive Hydrogel for Breast Cancer Therapy

Directory of Open Access Journals (Sweden)

Yi Teng Fong

2017-11-01

Full Text Available By taking advantage of the pH-sensitive drug release property of graphene oxide (GO after intracellular uptake, we prepared folic acid (FA-conjugated GO (GOFA for targeted delivery of the chemotherapeutic drug doxorubicin (DOX. GOFA-DOX was further encapsulated in an injectable in-situ forming thermo-sensitive hyaluronic acid-chitosan-g-poly(N-isopropylacrylamide (HACPN hydrogel for intratumoral delivery of DOX. As the degradation time of HACPN could be extended up to 3 weeks, intratumoral delivery of GOFA-DOX/HACPN could provide controlled and targeted delivery of DOX through slow degradation HACPN and subsequent cellular uptake of released GOFA-DOX by tumor cells through interactions of GOFA with folate receptors on the tumor cell’s surface. GOFA nano-carrier and HACPN hydrogel were first characterized for the physico-chemical properties. The drug loading experiments indicated the best preparation condition of GOFA-DOX was by reacting 0.1 mg GOFA with 2 mg DOX. GOFA-DOX showed pH-responsive drug release with ~5 times more DOX released at pH 5.5 than at pH 7.4 while only limited DOX was released from GOFA-DOX/HACPN at pH 7.4. Intracellular uptake of GOFA by endocytosis and release of DOX from GOFA-DOX in vitro could be confirmed from transmission electron microscopic and confocal laser scanning microscopic analysis with MCF-7 breast cancer cells. The targeting effect of FA was revealed when intracellular uptake of GOFA was blocked by excess FA. This resulted in enhanced in vitro cytotoxicity as revealed from the lower half maximal inhibitory concentration (IC50 value of GOFA-DOX (7.3 μg/mL compared with that of DOX (32.5 μg/mL and GO-DOX (10 μg/mL. The flow cytometry analysis indicated higher apoptosis rates for cells treated with GOFA-DOX (30% compared with DOX (8% and GO-DOX (11%. Animal studies were carried out with subcutaneously implanted MCF-7 cells in BALB/c nude mice and subject to intratumoral administration of drugs. The relative

Preparation of Chitosan-based Injectable Hydrogels and Its Application in 3D Cell Culture.

Science.gov (United States)

Li, Yongsan; Zhang, Yaling; Wei, Yen; Tao, Lei

2017-09-29

The protocol presents a facile, efficient, and versatile method to prepare chitosan-based hydrogels using dynamic imine chemistry. The hydrogel is prepared by mixing solutions of glycol chitosan with a synthesized benzaldehyde terminated polymer gelator, and hydrogels are efficiently obtained in several minutes at room temperature. By varying ratios between glycol chitosan, polymer gelator, and water contents, versatile hydrogels with different gelation times and stiffness are obtained. When damaged, the hydrogel can recover its appearances and modulus, due to the reversibility of the dynamic imine bonds as crosslinkages. This self-healable property enables the hydrogel to be injectable since it can be self-healed from squeezed pieces to an integral bulk hydrogel after the injection process. The hydrogel is also multi-responsive to many bio-active stimuli due to different equilibration statuses of the dynamic imine bonds. This hydrogel was confirmed as bio-compatible, and L929 mouse fibroblast cells were embedded following standard procedures and the cell proliferation was easily assessed by a 3D cell cultivation process. The hydrogel can offer an adjustable platform for different research where a physiological mimic of a 3D environment for cells is profited. Along with its multi-responsive, self-healable, and injectable properties, the hydrogels can potentially be applied as multiple carriers for drugs and cells in future bio-medical applications.

Injectable dextran hydrogels fabricated by metal-free click chemistry for cartilage tissue engineering.

Science.gov (United States)

Wang, Xiaoyu; Li, Zihan; Shi, Ting; Zhao, Peng; An, Kangkang; Lin, Chao; Liu, Hongwei

2017-04-01

Injectable dextran-based hydrogels were prepared for the first time by bioorthogonal click chemistry for cartilage tissue engineering. Click-crosslinked injectable hydrogels based on cyto-compatible dextran (Mw=10kDa) were successfully fabricated under physiological conditions by metal-free alkyne-azide cycloaddition (click) reaction between azadibenzocyclooctyne-modified dextran (Dex-ADIBO) and azide-modified dextran (Dex-N 3 ). Gelation time of these dextran hydrogels could be regulated in the range of approximately 1.1 to 10.2min, depending on the polymer concentrations (5% or 10%) and ADIBO substitution degree (DS, 5 or 10) of Dex-ADIBO. Rheological analysis indicated that the dextran hydrogels were elastic and had storage moduli from 2.1 to 6.0kPa with increasing DS of ADIBO from 5 to 10. The in vitro tests revealed that the dextran hydrogel crosslinked from Dex-ADIBO DS 10 and Dex-N 3 DS 10 at a polymer concentration of 10% could support high viability of individual rabbit chondrocytes and the chondrocyte spheroids encapsulated in the hydrogel over 21days. Individual chondrocytes and chondrocyte spheroids in the hydrogel could produce cartilage matrices such as collagen and glycosaminoglycans. However, the chondrocyte spheroids produced a higher content of matrices than individual chondrocytes. This study indicates that metal-free click chemistry is effective to produce injectable dextran hydrogels for cartilage tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

Construction of Injectable Double-Network Hydrogels for Cell Delivery.

Science.gov (United States)

Yan, Yan; Li, Mengnan; Yang, Di; Wang, Qian; Liang, Fuxin; Qu, Xiaozhong; Qiu, Dong; Yang, Zhenzhong

2017-07-10

Herein we present a unique method of using dynamic cross-links, which are dynamic covalent bonding and ionic interaction, for the construction of injectable double-network (DN) hydrogels, with the objective of cell delivery for cartilage repair. Glycol chitosan and dibenzaldhyde capped poly(ethylene oxide) formed the first network, while calcium alginate formed the second one, and in the resultant DN hydrogel, either of the networks could be selectively removed. The moduli of the DN hydrogel were significantly improved compared to that of the parent single-network hydrogels and were tunable by changing the chemical components. In situ 3D cell encapsulation could be easily performed by mixing cell suspension to the polymer solutions and transferred through a syringe needle before sol-gel transition. Cell proliferation and mediated differentiation of mouse chondrogenic cells were achieved in the DN hydrogel extracellular matrix.

pH-Sensitive Hydrogel for Micro-Fluidic Valve

Directory of Open Access Journals (Sweden)

Zhengzhi Yang

2012-07-01

Full Text Available The deformation behavior of a pH-sensitive hydrogel micro-fluidic valve system is investigated using inhomogeneous gel deformation theory, in which the fluid-structure interaction (FSI of the gel solid and fluid flow in the pipe is considered. We use a finite element method with a well adopted hydrogel constitutive equation, which is coded in commercial software, ABAQUS, to simulate the hydrogel valve swelling deformation, while FLUENT is adopted to model the fluid flow in the pipe of the hydrogel valve system. The study demonstrates that FSI significantly affects the gel swelling deformed shapes, fluid flow pressure and velocity patterns. FSI has to be considered in the study on fluid flow regulated by hydrogel microfluidic valve. The study provides a more accurate and adoptable model for future design of new pH-sensitive hydrogel valves, and also gives a useful guideline for further studies on hydrogel fluidic applications.

Thermo-sensitive and swelling properties of cellouronic acid sodium/poly (acrylamide-co-diallyldimethylammonium chloride) semi-IPN.

Science.gov (United States)

Zhang, Heng; Gao, Xin; Chen, Keli; Li, Hui; Peng, Lincai

2018-02-01

In current study, cellouronic acid sodium (CAS), obtained from bagasse pith, has been introduced into poly(acrylamide-co-diallyldimethylammonium chloride) (poly(AM-co-DAC)) network to form novel thermo-sensitive semi-IPNs. The structure and morphology of the hydrogels were proved by Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effects of CAS content, initiator charge, cross-linker dosage and swelling-medium property on the thermo-responsive water absorptivity were investigated in detail. The results elucidated that the prepared gels exhibited a thermo-sensibility with an upper critical solution temperature (UCST) and a high water-absorbency. And the values of UCST and equilibrium swelling ratio largely depended on the inner structure of the semi-IPNs and the external solvent property. It was also revealed that the swelling process conformed to the Schott's pseudo second order model and diffusion type was non-Fickian diffusion. The value of activation energy for this polyelectrolyte was found to be 8.74kJ/mol. Copyright © 2017 Elsevier Ltd. All rights reserved.

Self-Healing and Thermo-Responsive Dual-Crosslinked Alginate Hydrogels based on Supramolecular Inclusion Complexes

Science.gov (United States)

Miao, Tianxin; Fenn, Spencer L.; Charron, Patrick N.; Oldinski, Rachael A.

2015-01-01

β-cyclodextrin (β-CD), with a lipophilic inner cavity and hydrophilic outer surface, interacts with a large variety of non-polar guest molecules to form non-covalent inclusion complexes. Conjugation of β-CD onto biomacromolecules can form physically-crosslinked hydrogel networks upon mixing with a guest molecule. Herein describes the development and characterization of self-healing, thermo-responsive hydrogels, based on host-guest inclusion complexes between alginate-graft-β-CD and Pluronic® F108 (poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol)). The mechanics, flow characteristics, and thermal response were contingent on the polymer concentrations, and the host-guest molar ratio. Transient and reversible physical crosslinking between host and guest polymers governed self-assembly, allowing flow under shear stress, and facilitating complete recovery of the material properties within a few seconds of unloading. The mechanical properties of the dual-crosslinked, multi-stimuli responsive hydrogels were tuned as high as 30 kPa at body temperature, and are advantageous for biomedical applications such as drug delivery and cell transplantation. PMID:26509214

Thixotropic injectable hydrogel using a polyampholyte and nanosilicate prepared directly after cryopreservation

Energy Technology Data Exchange (ETDEWEB)

Jain, Minkle; Matsumura, Kazuaki, E-mail: mkazuaki@jaist.ac.jp

2016-12-01

Success of tissue engineering applications in regenerative medicine requires the preservation of tissue-engineered products at a low temperature. This can be successfully achieved by the use of cryoprotective agent (CPA). In this study, we formulated a unique injectable hydrogel for the purpose of cell delivery after cryopreservation by using polyampholyte CPA. The polyampholyte showed excellent post-thaw cell survival, and after thawing, the polymeric CPA did not have to be removed because of its low cytotoxicity. The polyampholyte could be transformed into a hydrogel by mixing with nanosilicates. Previously, nanosilicates were used to improve mechanical properties, but this is the first report of the use of a nanosilicate together with CPA to formulate hydrogels. Inclusion of the nanosilicate led to the formation of thixotropic hydrogels, which can be injected using fine needles. These gels with tunable mechanical properties can be injected into defect sites to form scaffolds for cell growth and tissue repair, and they do not require any separate seeding of cells before injection, thus eliminating the need for cell harvesting and cell maintenance. This is a distinct system in which cells can be cryopreserved until before usage; when required, the cells in the polyampholyte can be revived to their original state and the thixotropic hydrogel can be formed. The combination of thixotropy and cytocompatibility of the gels could enable a wide range of biomedical applications such as cell delivery and orthopedic repair. - Graphical abstract: A novel thixotropic, cytocompatible and injectable nanocomposite hydrogel with tunable mechanical properties directly after cryopreservation was formulated using an efficient polymer cryoprotectant and laponite. This is an efficient system in which cells remain viable and can proliferate even after one week. The combined use of thixotropy and cytocompatibility enables this system to be used for cell delivery applications

Analgesic Effect of Intra-Articular Injection of Temperature-Responsive Hydrogel Containing Bupivacaine on Osteoarthritic Pain in Rats

Science.gov (United States)

Kim, Taemin; Seol, Dong Rim; Hahm, Suk-Chan; Ko, Cheolwoong; Kim, Eun-Hye; Chun, Keyoungjin; Kim, Junesun; Lim, Tae-Hong

2015-01-01

The present study examined the analgesic effects of slow-releasing bupivacaine from hydrogel on chronic arthritic pain in rats. Osteoarthritis (OA) was induced by monosodium iodoacetate (MIA) injection into the right knee joint. Hydrogel (HG: 20, 30, and 50 μL) and temperature-sensitive hydrogel containing bupivacaine (T-gel: 20, 30, and 50 μL) were injected intra-articularly 14 days after MIA injection. Behavioral tests were conducted. The rats showed a significant decrease in weight load and paw withdrawal threshold (PWT). Intra-articular 0.5% bupivacaine (10 and 20 μL) significantly reversed MIA-induced decreased PWT, with no effect on weight load. In normal rats, hydrogel did not produce significant changes in PWT but at 30 and 50 μL slightly decreased weight bearing; T-gel did not cause any changes in both the weight load and PWT. In OA rats, T-gel at 20 μL had a significant analgesic effect for 2 days, even though T-gel at 50 μL further reduced the weight load, demonstrating that intra-articular T-gel (20 μL) has long-lasting analgesic effects in OA rats. Thus, T-gel designed to deliver analgesics into the joint cavity could be an effective therapeutic tool in the clinical setting. PMID:26881207

MRI diagnosis of the complications of polyamide hydrogel injection for augmentation mammoplasty

International Nuclear Information System (INIS)

Chen Xueqiang; Chen Pingyou; Zhang Yunshu; Luo Qinghua; Xu Rong

2005-01-01

Objective: To analyze MRI findings and its clinical significance in complications of polyamide hydrogel injection for augmentation mammoplasty. Methods: The complication findings of MR imaging in 20 cases with polyamide hydrogel injection for augmentation mammoplasty were retrospectively reviewed and analyzed. Results: In 20 patients, 26 breasts suffered from complications, including infection (n=5) with pieces of long T 1 and long T 2 signals, aseptic inflammation (n=2) with pieces of slight long T 1 and moderate T 2 signals, hard nodule (n=10) with long T 1 and long T 2 signals, and rupture (n=5) with pieces and nodes of long T 1 and long T 2 signals on MR images. Conclusion: MRI has the great diagnostic value in the detection of complications after polyamide hydrogel injection for augmentation mammoplasty, and it should be taken as the first diagnostic choice. (authors)

Injectable alginate-O-carboxymethyl chitosan/nano fibrin composite hydrogels for adipose tissue engineering.

Science.gov (United States)

Jaikumar, Dhanya; Sajesh, K M; Soumya, S; Nimal, T R; Chennazhi, K P; Nair, Shantikumar V; Jayakumar, R

2015-03-01

Injectable, biodegradable scaffolds are required for soft tissue reconstruction owing to its minimally invasive approach. Such a scaffold can mimic the native extracellular matrix (ECM), provide uniform distribution of cells and overcome limitations like donor site morbidity, volume loss, etc. So, here we report two classes of biocompatible and biodegradable hydrogel blend systems namely, Alginate/O-carboxymethyl chitosan (O-CMC) and Alginate/poly (vinyl alcohol) (PVA) with the inclusion of fibrin nanoparticles in each. The hydrogels were prepared by ionic cross-linking method. The developed hydrogels were compared in terms of its swelling ratio, degradation profile, compressive strength and elastic moduli. From these preliminary findings, it was concluded that Alginate/O-CMC formed a better blend for tissue engineering applications. The potential of the formed hydrogel as an injectable scaffold was revealed by the survival of adipose derived stem cells (ADSCs) on the scaffold by its adhesion, proliferation and differentiation into adipocytes. Cell differentiation studies of fibrin incorporated hydrogel scaffolds showed better differentiation was confirmed by Oil Red O staining technique. These injectable gels have potential in soft tissue regeneration. Copyright © 2014 Elsevier B.V. All rights reserved.

Bioinspired Smart Actuator Based on Graphene Oxide-Polymer Hybrid Hydrogels.

Science.gov (United States)

Wang, Tao; Huang, Jiahe; Yang, Yiqing; Zhang, Enzhong; Sun, Weixiang; Tong, Zhen

2015-10-28

Rapid response and strong mechanical properties are desired for smart materials used in soft actuators. A bioinspired hybrid hydrogel actuator was designed and prepared by series combination of three trunks of tough polymer-clay hydrogels to accomplish the comprehensive actuation of "extension-grasp-retraction" like a fishing rod. The hydrogels with thermo-creep and thermo-shrinking features were successively irradiated by near-infrared (NIR) to execute extension and retraction, respectively. The GO in the hydrogels absorbed the NIR energy and transformed it into thermo-energy rapidly and effectively. The hydrogel with adhesion or magnetic force was adopted as the "hook" of the hybrid hydrogel actuator for grasping object. The hook of the hybrid hydrogel actuator was replaceable according to applications, even with functional materials other than hydrogels. This study provides an innovative concept to explore new soft actuators through combining response hydrogels and programming the same stimulus.

Dual Salt- and Thermo-Responsive Programmable Bilayer Hydrogel Actuators with Pseudo-Interpenetrating Double-Network Structures.

Science.gov (United States)

Xiao, Shengwei; Zhang, Mingzhen; He, Xiaomin; Huang, Lei; Zhang, Yanxian; Ren, Baiping; Zhong, Mingqiang; Chang, Yung; Yang, Jintao; Zheng, Jie

2018-06-07

Development of smart soft actuators is highly important for fundamental research and industrial applications, but has proved to be extremely challenging. In this work, we present a facile, one-pot, one-step method to prepare dual-responsive bilayer hydrogels, consisting of a thermos-responsive poly(N-isopropyl acrylamide) (polyNIPAM) layer and a salt-responsive poly(3-(1-(4-vinylbenzyl)-1H-imidazol-3-ium-3-yl)propane-1-sulfonat) (polyVBIPS) layer. Both polyNIPAM and polyVBIPs layers exhibit a completely opposite swelling/shrinking behavior, where polyNIPAM shrinks (swells) but polyVBIPS swells (shrinks) in salt solution (water) or at high (low) temperatures. By tuning NIPAM:VBIPS ratios, the resulting polyNIPAM/polyVBIPS bilayer hydrogels enable to achieve fast and large-amplitude bidirectional bending in response to temperatures, salt concentrations, and salt types. Such bidirectional bending, bending orientation and degree can be reversibly, repeatedly, and precisely controlled by salt- or temperature-induced cooperative, swelling-shrinking properties from both layers. Based on their fast, reversible, bidirectional bending behavior, we further design two conceptual hybrid hydrogel actuators, serving as a six-arm gripper to capture, transport, and release an object and an electrical circuit switch to turn on-and-off a lamp. Different from the conventional two or multi-step methods for preparation of bilayer hydrogels, our simple, one-pot, one-step method and a new bilayer hydrogel system provide an innovative concept to explore new hydrogel-based actuators through combining different responsive materials that allow to program different stimulus for soft and intelligent materials applications.

Elastin Based Cell-laden Injectable Hydrogels with Tunable Gelation, Mechanical and Biodegradation Properties

Science.gov (United States)

Fathi, Ali; Mithieux, Suzanne M.; Wei, Hua; Chrzanowski, Wojciech; Valtchev, Peter; Weiss, Anthony S.; Dehghani, Fariba

2015-01-01

Injectable hydrogels made from extracellular matrix proteins such as elastin show great promise for various biomedical applications. Use of cytotoxic reagents, fixed gelling behavior, and lack of mechanical strength in these hydrogels are the main associated drawbacks. The aim of this study was to develop highly cytocompatible and injectable elastin-based hydrogels with alterable gelation characteristics, favorable mechanical properties and structural stability for load bearing applications. A thermoresponsive copolymer, poly(N-isopropylacrylamide-co-polylactide-2-hydroxyethyl methacrylate-co-oligo(ethylene glycol)monomethyl ether methacrylate, was functionalized with succinimide ester groups by incorporating N-acryloxysuccinimide monomer. These ester groups were exploited to covalently bond this polymer, denoted as PNPHO, to different proteins with primary amine groups such as α-elastin in aqueous media. The incorporation of elastin through covalent bond formation with PNPHO promotes the structural stability, mechanical properties and live cell proliferation within the structure of hydrogels. Our results demonstrated that elastin-co-PNPHO solutions were injectable through fine gauge needles and converted to hydrogels in situ at 37 °C in the absence of any crosslinking reagent. By altering PNPHO content, the gelling time of these hydrogels can be finely tuned within the range of 2 to 15 min to ensure compatibility with surgical requirements. In addition, these hydrogels exhibited compression moduli in the range of 40 to 145 kPa, which are substantially higher than those of previously developed elastin-based hydrogels. These hydrogels were highly stable in the physiological environment with the evidence of 10 wt% mass loss in 30 days of incubation in a simulated environment. This class of hydrogels is in vivo bioabsorbable due to the gradual increase of the lower critical solution temperature of the copolymer to above 37 °C due to the cleavage of polylactide from

Mussel-inspired tough hydrogels with self-repairing and tissue adhesion

Science.gov (United States)

Gao, Zijian; Duan, Lijie; Yang, Yongqi; Hu, Wei; Gao, Guanghui

2018-01-01

The mussel-inspired polymeric hydrogels have been attractively explored owing to their self-repairing or adhesive property when the catechol groups of dopamine could chelate metal ions. However, it was a challenge for self-repairing hydrogels owning high mechanical properties. Herein, a synergistic strategy was proposed by combining catechol-Fe3+ complexes and hydrophobic association. The resulting hydrogels exhibited seamless self-repairing behavior, tissue adhesion and high mechanical property. Moreover, the pH-dependent stoichiometry of catechol-Fe3+ and temperature-sensitive hydrophobic association endue hydrogels with pH/thermo responsive characteristics. Subsequently, the self-repairing rate and mechanical property of hydrogels were investigated at different pH and temperature. This bio-inspired strategy would build an avenue for designing and constructing a new generation of self-repairing, tissue-adhesive and tough hydrogel.

A Thixotropic Polyglycerol Sebacate-Based Supramolecular Hydrogel as an Injectable Drug Delivery Matrix

Directory of Open Access Journals (Sweden)

Hongye Ye

2016-04-01

Full Text Available We have developed a “self-healing” polyglycerol sebacate—polyethylene glycol methyl ether methacrylate (PGS-PEGMEMA/α-Cyclodextrin (αCD hydrogel which could be sheared into a liquid during injection and has the potential to quickly “heal” itself back into gel post-injection. This hydrogel was shown to be biocompatible and biodegradable and therefore appropriate for use in vivo. Furthermore, the storage and loss moduli of the hydrogels could be tuned (by varying the concentration of αCD between a fraction of a kPa to a few 100 kPa, a range that coincides with the moduli of cells and human soft tissues. This property would allow for this hydrogel to be used in vivo with maximal mechanical compatibility with human soft tissues. In vitro experiments showed that the hydrogel demonstrated a linear mass erosion profile and a biphasic drug (doxorubicin release profile: Phase I was primarily driven by diffusion and Phase II was driven by hydrogel erosion. The diffusion mechanism was modeled with the First Order equation and the erosion mechanism with the Hopfenberg equation. This established fitting model could be used to predict releases with other drugs and estimate the composition of the hydrogel required to achieve a desired release rate.

An injectable and biodegradable hydrogel based on poly(α,β-aspartic acid) derivatives for localized drug delivery.

Science.gov (United States)

Lu, Caicai; Wang, Xiaojuan; Wu, Guolin; Wang, Jingjing; Wang, Yinong; Gao, Hui; Ma, Jianbiao

2014-03-01

An injectable hydrogel via hydrazone cross-linking was prepared under mild conditions without addition of cross-linker or catalyst. Hydrazine and aldehyde modified poly(aspartic acid)s were used as two gel precursors. Both of them are water-soluble and biodegradable polymers with a protein-like structure, and obtained by aminolysis reaction of polysuccinimide. The latter can be prepared by thermal polycondensation of aspartic acid. Hydrogels were prepared in PBS solution and characterized by different methods including gel content and swelling, Fourier transformed-infrared spectroscopy, and in vitro degradation experiment. A scanning electron microscope viewed the interior morphology of the obtained hydrogels, which showed porous three-dimensional structures. Different porous sizes were present, which could be well controlled by the degree of aldehyde substitution in precursor poly(aspartic acid) derivatives. The doxorubicin-loaded hydrogels were prepared and showed a pH-sensitive release profile. The release rate can be accelerated by decreasing the environmental pH from a physiological to a weak acidic condition. Moreover, the cell adhesion and growth behaviors on the hydrogel were studied and the polymeric hydrogel showed good biocompatibility. Copyright © 2013 Wiley Periodicals, Inc.

Structure and Properties of Hydrophobic Aggregation Hydrogel with Chemical Sensitive Switch

Directory of Open Access Journals (Sweden)

Jiufang Duan

2017-01-01

Full Text Available Hydrogels with chemical sensitive switch have control release properties in special environments. A series of polyacrylamide-octadecyl methacrylate hydrogels crosslinked by N,N′-bis (acryloyl cystamine were synthesized as potential chemical sensitive system. When this hydrogel encounters dithiothreitol it can change its quality. The properties of the hydrogels were characterized by infrared spectroscopy, contact angle, and scanning electron microscopy. The water absorption of the hydrogel has the maximum value of 475%, when the content of octadecyl methacrylate is 5 wt%. The amount of weight loss was changed from 34.6% to 17.2%, as the content of octadecyl methacrylate increased from 3 wt% to 9.4 wt%. At the same time, the stress of the hydrogel decreased from 67.01% to 47.61%; the strength of the hydrogel reaches to the maximum 0.367 Mpa at 7 wt% octadecyl methacrylate. The increasing content of octadecyl methacrylate from 3 wt% to 9.4 wt% can enhance the hydrophobicity of the hydrogel; the contact angle of water to hydrogel changed from 14.10° to 19.62°. This hydrogel has the porous structure which permits loading of oils into the gel matrix. The functionalities of the hydrogel make it have more widely potential applications in chemical sensitive response materials.

Injectable TEMPO-oxidized nanofibrillated cellulose/biphasic calcium phosphate hydrogel for bone regeneration.

Science.gov (United States)

Safwat, Engie; Hassan, Mohammad L; Saniour, Sayed; Zaki, Dalia Yehia; Eldeftar, Mervat; Saba, Dalia; Zazou, Mohamed

2018-05-01

Nanofibrillated cellulose, obtained from rice straw agricultural wastes was used as a substrate for the preparation of a new injectable and mineralized hydrogel for bone regeneration. Tetramethyl pyridine oxyl (TEMPO) oxidized nanofibrillated cellulose, was mineralized through the incorporation of a prepared and characterized biphasic calcium phosphate at a fixed ratio of 50 wt%. The TEMPO-oxidized rice straw nanofibrillated cellulose was characterized using transmission electron microscopy, Fourier transform infrared, and carboxylic content determination. The injectability and viscosity of the prepared hydrogel were evaluated using universal testing machine and rheometer testing, respectively. Cytotoxicity and alkaline phosphatase level tests on osteoblast like-cells for in vitro assessment of the biocompatibility were investigated. Results revealed that the isolated rice straw nanofibrillated cellulose is a nanocomposite of the cellulose nanofibers and silica nanoparticles. Rheological properties of the tested materials are suitable for use as injectable material and of nontoxic effect on osteoblast-like cells, as revealed by the positive alkaline phosphate assay. However, nanofibrillated cellulose/ biphasic calcium phosphate hydrogel showed higher cytotoxicity and lower bioactivity test results when compared to that of nanofibrillated cellulose.

Nanodiamond-based injectable hydrogel for sustained growth factor release: Preparation, characterization and in vitro analysis.

Science.gov (United States)

Pacelli, Settimio; Acosta, Francisca; Chakravarti, Aparna R; Samanta, Saheli G; Whitlow, Jonathan; Modaresi, Saman; Ahmed, Rafeeq P H; Rajasingh, Johnson; Paul, Arghya

2017-08-01

Nanodiamonds (NDs) represent an emerging class of carbon nanomaterials that possess favorable physical and chemical properties to be used as multifunctional carriers for a variety of bioactive molecules. Here we report the synthesis and characterization of a new injectable ND-based nanocomposite hydrogel which facilitates a controlled release of therapeutic molecules for regenerative applications. In particular, we have formulated a thermosensitive hydrogel using gelatin, chitosan and NDs that provides a sustained release of exogenous human vascular endothelial growth factor (VEGF) for wound healing applications. Addition of NDs improved the mechanical properties of the injectable hydrogels without affecting its thermosensitive gelation properties. Biocompatibility of the generated hydrogel was verified by in vitro assessment of apoptotic gene expressions and anti-inflammatory interleukin productions. NDs were complexed with VEGF and the inclusion of this complex in the hydrogel network enabled the sustained release of the angiogenic growth factor. These results suggest for the first time that NDs can be used to formulate a biocompatible, thermosensitive and multifunctional hydrogel platform that can function both as a filling agent to modulate hydrogel properties, as well as a delivery platform for the controlled release of bioactive molecules and growth factors. One of the major drawbacks associated with the use of conventional hydrogels as carriers of growth factors is their inability to control the release kinetics of the loaded molecules. In fact, in most cases, a burst release is inevitable leading to diminished therapeutic effects and unsuccessful therapies. As a potential solution to this issue, we hereby propose a strategy of incorporating ND complexes within an injectable hydrogel matrix. The functional groups on the surface of the NDs can establish interactions with the model growth factor VEGF and promote a prolonged release from the polymer network

Long-term follow-up after urethral injection with polyacrylamide hydrogel for female stress incontinence

DEFF Research Database (Denmark)

Mouritsen, Lone; Lose, Gunnar; Møller-Bek, Karl

2014-01-01

Urethral injection therapy for treatment of stress urinary incontinence has been in use for years, but only a few long-term follow-up studies have been published. Twenty-five women, injected with polyacrylamide hydrogel 8 years earlier, were invited for follow-up. Twenty-four could be contacted; 15...... had had no further treatment, seven had been re-operated with placement of mid-urethral slings, and two had been re-injected with polyacrylamide hydrogel. Eleven women attended for objective examination; all non-attenders were interviewed by telephone. Subjectively, in 44% the stress incontinence...... was cured or much improved, with a positive outcome according to the King's Health Questionnaire. Objectively, all patients had visible polyacrylamide hydrogel deposits on vaginal ultrasonography. No local adverse reactions were seen in the vaginal mucosa. The results of a later mid-urethral sling were...

Injectable, degradable, electroactive nanocomposite hydrogels containing conductive polymer nanoparticles for biomedical applications

Directory of Open Access Journals (Sweden)

Wang QM

2016-01-01

Full Text Available Qinmei Wang,1 Qiong Wang,2 Wei Teng2 1Laboratory of Biomaterials, Key Laboratory on Assisted Circulation, Ministry of Health, Cardiovascular Division, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, People’s Republic of China; 2Department of Prosthodontics, Hospital of Stomatology, Institute of Stomatological Research, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, People’s Republic of China Abstract: Injectable electroactive hydrogels (eGels are promising in regenerative medicine and drug delivery, however, it is still a challenge to obtain such hydrogels simultaneously possessing other properties including uniform structure, degradability, robustness, and biocompatibility. An emerging strategy to endow hydrogels with desirable properties is to incorporate functional nanoparticles in their network. Herein, we report the synthesis and characterization of an injectable hydrogel based on oxidized alginate (OA crosslinking gelatin reinforced by electroactive tetraaniline-graft-OA nanoparticles (nEOAs, where nEOAs are expected to impart electroactivity besides reinforcement without significantly degrading the other properties of hydrogels. Assays of transmission electron microscopy, 1H nuclear magnetic resonance, and dynamic light scattering reveal that EOA can spontaneously and quickly self-assemble into robust nanoparticles in water, and this nanoparticle structure can be kept at pH 3~9. Measurement of the gel time by rheometer and the stir bar method confirms the formation of the eGels, and their gel time is dependent on the weight content of nEOAs. As expected, adding nEOAs to hydrogels does not cause the phase separation (scanning electron microscopy observation, but it improves mechanical strength up to ~8 kPa and conductivity up to ~10-6 S/cm in our studied range. Incubating eGels in phosphate-buffered saline leads to their further swelling with an increase of water content <6% and gradual degradation

An injectable calcium phosphate-alginate hydrogel-umbilical cord mesenchymal stem cell paste for bone tissue engineering

Science.gov (United States)

Zhao, Liang; Weir, Michael D.; Xu, Hockin H. K.

2010-01-01

The need for bone repair has increased as the population ages. Stem cell-scaffold approaches hold immense promise for bone tissue engineering. However, currently, preformed scaffolds for cell delivery have drawbacks including the difficulty to seed cells deep into the scaffold, and inability for injection in minimally invasive surgeries. Current injectable polymeric carriers and hydrogels are too weak for load-bearing orthopedic application. The objective of this study was to develop an injectable and mechanically-strong stem cell construct for bone tissue engineering. Calcium phosphate cement (CPC) paste was combined with hydrogel microbeads encapsulating human umbilical cord mesenchymal stem cells (hUCMSCs). The hUCMSC-encapsulating composite paste was fully injectable under small injection forces. Cell viability after injection matched that in hydrogel without CPC and without injection. Mechanical properties of the construct matched the reported values of cancellous bone, and were much higher than previous injectable polymeric and hydrogel carriers. hUCMSCs in the injectable constructs osteodifferentiated, yielding high alkaline phosphatase, osteocalcin, collagen type I, and osterix gene expressions at 7 d, which were 50–70 fold higher than those at 1 d. Mineralization by the hUCMSCs at 14 d was 100-fold that at 1 d. In conclusion, a fully-injectable, mechanically-strong, stem cell-CPC scaffold construct was developed. The encapsulated hUCMSCs remained viable, osteodifferentiated, and synthesized bone minerals. The new injectable stem cell construct with load-bearing capability may enhance bone regeneration in minimally-invasive and other orthopedic surgeries. PMID:20570346

Locally Targeted Delivery of a Micron-Size Radiation Therapy Source Using Temperature-Sensitive Hydrogel

Energy Technology Data Exchange (ETDEWEB)

Kim, Yusung, E-mail: yusung-kim@uiowa.edu [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Seol, Dong Rim [Department of Orthopaedic Surgery, The University of Iowa, Iowa City, Iowa (United States); Mohapatra, Sucheta [Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa (United States); Sunderland, John J. [Department of Radiology, The University of Iowa, Iowa City, Iowa (United States); Schultz, Michael K. [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Department of Radiology, The University of Iowa, Iowa City, Iowa (United States); Domann, Frederick E. [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Department of Surgery, The University of Iowa, Iowa City, Iowa (United States); Lim, Tae-Hong [Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa (United States)

2014-04-01

Purpose: To propose a novel radiation therapy (RT) delivery modality: locally targeted delivery of micron-size RT sources by using temperature-sensitive hydrogel (RT-GEL) as an injectable vehicle. Methods and Materials: Hydrogel is a water-like liquid at room temperature but gels at body temperature. Two US Food and Drug Administration-approved polymers were synthesized. Indium-111 (In-111) was used as the radioactive RT-GEL source. The release characteristics of In-111 from polymerized RT-GEL were evaluated. The injectability and efficacy of RT-GEL delivery to human breast tumor were tested using animal models with control datasets of RT-saline injection. As proof-of-concept studies, a total of 6 nude mice were tested by injecting 4 million tumor cells into their upper backs after a week of acclimatization. Three mice were injected with RT-GEL and 3 with RT-saline. Single-photon emission computed tomography (SPECT) and CT scans were performed on each mouse at 0, 24, and 48 h after injection. The efficacy of RT-GEL was determined by comparison with that of the control datasets by measuring kidney In-111 accumulation (mean nCi/cc), representing the distant diffusion of In-111. Results: RT-GEL was successfully injected into the tumor by using a 30-gauge needle. No difficulties due to polymerization of hydrogel during injection and intratumoral pressure were observed during RT-GEL injection. No back flow occurred for either RT-GEL or RT-saline. The residual tumor activities of In-111 were 49% at 24 h (44% at 48 h, respectively) for RT-GEL and 29% (22%, respectively) for RT-saline. Fused SPECT-CT images of RT-saline showed considerable kidney accumulation of In-111 (2886%, 261%, and 262% of RT-GEL at 0, 24, and 48 h, respectively). Conclusions: RT-GEL was successfully injected and showed much higher residual tumor activity: 170% (200%, respectively), than that of RT-saline at 24 h (48 h, respectively) after injection with a minimal accumulation of In-111 to the

Synthesis and characterization of a thermo-sensitive poly( N-methyl acryloylglycine methyl ester) used as a drug release carrier

Science.gov (United States)

Deng, Kui-Lin; Zhong, Hai-Bin; Jiao, Yi-Suo; Fan, Ting; Qiao, Xiao; Zhang, Peng-Fei; Ren, Xiao-Bo

2010-06-01

In this article, poly( N-methyl acryloylglycine methyl ester) (PNMAME) was prepared as a novel thermosensitive material with a lower critical solution temperature (LCST) at around 49.5°C. The chemical structures of the monomer NMAME and PNMAME were characterized by 1H NMR and IR measurements. The LCST was investigated systematically as a function of PNMAME concentration, inorganic salt solution and pH value. The results indicated that LCST of PNMAME was obviously dependent on PNMAME concentration and pH. The LCST was increased with a decrease in pH value and PNMAME concentration. To obtain a thermo-sensitive hydrogel with the phase transition temperature close to human body temperature, the copolymerization was conducted between NMAME and N-acryloylglycine ethyl ester (NAGEE). The release behavior of caffeine was evaluated at different temperatures and contents of cross-linkers ( N, N-methylenebis(acrylamide) (NMBA)). The increase of cross-linker content led to a decrease in the release rate of caffeine due to higher crossing density in the hydrogel network. In addition, a faster release of caffeine from the hydrogel with 3% NMBA at 37°C was found in contrast to that at 18°C.

Intra-Articular Polyacrylamide Hydrogel Injections Are Not Innocent

Directory of Open Access Journals (Sweden)

Murat Tonbul

2014-01-01

Full Text Available Osteoarthritis is a chronic disorder characterized by joint cartilage degeneration with concomitant changes in the synovium and subchondral bone metabolism. Many conservative treatment modalities, one of which is intra-articular injections, have been described for the treatment of this disorder. Traditionally, hyaluranic acid and corticosteroids are the agents that have been used for this purpose. Recently, polyacrylamide hydrogels are being used widely. Biocompatibility, nonbioabsorbability, and anti-infectious effect obtained by silver addition made polyacrylamide hydrogels more popular. In this paper, we present a case and the method of our management, in whom host tissue reaction (foreign body granuloma, edema, inflammation, and redness induration has been observed, as the first and unique adverse effect reported in the literature.

In Vivo Imaging of the Stability and Sustained Cargo Release of an Injectable Amphipathic Peptide-Based Hydrogel.

Science.gov (United States)

Oyen, Edith; Martin, Charlotte; Caveliers, Vicky; Madder, Annemieke; Van Mele, Bruno; Hoogenboom, Richard; Hernot, Sophie; Ballet, Steven

2017-03-13

Hydrogels are promising materials for biomedical applications such as tissue engineering and controlled drug release. In the past two decades, the peptide hydrogel subclass has attracted an increasing level of interest from the scientific community because of its numerous advantages, such as biocompatibility, biodegradability, and, most importantly, injectability. Here, we report on a hydrogel consisting of the amphipathic hexapeptide H-FEFQFK-NH 2 , which has previously shown promising in vivo properties in terms of releasing morphine. In this study, the release of a small molecule, a peptide, and a protein cargo as representatives of the three major drug classes is directly visualized by in vivo fluorescence and nuclear imaging. In addition, the in vivo stability of the peptide hydrogel system is investigated through the use of a radiolabeled hydrogelator sequence. Although it is shown that the hydrogel remains present for several days, the largest decrease in volume takes place within the first 12 h of subcutaneous injection, which is also the time frame wherein the cargos are released. Compared to the situation in which the cargos are injected in solution, a prolonged release profile is observed up to 12 h, showing the potential of our hydrogel system as a scaffold for controlled drug delivery. Importantly, this study elucidates the release mechanism of the peptide hydrogel system that seems to be based on erosion of the hydrogel providing a generally applicable controlled release platform for small molecule, peptide, and protein drugs.

Injectable, degradable, electroactive nanocomposite hydrogels containing conductive polymer nanoparticles for biomedical applications.

Science.gov (United States)

Wang, Qinmei; Wang, Qiong; Teng, Wei

2016-01-01

Injectable electroactive hydrogels (eGels) are promising in regenerative medicine and drug delivery, however, it is still a challenge to obtain such hydrogels simultaneously possessing other properties including uniform structure, degradability, robustness, and biocompatibility. An emerging strategy to endow hydrogels with desirable properties is to incorporate functional nanoparticles in their network. Herein, we report the synthesis and characterization of an injectable hydrogel based on oxidized alginate (OA) crosslinking gelatin reinforced by electroactive tetraaniline-graft-OA nanoparticles (nEOAs), where nEOAs are expected to impart electroactivity besides reinforcement without significantly degrading the other properties of hydrogels. Assays of transmission electron microscopy, (1)H nuclear magnetic resonance, and dynamic light scattering reveal that EOA can spontaneously and quickly self-assemble into robust nanoparticles in water, and this nanoparticle structure can be kept at pH 3~9. Measurement of the gel time by rheometer and the stir bar method confirms the formation of the eGels, and their gel time is dependent on the weight content of nEOAs. As expected, adding nEOAs to hydrogels does not cause the phase separation (scanning electron microscopy observation), but it improves mechanical strength up to ~8 kPa and conductivity up to ~10(-6) S/cm in our studied range. Incubating eGels in phosphate-buffered saline leads to their further swelling with an increase of water content <6% and gradual degradation. When growing mesenchymal stem cells on eGels with nEOA content ≤14%, the growth curves and morphology of cells were found to be similar to that on tissue culture plastic; when implanting these eGels on a chick chorioallantoic membrane for 1 week, mild inflammation response appeared without any other structural changes, indicating their good in vitro and in vivo biocompatibility. With injectability, uniformity, degradability, electroactivity, relative

Local application of a gentamicin-loaded thermo-responsive hydrogel allows for fracture healing upon clearance of a high Staphylococcus aureus load in a rabbit model

OpenAIRE

G-JA ter Boo; T Schmid; I Zderic; D Nehrbass; K Camenisch; RG Richards; DW Grijpma; TF Moriarty; D Eglin

2018-01-01

ntibiotic-loaded biomaterials (ALBs) have emerged as a potential useful adjunctive antimicrobial measure for the prevention of infection in open fracture care. A biodegradable thermo-responsive poly(N-isopropylacrylamide) grafted hyaluronic acid (HApN) hydrogel loaded with gentamicin has recently been shown to prevent implant-related infection in a rabbit osteosynthesis model. The primary aim of this study was to determine the influence of this HApN hydrogel on bone healing at an early stage ...

Radiation-induced synthesis and swelling properties of p(2-hydroxyethyl methacrylate/itaconic acid/oligo (ethylene glycol) acrylate) terpolymeric hydrogels

International Nuclear Information System (INIS)

Micic, M.; Stamenic, D.; Suljovrujic, E.

2012-01-01

Since it is presumed that by incorporation of pH-responsive (IA) and temperature-responsive (OEGA) co-monomers, it is possible to prepare P(HEMA/IA/OEGA) hydrogels with dual (pH and thermo) responsiveness, the main purpose of our study is to investigate the influence of different mole fractions of IA and especially OEGA on the diversity of the swelling properties of the obtained hydrogels. For that reason, a series of terpolymeric hydrogels with different mole ratios of 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA) and oligo(ethylene glycol) acrylates (OEGA) was synthesised by gamma radiation. The obtained hydrogels were characterised by swelling studies in the wide pH (2.2–9.0) and temperature range (20–70 °C), confirming dual (pH and thermo) responsiveness and a large variation in the swelling capability. It was observed that the equilibrium swelling of P(HEMA/IA/OEGA) hydrogels, for a constant amount of IA, increased progressively with an increase in OEGA share. On the other hand, the dissociation of carboxyl groups from IA occurs at pH>4; therefore, small mole fractions of IA render good pH sensitivity and a large increase in the swelling capacity of these hydrogels at higher pH values. Additional characterisation of structure and properties was conducted by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and mechanical measurements, confirming that the inherent properties of P(HEMA/IA/OEGA) hydrogels can be significantly tuned by variation in their composition. According to all presented, it seems that the obtained hydrogels can be a beneficial synergetic combination for controlled delivery of bioactive molecules such as drugs, peptides, proteins, etc. - Highlights: ► pH- and thermo-sensitive P(HEMA/IA/OEGA) hydrogels were synthesised by γ radiation. ► OEGA units have a large hydrophilic potential. ► Swelling capacity increases with the OEGA content. ► Variation in composition of hydrogels can give

ph Sensitive hydrogel as colon specific drug delivery

International Nuclear Information System (INIS)

Alarifi, A.S.

2011-01-01

γ-radiation induced graft copolymerization and crosslinking was for the synthesis of ph-sensitive hydrogels composed of poly (vinyl pyrrolidone) acrylic acid. The prepared hydrogels were subjected to swelling test to evaluate the effects of ph and ionic strength of the surrounding solution. Drastic changes in the swelling parameters where observed by changing the surrounding solution ph values. The release of ibuprofen from hydrogels was monitored as a function of time at ph 1 and ph 7 in order to evaluate the prepared copolymer ability for colon- specific drug carrier uses.

Synthesis of a novel thermo/pH sensitive nanogel based on salep modified graphene oxide for drug release

Energy Technology Data Exchange (ETDEWEB)

Bardajee, Ghasem Rezanejade, E-mail: rezanejad@pnu.ac.ir; Hooshyar, Zari; Farsi, Maryam; Mobini, Akram; Sang, Golnaz

2017-03-01

Nanogels (NGs) are three-dimensional water soluble cross-linked hydrogel materials in the nanoscale size range with a high loading capacity for guest molecules and act as drug carrier systems. In the present work, a new type of thermo/pH sensitive NG comprising salep modified graphene oxide (SMGO) with branched N-isopropylacrylamide (NIPAM) and acrylic acid (AA) was prepared. The SMGO/P(NIPAM-co-AA) NGs exhibited nanoporous structure and spherical particles with diameters about 82 nm as characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The samples were also characterized by Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA) to further confirm about the formation of NGs. Doxorubicin (DOX) loaded SMGO/P(NIPAM-co-AA) NGs showed thermo/pH dependent releasing behavior: slow drug release at neutral pH and lower temperature but increased significantly in acidic pH and higher temperature, without any burst release. In addition, the NGs exhibited no effect on the cell viability in the tested concentration range up to 410 μg/mL and drug release systems enhanced toxicity to HeLa cells when compared to the equivalent dose of the free drug. Overall, our results put forth NGs as potential candidates in the development of a new nanocarrier for anti-cancer drug delivery. - Highlights: • A novel thermo/pH sensitive nanogels (NGs) was successfully synthesized. • NGs showed high loading capacity for DOX drug and slow drug release at neutral pH. • NGs exhibited no effect on the cell viability in the tested concentration range.

Synthesis of a novel thermo/pH sensitive nanogel based on salep modified graphene oxide for drug release

International Nuclear Information System (INIS)

Bardajee, Ghasem Rezanejade; Hooshyar, Zari; Farsi, Maryam; Mobini, Akram; Sang, Golnaz

2017-01-01

Nanogels (NGs) are three-dimensional water soluble cross-linked hydrogel materials in the nanoscale size range with a high loading capacity for guest molecules and act as drug carrier systems. In the present work, a new type of thermo/pH sensitive NG comprising salep modified graphene oxide (SMGO) with branched N-isopropylacrylamide (NIPAM) and acrylic acid (AA) was prepared. The SMGO/P(NIPAM-co-AA) NGs exhibited nanoporous structure and spherical particles with diameters about 82 nm as characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The samples were also characterized by Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA) to further confirm about the formation of NGs. Doxorubicin (DOX) loaded SMGO/P(NIPAM-co-AA) NGs showed thermo/pH dependent releasing behavior: slow drug release at neutral pH and lower temperature but increased significantly in acidic pH and higher temperature, without any burst release. In addition, the NGs exhibited no effect on the cell viability in the tested concentration range up to 410 μg/mL and drug release systems enhanced toxicity to HeLa cells when compared to the equivalent dose of the free drug. Overall, our results put forth NGs as potential candidates in the development of a new nanocarrier for anti-cancer drug delivery. - Highlights: • A novel thermo/pH sensitive nanogels (NGs) was successfully synthesized. • NGs showed high loading capacity for DOX drug and slow drug release at neutral pH. • NGs exhibited no effect on the cell viability in the tested concentration range.

Injectable polypeptide hydrogels via methionine modification for neural stem cell delivery.

Science.gov (United States)

Wollenberg, A L; O'Shea, T M; Kim, J H; Czechanski, A; Reinholdt, L G; Sofroniew, M V; Deming, T J

2018-04-05

Injectable hydrogels with tunable physiochemical and biological properties are potential tools for improving neural stem/progenitor cell (NSPC) transplantation to treat central nervous system (CNS) injury and disease. Here, we developed injectable diblock copolypeptide hydrogels (DCH) for NSPC transplantation that contain hydrophilic segments of modified l-methionine (Met). Multiple Met-based DCH were fabricated by post-polymerization modification of Met to various functional derivatives, and incorporation of different amino acid comonomers into hydrophilic segments. Met-based DCH assembled into self-healing hydrogels with concentration and composition dependent mechanical properties. Mechanical properties of non-ionic Met-sulfoxide formulations (DCH MO ) were stable across diverse aqueous media while cationic formulations showed salt ion dependent stiffness reduction. Murine NSPC survival in DCH MO was equivalent to that of standard culture conditions, and sulfoxide functionality imparted cell non-fouling character. Within serum rich environments in vitro, DCH MO was superior at preserving NSPC stemness and multipotency compared to cell adhesive materials. NSPC in DCH MO injected into uninjured forebrain remained local and, after 4 weeks, exhibited an immature astroglial phenotype that integrated with host neural tissue and acted as cellular substrates that supported growth of host-derived axons. These findings demonstrate that Met-based DCH are suitable vehicles for further study of NSPC transplantation in CNS injury and disease models. Copyright © 2018 Elsevier Ltd. All rights reserved.

Novel Injectable Pentablock Copolymer Based Thermoresponsive Hydrogels for Sustained Release Vaccines.

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Bobbala, Sharan; Tamboli, Viral; McDowell, Arlene; Mitra, Ashim K; Hook, Sarah

2016-01-01

The need for multiple vaccinations to enhance the immunogenicity of subunit vaccines may be reduced by delivering the vaccine over an extended period of time. Here, we report two novel injectable pentablock copolymer based thermoresponsive hydrogels made of polyethyleneglycol-polycaprolactone-polylactide-polycaprolactone-polyethyleneglycol (PEG-PCL-PLA-PCL-PEG) with varying ratios of polycaprolactone (PCL) and polylactide (PLA), as single shot sustained release vaccines. Pentablock copolymer hydrogels were loaded with vaccine-encapsulated poly lactic-co-glycolic acid nanoparticles (PLGA-NP) or with the soluble vaccine components. Incorporation of PLGA-NP into the thermoresponsive hydrogels increased the complex viscosity of the gels, lowered the gelation temperature, and minimized the burst release of antigen and adjuvants. The two pentablock hydrogels stimulated both cellular and humoral responses. The addition of PLGA-NP to the hydrogels sustained immune responses for up to 49 days. The polymer with a higher ratio of PCL to PLA formed a more rigid gel, induced stronger immune responses, and stimulated effective anti-tumor responses in a prophylactic melanoma tumor model.

An Optimized Injectable Hydrogel Scaffold Supports Human Dental Pulp Stem Cell Viability and Spreading

Directory of Open Access Journals (Sweden)

T. D. Jones

2016-01-01

Full Text Available Introduction. HyStem-C™ is a commercially available injectable hydrogel composed of polyethylene glycol diacrylate (PEGDA, hyaluronan (HA, and gelatin (Gn. These components can be mechanically tuned to enhance cell viability and spreading. Methods. The concentration of PEGDA with an added disulfide bond (PEGSSDA was varied from 0.5 to 8.0% (w/v to determine the optimal concentration for injectable clinical application. We evaluated the cell viability of human dental pulp stem cells (hDPSCs embedded in 2% (w/v PEGSSDA-HA-Gn hydrogels. Volume ratios of HA : Gn from 100 : 0 to 25 : 75 were varied to encourage hDPSC spreading. Fibronectin (Fn was added to our model to determine the effect of extracellular matrix protein concentration on hDPSC behavior. Results. Our preliminary data suggests that the hydrogel gelation time decreased as the PEGSSDA cross-linker concentration increased. The PEGSSDA-HA-Gn was biocompatible with hDPSCs, and increased ratios of HA : Gn enhanced cell viability for 14 days. Additionally, cell proliferation with added fibronectin increased significantly over time at concentrations of 1.0 and 10.0 μg/mL in PEGDA-HA-Gn hydrogels, while cell spreading significantly increased at Fn concentrations of 0.1 μg/mL. Conclusions. This study demonstrates that PEG-based injectable hydrogels maintain hDPSC viability and facilitate cell spreading, mainly in the presence of extracellular matrix (ECM proteins.

Fabrication of stimuli-sensitive hydrogel for the removal of cesium

Energy Technology Data Exchange (ETDEWEB)

Yang, Hee-Man; Bong, Sang Bum; Park, Chan Woo; Lee, Kune Woo; Seo, Bum-Kyoung; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

The nuclear accident at the Fukushima Daiichi nuclear power station in 2011 released a huge quantity of radioactive contaminants into the environment.1 Among these, cesium Cs-137 is the most problematic contaminant due to its long half-life (30.2 years), and high-energy gamma ray (γ-ray) emissions. 2 Various surface including road, roof, house, building were contaminated with Cs-137. These coating materials have some problems and limitation such as toxic component, and lack of reusability of materials related to the cost. Thus, a more cost-effective and environmental friendly coating materials is still desired. 3 In the present study, the stimuli-sensitive hydrogel were fabricated for the removal of radioactive Cs from solid surface. We describe the morphology, structure, and physical property of these stimuli sensitive hydrogel. In addition, their ability to eliminate cesium was also evaluated. The smart hydrogel coating materials showed an excellent morphology change from the liquid to film by addition of Ca ion. Therefore, the stimuli-sensitive hydrogel demonstrated good potential for the treatment of contaminated surface for the removal of radioactive cesium.

Fabrication of stimuli-sensitive hydrogel for the removal of cesium

International Nuclear Information System (INIS)

Yang, Hee-Man; Bong, Sang Bum; Park, Chan Woo; Lee, Kune Woo; Seo, Bum-Kyoung; Moon, Jei Kwon

2015-01-01

The nuclear accident at the Fukushima Daiichi nuclear power station in 2011 released a huge quantity of radioactive contaminants into the environment.1 Among these, cesium Cs-137 is the most problematic contaminant due to its long half-life (30.2 years), and high-energy gamma ray (γ-ray) emissions. 2 Various surface including road, roof, house, building were contaminated with Cs-137. These coating materials have some problems and limitation such as toxic component, and lack of reusability of materials related to the cost. Thus, a more cost-effective and environmental friendly coating materials is still desired. 3 In the present study, the stimuli-sensitive hydrogel were fabricated for the removal of radioactive Cs from solid surface. We describe the morphology, structure, and physical property of these stimuli sensitive hydrogel. In addition, their ability to eliminate cesium was also evaluated. The smart hydrogel coating materials showed an excellent morphology change from the liquid to film by addition of Ca ion. Therefore, the stimuli-sensitive hydrogel demonstrated good potential for the treatment of contaminated surface for the removal of radioactive cesium

Sensitivity analyses of biodiesel thermo-physical properties under diesel engine conditions

DEFF Research Database (Denmark)

Cheng, Xinwei; Ng, Hoon Kiat; Gan, Suyin

2016-01-01

This reported work investigates the sensitivities of spray and soot developments to the change of thermo-physical properties for coconut and soybean methyl esters, using two-dimensional computational fluid dynamics fuel spray modelling. The choice of test fuels made was due to their contrasting...... saturation-unsaturation compositions. The sensitivity analyses for non-reacting and reacting sprays were carried out against a total of 12 thermo-physical properties, at an ambient temperature of 900 K and density of 22.8 kg/m3. For the sensitivity analyses, all the thermo-physical properties were set...... as the baseline case and each property was individually replaced by that of diesel. The significance of individual thermo-physical property was determined based on the deviations found in predictions such as liquid penetration, ignition delay period and peak soot concentration when compared to those of baseline...

The TRPM2 channel: A thermo-sensitive metabolic sensor.

Science.gov (United States)

Kashio, Makiko; Tominaga, Makoto

2017-09-03

Living organisms continually experience changes in ambient temperature. To detect such temperature changes for adaptive behavioral responses, we evolved the ability to sense temperature. Thermosensitive transient receptor potential (TRP) channels, so-called thermo-TRPs, are involved in many physiologic functions in diverse organisms and constitute important temperature sensors. One of the important roles of thermo-TRPs is detecting ambient temperature in sensory neurons. Importantly, the functional expression of thermo-TRPs is observed not only in sensory neurons but also in tissues and cells that are not exposed to drastic temperature changes, indicating that thermo-TRPs are involved in many physiologic functions within the body's normal temperature range. Among such thermo-TRPs, this review focuses on one thermo-sensitive metabolic sensor in particular, TRPM2, and summarizes recent progress to clarify the regulatory mechanisms and physiologic functions of TRPM2 at body temperature under various metabolic states.

Hyaluronic Acid (HA)-Polyethylene glycol (PEG) as injectable hydrogel for intervertebral disc degeneration patients therapy

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Putri Kwarta, Cityta; Widiyanti, Prihartini; Siswanto

2017-05-01

Chronic Low Back Pain (CLBP) is one health problem that is often encountered in a community. Inject-able hydrogels are the newest way to restore the disc thickness and hydration caused by disc degeneration by means of minimally invasive surgery. Thus, polymers can be combined to improve the characteristic properties of inject-able hydrogels, leading to use of Hyaluronic Acid (a natural polymer) and Polyethylene glycol (PEG) with Horse Radish Peroxide (HRP) cross linker enzymes. The swelling test results, which approaches were the ideal disc values, were sampled with variation of enzyme concentrations of 0.25 µmol/min/mL. The enzyme concentrations were 33.95%. The degradation test proved that the sample degradation increased along with the decrease of the HRP enzyme concentration. The results of the cytotoxicity assay with MTT assay method showed that all samples resulted in the 90% of living cells are not toxic. In vitro injection, models demonstrated that higher concentration of the enzymes was less state of gel which would rupture when released from the agarose gel. The functional group characterization shows the cross linking bonding in sample with enzyme adding. The conclusion of this study is PEG-HA-HRP enzyme are safe polymer composites which have a potential to be applied as an injectable hydrogel for intervertebral disc degeneration.

Data on the experiments of temperature-sensitive hydrogels for pH-sensitive drug release and the characterizations of materials

Directory of Open Access Journals (Sweden)

Wei Zhang

2018-04-01

Full Text Available This article contains experimental data on the strain sweep, the calibration curve of drug (doxorubicin, DOX and the characterizations of materials. Data included are related to the research article “Injectable and body temperature sensitive hydrogels based on chitosan and hyaluronic acid for pH sensitive drug release” (Zhang et al., 2017 [1]. The strain sweep experiments were performed on a rotational rheometer. The calibration curves were obtained by analyzing the absorbance of DOX solutions on a UV–vis-NIR spectrometer. Molecular weight (Mw of the hyaluronic acid (HA and chitosan (CS were determined by gel permeation chromatography (GPC. The deacetylation degree of CS was measured by acid base titration.

Peptide Drug Release Behavior from Biodegradable Temperature-Responsive Injectable Hydrogels Exhibiting Irreversible Gelation

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Kazuyuki Takata

2017-10-01

Full Text Available We investigated the release behavior of glucagon-like peptide-1 (GLP-1 from a biodegradable injectable polymer (IP hydrogel. This hydrogel shows temperature-responsive irreversible gelation due to the covalent bond formation through a thiol-ene reaction. In vitro sustained release of GLP-1 from an irreversible IP formulation (F(P1/D+PA40 was observed compared with a reversible (physical gelation IP formulation (F(P1. Moreover, pharmaceutically active levels of GLP-1 were maintained in blood after subcutaneous injection of the irreversible IP formulation into rats. This system should be useful for the minimally invasive sustained drug release of peptide drugs and other water-soluble bioactive reagents.

Injectable glycosaminoglycan-protein nano-complex in semi-interpenetrating networks: A biphasic hydrogel for hyaline cartilage regeneration.

Science.gov (United States)

Radhakrishnan, Janani; Subramanian, Anuradha; Sethuraman, Swaminathan

2017-11-01

Articular hyaline cartilage regeneration remains challenging due to its less intrinsic reparability. The study develops injectable biphasic semi-interpenetrating polymer networks (SIPN) hydrogel impregnated with chondroitin sulfate (ChS) nanoparticles for functional cartilage restoration. ChS loaded zein nanoparticles (∼150nm) prepared by polyelectrolyte-protein complexation were interspersed into injectable SIPNs developed by blending alginate with poly(vinyl alcohol) and calcium crosslinking. The hydrogel exhibited interconnected porous microstructure (39.9±5.8μm pore diameter, 57.7±5.9% porosity), 92% swellability and >350Pa elastic modulus. Primary chondrocytes compatibility, chondrocyte-matrix interaction with cell-cell clustering and spheroidal morphology was demonstrated in ChS loaded hydrogel and long-term (42days) proliferation was also determined. Higher fold expression of cartilage-specific genes sox9, aggrecan and collagen-II was observed in ChS loaded hydrogel while exhibiting poor expression of collagen-I. Immunoblotting of aggregan and collagen II demonstrate favorable positive influence of ChS on chondrocytes. Thus, the injectable biphasic SIPNs could be promising composition-mimetic substitute for cartilage restoration at irregular defects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Radiation induced variations in photoperiod-sensitivity, thermo-sensitivity and the number of days to heading in rice

International Nuclear Information System (INIS)

Hsieh, S.C.

1975-01-01

Radiation induced semi-dwarf mutants derived from five japonica type varieties of rice were studied with regard to their photoperiod-sensitivity, thermo-sensitivity and the number of days to heading. The experiment was carried out under the natural conditions at Taipei. The coefficient of photoperiod-sensitivity and thermo-sensitivity as developed by Oka (1954) were estimated for the mutants in comparison with their original varieties. It was observed that these various physiological characters could be altered easily by mutations. Mutants showed wider ranges in both positive and negative directions than their original varieties in all physiological characters studied. Even though heading date depends on both photoperiod-sensitivity and thermo-sensitivity, it was estimated which of the two contributed more to the induced earliness in each mutant. This offers a basis for selecting early maturing lines of rice

Stimuli-sensitive hydrogels: A novel ophthalmic drug delivery system

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Singh Vinod

2010-01-01

Full Text Available Background: Stimuli-sensitive hydrogels are three-dimensional, hydrophilic, polymeric networks capable of imbibing large amounts of water or biological fluids on stimulation, such as pH, temperature and ionic change. Aim: To develop hydrogels that are sensitive to stimuli, i.e. pH, in the cul-de-sac of the eye for providing a prolonged effect and increased bioavailability with reduction in frequency of administration. Materials and Methods: Hydrogels were formulated by using timolol maleate as the model drug, polyacrylic acid as the gelling agents, hydroxyl ethyl cellulose as the viscolizer and sodium chloride as the isotonic agent. Stirring of ingredients in pH 4 phosphate buffer at high speed was carried out. The dynamic dialysis technique was used for drug release studies. In vivo study for reduction in intraocular pressure was carried out by using albino rabbits. Statistical Analysis: Drug release studies data were used for statistical analysis in first-order plots, Higuchi plots and Peppas exponential plots. Student t-test was performed for in vivo study. Results: Viscosity of the hydrogel increases from 3.84 cps to 9.54 cps due to change in pH 4 to pH 7.4. The slope value of the Peppas equation was found to be 0.3081, 0.3743 and 0.2964. Up to 80% of drug was released in an 8 h drug release study. Sterile hydrogels with no ocular irritation were obtained. Conclusions: Hydrogels show increase in viscosity due to change in pH. Hydrogels were therapeutically effacious, stable, non-irritant and showed Fickian diffusion. In vivo results clearly show a prolonged reduction in intraocular pressure, which was helpful for reduction in the frequency of administration.

Reinforcement of thermoplastic chitosan hydrogel using chitin whiskers optimized with response surface methodology.

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Sun, Guohui; Zhang, Xin; Bao, Zixian; Lang, Xuqian; Zhou, Zhongzheng; Li, Yang; Feng, Chao; Chen, Xiguang

2018-06-01

To strengthen the mechanical strength of thermo-sensitive hydroxybutyl chitosan (HBC) hydrogel, chitin whiskers were used as sticker to fabricate reinforced HBC (HBCW) hydrogel by using response surface methodology. Unlike the intrinsic network of HBC hydrogel, HBCW hydrogel showed a laminar shape with firm structure. The preparation condition was optimized by three-factor-three-level Box-Behnken design. The maximum mechanical strength (1011.11 Pa) was achieved at 50 °C, when the concentrations of HBC and chitin whiskers were 5.1 wt% and 2.0 wt%, respectively. The effects of temperature, pH value and NaCl concentration on mechanical strength of HBCW hydrogels were investigated via the oscillatory stress sweeps. The results showed that HBCW hydrogel could reach the maximum stiffness (∼1126 Pa) at 37 °C pH 12.0. Low pH and high salty ions could decrease the stability of hydrogel, while chitin whiskers could increase the stress tolerance and related ruptured strain of HBCW hydrogels. Copyright © 2018. Published by Elsevier Ltd.

Encapsulation of Curcumin in Self-Assembling Peptide Hydrogels as Injectable Drug Delivery Vehicles

Science.gov (United States)

Altunbas, Aysegul; Lee, Seung Joon; Rajasekaran, Sigrid A.; Schneider, Joel P.; Pochan, Darrin J.

2011-01-01

Curcumin, a hydrophobic polyphenol, is an extract of turmeric root with antioxidant, anti-inflammatory and anti-tumorigenic properties. Its lack of water solubility and relatively low bioavailability set major limitations for its therapeutic use. In this study, a self-assembling peptide hydrogel is demonstrated to be an effective vehicle for the localized delivery of curcumin over sustained periods of time. The curcumin-hydrogel is prepared in-situ where curcumin encapsulation within the hydrogel network is accomplished concurrently with peptide self-assembly. Physical and in vitro biological studies were used to demonstrate the effectiveness of curcumin-loaded β-hairpin hydrogels as injectable agents for localized curcumin delivery. Notably, rheological characterization of the curcumin loaded hydrogel before and after shear flow have indicated solid-like properties even at high curcumin payloads. In vitro experiments with a medulloblastoma cell line confirm that the encapsulation of the curcumin within the hydrogel does not have an adverse effect on its bioactivity. Most importantly, the rate of curcumin release and its consequent therapeutic efficacy can be conveniently modulated as a function of the concentration of the MAX8 peptide. PMID:21601921

Device for simultaneous measurements of the optical and dielectric properties of hydrogels

International Nuclear Information System (INIS)

Gómez-Galván, F; Lara-Ceniceros, T; Mercado-Uribe, H

2012-01-01

We have designed an experimental device to simultaneously measure the light transmittance and dielectric properties of thermo-sensitive hydrogels. We have used this device to study poly(N-isopropylacrylamide) samples in order to understand the mechanism of water deliverance during the phase transition such hydrogels normally exhibit. We found that the phase transition can be observed dielectrically at low frequencies, when the isothermals obtained during the heating of the samples separate into two groups. The phenomenon occurs due to the increase of ions caused by the dissociation of water molecules released by the polymer, and corresponds to the drop of the optical transmittance

Modeling programmable deformation of self-folding all-polymer structures with temperature-sensitive hydrogels

International Nuclear Information System (INIS)

Guo, Wei; Zhou, Jinxiong; Li, Meie

2013-01-01

Combination of soft active hydrogels with hard passive polymers gives rise to all-polymer composites. The hydrogel is sensitive to external stimuli while the passive polymer is inert. Utilizing the different behaviors of two materials subject to environmental variation, for example temperature, results in self-folding soft machines. We report our efforts to model the programmable deformation of self-folding structures with temperature-sensitive hydrogels. The self-folding structures are realized either by constructing a bilayer structure or by incorporating hydrogels as hinges. The methodology and the results may aid the design, control and fabrication of 3D complex structures from 2D simple configurations through self-assembly. (paper)

Radiation processed hydrogels (wound dressings) for medical applications

International Nuclear Information System (INIS)

Varshney, Lalit

2004-01-01

Thermal analysis plays an important role in study and development of hydrogel materials for medical applications. Thermal stability of the ingredients which is important from the point of manufacturing, rate of evaporation for shelf life evaluation, determination of gelation and temperature responsive temperatures, cooling behaviour, gel elasticity, radiation effects etc. can be studied using thermal analysis equipment like Differential scanning calorimetry (DSC), Thermo-gravimetric analysis (TGA) and thermo-mechanical analysis (TMA). In this use of these techniques in development, evaluation and quality control of hydrogel wound dressing is discussed

Fast-responsive hydrogel as an injectable pump for rapid on-demand fluidic flow control.

Science.gov (United States)

Luo, Rongcong; Dinh, Ngoc-Duy; Chen, Chia-Hung

2017-05-01

Chemically synthesized functional hydrogels have been recognized as optimized soft pumps for on-demand fluidic regulation in micro-systems. However, the challenges regarding the slow responses of hydrogels have very much limited their application in effective fluidic flow control. In this study, a heterobifunctional crosslinker (4-hydroxybutyl acrylate)-enabled two-step hydrothermal phase separation process for preparing a highly porous hydrogel with fast response dynamics was investigated for the fabrication of novel microfluidic functional units, such as injectable valves and pumps. The cylinder-shaped hydrogel, with a diameter of 9 cm and a height of 2.5 cm at 25 °C, achieved a size reduction of approximately 70% in less than 30 s after the hydrogels were heated at 40 °C. By incorporating polypyrrole nanoparticles as photothermal transducers, a photo-responsive composite hydrogel was approached and exhibited a remotely triggerable fluidic regulation and pumping ability to generate significant flows, showing on-demand water-in-oil droplet generation by laser switching, whereby the droplet size could be tuned by adjusting the laser intensity and irradiation period with programmable manipulation.

Alginate hydrogel as a potential alternative to hyaluronic acid as submucosal injection material.

Science.gov (United States)

Kang, Ki Joo; Min, Byung-Hoon; Lee, Jun Haeng; Kim, Eun Ran; Sung, Chang Ohk; Cho, Joo Young; Seo, Soo Won; Kim, Jae J

2013-06-01

Sodium alginate is currently used in medical products, including drugs and cosmetic materials. It can also be used as a submucosal injection material due to its excellent water retention ability. Alginate with a high water retention ability is called alginate hydrogel (AH). The aim of this study was to investigate the usefulness of AH as a submucosal injection material. To investigate the optimal viscosity of AH as a submucosal injection material, we observed the changes in submucosal height from the initial submucosal height in the stomachs of six miniature pigs for each injection material tested (0.3 % AH, 0.5 % hyaluronic acid, glycerol). All submucosal heights were compared serially over time (3, 5, 10, 20, and 30 min). Both immediate and 1-week delayed tissue reactions were investigated endoscopically in the same living pigs. Histological analyses were performed after the animals had been sacrificed. In a preliminary study, we determined that 0.3 % sodium alginate mixed with BaCl2 (400 μl) was the optimal viscosity of AH as an injection material. Our comparison of submucosal height changes over time showed that there was a significant decrease in submucosal height just 3 min following the injection of hyaluronic acid and glycerol, but that following the injection of AH a significant decrease in submucosal height was observed only after 10 min (p injection site. Alginate hydrogel demonstrated long-lasting maintenance of submucosal elevation, safety, and cost-effectiveness in a pig model, which makes it a potential alternative to hyaluronic acid.

Studies on chemically crosslinkable carboxy terminated-poly(propylene fumarate-co-ethylene glycol)-acrylamide hydrogel as an injectable biomaterial

International Nuclear Information System (INIS)

Kallukalam, B C; Jayabalan, M; Sankar, V

2009-01-01

Carboxy terminated-poly(propylene fumarate)-co-ethylene glycol) (CT-PPF-co-PEG) was prepared and set into crosslinked hydrogel material with acrylamide. The setting studies reveal that this copolymer system can be used as an injectable material. The hydrogel material exhibits a higher degree of swelling, good mechanical strength and flexibility. The hydrogel favours adhesion of L929 fibroblast cells without proliferation on the surface. However, cardiac fibroblast cells (isolated from new born rat (Wistar) hearts) adhere and proliferate on the hydrogel due to the formation of synergistic hydrophilic-hydrophobic surface-by-surface reorganization.

Studies on chemically crosslinkable carboxy terminated-poly(propylene fumarate-co-ethylene glycol)-acrylamide hydrogel as an injectable biomaterial

Energy Technology Data Exchange (ETDEWEB)

Kallukalam, B C; Jayabalan, M [Polymer Division, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695 012 (India); Sankar, V, E-mail: muthujayabalan@rediffmail.co [Division of Cellular and Molecular Cardiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram 695 012 (India)

2009-02-15

Carboxy terminated-poly(propylene fumarate)-co-ethylene glycol) (CT-PPF-co-PEG) was prepared and set into crosslinked hydrogel material with acrylamide. The setting studies reveal that this copolymer system can be used as an injectable material. The hydrogel material exhibits a higher degree of swelling, good mechanical strength and flexibility. The hydrogel favours adhesion of L929 fibroblast cells without proliferation on the surface. However, cardiac fibroblast cells (isolated from new born rat (Wistar) hearts) adhere and proliferate on the hydrogel due to the formation of synergistic hydrophilic-hydrophobic surface-by-surface reorganization.

Biopolymer-based hydrogels as injectable materials for tissue repair scaffolds

International Nuclear Information System (INIS)

Fiejdasz, Sylwia; Szczubiałka, Krzysztof; Lewandowska-Łańcucka, Joanna; Nowakowska, Maria; Osyczka, Anna M

2013-01-01

The progress in tissue regeneration is strongly dependent on the development of biocompatible materials with properties resembling those of a native tissue. Also, the application of noninvasive methods of delivering the scaffold into the tissue defect is of great importance. In this study we present a group of biopolymer-based materials as potential injectable scaffolds. In contrast to other studies involving collagen neutralization or additional incubation of gel in genipin solution, we propose collagen and collagen–chitosan gels crosslinked in situ with genipin. Since some parameters of the cells should be considered in the microscale, the steady-state fluorescence anisotropy was applied to study the microenvironment of the gels. To our knowledge we are the first to report on microrheological properties, such as gel time and microviscosity, for this group of hydrogels. Rapid gelation at physiological temperatures found makes these materials of special interest in applications requiring gel injectability. Physico-chemical investigation showed the influence of the crosslinking agent concentration and chitosan addition on the crosslinking degree, swelling ratio, gel microviscosity, and the degradation rate. Strong correlation was revealed between the surface wettability and the viability of cultured mesenchymal stem cells. Cytotoxicity studies indicated that the collagen–chitosan hydrogels showed the best biocompatibility. (paper)

A novel vehicle for local protein delivery to the inner ear: injectable and biodegradable thermosensitive hydrogel loaded with PLGA nanoparticles.

Science.gov (United States)

Dai, Juan; Long, Wei; Liang, Zhongping; Wen, Lu; Yang, Fan; Chen, Gang

2018-01-01

Delivery of biomacromolecular drugs into the inner ear is challenging, mainly because of their inherent instability as well as physiological and anatomical barriers. Therefore, protein-friendly, hydrogel-based delivery systems following local administration are being developed for inner ear therapy. Herein, biodegradable poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) containing interferon α-2 b (IFN α-2 b) were loaded in chitosan/glycerophosphate (CS/GP)-based thermosensitive hydrogel for IFN delivery by intratympanic injection. The injectable hydrogel possessed a physiological pH and formed semi-solid gel at 37 °C, with good swelling and deswelling properties. The CS/GP hydrogel could slowly degrade as visualized by scanning electron microscopy (SEM). The presence of NPs in CS/GP gel largely influenced in vitro drug release. In the guinea pig cochlea, a 1.5- to 3-fold increase in the drug exposure time of NPs-CS/GP was found than those of the solution, NPs and IFN-loaded hydrogel. Most importantly, a prolonged residence time was attained without obvious histological changes in the inner ear. This biodegradable, injectable, and thermosensitive NPs-CS/GP system may allow longer delivery of protein drugs to the inner ear, thus may be a potential novel vehicle for inner ear therapy.

Radiation synthesis of stimuli-responsive membranes, hydrogels and adsorbents for separation purposes. Final report of a coordinated research project 2000-2004

International Nuclear Information System (INIS)

2005-08-01

This coordinated research project coordinated research work for the development of novel materials prepared by radiation processing techniques. Single and multi-pore polyamide membranes, fast thermo-responsive hydrogels, porous polymer monoliths, stimuli-responsive hydrogels based on natural and synthetic polymers, temperature responsive membranes, selective adsorbents, polymeric nanogels and novel non-ionic thermo-sensitive hydrogels were produced. The application areas explored for beneficially utilizing these novel materials included specialized drug delivery systems (DDS), selective adsorbents, nanopores for single molecule detection, membranes for separation and concentration of solutes, health care and remediation of environmental pollution. The report provides basic information on radiation processing and promotes experience exchange for further developments of radiation technology. Protocols and procedures of preparation of various stimuli responsive membranes and their actual and perspective applications are described in the report. Public awareness and technology acceptance are other factors to be considered for further dissemination. This publication summarizes the present status and the prospects of this technology

The self-crosslinking smart hyaluronic acid hydrogels as injectable three-dimensional scaffolds for cells culture.

Science.gov (United States)

Bian, Shaoquan; He, Mengmeng; Sui, Junhui; Cai, Hanxu; Sun, Yong; Liang, Jie; Fan, Yujiang; Zhang, Xingdong

2016-04-01

Although the disulfide bond crosslinked hyaluronic acid hydrogels have been reported by many research groups, the major researches were focused on effectively forming hydrogels. However, few researchers paid attention to the potential significance of controlling the hydrogel formation and degradation, improving biocompatibility, reducing the toxicity of exogenous and providing convenience to the clinical operations later on. In this research, the novel controllable self-crosslinking smart hydrogels with in-situ gelation property was prepared by a single component, the thiolated hyaluronic acid derivative (HA-SH), and applied as a three-dimensional scaffold to mimic native extracellular matrix (ECM) for the culture of fibroblasts cells (L929) and chondrocytes. A series of HA-SH hydrogels were prepared depending on different degrees of thiol substitution (ranging from 10 to 60%) and molecule weights of HA (0.1, 0.3 and 1.0 MDa). The gelation time, swelling property and smart degradation behavior of HA-SH hydrogel were evaluated. The results showed that the gelation and degradation time of hydrogels could be controlled by adjusting the component of HA-SH polymers. The storage modulus of HA-SH hydrogels obtained by dynamic modulus analysis (DMA) could be up to 44.6 kPa. In addition, HA-SH hydrogels were investigated as a three-dimensional scaffold for the culture of fibroblasts cells (L929) and chondrocytes cells in vitro and as an injectable hydrogel for delivering chondrocytes cells in vivo. These results illustrated that HA-SH hydrogels with controllable gelation process, intelligent degradation behavior, excellent biocompatibility and convenient operational characteristics supplied potential clinical application capacity for tissue engineering and regenerative medicine. Copyright © 2016 Elsevier B.V. All rights reserved.

Thermo-controlled rheology of electro-assembled polyanionic polysaccharide (alginate) and polycationic thermo-sensitive polymers.

Science.gov (United States)

Niang, Pape Momar; Huang, Zhiwei; Dulong, Virginie; Souguir, Zied; Le Cerf, Didier; Picton, Luc

2016-03-30

Several thermo-sensitive polyelectrolyte complexes were prepared by ionic self-association between an anionic polysaccharide (alginate) and a monocationic copolymer (polyether amine, Jeffamine®-M2005) with a 'Low Critical Solubility Temperature' (LCST). We show that electro-association must be established below the aggregation temperature of the free Jeffamine®, after which the organization of the system is controlled by the thermo-association of Jeffamine® that was previously electro-associated with the alginate. Evidence for this comes primarily from the rheology in the semi-dilute region. Electro- and thermo-associative behaviours are optimal at a pH corresponding to maximum ionization of both compounds (around pH 7). High ionic strength could prevent the electro-association. The reversibility of the transition is possible only at temperatures lower than the LCST of Jeffamine®. Similar behaviour has been obtained with carboxymethyl cellulose (CMC), which suggests that this behaviour can be observed using a range of anionic polyelectrolytes. In contrast, no specific properties have been found for pullulan, which is a neutral polysaccharide. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cell-specific and pH-sensitive nanostructure hydrogel based on chitosan as a photosensitizer carrier for selective photodynamic therapy.

Science.gov (United States)

Belali, Simin; Karimi, Ali Reza; Hadizadeh, Mahnaz

2018-04-15

The major problems of porphyrins as promising materials for photodynamic therapy (PDT) are their low solubility, subsequently aggregation in biological environments, and a lack of tumor selectivity. With this in mind, a chitosan-based hydrogel conjugated with tetrakis(4-aminophenyl)porphyrin (NH 2 -TPP) and 2,4,6-tris(p-formylphenoxy)-1,3,5-triazine (TRIPOD) via Schiff base linkage, functionalized with folate was designed and synthesized as a pH-sensitive, self-healable and injectable targeted PS delivery system. This new hydrogel was characterized by FT-IR, 1 H NMR, SEM, UV-vis, fluorescence spectroscopy and zeta potential. Formation of imine bonds with the aldehyde group of TRIPOD and amine group of NH 2 -TPP and chitosan, as a dynamic connection, was approved by rheological analysis. Spectroscopic characterizations revealed that aggregation of porphyrin in aqueous media was eliminated due to diminished π stacking interaction of porphyrin in 3D cross-linked hydrogel structure. Hydrogel 3D microporous structure efficiently transfers the excitation energy to the porphyrin unit, yielding improvement singlet oxygen releases. Cytotoxicity and phototoxicity analysis of the CS/NH 2 -TPP/FA hydrogels indicating an excellent capability to kill cancer cells selectively and prevent damage to normal cells. This work presents a new and efficient model for the preparation of highly efficient and targeting photosensitizer delivery system. Copyright © 2018. Published by Elsevier B.V.

pH and Glucose Dual-Responsive Injectable Hydrogels with Insulin and Fibroblasts as Bioactive Dressings for Diabetic Wound Healing.

Science.gov (United States)

Zhao, Lingling; Niu, Lijing; Liang, Hongze; Tan, Hui; Liu, Chaozong; Zhu, Feiyan

2017-11-01

pH and glucose dual-responsive injectable hydrogels were prepared through the cross-linking of Schiff's base and phenylboronate ester using phenylboronic-modified chitosan, poly(vinyl alcohol) and benzaldehyde-capped poly(ethylene glycol). Protein drugs and live cells could be incorporated into the hydrogels during the in situ cross-linking, displaying sustained and pH/glucose-triggered drug release from the hydrogels and cell viability and proliferation in the three-dimensional hydrogel matrix as well. Hence, the hydrogels with insulin and fibroblasts were considered as bioactive dressings for diabetic wound healing. A streptozotocin-induced diabetic rat model was used to evaluate the efficacy of hydrogel dressings in wound repair. The results revealed that the incorporation of insulin and L929 in the hydrogels could promote neovascularization and collagen deposition and enhance the wound-healing process of diabetic wounds. Thus, the drug- and cell-loaded hydrogels have promising potential in wound healing as a medicated system for various therapeutic proteins and live cells.

5-FU-hydrogel inhibits colorectal peritoneal carcinomatosis and tumor growth in mice

International Nuclear Information System (INIS)

Wang, Yongsheng; Gong, Changyang; Yang, Li; Wu, Qinjie; Shi, Shuai; Shi, Huashan; Qian, Zhiyong; Wei, Yuquan

2010-01-01

Colorectal peritoneal carcinomatosis (CRPC) is a common form of systemic metastasis of intra-abdominal cancers. Intraperitoneal chemotherapy is a preferable option for colorectal cancer. Here we reported that a new system, 5-FU-loaded hydrogel system, can improve the therapeutic effects of intraperitoneal chemotherapy. A biodegradable PEG-PCL-PEG (PECE) triblock copolymer was successfully synthesized. The biodegradable and temperature sensitive hydrogel was developed to load 5-FU. Methylene blue-loaded hydrogel were also developed for visible observation of the drug release. The effects and toxicity of the 5-FU-hydrogel system were evaluated in a murine CRPC model. The hydrogel system is an injectable flowing solution at ambient temperature and forms a non-flowing gel depot at physiological temperature. 5-FU-hydrogel was subsequently injected into abdominal cavity in mice with CT26 cancer cells peritoneal dissemination. The results showed that the hydrogel delivery system prolonged the release of methylene blue; the 5-FU-hydrogel significantly inhibited the peritoneal dissemination and growth of CT26 cells. Furthermore, intraperitoneal administration of the 5-FU-hydrogel was well tolerated and showed less hematologic toxicity. Our data indicate that the 5-FU-hydrogel system can be considered as a new strategy for peritoneal carcinomatosis, and the hydrogel may provide a potential delivery system to load different chemotherapeutic drugs for peritoneal carcinomatosis of cancers

Novel injectable gellan gum hydrogel composites incorporating Zn- and Sr-enriched bioactive glass microparticles: High-resolution X-ray microcomputed tomography, antibacterial and in vitro testing.

Science.gov (United States)

Douglas, Timothy E L; Dziadek, Michal; Gorodzha, Svetlana; Lišková, Jana; Brackman, Gilles; Vanhoorne, Valérie; Vervaet, Chris; Balcaen, Lieve; Del Rosario Florez Garcia, Maria; Boccaccini, Aldo R; Weinhardt, Venera; Baumbach, Tilo; Vanhaecke, Frank; Coenye, Tom; Bačáková, Lucie; Surmeneva, Maria A; Surmenev, Roman A; Cholewa-Kowalska, Katarzyna; Skirtach, Andre G

2018-06-01

Mineralization of hydrogel biomaterials is desirable to improve their suitability as materials for bone regeneration. In this study, gellan gum (GG) hydrogels were formed by simple mixing of GG solution with bioactive glass microparticles of 45S5 composition, leading to hydrogel formation by ion release from the amorphous bioactive glass microparticles. This resulted in novel injectable, self-gelling composites of GG hydrogels containing 20% bioactive glass. Gelation occurred within 20 min. Composites containing the standard 45S5 bioactive glass preparation were markedly less stiff. X-ray microcomputed tomography proved to be a highly sensitive technique capable of detecting microparticles of diameter approximately 8 μm, that is, individual microparticles, and accurately visualizing the size distribution of bioactive glass microparticles and their aggregates, and their distribution in GG hydrogels. The widely used melt-derived 45S5 preparation served as a standard and was compared with a calcium-rich, sol-gel derived preparation (A2), as well as A2 enriched with zinc (A2Zn5) and strontium (A2Sr5). A2, A2Zn, and A2Sr bioactive glass particles were more homogeneously dispersed in GG hydrogels than 45S5. Composites containing all four bioactive glass preparations exhibited antibacterial activity against methicillin-resistant Staphylococcus aureus. Composites containing A2Zn5 and A2Sr5 bioactive glasses supported the adhesion and growth of osteoblast-like cells and were considerably more cytocompatible than 45S5. All composites underwent mineralization with calcium-deficient hydroxyapatite upon incubation in simulated body fluid. The extent of mineralization appeared to be greatest for composites containing A2Zn5 and 45S5. The results underline the importance of the choice of bioactive glass when preparing injectable, self-gelling composites. Copyright © 2018 John Wiley & Sons, Ltd.

Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

International Nuclear Information System (INIS)

Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat; Amin, Mohd. Cairul Iqbal Mohd

2014-01-01

The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier

Chemical crosslinking of acrylic acid to form biocompatible pH sensitive hydrogel reinforced with cellulose nanocrystals (CNC)

Energy Technology Data Exchange (ETDEWEB)

Lim, Lim Sze; Ahmad, Ishak; Lazim, Mohd Azwani Shah Mat [Faculty of Science and Technology, University Kebangsaan Malaysia, 43600 UKM, Bangi, Selangor (Malaysia); Amin, Mohd. Cairul Iqbal Mohd [Faculty of Pharmacy, University Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur (Malaysia)

2014-09-03

The purpose of this study is to produce a novel pH and temperature sensitive hydrogel, composed of poly(acrylic acid) (PAA) and cellulose nanocrystal (CNC). CNC was extracted from kenaf fiber through a series of alkali and bleaching treatments followed by acid hydrolysis. The PAA was then subjected to chemical cross-linking using the cross-linking agent (N,N-methylenebisacrylamide) with CNC entrapped in PAA matrix. The mixture was casted onto petri dish to obtain disc shape hydrogel. The effects of reaction conditions such as the ratio of PAA and CNC on the swelling behavior of the hydrogel obtained towards pH and temperature were studied. The obtained hydrogel was further subjected to different tests such swelling test for swelling behaviour at different pH and temperature along with scanning electron microscopy (SEM) for morphology analysis. The hydrogel obtained showed excellent pH sensitivity and obtained maximum swelling at pH 7. Besides that, hydrogel obtained showed significant increase in swelling ratio when temperature of swelling medium was increased from 25°C to 37°C. SEM micrograph showed that the pore size of the hydrogel decreases with increase of CNC content proving that the hydrogel structure became more rigid with addition of CNC. The PAA/CNC hydrogel with such excellent sensitivity towards pH and temperature can be developed further as drug carrier.

Injectable hydrogel as stem cell scaffolds from the thermosensitive terpolymer of NIPAAm/AAc/HEMAPCL

Directory of Open Access Journals (Sweden)

Lian S

2012-09-01

Full Text Available Sheng Lian,1Yan Xiao,1 Qingqing Bian,1Yu Xia,2 Changfa Guo,2 Shenguo Wang,2 Meidong Lang11Shanghai Key Laboratory of Advanced Polymeric Materials, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai, People's Republic of China; 2Department of Cardiac Surgery, Zhongshan Hospital, Fudan University and Shanghai Institute of Cardiovascular Diseases, Shanghai, People's Republic of ChinaAbstract: A series of biodegradable thermosensitive copolymers was synthesized by free radical polymerization with N-isopropylacrylamide (NIPAAm, acrylic acid (AAc and macromer 2-hydroxylethyl methacrylate-poly(ε-caprolactone (HEMAPCL. The structure and composition of the obtained terpolymers were confirmed by proton nuclear magnetic resonance spectroscopy, while their molecular weight was measured using gel permeation chromatography. The copolymers were dissolved in phosphate-buffered saline (PBS solution (pH = 7.4 with different concentrations to prepare hydrogels. The lower critical solution temperature (LCST, cloud point, and rheological property of the hydrogels were determined by differential scanning calorimetry, ultraviolet-visible spectrometry, and rotational rheometry, respectively. It was found that LCST of the hydrogel increased significantly with the increasing NIPAAm content, and hydrogel with higher AAc/HEMAPCL ratio exhibited better storage modulus, water content, and injectability. The hydrogels were formed by maintaining the copolymer solution at 37°C. The degradation experiment on the formed hydrogels was conducted in PBS solution for 2 weeks and demonstrated a less than 20% weight loss. Scanning electron microscopy was also used to study the morphology of the hydrogel. The copolymer with NIPAAm/AAc/HEMAPCL ratio of 88:9.6:2.4 was bioconjugated with type I collagen for the purpose of biocompatibility enhancement. In-vitro cytotoxicity

Thermo-driven microcrawlers fabricated via a microfluidic approach

International Nuclear Information System (INIS)

Wang Wei; Yao Chen; Zhang Maojie; Ju Xiaojie; Xie Rui; Chu Liangyin

2013-01-01

A novel thermo-driven microcrawler that can transform thermal stimuli into directional mechanical motion is developed by a simple microfluidic approach together with emulsion-template synthesis. The microcrawler is designed with a thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogel body and a bell-like structure with an eccentric cavity. The asymmetric shrinking–swelling circulation of the microcrawlers enables a thermo-driven locomotion responding to repeated temperature changes, which provides a novel model with symmetry breaking principle for designing biomimetic soft microrobots. The microfluidic approach offers a novel and promising platform for design and fabrication of biomimetic soft microrobots. (paper)

Polymer gel dosimeter with AQUAJOINT® as hydrogel matrix

Science.gov (United States)

Maeyama, Takuya; Ishida, Yasuhiro; Kudo, Yoshihiro; Fukasaku, Kazuaki; Ishikawa, Kenichi L.; Fukunishi, Nobuhisa

2018-05-01

We report a polymer gel dosimeter based on a new gel matrix (AQUAJOINT®) that is a thermo-irreversible hydrogel formed by mixing two types of water-based liquids at room temperature. Normoxic N-vinylpyrrolidone-based polymer gels were prepared with AQUAJOINT® instead of gelatin. This AQUAJOINT®-based gel dosimeter exhibits a 2.5-fold increase in sensitivity over a gelatin-based gel dosimeter and a linear dose-response in the dose range of 0-8 Gy. This gel has heat resistance in a jar and controlled gel properties such as viscoelastic and mechanical characters, which may be useful for deformable polymer gel dosimetry.

Radiation synthesis and characterization of pH-sensitive poly(acrylic acid-co-N-vinyl-2-pyrrolidone) hydrogels

International Nuclear Information System (INIS)

Yang Mingcheng; Zhu Jun; Song Weidong; Song Hongyan; Zhu Chengshen

2006-01-01

Hydrogels are crosslinked, three-dimensional hydrophilic polymer networks that swell but do not dissolve when brought into contact with water. These materials have been investigated extensively for potential applications in the biomedical field because of their similarities to soft tissues and their good tissue and blood compatibility. More specifically, pH-sensitive hydrogels are used for sustained gastro-intestinal drug delivery systems due to the intimacy and extended duration of contact. In this work, pH-sensitive copolymer hydrogels were prepared using acrylic acid and N-vinyl-2-pyrrolidone by γ-ray irradiation at ambient temperature. Effects of dose, monomer concentration, monomer composition, temperature and pH on the swelling ratio (SR) of the copolymer hydrogels were investigated in detail. The results show that SR of the copolymer hydrogels decreases with the monomer concentration and with the increase of absorbed dose. These copolymer hydrogels show good pH-sensitive behavior. These material shows no noticeable change in swelling at lower pH (pH<4) but an abrupt increase in swelling at higher pH (from pH7 to pH9.8). At pH 1.4, the SR of the copolymer hydrogels increases with the temperature. To the contrary, at pH 9.8, the SR of the copolymer hydrogels decreases with the temperature. (authors)

Local application of a gentamicin-loaded thermo-responsive hydrogel allows for fracture healing upon clearance of a high Staphylococcus aureus load in a rabbit model

Directory of Open Access Journals (Sweden)

G-JA ter Boo

2018-03-01

Full Text Available ntibiotic-loaded biomaterials (ALBs have emerged as a potential useful adjunctive antimicrobial measure for the prevention of infection in open fracture care. A biodegradable thermo-responsive poly(N-isopropylacrylamide grafted hyaluronic acid (HApN hydrogel loaded with gentamicin has recently been shown to prevent implant-related infection in a rabbit osteosynthesis model. The primary aim of this study was to determine the influence of this HApN hydrogel on bone healing at an early stage (4 weeks. A rabbit humeral osteotomy model with plating osteosynthesis was used to compare fracture healing in rabbits receiving the hydrogel as compared with control animals. The secondary aim was to observe fracture healing in groups treated with and without antibiotic-loaded hydrogel in the presence of bacterial contamination. In all groups, outcome measures were mechanical stability and histological score, with additional quantitative bacteriology in the inoculated groups. Application of the HApN hydrogel in non-inoculated rabbits did not significantly influence humeral stiffness or histological scores for fracture healing in comparison to controls. In the inoculated groups, animals receiving the bacterial inoculum without hydrogel were culture-positive at euthanasia and found to display lower humeral stiffness values and higher histopathological scores for bacterial presence in comparison with equivalents receiving the gentamicin-loaded HApN hydrogel, which were also infection-free. In summary, our data showed that HApN was an effective antibiotic carrier that did not affect fracture healing. This data supported its suitability for application in fracture care. Addition of osteopromotive compounds could provide further support for accelerating fracture healing in addition to successful infection prophylaxis.

Novel thermal-sensitive hydrogel enhances both humoral and cell-mediated immune responses by intranasal vaccine delivery.

Science.gov (United States)

Wu, Youbin; Wu, Shipo; Hou, Lihua; Wei, Wei; Zhou, Meng; Su, Zhiguo; Wu, Jie; Chen, Wei; Ma, Guanghui

2012-08-01

A novel thermal sensitive hydrogel was formulated with N-[(2-hydroxy-3-trimethylammonium) propyl] chitosan chloride (HTCC) and α, β-glycerophosphate (α, β-GP). A serial of hydrogels containing different amount of GP and HTCC with diverse quarternize degree (QD, 41%, 59%, 79.5%, and 99%) were prepared and characterized by rheological method. The hydrogel was subsequently evaluated for intranasal vaccine delivery with adenovirus based Zaire Ebola virus glycoprotein antigen (Ad-GPZ). Results showed that moderate quarternized HTCC (60% and 79.5%) hydrogel/antigen formulations induced highest IgG, IgG1, and IgG2a antibody titers in serum, as well as mucosal IgA responses in lung wash, which may attributed to the prolonged antigen residence time due to the thermal-sensitivity of this hydrogel. Furthermore, CD8(+) splenocytes for IFN-γ positive cell assay and the release profile of Th1/Th2 type cytokines (IFN-γ, IL-2, IL-10, and IL-4) showed that hydrogel/Ad-GPZ generated an overwhelmingly enhanced Th1 biased cellular immune response. In addition, this hydrogel displayed low toxicity to nasal tissue and epithelial cells even by frequently intranasal dosing of hydrogel. All these results strongly supported this hydrogel as a safe and effective delivery system for nasal immunization. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

Thermo-sensitive nanoparticles for triggered release of siRNA.

Science.gov (United States)

Yang, Zheng; Cheng, Qiang; Jiang, Qian; Deng, Liandong; Liang, Zicai; Dong, Anjie

2015-01-01

Efficient delivery of small interfering RNA (siRNA) is crucially required for cancer gene therapy. Herein, a thermo-sensitive copolymer with a simple structure, poly (ethylene glycol) methyl ether acrylate-b-poly (N-isopropylacrylamide) (mPEG-b-PNIPAM) was developed. A novel kind of thermo-sensitive nanoparticles (DENPs) was constructed for the cold-shock triggered release of siRNA by double emulsion-solvent evaporation method using mPEG-b-PNIPAM and a cationic lipid, 3β [N-(N', N'-dimethylaminoethane)-carbamoyl] cholesterol [DC-Chol]. DENPs were observed by transmission electron microscopy and dynamical light scattering before and after 'cold shock' treatment. The encapsulation efficiency (EE) of siRNA in DENPs, which was measured by fluorescence spectrophotometer was 96.8% while it was significantly reduced to be 23.2% when DC-Chol was absent. DENPs/siRNA NPs exhibited a thermo-sensitive siRNA release character that the cumulatively released amount of siRNA from cold shock was approximately 2.2 folds higher after 7 days. In vitro luciferase silencing experiments indicated that DENPs showed potent gene silencing efficacy in HeLa-Luc cells (HeLa cells steadily expressed luciferase), which was further enhanced by a cold shock. Furthermore, MTT assay showed that cell viability with DENPs/siRNA up to 200 nM remained above 80%. We also observed that most of siRNA was accumulated in kidney mediated by DENPs instead of liver and spleen in vivo experiments. Thus, DENPs as a cold shock responsive quick release model for siRNA or hydrophilic macromolecules delivery provide a new way to nanocarrier design and clinic therapy.

The Co-axial Flow of Injectable Solid Hydrogels with Encapsulated Cells

Science.gov (United States)

Stewart, Brandon; Pochan, Darrin; Sathaye, Sameer

2013-03-01

Hydrogels are quickly becoming an important biomaterial that can be used for the safe, localized injection of cancer drugs, the injection of stem cells into areas of interest or other biological applications. Our peptides can be self-assembled in a syringe where they form a gel, sheared by injection and, once in the body, immediately reform a localized pocket of stiff gel. My project has been designed around looking at the possibility of having a co-axial strand, in which one gel can surround another. This co-axial flow can be used to change the physical properties of our gel during injection, such as stiffening our gel using hyaluronic acid or encapsulating cells in the gel and surrounding the gel with growth medium or other biological factors. Rheology on hyaluron stiffened gels and cells encapsulated in gels was performed for comparison to the results from co-axial flow. Confocal microscopy was used to examine the coaxial gels after flow and to determine how the co-axial nature of the gels is affected by the concentration of peptide.

Investigation on Au-nano incorporated pH-sensitive (itaconic acid/acrylic acid/triethylene glycol) based polymeric biocompatible hydrogels

Energy Technology Data Exchange (ETDEWEB)

Sakthivel, M., E-mail: msakthi81986@gmail.com [Research and Development Centre, Bharathiar University, Coimbatore 641 046, Tamilnadu (India); Department of Chemistry, Ganadipathy Tulsi' s Jain Engineering College, Kaniyambadi, Vellore 632 102, Tamilnadu (India); Franklin, D.S., E-mail: loyolafrank@yahoo.co.in [Department of Chemistry, C. Abdul Hakeem College of Engineering and Technology, Melvisharam 632509, Tamilnadu (India); Sudarsan, S., E-mail: srsudarsan29@gmail.com [Department of Chemistry, Periyar University, Salem 636011, Tamilnadu (India); Chitra, G., E-mail: chitramuralikrishnan@gmail.com [Department of Chemistry, Periyar University, Salem 636011, Tamilnadu (India); Guhanathan, S., E-mail: sai_gugan@yahoo.com [PG & Research Department of Chemistry, Muthurangam Government Arts College, Vellore 632 002, Tamilnadu (India)

2017-06-01

The pH-sensitive gold nano hydrogel based on itaconic acid, acrylic acid and triethylene glycol (GIAT) has been prepared by free radical polymerization viz. organic solventless approach with different monomer ratios. The nature of bonding and structural identification of GIAT hydrogels were characterized by FT-IR spectroscopy. The surface morphology of gold gel was examined using scanning electron microscopy (SEM). In addition, transmission electron microscopy (TEM) was used to identify the size of gold nano particles. The in vitro biocompatibility of GIAT hydrogel has been evaluated in 3T3 fibroblast cell lines. The obtained results show that gold nano particle incorporated hydrogel possess ~ 99% of cell proliferation. Followed by, the impact of gold nano particles on swelling, surface morphology was studied. The consecutive preparation of hydrogel, effect of different pH conditions, and stoichiometry of monomeric units have also been discussed. The degree of swelling was measured in carbonate buffer solutions for 24 h period with varying pH such as 1.2, 6.0, 7.4 and 10.0. The obtained results showed that the stoichiometry of itaconic acid and gold nano particles plays an essential role in modifying the nature of GIAT polymeric hydrogels. In conclusion, promising Au-nano incorporated pH-sensitive bio polymeric hydrogels were prepared and characterized. The unique properties of these Au-nano hydrogel make them attractive use in biomedical applications. - Highlights: • Itaconic acid based hydrogels were developed viz. greener organic solvent less approach. • The enhanced equilibrium swelling at acidic and basic medium was observed for nano-Au-incorporated nano composite hydrogels. • The prepared GIAT hydrogel showed ~ 99% of cell proliferation. • This kind of pH-sensitive polymeric hydrogels may be useful for controlled drug delivery system.

Investigation on Au-nano incorporated pH-sensitive (itaconic acid/acrylic acid/triethylene glycol) based polymeric biocompatible hydrogels

International Nuclear Information System (INIS)

Sakthivel, M.; Franklin, D.S.; Sudarsan, S.; Chitra, G.; Guhanathan, S.

2017-01-01

The pH-sensitive gold nano hydrogel based on itaconic acid, acrylic acid and triethylene glycol (GIAT) has been prepared by free radical polymerization viz. organic solventless approach with different monomer ratios. The nature of bonding and structural identification of GIAT hydrogels were characterized by FT-IR spectroscopy. The surface morphology of gold gel was examined using scanning electron microscopy (SEM). In addition, transmission electron microscopy (TEM) was used to identify the size of gold nano particles. The in vitro biocompatibility of GIAT hydrogel has been evaluated in 3T3 fibroblast cell lines. The obtained results show that gold nano particle incorporated hydrogel possess ~ 99% of cell proliferation. Followed by, the impact of gold nano particles on swelling, surface morphology was studied. The consecutive preparation of hydrogel, effect of different pH conditions, and stoichiometry of monomeric units have also been discussed. The degree of swelling was measured in carbonate buffer solutions for 24 h period with varying pH such as 1.2, 6.0, 7.4 and 10.0. The obtained results showed that the stoichiometry of itaconic acid and gold nano particles plays an essential role in modifying the nature of GIAT polymeric hydrogels. In conclusion, promising Au-nano incorporated pH-sensitive bio polymeric hydrogels were prepared and characterized. The unique properties of these Au-nano hydrogel make them attractive use in biomedical applications. - Highlights: • Itaconic acid based hydrogels were developed viz. greener organic solvent less approach. • The enhanced equilibrium swelling at acidic and basic medium was observed for nano-Au-incorporated nano composite hydrogels. • The prepared GIAT hydrogel showed ~ 99% of cell proliferation. • This kind of pH-sensitive polymeric hydrogels may be useful for controlled drug delivery system.

Optimizing Double-Network Hydrogel for Biomedical Soft Robots.

Science.gov (United States)

Banerjee, Hritwick; Ren, Hongliang

2017-09-01

Double-network hydrogel with standardized chemical parameters demonstrates a reasonable and viable alternative to silicone in soft robotic fabrication due to its biocompatibility, comparable mechanical properties, and customizability through the alterations of key variables. The most viable hydrogel sample in our article shows tensile strain of 851% and maximum tensile strength of 0.273 MPa. The elasticity and strength range of this hydrogel can be customized according to application requirements by simple alterations in the recipe. Furthermore, we incorporated Agar/PAM hydrogel into our highly constrained soft pneumatic actuator (SPA) design and eventually produced SPAs with escalated capabilities, such as larger range of motion, higher force output, and power efficiency. Incorporating SPAs made of Agar/PAM hydrogel resulted in low viscosity, thermos-reversibility, and ultralow elasticity, which we believe can help to combine with the other functions of hydrogel, tailoring a better solution for fabricating biocompatible soft robots.

A wide range and highly sensitive optical fiber pH sensor using polyacrylamide hydrogel

Science.gov (United States)

Pathak, Akhilesh Kumar; Singh, Vinod Kumar

2017-12-01

In the present study we report the fabrication and characterization of no-core fiber sensor (NCFS) using smart hydrogel coating for pH measurement. The no-core fiber (NCF) is stubbed between two single-mode fibers with SMA connector before immobilizing of smart hydrogel. The wavelength interrogation technique is used to calculate the sensitivity of the proposed sensor. The result shows a high sensitivity of 1.94 nm/pH for a wide range of pH values varied from 3 to 10 with a good linear response. In addition to high sensitivity, the fabricated sensor provides a fast response time with a good stability, repeatability and reproducibility.

Development of a multiphysics model to characterize the responsive behavior of urea-sensitive hydrogel as biosensor.

Science.gov (United States)

Goh, K B; Li, Hua; Lam, K Y

2017-05-15

A remarkable feature of biomaterials is their ability to deform in response to certain external bio-stimuli. Here, a novel biochemo-electro-mechanical model is developed for the numerical characterization of the urea-sensitive hydrogel in response to the external stimulus of urea. The urea sensitivity of the hydrogel is usually characterized by the states of ionization and denaturation of the immobilized urease, as such the model includes the effect of the fixed charge groups and temperature coupled with pH on the activity of the urease. Therefore, a novel rate of reaction equation is proposed to characterize the hydrolysis of urea that accounts for both the ionization and denaturation states of the urease subject to the environmental conditions. After examination with the published experimental data, it is thus confirmed that the model can characterize well the responsive behavior of the urea-sensitive hydrogel subject to the urea stimulus, including the distribution patterns of the electrical potential and pH of the hydrogel. The results point to an innovative means for generating electrical power via the enzyme-induced pH and electrical potential gradients, when the hydrogel comes in contact with the urea-rich solution, such as human urine. Copyright © 2017 Elsevier B.V. All rights reserved.

Radiation-induced synthesis and swelling properties of p(2-hydroxyethyl methacrylate-co-itaconic acid-co-oligo(ethylene glycol) acrylate) copolymeric hydrogels

International Nuclear Information System (INIS)

Micic, M.; Suljovrujic, E.

2011-01-01

Complete text of publication follows. Since it is presumed that by incorporation of pH-responsive (IA) and temperature-responsive (OEGA) co-monomers it is possible to prepare P(HEMA-co-IA-co-OEGA) hydrogels with duel (pH and thermo) responsiveness, the main purpose of this paper is to investigate the influence of different mole fractions of IA and especially OEGA on the diversity of the swelling properties of obtained hydrogels. For that reason, a series of copolymeric hydrogels with different mole ratios of 2-hydroxyethyl methacrylate (HEMA), itaconic acid (IA) and oligo(ethylene glycol) acrylates (OEGA) was synthesized by gamma radiation. The obtained hydrogels were characterized by swelling studies in the wide pH (2.2-9.0) and temperature range (25-70 deg C), confirming dual (pH and thermo) responsiveness and a large variation in swelling capability. It was observed that the equilibrium swelling of P(HEMA-co-IA-co-OEGA) hydrogels, for a constant amount of IA, increases progressively with increasing in OEGA share. On the other hand, the dissociation of carboxyl (-COOH) groups from IA occurs at pH > 4; therefore, small mole fractions of IA render good pH sensitivity and a large increase in the swelling capacity of these hydrogels at higher pH values. Additional characterization of structure and properties was conducted by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and mechanical measurements, confirming that the inherent properties of the P(HEMA-co-IA-co-OEGA) hydrogels can be significantly tuned by variation in their composition. According to all presented, it seems that the obtained copolymeric hydrogels can be a beneficial synergetic combination for controlled delivery of bioactive molecules such as drugs, nucleic acids, peptides, and proteins.

Recovery of oxidative stress-induced damage in Cisd2-deficient cardiomyocytes by sustained release of ferulic acid from injectable hydrogel.

Science.gov (United States)

Cheng, Yung-Hsin; Lin, Feng-Huei; Wang, Chien-Ying; Hsiao, Chen-Yuan; Chen, Hung-Ching; Kuo, Hsin-Yu; Tsai, Ting-Fen; Chiou, Shih-Hwa

2016-10-01

Aging-related oxidative stress is considered a major risk factor of cardiovascular diseases (CVD) and could be associated with mitochondrial dysfunction and reactive oxygen species (ROS) overproduction. Cisd2 is an outer mitochondrial membrane protein and plays an important role in controlling the lifespan of mammals. Ferulic acid (FA), a natural antioxidant, is able to improve cardiovascular functions and inhibit the pathogenetic CVD process. However, directly administering therapeutics with antioxidant molecules is challenging because of stability and bioavailability issues. In the present study, thermosensitive chitosan-gelatin-based hydrogel containing FA was used to treat Cisd2-deficient (Cisd2(-/-)) cardiomyocytes (CM) derived from induced pluripotent stem cells of Cisd2(-/-) murine under oxidative stress. The results revealed that the developed hydrogel could provide a sustained release of FA and increase the cell viability. Post-treatment of FA-loaded hydrogel effectively decreased the oxidative stress-induced damage in Cisd2(-/-) CM via increasing catalase activity and decreasing endogenous reactive oxygen species (ROS) production. The in vivo biocompatibility of FA-loaded hydrogel was confirmed in subcutaneously injected rabbits and intramyocardially injected Cisd2(-/-) mice. These results suggest that the thermosensitive FA-loaded hydrogel could rescue Cisd2(-/-) CM from oxidative stress-induced damage and may have potential applications in the future treatment of CVD. Copyright © 2016 Elsevier Ltd. All rights reserved.

Design and synthesis study of the thermo-sensitive poly (N-vinylpyrrolidone-b- N, N-diethylacrylamide).

Science.gov (United States)

Zhang, Xiayun; Yang, Zhongduo; Xie, Dengmin; Liu, Donglei; Chen, Zhenbin; Li, Ke; Li, Zhizhong; Tichnell, Brandon; Liu, Zhen

2018-01-01

The reversible addition fragmentation chain transfer (RAFT) polymerization method was adopted here to prepare a series of thermo-sensitive copolymers, poly (N,N-diethyl- acrylamide-b-N-vinylpyrrolidone). Their structures, molecular weight distribution and temperature sensitivity performances were characterized by the nuclear magnetic resonance ( 1 HNMR), the gel permeation chromatography (GPC) and the fluorescence spectrophotometer, respectively. It has been identified that the synthesis reaction of the block copolymer was living polymerization. The thermo-sensitivity study suggested that N-vinylpyrrolidone (NVP), played a key role on the lower critical solution temperature (LCST) performance.

3D Printing of Thermo-Responsive Methylcellulose Hydrogels for Cell-Sheet Engineering.

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Cochis, Andrea; Bonetti, Lorenzo; Sorrentino, Rita; Contessi Negrini, Nicola; Grassi, Federico; Leigheb, Massimiliano; Rimondini, Lia; Farè, Silvia

2018-04-10

A possible strategy in regenerative medicine is cell-sheet engineering (CSE), i.e., developing smart cell culture surfaces from which to obtain intact cell sheets (CS). The main goal of this study was to develop 3D printing via extrusion-based bioprinting of methylcellulose (MC)-based hydrogels. Hydrogels were prepared by mixing MC powder in saline solutions (Na₂SO₄ and PBS). MC-based hydrogels were analyzed to investigate the rheological behavior and thus optimize the printing process parameters. Cells were tested in vitro on ring-shaped printed hydrogels; bulk MC hydrogels were used for comparison. In vitro tests used murine embryonic fibroblasts (NIH/3T3) and endothelial murine cells (MS1), and the resulting cell sheets were characterized analyzing cell viability and immunofluorescence. In terms of CS preparation, 3D printing proved to be an optimal approach to obtain ring-shaped CS. Cell orientation was observed for the ring-shaped CS and was confirmed by the degree of circularity of their nuclei: cell nuclei in ring-shaped CS were more elongated than those in sheets detached from bulk hydrogels. The 3D printing process appears adequate for the preparation of cell sheets of different shapes for the regeneration of complex tissues.

3D Printing of Thermo-Responsive Methylcellulose Hydrogels for Cell-Sheet Engineering

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Andrea Cochis

2018-04-01

Full Text Available A possible strategy in regenerative medicine is cell-sheet engineering (CSE, i.e., developing smart cell culture surfaces from which to obtain intact cell sheets (CS. The main goal of this study was to develop 3D printing via extrusion-based bioprinting of methylcellulose (MC-based hydrogels. Hydrogels were prepared by mixing MC powder in saline solutions (Na2SO4 and PBS. MC-based hydrogels were analyzed to investigate the rheological behavior and thus optimize the printing process parameters. Cells were tested in vitro on ring-shaped printed hydrogels; bulk MC hydrogels were used for comparison. In vitro tests used murine embryonic fibroblasts (NIH/3T3 and endothelial murine cells (MS1, and the resulting cell sheets were characterized analyzing cell viability and immunofluorescence. In terms of CS preparation, 3D printing proved to be an optimal approach to obtain ring-shaped CS. Cell orientation was observed for the ring-shaped CS and was confirmed by the degree of circularity of their nuclei: cell nuclei in ring-shaped CS were more elongated than those in sheets detached from bulk hydrogels. The 3D printing process appears adequate for the preparation of cell sheets of different shapes for the regeneration of complex tissues.

New perspectives in cell delivery systems for tissue regeneration: natural-derived injectable hydrogels.

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Munarin, Fabiola; Petrini, Paola; Bozzini, Sabrina; Tanzi, Maria Cristina

2012-09-27

Natural polymers, because of their biocompatibility, availability, and physico-chemical properties have been the materials of choice for the fabrication of injectable hydrogels for regenerative medicine. In particular, they are appealing materials for delivery systems and provide sustained and controlled release of drugs, proteins, gene, cells, and other active biomolecules immobilized.In this work, the use of hydrogels obtained from natural source polymers as cell delivery systems is discussed. These materials were investigated for the repair of cartilage, bone, adipose tissue, intervertebral disc, neural, and cardiac tissue. Papers from the last ten years were considered, with a particular focus on the advances of the last five years. A critical discussion is centered on new perspectives and challenges in the regeneration of specific tissues, with the aim of highlighting the limits of current systems and possible future advancements.

Synthesis, characterization and rheological behavior of pH sensitive poly(acrylamide-co-acrylic acid hydrogels

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Seddiki Nesrinne

2017-05-01

Results indicated that the strong interaction in the hydrogels resulted in the formation of a more stable copolymer. The single glass transition temperature (Tg in sample suggested that the two polymers into the hydrogel have a good miscibility. The elastic modulus (G′ and linear viscoelastic region increased with increase in PAAc concentration. The oscillation time sweep study of the hydrogels exhibited a flat G′ indicating a stable structure and good mechanical strength. In the swelling measurements, the gels exhibited appreciable water uptake and were highly sensitive to pH environment. So the poly(AAm-co-AAc hydrogel will have promising application in pharmaceutical use and in biomaterials.

High-water-content mouldable polyvinyl alcohol-borax hydrogels reinforced by well-dispersed cellulose nanoparticles: dynamic rheological properties and hydrogel formation mechanism.

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Han, Jingquan; Lei, Tingzhou; Wu, Qinglin

2014-02-15

Cellulose nanoparticle (CNP) reinforced polyvinyl alcohol-borax (PB) hydrogels were produced via a facile approach in an aqueous system. The effects of particle size, aspect ratio, crystal structure, and surface charge of CNPs on the rheological properties of the composite hydrogels were investigated. The rheological measurements confirmed the incorporation of well-dispersed CNPs to PB system significantly enhanced the viscoelasticity and stiffness of hydrogels. The obtained free-standing, high elasticity and mouldable hydrogels exhibited self-recovery under continuous step strain and thermo-reversibility under temperature sweep. With the addition of cellulose I nanofibers, a 19-fold increase in the high-frequency plateau of storage modulus was obtained compared with that of the pure PB. CNPs acted as multifunctional crosslinking agents and nanofillers to physically and chemically bridge the 3D network hydrogel. The plausible mechanism for the multi-complexation between CNPs, polyvinyl alcohol and borax was proposed to understand the relationship between the 3D network and hydrogel properties. Copyright © 2013 Elsevier Ltd. All rights reserved.

Poly(N-isopropylacrylamide) hydrogel-based shape-adjustable polyimide films triggered by near-human-body temperature.

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Huanqing Cui; Xuemin Du; Juan Wang; Tianhong Tang; Tianzhun Wu

2016-08-01

Hydrogel-based shape-adjustable films were successfully fabricated via grafting poly(N-isopropylacrylamide) (PNIPAM) onto one side of polyimide (PI) films. The prepared PI-g-PNIPAM films exhibited rapid, reversible, and repeatable bending/unbending property by heating to near-human-body temperature (37 °C) or cooling to 25 °C. The excellent property of PI-g-PNIPAM films resulted from a lower critical solution temperature (LCST) of PNIPAM at about 32 °C. Varying the thickness of PNIPAM hydrogel layer regulated the thermo-responsive shape bending degree and response speed of PI-g-PNIPAM films. The thermo-induced shrinkage of hydrogel layers can tune the curvature of PI films, which have potential applications in the field of wearable and implantable devices.

Design of multimodal degradable hydrogels for controlled therapeutic delivery

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Kharkar, Prathamesh Madhav

Hydrogels are of growing interest for the delivery of therapeutics to specific sites in the body. For localized drug delivery, hydrophilic polymeric precursors often are laden with bioactive moieties and then directly injected to the site of interest for in situ gel formation. The release of physically entrapped cargo is dictated by Fickian diffusion, degradation of the drug carrier, or a combination of both. The goal of this work was to design and characterize degradable hydrogel formulations that are responsive to multiple biologically relevant stimuli for degradation-mediated delivery of cargo molecules such as therapeutic proteins, growth factors, and immunomodulatory agents. We began by demonstrating the use of cleavable click linkages formed by Michael-type addition reactions in conjunction with hydrolytically cleavable functionalities for the degradation of injectable hydrogels by endogenous stimuli for controlled protein release. Specifically, the reaction between maleimides and thiols was utilized for hydrogel formation, where thiol selection dictates the degradability of the resulting linkage under thiol-rich reducing conditions. Relevant microenvironments where degradation would occur in vivo include those rich in glutathione (GSH), a tripeptide that is found at elevated concentrations in carcinoma tissues. Degradation of the hydrogels was monitored with rheometry and volumetric swelling measurements. Arylthiol-based thioether succinimide linkages underwent degradation via click cleavage and thiol exchange reaction in the presence of GSH and via ester hydrolysis, whereas alkylthiol-based thioether succinimide linkages only undergo degradation by only ester hydrolysis. The resulting control over the degradation rate within a reducing microenvironment resulted in 2.5 fold differences in the release profile of the model protein, a fluorescently-labeled bovine serum albumin, from dually degradable hydrogels compared to non-degradable hydrogels, where the

Morphing hydrogel patterns by thermo-reversible fluorescence switching.

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Bat, Erhan; Lin, En-Wei; Saxer, Sina; Maynard, Heather D

2014-07-01

Stimuli responsive surfaces that show reversible fluorescence switching behavior in response to temperature changes were fabricated. Oligo(ethylene glycol) methacrylate thermoresponsive polymers with amine end-groups were prepared by atom transfer radical polymerization (ATRP). The polymers were patterned on silicon surfaces by electron beam (e-beam) lithography, followed by conjugation of self-quenching fluorophores. Fluorophore conjugated hydrogel thin films were bright when the gels were swollen; upon temperature-induced collapse of the gels, self-quenching of the fluorophores led to significant attenuation of fluorescence. Importantly, the fluorescence was regained when the temperature was cooled. The fluorescence switching behavior of the hydrogels for up to ten cycles was investigated and the swelling-collapse was verified by atomic force microscopy. Morphing surfaces that change shape several times upon increase in temperature were obtained by patterning multiple stimuli responsive polymers. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

MMP-sensitive PEG diacrylate hydrogels with spatial variations in matrix properties stimulate directional vascular sprout formation.

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Michael V Turturro

Full Text Available The spatial presentation of immobilized extracellular matrix (ECM cues and matrix mechanical properties play an important role in directed and guided cell behavior and neovascularization. The goal of this work was to explore whether gradients of elastic modulus, immobilized matrix metalloproteinase (MMP-sensitivity, and YRGDS cell adhesion ligands are capable of directing 3D vascular sprout formation in tissue engineered scaffolds. PEGDA hydrogels were engineered with mechanical and biofunctional gradients using perfusion-based frontal photopolymerization (PBFP. Bulk photopolymerized hydrogels with uniform mechanical properties, degradation, and immobilized biofunctionality served as controls. Gradient hydrogels exhibited an 80.4% decrease in elastic modulus and a 56.2% decrease in immobilized YRGDS. PBFP hydrogels also demonstrated gradients in hydrogel degradation with degradation times ranging from 10-12 hours in the more crosslinked regions to 4-6 hours in less crosslinked regions. An in vitro model of neovascularization, composed of co-culture aggregates of endothelial and smooth muscle cells, was used to evaluate the effect of these gradients on vascular sprout formation. Aggregate invasion in gradient hydrogels occurred bi-directionally with sprout alignment observed in the direction parallel to the gradient while control hydrogels with homogeneous properties resulted in uniform invasion. In PBFP gradient hydrogels, aggregate sprout length was found to be twice as long in the direction parallel to the gradient as compared to the perpendicular direction after three weeks in culture. This directionality was found to be more prominent in gradient regions of increased stiffness, crosslinked MMP-sensitive peptide presentation, and immobilized YRGDS concentration.

Radiation preparation of drug carriers based on poly(N-isopropylacrylamide) hydrogels, their loading capacities and controlled release rates for dexamethasone and tegafur

International Nuclear Information System (INIS)

Hoang Dang Sang; Nguyen Van Binh; Tran Bang Diep; Nguyen Thi Thom; Hoang Phuong Thao; Pham Duy Duong; Tran Minh Quynh

2015-01-01

Thermo-sensitive hydrogels have great potential in some applications. In order to use as the drug delivery systems, the hydrogels should be biocompatibility. New polymers with more biocompatibility and better biodegradability, and environmental friendly crosslinking agents would be necessary for the successful drug carriers. Poly (N-isopropylacrylamide-co-dimethylacrylamide) based hydrogels have been prepared from the admixture solutions of N-isopropylacrylamide (NIPA) and N,N’-dimethyl acrylamide (DMA) by radiation copolymerization and crosslinking at radiation dose of 20 kGy as reported in our previous study. Water swelling behaviour of the resulting hydrogels were much depended on their nature such as initial ratio of NIPA and DMA. The drug-loaded hydrogels were prepared by merging hydrogel in the solutions containing corresponding drugs. Loading capacity of the hydrogels were about 48.6 and 95.7 mg per g dried hydrogel for dexamethasone and tegafur. The release studies showed that the presence of ions in simulated body fluid and temperature of the solution much affecting to in vitro release behaviors of hydrogels for dexamethasone and tegafur. The release rates were fast for both drug models. The result also revealed that these drug carriers were biocompatibility without skin irritation, suggested the drug-loaded hydrogels may be used as controlled release drug delivery systems. (author)

Quality of life after periurethral injection with polyacrylamide hydrogel for stress urinary incontinence.

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Trutnovsky, Gerda; Tamussino, Karl; Greimel, Elfriede; Bjelic-Radisic, Vesna

2011-03-01

The purpose of this observational study was to examine the effect of periurethral injections with polyacrylamide hydrogel (PAHG) on quality of life (QoL) in selected patients with stress urinary incontinence (SUI). Fifty-four women with comorbidities or other reasons precluding other surgery received PAHG for SUI. Patient-reported outcomes were assessed with the "Incontinence Outcome Questionnaire" (IOQ) 9 months postoperatively. The IOQ is a 27-item, condition-specific instrument that assesses patient-reported outcomes after incontinence surgery. Forty-two women (78%) completed the questionnaire. Responses ranged from considerable (40%) and slight improvement (21%) to no change (29%) and worsening of symptoms (10%). Periurethral injections with PAHG are likely to provide relief of symptoms and improvement in QoL.

Peritoneal adhesion prevention with a biodegradable and injectable N,O-carboxymethyl chitosan-aldehyde hyaluronic acid hydrogel in a rat repeated-injury model

Science.gov (United States)

Song, Linjiang; Li, Ling; He, Tao; Wang, Ning; Yang, Suleixin; Yang, Xi; Zeng, Yan; Zhang, Wenli; Yang, Li; Wu, Qinjie; Gong, Changyang

2016-11-01

Postoperative peritoneal adhesion is one of the serious issues because it induces severe clinical disorders. In this study, we prepared biodegradable and injectable hydrogel composed of N,O-carboxymethyl chitosan (NOCC) and aldehyde hyaluronic acid (AHA), and assessed its anti-adhesion effect in a rigorous and severe recurrent adhesion model which is closer to clinical conditions. The flexible hydrogel, which gelated in 66 seconds at 37 °C, was cross-linked by the schiff base derived from the amino groups of NOCC and aldehyde groups in AHA. In vitro cytotoxicity test showed the hydrogel was non-toxic. In vitro and in vivo degradation examinations demonstrated the biodegradable and biocompatibility properties of the hydrogel. The hydrogel discs could prevent the invasion of fibroblasts, whereas fibroblasts encapsulated in the porous 3-dimensional hydrogels could grow and proliferate well. Furthermore, the hydrogel was applied to evaluate the anti-adhesion efficacy in a more rigorous recurrent adhesion model. Compared with normal saline group and commercial hyaluronic acid (HA) hydrogel, the NOCC-AHA hydrogel exhibited significant reduction of peritoneal adhesion. Compared to control group, the blood and abdominal lavage level of tPA was increased in NOCC-AHA hydrogel group. These findings suggested that NOCC-AHA hydrogel had a great potential to serve as an anti-adhesion candidate.

Preparation of pH-sensitive poly(ethylene oxide) hydrogels grafted by γ-ray irradiation and their applications for drug delivery system

International Nuclear Information System (INIS)

Nho, Y.-C.; Kang, P.-H.; Lim, Y.-M.; Kuk, I.-H.

2006-01-01

Hydrogels are three-dimensional networks of hydrophilic polymers held together by crosslinks of covalent bonds or ionic bonds and secondary forces in the form of hydrogen bonds or hydrophobic interactions. Environmentally sensitive hydrogels have an enormous potential for various applications. Either pH-sensitive and/or temperature- sensitive hydrogels can be used for a site-specific controlled drug delivery. Especially, pH-sensitive hydrogels have been most frequently used to develop controlled release formulations for oral administration. All the pH-sensitive hydrogels contain pendent acidic, for example carboxylic and sulfonic acids, or basic, for example ammonium salts, groups that either accept or release protons in response to changes in environmental pH[3-5]. These ionic hydrogels are the swollen polymer networks which show sudden or gradual changes in their dynamic and equilibrium swelling behavior as a result of changing the external pH. In these gels, ionization occurs when the pH of the environment is above the pKa of the ionizable group . As the degree of ionization increases (pH increase in the system), the number of fixed charges increases, resulting in increased electrostatic repulsions between the chains. Irradiation, especially if combined with simultaneous sterilization of the product, is a very convenient tool for the synthesis of hydrogels. Radiation processing has many advantages over other conventional methods. For initiation processes, radiation differs from chemical initiation. In radiation processing, no catalysts or additives are needed to initiate the reaction. The advantages of the radiation methods are that they are relatively simple, and moreover, the degree of crosslinking, which strongly determines the extent of swelling in hydrogels, can be controlled easily by varying the absorbed dose. Therefore, these methods are found to be very useful in preparing hydrogels for medical applications, where even a small contamination is

Injectable Nanocurcumin-Formulated Chitosan-g-Pluronic Hydrogel Exhibiting a Great Potential for Burn Treatment

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Le Hang Dang

2018-01-01

Full Text Available Burn wound healing is a complex multifactorial process that relies on coordinated signaling molecules to succeed. Curcumin is believed to be a potent antioxidant and anti-inflammatory agent; therefore, it can prevent the prolonged presence of oxygen free radicals which is a significant factor causing inhabitation of optimum healing process. This study describes an extension of study about the biofunctional nanocomposite hydrogel platform that was prepared by using curcumin and an amphiphilic chitosan-g-pluronic copolymer specialized in burn wound healing application. This formular (nCur-CP, nanocomposite hydrogel was a free-flowing sol at ambient temperature and instantly converted into a nonflowing gel at body temperature. In addition, the storage study determined the great stability level of nCur-CP in long time using UV-Vis and DLS. Morphology and distribution of nCur in its nanocomposite hydrogels were observed by SEM and TEM, respectively. In vitro studies suggested that nCur-CP exhibited well fibroblast proliferation and ability in antimicrobacteria. Furthermore, second- and third-degree burn wound models were employed to evaluate the in vivo wound healing activity of the nCur-CP. In the second-degree wound model, the nanocomposite hydrogel group showed a higher regenerated collagen density and thicker epidermis layer formation. In third degree, the nCur-CP group also exhibited enhancement of wound closure. Besides, in both models, the nanocomposite material-treated groups showed higher collagen content, better granulation, and higher wound maturity. Histopathologic examination also implied that the nanocomposite hydrogel based on nanocurcumin and chitosan could enhance burn wound repair. In conclusion, the biocompatible and injectable nanocomposite scaffold might have great potential to apply for wound healing.

1,3,5-Triazine-2,4,6-tribenzaldehyde derivative as a new crosslinking agent for synthesis of pH-thermo dual responsive chitosan hydrogels and their nanocomposites: Swelling properties and drug release behavior.

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Karimi, Ali Reza; Tarighatjoo, Mahsa; Nikravesh, Golara

2017-12-01

In this work, 1,3,5-triazine-2,4,6-tribenzaldehyde was synthesized and chosen as the cross-linking agent for preparation of novel thermo- and pH-responsive hydrogels based on chitosan. The cross-linking proceeds through formation of imine bond by reaction of amino groups of chitosan with aldehyde groups of the cross-linker. The various amounts (6, 10, 14% w/w) of the cross-linker were used with respect to chitosan to produce three 1,3,5-triazine-2,4,6-tribenzaldehyde cross-linked chitosans. Then, their hydrogel nanocomposites were prepared by crosslinking of chitosan with 1,3,5-triazine-2,4,6-tribenzaldehyde in the presence of 0.1% and 0.3% (w/w) multi-walled carbon nanotubes (MWCNTs). The structure and properties of the hydrogels and their nanocomposites were characterized by FT-IR, 1 H NMR and scanning electron microscopy (SEM). The swelling behavior of prepared hydrogels and their nanocomposites at different pHs and temperatures was investigated. The results showed that they exhibit a pH and temperature-responsive swelling ratio. The swelling behavior of the prepared chitosan hydrogels was strongly dependent on the amounts of cross-linker and MWCNTs. In vitro controlled release behavior of metronidazole model drug was studied with prepared hydrogels and nanocomposite hydrogels. The pH, temperature and wt% of MWCNTs were found to strongly influence the drug release behavior of the hydrogels. Copyright © 2017 Elsevier B.V. All rights reserved.

Sensitivity analyses of biodiesel thermo-physical properties under diesel engine conditions

DEFF Research Database (Denmark)

Cheng, Xinwei; Ng, Hoon Kiat; Gan, Suyin

2016-01-01

This reported work investigates the sensitivities of spray and soot developments to the change of thermo-physical properties for coconut and soybean methyl esters, using two-dimensional computational fluid dynamics fuel spray modelling. The choice of test fuels made was due to their contrasting s...

Dextran based highly conductive hydrogel polysulfide electrolyte for efficient quasi-solid-state quantum dot-sensitized solar cells

International Nuclear Information System (INIS)

Chen, Hong-Yan; Lin, Ling; Yu, Xiao-Yun; Qiu, Kang-Qiang; Lü, Xian-Yong; Kuang, Dai-Bin; Su, Cheng-Yong

2013-01-01

Highlights: ► Dextran based hydrogel is first used to prepare quasi-solid-state polysulfide electrolyte for quantum dot-sensitized solar cells. ► The ion conductivity of hydrogel electrolyte shows almost the same value as the liquid electrolyte. ► The liquid state at elevated temperature of hydrogel electrolyte allows for a good contact between electrolyte and CdS/CdSe co-sensitized TiO 2 photoanode. ► The hydrogel electrolyte based cell exhibits slightly lower power conversion efficiency than that of liquid electrolyte based cell. ► The dynamic electron transfer mechanism in hydrogel electrolyte based cell is examined in detail by EIS and CIMPS/IMVS. -- Abstract: Highly conductive hydrogel polysulfide electrolyte is first fabricated using dextran as gelator and used as quasi-solid-state electrolyte for quantum dot-sensitized solar cells (QDSSCs). The hydrogel electrolyte with gelator concentration of 15 wt% shows almost the same conductivity as the liquid one. Moreover, its liquid state at elevated temperature allow for the well penetration into the pores in electrodeposited CdS/CdSe co-sensitized TiO 2 photoanode. This gel electrolyte based QDSSC exhibits power conversion efficiency (η) of 3.23% under AG 1.5 G one sun (100 mW cm −2 ) illumination, slightly lower than that of liquid electrolyte based cell (3.69%). The dynamic electron transfer mechanism of the gel and liquid electrolyte based QDSSC are examined by electrochemical impedance spectroscopy (EIS) and controlled intensity modulated photocurrent/photovoltage spectroscopy (CIMPS/IMVS). It is found that the electron transport in gel electrolyte based cell is much faster than the liquid electrolyte based cell but it tends to recombine more easily than the latter. However, these differences fade away with increasing the light intensity, showing declining electron collection efficiency at higher light intensity illumination. As a result, a conversion efficiency of 4.58% is obtained for the gel

Hydrogel injection reduces rectal toxicity after radiotherapy for localized prostate cancer

Energy Technology Data Exchange (ETDEWEB)

Pinkawa, Michael; Berneking, Vanessa; Koenig, Liane; Frank, Dilini; Bretgeld, Marilou; Eble, Michael J. [RWTH Aachen University, Department of Radiation Oncology, Aachen (Germany)

2017-01-15

Injection of a hydrogel spacer before prostate cancer radiotherapy (RT) is known to reduce the dose to the rectal wall. Clinical results from the patient's perspective are needed to better assess a possible benefit. A group of 167 consecutive patients who received prostate RT during the years 2010 to 2013 with 2-Gy fractions up to 76 Gy (without hydrogel, n = 66) or 76-80 Gy (with hydrogel, n = 101) were included. The numbers of interventions resulting from bowel problems during the first 2 years after RT were compared. Patients were surveyed prospectively before RT, at the last day of RT, and at a median of 2 and 17 months after RT using a validated questionnaire (Expanded Prostate Cancer Index Composite). Baseline patient characteristics were well balanced. Treatment for bowel symptoms (0 vs. 11 %; p < 0.01) and endoscopic examinations (3 vs. 19 %; p < 0.01) were performed less frequently with a spacer. Mean bowel function scores did not change for patients with a spacer in contrast to patients without a spacer (mean decrease of 5 points) >1 year after RT in comparison to baseline, with 0 vs. 12 % reporting a new moderate/big problem with passing stools (p < 0.01). Statistically significant differences were found for the items ''loose stools'', ''bloody stools'', ''painful bowel movements'' and ''frequency of bowel movements''. Spacer injection is associated with a significant benefit for patients after prostate cancer RT. (orig.) [German] Bei der Radiotherapie (RT) des Prostatakarzinoms kann die Dosis an der Rektumwand durch die Injektion eines Hydrogelabstandhalters gesenkt werden. Klinische Ergebnisse aus der Sicht des Patienten sind zur Einschaetzung eines moeglichen Vorteils erforderlich. Eine Gruppe von 167 konsekutiven Patienten, die in den Jahren 2010-2013 eine Prostata-RT mit Einzeldosen von 2 bis 76 Gy (ohne Hydrogel, n = 66) bzw. 76-80 Gy (mit Hydrogel, n = 101

Nerve Cells Decide to Orient inside an Injectable Hydrogel with Minimal Structural Guidance.

Science.gov (United States)

Rose, Jonas C; Cámara-Torres, María; Rahimi, Khosrow; Köhler, Jens; Möller, Martin; De Laporte, Laura

2017-06-14

Injectable biomaterials provide the advantage of a minimally invasive application but mostly lack the required structural complexity to regenerate aligned tissues. Here, we report a new class of tissue regenerative materials that can be injected and form an anisotropic matrix with controlled dimensions using rod-shaped, magnetoceptive microgel objects. Microgels are doped with small quantities of superparamagnetic iron oxide nanoparticles (0.0046 vol %), allowing alignment by external magnetic fields in the millitesla order. The microgels are dispersed in a biocompatible gel precursor and after injection and orientation are fixed inside the matrix hydrogel. Regardless of the low volume concentration of the microgels below 3%, at which the geometrical constrain for orientation is still minimum, the generated macroscopic unidirectional orientation is strongly sensed by the cells resulting in parallel nerve extension. This finding opens a new, minimal invasive route for therapy after spinal cord injury.

Analysis of pH Sensitive Hydrogel Coating Effect to Fiber Bragg Grating Properties for pH Sensor Application

Science.gov (United States)

Yulianti, Ian; Supa'at, Abu Sahmah M.; Idrus, Sevia M.; Kurdi, Ojo

2011-12-01

This paper demonstrates the analysis of fiber Bragg grating properties due to hydrogel coating swelling effect. The modeling was done by simulating the hydrogel swelling behavior, and then carried out strain and stress analysis induced on the fiber due to hydrogel expansion. Meshless numerical method was adopted to solve the Poison Nernst Planck equation coupled to mechanical equation to simulate the hydrogel swelling. The hydrogel coating thickness was varied for 4 values, namely 30 μm, 40 μm, 50 μm and 60 μm. The strain and stress analysis were done numerically using finite element method. The results show that the strain on the fiber increases as the hydrogel coating thickness increased. The increase of hydrogel thickness results in the improvement of sensor sensitivity at the expense of stress value.

Injectable Shear-Thinning CaSO4/FGF-18-Incorporated Chitin-PLGA Hydrogel Enhances Bone Regeneration in Mice Cranial Bone Defect Model.

Science.gov (United States)

Sivashanmugam, A; Charoenlarp, Pornkawee; Deepthi, S; Rajendran, Arunkumar; Nair, Shantikumar V; Iseki, Sachiko; Jayakumar, R

2017-12-13

For craniofacial bone regeneration, shear-thinning injectable hydrogels are favored over conventional scaffolds because of their improved defect margin adaptability, easier handling, and ability to be injected manually into deeper tissues. The most accepted method, after autografting, is the use of recombinant human bone morphogenetic protein-2 (BMP-2); however, complications such as interindividual variations, edema, and poor cost-efficiency in supraphysiological doses have been reported. The endogenous synthesis of BMP-2 is desirable, and a molecule which induces this is fibroblast growth factor-18 (FGF-18) because it can upregulate the BMP-2 expression  by supressing noggin. We developed a chitin-poly(lactide-co-glycolide) (PLGA) composite hydrogel by regeneration chemistry and then incorporated CaSO 4 and FGF-18 for this purpose. Rheologically, a 7-fold increase in the elastic modulus was observed in the CaSO 4 -incorporated chitin-PLGA hydrogels as compared to the chitin-PLGA hydrogel. Shear-thinning Herschel-Bulkley fluid nature was observed for both hydrogels. Chitin-PLGA/CaSO 4 gel showed sustained release of FGF-18. In vitro osteogenic differentiation showed an enhanced alkaline phosphatase (ALP) expression in the FGF-18-containing chitin-PLGA/CaSO 4 gel when compared to cells alone. Further, it was confirmed by studying the expression of osteogenic genes [RUNX2, ALP, BMP-2, osteocalcin (OCN), and osteopontin (OPN)], immunofluorescence staining of BMP-2, OCN, and OPN, and alizarin red S staining. Incorporation of FGF-18 in the hydrogel increased the endothelial cell migration. Further, the regeneration potential of the prepared hydrogels was tested in vivo, and longitudinal live animal μ-CT was performed. FGF-18-loaded chitin-PLGA/CaSO 4 showed early and almost complete bone healing in comparison with chitin-PLGA/CaSO 4 , chitin-PLGA/FGF-18, chitin-PLGA, and sham control systems, as confirmed by hematoxylin and eosin and osteoid tetrachrome stainings

Characterization of human adipose tissue-derived stem cells in vitro culture and in vivo differentiation in a temperature-sensitive chitosan/β- glycerophosphate/collagen hybrid hydrogel

Energy Technology Data Exchange (ETDEWEB)

Song, Kedong, E-mail: Kedongsong@dlut.edu.cn [State Key Laboratory of Fine Chemicals, Dalian R& D Center for Stem Cell and Tissue Engineering, Dalian University of Technology, Dalian 116024 (China); Li, Liying; Yan, Xinyu; Zhang, Wen; Zhang, Yu [State Key Laboratory of Fine Chemicals, Dalian R& D Center for Stem Cell and Tissue Engineering, Dalian University of Technology, Dalian 116024 (China); Wang, Yiwei [Burns Research Group, ANZAC Research Institute, University of Sydney, Concord, NSW, 2139 (Australia); Liu, Tianqing, E-mail: liutq@dlut.edu.cn [State Key Laboratory of Fine Chemicals, Dalian R& D Center for Stem Cell and Tissue Engineering, Dalian University of Technology, Dalian 116024 (China)

2017-01-01

In this study, the interaction of human adipose tissue-derived stem cells (ADSCs) with chitosan/β-glycerophosphate/collagen (C/GP/Co) hybrid hydrogel was test, followed by investigating the capability of engineered adipose tissue formation using this ADSCs seeded hydrogel. The ADSCs were harvested and mixed with a C/GP/Co hydrogel followed by a gelation at 37 °C and an in vitro culture. The results showed that the ADSCs within C/GP/Co hydrogels achieved a 30% of expansion over 7 days in culture medium and encapsulated cell in C/GP/Co hydrogel demonstrated a characteristic morphology with high viability over 5 days. C/GP/Co hydrogel were subcutaneous injected into SD-rats to assess the biocompatibility. The induced ADSCs-C/GP/Co hydrogel and non-induced ADSCs-C/GP/Co hydrogel were subcutaneously injected into nude mice for detecting potential of adipogenic differentiation. It has shown that C/GP/Co hydrogel were well tolerated in SD rats where they had persisted over 4 weeks post implantation. Histology analysis indicated that induced ADSCs-C/GP/Co hydrogel has a greater number of adipocytes and vascularized adipose tissues compared with non-induced ADSCs-C/GP/Co hydrogel. - Highlights: • The hydrogel scaffold was produced using chitosan, β-glycerophosphate and collagen. • This novel hydrogel is in liquid phase at low temperature and is gelatinized at 37 °C. • The new hydrogel provides ADSCs a favorable 3D environment with highly maintenance of proliferation and cytoactive. • ADSCs seeded hydrogel differentiated into adipose tissue, indicating favorable ability of adipogenesis. • This attractive property of C/GP/CO hydrogel points to its value as an excellent scaffold for tissue engineering.

Targeted Drug Delivery in the Suprachoroidal Space by Swollen Hydrogel Pushing

Science.gov (United States)

Jung, Jae Hwan; Desit, Patcharin; Prausnitz, Mark R.

2018-01-01

Purpose The purpose is to target model drug particles to the posterior region of the suprachoroidal space (SCS) of the eye controlled via pushing by hydrogel swelling. Methods A particle formulation containing 1% hyaluronic acid (HA) with fluorescent polymer particles and a hydrogel formulation containing 4% HA were introduced in a single syringe as two layers without mixing, and injected sequentially into the SCS of the rabbit eye ex vivo and in vivo using a microneedle. Distribution of particles in the eye was determined by microscopy. Results During injection, the particle formulation was pushed toward the middle of the SCS by the viscous hydrogel formulation, but less than 12% of particles reached the posterior SCS. After injection, the particle formulation was pushed further toward the macula and optic nerve in the posterior SCS by hydrogel swelling and spreading. Heating the eye to 37°C, or injecting in vivo decreased viscosity and mechanical strength of the hydrogel, thereby allowing it to swell and flow further in the SCS. A high salt concentration (9% NaCl) in the hydrogel formulation further increased hydrogel swelling due to osmotic flow into the hydrogel. In this way, up to 76% of particles were delivered to the posterior SCS from an injection made near the limbus. Conclusions This study shows that model drug particles can be targeted to the posterior SCS by HA hydrogel swelling and pushing without particle functionalization or administering external driving forces. PMID:29677369

Targeted Drug Delivery in the Suprachoroidal Space by Swollen Hydrogel Pushing.

Science.gov (United States)

Jung, Jae Hwan; Desit, Patcharin; Prausnitz, Mark R

2018-04-01

The purpose is to target model drug particles to the posterior region of the suprachoroidal space (SCS) of the eye controlled via pushing by hydrogel swelling. A particle formulation containing 1% hyaluronic acid (HA) with fluorescent polymer particles and a hydrogel formulation containing 4% HA were introduced in a single syringe as two layers without mixing, and injected sequentially into the SCS of the rabbit eye ex vivo and in vivo using a microneedle. Distribution of particles in the eye was determined by microscopy. During injection, the particle formulation was pushed toward the middle of the SCS by the viscous hydrogel formulation, but less than 12% of particles reached the posterior SCS. After injection, the particle formulation was pushed further toward the macula and optic nerve in the posterior SCS by hydrogel swelling and spreading. Heating the eye to 37°C, or injecting in vivo decreased viscosity and mechanical strength of the hydrogel, thereby allowing it to swell and flow further in the SCS. A high salt concentration (9% NaCl) in the hydrogel formulation further increased hydrogel swelling due to osmotic flow into the hydrogel. In this way, up to 76% of particles were delivered to the posterior SCS from an injection made near the limbus. This study shows that model drug particles can be targeted to the posterior SCS by HA hydrogel swelling and pushing without particle functionalization or administering external driving forces.

Viscous hydrophilic injection matrices for serial crystallography

Directory of Open Access Journals (Sweden)

Gabriela Kovácsová

2017-07-01

Full Text Available Serial (femtosecond crystallography at synchrotron and X-ray free-electron laser (XFEL sources distributes the absorbed radiation dose over all crystals used for data collection and therefore allows measurement of radiation damage prone systems, including the use of microcrystals for room-temperature measurements. Serial crystallography relies on fast and efficient exchange of crystals upon X-ray exposure, which can be achieved using a variety of methods, including various injection techniques. The latter vary significantly in their flow rates – gas dynamic virtual nozzle based injectors provide very thin fast-flowing jets, whereas high-viscosity extrusion injectors produce much thicker streams with flow rates two to three orders of magnitude lower. High-viscosity extrusion results in much lower sample consumption, as its sample delivery speed is commensurate both with typical XFEL repetition rates and with data acquisition rates at synchrotron sources. An obvious viscous injection medium is lipidic cubic phase (LCP as it is used for in meso membrane protein crystallization. However, LCP has limited compatibility with many crystallization conditions. While a few other viscous media have been described in the literature, there is an ongoing need to identify additional injection media for crystal embedding. Critical attributes are reliable injection properties and a broad chemical compatibility to accommodate samples as heterogeneous and sensitive as protein crystals. Here, the use of two novel hydrogels as viscous injection matrices is described, namely sodium carboxymethyl cellulose and the thermo-reversible block polymer Pluronic F-127. Both are compatible with various crystallization conditions and yield acceptable X-ray background. The stability and velocity of the extruded stream were also analysed and the dependence of the stream velocity on the flow rate was measured. In contrast with previously characterized injection media, both new

Development of microbial resistant Carbopol nanocomposite hydrogels via a green process

CSIR Research Space (South Africa)

Varaprasad, K

2014-01-01

Full Text Available transform infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and transmission electron microscopy (TEM). The pure and inorganic nanocomposite hydrogels developed were tested...

A new injectable biphasic hydrogel based on partially hydrolyzed polyacrylamide and nano hydroxyapatite, crosslinked with chromium acetate, as scaffold for cartilage regeneration

Science.gov (United States)

Koushki, N.; Tavassoli, H.; Katbab, A. A.; Katbab, P.; Bonakdar, S.

2015-05-01

Polymer scaffolds are applied in the field of tissue engineering as three dimensional structures to organize cells and present stimuli to direct generation of a desired damaged tissue. In situ gelling scaffolds have attracted great attentions, as they are structurally similar to the extra cellular matrix (ECM). In the present work, attempts have been made to design and fabricate a new injectable and crosslinkable biphasic hydrogel based on partially hydrolyzed polyacrylamide (HPAM), chromium acetate as crosslink agent and nanocrystalline hydroxyapatite (nHAp) as reinforcing and bioactive agent for repair and regeneration of damaged cartilage. The distinct characteristic of HPAM is the presence of carboxylate anion groups on its backbone which allows to engineer the structure of the hydrogel for the desired bioactivity with appropriate cells differentiation towards both soft and hard (bone) tissues. The synthesized hydrogel exhibited bifunctional behavior which was derived by its biphasic structure in which one phase was loaded with nano hydroxyapatite to provide integration capability by subchondral bones and fix the hydrogel at cartilage defect without a need for suturing. The other phase differentiates the rabbit adipogenic mesenchymal stem cells (MSCs) towards soft tissue. Rheomechanical spectrometry (RMS) was employed to study the kinetic of the gelation including induction time and rate, as well as to measure the ultimate elastic modulus of the optimum crosslinked hydrogel. Surface tension measurement was also performed to tailor the surface characteristics of the gels. In vitro culturing of the cells inside the crosslinked hydrogel revealed high viability and high differentiation of the encapsulated rabbit stem cells, providing that the chromium acetate level was kept below 0.2 wt%. Based on the obtained results, the designed and fabricated biphasic hydrogel exhibited high potential as carrier for the stem cells for cartilage tissue engineering application

[Thromboresistance of glucose-containing hydrogels].

Science.gov (United States)

Valuev, I L; Valuev, L I; Vanchugova, L V; Obydennova, I V; Valueva, T A

2013-01-01

The thromboresistance of glucose-sensitive polymer hydrogels, modeling one of the functions of the pancreas, namely, the ability to secrete insulin in response to the introduction of glucose into the environment, has been studied. Hydrogels were synthesized by the copolymerization of hydroxyethyl methacrylate with N-acryloyl glucosamine in the presence of a cross-linking agent and subsequently treated with concanavalin A. Introduction of glucose residues into the hydrogel did not result in significant changes in either the number of trombocytes adhered to the hydrogel or the degree of denaturation of blood plasma proteins interacting with the hydrogel. Consequently, the biological activity of insulin did not change after release from the hydrogel. The use of glucose-sensitive hydrogels is supposed to contribute to the development of a novel strategy for the treatment of diabetes.

Bioengineering vascularized tissue constructs using an injectable cell-laden enzymatically crosslinked collagen hydrogel derived from dermal extracellular matrix.

Science.gov (United States)

Kuo, Kuan-Chih; Lin, Ruei-Zeng; Tien, Han-Wen; Wu, Pei-Yun; Li, Yen-Cheng; Melero-Martin, Juan M; Chen, Ying-Chieh

2015-11-01

Tissue engineering promises to restore or replace diseased or damaged tissue by creating functional and transplantable artificial tissues. The development of artificial tissues with large dimensions that exceed the diffusion limitation will require nutrients and oxygen to be delivered via perfusion instead of diffusion alone over a short time period. One approach to perfusion is to vascularize engineered tissues, creating a de novo three-dimensional (3D) microvascular network within the tissue construct. This significantly shortens the time of in vivo anastomosis, perfusion and graft integration with the host. In this study, we aimed to develop injectable allogeneic collagen-phenolic hydroxyl (collagen-Ph) hydrogels that are capable of controlling a wide range of physicochemical properties, including stiffness, water absorption and degradability. We tested whether collagen-Ph hydrogels could support the formation of vascularized engineered tissue graft by human blood-derived endothelial colony-forming cells (ECFCs) and bone marrow-derived mesenchymal stem cells (MSC) in vivo. First, we studied the growth of adherent ECFCs and MSCs on or in the hydrogels. To examine the potential formation of functional vascular networks in vivo, a liquid pre-polymer solution of collagen-Ph containing human ECFCs and MSCs, horseradish peroxidase and hydrogen peroxide was injected into the subcutaneous space or abdominal muscle defect of an immunodeficient mouse before gelation, to form a 3D cell-laden polymerized construct. These results showed that extensive human ECFC-lined vascular networks can be generated within 7 days, the engineered vascular density inside collagen-Ph hydrogel constructs can be manipulated through refinable mechanical properties and proteolytic degradability, and these networks can form functional anastomoses with the existing vasculature to further support the survival of host muscle tissues. Finally, optimized conditions of the cell-laden collagen

Thermo-sensitive liposomes loaded with doxorubicin and lysine modified single-walled carbon nanotubes as tumor-targeting drug delivery system.

Science.gov (United States)

Zhu, Xiali; Xie, Yingxia; Zhang, Yingjie; Huang, Heqing; Huang, Shengnan; Hou, Lin; Zhang, Huijuan; Li, Zhi; Shi, Jinjin; Zhang, Zhenzhong

2014-11-01

This report focuses on the thermo-sensitive liposomes loaded with doxorubicin and lysine-modified single-walled carbon nanotube drug delivery system, which was designed to enhance the anti-tumor effect and reduce the side effects of doxorubicin. Doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes was prepared by reverse-phase evaporation method, the mean particle size was 232.0 ± 5.6 nm, and drug entrapment efficiency was 86.5 ± 3.7%. The drug release test showed that doxorubicin released more quickly at 42℃ than at 37℃. Compared with free doxorubicin, doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes could efficiently cross the cell membranes and afford higher anti-tumor efficacy on the human hepatic carcinoma cell line (SMMC-7721) cells in vitro. For in vivo experiments, the relative tumor volumes of the sarcomaia 180-bearing mice in thermo-sensitive liposomes group and doxorubicin group were significantly smaller than those of N.S. group. Meanwhile, the combination of near-infrared laser irradiation at 808 nm significantly enhanced the tumor growth inhibition both on SMMC-7721 cells and the sarcomaia 180-bearing mice. The quality of life such as body weight, mental state, food and water intake of sarcomaia 180 tumor-bearing mice treated with doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes were much higher than those treated with doxorubicin. In conclusion, doxorubicin-lysine/single-walled carbon nanotube-thermo-sensitive liposomes combined with near-infrared laser irradiation at 808 nm may potentially provide viable clinical strategies for targeting delivery of anti-cancer drugs. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Dual Cross-Linked Biofunctional and Self-Healing Networks to Generate User-Defined Modular Gradient Hydrogel Constructs.

Science.gov (United States)

Wei, Zhao; Lewis, Daniel M; Xu, Yu; Gerecht, Sharon

2017-08-01

Gradient hydrogels have been developed to mimic the spatiotemporal differences of multiple gradient cues in tissues. Current approaches used to generate such hydrogels are restricted to a single gradient shape and distribution. Here, a hydrogel is designed that includes two chemical cross-linking networks, biofunctional, and self-healing networks, enabling the customizable formation of modular gradient hydrogel construct with various gradient distributions and flexible shapes. The biofunctional networks are formed via Michael addition between the acrylates of oxidized acrylated hyaluronic acid (OAHA) and the dithiol of matrix metalloproteinase (MMP)-sensitive cross-linker and RGD peptides. The self-healing networks are formed via dynamic Schiff base reaction between N-carboxyethyl chitosan (CEC) and OAHA, which drives the modular gradient units to self-heal into an integral modular gradient hydrogel. The CEC-OAHA-MMP hydrogel exhibits excellent flowability at 37 °C under shear stress, enabling its injection to generate gradient distributions and shapes. Furthermore, encapsulated sarcoma cells respond to the gradient cues of RGD peptides and MMP-sensitive cross-linkers in the hydrogel. With these superior properties, the dual cross-linked CEC-OAHA-MMP hydrogel holds significant potential for generating customizable gradient hydrogel constructs, to study and guide cellular responses to their microenvironment such as in tumor mimicking, tissue engineering, and stem cell differentiation and morphogenesis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design of a Versatile pH-Responsive Hydrogel for Potential Oral Delivery of Gastric-Sensitive Bioactives

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Angus R. Hibbins

2017-09-01

Full Text Available A pH-responsive hydrogel system was prepared by free radical polymerization of acrylamide and methyl acrylic acid in the presence of N-N′-methylene bisacrylamide. Sodium bicarbonate was further applied as a blowing agent, which afforded a porous hydrogel structure. The hydrogel system achieved a constant super swelling rate within simulated intestinal buffer (~4%/min and remained relatively static within simulated gastric buffer (~0.8%/min. The hydrogel system was able to achieve matrix resilience greater than 30% under a relatively high strain of 40%. In addition, the hydrogel system demonstrated significant swelling properties in response to simulated intestinal environmental over 24 h, with contrasting characteristics in simulated gastric buffer. The hydrogel demonstrated type IV isotherm porosity characteristics, with remarkable MRI and SEM variations in gastric and intestinal simulated fluids. Drug loading was observed to be greater than 98% using theophylline as a prototype drug, evaluating its controlled release kinetics over 24 h. The hydrogel exhibited substantial pH-responsive activity, which could be used as a versatile platform for targeted release of gastric-sensitive therapeutics to the small intestine.

Kinetic Degradation and Controlled Drug Delivery System Studies for Sensitive Hydrogels Prepared by Gamma Irradiation

International Nuclear Information System (INIS)

Eid, M.; El-Arnaouty, M.B.

2008-01-01

Ternary mixtures of N-vinyle-2-pyrrolidone(NVP ), itaconic acid (IA) and gelatin (G) were gamma irradiated to prepared poly(NVP/IA/G) hydrogels. The equilibrium kinetic swelling, drug release behavior, Scan Electron Microscope (SEM) and the swelling-degradation kinetics were studied. Both the diffusion exponent and the diffusion coefficient increase with increasing content of (IA). Also, the swelling behavior of copolymer hydrogels in response to ph value of the external media was studied, it is noted that the highest swelling values at ph 4. The in vitro drug release behavior of these hydrogels was examined by quantification analysis with a UV/VIS spectrophotometers. Chlorpromazine hydrochloride was loaded into dried hydrogels to investigate the stimuli-sensitive property at the specific ph. The release studies show that the highest value of release was at ph 4 which can be used for drug delivery system

Design, Optimization, and Evaluation of a Novel Metronidazole-Loaded Gastro-Retentive pH-Sensitive Hydrogel.

Science.gov (United States)

El-Mahrouk, Galal M; Aboul-Einien, Mona H; Makhlouf, Amal I

2016-12-01

Floating pH-sensitive chitosan hydrogels containing metronidazole were developed for the eradication of Helicobacter pylori from the stomach. Hydrogels were prepared by crosslinking medium or high molecular weight chitosan in lyophilized solutions containing metronidazole using either citrate or tripolyphosphate (TPP) salts at 1% or 2% concentration. A 2 3 factorial design was developed to study the influence of formulation parameters on the physical characteristics of the prepared hydrogels. The interaction between hydrogel components was investigated. The morphology of the prepared hydrogels was inspected and their percentage swelling, release pattern, and moisture content were evaluated. The results revealed the absence of interaction between hydrogel components and their highly porous structure. Percentage swelling of the hydrogels was much higher, and drug release was faster in gastric pH compared with intestinal pH. The formula prepared using 2% high molecular weight chitosan and 2% TPP significantly swelled (700%) within the first 4 h and released the loaded drug over a period of 24 h. Its moisture content was not affected by storage at high relative humidity. Therefore, this formula was selected to be tested in dogs for its gastric retention (using X-ray radiography) and efficacy in the eradication of H. pylori (using histopathological and microbiological examination). The results revealed that the prepared hydrogel formula was retained in dog stomach for at least 48 h, and it was more effective against H. pylori than the commercially available oral metronidazole tablets (Flagyl®).

Structure- Property Behavior of Poly (acrylic acid) Hydrogels Synthesized by Radiation Induced Polymerization

International Nuclear Information System (INIS)

Nizam El-Din, H.M.M.; Ibrahim, M.S.

2000-01-01

Hydrogel containing hydroxyl group based on glycerol, ethylene glycol and acrylic monomer, have been prepared by using gamma radiation. The application of the prepared hydrogel for recovery of CU 2+ , Co 2+ , Ni 2+ , and Pb 2+ was also studied. The hydrogel for complexes with metals have been isolated and characterized by using different spectroscopic techniques IR and thermal analysis. TGA thermo grams were used to determine the kinetic parameters such as activation energy and order of reaction. The complexometric titration showed that the hydrogels have a great affinity to recover the metal ions in the following order Pb 2+ > Ni 2+ > Cu 2+ > Co 2+ . However the hydrogel containing glycerol has a great tendency towards metals recovery than than the one containing ethylene glycol

Synthesis and Characterization of Injectable Hydrogels with Varying Collagen–Chitosan–Thymosin β4 Composition for Myocardial Infarction Therapy

Directory of Open Access Journals (Sweden)

Achmad Dzihan Shaghiera

2018-04-01

Full Text Available Thirty percent of global mortalities are caused by cardiovascular disease, and 54% of the aforementioned amount is instigated by ischemic heart disease that triggered myocardial infarction. Myocardial infarction is due to blood flow cessation in certain coronary arteries that causes lack of oxygen (ischemia and stimulates myocardial necrosis. One of the methods to treat myocardial infarction consists in injecting cells or active biomolecules and biomaterials into heart infarction locations. This study aimed to investigate the characteristics of a collagen–chitosan-based hydrogel with variations in its chitosan composition. The prepared hydrogels contained thymosin β4 (Tβ4, a 43-amino acid peptide with angiogenic and cardioprotective properties which can act as a bioactive molecule for the treatment of myocardial infarction. A morphological structure analysis showed that the hydrogels lacked interconnecting pores. All samples were not toxic on the basis of a cytotoxicity test. A histopathological anatomy test showed that the collagen–chitosan–thymosin β4 hydrogels could stimulate angiogenesis and epicardial heart cell migration, as demonstrated by the evaluation of the number of blood vessels and the infiltration extent of myofibroblasts.

A hydrogel biosensor for high selective and sensitive detection of amyloid-beta oligomers.

Science.gov (United States)

Sun, Liping; Zhong, Yong; Gui, Jie; Wang, Xianwu; Zhuang, Xiaorong; Weng, Jian

2018-01-01

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive and memory impairment. It is the most common neurological disease that causes dementia. Soluble amyloid-beta oligomers (AβO) in blood or cerebrospinal fluid (CSF) are the pathogenic biomarker correlated with AD. A simple electrochemical biosensor using graphene oxide/gold nanoparticles (GNPs) hydrogel electrode was developed in this study. Thiolated cellular prion protein (PrP C ) peptide probe was immobilized on GNPs of the hydrogel electrode to construct an AβO biosensor. Electrochemical impedance spectroscopy was utilized for AβO analysis. The specific binding between AβO and PrP C probes on the hydrogel electrode resulted in an increase in the electron-transfer resistance. The biosensor showed high specificity and sensitivity for AβO detection. It could selectively differentiate AβO from amyloid-beta (Aβ) monomers or fibrils. Meanwhile, it was highly sensitive to detect as low as 0.1 pM AβO in artificial CSF or blood plasma. The linear range for AβO detection is from 0.1 pM to 10 nM. This biosensor could be used as a cost-effective tool for early diagnosis of AD due to its high electrochemical performance and bionic structure.

Enhanced Mechanical Properties in Cellulose Nanocrystal-Poly(oligoethylene glycol methacrylate) Injectable Nanocomposite Hydrogels through Control of Physical and Chemical Cross-Linking.

Science.gov (United States)

De France, Kevin J; Chan, Katelyn J W; Cranston, Emily D; Hoare, Todd

2016-02-08

While injectable hydrogels have several advantages in the context of biomedical use, their generally weak mechanical properties often limit their applications. Herein, we describe in situ-gelling nanocomposite hydrogels based on poly(oligoethylene glycol methacrylate) (POEGMA) and rigid rod-like cellulose nanocrystals (CNCs) that can overcome this challenge. By physically incorporating CNCs into hydrazone cross-linked POEGMA hydrogels, macroscopic properties including gelation rate, swelling kinetics, mechanical properties, and hydrogel stability can be readily tailored. Strong adsorption of aldehyde- and hydrazide-modified POEGMA precursor polymers onto the surface of CNCs promotes uniform dispersion of CNCs within the hydrogel, imparts physical cross-links throughout the network, and significantly improves mechanical strength overall, as demonstrated by quartz crystal microbalance gravimetry and rheometry. When POEGMA hydrogels containing mixtures of long and short ethylene oxide side chain precursor polymers were prepared, transmission electron microscopy reveals that phase segregation occurs with CNCs hypothesized to preferentially locate within the stronger adsorbing short side chain polymer domains. Incorporating as little as 5 wt % CNCs results in dramatic enhancements in mechanical properties (up to 35-fold increases in storage modulus) coupled with faster gelation rates, decreased swelling ratios, and increased stability versus hydrolysis. Furthermore, cell viability can be maintained within 3D culture using these hydrogels independent of the CNC content. These properties collectively make POEGMA-CNC nanocomposite hydrogels of potential interest for various biomedical applications including tissue engineering scaffolds for stiffer tissues or platforms for cell growth.

A highly sensitive, low-cost, wearable pressure sensor based on conductive hydrogel spheres

KAUST Repository

Tai, Yanlong

2015-01-01

Wearable pressure sensing solutions have promising future for practical applications in health monitoring and human/machine interfaces. Here, a highly sensitive, low-cost, wearable pressure sensor based on conductive single-walled carbon nanotube (SWCNT)/alginate hydrogel spheres is reported. Conductive and piezoresistive spheres are embedded between conductive electrodes (indium tin oxide-coated polyethylene terephthalate films) and subjected to environmental pressure. The detection mechanism is based on the piezoresistivity of the SWCNT/alginate conductive spheres and on the sphere-electrode contact. Step-by-step, we optimized the design parameters to maximize the sensitivity of the sensor. The optimized hydrogel sensor exhibited a satisfactory sensitivity (0.176 ΔR/R0/kPa-1) and a low detectable limit (10 Pa). Moreover, a brief response time (a few milliseconds) and successful repeatability were also demonstrated. Finally, the efficiency of this strategy was verified through a series of practical tests such as monitoring human wrist pulse, detecting throat muscle motion or identifying the location and the distribution of an external pressure using an array sensor (4 × 4). © 2015 The Royal Society of Chemistry.

Dual responsive supramolecular hydrogel with electrochemical activity.

Science.gov (United States)

Du, Ping; Liu, Jianghua; Chen, Guosong; Jiang, Ming

2011-08-02

Supramolecular materials with reversible responsiveness to environmental changes are of particular research interest in recent years. Inclusion complexation between cyclodextrin (CD) and ferrocene (Fc) is well-known and extensively studied because of its reversible association-dissociation controlled by the redox state of Fc. Although there are quite a few reported nanoscale materials incorporating this host-guest pair, polymeric hydrogels with electrochemical activity based on this interactive pair are still rare. Taking advantage of our previous reported hybrid inclusion complex (HIC) hydrogel structure, a new Fc-HIC was designed and obtained with β-CD-modified quantum dots as the core and Fc-ended diblock co-polymer p(DMA-b-NIPAM) as the shell, to achieve an electrochemically active hydrogel at elevated temperatures. Considering the two independent cross-linking strategies in the network structure, i.e., the interchain aggregation of pNIPAM and inclusion complexation between CD and Fc on the surface of the quantum dots, the hydrogel was fully thermo-reversible and its gel-sol transition was achieved after the addition of either an oxidizing agent or a competitive guest to Fc.

Oxide nanomembrane hybrids with enhanced mechano- and thermo-sensitivity for semitransparent epidermal electronics.

Science.gov (United States)

Park, Minjoon; Do, Kyungsik; Kim, Jaemin; Son, Donghee; Koo, Ja Hoon; Park, Jinkyung; Song, Jun-Kyul; Kim, Ji Hoon; Lee, Minbaek; Hyeon, Taeghwan; Kim, Dae-Hyeong

2015-05-01

Oxide nanomembrane hybrids with enhanced mechano- and thermo-sensitivity for semitransparent epidermal electronics are developed. The use of nanomaterials (single wall nanotubes and silver nanoparticles) embedded in the oxide nanomembranes significantly enhances mechanical and thermal sensitivities. These mechanical and thermal sensors are utilized in wheelchair control and hypothermia detection, which are useful for patients with strokes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation, properties and biological application of pH-sensitive poly(ethylene oxide) (PEO) hydrogels grafted with acrylic acid(AAc) using gamma-ray irradiation

International Nuclear Information System (INIS)

Nho, Y.C.; Mook Lim, Youn; Moo Lee, Young

2004-01-01

pH-sensitive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing it in the small intestine. In this study, hydrogels based on poly(ethylene oxide) (PEO) networks grafted with acrylic acid (AAc) were prepared via a two-step process. PEO hydrogels were prepared by γ-ray irradiation, and then grafting by AAc monomer onto the PEO hydrogels with the subsequent irradiation (radiation dose: 5-20 kGy, dose rate: 2.15 kGy/h). These grafted hydrogels showed a pH-sensitive swelling behavior. The grafted hydrogels were used as a carrier for the drug delivery systems for the controlled release of insulin. The in vitro drug release behaviors of these hydrogels were examined by quantification analysis with a UV/VIS spectrophotometer. Insulin was loaded into freeze-dried hydrogels (7 mmx3 mmx2.5 mm) and administrated orally to healthy and diabetic Wistar rats. The oral administration of insulin-loaded hydrogels to Wistar rats decreased the blood glucose levels obviously for at least 4 h due to the absorption of insulin in the gastrointestinal tract

A Case of Special Complication following a Large Amount of Polyacrylamide Hydrogel Injected into the Epicranial Aponeurosis: Leukocytopenia

Directory of Open Access Journals (Sweden)

Li Rong

2015-01-01

Full Text Available Polyacrylamide hydrogel (PAAG has been used as an injectable filler for soft tissue augmentation of different body parts, such as the face, breasts, and penis. However, this is the first report of leukocytopenia after injection of a large amount of PAAG in the epicranial aponeurosis. After receiving PAAG injection for craniofacial contouring, the female patient described herein experienced recurrent swelling, temporal pain (particularly with changes in ambient temperature and facial expression, and ultimately leukocytopenia due to widespread migration of the injected PAAG. We removed most of the PAAG from the affected tissues and the leukocytopenia disappeared 1 year after the operation. Based on this case, we hypothesize that injection of a large amount of PAAG into tissues that have ample blood supply, such as the epicranial aponeurosis, may induce leukocytopenia.

Therapeutic application of injectable thermosensitive hydrogel in preventing local breast cancer recurrence and improving incision wound healing in a mouse model

Science.gov (United States)

Lei, Na; Gong, Changyang; Qian, Zhiyong; Luo, Feng; Wang, Cheng; Wang, Helan; Wei, Yuquan

2012-08-01

Many drug delivery systems (DDSs) have been investigated for local targeting of malignant disease with the intention of increasing anti-tumor activity and minimizing systemic toxicity. An injectable thermosensitive hydrogel was applied to prevent locoregional recurrence of 4T1 breast cancer in a mouse model. The presented hydrogel, which is based on poly(ethyleneglycol)-poly(ε-caprolactone)-poly(ethylene glycol) (PEG-PCL-PEG, PECE), flows freely at normal temperature, forms a gel within seconds in situ at body temperature, and eventually releases the drug in a consistent and sustained fashion as it gradually biodegrades. Locoregional recurrence after primary tumor removal was significantly inhibited in mice treated with the paclitaxel (PTX)-loaded PECE hydrogel subcutaneously (9.1%) administered, compared with the blank hydrogel (80.0%), systemic (77.8%) and locally (75.0%) administered PTX, and the control group (100%) (P 0.05), in agreement with histopathological examinations. This novel DDSs represents a promising approach for local adjuvant therapy in malignant disease.

Skin-Inspired Multifunctional Autonomic-Intrinsic Conductive Self-Healing Hydrogels with Pressure Sensitivity, Stretchability, and 3D Printability.

Science.gov (United States)

Darabi, Mohammad Ali; Khosrozadeh, Ali; Mbeleck, Rene; Liu, Yuqing; Chang, Qiang; Jiang, Junzi; Cai, Jun; Wang, Quan; Luo, Gaoxing; Xing, Malcolm

2017-08-01

The advent of conductive self-healing (CSH) hydrogels, a class of novel materials mimicking human skin, may change the trajectory of the industrial process because of their potential applications in soft robots, biomimetic prostheses, and health-monitoring systems. Here, the development of a mechanically and electrically self-healing hydrogel based on physically and chemically cross-linked networks is reported. The autonomous intrinsic self-healing of the hydrogel is attained through dynamic ionic interactions between carboxylic groups of poly(acrylic acid) and ferric ions. A covalent cross-linking is used to support the mechanical structure of the hydrogel. Establishing a fair balance between the chemical and physical cross-linking networks together with the conductive nanostructure of polypyrrole networks leads to a double network hydrogel with bulk conductivity, mechanical and electrical self-healing properties (100% mechanical recovery in 2 min), ultrastretchability (1500%), and pressure sensitivity. The practical potential of CSH hydrogels is further revealed by their application in human motion detection and their 3D-printing performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Alginate nanobeads interspersed fibrin network as in situ forming hydrogel for soft tissue engineering.

Science.gov (United States)

Deepthi, S; Jayakumar, R

2018-06-01

Hydrogels are a class of materials that has the property of injectability and in situ gel formation. This property of hydrogels is manipulated in this study to develop a biomimetic bioresorbable injectable system of alginate nanobeads interspersed in fibrin network. Alginate nanobeads developed by calcium cross-linking yielded a size of 200-500 nm. The alginate nanobeads fibrin hydrogel was formed using dual syringe apparatus. Characterization of the in situ injectable hydrogel was done by SEM, FTIR and Rheometer. The developed hydrogel showed mechanical strength of 19 kPa which provides the suitable compliance for soft tissue engineering. Cytocompatibility studies using human umbilical cord blood derived mesenchymal stem cells showed good attachment, proliferation and infiltration within the hydrogel similar to fibrin gel. The developed in situ forming hydrogel could be a suitable delivery carrier of stem cells for soft tissue regeneration.

Dual-functional transdermal drug delivery system with controllable drug loading based on thermosensitive poloxamer hydrogel for atopic dermatitis treatment

Science.gov (United States)

Wang, Wenyi; Wat, Elaine; Hui, Patrick C. L.; Chan, Ben; Ng, Frency S. F.; Kan, Chi-Wai; Wang, Xiaowen; Hu, Huawen; Wong, Eric C. W.; Lau, Clara B. S.; Leung, Ping-Chung

2016-04-01

The treatment of atopic dermatitis (AD) has long been viewed as a problematic issue by the medical profession. Although a wide variety of complementary therapies have been introduced, they fail to combine the skin moisturizing and drug supply for AD patients. This study reports the development of a thermo-sensitive Poloxamer 407/Carboxymethyl cellulose sodium (P407/CMCs) composite hydrogel formulation with twin functions of moisture and drug supply for AD treatment. It was found that the presence of CMCs can appreciably improve the physical properties of P407 hydrogel, which makes it more suitable for tailored drug loading. The fabricated P407/CMCs composite hydrogel was also characterized in terms of surface morphology by field emission scanning electron microscopy (FE-SEM), rheological properties by a rheometer, release profile in vitro by dialysis method and cytotoxicity test. More importantly, the findings from transdermal drug delivery behavior revealed that P407/CMCs showed desirable percutaneous performance. Additionally, analysis of cytotoxicity test suggested that P407/CMCs composite hydrogel is a high-security therapy for clinical trials and thus exhibits a promising way to treat AD with skin moisturizing and medication.

Synthesis, Characterization, and Acute Oral Toxicity Evaluation of pH-Sensitive Hydrogel Based on MPEG, Poly(ε-caprolactone, and Itaconic Acid

Directory of Open Access Journals (Sweden)

Liwei Tan

2013-01-01

Full Text Available A kind of chemically cross-linked pH-sensitive hydrogels based on methoxyl poly(ethylene glycol-poly(caprolactone-acryloyl chloride (MPEG-PCL-AC, PECA, poly(ethylene glycol methyl ether methacrylate (MPEGMA, MEG, N,N-methylenebisacrylamide (BIS, and itaconic acid (IA were prepared without using any organic solvent by heat-initiated free radical method. The obtained macromonomers and hydrogels were characterized by 1H NMR and FT-IR, respectively. Morphology study of hydrogels was also investigated in this paper, and it showed that the hydrogels had good pH-sensitivity. The acute toxicity test and histopathological study were conducted in BALB/c mice. The results indicated that the maximum tolerance dose of the hydrogel was higher than 10000 mg/kg body weight. No morality or signs of toxicity were observed during the whole 7-day observation period. Compared to the control groups, there were no important adverse effects in the variables of hematology routine test and serum chemistry analysis both in male or female treatment group. Histopathological study also did not show any significant lesions, including heart, liver, lung, spleen, kidney, stomach, intestine, and testis. All the results demonstrated that this hydrogel was nontoxic after gavage. Thus, the hydrogel might be the biocompatible potential candidate for oral drug delivery system.

Novel thermo-sensitive core-shell nanoparticles for targeted paclitaxel delivery

International Nuclear Information System (INIS)

Li Yuanpei; Pan Shirong; Zhang Wei; Du Zhuo

2009-01-01

Novel thermo-sensitive nanoparticles self-assembled from poly(N,N-diethylacrylamide- co-acrylamide)-block-poly(γ-benzyl L-glutamate) were designed for targeted drug delivery in localized hyperthermia. The lower critical solution temperature (LCST) of nanoparticles was adjusted to a level between physiological body temperature (37 deg. C) and that used in local hyperthermia (about 43 deg. C). The temperature-dependent performances of the core-shell nanoparticles were systemically studied by nuclear magnetic resonance (NMR), circular dichroism (CD), fluorescence spectroscopy, dynamic light scattering (DLS), and atom force microscopy (AFM). The mean diameter of the nanoparticles increased slightly from 110 to 129 nm when paclitaxel (PTX), a poorly water-soluble anti-tumor drug, was encapsulated. A stability study in bovine serum albumin (BSA) solution indicated that the PTX loaded nanoparticles may have a long circulation time under physiological environments as the LCST was above physiological body temperature and the shell remained hydrophilic at 37 deg.C. The PTX release profiles showed thermo-sensitive controlled behavior. The proliferation inhibiting activity of PTX loaded nanoparticles was evaluated against Hela cells in vitro, compared with Taxol (a formulation of paclitaxel dissolved in Cremophor EL and ethanol). The cytotoxicity of PTX loaded nanoparticles increased obviously when hyperthermia was performed. The nanoparticles synthesized here could be an ideal candidate for thermal triggered anti-tumor PTX delivery system.

Alginate nanobeads interspersed fibrin network as in situ forming hydrogel for soft tissue engineering

Directory of Open Access Journals (Sweden)

S. Deepthi

2018-06-01

Full Text Available Hydrogels are a class of materials that has the property of injectability and in situ gel formation. This property of hydrogels is manipulated in this study to develop a biomimetic bioresorbable injectable system of alginate nanobeads interspersed in fibrin network. Alginate nanobeads developed by calcium cross-linking yielded a size of 200–500 nm. The alginate nanobeads fibrin hydrogel was formed using dual syringe apparatus. Characterization of the in situ injectable hydrogel was done by SEM, FTIR and Rheometer. The developed hydrogel showed mechanical strength of 19 kPa which provides the suitable compliance for soft tissue engineering. Cytocompatibility studies using human umbilical cord blood derived mesenchymal stem cells showed good attachment, proliferation and infiltration within the hydrogel similar to fibrin gel. The developed in situ forming hydrogel could be a suitable delivery carrier of stem cells for soft tissue regeneration.

Light Responsive Two-Component Supramolecular Hydrogel: A Sensitive Platform for Humidity Sensors

KAUST Repository

Samai, Suman

2016-02-15

The supramolecular assembly of anionic azobenzene dicarboxylate and cationic cetyltrimethylammonium bromide (CTAB) formed a stimuli responsive hydrogel with a critical gelation concentration (CGC) of 0.33 wt%. This self-sustainable two-component system was able to repair damage upon light irradiation. Moreover, it was successfully employed in the fabrication of highly sensitive humidity sensors for the first time.

Light Responsive Two-Component Supramolecular Hydrogel: A Sensitive Platform for Humidity Sensors

KAUST Repository

Samai, Suman; Sapsanis, Christos; Patil, Sachin; Ezzeddine, Alaa; Moosa, Basem; Omran, Hesham; Emwas, Abdul-Hamid M.; Salama, Khaled N.; Khashab, Niveen M.

2016-01-01

The supramolecular assembly of anionic azobenzene dicarboxylate and cationic cetyltrimethylammonium bromide (CTAB) formed a stimuli responsive hydrogel with a critical gelation concentration (CGC) of 0.33 wt%. This self-sustainable two-component system was able to repair damage upon light irradiation. Moreover, it was successfully employed in the fabrication of highly sensitive humidity sensors for the first time.

Thermo-elastic optical coherence tomography.

Science.gov (United States)

Wang, Tianshi; Pfeiffer, Tom; Wu, Min; Wieser, Wolfgang; Amenta, Gaetano; Draxinger, Wolfgang; van der Steen, Antonius F W; Huber, Robert; Soest, Gijs van

2017-09-01

The absorption of nanosecond laser pulses induces rapid thermo-elastic deformation in tissue. A sub-micrometer scale displacement occurs within a few microseconds after the pulse arrival. In this Letter, we investigate the laser-induced thermo-elastic deformation using a 1.5 MHz phase-sensitive optical coherence tomography (OCT) system. A displacement image can be reconstructed, which enables a new modality of phase-sensitive OCT, called thermo-elastic OCT. An analysis of the results shows that the optical absorption is a dominating factor for the displacement. Thermo-elastic OCT is capable of visualizing inclusions that do not appear on the structural OCT image, providing additional tissue type information.

Thermo-sensitively and magnetically ordered mesoporous carbon nanospheres for targeted controlled drug release and hyperthermia application.

Science.gov (United States)

Chen, Lin; Zhang, Huan; Zheng, Jing; Yu, Shiping; Du, Jinglei; Yang, Yongzhen; Liu, Xuguang

2018-03-01

A multifunctional nanoplatform based on thermo-sensitively and magnetically ordered mesoporous carbon nanospheres (TMOMCNs) is developed for effective targeted controlled release of doxorubicin hydrochloride (DOX) and hyperthermia in this work. The morphology, specific surface area, porosity, thermo-stability, thermo-sensitivity, as well as magnetism properties of TMOMCNs were verified by high resolution transmission electron microscopy, field emission scanning electron microscopy, thermo-gravimetric analysis, X-ray diffraction, Brunauer-Emmeltt-Teller surface area analysis, dynamic light scattering and vibrating sample magnetometry measurement. The results indicate that TMOMCNs have an average diameter of ~146nm with a lower critical solution temperature at around 39.5°C. They are superparamagnetic with a magnetization of 10.15emu/g at 20kOe. They generate heat when inductive magnetic field is applied to them and have a normalized specific absorption rate of 30.23W/g at 230kHz and 290Oe, showing good potential for hyperthermia. The DOX loading and release results illustrate that the loading capacity is 135.10mg/g and release performance could be regulated by changing pH and temperature. The good targeting, DOX loading and release and hyperthermia properties of TMOMCNs offer new probabilities for high effectiveness and low toxicity of cancer chemotherapy. Copyright © 2017 Elsevier B.V. All rights reserved.

Injectable skeletal muscle matrix hydrogel promotes neovascularization and muscle cell infiltration in a hindlimb ischemia model

Directory of Open Access Journals (Sweden)

JA DeQuach

2012-06-01

Full Text Available Peripheral artery disease (PAD currently affects approximately 27 million patients in Europe and North America, and if untreated, may progress to the stage of critical limb ischemia (CLI, which has implications for amputation and potential mortality. Unfortunately, few therapies exist for treating the ischemic skeletal muscle in these conditions. Biomaterials have been used to increase cell transplant survival as well as deliver growth factors to treat limb ischemia; however, existing materials do not mimic the native skeletal muscle microenvironment they are intended to treat. Furthermore, no therapies involving biomaterials alone have been examined. The goal of this study was to develop a clinically relevant injectable hydrogel derived from decellularized skeletal muscle extracellular matrix and examine its potential for treating PAD as a stand-alone therapy by studying the material in a rat hindlimb ischemia model. We tested the mitogenic activity of the scaffold’s degradation products using an in vitro assay and measured increased proliferation rates of smooth muscle cells and skeletal myoblasts compared to collagen. In a rat hindlimb ischemia model, the femoral artery was ligated and resected, followed by injection of 150 µL of skeletal muscle matrix or collagen 1 week post-injury. We demonstrate that the skeletal muscle matrix increased arteriole and capillary density, as well as recruited more desmin-positive and MyoD-positive cells compared to collagen. Our results indicate that this tissue-specific injectable hydrogel may be a potential therapy for treating ischemia related to PAD, as well as have potential beneficial effects on restoring muscle mass that is typically lost in CLI.

Novel pH-sensitive photopolymer hydrogel and its holographic sensing response for solution characterization

Science.gov (United States)

Liu, Hongpeng; Yu, Dan; Zhou, Ke; Wang, Shichan; Luo, Suhua; Li, Li; Wang, Weibo; Song, Qinggong

2018-05-01

Optical sensor based on pH-sensitive hydrogel has important practical applications in medical diagnosis and bio-sensor areas. This report details the experimental and theoretical results from a novel photosensitive polymer hydrogel holographic sensor, which formed by thermal polymerization of 2-hydroxyethyl methacrylate, for the detection of pH in buffer. Volume grating recorded in the polymer hydrogel was employed in response to the performance of solution. Methacrylic acid with carboxyl groups was selected as the primary co-monomer to functionalize the matrix. Peak diffraction spectrum of holographic grating determined as a primary sensing parameter was characterized to reflect the change in pH. The extracted linear relation between peak wavelength and pH value provided a probability for the practical application of holographic sensor. To explore the sensing mechanism deeply, a theoretical model was used to describe the relevant holographic processes, including grating formation, dark diffusional enhancement, and final fringe swelling. Numerical result further showed all of the dynamic processes and internal sensing physical mechanism. These experimental and numerical results provided a significant foundation for the development of novel holographic sensor based on polymer hydrogel and improvement of its practical applicability.

Injectable calcium phosphate with hydrogel fibers encapsulating induced pluripotent, dental pulp and bone marrow stem cells for bone repair

Energy Technology Data Exchange (ETDEWEB)

Wang, Lin [VIP Integrated Department, School and Hospital of Stomatology, Jilin University, Changchun, Jilin 130011,China (China); Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Zhang, Chi [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); State Key Laboratory of Oral Diseases, West China School of Stomatology, Sichuan University, Chengdu 610041 (China); Li, Chunyan [VIP Integrated Department, School and Hospital of Stomatology, Jilin University, Changchun, Jilin 130011,China (China); Weir, Michael D. [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Wang, Ping, E-mail: pwang@umaryland.edu [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Reynolds, Mark A. [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Zhao, Liang, E-mail: lzhaonf@126.com [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Department of Orthopaedic Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515 (China); Xu, Hockin H.K. [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201 (United States); Department of Mechanical Engineering, University of Maryland Baltimore County, Baltimore County, MD 21250 (United States)

2016-12-01

Human induced pluripotent stem cell-derived mesenchymal stem cells (hiPSC-MSCs), dental pulp stem cells (hDPSCs) and bone marrow MSCs (hBMSCs) are exciting cell sources in regenerative medicine. However, there has been no report comparing hDPSCs, hBMSCs and hiPSC-MSCs for bone engineering in an injectable calcium phosphate cement (CPC) scaffold. The objectives of this study were to: (1) develop a novel injectable CPC containing hydrogel fibers encapsulating stem cells for bone engineering, and (2) compare cell viability, proliferation and osteogenic differentiation of hDPSCs, hiPSC-MSCs from bone marrow (BM-hiPSC-MSCs) and from foreskin (FS-hiPSC-MSCs), and hBMSCs in CPC for the first time. The results showed that the injection did not harm cell viability. The porosity of injectable CPC was 62%. All four types of cells proliferated and differentiated down the osteogenic lineage inside hydrogel fibers in CPC. hDPSCs, BM-hiPSC-MSCs, and hBMSCs exhibited high alkaline phosphatase, runt-related transcription factor, collagen I, and osteocalcin gene expressions. Cell-synthesized minerals increased with time (p < 0.05), with no significant difference among hDPSCs, BM-hiPSC-MSCs and hBMSCs (p > 0.1). Mineralization by hDPSCs, BM-hiPSC-MSCs, and hBMSCs inside CPC at 14 d was 14-fold that at 1 d. FS-hiPSC-MSCs were inferior in osteogenic differentiation compared to the other cells. In conclusion, hDPSCs, BM-hiPSC-MSCs and hBMSCs are similarly and highly promising for bone tissue engineering; however, FS-hiPSC-MSCs were relatively inferior in osteogenesis. The novel injectable CPC with cell-encapsulating hydrogel fibers may enhance bone regeneration in dental, craniofacial and orthopedic applications. - Highlights: • The osteogenic differentiation of hiPSC-MSCs from different origins, hDPSCs and hBMSCs were first investigated and compared in this study. • hDPSCs and hiPSC-MSCs from bone marrow represented viable alternatives to hBMSCs in bone tissue engineering. • hi

Injectable calcium phosphate with hydrogel fibers encapsulating induced pluripotent, dental pulp and bone marrow stem cells for bone repair

International Nuclear Information System (INIS)

Wang, Lin; Zhang, Chi; Li, Chunyan; Weir, Michael D.; Wang, Ping; Reynolds, Mark A.; Zhao, Liang; Xu, Hockin H.K.

2016-01-01

Human induced pluripotent stem cell-derived mesenchymal stem cells (hiPSC-MSCs), dental pulp stem cells (hDPSCs) and bone marrow MSCs (hBMSCs) are exciting cell sources in regenerative medicine. However, there has been no report comparing hDPSCs, hBMSCs and hiPSC-MSCs for bone engineering in an injectable calcium phosphate cement (CPC) scaffold. The objectives of this study were to: (1) develop a novel injectable CPC containing hydrogel fibers encapsulating stem cells for bone engineering, and (2) compare cell viability, proliferation and osteogenic differentiation of hDPSCs, hiPSC-MSCs from bone marrow (BM-hiPSC-MSCs) and from foreskin (FS-hiPSC-MSCs), and hBMSCs in CPC for the first time. The results showed that the injection did not harm cell viability. The porosity of injectable CPC was 62%. All four types of cells proliferated and differentiated down the osteogenic lineage inside hydrogel fibers in CPC. hDPSCs, BM-hiPSC-MSCs, and hBMSCs exhibited high alkaline phosphatase, runt-related transcription factor, collagen I, and osteocalcin gene expressions. Cell-synthesized minerals increased with time (p < 0.05), with no significant difference among hDPSCs, BM-hiPSC-MSCs and hBMSCs (p > 0.1). Mineralization by hDPSCs, BM-hiPSC-MSCs, and hBMSCs inside CPC at 14 d was 14-fold that at 1 d. FS-hiPSC-MSCs were inferior in osteogenic differentiation compared to the other cells. In conclusion, hDPSCs, BM-hiPSC-MSCs and hBMSCs are similarly and highly promising for bone tissue engineering; however, FS-hiPSC-MSCs were relatively inferior in osteogenesis. The novel injectable CPC with cell-encapsulating hydrogel fibers may enhance bone regeneration in dental, craniofacial and orthopedic applications. - Highlights: • The osteogenic differentiation of hiPSC-MSCs from different origins, hDPSCs and hBMSCs were first investigated and compared in this study. • hDPSCs and hiPSC-MSCs from bone marrow represented viable alternatives to hBMSCs in bone tissue engineering. • hi

Development of biocompatible glycodynameric hydrogels joining two natural motifs by dynamic constitutional chemistry.

Science.gov (United States)

Marin, Luminita; Ailincai, Daniela; Morariu, Simona; Tartau-Mititelu, Liliana

2017-08-15

The paper focusses on the synthesis of novel hydrogels by joining natural biodegradable compounds with the aim to achieve biocompatible materials for bio related applications. The hydrogels were prepared from chitosan and citral by constitutional dynamic chemistry, incorporating both molecular and supramolecular dynamic features. The hydrophobic flexible citral has been reversible immobilized onto the hydrophilic chitosan backbone via imine bonds to form amphiphilic glycodynamers, which further self-ordered through supramolecular interactions into a 3D-network of biodynameric hydrogel. The synthetic pathway has been demonstrated by NMR and FTIR spectroscopy, X-ray diffraction and polarized light microscopy. Studies of the hydrogel morphology revealed a 3D porous microstructure, whose pores size correlated with the crosslinking degree. Rheological investigations evidenced high elasticity, thermo-responsiveness and thixotropic behavior. As a proof of the concept, the hydrogels proved in vivo biocompatibility on laboratory mice. The paper successfully implements the constitutional dynamic chemistry in generation of chitosan high performance hydrogels. Copyright © 2017 Elsevier Ltd. All rights reserved.

Supramolecular polyaniline hydrogel as a support for urease

International Nuclear Information System (INIS)

Słoniewska, Anna; Pałys, Barbara

2014-01-01

Supramolecular hydrogels of conducting polymers are successfully used in bioelectrochemistry because of their mechanical and swelling properties of gels added to the specific electron transport properties of conducting polymers. We have studied polyaniline-poly(styrene sulfonate) (PANI–PSS) hydrogel as a substrate for the urease. The hydrogels were synthesized at pH = 0 and pH = 5. PANI–PSS hydrogel is a supramolecular self-assembly material consisting of positively-charged PANI chains and negatively-charged PSS chains. The hydrogel was studied by cyclic voltammetry, infrared and Raman spectroscopy and Scanning Electron Microscopy (SEM). Raman spectra revealed presence of phenazine rings in the hydrogel structure. Phenazine rings form covalent cross-linkers contributing to the hydrogel mechanical stability. The covalent cross-linkers influence the cyclic voltammetry responses of the hydrogel in acidic media. We tested the activity of urease immobilized in the PANI–PSS hydrogel by the physical adsorption or by the covalent bonding with the carbodiimide reaction. The enzyme immobilized in hydrogels prepared at higher pH value reveals significantly higher sensitivity. The method of the enzyme immobilization has smaller impact on the sensitivity. All hydrogel sensors reveal largely higher sensitivity to urea comparing to urease immobilized in the typical electrochemically deposited PANI films. The sensitivity of urease covalently bond to the hydrogel obtained at pH = 5 was as high as 1693 μA/(mol dm 3 ). The sensor response was linear in the urea concentration range from 10 −4 to 7 × 10 −2 mol/dm 3

Synthesis and characterization of hyaluronic acid/human-like collagen hydrogels

International Nuclear Information System (INIS)

Zhang, Jingjing; Ma, Xiaoxuan; Fan, Daidi; Zhu, Chenhui; Deng, Jianjun; Hui, Junfeng; Ma, Pei

2014-01-01

Injectable hydrogel plays an important role in soft tissue filling and repair. We report an injectable hydrogel based on hyaluronic acid (HA) and human-like collagen (HLC), both with favorable biocompatibility and biodegradability. These two types of biomacromolecules were crosslinked with 1,4-butanediol diglycidyl ether to form a three-dimensional network. The redundant crosslinker was removed by dialysis and distillation. An HA-based hydrogel prepared by the same method was used as a control. The cytocompatibility was studied with a Cell Counting Kit-8 (CCK-8) test. Carbazole colorimetry was used to analyze the in vitro degradation rate. The histocompatibility was evaluated by hematoxylin and eosin (H and E) staining analysis and immunohistochemical analysis. The CCK-8 assay demonstrated that the HA/HLC hydrogel was less cytotoxic than the HA-based hydrogel and could promote baby hamster kidney cell (BHK) proliferation. The cell adhesion indicated that BHK could grow well on the surface of the materials and maintain good cell viability. The in vitro degradation test showed that the HA/HLC hydrogel had a longer degradation time and an excellent antienzyme ability. In vivo injection showed that there was little inflammatory response to HA/HLC after 1, 2, and 4 weeks. Therefore, the HA/HLC hydrogel is a promising biomaterial for soft tissue filling and repair. - Highlights: • Human-like collagen was used with hyaluronic acid to prepare soft tissue filling meterials. • 1,4-Butanediol diglycidyl ether (BDDE) was introduced to treat the hydrogels. • The addition of human-like collagen could improve the biological properties of hydrogels

Synthesis and characterization of hyaluronic acid/human-like collagen hydrogels

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jingjing; Ma, Xiaoxuan, E-mail: xiaoxuanma@163.com; Fan, Daidi, E-mail: fandaidi@nwu.edu.cn; Zhu, Chenhui; Deng, Jianjun; Hui, Junfeng; Ma, Pei

2014-10-01

Injectable hydrogel plays an important role in soft tissue filling and repair. We report an injectable hydrogel based on hyaluronic acid (HA) and human-like collagen (HLC), both with favorable biocompatibility and biodegradability. These two types of biomacromolecules were crosslinked with 1,4-butanediol diglycidyl ether to form a three-dimensional network. The redundant crosslinker was removed by dialysis and distillation. An HA-based hydrogel prepared by the same method was used as a control. The cytocompatibility was studied with a Cell Counting Kit-8 (CCK-8) test. Carbazole colorimetry was used to analyze the in vitro degradation rate. The histocompatibility was evaluated by hematoxylin and eosin (H and E) staining analysis and immunohistochemical analysis. The CCK-8 assay demonstrated that the HA/HLC hydrogel was less cytotoxic than the HA-based hydrogel and could promote baby hamster kidney cell (BHK) proliferation. The cell adhesion indicated that BHK could grow well on the surface of the materials and maintain good cell viability. The in vitro degradation test showed that the HA/HLC hydrogel had a longer degradation time and an excellent antienzyme ability. In vivo injection showed that there was little inflammatory response to HA/HLC after 1, 2, and 4 weeks. Therefore, the HA/HLC hydrogel is a promising biomaterial for soft tissue filling and repair. - Highlights: • Human-like collagen was used with hyaluronic acid to prepare soft tissue filling meterials. • 1,4-Butanediol diglycidyl ether (BDDE) was introduced to treat the hydrogels. • The addition of human-like collagen could improve the biological properties of hydrogels.

Electromechanical response of silk fibroin hydrogel and conductive polycarbazole/silk fibroin hydrogel composites as actuator material.

Science.gov (United States)

Srisawasdi, Thanida; Petcharoen, Karat; Sirivat, Anuvat; Jamieson, Alexander M

2015-11-01

Pure silk fibroin (SF) hydrogel and polycarbazole/silk fibroin (SF/PCZ) hydrogels were fabricated by solvent casting technique to evaluate electromechanical responses, dielectric properties, and cantilever deflection properties as functions of electric field strength, SF concentration, glutaraldehyde concentration, and PCZ concentration in the blends. Electromechanical properties were characterized in oscillatory shear mode at electric field strengths ranging from 0 to 600V/mm and at a temperature of 27°C. For both the pristine SF and SF/PCZ hydrogels, the storage modulus response (ΔG') and the storage modulus sensitivity (ΔG'/G'0) increased dramatically with increasing electric field strength. The pristine hydrogel possessed the highest storage modulus sensitivity value of 5.87, a relatively high value when compared with other previously studied electroactive polymers. With the addition of conductive PCZ in SF hydrogel, the storage modulus sensitivity and the relative dielectric constant decreased; the conductive polymer thus provided the softening effect under electric field. In the deflection response, the dielectrophoresis force and deflection distance increased monotonically with electric field strength, where the pure SF hydrogel showed the highest deflection distance and dielectrophoresis force. Copyright © 2015 Elsevier B.V. All rights reserved.

Injectable Thermoresponsive Hydrogel Formed by Alginate-g-Poly(N-isopropylacrylamide) That Releases Doxorubicin-Encapsulated Micelles as a Smart Drug Delivery System.

Science.gov (United States)

Liu, Min; Song, Xia; Wen, Yuting; Zhu, Jing-Ling; Li, Jun

2017-10-18

In this work, we have synthesized a thermoresponsive copolymer, alginate-g-poly(N-isopropylacrylamide) (alginate-g-PNIPAAm) by conjugating PNIPAAm to alginate, where PNIPAAm with different molecular weights and narrow molecular weight distribution was synthesized by atomic transfer radical polymerization. The copolymer dissolved in water or phosphate-buffered saline buffer solution at room temperature and formed self-assembled micelles with low critical micellization concentrations when the temperature increased to above their critical micellization temperatures. At higher concentration, that is, 7.4 wt % in water, the copolymer formed solutions at 25 °C and turned into thermosensitive hydrogels when temperature increased to the body temperature (37 °C). Herein, we hypothesized that the thermoresponsive hydrogels could produce self-assembled micelles with the dissolution of the alginate-g-PNIPAAm hydrogels in a biological fluid or drug release medium. If the drug was hydrophobic, the hydrogel eventually could release and produce drug-encapsulated micelles. In our experiments, we loaded the anticancer drug doxorubicin (DOX) into the alginate-g-PNIPAAm hydrogels and demonstrated that the hydrogels released DOX-encapsulated micelles in a sustained manner. The slowly released DOX-loaded micelles enhanced the cellular uptake of DOX in multidrug resistant AT3B-1 cells, showing the effect of overcoming the drug resistance and achieving better efficiency for killing the cancer cells. Therefore, the injectable thermoresponsive hydrogels formed by alginate-g-PNIPAAm and loaded with DOX turned into a smart drug delivery system, releasing DOX-encapsulated micelles in a sustained manner, showing great potential for overcoming the drug resistance in cancer therapy.

Poly(N-isopropylacrylamide)–poly(ferrocenylsilane) dual-responsive hydrogels: synthesis, characterization and antimicrobial applications

NARCIS (Netherlands)

Sui, Xiaofeng; Feng, Xueling; Di Luca, Andrea; van Blitterswijk, Clemens; Moroni, Lorenzo; Hempenius, Mark A.; Vancso, Gyula J.

2013-01-01

Novel hydrogels composed of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and redox-responsive poly(ferrocenylsilane) (PFS) macromolecules were formed by photopolymerization. PFS chains bearing acrylate side groups were copolymerized with NIPAM and N,N′-methylenebisacrylamide in

Drug release into hydrogel-based subcutaneous surrogates studied by UV imaging

DEFF Research Database (Denmark)

Ye, Fengbin; Larsen, Susan Weng; Yaghmur, Anan

2012-01-01

of the performance of drug delivery systems based on in vitro experiments. The objective of this study was to evaluate a UV imaging-based method for real-time characterization of the release and transport of piroxicam in hydrogel-based subcutaneous tissue mimics/surrogates. Piroxicam partitioning from medium chain...... upon the injection of aqueous or MCT solutions into an agarose-based hydrogel were investigated by UV imaging. The spatial distribution of piroxicam around the injection site in the gel matrix was monitored in real-time. The disappearance profiles of piroxicam from the injected aqueous solution were...... obtained. This study shows that the UV imaging methodology has considerable potential for characterizing transport properties in hydrogels, including monitoring the real-time spatial concentration distribution in vitro after administration by injection....

Glucose-Sensitive Hydrogel Optical Fibers Functionalized with Phenylboronic Acid.

Science.gov (United States)

Yetisen, Ali K; Jiang, Nan; Fallahi, Afsoon; Montelongo, Yunuen; Ruiz-Esparza, Guillermo U; Tamayol, Ali; Zhang, Yu Shrike; Mahmood, Iram; Yang, Su-A; Kim, Ki Su; Butt, Haider; Khademhosseini, Ali; Yun, Seok-Hyun

2017-04-01

Hydrogel optical fibers are utilized for continuous glucose sensing in real time. The hydrogel fibers consist of poly(acrylamide-co-poly(ethylene glycol) diacrylate) cores functionalized with phenylboronic acid. The complexation of the phenylboronic acid and cis-diol groups of glucose enables reversible changes of the hydrogel fiber diameter. The analyses of light propagation loss allow for quantitative glucose measurements within the physiological range. © 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cross-linkable graphene oxide embedded nanocomposite hydrogel with enhanced mechanics and cytocompatibility for tissue engineering.

Science.gov (United States)

Liu, Xifeng; Miller, A Lee; Waletzki, Brian E; Lu, Lichun

2018-05-01

Graphene oxide (GO) is an attractive material that can be utilized to enhance the modulus and conductivities of substrates and hydrogels. To covalently cross-link graphene oxide sheets into hydrogels, abundant cross-linkable double bonds were introduced to synthesize the graphene-oxide-tris-acrylate sheet (GO-TrisA). Polyacrylamide (PAM) nanocomposite hydrogels were then fabricated with inherent covalently and permanently cross-linked GO-TrisA sheets. Results showed that the covalently cross-linked GO-TrisA/PAM nanocomposite hydrogel had enhanced mechanical strength, thermo stability compared with GO/PAM hydrogel maintained mainly by hydrogen bonding between PAM chains and GO sheets. In vitro cell study showed that the covalently cross-linked rGO-TrisA/PAM nanocomposite hydrogel had excellent cytocompatibility after in situ reduction. These results suggest that rGO-TrisA/PAM nanocomposite hydrogel holds great potential for tissue engineering applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1247-1257, 2018. © 2018 Wiley Periodicals, Inc.

Membrane distillation with porous metal hollow fibers for the concentration of thermo-sensitive solutions

NARCIS (Netherlands)

Shukla, Sushumna

2014-01-01

This thesis presents an original approach for the concentration of thermo-sensitive solutions: the Sweep Gas Membrane Distillation (SGMD) process. A new membrane contactor with metallic hollow fibers has been designed and allows the distillation process to be operational at low temperature. Heat is

Extracellular Matrix Hydrogel Promotes Tissue Remodeling, Arteriogenesis, and Perfusion in a Rat Hindlimb Ischemia Model

Directory of Open Access Journals (Sweden)

Jessica L. Ungerleider, BS

2016-01-01

Full Text Available Although surgical and endovascular revascularization can be performed in peripheral arterial disease (PAD, 40% of patients with critical limb ischemia do not have a revascularization option. This study examines the efficacy and mechanisms of action of acellular extracellular matrix-based hydrogels as a potential novel therapy for treating PAD. We tested the efficacy of using a tissue-specific injectable hydrogel derived from decellularized porcine skeletal muscle (SKM and compared this to a new human umbilical cord-derived matrix (hUC hydrogel, which could have greater potential for tissue regeneration because of the younger age of the tissue source. In a rodent hindlimb ischemia model, both hydrogels were injected 1-week post-surgery and perfusion was regularly monitored with laser speckle contrast analysis to 35 days post-injection. There were significant improvements in hindlimb tissue perfusion and perfusion kinetics with both biomaterials. Histologic analysis indicated that the injected hydrogels were biocompatible, and resulted in arteriogenesis, rather than angiogenesis, as well as improved recruitment of skeletal muscle progenitors. Skeletal muscle fiber morphology analysis indicated that the muscle treated with the tissue-specific SKM hydrogel more closely matched healthy tissue morphology. Whole transcriptome analysis indicated that the SKM hydrogel caused a shift in the inflammatory response, decreased cell death, and increased blood vessel and muscle development. These results show the efficacy of an injectable ECM hydrogel alone as a potential therapy for treating patients with PAD. Our results indicate that the SKM hydrogel improved functional outcomes through stimulation of arteriogenesis and muscle progenitor cell recruitment.

Thermo-mechanical analysis of an acceleration grid for the international thermonuclear experimental reactor-neutral beam injection system

International Nuclear Information System (INIS)

Fujiwara, Yukio; Hanada, Masaya; Okumura, Yoshikazu; Suzuki, Satoshi; Watanabe, Kazuhiro

2001-01-01

In the engineering design of a negative-ion beam source for a high-power neutral beam injection (NBI) system, one of the most important issues is thermo-mechanical design of acceleration grids for producing several tens of MW ion beams. An acceleration grid for the international thermonuclear experimental reactor-neutral beam injection (ITER-NBI) system will be subjected to the heat loading as high as 1.5 MW. In the present paper, thermo-mechanical characteristics of the acceleration grid for the ITER-NBI system were analyzed. Numerical simulation indicated that maximum aperture-axis displacement of the acceleration grid due to thermal expansion would be about 0.7 mm for the heat loading of 1.5 MW. From the thin lens theory of beam optics, beamlet deflection angle by the aperture-axis displacement was estimated to be about 2 mrad, which is within the requirement of the engineering design of the ITER-NBI system. Numerical simulation also indicated that no melting on the acceleration grid would occur for a heat loading of 1.5 MW, while local plastic deformation would happen. To avoid the plastic deformation, it is necessary to reduce the heat loading onto the acceleration grid to less than 1 MW

Thermo-sensitive polymer nanospheres as a smart plugging agent for shale gas drilling operations.

Science.gov (United States)

Wang, Wei-Ji; Qiu, Zheng-Song; Zhong, Han-Yi; Huang, Wei-An; Dai, Wen-Hao

2017-01-01

Emulsifier-free poly(methyl methacrylate-styrene) [P(MMA-St)] nanospheres with an average particle size of 100 nm were synthesized in an isopropyl alcohol-water medium by a solvothermal method. Then, through radical graft copolymerization of thermo-sensitive monomer N -isopropylacrylamide (NIPAm) and hydrophilic monomer acrylic acid (AA) onto the surface of P(MMA-St) nanospheres at 80 °C, a series of thermo-sensitive polymer nanospheres, named SD-SEAL with different lower critical solution temperatures (LCST), were prepared by adjusting the mole ratio of NIPAm to AA. The products were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, particle size distribution, and specific surface area analysis. The temperature-sensitive behavior was studied by light transmittance tests, while the sealing performance was investigated by pressure transmission tests with Lungmachi Formation shales. The experimental results showed that the synthesized nanoparticles are sensitive to temperature and had apparent LCST values which increased with an increase in hydrophilic monomer AA. When the temperature was higher than its LCST value, SD-SEAL played a dual role of physical plugging and chemical inhibition, slowed down pressure transmission, and reduced shale permeability remarkably. The plugged layer of shale was changed to being hydrophobic, which greatly improved the shale stability.

Oral delivery of insulin using pH-sensitive hydrogels based on polyvinyl alcohol grafted with acrylic acid/methacrylic acid by radiation

Energy Technology Data Exchange (ETDEWEB)

Nho, Young-Chang [Radiation Application Research Division, Korea Atomic Energy Research Institute, Daejeon 305-600 (Korea, Republic of)]. E-mail: ycnho@kaeri.re.kr; Park, Sung-Eun [Radiation Application Research Division, Korea Atomic Energy Research Institute, Daejeon 305-600 (Korea, Republic of); Kim, Hyung-Il [College of Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of); Hwang, Taek-Sung [College of Engineering, Chungnam National University, Daejeon 305-764 (Korea, Republic of)

2005-07-01

The pH-responsive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing in the small intestine. Hydrogels based on poly(vinyl alcohol) networks grafted with acrylic acid or methacrylic acid were prepared via a two-step process. Poly(vinyl alcohol) hydrogels were prepared by gamma ray irradiation (50 kGy) and then followed by grafting either acrylic acid or methacrylic acid onto this poly(vinyl alcohol) hydrogels with subsequent irradiation (5-20 kGy). These graft hydrogels showed pH-sensitive swelling behavior. These hydrogels were used as carrier for the controlled release of insulin. The in vitro release of insulin was observed for the insulin-loaded hydrogels in a simulated intestinal fluid (pH 6.8) but not in a simulated gastric fluid (pH 1.2). The release behavior of insulin in vivo in a rat model confirmed the effectiveness of the oral delivery of insulin to control the level of glucose.

Oral delivery of insulin using pH-sensitive hydrogels based on polyvinyl alcohol grafted with acrylic acid/methacrylic acid by radiation

International Nuclear Information System (INIS)

Nho, Young-Chang; Park, Sung-Eun; Kim, Hyung-Il; Hwang, Taek-Sung

2005-01-01

The pH-responsive hydrogels were studied as a drug carrier for the protection of insulin from the acidic environment of the stomach before releasing in the small intestine. Hydrogels based on poly(vinyl alcohol) networks grafted with acrylic acid or methacrylic acid were prepared via a two-step process. Poly(vinyl alcohol) hydrogels were prepared by gamma ray irradiation (50 kGy) and then followed by grafting either acrylic acid or methacrylic acid onto this poly(vinyl alcohol) hydrogels with subsequent irradiation (5-20 kGy). These graft hydrogels showed pH-sensitive swelling behavior. These hydrogels were used as carrier for the controlled release of insulin. The in vitro release of insulin was observed for the insulin-loaded hydrogels in a simulated intestinal fluid (pH 6.8) but not in a simulated gastric fluid (pH 1.2). The release behavior of insulin in vivo in a rat model confirmed the effectiveness of the oral delivery of insulin to control the level of glucose

Heparin-Poloxamer Thermosensitive Hydrogel Loaded with bFGF and NGF Enhances Peripheral Nerve Regeneration in Diabetic Rats.

Science.gov (United States)

Li, Rui; Li, Yiyang; Wu, Yanqing; Zhao, Yingzheng; Chen, Huanwen; Yuan, Yuan; Xu, Ke; Zhang, Hongyu; Lu, Yingfeng; Wang, Jian; Li, Xiaokun; Jia, Xiaofeng; Xiao, Jian

2018-06-01

Peripheral nerve injury (PNI) is a major burden to society with limited therapeutic options, and novel biomaterials have great potential for shifting the current paradigm of treatment. With a rising prevalence of chronic illnesses such as diabetes mellitus (DM), treatment of PNI is further complicated, and only few studies have proposed therapies suitable for peripheral nerve regeneration in DM. To provide a supportive environment to restore structure and/or function of nerves in DM, we developed a novel thermo-sensitive heparin-poloxamer (HP) hydrogel co-delivered with basic fibroblast growth factor (bFGF) and nerve growth factor (NGF) in diabetic rats with sciatic nerve crush injury. The delivery vehicle not only had a good affinity for large amounts of growth factors (GFs), but also controlled their release in a steady fashion, preventing degradation in vitro. In vivo, compared with HP hydrogel alone or direct GFs administration, GFs-HP hydrogel treatment is more effective at facilitating Schwann cell (SC) proliferation, leading to an increased expression of nerve associated structural proteins, enhanced axonal regeneration and remyelination, and improved recovery of motor function (all p nerve regeneration in patients with DM. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydrogel-based piezoresistive sensor for the detection of ethanol

Directory of Open Access Journals (Sweden)

J. Erfkamp

2018-04-01

Full Text Available This article describes a low-cost sensor for the detection of ethanol in alcoholic beverages, which combines alcohol-sensitive hydrogels based on acrylamide and bisacrylamide and piezoresistive sensors. For reproducible measurements, the reversible swelling and deswelling of the hydrogel were shown via microscopy. The response time of the sensor depends on the swelling kinetics of the hydrogel. The selectivity of the hydrogel was tested in different alcohols. In order to understand the influence of monomer and crosslinker content on the swelling degree and on the sensitivity of the hydrogels, gels with variable concentrations of acrylamide and bisacrylamide were synthesized and characterized in different aqueous solutions with alcohol contents. The first measurements of such hydrogel-based piezoresistive ethanol sensors demonstrated a high sensitivity and a short response time over several measuring cycles.

Preparation and swelling properties of pH-sensitive composite hydrogel beads based on chitosan-g-poly (acrylic acid)/vermiculite and sodium alginate for diclofenac controlled release.

Science.gov (United States)

Wang, Qin; Xie, Xiaoling; Zhang, Xiaowei; Zhang, Junping; Wang, Aiqin

2010-04-01

A series of pH-sensitive composite hydrogel beads, chitosan-g-poly (acrylic acid)/vermiculite/sodium alginate (CTS-g-PAA/VMT/SA), was prepared using CTS-g-PAA/VMT composite and SA by Ca(2+) as the crosslinking agent. The structure and morphologies of the developed composite hydrogel beads were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The swelling properties and pH-sensitivity of the beads were investigated. In addition, the drug loading and controlled release behaviors of the beads were also evaluated using diclofenac sodium (DS) as the model drug in stimulated gastric fluids (pH 2.1) and intestinal fluids (pH 6.8). The results indicate that the composite hydrogel beads showed good pH-sensitivity. The release rate of the drug from the composite hydrogel beads is remarkably slowed down, which indicated that incorporating VMT into the composite hydrogel beads can improve the burst release effect of the drug. Copyright 2010 Elsevier B.V. All rights reserved.

Gamma radiation synthesis of super absorbent hydrogels for different applications

International Nuclear Information System (INIS)

Marzouk, H.M.G.

2015-01-01

Super absorbent polymers (SAP) of carboxymethyl cellulose/acrylamide (CMC/PAM), carboxymethyl cellulose/acrylamide/Silica (CMC/AM/Si) and carboxymethyl cellulose/Polyvinyl alcohol (CMC/PVA) were synthesized by radiation-induced grafting using γ-irradiation technique. The effects of various parameters, such as irradiation dose, the content of CMC, PAM, PVA, and Silica gel on the swelling percent of produced hydrogels have been evaluated. The kinetic equilibrium swelling of the prepared copolymer hydrogels was studied, it was found that the maximum swelling percent was 5000 % for the CMC/PAM hydrogel, 12000 % for the CMC/PAM/Si composite hydrogel, and 6200 % for the CMC/PVA hydrogel. The gel fraction, equilibrium swelling and effect of ph on the swelling percent were also studied. The prepared copolymers were also characterized by FTIR spectral analysis, thermo gravimetric analysis (TGA), and scanning electron microscopy (SEM) techniques. In order to evaluate its controlled release potential, different prepared hydrogels were loaded with KNO 3 as an agrochemical model and its potential for controlled release of KNO 3 was studied and evaluated with respect to different parameters such as time of release, ph of the medium, and temperatures. The results obtained from swelling, loading of KNO 3 , and release behavior studies suggested and recommended the possible use of prepared hydrogels for enhancing the plantation of Linum Usitatissimum.

Drug delivery system of basic fibroblast growth factor using gelatin hydrogel for restoration of acute vocal fold scar.

Science.gov (United States)

Kobayashi, Toshiki; Mizuta, Masanobu; Hiwatashi, Nao; Kishimoto, Yo; Nakamura, Tatsuo; Kanemaru, Shin-Ichi; Hirano, Shigeru

2017-02-01

There continue to be therapeutic challenges in the management of vocal fold scarring. We previously showed that basic fibroblast growth factor (bFGF) injection has therapeutic potential for vocal fold scarring. However, the working time of bFGF is relatively short, and multiple injections were required in many cases to obtain the regenerative effect. An efficacious delivery system for bFGF has yet to be established. We designed a method of sustained drug delivery system (DDS) of bFGF by using a gelatin hydrogel. Hydrogel has been developed for targeted delivery and controlled release of bFGF. Hydrogel of the particle type is also injectable and commercially available. The current study aims to investigate the effects of a single injection of bFGF-DDS on acute vocal fold scarring using a canine model. Vocal folds from eight beagles were unilaterally scarred by stripping the lamina propria. One month later, hydrogels (0.5ml) containing 10μg of bFGF were injected into the scarred vocal folds of four beagles (FGF-hydrogel group). Saline (0.5ml) was injected into the other four beagles (sham group). Vibratory and histological examination of excised larynges was performed 5 months after treatment. Comparative analysis between the current data and our previous data with repeated injection of bFGF solution was also completed. Vibratory examination demonstrated significantly improved vibration in the bFGF hydrogel-treated group. Histological examination of the bFGF hydrogel group showed restoration of hyaluronic acid in the lamina propria as compared to sham. Comparison between the DDS system and our previous bFGF solution injection indicated better effects of the DDS system on vibratory amplitude. A single injection of bFGF hydrogel has regenerative effects on acute vocal fold scarring, which is at least similar to repeated injection of bFGF solution. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Magnetic hyaluronate hydrogels: preparation and characterization

International Nuclear Information System (INIS)

Tóth, Ildikó Y.; Veress, Gábor; Szekeres, Márta; Illés, Erzsébet; Tombácz, Etelka

2015-01-01

A novel soft way of hyaluronate (HyA) based magnetic hydrogel preparation was revealed. Magnetite nanoparticles (MNPs) were prepared by co-precipitation. Since the naked MNPs cannot be dispersed homogenously in HyA-gel, their surface was modified with natural and biocompatible chondroitin-sulfate-A (CSA) to obtain CSA-coated MNPs (CSA@MNPs). The aggregation state of MNPs and that loaded with increasing amount of CSA up to 1 mmol/g was measured by dynamic light scattering at pH~6. Only CSA@MNP with ≥0.2 mmol/g CSA content was suitable for magnetic HyA-gel preparation. Rheological studies showed that the presence of CSA@MNP with up to 2 g/L did not affect the hydrogel's rheological behavior significantly. The results suggest that the HyA-based magnetic hydrogels may be promising formulations for future biomedical applications, e.g. as intra-articular injections in the treatment of osteoarthritis. - Highlights: • Novel hyaluronate(HyA)-based biocompatible magnetic hydrogels were prepared. • Chondroitin-sulfate-A coating is needed to disperse magnetite particles in HyA-gel. • Rheological behavior of hydrogels was independent of the magnetite content (<2 g/L). • Gels remained in stable and homogeneously dispersed state even after 90 days storage. • Magnetic HyA-gels are promising candidates for use as intra-articular injection

Magnetic hyaluronate hydrogels: preparation and characterization

Energy Technology Data Exchange (ETDEWEB)

Tóth, Ildikó Y., E-mail: Ildiko.Toth@chem.u-szeged.hu; Veress, Gábor; Szekeres, Márta; Illés, Erzsébet; Tombácz, Etelka, E-mail: tombacz@chem.u-szeged.hu

2015-04-15

A novel soft way of hyaluronate (HyA) based magnetic hydrogel preparation was revealed. Magnetite nanoparticles (MNPs) were prepared by co-precipitation. Since the naked MNPs cannot be dispersed homogenously in HyA-gel, their surface was modified with natural and biocompatible chondroitin-sulfate-A (CSA) to obtain CSA-coated MNPs (CSA@MNPs). The aggregation state of MNPs and that loaded with increasing amount of CSA up to 1 mmol/g was measured by dynamic light scattering at pH~6. Only CSA@MNP with ≥0.2 mmol/g CSA content was suitable for magnetic HyA-gel preparation. Rheological studies showed that the presence of CSA@MNP with up to 2 g/L did not affect the hydrogel's rheological behavior significantly. The results suggest that the HyA-based magnetic hydrogels may be promising formulations for future biomedical applications, e.g. as intra-articular injections in the treatment of osteoarthritis. - Highlights: • Novel hyaluronate(HyA)-based biocompatible magnetic hydrogels were prepared. • Chondroitin-sulfate-A coating is needed to disperse magnetite particles in HyA-gel. • Rheological behavior of hydrogels was independent of the magnetite content (<2 g/L). • Gels remained in stable and homogeneously dispersed state even after 90 days storage. • Magnetic HyA-gels are promising candidates for use as intra-articular injection.

Sorption of zinc by novel pH-sensitive hydrogels based on chitosan, itaconic acid and methacrylic acid

International Nuclear Information System (INIS)

Milosavljevic, Nedeljko B.; Ristic, Mirjana D.; Peric-Grujic, Aleksandra A.; Filipovic, Jovanka M.; Strbac, Svetlana B.; Rakocevic, Zlatko Lj.; Kalagasidis Krusic, Melina T.

2011-01-01

Highlights: → A removal of Zn 2+ ions by pH-sensitive Ch/IA/MAA hydrogel from aqueous solutions was studied. → SEM/EDX analysis and AFM surface topography indicate that sorption takes place on the surface of the hydrogel and in the bulk. → FTIR spectra of the Ch/IA/MAA hydrogel, free and Zn-loaded, indicate that -NH 2 , -OH and -COOH groups are involved in the sorption process. → The negative values of free energy and enthalpy indicated that the adsorption is spontaneous and exothermic one. → The adsorption capacities did not show any significant decrease after the third reuse cycle. - Abstract: Novel pH-sensitive hydrogels based on chitosan, itaconic acid and methacrylic acid were applied as adsorbents for the removal of Zn 2+ ions from aqueous solution. In batch tests, the influence of solution pH, contact time, initial metal ion concentration and temperature was examined. The sorption was found pH dependent, pH 5.5 being the optimum value. The adsorption process was well described by the pseudo-second order kinetic. The hydrogels were characterized by spectral (Fourier transform infrared-FTIR) and structural (SEM/EDX and atomic force microscopy-AFM) analyses. The surface topography changes were observed by atomic force microscopy, while the changes in surface composition were detected using phase imaging AFM. The negative values of free energy and enthalpy indicated that the adsorption is spontaneous and exothermic one. The best fitting isotherms were Langmuir and Redlich-Peterson and it was found that both linear and nonlinear methods were appropriate for obtaining the isotherm parameters. However, the increase of temperature leads to higher adsorption capacity, since swelling degree increased with temperature.

Development of polymer-polysaccharide hydrogels for controlling drug delivery

Science.gov (United States)

Baldwin, Aaron David

The use of polymers as biomaterials has evolved over the past several decades, encompassing an expanding synthetic toolbox and many bio-mimetic approaches. Both synthetic and natural polymers have been used as components for biomaterials as their unique chemical structures can provide specific functions for desired applications. Of these materials, heparin, a highly sulfated naturally occurring polysaccharide, has been investigated extensively as a core component in drug delivery platforms and tissue engineering. The goal of this work was to further explore the use of heparin via conjugation with synthetic polymers for applications in drug delivery. We begin by investigating low molecular weight heparin (LMWH), a depolymerized heparin that is used medicinally in the prevention of thrombosis by subcutaneous injection or intravenous drip. Certain disease states or disorders require frequent administration with invasive delivery modalities leading to compliance issues for individuals on prolonged therapeutic courses. To address these issues, a long-term delivery method was developed for LMWH via subcutaneous injection of in situ hydrogelators. This therapy was accomplished by chemical modification of LMWH with maleimide functionality so that it may be crosslinked into continuous hydrogel networks with four-arm thiolated polyethylene glycol (PEG-SH). These hydrogels degrade via hydrolysis over a period of weeks and release bioactive LMWH with first-order kinetics as determined by in vitro and in vivo models, thus indicating the possibility of an alternative means of heparin delivery over current accepted methodologies. Evaluation of the maleimide-thiol chemistries applied in the LMWH hydrogels revealed reversibility for some conjugates under reducing conditions. Addition chemistries, such as maleimide-thiol reactions, are widely employed in biological conjugates and are generally accepted as stable. Here we show that the resulting succinimide thioether formed by the

Stimuli-responsive hydrogels in drug delivery and tissue engineering.

Science.gov (United States)

Sood, Nikhil; Bhardwaj, Ankur; Mehta, Shuchi; Mehta, Abhinav

2016-01-01

Hydrogels are the three-dimensional network structures obtained from a class of synthetic or natural polymers which can absorb and retain a significant amount of water. Hydrogels are one of the most studied classes of polymer-based controlled drug release. These have attracted considerable attention in biochemical and biomedical fields because of their characteristics, such as swelling in aqueous medium, biocompatibility, pH and temperature sensitivity or sensitivity towards other stimuli, which can be utilized for their controlled zero-order release. The hydrogels are expected to explore new generation of self-regulated delivery system having a wide array of desirable properties. This review highlights the exciting opportunities and challenges in the area of hydrogels. Here, we review different literatures on stimuli-sensitive hydrogels, such as role of temperature, electric potential, pH and ionic strength to control the release of drug from hydrogels.

Injectable nanocomposite cryogels for versatile protein drug delivery.

Science.gov (United States)

Koshy, Sandeep T; Zhang, David K Y; Grolman, Joshua M; Stafford, Alexander G; Mooney, David J

2018-01-01

Sustained, localized protein delivery can enhance the safety and activity of protein drugs in diverse disease settings. While hydrogel systems are widely studied as vehicles for protein delivery, they often suffer from rapid release of encapsulated cargo, leading to a narrow duration of therapy, and protein cargo can be denatured by incompatibility with the hydrogel crosslinking chemistry. In this work, we describe injectable nanocomposite hydrogels that are capable of sustained, bioactive, release of a variety of encapsulated proteins. Injectable and porous cryogels were formed by bio-orthogonal crosslinking of alginate using tetrazine-norbornene coupling. To provide sustained release from these hydrogels, protein cargo was pre-adsorbed to charged Laponite nanoparticles that were incorporated within the walls of the cryogels. The presence of Laponite particles substantially hindered the release of a number of proteins that otherwise showed burst release from these hydrogels. By modifying the Laponite content within the hydrogels, the kinetics of protein release could be precisely tuned. This versatile strategy to control protein release simplifies the design of hydrogel drug delivery systems. Here we present an injectable nanocomposite hydrogel for simple and versatile controlled release of therapeutic proteins. Protein release from hydrogels often requires first entrapping the protein in particles and embedding these particles within the hydrogel to allow controlled protein release. This pre-encapsulation process can be cumbersome, can damage the protein's activity, and must be optimized for each protein of interest. The strategy presented in this work simply premixes the protein with charged nanoparticles that bind strongly with the protein. These protein-laden particles are then placed within a hydrogel and slowly release the protein into the surrounding environment. Using this method, tunable release from an injectable hydrogel can be achieved for a variety of

Kinetic investigation and lifetime prediction of Cs-NIPAM-MBA-based thermo-responsive hydrogels.

Science.gov (United States)

Othman, Muhammad Bisyrul Hafi; Khan, Abbas; Ahmad, Zulkifli; Zakaria, Muhammad Razlan; Ullah, Faheem; Akil, Hazizan Md

2016-01-20

This study attempted to clarify the influence of a cross-linker, N,N-methylenebisacrylamide (MBA), and N-isopropylacrylamide (NIPAM) on the non-isothermal kinetic degradation, solid state and lifetime of hydrogels using the Flynn-Wall-Ozawa (F-W-O), Kissinger, and Coats-Redfern (C-Red) methods. The series of dual-responsive Cs-PNIPAM-MBA microgels were synthesized by soapless-emulsion free radical copolymerization in an aqueous medium at 70 °C. The thermal properties were investigated using thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) under nitrogen atmosphere. The apparent activation energy using the chosen Flynn-Wall-Ozawa and Kissinger methods showed that they fitted each other. Meanwhile, the type of solid state mechanism was determined using the Coats-Redfern method proposed for F1 (pure Cs) and F2 (Cs-PNIPAM-MBA hydrogel series) types, which comprise random nucleation with one nucleus reacting on individual particles, and random nucleation with two nuclei reacting on individual particles, respectively. On average, a higher Ea was attributed to the greater cross-linking density of the Cs hydrogel. Copyright © 2015 Elsevier Ltd. All rights reserved.

Design and development of guar gum based novel, superabsorbent and moisture retaining hydrogels for agricultural applications.

Science.gov (United States)

Thombare, Nandkishore; Mishra, Sumit; Siddiqui, M Z; Jha, Usha; Singh, Deodhari; Mahajan, Gopal R

2018-04-01

The novel hydrogels were synthesized by grafting guar gum with acrylic acid and cross-linking with ethylene glycol di methacrylic acid (EGDMA). The synthesis of hydrogel was confirmed by characterization through 13 C NMR, FTIR spectroscopy, SEM micrography, thermo-gravimetric analysis and water absorption studies under different solutions. Synthesized hydrogel (GG-AA-EGDMA) was confirmed to be biodegradable with half-life period of 77 days through soil burial biodegradation studies. The effects of hydrogel treatment on soil were evaluated by studying various physico-chemical properties of soil like bulk density, porosity, water absorption and retention capacity etc. The hydrogel which could absorb up to 800 ml water per gram, after addition to soil, improved its porosity, moisture absorption and retention capacity significantly. Water holding capacity of water increased up to 54% of its original and porosity also increased up to 9% of its original. The synthesized hydrogel revealed tremendous potential as soil conditioning material for agricultural applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

Triply responsive films in bioelectrocatalysis with a binary architecture: combined layer-by-layer assembly and hydrogel polymerization.

Science.gov (United States)

Yao, Huiqin; Hu, Naifei

2011-05-26

In this work, triply responsive films with a specific binary architecture combining layer-by-layer assembly (LbL) and hydrogel polymerization were successfully prepared. First, concanavalin A (Con A) and dextran (Dex) were assembled into {Con A/Dex}(5) LbL layers on electrode surface by the lectin-sugar biospecific interaction between them. The poly(N,N-diethylacrylamide) (PDEA) hydrogels with entrapped horseradish peroxidase (HRP) were then synthesized by polymerization on the surface of LbL inner layers, forming {Con A/Dex}(5)-(PDEA-HRP) films. The films demonstrated reversible pH-, thermo-, and salt-responsive on-off behavior toward electroactive probe Fe(CN)(6)(3-) in its cyclic voltammetric responses. This multiple stimuli-responsive films could be further used to realize triply switchable electrochemical reduction of H(2)O(2) catalyzed by HRP immobilized in the films and mediated by Fe(CN)(6)(3-) in solution. The responsive mechanism of the films was explored and discussed. The pH-sensitive property of the system was attributed to the electrostatic interaction between the {Con A/Dex}(5) inner layers and the probe at different pH, and the thermo- and salt-responsive behaviors should be ascribed to the structure change of PDEA hydrogels for the PDEA-HRP outermost layers under different conditions. The concept of binary architecture was also used to fabricate {Con A/Dex}(5)-(PDEA-GOD) films on electrodes, where GOD = glucose oxidase, which was applied to realize the triply switchable bioelectrocatalysis of glucose by GOD in the films with ferrocenedicarboxylic acid as the mediator in solution. This film system with the unique binary architecture may establish a foundation for fabricating a novel type of multicontrollable biosensors based on bioelectrocatalysis with immobilized enzymes.

Nonthrombotic Pulmonary Embolism: A Potential Complication of Polyacrylamide Hydrogel Cosmetic Injection

Directory of Open Access Journals (Sweden)

Faisal Inayat

2016-01-01

Full Text Available Context. Polyacrylamide hydrogel (PAAG has gained importance as a synthetic soft tissue filling agent. It has been commonly employed by physicians in Europe for facial contouring and soft tissue augmentation. Previously, PAAG is considered nontoxic and well tolerated with a few mild procedural complications. Case Presentation. A 26-year-old female was hospitalized for dry cough, worsening dyspnea, and chest discomfort after 3 hours of multiple PAAG injections in buttocks. The patient’s condition deteriorated and rapidly advanced to acute respiratory failure. Therein, the diagnosis of nonthrombotic pulmonary embolism (NTPE was established on standard set of investigations. She was intubated; corticosteroid and empiric antibiotic therapy was initiated resulting in improvement of her condition. Subsequently, extubation was done, and she was discharged from the hospital after an uneventful recovery. On 1-month follow-up, the patient had no previous symptoms. Conclusion. This report implicates clinicians to maintain a high index of suspicion for NTPE in patients presenting with respiratory symptoms following PAAG usage.

3D- Printed Poly(ε-caprolactone) Scaffold Integrated with Cell-laden Chitosan Hydrogels for Bone Tissue Engineering.

Science.gov (United States)

Dong, Liang; Wang, Shao-Jie; Zhao, Xin-Rong; Zhu, Yu-Fang; Yu, Jia-Kuo

2017-10-17

Synthetic polymeric scaffolds are commonly used in bone tissue engineering (BTE) due to their biocompatibility and adequate mechanical properties. However, their hydrophobicity and the lack of specific cell recognition sites confined their practical application. In this study, to improve the cell seeding efficiency and osteoinductivity, an injectable thermo-sensitive chitosan hydrogel (CSG) was incorporated into a 3D-printed poly(ε-caprolactone) (PCL) scaffold to form a hybrid scaffold. To demonstrate the feasibility of this hybrid system for BTE application, rabbit bone marrow mesenchymal stem cells (BMMSCs) and bone morphogenetic protein-2 (BMP-2) were encapsulated in CSG. Pure PCL scaffolds were used as controls. Cell proliferation and viability were investigated. Osteogenic gene expressions of BMMSCs in various scaffolds were determined with reverse transcription polymerase chain reaction (RT-PCR). Growth factor releasing profile and mechanical tests were performed. CCK-8 assay confirmed greater cell retention and proliferation in chitosan and hybrid groups. Confocal microscopy showed even distribution of cells in the hybrid system. After 2-week osteogenic culture in vitro, BMMSCs in hybrid and chitosan scaffolds showed stronger osteogenesis and bone-matrix formation. To conclude, chitosan/PCL hybrid scaffolds are a favorable platform for BTE due to its capacity to carry cells and drugs, and excellent mechanical strength.

Thermo-elastic optical coherence tomography

NARCIS (Netherlands)

Wang, Tianshi; Pfeiffer, Tom; Wu, Min; Wieser, Wolfgang; Amenta, Gaetano; Draxinger, Wolfgang; van der Steen, A.F.W.; Huber, Robert; Van Soest, Gijs

2017-01-01

The absorption of nanosecond laser pulses induces rapid thermo-elastic deformation in tissue. A sub-micrometer scale displacement occurs within a few microseconds after the pulse arrival. In this Letter, we investigate the laser-induced thermo-elastic deformation using a 1.5 MHz phase-sensitive

A hydrogel biosensor for high selective and sensitive detection of amyloid-beta oligomers

Directory of Open Access Journals (Sweden)

Sun LP

2018-02-01

Full Text Available Liping Sun,1 Yong Zhong,1 Jie Gui,1 Xianwu Wang,1 Xiaorong Zhuang,2 Jian Weng1 1Key Laboratory of Biomedical Engineering of Fujian Province, Research Center of Biomedical Engineering of Xiamen, Department of Biomaterials, College of Materials, Xiamen University, 2Department of Neurology, The Affiliated Zhongshan Hospital of Xiamen University, Xiamen, People’s Republic of China Background: Alzheimer’s disease (AD is a neurodegenerative disorder characterized by progressive cognitive and memory impairment. It is the most common neurological disease that causes dementia. Soluble amyloid-beta oligomers (AβO in blood or cerebrospinal fluid (CSF are the pathogenic biomarker correlated with AD. Methods: A simple electrochemical biosensor using graphene oxide/gold nanoparticles (GNPs hydrogel electrode was developed in this study. Thiolated cellular prion protein (PrPC peptide probe was immobilized on GNPs of the hydrogel electrode to construct an AβO biosensor. Electrochemical impedance spectroscopy was utilized for AβO analysis. Results: The specific binding between AβO and PrPC probes on the hydrogel electrode resulted in an increase in the electron-transfer resistance. The biosensor showed high specificity and sensitivity for AβO detection. It could selectively differentiate AβO from amyloid-beta (Aβ monomers or fibrils. Meanwhile, it was highly sensitive to detect as low as 0.1 pM AβO in artificial CSF or blood plasma. The linear range for AβO detection is from 0.1 pM to 10 nM. Conclusion: This biosensor could be used as a cost-effective tool for early diagnosis of AD due to its high electrochemical performance and bionic structure. Keywords: Alzheimer’s disease, amyloid-beta oligomer, graphene, gold nanoparticles, biosensor

Thermo-hydraulic behavior of saturated steam-water mixture in pressure vessel during injection of cold water

International Nuclear Information System (INIS)

Aya, Izuo; Kobayashi, Michiyuki; Inasaka, Fujio; Nariai, Hideki.

1983-01-01

The thermo-hydraulic behavior of saturated steam water mixture in a pressure vessel during injection of cold water was experimentally investigated with the Facility for Mixing Effect of Emergency Core Cooling Water. The dimensions of the pressure vessel used in the experiments were 284mm ID and 1,971mm height. 11 experiments were conducted without blowdown in order to comprehend the basic process excluding the effect of blowdown at injection of cold water. The initial pressure and water level, the injection flow rate and the size of injection nozzle were chosen as experimental parameters. Temperatures and void fractions at 6 elevations as well as pressure in the pressure vessel were measured, and new data especially on the pressure undershoot just after the initation of water injection and the vertical distribution of temperature and void fraction were gotten. The transients of pressure, average temperature and void fraction were caluculated using single-volume analysis code BLODAC-1V which is based on thermal equilibrium and so-called bubble gradient model. Some input parameters included in the analysis code were evaluated through the comparison of analysis with experimental data. Moreover, the observed pressure undershoot which is evaluated to be induced by a time lag of vapourization in water due to thermal nonequilibrium, was also discussed with the aid of another simple analysis model. (author)

Effects of upper plenum injection on thermo-hydrodynamic behavior under refill and reflood phases

International Nuclear Information System (INIS)

Iwamura, Takamichi; Sobajima, Makoto; Abe, Yutaka; Adachi, Hiromichi; Ohnuki, Akira; Osakabe, Masahiro

1984-12-01

In order to investigate the thermo-hydrodynamic behavior in core under simultaneous ECC water injection into the upper plenum and the intact cold leg during the refill and reflood phases of a PWR-LOCA, Tests S1-SH3 and S1-SH4 were performed by using Slab Core Test Facility (SCTF) with the injection of saturated and 67K subcooled water into the upper plenum, respectively, under the same cold leg injection condition. The following major findings were obtained by examining these test results. (1) Although the core was cooled by the fall back water from the upper plenum into the core during the period of high injection rate into the upper plenum, the core was cooled mainly by the bottom flooding after the BOCREC (Bottom of core recovery). (2) The possible fall back flow rate estimated with a CCFL correlation rapidly decreased after the BOCREC because of the increase of steam generation rate in core. (3) Continuous fall back of subcooled water was not observed even under the condition with large upper plenum injection rate of subcooled water and with steam outflow through the lower plenum into the downcomer. The fall back was intermittently limited by the rapid increase of upward steam flow which was generated in the core due to the evaporation of the fall back water. (4) The rising of liquid level in the lower plenum was suppressed by the pressurization in core due to the evaporation of fall back water before the BOCREC and therefore the beginning of bottom reflood was delayed. Some selected data from Tests S1-SH3 and S1-SH4 are also included in this report. (author)

Physicochemical properties of pH-sensitive hydrogels based on hydroxyethyl cellulose-hyaluronic acid and for applications as transdermal delivery systems for skin lesions.

Science.gov (United States)

Kwon, Soon Sik; Kong, Bong Ju; Park, Soo Nam

2015-05-01

We investigated the physicochemical properties of pH-sensitive hydroxyethyl cellulose (HEC)/hyaluronic acid (HA) complex hydrogels containing isoliquiritigenin (ILTG), and discussed potential applications as transdermal delivery systems for the treatment of skin lesions caused by pH imbalance. HA has skin compatibility and pH functional groups and HEC serves as scaffold to build hydrogels with varied HCE:HA mass ratio. Hydrogels were synthesized via chemical cross-linking, and three-dimensional network structures were characterized via scanning electron microscopy (SEM). The swelling properties and polymer ratios of the hydrogels were investigated at pH values in the range 1-13. HECHA13 (i.e., an HEC:HA mass ratio of 1:3) was found to have optimal rheological and adhesive properties, and was used to investigate the drug release efficiency as a function of pH; the efficiency was greater than 70% at pH 7. Antimicrobial activity assays against Propionibacterium acnes were conducted to take advantage of the pH-sensitive properties of HECHA13. At pH 7, we found that HECHA13, which contained ILTG, inhibited the growth of P. acnes. Furthermore, HECHA13 was found to exhibit excellent permeability into the skin, which penetrated mostly via the hair follicle. These results indicate that this pH-sensitive hydrogel is effective as a transdermal delivery system for antimicrobial therapeutics, with potential applications in the treatment of acne. Copyright © 2015 Elsevier B.V. All rights reserved.

A hydrogel-actuated environmentally sensitive microvalve for active flow control

NARCIS (Netherlands)

Baldi, A.; Gu, Y. D.; Loftness, P. E.; Siegel, R. A.; Ziaie, B.

2003-01-01

This paper reports on the fabrication and test of a hydrogel-actuated microvalve that responds to changes in the concentration of specific chemical species in an external liquid environment. The microvalve consists of a thin hydrogel, sandwiched between a stiff porous membrane and a flexible

Biocompatibility of hyaluronic acid hydrogels prepared by porous hyaluronic acid microbeads

Science.gov (United States)

Kim, Jin-Tae; Lee, Deuk Yong; Kim, Tae-Hyung; Song, Yo-Seung; Cho, Nam-Ihn

2014-05-01

Hyaluronic acid hydrogels (HAHs) were synthesized by immersing HA microbeads crosslinked with divinyl sulfone in a phosphate buffered saline solution to evaluate the biocompatibility of the gels by means of cytotoxicity, genotoxicity ( in vitro chromosome aberration test, reverse mutation assay, and in vivo micronucleus test), skin sensitization, and intradermal reactivity. The HAHs induced no cytotoxicity or genotoxicity. In guinea pigs treated with grafts and prostheses, no animals died and there were no abnormal clinical signs. The sensitization scores were zero in all guinea pigs after 24 h and 48 h challenge, suggesting that the HAHs had no contact allergic sensitization in the guinea pig maximization test. No abnormal signs were found in New Zealand White rabbits during the 72 h observation period after the injection. There was no difference between the HAHs and negative control mean scores because skin reaction such as erythema or oedema was not observed after injection. Experimental results suggest that the HAHs would be suitable for soft tissue augmentation due to the absence of cytotoxicity, genotoxicity, skin sensitization, and intradermal reactivity.

Synthesis and Swelling Behavior of pH-Sensitive Semi-IPN Superabsorbent Hydrogels Based on Poly(acrylic acid Reinforced with Cellulose Nanocrystals

Directory of Open Access Journals (Sweden)

Lim Sze Lim

2017-11-01

Full Text Available pH-sensitive poly(acrylic acid (PAA hydrogel reinforced with cellulose nanocrystals (CNC was prepared. Acrylic acid (AA was subjected to chemical cross-linking using the cross-linking agent MBA (N,N-methylenebisacrylamide with CNC entrapped in the PAA matrix. The quantity of CNC was varied between 0, 5, 10, 15, 20, and 25 wt %. X-ray diffraction (XRD data showed an increase in crystallinity with the addition of CNC, while rheology tests demonstrated a significant increase in the storage modulus of the hydrogel with an increase in CNC content. It was found that the hydrogel reached maximum swelling at pH 7. The potential of the resulting hydrogels to act as drug carriers was then evaluated by means of the drug encapsulation efficiency test using theophylline as a model drug. It was observed that 15% CNC/PAA hydrogel showed the potential to be used as drug carrier system.

l-Arginine grafted alginate hydrogel beads: A novel pH-sensitive system for specific protein delivery

Directory of Open Access Journals (Sweden)

Mohamed S. Mohy Eldin

2015-05-01

Full Text Available Novel pH-sensitive hydrogels based on l-arginine grafted alginate (Arg-g-Alg hydrogel beads were synthesized and utilized as a new carrier for protein delivery (BSA in specific pH media. l-arginine was grafted onto the polysaccharide backbone of virgin alginate via amine functions. Evidences of grafting of alginate were extracted from FT-IR and thermal analysis, while the morphological structure of Arg-g-Alg hydrogel beads was investigated by SEM photographs. Factors affecting on the grafting process e.g. l-arginine concentration, reaction time, reaction temperature, reaction pH, and crosslinking conditions, have been studied. Whereas, grafting efficiency of each factor was evaluated. Grafting of alginate has improved both thermal and morphological properties of Arg-g-Alg hydrogel beads. The swelling behavior of Arg-g-Alg beads was determined as a function of pH and compared with virgin calcium alginate beads. The cumulative in vitro release profiles of BSA loaded beads were studied at different pHs for simulating the physiological environments of the gastrointestinal tract. The amount of BSA released from neat alginate beads at pH 2 was almost 15% after 5 h, while the Arg-g-Alg beads at the same conditions were clearly higher than 45%, then it increased to 90% at pH 7.2. Accordingly, grafting of alginate has improved its release profile behavior particularly in acidic media. The preliminary results clearly suggested that the Arg-g-Alg hydrogel may be a potential candidate for polymeric carrier for oral delivery of protein or drugs.

HLC/pullulan and pullulan hydrogels: their microstructure, engineering process and biocompatibility

Energy Technology Data Exchange (ETDEWEB)

Li, Xian [College of chemistry & materials science, Northwest University, Taibai North Road 229, Xi’an, Shaanxi 710069 (China); Shaanxi Key Laboratory of Degradable Biomedical Materials, Department of Chemical Engineering, Northwest University, Taibai North Road 229, Xi’an, Shaanxi 710069 (China); Xue, Wenjiao [Shannxi provincial institute of microbiology, Xi’ an 710043 (China); Liu, Yannan; Li, Weina [Shaanxi Key Laboratory of Degradable Biomedical Materials, Department of Chemical Engineering, Northwest University, Taibai North Road 229, Xi’an, Shaanxi 710069 (China); Fan, Daidi, E-mail: fandaidi@nwu.edu.cn [Shaanxi Key Laboratory of Degradable Biomedical Materials, Department of Chemical Engineering, Northwest University, Taibai North Road 229, Xi’an, Shaanxi 710069 (China); Zhu, Chenhui [Shaanxi Key Laboratory of Degradable Biomedical Materials, Department of Chemical Engineering, Northwest University, Taibai North Road 229, Xi’an, Shaanxi 710069 (China); Wang, Yaoyu, E-mail: wyaoyu@nwu.edu.cn [College of chemistry & materials science, Northwest University, Taibai North Road 229, Xi’an, Shaanxi 710069 (China)

2016-01-01

New locally injectable biomaterials that are suitable for use as soft tissue fillers are needed to address a significant unmet medical need. In this study, we used pullulan and human-like collagen (HLC) based hydrogels with various molecular weights (MWs) in combination therapy against tissue defects. Briefly, pullulan was crosslinked with NaIO{sub 4} to form a pullulan hydrogel and then may coupled with HLC using the reaction between the –NH{sub 2} end-group of HLC and the –CHO group present on the aldehyde pullulan to form the HLC/pullulan hydrogel, wherein the NaIO{sub 4} acted as the crosslinking and oxidizing agent. The good miscibility of pullulan and HLC in the hydrogels was confirmed via Fourier transform infrared spectroscopy, scanning electron microscopy, compression testing, enzyme degradation testing, cell adhesions, live/dead staining and subcutaneous filling assays. Here, pullulan hydrogels with various MWs were fabricated and physicochemically characterized. Limitations of the pullulan hydrogels included inflammation, poor mechanical strength, and degradation. By contrast, the properties of the HLC/pullulan hydrogels strongly enhanced. The efficacy of these hydrogels was evaluated both in vitro and in vivo. Our results indicate that HLC/pullulan hydrogels may have therapeutic value as efficient soft tissue fillers, with reduced inflammation, improved cell adhesion and delayed hydrogel degradation. - Graphical abstract: The HLC/pullulan hydrogels were prepared by dialysis, wet granulation and UV radiation after various MWs of pullulan and HLC were crosslinked with NaIO{sub 4}, and injected subcutaneously into Kunming mouse. The formation of HLC/pullulan hydrogels is due to the amide bond linkage with the amino group of HLC and the aldehyde groups in pullulan aqueous media after crosslinking by NaIO{sub 4}. HLC/pullulan hydrogels may have therapeutic value as efficient soft tissue fillers, with reduced inflammation, improved cell adhesion and

Surface plasmon optics for biosensors with advanced sensitivity and throughput

International Nuclear Information System (INIS)

Toma, M.

2012-01-01

Plasmonic biosensors represent a rapidly advancing technology which enables rapid and sensitive analysis of target analytes. This thesis focuses on novel metallic and polymer structures for plasmonic biosensors based on surface plasmon resonance (SPR) and surface plasmon-enhanced fluorescence (SPF). It comprises four projects addressing key challenges concerning the enhancement of sensitivity and throughput. In the project 1, an advanced optical platform is developed which relies on reference-compensated angular spectroscopy of hydrogel-guided waves. The developed optical setup provides superior refractive index resolution of 1.2×10 -7 RIU and offers an attractive platform for direct detection of small analytes which cannot be analyzed by regular SPR biosensors. The project 2 carries out theoretical study of SPR imaging with advanced lateral resolution by utilizing Bragg scattered surface plasmons (BSSPs) on sub-wavelength metallic gratings. The results reveal that the proposed concept provides better lateral resolution and fidelity of the images. This feature opens ways for high-throughput SPR biosensors with denser arrays of sensing spots. The project 3 investigates surface plasmon coupled-emission from fluorophores in the vicinity of plasmonic Bragg-gratings. The experimental results provide leads on advancing the collection efficiency of fluorescence light by controlling the directions of fluorescence emission. This functionality can directly improve the sensitivity of fluorescence-based assays. In the last project 4, a novel sensing scheme with actively tuneable plasmonic structures is developed by employing thermo-responsive hydrogel binding matrix. The hydrogel film simultaneously serves as a large capacity binding matrix and provides means for actuating of surface plasmons through reversible swelling and collapsing of the hydrogel. This characteristic is suitable for multiplexing of sensing channels in fluorescence-based biosensor scheme (author)

Evaluation of the chitosan/glycerol-β-phosphate disodium salt hydrogel application in peripheral nerve regeneration

International Nuclear Information System (INIS)

Zheng Lu; Zhang Xiufang; Gong Yandao; Ao Qiang; Han Hongyan

2010-01-01

Research efforts have been devoted to evaluating the application of the chitosan (CS)/glycerol-β-phosphate (GP) disodium salt hydrogel in peripheral nerve regeneration. The gelation time was determined to be 770 s using ultraviolet spectrophotometry. A standard 10 mm long rat sciatic nerve defect model was employed, followed by bridging the proximal and distal stumps with chitosan conduits injected with the Schwann cell-containing hydrogel. Injections of the blank hydrogel, Schwann cell suspension and culture medium were used as controls. Two months later, electrophysiological assessment and fluorogold retrograde tracing showed that compound muscle action potentials (CMAPs) and fluorogold-labeled neurons were only detected in the Schwann cell suspension group and culture medium group. The rats were then killed, and implanted conduits were removed for examination. There were no regenerated nerves found in groups injected with the blank hydrogel or Schwann cell-containing hydrogel, while the other two groups clearly displayed regenerated nerves across the gaps. In the subsequent histological assessment, immunohistochemistry, toluidine blue staining and transmission electron microscopy were performed to evaluate the regenerated nerves. The relative wet weight ratio, Masson trichrome staining and acetylcholinesterase staining were employed for the examination of gastrocnemius muscles in all four groups. The Schwann cell suspension group showed the best results for all these indexes; the culture medium group ranked second and the two hydrogel-injected groups showed the least optimal results. In conclusion, our data revealed that the implanted CS/GP hydrogel actually impeded nerve regeneration, which is inconsistent with former in vitro reports and general supposition. We believe that the application of the CS/GP hydrogel in nerve regeneration requires a further study before a satisfactory result is obtained. In addition, the present study also confirmed that Schwann

A chemo-electro-mechanical model for simulation of responsive deformation of glucose-sensitive hydrogels with the effect of enzyme catalysis

Science.gov (United States)

Li, Hua; Luo, Rongmo; Birgersson, Erik; Lam, Khin Yong

2009-02-01

A multi-effect-coupling glucose-stimulus (MECglu) model is developed and solved numerically for the swelling behavior of soft smart hydrogels responding to changes in the environmental glucose concentration. The model considers the effect of the glucose oxidation reaction catalyzed by enzymes including glucose oxidase and catalase. It is composed of the Nernst-Planck equation for the mobile species in the solvent, the Poisson equation for the electric potential, and a nonlinear mechanical equation for the large deformations of the hydrogel that arise due to the conversion of chemical energy to mechanical. Based on the theory of the chemo-electro-mechanical-coupled fields, the formulation of the fixed charge groups bound onto the cross-linked polymer network is associated with the change of the ambient solution pH. The MECglu model is validated by comparison between the steady-state computation and experimental equilibrium swelling curves, and good agreement is obtained. A parameter study is then conducted by steady-state simulations to ascertain the impact of various solvent parameters on the responsive swelling behavior of the hydrogel. One key parameter is the glucose concentration, which is varied within the range of practical physiological glucose concentrations from 0 to 16.5 mM (300 mg/ml) to support the design and optimization of an insulin delivery system based on a glucose-sensitive hydrogel with immobilized glucose oxidase and catalase. The influence of oxygen and glucose concentrations in the solvent is then further studied for the distributive profiles of reacting and diffusive species concentrations, the electric potential, the displacement, as well as the swelling ratio of the glucose-sensitive hydrogel.

Effect of liposomes on rheological and syringeability properties of hyaluronic acid hydrogels intended for local injection of drugs.

Science.gov (United States)

El Kechai, Naila; Bochot, Amélie; Huang, Nicolas; Nguyen, Yann; Ferrary, Evelyne; Agnely, Florence

2015-06-20

The aim of this work was to thoroughly study the effect of liposomes on the rheological and the syringeability properties of hyaluronic acid (HA) hydrogels intended for the local administration of drugs by injection. Whatever the characteristics of the liposomes added (neutral, positively or negatively charged, with a corona of polyethylene glycol chains, size), the viscosity and the elasticity of HA gels increased in a lipid concentration-dependent manner. Indeed, liposomes strengthened the network formed by HA chains due to their interactions with this polymer. The nature and the resulting effects of these interactions depended on liposome composition and concentration. The highest viscosity and elasticity were observed with liposomes covered by polyethylene glycol chains while neutral liposomes displayed the lowest effect. Despite their high viscosity at rest, all the formulations remained easily injectable through needles commonly used for local injections thanks to the shear-thinning behavior of HA gels. The present study demonstrates that rheological and syringeability tests are both necessary to elucidate the behavior of such systems during and post injection. In conclusion, HA liposomal gels appear to be a promising and versatile formulation platform for a wide range of applications in local drug delivery when an injection is required. Copyright © 2015 Elsevier B.V. All rights reserved.

Poly(vinyl alcohol)/poly(acrylic acid)/TiO2/graphene oxide nanocomposite hydrogels for pH-sensitive photocatalytic degradation of organic pollutants

International Nuclear Information System (INIS)

Moon, Young-E; Jung, Gowun; Yun, Jumi; Kim, Hyung-Il

2013-01-01

Graphical abstract: The photocatalytic removal of pollutants was improved by the two-step mechanism based on the adsorption of pollutants by hydrogel and the effective decomposition by combination of TiO 2 and graphene oxide. -- Highlights: • pH sensitive PVA/PAAc hydrogels were prepared by radical polymerization and condensation reaction. • PVA/PAAc/TiO 2 /graphene oxide nanocomposite hydrogels were used for treatment of basic waste water. • Photocatalytic acitivity of TiO 2 was improved by incorporation of graphene oxide. • Photocatalytic decomposition by nanocomposite hydrogel was improved by increasing pH. -- Abstract: Poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were prepared using radical polymerization and condensation reaction for the photocatalytic treatment of waste water. Graphene oxide was used as an additive to improve the photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 nanocomposite hydrogels. Both TiO 2 and graphene oxide were immobilized in poly(vinyl alcohol)/poly(acrylic acid) hydrogel matrix for an easier recovery after the waste water treatment. The photocatalytic activity of poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels was evaluated on the base of the degradation of pollutants by using UV spectrometer. The improved removal of pollutants was due to the two-step mechanism based on the adsorption of pollutants by nanocomposite hydrogel and the effective decomposition of pollutants by TiO 2 and graphene oxide. The highest swelling of nanocomposite hydrogel was observed at pH 10 indicating that poly(vinyl alcohol)/poly(acrylic acid)/TiO 2 /graphene oxide nanocomposite hydrogels were suitable as a promising system for the treatment of basic waste water

Hydrogel delivery of lysostaphin eliminates orthopedic implant infection by Staphylococcus aureus and supports fracture healing.

Science.gov (United States)

Johnson, Christopher T; Wroe, James A; Agarwal, Rachit; Martin, Karen E; Guldberg, Robert E; Donlan, Rodney M; Westblade, Lars F; García, Andrés J

2018-05-29

Orthopedic implant infections are a significant clinical problem, with current therapies limited to surgical debridement and systemic antibiotic regimens. Lysostaphin is a bacteriolytic enzyme with high antistaphylococcal activity. We engineered a lysostaphin-delivering injectable PEG hydrogel to treat Staphylococcus aureus infections in bone fractures. The injectable hydrogel formulation adheres to exposed tissue and fracture surfaces, ensuring efficient, local delivery of lysostaphin. Lysostaphin encapsulation within this synthetic hydrogel maintained enzyme stability and activity. Lysostaphin-delivering hydrogels exhibited enhanced antibiofilm activity compared with soluble lysostaphin. Lysostaphin-delivering hydrogels eradicated S. aureus infection and outperformed prophylactic antibiotic and soluble lysostaphin therapy in a murine model of femur fracture. Analysis of the local inflammatory response to infections treated with lysostaphin-delivering hydrogels revealed indistinguishable differences in cytokine secretion profiles compared with uninfected fractures, demonstrating clearance of bacteria and associated inflammation. Importantly, infected fractures treated with lysostaphin-delivering hydrogels fully healed by 5 wk with bone formation and mechanical properties equivalent to those of uninfected fractures, whereas fractures treated without the hydrogel carrier were equivalent to untreated infections. Finally, lysostaphin-delivering hydrogels eliminate methicillin-resistant S. aureus infections, supporting this therapy as an alternative to antibiotics. These results indicate that lysostaphin-delivering hydrogels effectively eliminate orthopedic S. aureus infections while simultaneously supporting fracture repair. Copyright © 2018 the Author(s). Published by PNAS.

Structure formation in pH-sensitive hydrogels composed of sodium caseinate and N,O-carboxymethyl chitosan.

Science.gov (United States)

Wei, Yanxia; Xie, Rui; Lin, Yanbin; Xu, Yunfei; Wang, Fengxia; Liang, Wanfu; Zhang, Ji

2016-08-01

The pH-sensitive hydrogels composed of sodium caseinate (SC) and N,O-carboxymethyl chitosan (NOCC) were prepared and a new method to characterize the gelation process was presented in this work. Reological tests suggested that RSC/NOCC=3/7 (the weight ratio of SC and NOCC) was the best ratio of hydrogel. The well-developed three-dimensional network structures in the hydrogel were confirmed by AFM. Two structural parameters, tIS and tCS, denoted as the initial and critical structure formation time, respectively, were used to provide an exact determination of the start of structure formation and description of gelation process. The gelation process strongly depended on temperature changes, a high temperature resulted in an early start of gelation. The non-kinetic model suggested the higher activation energy in the higher temperatures was disadvantageous to structure formation, and vice versa. Due to the smart gel reported here was very stable at room temperature, we believed that the gel is required for applications in drug delivery or could be exploited in the development of potential application as molecular switches in the future. Copyright © 2016 Elsevier B.V. All rights reserved.

EUV lithographic radiation grafting of thermo-responsive hydrogel nanostructures

International Nuclear Information System (INIS)

Farquet, Patrick; Padeste, Celestino; Solak, Harun H.; Guersel, Selmiye Alkan; Scherer, Guenther G.; Wokaun, Alexander

2007-01-01

Nanostructures of the thermoresponsive poly(N-isopropyl acrylamide) (PNIPAAm) and of PNIPAAm-block-poly(acrylic acid) copolymers were produced on poly(tetrafluoroethylene-co-ethyelene) (ETFE) films using extreme ultraviolet (EUV) lithographic exposure with subsequent graft-polymerization. The phase transition of PNIPAAm nanostructures at the low critical solution temperature (LCST) at 32 deg. C was imaged by atomic force microscopy (AFM) phase contrast measurements in pure water. Results show a higher phase contrast for samples measured below the LCST temperature than for samples above the LCST, proving that the soft PNIPAAm hydrogel transforms into a much more compact conformation above the LCST. EUV lithographic exposures were combined with the reversible addition-fragment chain transfer (RAFT)-mediated polymerization using cyanoisopropyl dithiobenzoate (CPDB) as chain transfer agent to synthesize PNIPAAm block-copolymer nanostructures

Radiation synthesis and characterization of polyacrylic acid hydrogels

International Nuclear Information System (INIS)

Yang Mingcheng; Song Hongyan; Zhu Chengshen; He Suqin

2007-01-01

The pH-sensitive polyacrylic acid (PAA) hydrogels were synthesized by gamma-ray irradiation at an ambient temperature. The influences of dose, monomer concentration, cross-linking agent content, pH, and ionic strength on the swelling ratio (SR) of the PAA hydrogels were investigated in detail. The results show that the SR of the hydrogel decreases with an increase in the dose, monomer concentration, and cross-linking agent content. In alkaline solution, the SR of the hydrogels is much higher than that in acid solution. Also, the ionic strength can influence the SR of the hydrogels. The more the concentration, the lower the SR. (authors)

Polyvinyl alcohol hydrogels for iontohporesis

Science.gov (United States)

Bera, Prasanta; Alam, Asif Ali; Arora, Neha; Tibarewala, Dewaki Nandan; Basak, Piyali

2013-06-01

Transdermal therapeutic systems propound controlled release of active ingredients through the skin into the systemic circulation in a predictive manner. Drugs administered through these systems escape first-pass metabolism and maintain a steady state scenario similar to a continuous intravenous infusion for up to several days. The iontophoresis deal with the systemic delivery of the bioactive agents (drug) by applying an electric current. It is basically an injection without the needle. The iontophoretic system requires a gel-based matrix to accommodate the bioactive agent. Hydrogels have been used by many investigators in controlled-release drug delivery systems because of their good tissue compatibility and easy manipulation of swelling level and, thereby, solute permeability. In this work we have prepared polyvinyl alcohol (PVA) hydrogel. We have cross linked polyvinyl alcohol chemically with Glutaraldehyde with different wt%. FTIR study reveals the chemical changes during cross linking. Swelling in water, is done to have an idea about drug loading and drug release from the membrane. After drug loading to the hydrogels, we have studied the drug release property of the hydrogels using salicylic acid as a model drug.

Hydrogel-based sensor for CO2 measurements

NARCIS (Netherlands)

Herber, S.; Olthuis, Wouter; Bergveld, Piet; van den Berg, Albert

2004-01-01

A hydrogel-based sensor is presented for CO2 measurements. The sensor consists of a pressure sensor and porous silicon cover. A pH-sensitive hydrogel is confined between the two parts. Furthermore the porous cover contains a bicarbonate solution and a gaspermeable membrane. CO2 reacts with the

Nanocomposite Hydrogels: 3D Polymer-Nanoparticle Synergies for On-Demand Drug Delivery.

Science.gov (United States)

Merino, Sonia; Martín, Cristina; Kostarelos, Kostas; Prato, Maurizio; Vázquez, Ester

2015-05-26

Considerable progress in the synthesis and technology of hydrogels makes these materials attractive structures for designing controlled-release drug delivery systems. In particular, this review highlights the latest advances in nanocomposite hydrogels as drug delivery vehicles. The inclusion/incorporation of nanoparticles in three-dimensional polymeric structures is an innovative means for obtaining multicomponent systems with diverse functionality within a hybrid hydrogel network. Nanoparticle-hydrogel combinations add synergistic benefits to the new 3D structures. Nanogels as carriers for cancer therapy and injectable gels with improved self-healing properties have also been described as new nanocomposite systems.

The effect of platelet lysate supplementation of a dextran-based hydrogel on cartilage formation

NARCIS (Netherlands)

Moreira Teixeira, Liliana; Leijten, Jeroen Christianus Hermanus; Wennink, J.W.H.; Ganguly, Anindita; Feijen, Jan; van Blitterswijk, Clemens; Dijkstra, Pieter J.; Karperien, Hermanus Bernardus Johannes

2012-01-01

In situ gelating dextran-tyramine (Dex-TA) injectable hydrogels have previously shown promising features for cartilage repair. Yet, despite suitable mechanical properties, this system lacks intrinsic biological signals. In contrast, platelet lysate-derived hydrogels are rich in growth factors and

Sustained release of intravitreal flurbiprofen from a novel drug-in-liposome-in-hydrogel formulation.

Science.gov (United States)

Pachis, K; Blazaki, S; Tzatzarakis, M; Klepetsanis, P; Naoumidi, E; Tsilimbaris, M; Antimisiaris, S G

2017-11-15

A novel Flurbiprofen (FLB)-in-liposome-in-hydrogel formulation was developed, as a method to sustain the release and increase the ocular bioavailability of FLB following intravitreal injection. For this, FLB loading into liposomes was optimized and liposomes were entrapped in thermosensitive hydrogels consisted of Pluronic F-127 (P). FLB solution, liposomes, and FLB dissolved in hydrogel were also used as control formulations. Actively loaded liposomes were found to be optimal for high FLB loading and small size, while in vitro studies revealed that P concentration of 18% (w/v) was best to retain the integrity of the hydrogel-dispersed liposome, compared to a 20% concentration. The in vitro release of FLB was significantly sustained when FLB-liposomes were dispersed in the hydrogel compared to hydrogel dissolved FLB, as well as the other control formulations. In vivo studies were carried out in pigmented rabbits which were injected through a 27G needle with 1mg/mL FLB in the different formulation-types. Ophthalmic examinations after intravitreal injection of all FLB formulations, revealed no evidence of inflammation, hemorrhage, uveitis or endophthalmitis. Pharmacokinetic analysis results confirm that the hybrid drug delivery system increases the bioavailability (by 1.9 times compared to solution), and extends the presence of the drug in the vitreous cavity, while liposome and hydrogel formulations demonstrate intermediate performance. Furthermore the hybrid system increases MRT of FLB in aqueous humor and retina/choroid tissues, compared to all the control formulations. Currently the potential therapeutic advances of FLB sustained release formulations for IVT administration are being evaluated. Copyright © 2017 Elsevier B.V. All rights reserved.

Hydrogel based QCM aptasensor for detection of avian influenza virus.

Science.gov (United States)

Wang, Ronghui; Li, Yanbin

2013-04-15

The objective of this study was to develop a quartz crystal microbalance (QCM) aptasensor based on ssDNA crosslinked polymeric hydrogel for rapid, sensitive and specific detection of avian influenza virus (AIV) H5N1. A selected aptamer with high affinity and specificity against AIV H5N1 surface protein was used, and hybridization between the aptamer and ssDNA formed the crosslinker in the polymer hydrogel. The aptamer hydrogel was immobilized on the gold surface of QCM sensor using a self-assembled monolayer method. The hydrogel remained in the state of shrink if no H5N1 virus was present in the sample because of the crosslinking between the aptamer and ssDNA in the polymer network. When it exposed to target virus, the binding reaction between the aptamer and H5N1 virus caused the dissolution of the linkage between the aptamer and ssDNA, resulting in the abrupt swelling of the hydrogel. The swollen hydrogel was monitored by the QCM sensor in terms of decreased frequency. Three polymeric hydrogels with different ratio (100:1 hydrogel I, 10:1 hydrogel II, 1:1 hydrogel III) of acrylamide and the aptamer monomer were synthesized, respectively, and then were used as the QCM sensor coating material. The results showed that the developed hydrogel QCM aptasensor was capable of detecting target H5N1 virus, and among the three developed aptamer hydrogels, hydrogel III coated QCM aptasensor achieved the highest sensitivity with the detection limit of 0.0128 HAU (HA unit). The total detection time from sampling to detection was only 30 min. In comparison with the anti-H5 antibody coated QCM immunosensor, the hydrogel QCM aptasensor lowered the detection limit and reduced the detection time. Copyright © 2012 Elsevier B.V. All rights reserved.

A pH- and temperature-responsive bioresorbable injectable hydrogel based on polypeptide block copolymers for the sustained delivery of proteins in vivo.

Science.gov (United States)

Turabee, Md Hasan; Thambi, Thavasyappan; Duong, Huu Thuy Trang; Jeong, Ji Hoon; Lee, Doo Sung

2018-02-27

Sustained delivery of protein therapeutics is limited owing to the fragile nature of proteins. Despite its great potential, delivery of proteins without any loss of bioactivity remains a challenge in the use of protein therapeutics in the clinic. To surmount this shortcoming, we report a pH- and temperature-responsive in situ-forming injectable hydrogel based on comb-type polypeptide block copolymers for the controlled delivery of proteins. Polypeptide block copolymers, composed of hydrophilic polyethylene glycol (PEG), temperature-responsive poly(γ-benzyl-l-glutamate) (PBLG), and pH-responsive oligo(sulfamethazine) (OSM), exhibit pH- and temperature-induced sol-to-gel transition behavior in aqueous solutions. Polypeptide block copolymers were synthesized by combining N-carboxyanhydride-based ring-opening polymerization and post-functionalization of the chain-end using N-hydroxy succinimide ester activated OSM. The physical properties of polypeptide-based hydrogels were tuned by varying the composition of temperature- and pH-responsive PBLG and OSM in block copolymers. Polypeptide block copolymers were non-toxic to human embryonic kidney cells at high concentrations (2000 μg mL -1 ). Subcutaneous administration of polypeptide block copolymer sols formed viscoelastic gel instantly at the back of Sprague-Dawley (SD) rats. The in vivo gels exhibited sustained degradation and were found to be bioresorbable in 6 weeks without any noticeable inflammation at the injection site. Anionic characteristics of hydrogels allow efficient loading of a cationic model protein, lysozyme, through electrostatic interaction. Lysozyme-loaded polypeptide block copolymer sols readily formed a viscoelastic gel in vivo and sustained lysozyme release for at least a week. Overall, the results demonstrate an elegant approach to control the release of certain charged proteins and open a myriad of therapeutic possibilities in protein therapeutics.

Analysis of responsive characteristics of ionic-strength-sensitive hydrogel with consideration of effect of equilibrium constant by a chemo-electro-mechanical model.

Science.gov (United States)

Li, Hua; Lai, Fukun; Luo, Rongmo

2009-11-17

A multiphysics model is presented in this paper for analysis of the influence of various equilibrium constants on the smart hydrogel responsive to the ionic strength of environmental solution, and termed the multieffect-coupling ionic-strength stimulus (MECis) model. The model is characterized by a set of partial differential governing equations by consideration of the mass and momentum conservations of the system and coupled chemical, electrical, and mechanical multienergy domains. The Nernst-Planck equations are derived by the mass conservation of the ionic species in both the interstitial fluid of the hydrogel and the surrounding solution. The binding reaction between the fixed charge groups of the hydrogel and the mobile ions in the solution is described by the fixed charge equation, which is based on the Langmuir monolayer theory. As an important effect for the binding reaction, the equilibrium constant is incorporated into the fixed charge equation. The kinetics of the hydrogel swelling/deswelling is illustrated by the mechanical equation, based on the law of momentum conservation for the solid polymeric networks matrix within the hydrogel. The MECis model is examined by comparison of the numerical simulations and experiments from open literature. The analysis of the influence of different equilibrium constants on the responsive characteristics of the ionic-strength-sensitive hydrogel is carried out with detailed discussion.

A large deformation viscoelastic model for double-network hydrogels

Science.gov (United States)

Mao, Yunwei; Lin, Shaoting; Zhao, Xuanhe; Anand, Lallit

2017-03-01

We present a large deformation viscoelasticity model for recently synthesized double network hydrogels which consist of a covalently-crosslinked polyacrylamide network with long chains, and an ionically-crosslinked alginate network with short chains. Such double-network gels are highly stretchable and at the same time tough, because when stretched the crosslinks in the ionically-crosslinked alginate network rupture which results in distributed internal microdamage which dissipates a substantial amount of energy, while the configurational entropy of the covalently-crosslinked polyacrylamide network allows the gel to return to its original configuration after deformation. In addition to the large hysteresis during loading and unloading, these double network hydrogels also exhibit a substantial rate-sensitive response during loading, but exhibit almost no rate-sensitivity during unloading. These features of large hysteresis and asymmetric rate-sensitivity are quite different from the response of conventional hydrogels. We limit our attention to modeling the complex viscoelastic response of such hydrogels under isothermal conditions. Our model is restricted in the sense that we have limited our attention to conditions under which one might neglect any diffusion of the water in the hydrogel - as might occur when the gel has a uniform initial value of the concentration of water, and the mobility of the water molecules in the gel is low relative to the time scale of the mechanical deformation. We also do not attempt to model the final fracture of such double-network hydrogels.

Biodegradable Cellulose-based Hydrogels: Design and Applications

Science.gov (United States)

Sannino, Alessandro; Demitri, Christian; Madaghiele, Marta

2009-01-01

Hydrogels are macromolecular networks able to absorb and release water solutions in a reversible manner, in response to specific environmental stimuli. Such stimuli-sensitive behaviour makes hydrogels appealing for the design of ‘smart’ devices, applicable in a variety of technological fields. In particular, in cases where either ecological or biocompatibility issues are concerned, the biodegradability of the hydrogel network, together with the control of the degradation rate, may provide additional value to the developed device. This review surveys the design and the applications of cellulose-based hydrogels, which are extensively investigated due to the large availability of cellulose in nature, the intrinsic degradability of cellulose and the smart behaviour displayed by some cellulose derivatives.

Biodegradable Cellulose-based Hydrogels: Design and Applications

Directory of Open Access Journals (Sweden)

Marta Madaghiele

2009-04-01

Full Text Available Hydrogels are macromolecular networks able to absorb and release water solutions in a reversible manner, in response to specific environmental stimuli. Such stimuli-sensitive behaviour makes hydrogels appealing for the design of ‘smart’ devices, applicable in a variety of technological fields. In particular, in cases where either ecological or biocompatibility issues are concerned, the biodegradability of the hydrogel network, together with the control of the degradation rate, may provide additional value to the developed device. This review surveys the design and the applications of cellulose-based hydrogels, which are extensively investigated due to the large availability of cellulose in nature, the intrinsic degradability of cellulose and the smart behaviour displayed by some cellulose derivatives.

Extracellular matrix hydrogels from decellularized tissues: Structure and function.

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Saldin, Lindsey T; Cramer, Madeline C; Velankar, Sachin S; White, Lisa J; Badylak, Stephen F

2017-02-01

Extracellular matrix (ECM) bioscaffolds prepared from decellularized tissues have been used to facilitate constructive and functional tissue remodeling in a variety of clinical applications. The discovery that these ECM materials could be solubilized and subsequently manipulated to form hydrogels expanded their potential in vitro and in vivo utility; i.e. as culture substrates comparable to collagen or Matrigel, and as injectable materials that fill irregularly-shaped defects. The mechanisms by which ECM hydrogels direct cell behavior and influence remodeling outcomes are only partially understood, but likely include structural and biological signals retained from the native source tissue. The present review describes the utility, formation, and physical and biological characterization of ECM hydrogels. Two examples of clinical application are presented to demonstrate in vivo utility of ECM hydrogels in different organ systems. Finally, new research directions and clinical translation of ECM hydrogels are discussed. More than 70 papers have been published on extracellular matrix (ECM) hydrogels created from source tissue in almost every organ system. The present manuscript represents a review of ECM hydrogels and attempts to identify structure-function relationships that influence the tissue remodeling outcomes and gaps in the understanding thereof. There is a Phase 1 clinical trial now in progress for an ECM hydrogel. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Preparation of thermo-sensitive slow releasing material and its application in low tar tobacco

Directory of Open Access Journals (Sweden)

Tian Zhong

2017-04-01

Full Text Available To solve some sensory defects such as fragrance deficiency,strong dry sense,poor satisfaction in the development of ultra-low tar tobacco products,we prepared a new thermo sensitive slow releasing composite material with tobacco aroma.The characterization results showed that the as-prepared thermosensitive particles have better aroma enhancing and slow releasing effects.Also,the aroma components of the tip stick containing thermosensitive particles were detected and its sensory quality was evaluated.The results showed that composite tip stick could enhance the aroma and improve the sensory quality of the cigarettes.

Hybrid nanocomposites based on electroactive hydrogels and cellulose nanocrystals for high-sensitivity electro-mechanical underwater actuation

Science.gov (United States)

Santaniello, Tommaso; Migliorini, Lorenzo; Locatelli, Erica; Monaco, Ilaria; Yan, Yunsong; Lenardi, Cristina; Comes Franchini, Mauro; Milani, Paolo

2017-08-01

We report the synthesis, fabrication and characterization of a hybrid hydrogel/cellulose nanocomposite, which exhibits high-performance electro-mechanical underwater actuation and high sensitivity in response to electrical stimuli below the standard potential of water electrolysis. The macromolecular structure of the material is constituted by an electroactive hydrogel, obtained through a photo-polymerization reaction with the use of three vinylic co-monomers: Na-4-vinylbenzenesulfonate, 2-hydroxyethylmethacrylate, and acrylonitrile. Different amounts (from 0.1% to 1.4% w/w) of biodegradable cellulose nanocrystals (CNCs) with sulfonate surface groups, obtained through the acidic hydrolysis of sulphite pulp lapsheets, are physically incorporated into the gel matrix during the synthesis step. Freestanding thin films of the nanocomposites are molded, and their swelling, mechanical and responsive properties are fully characterized. We observed that the embedding of the CNCs enhanced both the material Young’s modulus and its sensitivity to the applied electric field in the sub-volt regime (down to 5 mV cm-1). A demonstrator integrating multiple actuators that cooperatively bend together, mimicking the motion of an electro-valve, is also prototyped and tested. The presented nanocomposite is suitable for the development of soft smart components for bio-robotic applications and cells-based and bio-hybrid fluidic devices fabrication.

Photothermal-modulated drug delivery and magnetic relaxation based on collagen/poly(γ-glutamic acid hydrogel

Directory of Open Access Journals (Sweden)

Cho SH

2017-03-01

Full Text Available Sun-Hee Cho,1,* Ahreum Kim,1,* Woojung Shin,2 Min Beom Heo,1 Hyun Jong Noh,1 Kwan Soo Hong,3,4 Jee-Hyun Cho,3,4 Yong Taik Lim1,2 1SKKU Advanced Institute of Nanotechnology (SAINT, 2School of Chemical Engineering, Sungkyunkwan University, Suwon, 3Bioimaging Research Team, Korea Basic Science Institute, Cheongju, 4Immunotherapy Convergence Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Republic of Korea *These authors contributed equally to this work Abstract: Injectable and stimuli-responsive hydrogels have attracted attention in molecular imaging and drug delivery because encapsulated diagnostic or therapeutic components in the hydrogel can be used to image or change the microenvironment of the injection site by controlling various stimuli such as enzymes, temperature, pH, and photonic energy. In this study, we developed a novel injectable and photoresponsive composite hydrogel composed of anticancer drugs, imaging contrast agents, bio-derived collagen, and multifaceted anionic polypeptide, poly (γ-glutamic acid (γ-PGA. By the introduction of γ-PGA, the intrinsic temperature-dependent phase transition behavior of collagen was modified to a low viscous sol state at room temperature and nonflowing gel state around body temperature. The modified temperature-dependent phase transition behavior of collagen/γ-PGA hydrogels was also evaluated after loading of near-infrared (NIR fluorophore, indocyanine green (ICG, which could transform absorbed NIR photonic energy into thermal energy. By taking advantage of the abundant carboxylate groups in γ-PGA, cationic-charged doxorubicin (Dox and hydrophobic MnFe2O4 magnetic nanoparticles were also incorporated successfully into the collagen/γ-PGA hydrogels. By illumination of NIR light on the collagen/γ-PGA/Dox/ICG/MnFe2O4 hydrogels, the release kinetics of Dox and magnetic relaxation of MnFe2O4 nanoparticles could be modulated. The experimental results suggest that

Facile synthesis of degradable and electrically conductive polysaccharide hydrogels.

Science.gov (United States)

Guo, Baolin; Finne-Wistrand, Anna; Albertsson, Ann-Christine

2011-07-11

Degradable and electrically conductive polysaccharide hydrogels (DECPHs) have been synthesized by functionalizing polysaccharide with conductive aniline oligomers. DECPHs based on chitosan (CS), aniline tetramer (AT), and glutaraldehyde were obtained by a facile one-pot reaction by using the amine group of CS and AT under mild conditions, which avoids the multistep reactions and tedious purification involved in the synthesis of degradable conductive hydrogels in our previous work. Interestingly, these one-pot hydrogels possess good film-forming properties, electrical conductivity, and a pH-sensitive swelling behavior. The chemical structure and morphology before and after swelling of the hydrogels were verified by FT-IR, NMR, and SEM. The conductivity of the hydrogels was tuned by adjusting the content of AT. The swelling ratio of the hydrogels was altered by the content of tetraaniline and cross-linker. The hydrogels underwent slow degradation in a buffer solution. The hydrogels obtained by this facile approach provide new possibilities in biomedical applications, for example, biodegradable conductive hydrogels, films, and scaffolds for cardiovascular tissue engineering and controlled drug delivery.

Cartilaginous extracellular matrix-modified chitosan hydrogels for cartilage tissue engineering.

Science.gov (United States)

Choi, Bogyu; Kim, Soyon; Lin, Brian; Wu, Benjamin M; Lee, Min

2014-11-26

Cartilaginous extracellular matrix (ECM) components such as type-II collagen (Col II) and chondroitin sulfate (CS) play a crucial role in chondrogenesis. However, direct clinical use of natural Col II or CS as scaffolds for cartilage tissue engineering is limited by their instability and rapid enzymatic degradation. Here, we investigate the incorporation of Col II and CS into injectable chitosan hydrogels designed to gel upon initiation by exposure to visible blue light (VBL) in the presence of riboflavin. Unmodified chitosan hydrogel supported proliferation and deposition of cartilaginous ECM by encapsulated chondrocytes and mesenchymal stem cells. The incorporation of native Col II or CS into chitosan hydrogels further increased chondrogenesis. The incorporation of Col II, in particular, was found to be responsible for the enhanced cellular condensation and chondrogenesis observed in modified hydrogels. This was mediated by integrin α10 binding to Col II, increasing cell-matrix adhesion. These findings demonstrate the potential of cartilage ECM-modified chitosan hydrogels as biomaterials to promote cartilage regeneration.

Construction and characterization of a pure protein hydrogel for drug delivery application.

Science.gov (United States)

Xu, Xu; Xu, ZhaoKang; Yang, XiaoFeng; He, YanHao; Lin, Rong

2017-02-01

Injectable hydrogels have a variety of applications, including regenerative medicine, tissue engineering and controlled drug delivery. In this paper, we reported on a pure protein hydrogel based on tetrameric recombinant proteins for the potential drug delivery application. This protein hydrogel was formed instantly by simply mixing two recombinant proteins (ULD-TIP1 and ULD-GGGWRESAI) through the specific protein-peptide interaction. The protein hydrogel was characterized by rheology and scanning electron microscopy (SEM). In vitro cytotoxicity test indicated that the developed protein hydrogel had no apparent cytotoxicity against L-929 cells and HCEC cells after 48h incubation. The formed protein hydrogels was gradually degraded after incubation in phosphate buffered solution (PBS, pH=7.4) for a period of 144h study, as indicated by in vitro degradation test. Encapsulation of model drug (sodium diclofenac; DIC) were achieved by simple mixing of drugs with hydrogelator and the entrapped drugs was almost completely released from hydrogels within 24h via a diffusion manner. As a conclusion, the simple and mild preparation procedure and good biocompatibility of protein hydrogel would render its good promising candidate for drug delivery applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Physico-chemical study of new functionalized surfactants having thermo sensitive de-mixing behaviour: use in extraction of uranyl nitrate

International Nuclear Information System (INIS)

Prevost, S.

2006-04-01

New thermo-sensitive functionalized surfactants with metal-chelating properties have been developed and their physical-chemistry studied. They associate a polyethoxylated nonionic surfactant (CiEj) block and a amino-acid residue as a chelating group. Functionalization preserves both properties of the thermo-sensitive surfactant moiety and the chelating group, a diamide closed to uranyl ionophore.The complexing group participates to the polar head group of the surfactant, increasing the area per molecule. As a result, functionalized surfactants form spherical micelles when diluted in water, and the concentrated part of their phase diagrams exhibits structures having higher curvatures than the nonionic precursor CiEj. The structure of the uranyl - diamide complex has been elucidated by NMR and ESI-MS and is of the type UO 2 (NO 3 ) 2 .L; the associated complexation constant, which is very low, has been evaluated by 1 H NMR.A nitrate salt, LiNO 3 , is added at high concentration to improve complexation. The effect of this salt has been analyzed, and was found to be rather similar to the effect on classical CiEj. When uranyl nitrate complexation occurs, the cloud point decreases dramatically, together with the reduction of the area per head group at micelle/solution interface. This effect can be minimized by using a nonionic precursor having a larger polar head group. The functionalized surfactants have been tested in the cloud point extraction of uranyl nitrate, and have proved their efficiency. Those results demonstrate the viability of the functionalized surfactants design, with a covalent link between a thermo-sensitive surfactant block and a chelating group. (author)

Structural and biological properties of thermosensitive chitosan-graphene hybrid hydrogels for sustained drug delivery applications.

Science.gov (United States)

Saeednia, Leyla; Yao, Li; Berndt, Marcus; Cluff, Kim; Asmatulu, Ramazan

2017-09-01

Chitosan has the ability to make injectable thermosensitive hydrogels which has been highly investigated for drug delivery applications. The addition of nanoparticles is one way to increase the mechanical strength of thermosensitive chitosan hydrogel and subsequently and control the burst release of drug. Graphene nanoparticles have shown unique mechanical, optical and electrical properties which can be exploited for biomedical applications, especially in drug delivery. This study, have focused on the mechanical properties of a thermosensitive and injectable hybrid chitosan hydrogel incorporated with graphene nanoparticles. Scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and X-ray diffraction (XRD) have been used for morphological and chemical characterization of graphene infused chitosan hydrogels. The cell viability and cytotoxicity of graphene-contained hydrogels were analyzed using the alamarBlue ® technique. In-vitro methotrexate (MTX) release was investigated from MTX-loaded hybrid hydrogels as well. As a last step, to evaluate their efficiency as a cancer treatment delivery system, an in vitro anti-tumor test was also carried out using MCF-7 breast cancer cell lines. Results confirmed that a thermosensitive chitosan-graphene hybrid hydrogel can be used as a potential breast cancer therapy system for controlled delivery of methotrexate. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2381-2390, 2017. © 2017 Wiley Periodicals, Inc.

Bioprinting Organotypic Hydrogels with Improved Mesenchymal Stem Cell Remodeling and Mineralization Properties for Bone Tissue Engineering.

Science.gov (United States)

Duarte Campos, Daniela Filipa; Blaeser, Andreas; Buellesbach, Kate; Sen, Kshama Shree; Xun, Weiwei; Tillmann, Walter; Fischer, Horst

2016-06-01

3D-manufactured hydrogels with precise contours and biological adhesion motifs are interesting candidates in the regenerative medicine field for the culture and differentiation of human bone-marrow-derived mesenchymal stem cells (MSCs). 3D-bioprinting is a powerful technique to approach one step closer the native organization of cells. This study investigates the effect of the incorporation of collagen type I in 3D-bioprinted polysaccharide-based hydrogels to the modulation of cell morphology, osteogenic remodeling potential, and mineralization. By combining thermo-responsive agarose hydrogels with collagen type I, the mechanical stiffness and printing contours of printed constructs can be improved compared to pure collagen hydrogels which are typically used as standard materials for MSC osteogenic differentiation. The results presented here show that MSC not only survive the 3D-bioprinting process but also maintain the mesenchymal phenotype, as proved by live/dead staining and immunocytochemistry (vimentin positive, CD34 negative). Increased solids concentrations of collagen in the hydrogel blend induce changes in cell morphology, namely, by enhancing cell spreading, that ultimately contribute to enhanced and directed MSC osteogenic differentiation. 3D-bioprinted agarose-collagen hydrogels with high-collagen ratio are therefore feasible for MSC osteogenic differentiation, contrarily to low-collagen blends, as proved by two-photon microscopy, Alizarin Red staining, and real-time polymerase chain reaction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Miniaturized Carbon Dioxide Gas Sensor Based on Sensing of pH-Sensitive Hydrogel Swelling with a Pressure Sensor

NARCIS (Netherlands)

Herber, S.; Bomer, Johan G.; Olthuis, Wouter; Bergveld, Piet; van den Berg, Albert

2005-01-01

A measurement concept has been realized for the detection of carbon dioxide, where the CO2 induced pressure generation by an enclosed pH-sensitive hydrogel is measured with a micro pressure sensor. The application of the sensor is the quantification of the partial pressure of CO2 (Pco2) in the

Biomimetics of the extracellular matrix: an integrated three-dimensional fiber-hydrogel composite for cartilage tissue engineering

NARCIS (Netherlands)

Coburn, J.; Gibson, M.; Bandalini, P.A.; Laird, C.; Mao, H.Q.; Moroni, Lorenzo; Seliktar, D.; Elisseeff, J.H.

2011-01-01

The native extracellular matrix (ECM) consists of an integrated fibrous protein network and proteoglycan-based ground (hydrogel) substance. We designed a novel electrospinning technique to engineer a three dimensional fiber-hydrogel composite that mimics the native ECM structure, is injectable, and

Human Adipose Tissue Derived Extracellular Matrix and Methylcellulose Hydrogels Augments and Regenerates the Paralyzed Vocal Fold.

Science.gov (United States)

Kim, Dong Wook; Kim, Eun Ji; Kim, Eun Na; Sung, Myung Whun; Kwon, Tack-Kyun; Cho, Yong Woo; Kwon, Seong Keun

2016-01-01

Vocal fold paralysis results from various etiologies and can induce voice changes, swallowing complications, and issues with aspiration. Vocal fold paralysis is typically managed using injection laryngoplasty with fat or synthetic polymers. Injection with autologous fat has shown excellent biocompatibility. However, it has several disadvantages such as unpredictable resorption rate, morbidities associated with liposuction procedure which has to be done in operating room under general anesthesia. Human adipose-derived extracellular matrix (ECM) grafts have been reported to form new adipose tissue and have greater biostability than autologous fat graft. Here, we present an injectable hydrogel that is constructed from adipose tissue derived soluble extracellular matrix (sECM) and methylcellulose (MC) for use in vocal fold augmentation. Human sECM derived from adipose tissue was extracted using two major steps-ECM was isolated from human adipose tissue and was subsequently solubilized. Injectable sECM/MC hydrogels were prepared by blending of sECM and MC. Sustained vocal fold augmentation and symmetric vocal fold vibration were accomplished by the sECM/MC hydrogel in paralyzed vocal fold which were confirmed by laryngoscope, histology and a high-speed imaging system. There were increased number of collagen fibers and fatty granules at the injection site without significant inflammation or fibrosis. Overall, these results indicate that the sECM/MC hydrogel can enhance vocal function in paralyzed vocal folds without early resorption and has potential as a promising material for injection laryngoplasty for stable vocal fold augmentation which can overcome the shortcomings of autologous fat such as unpredictable duration and morbidity associated with the fat harvest.

Inert gas narcosis has no influence on thermo-tactile sensation.

Science.gov (United States)

Jakovljević, Miroljub; Vidmar, Gaj; Mekjavic, Igor B

2012-05-01

Contribution of skin thermal sensors under inert gas narcosis to the raising hypothermia is not known. Such information is vital for understanding the impact of narcosis on behavioural thermoregulation, diver safety and judgment of thermal (dis)comfort in the hyperbaric environment. So this study aimed at establishing the effects of normoxic concentration of 30% nitrous oxide (N(2)O) on thermo-tactile threshold sensation by studying 16 subjects [eight females and eight males; eight sensitive (S) and eight non-sensitive (NS) to N(2)O]. Their mean (SD) age was 22.1 (1.8) years, weight 72.8 (15.3) kg, height 1.75 (0.10) m and body mass index 23.8 (3.8) kg m(-2). Quantitative thermo-tactile sensory testing was performed on forearm, upper arm and thigh under two experimental conditions: breathing air (air trial) and breathing normoxic mixture of 30% N(2)O (N(2)O trial) in the mixed sequence. Difference in thermo-tactile sensitivity thresholds between two groups of subjects in two experimental conditions was analysed by 3-way mixed-model analysis of covariance. There were no statistically significant differences in thermo-tactile thresholds either between the Air and N(2)O trials, or between S and NS groups, or between females and males, or with respect to body mass index. Some clinically insignificant lowering of thermo-tactile thresholds occurred only for warm thermo-tactile thresholds on upper arm and thigh. The results indicated that normoxic mixture of 30% N(2)O had no influence on thermo-tactile sensation in normothermia.

Enzymatic mineralization of gellan gum hydrogel for bone tissue-engineering applications and its enhancement by polydopamine

NARCIS (Netherlands)

Douglas, T.E.L.; Wlodarczyk, M.; Pamula, E.; Declercq, H.A.; Mulder, E.L.W. de; Bucko, M.M.; Balcaen, L.; Vanhaecke, F.; Cornelissen, R.; Dubruel, P.; Jansen, J.A.; Leeuwenburgh, S.C.G.

2014-01-01

Interest is growing in the use of hydrogels as bone tissue-engineering (TE) scaffolds due to advantages such as injectability and ease of incorporation of active substances such as enzymes. Hydrogels consisting of gellan gum (GG), an inexpensive calcium-crosslinkable polysaccharide, have been

Enabling Junction Temperature Estimation via Collector-Side Thermo-Sensitive Electrical Parameters through Emitter Stray Inductance in High-Power IGBT Modules

DEFF Research Database (Denmark)

Luo, Haoze; Li, Wuhua; Iannuzzo, Francesco

2018-01-01

This paper proposes the adoption of the inherent emitter stray inductance LeE in high-power insulated gate bipolar transistor (IGBT) modules as a new dynamic thermo-sensitive electrical parameter (d-TSEP). Furthermore, a family of 14 derived dynamic TSEP candidates has been extracted and classified...

Development and characterization of hydrogels based on natural polysaccharides: Policaju and chitosan

Energy Technology Data Exchange (ETDEWEB)

Soares, Paulo A.G. [Departamento de Bioquímica, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, 50670-420 Recife, PE (Brazil); Laboratório de Imunopatologia Keizo Asami-LIKA, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, 50670-901 Recife, PE (Brazil); Bourbon, Ana I.; Vicente, António A. [Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho (UMINHO), Campus de Gualtar, 4710-057 Braga (Portugal); Andrade, Cesar A.S. [Departamento de Bioquímica, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, 50670-420 Recife, PE (Brazil); Barros, Wilson [Departamento de Física, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, 50670-420 Recife, PE (Brazil); Correia, Maria T.S. [Departamento de Bioquímica, Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego, s/n, Cidade Universitária, 50670-420 Recife, PE (Brazil); Pessoa, Adalberto [Faculdade de Ciências Farmacêuticas, Universidade de São Paulo (USP), Av. Lineu Prestes, 580, Butantã, 05508-000 São Paulo, SP (Brazil); and others

2014-09-01

The development of hydrogels based on natural polysaccharides was investigated by preparing mixtures of policaju/chitosan at weight ratios of 1:4 and 2:3. Utilizing dynamic light scattering (DLS) techniques for these mixtures, an increase on the hydrodynamic particle radius was observed varying their pH from 3.0 to 12.0. Furthermore, a reduction of ζ-potential was also observed for the same pH interval. Following rounds of drying/hydration cycles at a specific pH value, hydrogel matrices were formed. The pore size distribution of these formed hydrogels was examined using scanning electron microscopy. Further FT-IR analyses confirmed a physical interaction between the polysaccharides policaju and chitosan. Swelling experiments revealed water uptake values, after 24 h of immersion in water, close to 270% for 1:4, and 320% for 2:3 hydrogels. Finally, rheological measurements were then conducted in order to confirm hydrogel viscoelastic features. These results indicate a promising road to biomaterials fabrication and biomedical applications. - Highlights: • POLI–CHI hydrogels were obtained by direct injection and extrusion. • POLI–CHI hydrated hydrogels have 4.2 times their dry weight. • Due to the high water absorption POLI–CHI hydrogels are extremely soft. • POLI–CHI hydrogels can be used in cosmetic and medical industry.

In situ spray deposition of cell-loaded, thermally and chemically gelling hydrogel coatings for tissue regeneration.

Science.gov (United States)

Pehlivaner Kara, Meryem O; Ekenseair, Adam K

2016-10-01

In this study, the efficacy of creating cellular hydrogel coatings on warm tissue surfaces through the minimally invasive, sprayable delivery of thermoresponsive liquid solutions was investigated. Poly(N-isopropylacrylamide)-based (pNiPAAm) thermogelling macromers with or without addition of crosslinking polyamidoamine (PAMAM) macromers were synthesized and used to produce in situ forming thermally and chemically gelling hydrogel systems. The effect of solution and process parameters on hydrogel physical properties and morphology was evaluated and compared to poly(ethylene glycol) and injection controls. Smooth, fast, and conformal hydrogel coatings were obtained when pNiPAAm thermogelling macromers were sprayed with high PAMAM concentration at low pressure. Cellular hydrogel coatings were further fabricated by different spraying techniques: single-stream, layer-by-layer, and dual stream methods. The impact of spray technique, solution formulation, pressure, and spray solution viscosity on the viability of fibroblast and osteoblast cells encapsulated in hydrogels was elucidated. In particular, the early formation of chemically crosslinked micronetworks during bulk liquid flow was shown to significantly affect cell viability under turbulent conditions compared to injectable controls. The results demonstrated that sprayable, in situ forming hydrogels capable of delivering cell populations in a homogeneous therapeutic coating on diseased tissue surfaces offer promise as novel therapies for applications in regenerative medicine. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2383-2393, 2016. © 2016 Wiley Periodicals, Inc.

Hydrogel-embedded endothelial progenitor cells evade LPS and mitigate endotoxemia.

Science.gov (United States)

Ghaly, Tammer; Rabadi, May M; Weber, Mia; Rabadi, Seham M; Bank, Michael; Grom, John M; Fallon, John T; Goligorsky, Michael S; Ratliff, Brian B

2011-10-01

Sepsis and its complications are associated with poor clinical outcomes. The circulatory system is a well-known target of lipopolysaccharide (LPS). Recently, several clinical studies documented mobilization of endothelial progenitor cells (EPCs) during endotoxemia, with the probability of patients' survival correlating with the rise in circulating EPCs. This fact combined with endotoxemia-induced vascular injury led us to hypothesize that the developing functional EPC incompetence could impede vascular repair and that adoptive transfer of EPCs could improve hemodynamics in endotoxemia. We used LPS injection to model endotoxemia. EPCs isolated from endotoxemic mice exhibited impaired clonogenic potential and LPS exerted Toll-like receptor 4-mediated cytotoxic effects toward EPCs, which was mitigated by embedding them in hyaluronic acid (HA) hydrogels. Therefore, intact EPCs were either delivered intravenously or embedded within pronectin-coated HA hydrogels. Adoptive transfer of EPCs in LPS-injected mice improved control of blood pressure and reduced hepatocellular and renal dysfunction. Specifically, EPC treatment was associated with the restoration of renal microcirculation and improved renal function. EPC therapy was most efficient when cells were delivered embedded in HA hydrogel. These findings establish major therapeutic benefits of adoptive transfer of EPCs, especially when embedded in HA hydrogels, in mice with LPS-induced endotoxemia, and they argue that hemodynamic and renal abnormalities of endotoxemia are in significant part due to developing incompetence of endogenous EPCs.

Sensitization or tolerance to Mycobacterium leprae antigen by route of injection

Energy Technology Data Exchange (ETDEWEB)

Shepard, C.C.; Walker, L.L.; Van Landingham, R.M.; Ye, S.Z.

1982-11-01

Aqueous suspensions of heat-killed Mycobacterium leprae in a dose of 10(7) organisms were highly immunogenic when injected intradermally (i.d.). The same dose of bacteria did not sensitize when given intraperitoneally (i.p.) or intravenously (i.v.), and did so only minimally at best when given subcutaneously. The i.d. route was the most immunogenic for sheep erythrocytes also. M. leprae injected i.p. or i.v. stimulated immune tolerance to M. leprae challenge i.d. In older mice (greater than or equal to 8 weeks), the i.v. injections gave more complete tolerance. Mice that had been rendered tolerant by i.v. injections maintained their tolerance for at least 168 days. Prior UV irradiation of intact mice prevented sensitization by the i.d. route. In normal mice, living M. bovis BCG given i.d. produced good sensitization to M. leprae. Mice that had been made tolerant by i.v. injection of M. leprae could be partially sensitized to M. leprae by i.d. immunization with BCG; mixtures of living BCG and heat-killed M. leprae were no more effective than BCG alone. These findings appear to have relevance to the pathogenesis of lepromatous leprosy and its immunoprophylaxis.

Sensitization or tolerance to Mycobacterium leprae antigen by route of injection

International Nuclear Information System (INIS)

Shepard, C.C.; Walker, L.L.; Van Landingham, R.M.; Ye, S.Z.

1982-01-01

Aqueous suspensions of heat-killed Mycobacterium leprae in a dose of 10(7) organisms were highly immunogenic when injected intradermally (i.d.). The same dose of bacteria did not sensitize when given intraperitoneally (i.p.) or intravenously (i.v.), and did so only minimally at best when given subcutaneously. The i.d. route was the most immunogenic for sheep erythrocytes also. M. leprae injected i.p. or i.v. stimulated immune tolerance to M. leprae challenge i.d. In older mice (greater than or equal to 8 weeks), the i.v. injections gave more complete tolerance. Mice that had been rendered tolerant by i.v. injections maintained their tolerance for at least 168 days. Prior UV irradiation of intact mice prevented sensitization by the i.d. route. In normal mice, living M. bovis BCG given i.d. produced good sensitization to M. leprae. Mice that had been made tolerant by i.v. injection of M. leprae could be partially sensitized to M. leprae by i.d. immunization with BCG; mixtures of living BCG and heat-killed M. leprae were no more effective than BCG alone. These findings appear to have relevance to the pathogenesis of lepromatous leprosy and its immunoprophylaxis

Human Adipose Tissue Derived Extracellular Matrix and Methylcellulose Hydrogels Augments and Regenerates the Paralyzed Vocal Fold.

Directory of Open Access Journals (Sweden)

Dong Wook Kim

Full Text Available Vocal fold paralysis results from various etiologies and can induce voice changes, swallowing complications, and issues with aspiration. Vocal fold paralysis is typically managed using injection laryngoplasty with fat or synthetic polymers. Injection with autologous fat has shown excellent biocompatibility. However, it has several disadvantages such as unpredictable resorption rate, morbidities associated with liposuction procedure which has to be done in operating room under general anesthesia. Human adipose-derived extracellular matrix (ECM grafts have been reported to form new adipose tissue and have greater biostability than autologous fat graft. Here, we present an injectable hydrogel that is constructed from adipose tissue derived soluble extracellular matrix (sECM and methylcellulose (MC for use in vocal fold augmentation. Human sECM derived from adipose tissue was extracted using two major steps-ECM was isolated from human adipose tissue and was subsequently solubilized. Injectable sECM/MC hydrogels were prepared by blending of sECM and MC. Sustained vocal fold augmentation and symmetric vocal fold vibration were accomplished by the sECM/MC hydrogel in paralyzed vocal fold which were confirmed by laryngoscope, histology and a high-speed imaging system. There were increased number of collagen fibers and fatty granules at the injection site without significant inflammation or fibrosis. Overall, these results indicate that the sECM/MC hydrogel can enhance vocal function in paralyzed vocal folds without early resorption and has potential as a promising material for injection laryngoplasty for stable vocal fold augmentation which can overcome the shortcomings of autologous fat such as unpredictable duration and morbidity associated with the fat harvest.

Immobilization of pH-sensitive CdTe Quantum Dots in a Poly(acrylate) Hydrogel for Microfluidic Applications

Science.gov (United States)

Franke, M.; Leubner, S.; Dubavik, A.; George, A.; Savchenko, T.; Pini, C.; Frank, P.; Melnikau, D.; Rakovich, Y.; Gaponik, N.; Eychmüller, A.; Richter, A.

2017-04-01

Microfluidic devices present the basis of modern life sciences and chemical information processing. To control the flow and to allow optical readout, a reliable sensor material that can be easily utilized for microfluidic systems is in demand. Here, we present a new optical readout system for pH sensing based on pH sensitive, photoluminescent glutathione capped cadmium telluride quantum dots that are covalently immobilized in a poly(acrylate) hydrogel. For an applicable pH sensing the generated hybrid material is integrated in a microfluidic sensor chip setup. The hybrid material not only allows in situ readout, but also possesses valve properties due to the swelling behavior of the poly(acrylate) hydrogel. In this work, the swelling property of the hybrid material is utilized in a microfluidic valve seat, where a valve opening process is demonstrated by a fluid flow change and in situ monitored by photoluminescence quenching. This discrete photoluminescence detection (ON/OFF) of the fluid flow change (OFF/ON) enables upcoming chemical information processing.

Engineering bone regeneration with novel cell-laden hydrogel microfiber-injectable calcium phosphate scaffold

Energy Technology Data Exchange (ETDEWEB)

Song, Yang [Department of Prosthodontics, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, Guangdong (China); Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Zhang, Chi [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan 610041 (China); Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Wang, Ping, E-mail: dentistping@gmail.com [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Wang, Lin [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); VIP Integrated Department, School and Hospital of Stomatology, Jilin University, Changchun, Jilin 130011 (China); Bao, Chunyun [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan 610041 (China); Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Weir, Michael D.; Reynolds, Mark A. [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Ren, Ke [Department of Neural and Pain Sciences, School of Dentistry, Program in Neuroscience, University of Maryland, Baltimore, MD 21201 (United States); Zhao, Liang, E-mail: lzhaonf@126.com [Department of Endodontics, Periodontics and Prosthodontics, University of Maryland School of Dentistry, Baltimore, MD 21201 (United States); Department of Orthopaedic Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515 (China); and others

2017-06-01

Cell-based tissue engineering is promising to create living functional tissues for bone regeneration. The implanted cells should be evenly distributed in the scaffold, be fast-released to the defect and maintain high viability in order to actively participate in the regenerative process. Herein, we report an injectable calcium phosphate cement (CPC) scaffold containing cell-encapsulating hydrogel microfibers with desirable degradability that could deliver cells in a timely manner and maintain cell viability. Microfibers were synthesized using partially-oxidized alginate with various concentrations (0–0.8%) of fibrinogen to optimize the degradation rate of the alginate-fibrin microfibers (Alg-Fb MF). A fibrin concentration of 0.4% in Alg-Fb MF resulted in the greatest enhancement of cell migration, release and proliferation. Interestingly, a significant amount of cell–cell contact along the long-axis of the microfibers was established in Alg-0.4%Fb MF as early as day 2. The injectable tissue engineered construct for bone reconstruct was fabricated by mixing the fast-degradable Alg-0.4%Fb MF with CPC paste at 1:1 volume ratio. In vitro study showed that cells re-collected from the construct maintained good viability and osteogenic potentials. In vivo study demonstrated that the hBMSC-encapsulated CPC-MF tissue engineered construct displayed a robust capacity for bone regeneration. At 12 weeks after implantation, osseous bridge in the rat mandibular defect was observed in CPC-MF-hBMSCs group with a new bone area fraction of (42.1 ± 7.8) % in the defects, which was > 3-fold that of the control group. The novel tissue-engineered construct presents an excellent prospect for a wide range of dental, craniofacial and orthopedic applications. - Highlights: • Microfibers protected cells during CPC mixing and injection, and supported the viability, migration and differentiation of encapsulated cells. • Cells re-collected from the construct maintained good viability

Engineering bone regeneration with novel cell-laden hydrogel microfiber-injectable calcium phosphate scaffold

International Nuclear Information System (INIS)

Song, Yang; Zhang, Chi; Wang, Ping; Wang, Lin; Bao, Chunyun; Weir, Michael D.; Reynolds, Mark A.; Ren, Ke; Zhao, Liang

2017-01-01

Cell-based tissue engineering is promising to create living functional tissues for bone regeneration. The implanted cells should be evenly distributed in the scaffold, be fast-released to the defect and maintain high viability in order to actively participate in the regenerative process. Herein, we report an injectable calcium phosphate cement (CPC) scaffold containing cell-encapsulating hydrogel microfibers with desirable degradability that could deliver cells in a timely manner and maintain cell viability. Microfibers were synthesized using partially-oxidized alginate with various concentrations (0–0.8%) of fibrinogen to optimize the degradation rate of the alginate-fibrin microfibers (Alg-Fb MF). A fibrin concentration of 0.4% in Alg-Fb MF resulted in the greatest enhancement of cell migration, release and proliferation. Interestingly, a significant amount of cell–cell contact along the long-axis of the microfibers was established in Alg-0.4%Fb MF as early as day 2. The injectable tissue engineered construct for bone reconstruct was fabricated by mixing the fast-degradable Alg-0.4%Fb MF with CPC paste at 1:1 volume ratio. In vitro study showed that cells re-collected from the construct maintained good viability and osteogenic potentials. In vivo study demonstrated that the hBMSC-encapsulated CPC-MF tissue engineered construct displayed a robust capacity for bone regeneration. At 12 weeks after implantation, osseous bridge in the rat mandibular defect was observed in CPC-MF-hBMSCs group with a new bone area fraction of (42.1 ± 7.8) % in the defects, which was > 3-fold that of the control group. The novel tissue-engineered construct presents an excellent prospect for a wide range of dental, craniofacial and orthopedic applications. - Highlights: • Microfibers protected cells during CPC mixing and injection, and supported the viability, migration and differentiation of encapsulated cells. • Cells re-collected from the construct maintained good viability

Facilitation of facial nerve regeneration using chitosan-β-glycerophosphate-nerve growth factor hydrogel.

Science.gov (United States)

Chao, Xiuhua; Xu, Lei; Li, Jianfeng; Han, Yuechen; Li, Xiaofei; Mao, YanYan; Shang, Haiqiong; Fan, Zhaomin; Wang, Haibo

2016-06-01

Conclusion C/GP hydrogel was demonstrated to be an ideal drug delivery vehicle and scaffold in the vein conduit. Combined use autologous vein and NGF continuously delivered by C/GP-NGF hydrogel can improve the recovery of facial nerve defects. Objective This study investigated the effects of chitosan-β-glycerophosphate-nerve growth factor (C/GP-NGF) hydrogel combined with autologous vein conduit on the recovery of damaged facial nerve in a rat model. Methods A 5 mm gap in the buccal branch of a rat facial nerve was reconstructed with an autologous vein. Next, C/GP-NGF hydrogel was injected into the vein conduit. In negative control groups, NGF solution or phosphate-buffered saline (PBS) was injected into the vein conduits, respectively. Autologous implantation was used as a positive control group. Vibrissae movement, electrophysiological assessment, and morphological analysis of regenerated nerves were performed to assess nerve regeneration. Results NGF continuously released from C/GP-NGF hydrogel in vitro. The recovery rate of vibrissae movement and the compound muscle action potentials of regenerated facial nerve in the C/GP-NGF group were similar to those in the Auto group, and significantly better than those in the NGF group. Furthermore, larger regenerated axons and thicker myelin sheaths were obtained in the C/GP-NGF group than those in the NGF group.

Cytocompatible in situ forming chitosan/hyaluronan hydrogels via a metal-free click chemistry for soft tissue engineering.

Science.gov (United States)

Fan, Ming; Ma, Ye; Mao, Jiahui; Zhang, Ziwei; Tan, Huaping

2015-07-01

Injectable hydrogels are important cell scaffolding materials for tissue engineering and regenerative medicine. Here, we report a new class of biocompatible and biodegradable polysaccharide hydrogels derived from chitosan and hyaluronan via a metal-free click chemistry, without the addition of copper catalyst. For the metal-free click reaction, chitosan and hyaluronan were modified with oxanorbornadiene (OB) and 11-azido-3,6,9-trioxaundecan-1-amine (AA), respectively. The gelation is attributed to the triazole ring formation between OB and azido groups of polysaccharide derivatives. The molecular structures were verified by FT-IR spectroscopy and elemental analysis, giving substitution degrees of 58% and 47% for chitosan-OB and hyaluronan-AA, respectively. The in vitro gelation, morphologies, equilibrium swelling, compressive modulus and degradation of the composite hydrogels were examined. The potential of the metal-free hydrogel as a cell scaffold was demonstrated by encapsulation of human adipose-derived stem cells (ASCs) within the gel matrix in vitro. Cell culture showed that this metal-free hydrogel could support survival and proliferation of ASCs. A preliminary in vivo study demonstrated the usefulness of the hydrogel as an injectable scaffold for adipose tissue engineering. These characteristics provide a potential opportunity to use the metal-free click chemistry in preparation of biocompatible hydrogels for soft tissue engineering applications. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Functionalization of oligo(poly(ethylene glycol)fumarate) hydrogels with finely dispersed calcium phosphate nanocrystals for bone-substituting purposes.

NARCIS (Netherlands)

Leeuwenburgh, S.C.G.; Jansen, J.A.; Mikos, A.G.

2007-01-01

Biodegradable polymers that can be processed into injectable hydrogel matrices are promising candidates for bone-substituting purposes. Furthermore, by incorporating degradable calcium phosphate (CaP) particles and growth factors into these hydrogel matrices, a bone construct can be designed which

Sustained Local Release of Methylprednisolone From a Thiol-Acrylate Poly(Ethylene Glycol) Hydrogel for Treating Chronic Compressive Radicular Pain.

Science.gov (United States)

Slotkin, Jonathan R; Ness, Jennifer K; Snyder, Kristin M; Skiles, Amanda A; Woodard, Eric J; OʼShea, Timothy; Layer, Rick T; Aimetti, Alex A; Toms, Steven A; Langer, Robert; Tapinos, Nikos

2016-04-01

A preclinical animal model of chronic ligation of the sciatic nerve was used to compare the effectiveness of a slow-release hydrogel carrying methylprednisolone to methylprednisolone injection alone, which simulates the current standard of care for chronic compressive radiculopathy (CR). To extend the short-term benefits of steroid injections by using a nonswelling, biodegradable hydrogel as carrier to locally release methylprednisolone in a regulated and sustained way at the site of nerve compression. CR affects millions worldwide annually, and is a cause of costly disability with significant societal impact. Currently, a leading nonsurgical therapy involves epidural injection of steroids to temporarily alleviate the pain associated with CR. However, an effective way to extend the short-term effect of steroid treatment to address the chronic component of CR does not exist. We induced chronic compression injury of the sciatic nerves of rats by permanent ligation. Forty-eight hours later we injected our methylprednisolone infused hydrogel and assessed the effectiveness of our treatment for 4 weeks. We quantified mechanical hyperalgesia using a Dynamic Plantar Aesthesiometer (Ugo Basile, Stoelting Co., IL, USA), whereas gait analysis was conducted using the Catwalk automated gait analysis platform (Noldus, Leesburg, VA, USA). Macrophage staining was performed with immunohistochemistry and quantification of monocyte chemoattractant protein-1 in sciatic nerve lysates was performed with multiplex immunoassay using a SECTOR Imager 2400A (Meso Scale Discovery, Rockville, MA, USA). We demonstrate that using the hydrogel to deliver methylprednisolone results in significant (P pain in an animal model of chronic CR. Our steroid-infused hydrogel could be an effective extender of the short-term benefits of epidural steroid injections for patients with chronic compression-induced radicular pain. N/A.

A Micro CO2 Gas Sensor Based on Sensing of pH-Sensitive Hydrogel Swelling by Means of a Pressure Sensor

NARCIS (Netherlands)

Herber, S.; Bomer, Johan G.; Olthuis, Wouter; Bergveld, Piet; van den Berg, Albert

2005-01-01

In this paper a sensor is presented for the detection of carbon dioxide gas inside the stomach in order to diagnose gastrointestinal ischemia. The operational principle of the sensor is measuring the CO2 induced pressure generation of a confined pH-sensitive hydrogel by means of a micro pressure

Fluorescent probe encapsulated hydrogel microsphere for selective and reversible detection of Hg{sup 2+}

Energy Technology Data Exchange (ETDEWEB)

Song, Zhenhu; Wang, Fang; Qiang, Jian; Zhang, Zhijie; Chen, Yahui; Wang, Yong; Zhang, Wei; Chen, Xiaoqiang

2017-03-15

We developed a simple and sensitive hydrogel sensor in the form of microspheres by using fluorescence probe encapsulated within a hydrogel matrix for the detection of Hg{sup 2+}. The traditional fluorescence probes suspended in solution are not transportable and recoverable. To overcome these disadvantages, we devised poly(ethylene glycol) diacrylate-based hydrogel microspheres in which fluorescence probe (R19S) was embedded at high density. The functionalized hydrogel microspheres were prepared by combining a microfluidic device with UV light. The hydrogel microspheres-based sensor exhibited good selectivity to Hg{sup 2+} among various metal ions and high sensitivity with a detection limit of 90 nM. Furthermore, after binding with Hg{sup 2+}, the R19S encapsulated hydrogel microspheres can be separated from testing samples easily and treated with the solution containing KI to remove Hg{sup 2+} and realize reusable detection. The current work may offer a new method for Hg{sup 2+} recognition with a more efficient manner.

On nonlinear thermo-electro-elasticity.

Science.gov (United States)

Mehnert, Markus; Hossain, Mokarram; Steinmann, Paul

2016-06-01

Electro-active polymers (EAPs) for large actuations are nowadays well-known and promising candidates for producing sensors, actuators and generators. In general, polymeric materials are sensitive to differential temperature histories. During experimental characterizations of EAPs under electro-mechanically coupled loads, it is difficult to maintain constant temperature not only because of an external differential temperature history but also because of the changes in internal temperature caused by the application of high electric loads. In this contribution, a thermo-electro-mechanically coupled constitutive framework is proposed based on the total energy approach. Departing from relevant laws of thermodynamics, thermodynamically consistent constitutive equations are formulated. To demonstrate the performance of the proposed thermo-electro-mechanically coupled framework, a frequently used non-homogeneous boundary-value problem, i.e. the extension and inflation of a cylindrical tube, is solved analytically. The results illustrate the influence of various thermo-electro-mechanical couplings.

A thermo-sensitive purple leaf rice mutant--PLM12 and its genetical study

International Nuclear Information System (INIS)

Wu Guanting; Wang Xianyu; Jin Wei

2001-01-01

PLM12 was a thermo-sensitive purple leaf mutant selected from Indica rice variety Luqingzao 1 treated with pingyangmycin in combination with γ-rays, and for display of its mutant character, a relatively high temperature was required. Compared with its original parent, many major agronomic traits of PLM12 changed to varied extents. Based on spikelet cutting experiment, it was believed that significant decreases in number of filled grains per panicle, fertility, and 1000-grain weight in PLM12 resulted mainly from a great decline in photosynthetic capacity and serious lack of photosynthate in purple leaves. It was indicated by genetic analysis that expression of the mutant phenotype in PLM12 was conditioned by a single recessive major nuclear gene and modified by several minor genes

Injectable systems and implantable conduits for peripheral nerve repair

International Nuclear Information System (INIS)

Lin, Yen-Chih; Marra, Kacey G

2012-01-01

Acute sensory problems following peripheral nerve injury include pain and loss of sensation. Approximately 360 000 people in the United States suffer from upper extremity paralytic syndromes every year. Restoration of sufficient functional recovery after long-gap peripheral nerve damage remains a clinical challenge. Potential nerve repair therapies have increased in the past decade as the field of tissue engineering expands. The following review describes the use of biomaterials in nerve tissue engineering. Namely, the use of both synthetic and natural biomaterials, including non-degradable and degradable nerve grafts, is addressed. The enhancement of axonal regeneration can be achieved by further modification of the nerve guides. These approaches include injectable hydrogel fillers, controlled drug delivery systems, and cell incorporation. Hydrogels are a class of liquid–gel biomaterials with high water content. Injectable and gelling hydrogels can serve as growth factor delivery vehicles and cell carriers for tissue engineering applications. While natural hydrogels and polymers are suitable for short gap nerve repair, the use of polymers for relatively long gaps remains a clinical challenge. (paper)

Novel Hydrogels from Renewable Resources

Science.gov (United States)

Karaaslan, Muzafer Ahmet

2011-12-01

The cell wall of most plant biomass from forest and agricultural resources consists of three major polymers, cellulose, hemicellulose and lignin. Of these, hemicelluloses have gained increasing attention as sustainable raw materials. In the first part of this study, novel pH-sensitive semi-IPN hydrogels based on hemicelluloses and chitosan were prepared using glutaraldehyde as the crosslinking agent. The hemicellulose isolated from aspen was analyzed for sugar content by HPLC, and its molecular weight distribution was determined by high performance size exclusion chromatography. Results revealed that hemicellulose had a broad molecular weight distribution with a fair amount of polymeric units, together with xylose, arabinose and glucose. The effect of hemicellulose content on mechanical properties and swelling behavior of hydrogels were investigated. The semi-IPNs hydrogel structure was confirmed by FT-IR, X-ray study and ninhydrin assay method. X-ray analysis showed that higher hemicellulose contents yielded higher crystallinity. Mechanical properties were mainly dependent on the crosslink density and average molecular weight between crosslinks. Swelling ratios increased with increasing hemicellulose content and were high at low pH values due to repulsion between similarly charged groups. In vitro release study of a model drug showed that these semi-IPN hydrogels could be used for controlled drug delivery into gastric fluid. The aim of the second part of this study was to control the crosslink density and the mechanical properties of hemicellulose/chitosan semi-IPN hydrogels by changing the crosslinking sequence. It has been hypothesized that by performing the crosslinking step before introducing hemicellulose, covalent crosslinking of chitosan would not be hindered and therefore more and/or shorter crosslinks could be formed. Furthermore, additional secondary interactions and crystalline domains introduced through hemicellulose could be favorable in terms of

Hydrogel based cartilaginous tissue regeneration: recent insights and technologies.

Science.gov (United States)

Chuah, Yon Jin; Peck, Yvonne; Lau, Jia En Josias; Hee, Hwan Tak; Wang, Dong-An

2017-03-28

Hydrogels have been extensively employed as an attractive biomaterial to address numerous existing challenges in the fields of regenerative medicine and research because of their unique properties such as the capability to encapsulate cells, high water content, ease of modification, low toxicity, injectability, in situ spatial fit and biocompatibility. These inherent properties have created many opportunities for hydrogels as a scaffold or a cell/drug carrier in tissue regeneration, especially in the field of cartilaginous tissue such as articular cartilage and intervertebral discs. A concise overview of the anatomy/physiology of these cartilaginous tissues and their pathophysiology, epidemiology and existing clinical treatments will be briefly described. This review article will discuss the current state-of-the-art of various polymers and developing strategies that are explored in establishing different technologies for cartilaginous tissue regeneration. In particular, an innovative approach to generate scaffold-free cartilaginous tissue via a transient hydrogel scaffolding system for disease modeling to pre-clinical trials will be examined. Following that, the article reviews numerous hydrogel-based medical implants used in clinical treatment of osteoarthritis and degenerated discs. Last but not least, the challenges and future directions of hydrogel based medical implants in the regeneration of cartilaginous tissue are also discussed.

Assessment of core thermo-hydrodynamic models of REFLA-1D with CCTF data

International Nuclear Information System (INIS)

Okubo, Tsutomu; Murao, Yoshio

1983-07-01

In order to assess the core thermo-hydrodynamic models of REFLA-1D/MODE3, which is the latest version of REFLA-1D, several calculations of the core thermo-hydrodynamics have been performed for the CCTF Core-I series tests. The measured initial and boundary conditions were used for these calculations. The calculational results showed that the water accumulation model of Case 2 could predict the CCTF results fairly well as it could for the JAERI small scale facility. The calculated results for the base case and the EM tests were in good agreement with the CCTF data. The parameter effects, such as system pressure, initial clad temperature, Acc injection rate, LPCI injection rate and initial down-comer wall temperature, were predicted correctly, except for the high system pressure and the high LPCI injection rate tests. (author)

Healing wounds - radiation processing technology for hydrogel dressing

International Nuclear Information System (INIS)

Varshney, Lalit

2009-01-01

Uses of hydrogels are known and have several applications in medical field. Drug delivery devices, contact lenses, wound dressing, artificial cartilage's or membranes, vascular prosthesis, gel coated catheters etc., are some of the examples. Due to direct relevance to human health, scientists have been continuously exploring these systems. Generally, hydro (water) gels contain 30-90% of water entrapped in a three dimensional network structure of a hydrophilic polymer. The large water content makes them highly bio-compatible and therefore preferred for use as biomaterials. Some of the hydrophilic polymers used in these applications include poly (vinyl pyrrolidone), poly (ethylene oxide), poly (vinyl alcohol) and poly (acrylic acid ). Depending upon the nature of application, the size of these hydrogel can vary from nanometers (nanogels, injectable hydrogels) to centimeters to meters (wound dressing, fire blankets, drug delivery devices and implants). BARC hydrogel dressings have been so far used for treating burns, leprosy ulcers, animal bites, diabetic foot ulcers, herpes, fresh scars, bullet injuries, boils, pimples, sun burns, abrasion, surgical wounds of breast cancer, as bolus for radiation therapy in cancer etc. The use of gels have shown excellent result in diabetic ulcers which definitely provides an alternate to expensive biotech products and relief to expanding population of diabetics in India. Its application and some of the examples are shown in the paper. Other hydrogel based products which are under development in the authors laboratory are radiation processed silver nano-particle hydrogels to treat infected wounds and fire blankets for whole body coverage for protection from fire for defense personnel and fire service people

Preparation and properties of EDC/NHS mediated crosslinking poly (gamma-glutamic acid)/epsilon-polylysine hydrogels

Energy Technology Data Exchange (ETDEWEB)

Hua, Jiachuan [Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387 (China); School of Textiles, Tianjin Polytechnic University, Tianjin 300387 (China); Li, Zheng, E-mail: lizheng_nx@163.com [Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387 (China); School of Textiles, Tianjin Polytechnic University, Tianjin 300387 (China); Xia, Wen; Yang, Ning; Gong, Jixian [Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387 (China); School of Textiles, Tianjin Polytechnic University, Tianjin 300387 (China); Zhang, Jianfei, E-mail: zhangjianfei1960@126.com [Key Laboratory of Advanced Textile Composites, Tianjin Polytechnic University, Ministry of Education, Tianjin 300387 (China); School of Textiles, Tianjin Polytechnic University, Tianjin 300387 (China); Qiao, Changsheng [Key Laboratory of Industrial Microbiology, Tianjin University of Science and Technology, Ministry of Education, Tianjin 300457 (China)

2016-04-01

In this paper, a novel pH-sensitive poly (amino acid) hydrogel based on poly γ-glutamic acid (γ-PGA) and ε-polylysine (ε-PL) was prepared by carbodiimide (EDC) and N-hydroxysuccinimide (NHS) mediated polymerization. The influence of PGA/PL molar ratio and EDC/NHS concentration on the structure and properties was studied. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) proved that hydrogels were crosslinked through amide bond linkage, and the conversion rate of a carboxyl group could reach 96%. Scanning electron microscopy (SEM) results showed a regularly porous structure with 20 μm pore size in average. The gelation time in the crosslink process of PGA/PL hydrogels was within less than 5 min. PGA/PL hydrogels had excellent optical performance that was evaluated by a novel optotype method. Furthermore, PGA/PL hydrogels were found to be pH-sensitive, which could be adjusted to the pH of swelling media intelligently. The terminal pH of swelling medium could be controlled at 5 ± 1 after equilibrium when the initial pH was within 3–11. The swelling kinetics was found to follow a Voigt model in deionized water but a pseudo-second-order model in normal saline and phosphate buffer solution, respectively. The differential swelling degrees were attributed to the swelling theory based on the different ratio of –COOH/–NH{sub 2} and pore size in hydrogels. The results of mechanical property indicated that PGA/PL hydrogels were soft and elastic. Moreover, PGA/PL hydrogels exhibited excellent biocompatibility by cell proliferation experiment. PGA/PL hydrogels could be degraded in PBS solution and the degradation rate was decreased with the increase of the molar ratio of PL. Considering the simple preparation process and pH-sensitive property, these PGA/PL hydrogels might have high potential for use in medical and clinical fields. - Highlights: • We prepared a biocompatible and degradable poly amino acids hydrogel via EDC

A Hyaluronan-Based Injectable Hydrogel Improves the Survival and Integration of Stem Cell Progeny following Transplantation

Directory of Open Access Journals (Sweden)

Brian G. Ballios

2015-06-01

Full Text Available The utility of stem cells and their progeny in adult transplantation models has been limited by poor survival and integration. We designed an injectable and bioresorbable hydrogel blend of hyaluronan and methylcellulose (HAMC and tested it with two cell types in two animal models, thereby gaining an understanding of its general applicability for enhanced cell distribution, survival, integration, and functional repair relative to conventional cell delivery in saline. HAMC improves cell survival and integration of retinal stem cell (RSC-derived rods in the retina. The pro-survival mechanism of HAMC is ascribed to the interaction of the CD44 receptor with HA. Transient disruption of the retinal outer limiting membrane, combined with HAMC delivery, results in significantly improved rod survival and visual function. HAMC also improves the distribution, viability, and functional repair of neural stem and progenitor cells (NSCs. The HAMC delivery system improves cell transplantation efficacy in two CNS models, suggesting broad applicability.

Improved Concrete Materials with Hydrogel-Based Internal Curing Agents

Directory of Open Access Journals (Sweden)

Matthew J. Krafcik

2017-11-01

Full Text Available This research article will describe the design and use of polyelectrolyte hydrogel particles as internal curing agents in concrete and present new results on relevant hydrogel-ion interactions. When incorporated into concrete, hydrogel particles release their stored water to fuel the curing reaction, resulting in reduced volumetric shrinkage and cracking and thus increasing concrete service life. The hydrogel’s swelling performance and mechanical properties are strongly sensitive to multivalent cations that are naturally present in concrete mixtures, including calcium and aluminum. Model poly(acrylic acid(AA-acrylamide(AM-based hydrogel particles with different chemical compositions (AA:AM monomer ratio were synthesized and immersed in sodium, calcium, and aluminum salt solutions. The presence of multivalent cations resulted in decreased swelling capacity and altered swelling kinetics to the point where some hydrogel compositions displayed rapid deswelling behavior and the formation of a mechanically stiff shell. Interestingly, when incorporated into mortar, hydrogel particles reduced mixture shrinkage while encouraging the formation of specific inorganic phases (calcium hydroxide and calcium silicate hydrate within the void space previously occupied by the swollen particle.

Synthesis and properties of hemicelluloses-based semi-IPN hydrogels.

Science.gov (United States)

Peng, Feng; Guan, Ying; Zhang, Bing; Bian, Jing; Ren, Jun-Li; Yao, Chun-Li; Sun, Run-Cang

2014-04-01

Hemicelluloses were extracted from holocellulose of bamboo by alkaline treatment. The phosphorylated poly(vinyl alcohol) (P-PVA) samples with various substitution degrees were prepared through the esterification of PVA and phosphoric acid. A series of hydrogels of semi-interpenetrating polymeric networks (semi-IPN) composed of hemicelluloses-g-poly(acrylic acid) (HM-g-PAA) and the phosphorylated poly(vinyl alcohol) (P-PVA) were prepared by radical polymerization using potassium persulphate (KPS) as initiator. The HM-g-PAA networks were crosslinked by N,N-methylenebisacrylamide (MBA) as a crosslinking agent in the presence of linear P-PVA. FT-IR results confirmed that the hydrogels comprised a porous crosslink structure of P-PVA and HM with side chains that carried carboxylate and phosphorylate groups. SEM observations indicated that the incorporation of P-PVA induced highly porous structure, and P-PVA was uniformly dispersed in the polymeric network. The interior network structures of the semi-IPN matrix became more porous with increasing P-PVA. The TGA results showed that the thermo-decomposing temperature and thermal stability were increased effectively for intruding the chain of P-PVA. The maximum equilibrium swelling ratio of hydrogels in distilled water and 0.9 wt% sodium chloride solutions was up to 1085 g g(-1) and 87 g g(-1), respectively. The compressive strength increased with increasing the MBA/HM and P-PVA/HM ratios, and decreased with the increment of AA/HM ratio. Copyright © 2014 Elsevier B.V. All rights reserved.

Enhancement of Curcumin Bioavailability Using Nanocellulose Reinforced Chitosan Hydrogel

Directory of Open Access Journals (Sweden)

Thennakoon M. Sampath Udeni Gunathilake

2017-02-01

Full Text Available A unique biodegradable, superporous, swellable and pH sensitive nanocellulose reinforced chitosan hydrogel with dynamic mechanical properties was prepared for oral administration of curcumin. Curcumin, a less water-soluble drug was used due to the fact that the fast swellable, superporous hydrogel could release a water-insoluble drug to a great extent. CO2 gas foaming was used to fabricate hydrogel as it eradicates using organic solvents. Field emission scanning electron microscope images revealed that the pore size significantly increased with the formation of widely interconnected porous structure in gas foamed hydrogels. The maximum compression of pure chitosan hydrogel was 25.9 ± 1 kPa and it increased to 38.4 ± 1 kPa with the introduction of 0.5% cellulose nanocrystals. In vitro degradation of hydrogels was found dependent on the swelling ratio and the amount of CNC of the hydrogel. All the hydrogels showed maximum swelling ratios greater than 300%. The 0.5% CNC-chitosan hydrogel showed the highest swelling ratio of 438% ± 11%. FTIR spectrum indicated that there is no interaction between drug and ingredients present in hydrogels. The drug release occurred in non-Fickian (anomalous manner in simulated gastric medium. The drug release profiles of hydrogels are consistent with the data obtained from the swelling studies. After gas foaming of the hydrogel, the drug loading efficiency increased from 41% ± 2.4% to 50% ± 2.0% and release increased from 0.74 to 1.06 mg/L. The drug release data showed good fitting to Ritger-Peppas model. Moreover, the results revealed that the drug maintained its chemical activity after in vitro release. According to the results of this study, CNC reinforced chitosan hydrogel can be suggested to improve the bioavailability of curcumin for the absorption from stomach and upper intestinal tract.

Application of a hydrogel spacer for postoperative salvage radiotherapy of prostate cancer

International Nuclear Information System (INIS)

Pinkawa, Michael; Schubert, Carolin; Escobar-Corral, Nuria; Holy, Richard; Eble, Michael J.

2015-01-01

In contrast to primary radiotherapy, no reports are available for a hydrogel spacer application in postoperative salvage radiotherapy for prostate cancer. A 77-year-old patient presented 20 years after radical prostatectomy with a digitally palpable local recurrence at the urethrovesical anastomosis (PSA 5.5 ng/ml). The hydrogel spacer (10 ml, SpaceOAR trademark) was injected between the local recurrence and rectal wall under transrectal ultrasound guidance. Treatment planning was performed with an intensity-modulated technique up to a total dose of 76 Gy in 2-Gy fractions. The same planning was performed based on computed tomography before spacer injection for comparison. The local recurrence, initially directly on the rectal wall, could be displaced more than 1 cm from the rectal wall after hydrogel injection. With a mean total dose of 76 Gy to the planning target volume, rectal wall volumes included in the 70 Gy, 60 Gy, 50 Gy isodoses were 0 cm 3 , 0 cm 3 , and 0.4 cm 3 with a spacer and 2.9 cm 3 , 4.5 cm 3 , and 6.2 cm 3 without a spacer, respectively. The patient reported rectal urgency during radiotherapy, completely resolving after the end of treatment. The PSA level was 5.4 ng/ml a week before the end of radiotherapy and dropped to 0.9 ng/ml 5 months after radiotherapy. A hydrogel spacer was successfully applied for dose-escalated radiotherapy in a patient with macroscopic local prostate cancer recurrence at the urethrovesical anastomosis to decrease the dose at the rectal wall. This option can be considered in specifically selected patients. (orig.) [de

Study of chemically induced pressure generation of hydrogels under isochoric conditions using a microfabricated device

NARCIS (Netherlands)

Herber, S.; Eijkel, Jan C.T.; Olthuis, Wouter; Bergveld, Piet; van den Berg, Albert

2004-01-01

A method is proposed to study the behavior of stimulus-sensitive hydrogels under isochoric conditions. Freedom of swell movement of such a hydrogel was restricted in all directions by enclosing the hydrogel between a micropressure sensor and a porous cover. Water and external stimuli can be applied

[Injectable hydrogel functionalised with thrombocyte-rich solution and microparticles for accelerated cartilage regeneration].

Science.gov (United States)

Rampichová, M; Buzgo, M; Křížková, B; Prosecká, E; Pouzar, M; Štrajtová, L

2013-01-01

Articular cartilage defects arise due to injury or osteochondral disease such as osteonecrosis or osteochondritis dissecans. In adult patients cartilage has minimal ability to repair itself and the lesions develop into degenerative arthritis. Overcoming the low regenerative capacity of the cartilage cells and the Hayflick limit poses a challenge for the therapy of osteochondral defects. Composite scaffolds with appropriate biomechanical properties combined with a suitable blend of proliferation and differentiation factors could be a solution. The aim of this in vitro study was to develop a novel functionalised hydrogel with an integrated drug delivery system stimulating articular cartilage regeneration. Injectable collagen/ hyaluronic acid/fibrin composite hydrogel was mixed with nanofibre-based microparticles. These were loaded with ascorbic acid and dexamethasone. In addition, the effect of thrombocyte-rich solution (TRS) was studied. The gels seeded with mesenchymal stem cells (MSCs) were cultivated for 14 days. The viability, proliferation and morphology of the cells were evaluated using molecular and microscopic methods. Scaffold degradation was also assessed. The cultivation study showed that MSCs remained viable in all experimental groups, which indicated good biocompatibility of the gel. However, the number of cells in the groups enriched with microparticles was lower than in the other groups. On the other hand, confocal microscopy showed higher cell viability and rounded morphology of the cells, which can be associated with chodrogenic differentiation. The scaffolds containing microparticles showed significantly higher stability during the 14-day experiment. Our results suggest that the addition of microparticles to the scaffold improved cell differentiation into the chondrogenic lineage, resulting in a lower proliferation rate. Cell viability was better in the groups enriched with microparticles that served as an efficient drug delivery system. In

γ-Rays-induced synthesis of hydrogels of vinyl ethers with stimuli-sensitive behavior

International Nuclear Information System (INIS)

Nam, I.K.; Mun, G.A.; Urkimbaeva, P.I.; Nurkeeva, Z.S.

2003-01-01

γ-Radiation method was applied to synthesize novel water-soluble and water-swelling polymers. Vinyl ether of ethylene glycol (VEEG), vinyl butyl (VBE) and vinyl isobutyl (VIBE) ethers were used as monomers. The synthesis of VEEG-VBE and VEEG-VIBE copolymers was carried out in a wide range of feed composition and absorbed dose. It was found that the hydrophobic-hydrophilic balance of the copolymers could be delicately varied by the copolymer composition as well as by the chemical structure of the alkyl substitute in the hydrophobic moiety. The copolymers exhibit thermo-sensitive behavior in water solutions. The value of transition temperature is considerably decreased at a higher concentration of the hydrophobic component in the copolymer composition

The osteoinductive potential of printable, cell-laden hydrogel-ceramic composites.

NARCIS (Netherlands)

Fedorovich, N.E.; Leeuwenburgh, S.C.G.; Helm, Y.J. van der; Alblas, J.; Dhert, W.J.

2012-01-01

Hydrogels used as injectables or in organ printing often lack the appropriate stimuli to direct osteogenic differentiation of embedded multipotent stromal cells (MSCs), resulting in limited bone formation in these matrices. Addition of calcium phosphate (CaP) particles to the printing mixture is

Drug release from enzyme-mediated in situ-forming hydrogel based on gum tragacanth-tyramine conjugate.

Science.gov (United States)

Dehghan-Niri, Maryam; Tavakol, Moslem; Vasheghani-Farahani, Ebrahim; Ganji, Fariba

2015-05-01

In the present study, injectable hydrogels based on gum tragacanth-tyramine conjugate were prepared by enzymatic oxidation of tyramine radicals in the presence of hydrogen peroxide. Then, in vitro release of bovine serum albumin and insulin as model protein drugs from this polymeric network was investigated. Also, to improve the properties of this hydrogel, a blended hydrogel composed of tyramine-conjugated gelatin and tyramine-conjugated tragacanth was prepared. Experimental results showed that the gelation time ranged from 3 to 28 s depending on the polymer and enzyme concentrations. Results of morphological investigation of hydrogels indicated that the average pore size of hydrogels varied from 120 to 160 µm. Swelling degree of hydrogels and the rate of drug release decreased by increasing of hydrogen peroxide and polymer concentrations. The release profile of drug from hydrogels followed Higuchi and Fickian diffusion mechanism. Finally, it was shown that the swelling characteristics and drug release behavior of this polymeric network could be improved by blending it with tyramine-conjugated gelatin. © The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Scalable manufacturing of biomimetic moldable hydrogels for industrial applications

Science.gov (United States)

Yu, Anthony C.; Chen, Haoxuan; Chan, Doreen; Agmon, Gillie; Stapleton, Lyndsay M.; Sevit, Alex M.; Tibbitt, Mark W.; Acosta, Jesse D.; Zhang, Tony; Franzia, Paul W.; Langer, Robert; Appel, Eric A.

2016-12-01

Hydrogels are a class of soft material that is exploited in many, often completely disparate, industrial applications, on account of their unique and tunable properties. Advances in soft material design are yielding next-generation moldable hydrogels that address engineering criteria in several industrial settings such as complex viscosity modifiers, hydraulic or injection fluids, and sprayable carriers. Industrial implementation of these viscoelastic materials requires extreme volumes of material, upwards of several hundred million gallons per year. Here, we demonstrate a paradigm for the scalable fabrication of self-assembled moldable hydrogels using rationally engineered, biomimetic polymer-nanoparticle interactions. Cellulose derivatives are linked together by selective adsorption to silica nanoparticles via dynamic and multivalent interactions. We show that the self-assembly process for gel formation is easily scaled in a linear fashion from 0.5 mL to over 15 L without alteration of the mechanical properties of the resultant materials. The facile and scalable preparation of these materials leveraging self-assembly of inexpensive, renewable, and environmentally benign starting materials, coupled with the tunability of their properties, make them amenable to a range of industrial applications. In particular, we demonstrate their utility as injectable materials for pipeline maintenance and product recovery in industrial food manufacturing as well as their use as sprayable carriers for robust application of fire retardants in preventing wildland fires.

A hydrogel based nanosensor with an unprecedented broad sensitivity range for pH measurements in cellular compartments

DEFF Research Database (Denmark)

Zhang, M.; Søndergaard, Rikke Vicki; Ek, Pramod Kumar

2015-01-01

Optical pH nanosensors have been applied for monitoring intracellular pH in real-time for about two decades. However, the pH sensitivity range of most nanosensors is too narrow, and measurements that are on the borderline of this range may not be correct. Furthermore, ratiometric measurements...... of acidic intracellular pH (pH sensor, a fluorophore based nanosensor, with an unprecedented broad measurement range from pH 1.4 to 7.0. In this nanosensor, three p......H-sensitive fluorophores (difluoro-Oregon Green, Oregon Green 488, and fluorescein) and one pH-insensitive fluorophore (Alexa 568) were covalently incorporated into a nanoparticle hydrogel matrix. With this broad range quadruple-labelled nanosensor all physiological relevant pH levels in living cells can be measured...

Biocompatibility and intradiscal application of a thermoreversible celecoxib-loaded poly-N-isopropylacrylamide MgFe-layered double hydroxide hydrogel in a canine model.

Science.gov (United States)

Willems, Nicole; Yang, Hsiao-Yin; Langelaan, Marloes L P; Tellegen, Anna R; Grinwis, Guy C M; Kranenburg, Hendrik-Jan C; Riemers, Frank M; Plomp, Saskia G M; Craenmehr, Eric G M; Dhert, Wouter J A; Papen-Botterhuis, Nicole E; Meij, Björn P; Creemers, Laura B; Tryfonidou, Marianna A

2015-08-20

Chronic low back pain due to intervertebral disc (IVD) degeneration is associated with increased levels of inflammatory mediators. Current medical treatment consists of oral anti-inflammatory drugs to alleviate pain. In this study, the efficacy and safety of a novel thermoreversible poly-N-isopropylacrylamide MgFe-layered double hydroxide (pNIPAAM MgFe-LDH) hydrogel was evaluated for intradiscal controlled delivery of the selective cyclooxygenase (COX) 2 inhibitor and anti-inflammatory drug celecoxib (CXB). Degradation, release behavior, and the ability of a CXB-loaded pNIPAAM MgFe-LDH hydrogel to suppress prostaglandin E2 (PGE2) levels in a controlled manner in the presence of a proinflammatory stimulus (TNF-α) were evaluated in vitro. Biocompatibility was evaluated histologically after subcutaneous injection in mice. Safety of intradiscal application of the loaded and unloaded hydrogels was studied in a canine model of spontaneous mild IVD degeneration by histological, biomolecular, and biochemical evaluation. After the hydrogel was shown to be biocompatible and safe, an in vivo dose-response study was performed in order to determine safety and efficacy of the pNIPAAM MgFe-LDH hydrogel for intradiscal controlled delivery of CXB. CXB release correlated to hydrogel degradation in vitro. Furthermore, controlled release from CXB-loaded hydrogels was demonstrated to suppress PGE2 levels in the presence of TNF-α. The hydrogel was shown to exhibit a good biocompatibility upon subcutaneous injection in mice. Upon intradiscal injection in a canine model, the hydrogel exhibited excellent biocompatibility based on histological evaluation of the treated IVDs. Gene expression and biochemical analyses supported the finding that no substantial negative effects of the hydrogel were observed. Safety of application was further confirmed by the absence of clinical symptoms, IVD herniation or progression of degeneration. Controlled release of CXB resulted in a nonsignificant

Application of hydrogel-coated microcantilevers as sensing elements for pH

International Nuclear Information System (INIS)

Gonska, Julian; Schelling, Christoph; Urban, Gerald

2009-01-01

This note reports on cantilever-based sensor elements coated with a hydrogel. The hydrogel responds with a volume change on varying the pH value of surrounding liquids. The change in volume leads to a static deflection of the cantilevers, which is detected using integrated piezoresistors. To increase deflection sensitivity of the sensor elements, sub-micron, multilayered cantilevers consisting of polycrystalline silicon and silicon oxide are used. A new cantilever design is developed, which decreases the cantilever sensitivity to in situ stresses and thermal bimorph effects. A theoretical model for the sensor elements is introduced providing the output signal of multiple cantilevers connected in a full Wheatstone bridge. Measurements of deflection sensitivity prove the theoretical model. Finally, the cantilevers are coated with a 2-hydroxyethyl methacrylate and 2-(dimethylamino) ethyl methacrylate copolymer-based hydrogel, and changes in the pH value from pH 4 to pH 10 are measured. (technical note)

Transdermal thiol-acrylate polyethylene glycol hydrogel synthesis using near infrared light

Science.gov (United States)

Chung, Solchan; Lee, Hwangjae; Kim, Hyung-Seok; Kim, Min-Gon; Lee, Luke P.; Lee, Jae Young

2016-07-01

Light-induced polymerization has been widely applied for hydrogel synthesis, which conventionally involves the use of ultraviolet or visible light to activate a photoinitiator for polymerization. However, with these light sources, transdermal gelation is not efficient and feasible due to their substantial interactions with biological systems, and thus a high power is required. In this study, we used biocompatible and tissue-penetrating near infrared (NIR) light to remotely trigger a thiol-acrylate reaction for efficient in vivo gelation with good controllability. Our gelation system includes gold nanorods as a photothermal agent, a thermal initiator, diacrylate polyethylene glycol (PEG), and thiolated PEG. Irradiation with a low-power NIR laser (0.3 W cm-2) could induce gelation via a mixed-mode reaction with a small increase in temperature (~5 °C) under the optimized conditions. We also achieved successful transdermal gelation via the NIR-assisted photothermal thiol-acryl reactions. This new type of NIR-assisted thiol-acrylate polymerization provides new opportunities for in situ hydrogel formation for injectable hydrogels and delivery of drugs/cells for various biomedical applications.Light-induced polymerization has been widely applied for hydrogel synthesis, which conventionally involves the use of ultraviolet or visible light to activate a photoinitiator for polymerization. However, with these light sources, transdermal gelation is not efficient and feasible due to their substantial interactions with biological systems, and thus a high power is required. In this study, we used biocompatible and tissue-penetrating near infrared (NIR) light to remotely trigger a thiol-acrylate reaction for efficient in vivo gelation with good controllability. Our gelation system includes gold nanorods as a photothermal agent, a thermal initiator, diacrylate polyethylene glycol (PEG), and thiolated PEG. Irradiation with a low-power NIR laser (0.3 W cm-2) could induce gelation

Radiation synthesis of superabsorbent CMC based hydrogels for agriculture applications

International Nuclear Information System (INIS)

Raafat, Amany I.; Eid, Mona; El-Arnaouty, Magda B.

2012-01-01

A series of superabsorbent hydrogel based on carboxymethylcellulose (CMC) and polyvinylpyrrolidone (PVP) crosslinked with gamma irradiation have been proposed for agriculture application. The effect of preparation conditions such as feed solution composition and absorbed irradiation dose on the gelation and swelling degree was evaluated. The structure and the morphology of the superabsorbent CMC/PVP hydrogel were characterized using Fourier transform infrared spectroscopy technique (FTIR), and scanning electron microscope (SEM). Effect of ionic strength and cationic and anionic kinds on the swelling behavior of the obtained hydrogel was investigated. Urea as an agrochemical model was loaded onto the obtained hydrogel to provide nitrogen (N) nutrients. The water retention capability and the urea release behavior of the CMC/PVP hydrogels were investigated. It was found that, the obtained CMC/PVP hydrogels have good swelling degree that greatly affected by its composition and absorbed dose. The swelling was also extremely sensitive to the ionic strength and cationic kind. Owing to its considerable slow urea release, good water retention capacity, being economical, and environment-friendly, it might be useful for its application in agriculture field.

Radiation synthesis of superabsorbent CMC based hydrogels for agriculture applications

Science.gov (United States)

Raafat, Amany I.; Eid, Mona; El-Arnaouty, Magda B.

2012-07-01

A series of superabsorbent hydrogel based on carboxymethylcellulose (CMC) and polyvinylpyrrolidone (PVP) crosslinked with gamma irradiation have been proposed for agriculture application. The effect of preparation conditions such as feed solution composition and absorbed irradiation dose on the gelation and swelling degree was evaluated. The structure and the morphology of the superabsorbent CMC/PVP hydrogel were characterized using Fourier transform infrared spectroscopy technique (FTIR), and scanning electron microscope (SEM). Effect of ionic strength and cationic and anionic kinds on the swelling behavior of the obtained hydrogel was investigated. Urea as an agrochemical model was loaded onto the obtained hydrogel to provide nitrogen (N) nutrients. The water retention capability and the urea release behavior of the CMC/PVP hydrogels were investigated. It was found that, the obtained CMC/PVP hydrogels have good swelling degree that greatly affected by its composition and absorbed dose. The swelling was also extremely sensitive to the ionic strength and cationic kind. Owing to its considerable slow urea release, good water retention capacity, being economical, and environment-friendly, it might be useful for its application in agriculture field.

Radiation synthesis of superabsorbent CMC based hydrogels for agriculture applications

Energy Technology Data Exchange (ETDEWEB)

Raafat, Amany I., E-mail: ismaelraafat_a@hotmail.com [Polymer Chemistry Department, National Center for Radiation Research and Technology, P.O. Box 29, Nasr City, Cairo (Egypt); Eid, Mona; El-Arnaouty, Magda B. [Polymer Chemistry Department, National Center for Radiation Research and Technology, P.O. Box 29, Nasr City, Cairo (Egypt)

2012-07-15

A series of superabsorbent hydrogel based on carboxymethylcellulose (CMC) and polyvinylpyrrolidone (PVP) crosslinked with gamma irradiation have been proposed for agriculture application. The effect of preparation conditions such as feed solution composition and absorbed irradiation dose on the gelation and swelling degree was evaluated. The structure and the morphology of the superabsorbent CMC/PVP hydrogel were characterized using Fourier transform infrared spectroscopy technique (FTIR), and scanning electron microscope (SEM). Effect of ionic strength and cationic and anionic kinds on the swelling behavior of the obtained hydrogel was investigated. Urea as an agrochemical model was loaded onto the obtained hydrogel to provide nitrogen (N) nutrients. The water retention capability and the urea release behavior of the CMC/PVP hydrogels were investigated. It was found that, the obtained CMC/PVP hydrogels have good swelling degree that greatly affected by its composition and absorbed dose. The swelling was also extremely sensitive to the ionic strength and cationic kind. Owing to its considerable slow urea release, good water retention capacity, being economical, and environment-friendly, it might be useful for its application in agriculture field.

Thermoresponsive Polymers and Inverse Opal Hydrogels for the Detection of Diols.

Science.gov (United States)

Couturier, Jean-Philippe; Wischerhoff, Erik; Bernin, Robert; Hettrich, Cornelia; Koetz, Joachim; Sütterlin, Martin; Tiersch, Brigitte; Laschewsky, André

2016-05-03

Responsive inverse opal hydrogels functionalized by boroxole moieties were synthesized and explored as sensor platforms for various low molar mass as well as polymeric diols and polyols, including saccharides, glycopolymers and catechols, by exploiting the diol induced modulation of their structural color. The underlying thermoresponsive water-soluble copolymers and hydrogels exhibit a coil-to-globule or volume phase transition, respectively, of the LCST-type. They were prepared from oligoethylene oxide methacrylate (macro)monomers and functionalized via copolymerization to bear benzoboroxole moieties. The resulting copolymers represent weak polyacids, which can bind specifically to diols within an appropriate pH window. Due to the resulting modulation of the overall hydrophilicity of the systems and the consequent shift of their phase transition temperature, the usefulness of such systems for indicating the presence of catechols, saccharides, and glycopolymers was studied, exploiting the diol/polyol induced shifts of the soluble polymers' cloud point, or the induced changes of the hydrogels' swelling. In particular, the increased acidity of benzoboroxoles compared to standard phenylboronic acids allowed performing the studies in PBS buffer (phosphate buffered saline) at the physiologically relevant pH of 7.4. The inverse opals constructed of these thermo- and analyte-responsive hydrogels enabled following the binding of specific diols by the induced shift of the optical stop band. Their highly porous structure enabled the facile and specific optical detection of not only low molar mass but also of high molar mass diol/polyol analytes such as glycopolymers. Accordingly, such thermoresponsive inverse opal systems functionalized with recognition units represent attractive and promising platforms for the facile sensing of even rather big analytes by simple optical means, or even by the bare eye.

Hydrogel based tissue mimicking phantom for in-vitro ultrasound contrast agents studies.

Science.gov (United States)

Demitri, Christian; Sannino, Alessandro; Conversano, Francesco; Casciaro, Sergio; Distante, Alessandro; Maffezzoli, Alfonso

2008-11-01

Ultrasound medical imaging (UMI) is the most widely used image analysis technique, and often requires advanced in-vitro set up to perform morphological and functional investigations. These studies are based on contrast properties both related to tissue structure and injectable contrast agents (CA). In this work, we present a three-dimensional structure composed of two different hydrogels reassembly the microvascular network of a human tissue. This phantom was particularly suitable for the echocontrastographic measurements in human microvascular system. This phantom has been characterized to present the acoustic properties of an animal liver, that is, acoustic impedance (Z) and attenuation coefficient (AC), in UMI signal analysis in particular; the two different hydrogels have been selected to simulate the target organ and the acoustic properties of the vascular system. The two hydrogels were prepared starting from cellulose derivatives to simulating the target organ parenchyma and using a PEG-diacrylate to reproduce the vascular system. Moreover, harmonic analysis was performed on the hydrogel mimicking the liver parenchyma hydrogel to evaluate the ultrasound (US) distortion during echographic measurement. The phantom was employed in the characterization of an experimental US CA. Perfect agreement was found when comparing the hydrogel acoustical properties materials with the corresponding living reference tissues (i.e., vascular and parenchimal tissue).

Effects of local application of methylprednisolone delivered by the C/GP-hydrogel on the recovery of facial nerves.

Science.gov (United States)

Chao, Xiuhua; Fan, Zhaomin; Han, Yuechen; Wang, Yan; Li, Jianfeng; Chai, Renjie; Xu, Lei; Wang, Haibo

2015-01-01

Local administration of MP delivered by the C/GP-MP-hydrogel can improve the recovery of facial nerve following crush injury. The findings suggested that locally injected MP delivered by C/GP-hydrogel might be a promising treatment for facial nerve damage. In this study, the aim is to assess the effectiveness of locally administrating methylprednisolone(MP) loaded by chitosan-β-glycerophosphate hydrogel (C/GP-hydrogel) on the regeneration of facial nerve crush injury. After the crush of left facial nerves, Wistar rats were randomly divided into four different groups. Then, four different therapies were used to treat the damaged facial nerves. At the 1(st), 2(nd), 3(rd), and 4(th) week after injury, the functional recovery of facial nerves and the morphological changes of facial nerves were assessed. The expression of growth associated protein-43 (GAP-43) protein in the facial nucleus were also evaluated. Locally injected MP delivered by C/GP-hydrogel effectively accelerated the facial functional recovery. In addition, the regenerated facial nerves in the C/GP-MP group were more mature than those in the other groups. The expression of GAP-43 protein was also improved by the MP, especially in the C/GP-MP group.

Synthesis and application of intelligent hydrogels

International Nuclear Information System (INIS)

Kaetsu, I.; Uchida, K.; Sutani, K.; Nakayama, H.; Tamori, A.

2000-01-01

The authors have studied synthesis and application of stimule-sensitive and responsive hydrogels. In this report, two kinds of investigations were carried out on the intelligent hydrogels and the applications with radiation techniques. 1. Synthesis of temperature responsive sol-gel transition polymer and the application to drug delivery systems. Polysopropyl acrylamide is a typical temperature responsive polymers and the copolymers show broad variation of LCST (sol-gel transition temperature). The various copolymers of isopropyl acrylamide were synthesized by UV or radiation. 2. Surface curing of pH and electric field responsive hydrogel and the application to drug delivery systems. Electrolyte monomers such as acrylic acid was coated on the surface of polymer membrane (porous or non-porous) including drugs, and cured by UV or radiation various enzymes were immobilized in the coating layer in many cases. The product showed pH, electro-field and substrate responsive releases of model drug under on-off switching of environmental conditions. (J.P.N.)

Synthesis and application of intelligent hydrogels

Energy Technology Data Exchange (ETDEWEB)

Kaetsu, I.; Uchida, K.; Sutani, K.; Nakayama, H.; Tamori, A. [Kinki Univ., Higashi-Osaka, Osaka (Japan). Faculty of Science and Technology

2000-03-01

The authors have studied synthesis and application of stimule-sensitive and responsive hydrogels. In this report, two kinds of investigations were carried out on the intelligent hydrogels and the applications with radiation techniques. 1. Synthesis of temperature responsive sol-gel transition polymer and the application to drug delivery systems. Polysopropyl acrylamide is a typical temperature responsive polymers and the copolymers show broad variation of LCST (sol-gel transition temperature). The various copolymers of isopropyl acrylamide were synthesized by UV or radiation. 2. Surface curing of pH and electric field responsive hydrogel and the application to drug delivery systems. Electrolyte monomers such as acrylic acid was coated on the surface of polymer membrane (porous or non-porous) including drugs, and cured by UV or radiation various enzymes were immobilized in the coating layer in many cases. The product showed pH, electro-field and substrate responsive releases of model drug under on-off switching of environmental conditions. (J.P.N.)

Thermo-economic analysis of a solid oxide fuel cell and steam injected gas turbine plant integrated with woodchips gasification

DEFF Research Database (Denmark)

Mazzucco, Andrea; Rokni, Masoud

2014-01-01

cost on the generation cost is also presented. In order to discuss the investment cost, an economic analysis has been carried out and main parameters such as Net Present Value (NPV), internal rate of return (IRR) and Time of Return of Investment (TIR) are calculated and discussed.......% respectively which are significantly greater than conventional 10 MWe plants fed by biomass. Thermo-economic analysis provides an average cost of electricity for best performing layouts close to 6.4 and 9.4 c€/kWe which is competitive within the market. A sensitivity analysis of the influence of SOFC stack...

Multi-scale modeling of photopolymerization for medical hydrogel-implant design

Science.gov (United States)

Schmocker, Andreas; Khoushabi, Azadeh; Farahi, Salma; Pioletti, Dominique; Bourban, Pierre-Etienne; Manson, Jan A.; Moser, Christophe

2013-02-01

We report on the modeling of a photopolymerizable hydrogel and its application as a replacement of the interior of the intervertebral disc (so called Nucleus Pulposus). The hydrogel is initially injected in its liquid form and then photopolymerized via a small catheter. Therefore, also the light necessary for the photopolymerization is constrained to a small light guide to keep the surgical procedure as minimally invasive as possible. Hence, the hydrogel is photopolymerized inside. For applications with restricted physical access and illumination time, such as an Nucleus Pulposus replacement, photopolymerization of volumes with a large volume/illumination-area ratio becomes highly challenging. During polymerization, the material's absorption and scattering coefficients change and directly influence local polymerization rates. By understanding and controlling such polymerization patterns, local material properties can be engineered (e.g. elastic modulus, swelling ratio), to match the set of mechanical requirements for the implant. Thus, it is essential to better understand and model photopolymerization reactions. Experiments were conducted by polymerizing a hydrogel in a column-like volume using an optical fiber for light delivery. Quantitative scattering and absorption values as well as monomer conversion rates of the hydrogel sample were validated using a newly established Monte Carlo model for photopolymerization. The results were used to study and predict 3D polymerization patterns for different illumination configurations. In particular, we show an example of a lumbar intervertebral disc replacement where the jelly core of the intervertebral disc (Nucleus Pulposus) is replaced by an in situ photopolymerized hydrogel. The results provide insights for the development of novel endoscopic light-scattering polymerization probes paving the way for a new generation of implantable hydrogels.

Hydrogel based occlusion systems

NARCIS (Netherlands)

Stam, F.A.; Jackson, N.; Dubruel, P.; Adesanya, K.; Embrechts, A.; Mendes, E.; Neves, H.P.; Herijgers, P.; Verbrugghe, Y.; Shacham, Y.; Engel, L.; Krylov, V.

2013-01-01

A hydrogel based occlusion system, a method for occluding vessels, appendages or aneurysms, and a method for hydrogel synthesis are disclosed. The hydrogel based occlusion system includes a hydrogel having a shrunken and a swollen state and a delivery tool configured to deliver the hydrogel to a

Near-Infrared Light-Sensitive Polyvinyl Alcohol Hydrogel Photoresist for Spatiotemporal Control of Cell-Instructive 3D Microenvironments.

Science.gov (United States)

Qin, Xiao-Hua; Wang, Xiaopu; Rottmar, Markus; Nelson, Bradley J; Maniura-Weber, Katharina

2018-03-01

Advanced hydrogel systems that allow precise control of cells and their 3D microenvironments are needed in tissue engineering, disease modeling, and drug screening. Multiphoton lithography (MPL) allows true 3D microfabrication of complex objects, but its biological application requires a cell-compatible hydrogel resist that is sufficiently photosensitive, cell-degradable, and permissive to support 3D cell growth. Here, an extremely photosensitive cell-responsive hydrogel composed of peptide-crosslinked polyvinyl alcohol (PVA) is designed to expand the biological applications of MPL. PVA hydrogels are formed rapidly by ultraviolet light within 1 min in the presence of cells, providing fully synthetic matrices that are instructive for cell-matrix remodeling, multicellular morphogenesis, and protease-mediated cell invasion. By focusing a multiphoton laser into a cell-laden PVA hydrogel, cell-instructive extracellular cues are site-specifically attached to the PVA matrix. Cell invasion is thus precisely guided in 3D with micrometer-scale spatial resolution. This robust hydrogel enables, for the first time, ultrafast MPL of cell-responsive synthetic matrices at writing speeds up to 50 mm s -1 . This approach should enable facile photochemical construction and manipulation of 3D cellular microenvironments with unprecedented flexibility and precision. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamic behavior of acrylic acid clusters as quasi-mobile nodes in a model of hydrogel network

Science.gov (United States)

Zidek, Jan; Milchev, Andrey; Vilgis, Thomas A.

2012-12-01

Using a molecular dynamics simulation, we study the thermo-mechanical behavior of a model hydrogel subject to deformation and change in temperature. The model is found to describe qualitatively poly-lactide-glycolide hydrogels in which acrylic acid (AA)-groups are believed to play the role of quasi-mobile nodes in the formation of a network. From our extensive analysis of the structure, formation, and disintegration of the AA-groups, we are able to elucidate the relationship between structure and viscous-elastic behavior of the model hydrogel. Thus, in qualitative agreement with observations, we find a softening of the mechanical response at large deformations, which is enhanced by growing temperature. Several observables as the non-affinity parameter A and the network rearrangement parameter V indicate the existence of a (temperature-dependent) threshold degree of deformation beyond which the quasi-elastic response of the model system turns over into plastic (ductile) one. The critical stretching when the affinity of the deformation is lost can be clearly located in terms of A and V as well as by analysis of the energy density of the system. The observed stress-strain relationship matches that of known experimental systems.

DNA Hydrogel with Tunable pH-Responsive Properties Produced by Rolling Circle Amplification.

Science.gov (United States)

Xu, Wanlin; Huang, Yishun; Zhao, Haoran; Li, Pan; Liu, Guoyuan; Li, Jing; Zhu, Chengshen; Tian, Leilei

2017-12-22

Recently, smart DNA hydrogels, which are generally formed by the self-assembly of oligonucleotides or through the cross-linking of oligonucleotide-polymer hybrids, have attracted tremendous attention. However, the difficulties of fabricating DNA hydrogels limit their practical applications. We report herein a novel method for producing pH-responsive hydrogels by rolling circle amplification (RCA). In this method, pH-sensitive cross-linking sites were introduced into the polymeric DNA chains during DNA synthesis. As the DNA sequence can be precisely defined by its template, the properties of such hydrogels can be finely tuned in a very facile way through template design. We have investigated the process of hydrogel formation and pH-responsiveness to provide rationales for functional hydrogel design based on the RCA reaction. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and characterization of a novel cationic hydrogel base on salecan-g-PMAPTAC.

Science.gov (United States)

Wei, Wei; Qi, Xiaoliang; Li, Junjian; Zhong, Yin; Zuo, Gancheng; Pan, Xihao; Su, Ting; Zhang, Jianfa; Dong, Wei

2017-08-01

Salecan is a biological macromolecular and biocompatible polysaccharide that has been investigated for recent years. Herein, we report a novel cationic hydrogel fabricated by graft-polymerizing 3-(methacryloylamino)propyl-trimethylammonium chloride (MAPTAC) onto salecan chains. The obtained hydrogels were transparent, solid-elastic, macro-porous, ion-sensitive, and non-cytotoxic. The swelling ratios increased with salecan content, while mechanical strength does the opposite. Moreover, drug delivery test was studied as a potential application. Diclofenac sodium (DS) and insulin were selected as model drugs. Interestingly, in drug loading process, DS molecules exhibited highly affinity to these cationic hydrogels. Almost all the DS molecules in loading solution were absorbed and spread into the hydrogel. For drug release profiles, insulin-loaded hydrogel showed an initial rapid release and a sustained release. As a comparison, DS-loaded hydrogel exhibited a more sustained release profile. Results suggested salecan-g-PMAPTAC hydrogel could be a good candidate for anionic drug loading and delivery. Copyright © 2017 Elsevier B.V. All rights reserved.

Carbon nanotube-incorporated collagen hydrogels improve cell alignment and the performance of cardiac constructs

Science.gov (United States)

Sun, Hongyu; Zhou, Jing; Huang, Zhu; Qu, Linlin; Lin, Ning; Liang, Chengxiao; Dai, Ruiwu; Tang, Lijun; Tian, Fuzhou

2017-01-01

Carbon nanotubes (CNTs) provide an essential 2-D microenvironment for cardiomyocyte growth and function. However, it remains to be elucidated whether CNT nanostructures can promote cell–cell integrity and facilitate the formation of functional tissues in 3-D hydrogels. Here, single-walled CNTs were incorporated into collagen hydrogels to fabricate (CNT/Col) hydrogels, which improved mechanical and electrical properties. The incorporation of CNTs (up to 1 wt%) exhibited no toxicity to cardiomyocytes and enhanced cell adhesion and elongation. Through the use of immunohistochemical staining, transmission electron microscopy, and intracellular calcium-transient measurement, the incorporation of CNTs was found to improve cell alignment and assembly remarkably, which led to the formation of engineered cardiac tissues with stronger contraction potential. Importantly, cardiac tissues based on CNT/Col hydrogels were noted to have better functionality. Collectively, the incorporation of CNTs into the Col hydrogels improved cell alignment and the performance of cardiac constructs. Our study suggests that CNT/Col hydrogels offer a promising tissue scaffold for cardiac constructs, and might serve as injectable biomaterials to deliver cell or drug molecules for cardiac regeneration following myocardial infarction in the near future. PMID:28450785

Temperature responsive hydrogel magnetic nanocomposites for hyperthermia and metal extraction applications

Energy Technology Data Exchange (ETDEWEB)

Reddy, N. Narayana, E-mail: nagireddynarayana@gmail.com [Center for Advanced Biomaterials for Healthcare, Istituto Italiano di Tecnologia@CRIB, Largo Barsanti e Matteucci 53, 80125 Napoli (Italy); Ravindra, S. [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1709 (South Africa); Reddy, N. Madhava [Department of Environmental Science, Gates Institute of Technology, NH-7, Gooty, Anantapuram, Andhra Pradesh (India); Rajinikanth, V. [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1709 (South Africa); Raju, K. Mohana [Synthetic Polymer Laboratory, Department of Polymer Science & Technology, S.K. University, Anantapuram, Andhra Pradesh (India); Vallabhapurapu, Vijaya Srinivasu [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1709 (South Africa)

2015-11-15

The present work deals with the development of temperature and magnetic responsive hydrogel networks based on poly (N-isopropylacrylamide)/acrylamido propane sulfonic acid. The hydrogel matrices are synthesized by polymerizing N-isopropylacrylamide (NIPAM) monomer in the presence of acrylamido propane sulphonicacid (AMPS) using a cross-linker (N,N-methylenebisacrylamide, MBA) and redox initiating system [ammonium persulphate (APS)/tetramethylethylenediamine (TMEDA)]. The magnetic nanoparticles are generated throughout the hydrogel networks using in situ method by incorporating iron ions and subsequent treatment with ammonia. A series of hydrogel-magnetic nanocomposites (HGMNC) are developed by varying AMPS composition. The synthesized hydrogel magnetic nanocomposites (HGMNC) are characterized by using Fourier Transform Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), Thermal Analyses and Electron Microscopy analysis (Scanning and Transmission Electron Microscope). The metal extraction capacities of the prepared hydrogel (HG) and hydrogel magnetic nanocomposites (HGMNC) were studied at different temperatures. The results suggest that HGMNCs have higher extraction capacity compared to HG and HG loaded iron ions. This data also reveals that the extraction of metals by hydrogel magnetic nanocomposites (HGMNCs) is higher at higher temperatures than room temperature. The prepared HGMNCs are also subjected to hyperthermia (cancer therapy) studies. - Highlights: • We have developed temperature responsive hydrogel magnetic nanocomposites. • Addition of AMPS monomer to this magnetic hydrogel enhances the temperature sensitivity to 40–43 °C. • Similarly the sulfonic groups present in the AMPS units enhances the swelling ratio of magnetic hydrogels. • AMPS acts as good stabilizing agent for nanoparticles in the magnetic nanogel.

Temperature responsive hydrogel magnetic nanocomposites for hyperthermia and metal extraction applications

International Nuclear Information System (INIS)

Reddy, N. Narayana; Ravindra, S.; Reddy, N. Madhava; Rajinikanth, V.; Raju, K. Mohana; Vallabhapurapu, Vijaya Srinivasu

2015-01-01

The present work deals with the development of temperature and magnetic responsive hydrogel networks based on poly (N-isopropylacrylamide)/acrylamido propane sulfonic acid. The hydrogel matrices are synthesized by polymerizing N-isopropylacrylamide (NIPAM) monomer in the presence of acrylamido propane sulphonicacid (AMPS) using a cross-linker (N,N-methylenebisacrylamide, MBA) and redox initiating system [ammonium persulphate (APS)/tetramethylethylenediamine (TMEDA)]. The magnetic nanoparticles are generated throughout the hydrogel networks using in situ method by incorporating iron ions and subsequent treatment with ammonia. A series of hydrogel-magnetic nanocomposites (HGMNC) are developed by varying AMPS composition. The synthesized hydrogel magnetic nanocomposites (HGMNC) are characterized by using Fourier Transform Infrared (FTIR) Spectroscopy, X-ray diffraction (XRD), Thermal Analyses and Electron Microscopy analysis (Scanning and Transmission Electron Microscope). The metal extraction capacities of the prepared hydrogel (HG) and hydrogel magnetic nanocomposites (HGMNC) were studied at different temperatures. The results suggest that HGMNCs have higher extraction capacity compared to HG and HG loaded iron ions. This data also reveals that the extraction of metals by hydrogel magnetic nanocomposites (HGMNCs) is higher at higher temperatures than room temperature. The prepared HGMNCs are also subjected to hyperthermia (cancer therapy) studies. - Highlights: • We have developed temperature responsive hydrogel magnetic nanocomposites. • Addition of AMPS monomer to this magnetic hydrogel enhances the temperature sensitivity to 40–43 °C. • Similarly the sulfonic groups present in the AMPS units enhances the swelling ratio of magnetic hydrogels. • AMPS acts as good stabilizing agent for nanoparticles in the magnetic nanogel

Thermo Wigner operator in thermo field dynamics: its introduction and application

International Nuclear Information System (INIS)

Fan Hongyi; Jiang Nianquan

2008-01-01

Because in thermo-field dynamics (TFD) the thermo-operator has a neat expression in the thermo-entangled state representation, we need to introduce the thermo-Wigner operator (THWO) in the same representation. We derive the THWO in a direct way, which brings much conveniece to calculating the Wigner functions of thermo states in TFD. We also discuss the condition for existence of a wavefunction corresponding to a given Wigner function in the context of TFD by using the explicit form of the THWO.

Hydrogels for central nervous system therapeutic strategies.

Science.gov (United States)

Russo, Teresa; Tunesi, Marta; Giordano, Carmen; Gloria, Antonio; Ambrosio, Luigi

2015-12-01

The central nervous system shows a limited regenerative capacity, and injuries or diseases, such as those in the spinal, brain and retina, are a great problem since current therapies seem to be unable to achieve good results in terms of significant functional recovery. Different promising therapies have been suggested, the aim being to restore at least some of the lost functions. The current review deals with the use of hydrogels in developing advanced devices for central nervous system therapeutic strategies. Several approaches, involving cell-based therapy, delivery of bioactive molecules and nanoparticle-based drug delivery, will be first reviewed. Finally, some examples of injectable hydrogels for the delivery of bioactive molecules in central nervous system will be reported, and the key features as well as the basic principles in designing multifunctional devices will be described. © IMechE 2015.

Intradiscal application of a PCLA-PEG-PCLA hydrogel loaded with celecoxib for the treatment of back pain in canines: What's in it for humans?

Science.gov (United States)

Tellegen, Anna R; Willems, Nicole; Beukers, Martijn; Grinwis, Guy C M; Plomp, Saskia G M; Bos, Clemens; van Dijk, Maarten; de Leeuw, Mike; Creemers, Laura B; Tryfonidou, Marianna A; Meij, Björn P

2018-03-01

Chronic low back pain is a common clinical problem in both the human and canine population. Current pharmaceutical treatment often consists of oral anti-inflammatory drugs to alleviate pain. Novel treatments for degenerative disc disease focus on local application of sustained released drug formulations. The aim of this study was to determine safety and feasibility of intradiscal application of a poly(ε-caprolactone-co-lactide)-b-poly(ethylene glycol)-bpoly(ε-caprolactone-co-lactide) PCLA-PEG-PCLA hydrogel releasing celecoxib, a COX-2 inhibitor. Biocompatibility was evaluated after subcutaneous injection in mice, and safety of intradiscal injection of the hydrogel was evaluated in experimental dogs with early spontaneous intervertebral disc (IVD) degeneration. COX-2 expression was increased in IVD samples surgically obtained from canine patients, indicating a role of COX-2 in clinical IVD disease. Ten client-owned dogs with chronic low back pain related to IVD degeneration received an intradiscal injection with the celecoxib-loaded hydrogel. None of the dogs showed adverse reactions after intradiscal injection. The hydrogel did not influence magnetic resonance imaging signal at long-term follow-up. Clinical improvement was achieved by reduction of back pain in 9 of 10 dogs, as was shown by clinical examination and owner questionnaires. In 3 of 10 dogs, back pain recurred after 3 months. This study showed the safety and effectiveness of intradiscal injections in vivo with a thermoresponsive PCLA-PEG-PCLA hydrogel loaded with celecoxib. In this set-up, the dog can be used as a model for the development of novel treatment modalities in both canine and human patients with chronic low back pain. Copyright © 2017 John Wiley & Sons, Ltd.

Junction temperature measurements via thermo-sensitive electrical parameters and their application to condition monitoring and active thermal control of power converters

DEFF Research Database (Denmark)

Baker, Nick; Liserre, Marco; Dupont, L.

2013-01-01

implementation of active thermal control to reduce losses and increase lifetime can be performed given an accurate knowledge of temperature. Temperature measurements via thermo-sensitive electrical parameters (TSEP) are one way to carry out immediate temperature readings on fully packaged devices. However...... scale implementation of these methods are discussed. Their potential use in the aforementioned goals in condition monitoring and active thermal control is also described....

Fluorescent nanocellulosic hydrogels based on graphene quantum dots for sensing laccase

International Nuclear Information System (INIS)

Ruiz-Palomero, Celia; Benítez-Martínez, Sandra; Soriano, M. Laura; Valcárcel, Miguel

2017-01-01

A novel low-cost fluorimetric platform based on sulfur, nitrogen-codoped graphene quantum dots immersed into nanocellulosic hydrogels is designed and applied in detecting the laccase enzyme. Although most of methods for detecting laccase are based on their catalytic activity, which is strongly dependent on environmental parameters, we report a sensitive and selective method based on the fluorescence response of hydrogels containing graphene quantum dots (GQDs) acting as luminophore towards laccase. The easily-prepared gel matrix not only improves the fluorescence signal of GQDs by avoiding their self-quenching but also stabilizes their fluorescence signal and improves their sensitivity towards laccase. Noncovalent interactions between the sensor and the analyte are believed to be causing this significant quenching without peak-shifts of GQD fluorescence via energy transfer. The selective extraction of laccase was proved in different shampoos as complex matrices achieving a detection limit of 0.048 U mL −1 and recoveries of 86.2–94.1%. As the unusual properties of nanocellulose and GQDs, the fluorescent sensor is simple, eco-friendly and cost-efficient. This straightforward strategy is able to detect and stabilize laccase, being an added-value for storage and recycling enzymes. - Highlights: • Fluorescent hydrogels were constructed by combining nanocellulose and graphene quantum dots. • The resulting hydrogels exhibited fluorescence quenching in presence of laccase. • Equilibrium in the optical signal of S,N-graphene quantum dots in presence of laccase was achieved faster within hydrogels. • The proposed method to determine laccase using fluorescent hydrogels was successfully applied in shampoo.

Imaging findings of breast augmentation with injected hydrophilic polyacrylamide gel: Patient reports and literature review

International Nuclear Information System (INIS)

Khedher, Najoua Ben; David, Julie; Trop, Isabelle; Drouin, Suzanne; Peloquin, Laurence; Lalonde, Lucie

2011-01-01

Hydrophilic polyacrylamide gel (PAAG) is a nonresorbable soft tissue filler that has been used as implant material for breast augmentation in some countries, particularly from the Asian continent. Many complications associated with hydrogel use have been reported in the clinical literature including inflammation, persistent mastodynia, formation of multiple lumps, poor cosmetic results, glandular atrophy, and significant spread of hydrogel into the surrounding tissue. Data on long-term toxicity is currently unavailable. The radiologic features of PAAG injection mammoplasty frequently constitute a diagnostic challenge for radiologists. Indeed, the imaging appearances of uncomplicated PAAG implants may mimic conventional implants on mammography, sonography and MRI, with some distinguishing features. The location and local spread of the injected PAAG, and the eventual detection of local inflammation, are best evaluated by ultrasonography and especially MRI, considered the most sensitive technique for assessment of PAAG mammoplasty. MRI clearly depicts the volume and the distribution of gel within the breast; contrast medium enhancement allows delineation of areas of inflammation and infection. It is important to be familiar with the spectrum of imaging findings in order to make an accurate diagnosis and offer proper management. This paper aims to review the normal and abnormal mammographic, sonographic, and MR imaging characteristics of PAAG augmentation mammoplasty through presented patient reviews of three women having undergone direct PAAG injection.

Imaging findings of breast augmentation with injected hydrophilic polyacrylamide gel: Patient reports and literature review

Energy Technology Data Exchange (ETDEWEB)

Khedher, Najoua Ben, E-mail: nbenkhedher@gmail.com [Centre d' Investigation et de Recherche Diagnostique des maladies du sein (CRID), Centre hospitalier de l' Universite de Montreal, Hotel-Dieu, 3840 rue Saint-Urbain, Montreal (Quebec), H2W 1T8 (Canada); David, Julie, E-mail: jdavid@vl.videotron.ca [Centre d' Investigation et de Recherche Diagnostique des maladies du sein (CRID), Centre hospitalier de l' Universite de Montreal, Hotel-Dieu, 3840 rue Saint-Urbain, Montreal (Quebec), H2W 1T8 (Canada); Trop, Isabelle, E-mail: itrop@yahoo.com [Centre d' Investigation et de Recherche Diagnostique des maladies du sein (CRID), Centre hospitalier de l' Universite de Montreal, Hotel-Dieu, 3840 rue Saint-Urbain, Montreal (Quebec), H2W 1T8 (Canada); Drouin, Suzanne, E-mail: suedrouin@sympatico.ca [Clinique Radiologique Leger et associees, 1851 rue Sherbrooke Est, Bureau 201, Montreal (Quebec), H2K 4L5 (Canada); Peloquin, Laurence, E-mail: laurence.peloquin@gmail.com [Centre d' Investigation et de Recherche Diagnostique des maladies du sein (CRID), Centre hospitalier de l' Universite de Montreal, Hotel-Dieu, 3840 rue Saint-Urbain, Montreal (Quebec), H2W 1T8 (Canada); Lalonde, Lucie, E-mail: lalucie@sympatico.ca [Centre d' Investigation et de Recherche Diagnostique des maladies du sein (CRID), Centre hospitalier de l' Universite de Montreal, Hotel-Dieu, 3840 rue Saint-Urbain, Montreal (Quebec), H2W 1T8 (Canada)

2011-04-15

Hydrophilic polyacrylamide gel (PAAG) is a nonresorbable soft tissue filler that has been used as implant material for breast augmentation in some countries, particularly from the Asian continent. Many complications associated with hydrogel use have been reported in the clinical literature including inflammation, persistent mastodynia, formation of multiple lumps, poor cosmetic results, glandular atrophy, and significant spread of hydrogel into the surrounding tissue. Data on long-term toxicity is currently unavailable. The radiologic features of PAAG injection mammoplasty frequently constitute a diagnostic challenge for radiologists. Indeed, the imaging appearances of uncomplicated PAAG implants may mimic conventional implants on mammography, sonography and MRI, with some distinguishing features. The location and local spread of the injected PAAG, and the eventual detection of local inflammation, are best evaluated by ultrasonography and especially MRI, considered the most sensitive technique for assessment of PAAG mammoplasty. MRI clearly depicts the volume and the distribution of gel within the breast; contrast medium enhancement allows delineation of areas of inflammation and infection. It is important to be familiar with the spectrum of imaging findings in order to make an accurate diagnosis and offer proper management. This paper aims to review the normal and abnormal mammographic, sonographic, and MR imaging characteristics of PAAG augmentation mammoplasty through presented patient reviews of three women having undergone direct PAAG injection.

Surface enhanced thermo lithography

KAUST Repository

Coluccio, Maria Laura

2017-01-13

We used electroless deposition to fabricate clusters of silver nanoparticles (NPs) on a silicon substrate. These clusters are plasmonics devices that induce giant electromagnetic (EM) field increments. When those EM field are absorbed by the metal NPs clusters generate, in turn, severe temperature increases. Here, we used the laser radiation of a conventional Raman set-up to transfer geometrical patterns from a template of metal NPs clusters into a layer of thermo sensitive Polyphthalaldehyde (PPA) polymer. Temperature profile on the devices depends on specific arrangements of silver nanoparticles. In plane temperature variations may be controlled with (i) high nano-meter spatial precision and (ii) single Kelvin temperature resolution on varying the shape, size and spacing of metal nanostructures. This scheme can be used to generate strongly localized heat amplifications for applications in nanotechnology, surface enhanced thermo-lithography (SETL), biology and medicine (for space resolved cell ablation and treatment), nano-chemistry.

Surface enhanced thermo lithography

KAUST Repository

Coluccio, Maria Laura; Alabastri, Alessandro; Bonanni, Simon; Majewska, Roksana; Dattoli, Elisabetta; Barberio, Marianna; Candeloro, Patrizio; Perozziello, Gerardo; Mollace, Vincenzo; Di Fabrizio, Enzo M.; Gentile, Francesco

2017-01-01

We used electroless deposition to fabricate clusters of silver nanoparticles (NPs) on a silicon substrate. These clusters are plasmonics devices that induce giant electromagnetic (EM) field increments. When those EM field are absorbed by the metal NPs clusters generate, in turn, severe temperature increases. Here, we used the laser radiation of a conventional Raman set-up to transfer geometrical patterns from a template of metal NPs clusters into a layer of thermo sensitive Polyphthalaldehyde (PPA) polymer. Temperature profile on the devices depends on specific arrangements of silver nanoparticles. In plane temperature variations may be controlled with (i) high nano-meter spatial precision and (ii) single Kelvin temperature resolution on varying the shape, size and spacing of metal nanostructures. This scheme can be used to generate strongly localized heat amplifications for applications in nanotechnology, surface enhanced thermo-lithography (SETL), biology and medicine (for space resolved cell ablation and treatment), nano-chemistry.

Prevention of filtering surgery failure by subconjunctival injection of a novel peptide hydrogel into rabbit eyes

Energy Technology Data Exchange (ETDEWEB)

Liang Liang [Department of Ophthalmology, The Central Hospital of Wuhan, Wuhan 430014 (China); Xu Xiaoding; Zhang Xianzheng [Key Laboratory of Biomedical Polymers of Ministry of Education and Department of Chemistry, Wuhan University, Wuhan 430072 (China); Feng Mei; Peng Chong; Jiang Fagang [Department of Ophthalmology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China)

2010-08-01

A novel biocompatible hydrogel was prepared based on the supramolecular self-assembly of a peptide containing a bioactive RGD (arginine-glycine-aspartic acid) sequence and a hydrophobic N-fluorenyl-9-methoxycarbonyl (FMOC) tail. When the self-assembled peptide hydrogel was administered after the filtering surgery of rabbit eyes, the level of connective tissue growth factor (CTGF) mRNA as well as the mean intraocular pressure (IOP) was significantly lower than that of the control eyes during the 21 postoperative days. The filtration bleb and ultrasound biomicroscopy (UBM) images showed that a patent bleb and a filtration fistula could be found in the surgical site of a rabbit eye during the whole experimental period. Histological analysis further evidenced that the filtering surgical wound healing was a normal healing process without scar formation. This new approach, making use of a self-assembled peptide hydrogel to normalize filtering surgical wound healing, may have potential for glaucoma filtering surgery.

A composite hydrogels-based photonic crystal multi-sensor

International Nuclear Information System (INIS)

Chen, Cheng; Zhu, Zhigang; Zhu, Xiangrong; Yu, Wei; Liu, Mingju; Ge, Qiaoqiao; Shih, Wei-Heng

2015-01-01

A facile route to prepare stimuli-sensitive poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) gelated crystalline colloidal array photonic crystal material was developed. PVA was physically gelated by utilizing an ethanol-assisted method, the resulting hydrogel/crystal composite film was then functionalized with PAA to form an interpenetrating hydrogel film. This sensor film is able to efficiently diffract the visible light and rapidly respond to various environmental stimuli such as solvent, pH and strain, and the accompanying structural color shift can be repeatedly changed and easily distinguished by naked eye. (paper)

The Metabolic Basis of Pollen Thermo-Tolerance: Perspectives for Breeding

Directory of Open Access Journals (Sweden)

Marine J. Paupière

2014-09-01

Full Text Available Crop production is highly sensitive to elevated temperatures. A rise of a few degrees above the optimum growing temperature can lead to a dramatic yield loss. A predicted increase of 1–3 degrees in the twenty first century urges breeders to develop thermo-tolerant crops which are tolerant to high temperatures. Breeding for thermo-tolerance is a challenge due to the low heritability of this trait. A better understanding of heat stress tolerance and the development of reliable methods to phenotype thermo-tolerance are key factors for a successful breeding approach. Plant reproduction is the most temperature-sensitive process in the plant life cycle. More precisely, pollen quality is strongly affected by heat stress conditions. High temperature leads to a decrease of pollen viability which is directly correlated with a loss of fruit production. The reduction in pollen viability is associated with changes in the level and composition of several (groups of metabolites, which play an important role in pollen development, for example by contributing to pollen nutrition or by providing protection to environmental stresses. This review aims to underline the importance of maintaining metabolite homeostasis during pollen development, in order to produce mature and fertile pollen under high temperature. The review will give an overview of the current state of the art on the role of various pollen metabolites in pollen homeostasis and thermo-tolerance. Their possible use as metabolic markers to assist breeding programs for plant thermo-tolerance will be discussed.

The metabolic basis of pollen thermo-tolerance: perspectives for breeding.

Science.gov (United States)

Paupière, Marine J; van Heusden, Adriaan W; Bovy, Arnaud G

2014-09-30

Crop production is highly sensitive to elevated temperatures. A rise of a few degrees above the optimum growing temperature can lead to a dramatic yield loss. A predicted increase of 1-3 degrees in the twenty first century urges breeders to develop thermo-tolerant crops which are tolerant to high temperatures. Breeding for thermo-tolerance is a challenge due to the low heritability of this trait. A better understanding of heat stress tolerance and the development of reliable methods to phenotype thermo-tolerance are key factors for a successful breeding approach. Plant reproduction is the most temperature-sensitive process in the plant life cycle. More precisely, pollen quality is strongly affected by heat stress conditions. High temperature leads to a decrease of pollen viability which is directly correlated with a loss of fruit production. The reduction in pollen viability is associated with changes in the level and composition of several (groups of) metabolites, which play an important role in pollen development, for example by contributing to pollen nutrition or by providing protection to environmental stresses. This review aims to underline the importance of maintaining metabolite homeostasis during pollen development, in order to produce mature and fertile pollen under high temperature. The review will give an overview of the current state of the art on the role of various pollen metabolites in pollen homeostasis and thermo-tolerance. Their possible use as metabolic markers to assist breeding programs for plant thermo-tolerance will be discussed.

Ultrasensitive Wearable Soft Strain Sensors of Conductive, Self-healing, and Elastic Hydrogels with Synergistic "Soft and Hard" Hybrid Networks.

Science.gov (United States)

Liu, Yan-Jun; Cao, Wen-Tao; Ma, Ming-Guo; Wan, Pengbo

2017-08-02

Robust, stretchable, and strain-sensitive hydrogels have recently attracted immense research interest because of their potential application in wearable strain sensors. The integration of the synergistic characteristics of decent mechanical properties, reliable self-healing capability, and high sensing sensitivity for fabricating conductive, elastic, self-healing, and strain-sensitive hydrogels is still a great challenge. Inspired by the mechanically excellent and self-healing biological soft tissues with hierarchical network structures, herein, functional network hydrogels are fabricated by the interconnection between a "soft" homogeneous polymer network and a "hard" dynamic ferric (Fe 3+ ) cross-linked cellulose nanocrystals (CNCs-Fe 3+ ) network. Under stress, the dynamic CNCs-Fe 3+ coordination bonds act as sacrificial bonds to efficiently dissipate energy, while the homogeneous polymer network leads to a smooth stress-transfer, which enables the hydrogels to achieve unusual mechanical properties, such as excellent mechanical strength, robust toughness, and stretchability, as well as good self-recovery property. The hydrogels demonstrate autonomously self-healing capability in only 5 min without the need of any stimuli or healing agents, ascribing to the reorganization of CNCs and Fe 3+ via ionic coordination. Furthermore, the resulted hydrogels display tunable electromechanical behavior with sensitive, stable, and repeatable variations in resistance upon mechanical deformations. Based on the tunable electromechanical behavior, the hydrogels can act as a wearable strain sensor to monitor finger joint motions, breathing, and even the slight blood pulse. This strategy of building synergistic "soft and hard" structures is successful to integrate the decent mechanical properties, reliable self-healing capability, and high sensing sensitivity together for assembling a high-performance, flexible, and wearable strain sensor.

Smart nanocomposite hydrogels based on azo crosslinked graphene oxide for oral colon-specific drug delivery

Science.gov (United States)

Hou, Lin; Shi, Yuyang; Jiang, Guixiang; Liu, Wei; Han, Huili; Feng, Qianhua; Ren, Junxiao; Yuan, Yujie; Wang, Yongchao; Shi, Jinjin; Zhang, Zhenzhong

2016-08-01

A safe and efficient nanocomposite hydrogel for colon cancer drug delivery was synthesized using pH-sensitive and biocompatible graphene oxide (GO) containing azoaromatic crosslinks as well as poly (vinyl alcohol) (PVA) (GO-N=N-GO/PVA composite hydrogels). Curcumin (CUR), an anti-cancer drug, was encapsulated successfully into the hydrogel through a freezing and thawing process. Fourier transform infrared spectroscopy, scanning electron microscopy and Raman spectroscopy were performed to confirm the formation and morphological properties of the nanocomposite hydrogel. The hydrogels exhibited good swelling properties in a pH-sensitive manner. Drug release studies under conditions mimicking stomach to colon transit have shown that the drug was protected from being released completely into the physiological environment of the stomach and small intestine. In vivo imaging analysis, pharmacokinetics and a distribution of the gastrointestinal tract experiment were systematically studied and evaluated as colon-specific drug delivery systems. All the results demonstrated that GO-N=N-GO/PVA composite hydrogels could protect CUR well while passing through the stomach and small intestine to the proximal colon, and enhance the colon-targeting ability and residence time in the colon site. Therefore, CUR loaded GO-N=N-GO/PVA composite hydrogels might potentially provide a theoretical basis for the treatment of colon cancer with high efficiency and low toxicity.

Synthesis and Properties of IPN Hydrogels Based on Konjac Glucomannan and Poly(acrylic acid)

Institute of Scientific and Technical Information of China (English)

Bing LIU; Zhi Lan LIU; Ren Xi ZHUO

2006-01-01

Novel interpenetrating polymer network (IPN) hydrogels based on konjac glucomannan (KGM) and poly(acrylic acid) (PAA) were prepared by polymerization and cross-linking of acrylic acid (AA) in the pre-fabricated KGM gel. The IPN gel was analyzed by FT-IR. The studies on the equilibrium swelling ratio of IPN hydrogels revealed their sensitive response to environmental pH value. The results of in vitro degradation showed that the IPN hydrogels retain the enzymatic degradation character of KGM.

Hypoxia-induced angiogenesis is increased by the controlled release of deferoxiamine from gelatin hydrogels.

Science.gov (United States)

Saito, Takashi; Tabata, Yasuhiko

2014-08-01

The objective of this study is to design biodegradable hydrogels for the controlled release of deferoxiamine (DFO) and evaluate their biological activity. When the DFO was added to human umbilical vein endothelial cells cultured in 5.0% O2, the level of hypoxia-inducible factor-1α and vascular endothelial growth factor significantly increased compared with that without DFO. The expression of angiogenesis-related genes was accordingly increased by the DFO addition. An aqueous solution of mixed gelatin and DFO was freeze-dried, and dehydrothermally treated at 140°C for 24h to prepare a gelatin hydrogel incorporating DFO. In the release test with phosphate-buffered saline solution (PBS) at 37°C, an initial DFO release of 60% was observed, followed by no release. When placed in PBS containing collagenase, the hydrogel was enzymatically degraded with time, and consequently released DFO in a degradation-dependent manner. After the hydrogel incorporating DFO was injected intramuscularly into a mouse model of hind limb ischemia, the number of new blood vessels formed was significantly higher than that with free DFO and DFO-free hydrogel. It is concluded that the DFO-containing hydrogel shows promising for inducing angiogenesis locally. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Development of a finite element code to solve thermo-hydro-mechanical coupling and simulate induced seismicity.

Science.gov (United States)

María Gómez Castro, Berta; De Simone, Silvia; Rossi, Riccardo; Larese De Tetto, Antonia; Carrera Ramírez, Jesús

2015-04-01

Coupled thermo-hydro-mechanical modeling is essential for CO2 storage because of (1) large amounts of CO2 will be injected, which will cause large pressure buildups and might compromise the mechanical stability of the caprock seal, (2) the most efficient technique to inject CO2 is the cold injection, which induces thermal stress changes in the reservoir and seal. These stress variations can cause mechanical failure in the caprock and can also trigger induced earthquakes. To properly assess these effects, numerical models that take into account the short and long-term thermo-hydro-mechanical coupling are an important tool. For this purpose, there is a growing need of codes that couple these processes efficiently and accurately. This work involves the development of an open-source, finite element code written in C ++ for correctly modeling the effects of thermo-hydro-mechanical coupling in the field of CO2 storage and in others fields related to these processes (geothermal energy systems, fracking, nuclear waste disposal, etc.), and capable to simulate induced seismicity. In order to be able to simulate earthquakes, a new lower dimensional interface element will be implemented in the code to represent preexisting fractures, where pressure continuity will be imposed across the fractures.

Multiplexed Dosing Assays by Digitally Definable Hydrogel Volumes

DEFF Research Database (Denmark)

Faralli, Adele; Melander, Fredrik; Larsen, Esben Kjær Unmack

2016-01-01

Stable and low-cost multiplexed drug sensitivity assays using small volumes of cells or tissue are in demand for personalized medicine, including patientspecific combination chemotherapy. Spatially defined projected light photopolymerization of hydrogels with embedded active compounds is introduc...

In vivo biocompatibility of p(HPMAm-lac)-PEG hydrogels hybridized with hyaluronan

NARCIS (Netherlands)

Sabbieti, Maria Giovanna; Dubbini, Alessandra; Laus, Fulvio; Paggi, Emanuele; Marchegiani, Andrea; Capitani, Melania; Marchetti, Luigi; Dini, Fabrizio; Vermonden, Tina; Di Martino, Piera; Agas, Dimitrios; Censi, Roberta

2017-01-01

The present study reports on the biocompatibility in vivo after intramuscular and subcutaneous administration in Balb/c mice of vinyl sulphone bearing p(HPMAm-lac1-2)-PEG-p(HPMAm-lac1-2)/thiolated hyaluronic acid hydrogels, designed as novel injectable biomaterials for potential application in the

Electrically conductive gold nanoparticle-chitosan thermosensitive hydrogels for cardiac tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Baei, Payam [Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran (Iran, Islamic Republic of); Cardiovascular Engineering Laboratory, Faculty of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); Jalili-Firoozinezhad, Sasan [Department of Biomedicine and Surgery, University Hospital Basel, University of Basel, Hebelstrasse 20, CH-4031 Basel (Switzerland); Department of Bioengineeringand IBB - Institute for Bioengineering and Biosciences, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); Rajabi-Zeleti, Sareh [Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran (Iran, Islamic Republic of); Tafazzoli-Shadpour, Mohammad [Cardiovascular Engineering Laboratory, Faculty of Biomedical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran (Iran, Islamic Republic of); Baharvand, Hossein, E-mail: Baharvand@royaninstitute.org [Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran (Iran, Islamic Republic of); Department of Developmental Biology, University of Science and Culture, ACECR, Tehran (Iran, Islamic Republic of); Aghdami, Nasser, E-mail: Nasser.Aghdami@royaninstitute.org [Department of Stem Cells and Developmental Biology, Cell Science Research Center, Royan Institute for Stem Cell Biology and Technology, ACECR, Tehran (Iran, Islamic Republic of)

2016-06-01

Injectable hydrogels that resemble electromechanical properties of the myocardium are crucial for cardiac tissue engineering prospects. We have developed a facile approach that uses chitosan (CS) to generate a thermosensitive conductive hydrogel with a highly porous network of interconnected pores. Gold nanoparticles (GNPs) were evenly dispersed throughout the CS matrix in order to provide electrical cues. The gelation response and electrical conductivity of the hydrogel were controlled by different concentrations of GNPs. The CS-GNP hydrogels were seeded with mesenchymal stem cells (MSCs) and cultivated for up to 14 days in the absence of electrical stimulations. CS-GNP scaffolds supported viability, metabolism, migration and proliferation of MSCs along with the development of uniform cellular constructs. Immunohistochemistry for early and mature cardiac markers showed enhanced cardiomyogenic differentiation of MSCs within the CS-GNP compared to the CS matrix alone. The results of this study demonstrate that incorporation of nanoscale electro-conductive GNPs into CS hydrogels enhances the properties of myocardial constructs. These constructs could find utilization for regeneration of other electroactive tissues. - Highlights: • Thermosensitive electro-conductive hydrogels were prepared from CS and GNPs. • Gelation time and conductivity were tuned by varying concentration of GNPs. • CS-2GNP with gelation time of 25.7 min and conductivity of 0.13 S·m{sup −1} was selected for in vitro studies. • CS-2GNP supported active metabolism, migration and proliferation of MSCs. • Expression of cardiac markers increased about two-fold in CS-2GNP compared to CS.

Electrically conductive gold nanoparticle-chitosan thermosensitive hydrogels for cardiac tissue engineering

International Nuclear Information System (INIS)

Baei, Payam; Jalili-Firoozinezhad, Sasan; Rajabi-Zeleti, Sareh; Tafazzoli-Shadpour, Mohammad; Baharvand, Hossein; Aghdami, Nasser

2016-01-01

Injectable hydrogels that resemble electromechanical properties of the myocardium are crucial for cardiac tissue engineering prospects. We have developed a facile approach that uses chitosan (CS) to generate a thermosensitive conductive hydrogel with a highly porous network of interconnected pores. Gold nanoparticles (GNPs) were evenly dispersed throughout the CS matrix in order to provide electrical cues. The gelation response and electrical conductivity of the hydrogel were controlled by different concentrations of GNPs. The CS-GNP hydrogels were seeded with mesenchymal stem cells (MSCs) and cultivated for up to 14 days in the absence of electrical stimulations. CS-GNP scaffolds supported viability, metabolism, migration and proliferation of MSCs along with the development of uniform cellular constructs. Immunohistochemistry for early and mature cardiac markers showed enhanced cardiomyogenic differentiation of MSCs within the CS-GNP compared to the CS matrix alone. The results of this study demonstrate that incorporation of nanoscale electro-conductive GNPs into CS hydrogels enhances the properties of myocardial constructs. These constructs could find utilization for regeneration of other electroactive tissues. - Highlights: • Thermosensitive electro-conductive hydrogels were prepared from CS and GNPs. • Gelation time and conductivity were tuned by varying concentration of GNPs. • CS-2GNP with gelation time of 25.7 min and conductivity of 0.13 S·m"−"1 was selected for in vitro studies. • CS-2GNP supported active metabolism, migration and proliferation of MSCs. • Expression of cardiac markers increased about two-fold in CS-2GNP compared to CS.

Pharmacokinetic properties and antitumor efficacy of the 5-fluorouracil loaded PEG-hydrogel

Directory of Open Access Journals (Sweden)

Kim Bokyung

2010-05-01

Full Text Available Abstract Background We have studied the in vitro and in vivo utility of polyethylene glycol (PEG-hydrogels for the development of an anticancer drug 5-fluorouracil (5-FU delivery system. Methods A 5-FU-loaded PEG-hydrogel was implanted subcutaneously to evaluate the drug retention time and the anticancer effect. For the pharmacokinetic study, two groups of male rats were administered either an aqueous solution of 5-FU (control group/or a 5-FU-loaded PEG-hydrogel (treated group at a dose of 100 mg/kg. For the pharmacodynamic study, a human non-small-cell lung adenocarcinoma (NSCLC cell line, A549 was inoculated to male nude mice with a cell density of 3 × 106. Once tumors start growing, the mice were injected with 5-FU/or 5-FU-loaded PEG-hydrogel once a week for 4 weeks. The growth of the tumors was monitored by measuring the tumor volume and calculating the tumor inhibition rate (IR over the duration of the study. Results In the pharmacokinetic study, the 5-FU-loaded PEG-hydrogel gave a mean residence time (MRT of 8.0 h and the elimination half-life of 0.9 h; these values were 14- and 6-fold, respectively, longer than those for the free solution of 5-FU (p Conclusion We suggest that 5-FU-loaded PEG-hydrogels could provide a useful tool for the development of an anticancer drug delivery system.

Intra-articular Administration of Chitosan Thermosensitive In Situ Hydrogels Combined With Diclofenac Sodium-Loaded Alginate Microspheres.

Science.gov (United States)

Qi, Xiaole; Qin, Xiaoxue; Yang, Rong; Qin, Jiayi; Li, Wenyan; Luan, Kun; Wu, Zhenghong; Song, Li

2016-01-01

The aims of this study were to prepare fine intra-articular-administrated chitosan thermosensitive hydrogels combined with alginate microspheres and to investigate the possibility of those hydrogels as a drug delivery system for promoting the anti-inflammation effect. Diclofenac sodium containing alginate microspheres was prepared by a modified emulsification and/or gelation method and then dispersed into injectable thermosensitive hydrogels, consisting of chitosan and β-glycerophosphate. The final combined hydrogels were evaluated in terms of their morphology properties, rheological properties, in vitro drug release, and in vivo biocompatibility and pharmacodynamics behaviors. The optimized formulation exhibited sol-gel transition at 31.72 ± 0.42°C and quickly turned into gel within 5 min, with sustained drug release characteristics followed Ritger-Peppas equation, which could prolong the in vitro drug release to 5 days. In addition, the anti-inflammation efficacy of the combined hydrogels in rabbits with experimental rheumatoid arthritis was higher than that of drug solution and pure chitosan hydrogels. Those results demonstrated that these combined hydrogels could become a potential drug delivery system for improving the therapeutic effect of diclofenac sodium and suggested an important technology platform for intra-articular administration. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Radiation synthesis of functionalising polymer and creation of composition materials on their basis

International Nuclear Information System (INIS)

Mun, G.A.; Nurkeeva, Z.S.; Akhmetkalieva, G.T.; Urkimbaeva, P.I.; Park, L.K.; Lyssukhin, S.N.; Chakrov, P.V.

2005-01-01

Full text: Hydrogels are three-dimensional crosslinked hydrophilic polymers capable of swelling in water and retaining possibly huge volumes of water in the swollen state. The ability of polymer gels to undergo substantial swelling and collapse, as a function of their environment is one of the most remarkable properties of these materials. By this reason such polymer hydrogels belong to so-called 'intelligent', 'smart' or stimuli-responsive materials. The phenomenon of gel volume transitions, which can be induced by temperature, pH, ionic environment and electric fields, has prompted researchers to investigate gels as potential sensors, force actuators, controllable membranes for separations, and modulators for delivery of drugs and other molecules. One of the most perspective applications of stimuli-responsive hydrogels is the designing of controlled drug delivery devices for medicine. In particular, so-called thermo-responsible hydrogels, which undergo a volume phase transition in an aqueous environment induced by a change in temperature, are the most interesting class of stimuli-responsive polymers. It should be noted that all such polymers were obtained usually by homo polymerization of amphiphilic monomers which have hydrophilic and hydrophobic fragments in their structure simultaneously. We used another approach for synthesis of thermo sensitive polymers of linear and cross-linked structure. This approach includes radiation copolymerization of monomers having significant difference in hydrophobic/hydrophilic balance. Some of thermo-sensitive hydrogels and water-soluble polymers were obtained by copolymerization of the following monomeric pairs: vinyl ether of ethyleneglycol (VEEG)-vinyl butyl ether (VBE), VEEG-vinyl isobutyl ether, vinyl ether of diethyleneglycol-VBE, VEEG-hydroxyethylmethacrylate (HEMA), hydroxyethylacrylate (HEA)-HEMA, HEA- butylacrylate, HEA-methylacrylate. The synthesis regularities have been studied. The linear copolymers show lower

Mussel-inspired fabrication of konjac glucomannan/microcrystalline cellulose intelligent hydrogel with pH-responsive sustained release behavior.

Science.gov (United States)

Wang, Lin; Du, Yu; Yuan, Yi; Mu, Ruo-Jun; Gong, Jingni; Ni, Yongsheng; Pang, Jie; Wu, Chunhua

2018-07-01

Intelligent hydrogels are attractive biomaterials for various applications, however, fabricating a hydrogel with both adequate self-healing ability and mechanical properties remains a challenge. Herein, a series of novel intelligent konjac glucomannan (KGM)/microcrystalline cellulose (MCC) hydrogels were prepared vis the mussel-inspired chemistry. MCC was firstly functionalized by the oxidative polymerization of dopamine, and the intelligent hydrogels were obtained by mixing aqueous solutions of KGM and functionalized MCC (PDMCC). By introducing PDMCC, a more compact interconnected porous structure formed for the resulting hydrogels. The self-healing ability and mechanical properties of intelligent hydrogels were dependence on the PDMCC content. Compared with KGM hydrogels, KGM/PDMCC hydrogels exhibited a more distinct pH sensitivity and a lower initial burst release, which was attributed to the compact structure and strong intermolecular hydrogen bond interaction between PDMCC and KGM. These results suggest that the KGM/PDMCC intelligent hydrogels may be promising carriers for controlled drug delivery. Copyright © 2018 Elsevier B.V. All rights reserved.

Improving the performance of electrochemical microsensors based on enzymes entrapped in a redox hydrogel

International Nuclear Information System (INIS)

Mitala, J.J.; Michael, A.C.

2006-01-01

Microsensors based on carbon fiber microelectrodes coated with enzyme-entrapping redox hydrogels facilitate the in vivo detection of substances of interest within the central nervous system, including hydrogen peroxide, glucose, choline and glutamate. The hydrogel, formed by cross-linking a redox polymer, entraps the enzymes and mediates electron transfer between the enzymes and the electrode. It is important that the enzymes are entrapped in their enzymatically active state. Should entrapment cause enzyme denaturation, the sensitivity and the selectivity of the sensor may be compromised. Synthesis of the redox polymer according to published procedures may yield a product that precipitates when added to aqueous enzyme solutions. Casting hydrogels from solutions that contain the precipitate produces microsensors with low sensitivity and selectivity, suggesting that the precipitation disrupts the structure of the enzymes. Herein, we show that a surfactant, sodium dodecyl sulfate (SDS), can prevent the precipitation and improve the sensitivity and selectivity of the sensors

Carbon nanotube-incorporated collagen hydrogels improve cell alignment and the performance of cardiac constructs

Directory of Open Access Journals (Sweden)

Sun HY

2017-04-01

Full Text Available Hongyu Sun,* Jing Zhou,* Zhu Huang,* Linlin Qu,* Ning Lin,* Chengxiao Liang, Ruiwu Dai, Lijun Tang, Fuzhou Tian General Surgery Center, Chengdu Military General Hospital, Chengdu, China *These authors contributed equally to this work Abstract: Carbon nanotubes (CNTs provide an essential 2-D microenvironment for cardiomyocyte growth and function. However, it remains to be elucidated whether CNT nanostructures can promote cell–cell integrity and facilitate the formation of functional tissues in 3-D hydrogels. Here, single-walled CNTs were incorporated into collagen hydrogels to fabricate (CNT/Col hydrogels, which improved mechanical and electrical properties. The incorporation of CNTs (up to 1 wt% exhibited no toxicity to cardiomyocytes and enhanced cell adhesion and elongation. Through the use of immunohistochemical staining, transmission electron microscopy, and intracellular calcium-transient measurement, the incorporation of CNTs was found to improve cell alignment and assembly remarkably, which led to the formation of engineered cardiac tissues with stronger contraction potential. Importantly, cardiac tissues based on CNT/Col hydrogels were noted to have better functionality. Collectively, the incorporation of CNTs into the Col hydrogels improved cell alignment and the performance of cardiac constructs. Our study suggests that CNT/Col hydrogels offer a promising tissue scaffold for cardiac constructs, and might serve as injectable biomaterials to deliver cell or drug molecules for cardiac regeneration following myocardial infarction in the near future. Keywords: carbon nanotubes, collagen hydrogel, cardiac constructs, cell alignment, tissue functionality

Thermogelling chitosan–collagen–bioactive glass nanoparticle hybrids as potential injectable systems for tissue engineering

Energy Technology Data Exchange (ETDEWEB)

Moreira, Cheisy D.F.; Carvalho, Sandhra M.; Mansur, Herman S., E-mail: hmansur@demet.ufmg.br; Pereira, Marivalda M., E-mail: mpereira@demet.ufmg.br

2016-01-01

Recently, stimuli-responsive nanocomposite-derived hydrogels have gained prominence in tissue engineering because they can be applied as injectable scaffolds in bone and cartilage repair. Due to the great potential of these systems, this study aimed to synthesize and characterize novel thermosensitive chitosan-based composites, chemically modified with collagen and reinforced by bioactive glass nanoparticles (BG) on the development of injectable nanohybrids for regenerative medicine applications. Thus, the composite hydrogels were extensively characterized by structural, morphological, rheological, and biological testing. The composites showed thermosensitive response with the gelation temperature at approximately 37 °C, which is compatible with the human body temperature. In addition, scanning electron microscopy (SEM) analysis indicated that the chitosan hydrogels exhibited 3D-porous structures, and the incorporation of collagen in the system caused increase on the average pore size. Fourier transform infrared spectroscopy (FTIR) analysis indicated the main functional groups of each component of the composite system and their chemical interactions forming the scaffold. Moreover, rheological measurements were employed to assess the viscoelastic behavior of the hydrogels as a function of the temperature. The results demonstrated that the addition of collagen and bioactive glass increases the mechanical properties after the gelation process. The addition of 2 wt.% of BG nanoparticles caused an increase of approximately 39% on stiffness compared to pure chitosan and the addition of 30 wt.% collagen caused a further increase on the stiffness by 95%. The cytotoxicity and cell viability of the hydrogels were assessed by MTT and LIVE/DEAD® assays, where the results demonstrated no toxic effect of the composites on the human osteosarcoma cell culture (SAOS) and kidney cells line of human embryo (HEK 293T). Hence, it can be stated that innovative composites were

Single intravitreal bevacizumab injection effects on contrast sensitivity in macular edema from branch retinal vein occlusion

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Rony Carlos Preti

2012-02-01

Full Text Available PURPOSE: To evaluate the effect of a single intravitreal bevacizumab injection on visual acuity, contrast sensitivity and optical coherence tomography-measured central macular thickness in eyes with macular edema from branch retinal vein occlusion. METHODS: Seventeen eyes of 17 patients with macular edema from unilateral branch retinal vein occlusion were treated with a single bevacizumab injection. Patients were submitted to a complete evaluation including best corrected visual acuity, contrast sensitivity and optical coherence tomography measurements before treatment and one and three months after injection. Visual acuity, contrast sensitivity and optical coherence tomography measurements were compared to baseline values. RESULTS: Mean visual acuity measurement improved from 0.77 logMAR at baseline to 0.613 logMAR one month after injection (P=0.0001 but worsened to 0.75 logMAR after three months. Contrast sensitivity test demonstrated significant improvement at spatial frequencies of 3, 6, 12 and 18 cycles/degree one month after injection and at the spatial frequency of 12 cycles/degree three months after treatment. Mean ± standard deviation baseline central macular thickness (552 ± 150 µm reduced significantly one month (322 ± 127 µm, P=0.0001 and three months (439 ± 179 µm, P=0.01 after treatment. CONCLUSIONS: Bevacizumab injection improves visual acuity and contrast sensitivity and reduces central macular thickness one month after treatment. Visual acuity returns to baseline levels at the 3-month follow-up, but some beneficial effect of the treatment is still present at that time, as evidenced by optical coherence tomography-measured central macular thickness and contrast sensitivity measurements.

Extremely stretchable thermosensitive hydrogels by introducing slide-ring polyrotaxane cross-linkers and ionic groups into the polymer network

Science.gov (United States)

Bin Imran, Abu; Esaki, Kenta; Gotoh, Hiroaki; Seki, Takahiro; Ito, Kohzo; Sakai, Yasuhiro; Takeoka, Yukikazu

2014-01-01

Stimuli-sensitive hydrogels changing their volumes and shapes in response to various stimulations have potential applications in multiple fields. However, these hydrogels have not yet been commercialized due to some problems that need to be overcome. One of the most significant problems is that conventional stimuli-sensitive hydrogels are usually brittle. Here we prepare extremely stretchable thermosensitive hydrogels with good toughness by using polyrotaxane derivatives composed of α-cyclodextrin and polyethylene glycol as cross-linkers and introducing ionic groups into the polymer network. The ionic groups help the polyrotaxane cross-linkers to become well extended in the polymer network. The resulting hydrogels are surprisingly stretchable and tough because the cross-linked α-cyclodextrin molecules can move along the polyethylene glycol chains. In addition, the polyrotaxane cross-linkers can be used with a variety of vinyl monomers; the mechanical properties of the wide variety of polymer gels can be improved by using these cross-linkers. PMID:25296246

Smart hydrogel functional materials

CERN Document Server

Chu, Liang-Yin; Ju, Xiao-Jie

2014-01-01

This book systematically introduces smart hydrogel functional materials with the configurations ranging from hydrogels to microgels. It serves as an excellent reference for designing and fabricating artificial smart hydrogel functional materials.

Smart Polymeric Hydrogels for Cartilage Tissue Engineering: A Review on the Chemistry and Biological Functions.

Science.gov (United States)

Eslahi, Niloofar; Abdorahim, Marjan; Simchi, Abdolreza

2016-11-14

Stimuli responsive hydrogels (SRHs) are attractive bioscaffolds for tissue engineering. The structural similarity of SRHs to the extracellular matrix (ECM) of many tissues offers great advantages for a minimally invasive tissue repair. Among various potential applications of SRHs, cartilage regeneration has attracted significant attention. The repair of cartilage damage is challenging in orthopedics owing to its low repair capacity. Recent advances include development of injectable hydrogels to minimize invasive surgery with nanostructured features and rapid stimuli-responsive characteristics. Nanostructured SRHs with more structural similarity to natural ECM up-regulate cell-material interactions for faster tissue repair and more controlled stimuli-response to environmental changes. This review highlights most recent advances in the development of nanostructured or smart hydrogels for cartilage tissue engineering. Different types of stimuli-responsive hydrogels are introduced and their fabrication processes through physicochemical procedures are reported. The applications and characteristics of natural and synthetic polymers used in SRHs are also reviewed with an outline on clinical considerations and challenges.

New Hydrogels Enriched with Antioxidants from Saffron Crocus Can Find Applications in Wound Treatment and/or Beautification.

Science.gov (United States)

Zeka, Keti; Ruparelia, Ketan C; Sansone, Claudia; Macchiarelli, Guido; Continenza, Maria Adelaide; Arroo, Randolph R J

2018-01-01

Saffron extracts have a long history of application as skin protectant, possibly due to their ability to scavenge free radicals. In this work, the performance of a hydrogel enriched with antioxidant compounds isolated from saffron crocus (Crocus sativus L.) petals was tested. These hydrogels could be considered as new drug delivery system. Hydrogels are crosslinked polymer networks that absorb large quantities of water but retain the properties of a solid, thus making ideal dressings for sensitive skin. We tested antioxidant-enriched hydrogels on primary mouse fibroblasts. Hydrogels enriched with kaempferol and crocin extracted from saffron petals showed good biocompatibility with in vitro cultured fibroblasts. These new types of hydrogels may find applications in wound treatment and/or beautification. © 2018 S. Karger AG, Basel.

About the Sterilization of Chitosan Hydrogel Nanoparticles.

Directory of Open Access Journals (Sweden)

Raquel Galante

Full Text Available In the last years, nanostructured biomaterials have raised a great interest as platforms for delivery of drugs, genes, imaging agents and for tissue engineering applications. In particular, hydrogel nanoparticles (HNP associate the distinctive features of hydrogels (high water uptake capacity, biocompatibility with the advantages of being possible to tailor its physicochemical properties at nano-scale to increase solubility, immunocompatibility and cellular uptake. In order to be safe, HNP for biomedical applications, such as injectable or ophthalmic formulations, must be sterile. Literature is very scarce with respect to sterilization effects on nanostructured systems, and even more in what concerns HNP. This work aims to evaluate the effect and effectiveness of different sterilization methods on chitosan (CS hydrogel nanoparticles. In addition to conventional methods (steam autoclave and gamma irradiation, a recent ozone-based method of sterilization was also tested. A model chitosan-tripolyphosphate (TPP hydrogel nanoparticles (CS-HNP, with a broad spectrum of possible applications was produced and sterilized in the absence and in the presence of protective sugars (glucose and mannitol. Properties like size, zeta potential, absorbance, morphology, chemical structure and cytotoxicity were evaluated. It was found that the CS-HNP degrade by autoclaving and that sugars have no protective effect. Concerning gamma irradiation, the formation of agglomerates was observed, compromising the suspension stability. However, the nanoparticles resistance increases considerably in the presence of the sugars. Ozone sterilization did not lead to significant physical adverse effects, however, slight toxicity signs were observed, contrarily to gamma irradiation where no detectable changes on cells were found. Ozonation in the presence of sugars avoided cytotoxicity. Nevertheless, some chemical alterations were observed in the nanoparticles.

About the Sterilization of Chitosan Hydrogel Nanoparticles.

Science.gov (United States)

Galante, Raquel; Rediguieri, Carolina F; Kikuchi, Irene Satiko; Vasquez, Pablo A S; Colaço, Rogério; Serro, Ana Paula; Pinto, Terezinha J A

2016-01-01

In the last years, nanostructured biomaterials have raised a great interest as platforms for delivery of drugs, genes, imaging agents and for tissue engineering applications. In particular, hydrogel nanoparticles (HNP) associate the distinctive features of hydrogels (high water uptake capacity, biocompatibility) with the advantages of being possible to tailor its physicochemical properties at nano-scale to increase solubility, immunocompatibility and cellular uptake. In order to be safe, HNP for biomedical applications, such as injectable or ophthalmic formulations, must be sterile. Literature is very scarce with respect to sterilization effects on nanostructured systems, and even more in what concerns HNP. This work aims to evaluate the effect and effectiveness of different sterilization methods on chitosan (CS) hydrogel nanoparticles. In addition to conventional methods (steam autoclave and gamma irradiation), a recent ozone-based method of sterilization was also tested. A model chitosan-tripolyphosphate (TPP) hydrogel nanoparticles (CS-HNP), with a broad spectrum of possible applications was produced and sterilized in the absence and in the presence of protective sugars (glucose and mannitol). Properties like size, zeta potential, absorbance, morphology, chemical structure and cytotoxicity were evaluated. It was found that the CS-HNP degrade by autoclaving and that sugars have no protective effect. Concerning gamma irradiation, the formation of agglomerates was observed, compromising the suspension stability. However, the nanoparticles resistance increases considerably in the presence of the sugars. Ozone sterilization did not lead to significant physical adverse effects, however, slight toxicity signs were observed, contrarily to gamma irradiation where no detectable changes on cells were found. Ozonation in the presence of sugars avoided cytotoxicity. Nevertheless, some chemical alterations were observed in the nanoparticles.

Water Recycling removal using temperature-sensitive hydronen

Energy Technology Data Exchange (ETDEWEB)

Rana B. Gupta

2002-10-30

The overall objective of this project was to study the proposed Water Recycling/Removal Using Temperature-Sensitive Hydrogels. The main element of this technology is the design of a suitable hydrogel that can perform needed water separation for pulp and paper industry. The specific topics studied are to answer following questions: (a) Can water be removed using hydrogel from large molecules such as lignin? (b) Can the rate of separation be made faster? (c) What are the molecular interactions with hydrogel surface? (d) Can a hydrogel be designed for a high ionic strength and high temperature? Summary of the specific results are given.

Zinc-Triggered Hydrogelation of Self-assembled Small Molecules to Inhibit Bacterial Growth

Science.gov (United States)

Xu, Chao; Cai, Yanbin; Ren, Chunhua; Gao, Jie; Hao, Jihui

2015-01-01

There is a significant need to develop antibacterial materials that could be applied locally and directly to the places surrounded by large amount of bacteria, in order to address the problems of bacterial antibiotic-resistance or irreversible biofilm formation. Hydrogels are thought to be suitable candidates due to their versatile applications in biomedical field. Among them, small molecular hydrogels have been paid lots of attention because they are easy to design and fabricate and often sensitive to external stimuli. Meanwhile, the antibacterial activity of metal ions are attracting more and more attention because resistance to them are not yet found within bacteria. We therefore designed the zinc ion binding peptide of Nap-GFFYGGGHGRGD, who can self-assemble into hydrogels after binds Zn2+ and inhibit the growth of bacteria due to the excellent antibacterial activity of Zn2+. Upon the addition of zinc ions, solutions containing Nap-GFFYGGGHGRGD transformed into supramolecular hydrogels composed of network of long nano-fibers. Bacterial tests revealed an antibacterial effect of the zinc triggered hydrogels on E. coli. The studied small molecular hydrogel shows great potential in locally addressing bacterial infections.

A study on the swelling behavior of poly(acrylic acid) hydrogels obtained by electron beam crosslinking

Science.gov (United States)

Sheikh, N.; Jalili, L.; Anvari, F.

2010-06-01

Poly(acrylic acid) (PAA) hydrogels were prepared by using electron beam (EB) crosslinking of PAA homopolymer from its aqueous solutions. The swelling behavior of the hydrogels was studied as a function of the concentration of PAA solution, radiation dose, pH of the swelling medium and swelling time. Also the environmental pH effect on the water diffusion mode into hydrogels was investigated. These hydrogels clearly showed pH-sensitive swelling behavior with Fickian type of diffusion in the stomach-like pH medium (pH 1.3) and non-Fickian type in the intestine-like pH medium (pH 6.8).

A study on the swelling behavior of poly(acrylic acid) hydrogels obtained by electron beam crosslinking

International Nuclear Information System (INIS)

Sheikh, N.; Jalili, L.; Anvari, F.

2010-01-01

Poly(acrylic acid) (PAA) hydrogels were prepared by using electron beam (EB) crosslinking of PAA homopolymer from its aqueous solutions. The swelling behavior of the hydrogels was studied as a function of the concentration of PAA solution, radiation dose, pH of the swelling medium and swelling time. Also the environmental pH effect on the water diffusion mode into hydrogels was investigated. These hydrogels clearly showed pH-sensitive swelling behavior with Fickian type of diffusion in the stomach-like pH medium (pH 1.3) and non-Fickian type in the intestine-like pH medium (pH 6.8).

Gradient nano-engineered in situ forming composite hydrogel for osteochondral regeneration.

Science.gov (United States)

Radhakrishnan, Janani; Manigandan, Amrutha; Chinnaswamy, Prabu; Subramanian, Anuradha; Sethuraman, Swaminathan

2018-04-01

Fabrication of anisotropic osteochondral-mimetic scaffold with mineralized subchondral zone and gradient interface remains challenging. We have developed an injectable semi-interpenetrating network hydrogel construct with chondroitin sulfate nanoparticles (ChS-NPs) and nanohydroxyapatite (nHA) (∼30-90 nm) in chondral and subchondral hydrogel zones respectively. Mineralized subchondral hydrogel exhibited significantly higher osteoblast proliferation and alkaline phosphatase activity (p gradient interface of nHA and ChS-NPs. Microcomputed tomography (μCT) demonstrated nHA gradation while rheology showed predominant elastic modulus (∼930 Pa) at the interface. Co-culture of osteoblasts and chondrocytes in gradient hydrogels showed layer-specific retention of cells and cell-cell interaction at the interface. In vivo osteochondral regeneration by biphasic (nHA or ChS) and gradient (nHA + ChS) hydrogels was compared with control using rabbit osteochondral defect after 3 and 8 weeks. Complete closure of defect was observed in gradient (8 weeks) while defect remained in other groups. Histology demonstrated collagen and glycosaminoglycan deposition in neo-matrix and presence of hyaline cartilage-characteristic matrix, chondrocytes and osteoblasts. μCT showed mineralized neo-tissue formation, which was confined within the defect with higher bone mineral density in gradient (chondral: 0.42 ± 0.07 g/cc, osteal: 0.64 ± 0.08 g/cc) group. Further, biomechanical push-out studies showed significantly higher load for gradient group (378 ± 56 N) compared to others. Thus, the developed nano-engineered gradient hydrogel enhanced hyaline cartilage regeneration with subchondral bone formation and lateral host-tissue integration. Copyright © 2018 Elsevier Ltd. All rights reserved.

Stimulus responsive hydrogel-coated etched fiber Bragg grating for carcinogenic chromium (VI) sensing

Science.gov (United States)

Kishore, Pabbisetti Vayu Nandana; Madhuvarasu, Sai Shankar; Moru, Satyanarayana

2018-01-01

This paper proposes a chemo-mechanical-optical sensing approach for the detection of carcinogenic chromium (VI) metal ion using an etched fiber Bragg grating (FBG) coated with stimulus responsive hydrogel. Hydrogel synthesized from the blends of (3-acrylamidopropyl)-trimethylammonium chloride, which is highly responsive to chromium ions suffers a volume change when placed in Cr solution. When the proposed sensor system is exposed to various concentrations of Cr (VI) ion solution, FBG peak shifts due to the mechanical strain induced by the swelling of the hydrogel. The peak shift is correlated with the concentration of the Cr (VI) metal ion. Due to the reduction in the cladding diameter of FBG, wastage of swelling force due to hydrogel on FBG is lowered and utilized for more wavelength peak shift of FBG resulting in the increase in the sensitivity. The resolution of the sensor system is found to be 0.072 ppb. Trace amounts of chromium (VI) ion as low as 10 ppb can be sensed by this method. The sensor has shown good sensitivity, selectivity, and repeatability. The salient features of the sensors are its compact size, light weight, and adoptability for remote monitoring.

A reduction of diffusion in PVA Fricke hydrogels

International Nuclear Information System (INIS)

Smith, S T; Masters, K S; Hosokawa, K; Blinco, J; Crowe, S B; Kairn, T; Trapp, J V

2015-01-01

A modification to the PVA-FX hydrogel whereby the chelating agent, xylenol orange, was partially bonded to the gelling agent, poly-vinyl alcohol, resulted in an 8% reduction in the post irradiation Fe 3+ diffusion, adding approximately 1 hour to the useful timespan between irradiation and readout. This xylenol orange functionalised poly-vinyl alcohol hydrogel had an OD dose sensitivity of 0.014 Gy −1 and a diffusion rate of 0.133 mm 2 h −1 . As this partial bond yields only incremental improvement, it is proposed that more efficient methods of bonding xylenol orange to poly-vinyl alcohol be investigated to further reduce the diffusion in Fricke gels

Hydrogels for efficient light delivery in optogenetic applications

Science.gov (United States)

Johannsmeier, S.; Torres, M. L.; Ripken, T.; Heinemann, D.; Heisterkamp, A.

2018-02-01

Light-based therapies have been established for various indications, such as skin conditions, cancer or neonatal jaundice. Advances in the field of optogenetics open up new horizons for light-tissue interactions with an organism-wide impact. Excitable tissues, such as nerve and muscle tissues, can be controlled by light after the introduction of light-sensitive ion channels. Since these organs are generally not easily accessible to illumination in vivo, there is an increasing need for effective biocompatible waveguides for light delivery. These devices not only have to guide and distribute the light as desired with minimal losses, they should also mimic the mechanical properties of the surrounding tissue to ensure compatibility. In this project, we are tuning the properties of hydrogels from poly(ethylene glycol) derivatives to achieve compatibility with muscle tissue as well as optimal light guiding and distribution for optogenetic applications at the heart. The excitation light is coupled into the hydrogel with a biocompatible fiber. Properties of the hydrogel are mainly tuned by monomer length and concentration. Total reflection can be achieved by embedding a fiber-like hydrogel with a high refractive index into a second, low refractive index gel. Different geometries and scattering microparticles are used for light distribution in a flat gel patch. Targeted cell attachment can be achieved by introducing a protein layer to the otherwise bioinert gel. After optimization, the hydrogel may be used to deliver light for the excitation of genetically altered cardiomyocytes for controlled contraction.

Preparation and physico-chemical properties of hydrogels from carboxymethyl cassava starch crosslinked with citric acid

Science.gov (United States)

Boonkham, Sasikan; Sangseethong, Kunruedee; Chatakanon, Pathama; Niamnuy, Chalida; Nakasaki, Kiyohiko; Sriroth, Klanarong

2014-06-01

Recently, environmentally friendly hydrogels prepared from renewable bio-based resources have drawn significant attention from both industrial and academic sectors. In this study, chemically crosslinked hydrogels have been developed from cassava starch which is a bio-based polymer using a non-toxic citric acid as a crosslinking agent. Cassava starch was first modified by carboxymethylation to improve its water absorbency property. The carboxymethyl cassava starch (CMCS) obtained was then crosslinked with citric acid at different concentrations and reaction times. The gel fraction of hydrogels increased progressively with increasing citric acid concentration. Free swelling capacity of hydrogels in de-ionized water, saline solution and buffers at various pHs as well as absorption under load were investigated. The results revealed that swelling behavior and mechanical characteristic of hydrogels depended on the citric acid concentration used in reaction. Increasing citric acid concentration resulted in hydrogels with stronger network but lower swelling and absorption capacity. The cassava starch hydrogels developed were sensitive to ionic strength and pH of surrounding medium, showing much reduced swelling capacity in saline salt solution and acidic buffers.

Retention and Functional Effect of Adipose-Derived Stromal Cells Administered in Alginate Hydrogel in a Rat Model of Acute Myocardial Infarction

Directory of Open Access Journals (Sweden)

Bjarke Follin

2018-01-01

Full Text Available Background. Cell therapy for heart disease has been proven safe and efficacious, despite poor cell retention in the injected area. Improving cell retention is hypothesized to increase the treatment effect. In the present study, human adipose-derived stromal cells (ASCs were delivered in an in situ forming alginate hydrogel following acute myocardial infarction (AMI in rats. Methods. ASCs were transduced with luciferase and tested for ASC phenotype. AMI was inducted in nude rats, with subsequent injection of saline (controls, 1 × 106 ASCs in saline or 1 × 106 ASCs in 1% (w/v alginate hydrogel. ASCs were tracked by bioluminescence and functional measurements were assessed by magnetic resonance imaging (MRI and 82rubidium positron emission tomography (PET. Results. ASCs in both saline and alginate hydrogel significantly increased the ejection fraction (7.2% and 7.8% at 14 days and 7.2% and 8.0% at 28 days, resp.. After 28 days, there was a tendency for decreased infarct area and increased perfusion, compared to controls. No significant differences were observed between ASCs in saline or alginate hydrogel, in terms of retention and functional salvage. Conclusion. ASCs improved the myocardial function after AMI, but administration in the alginate hydrogel did not further improve retention of the cells or myocardial function.

Biomolecule-Responsive Hydrogels in Medicine.

Science.gov (United States)

Sharifzadeh, Ghorbanali; Hosseinkhani, Hossein

2017-12-01

Recent advances and applications of biomolecule-responsive hydrogels, namely, glucose-responsive hydrogels, protein-responsive hydrogels, and nucleic-acid-responsive hydrogels are highlighted. However, achieving the ultimate purpose of using biomolecule-responsive hydrogels in preclinical and clinical areas is still at the very early stage and calls for more novel designing concepts and advance ideas. On the way toward the real/clinical application of biomolecule-responsive hydrogels, plenty of factors should be extensively studied and examined under both in vitro and in vivo conditions. For example, biocompatibility, biointegration, and toxicity of biomolecule-responsive hydrogels should be carefully evaluated. From the living body's point of view, biocompatibility is seriously depended on the interactions at the tissue/polymer interface. These interactions are influenced by physical nature, chemical structure, surface properties, and degradation of the materials. In addition, the developments of advanced hydrogels with tunable biological and mechanical properties which cause no/low side effects are of great importance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In vitro release of metformin hydrochloride from sodium alginate/polyvinyl alcohol hydrogels.

Science.gov (United States)

Martínez-Gómez, Fabián; Guerrero, Juan; Matsuhiro, Betty; Pavez, Jorge

2017-01-02

Hydrogels, based on polysaccharides have found a number of applications as drug delivery carriers. In this work, hydrogels of full characterized sodium alginate (Mn 87,400g/mol) and commercial poly(vinyl alcohol) (PVA) sensitive to pH and temperature stimuli were obtained using a simple, controlled, green, low cost method based on freeze-thaw cycles. Stable hydrogels of sodium alginate/PVA with 0.5:1.5 and 1.0:1.0w/v concentrations showed very good swelling ratio values in distilled water (14 and 20g/g, respectively). Encapsulation and release of metformin hydrochloride in hydrogels of 1.0:1.0w/v sodium alginate/PVA was followed by UV spectroscopy. The hydrogel released a very low amount of metformin hydrochloride at pH 1.2; the highest release value (55%) was obtained after 6h at pH 8.0. Also, the release of metformin hydrochloride was studied by 1 H NMR spectroscopy, the temporal evolution of methyl group signals of metformin showed 30% of drug release after 3h. Copyright © 2016 Elsevier Ltd. All rights reserved.

Microsphere erosion in outer hydrogel membranes creating macroscopic porosity to counter biofouling-induced sensor degradation.

Science.gov (United States)

Vaddiraju, S; Wang, Y; Qiang, L; Burgess, D J; Papadimitrakopoulos, F

2012-10-16

Biofouling and tissue inflammation present major challenges toward the realization of long-term implantable glucose sensors. Following sensor implantation, proteins and cells adsorb on sensor surfaces to not only inhibit glucose flux but also signal a cascade of inflammatory events that eventually lead to permeability-reducing fibrotic encapsulation. The use of drug-eluting hydrogels as outer sensor coatings has shown considerable promise to mitigate these problems via the localized delivery of tissue response modifiers to suppress inflammation and fibrosis, along with reducing protein and cell absorption. Biodegradable poly (lactic-co-glycolic) acid (PLGA) microspheres, encapsulated within a poly (vinyl alcohol) (PVA) hydrogel matrix, present a model coating where the localized delivery of the potent anti-inflammatory drug dexamethasone has been shown to suppress inflammation over a period of 1-3 months. Here, it is shown that the degradation of the PLGA microspheres provides an auxiliary venue to offset the negative effects of protein adsorption. This was realized by: (1) the creation of fresh porosity within the PVA hydrogel following microsphere degradation (which is sustained until the complete microsphere degradation) and (2) rigidification of the PVA hydrogel to prevent its complete collapse onto the newly created void space. Incubation of the coated sensors in phosphate buffered saline (PBS) led to a monotonic increase in glucose permeability (50%), with a corresponding enhancement in sensor sensitivity over a 1 month period. Incubation in serum resulted in biofouling and consequent clogging of the hydrogel microporosity. This, however, was partially offset by the generated macroscopic porosity following microsphere degradation. As a result of this, a 2-fold recovery in sensor sensitivity for devices with microsphere/hydrogel composite coatings was observed as opposed to similar devices with blank hydrogel coatings. These findings suggest that the use of

Dual stimuli-sensitive dendrimers: Photothermogenic gold nanoparticle-loaded thermo-responsive elastin-mimetic dendrimers.

Science.gov (United States)

Fukushima, Daichi; Sk, Ugir Hossain; Sakamoto, Yasuhiro; Nakase, Ikuhiko; Kojima, Chie

2015-08-01

Dendrimers are synthetic macromolecules with unique structures that can work as nanoplatforms for both photothermogenic gold nanoparticles (AuNPs) and thermosensitive elastin-like peptides (ELPs) with valine-proline-glycine-valine-glycine (VPGVG) repeats. In this study, photothermogenic AuNPs were loaded into thermo-responsive elastin-mimetic dendrimers (dendrimers conjugating ELPs at their periphery) to produce dual stimuli-sensitive nanoparticles. Polyamidoamine G4 dendrimers were modified with acetylated VPGVG and (VPGVG)2, and the resulting materials were named ELP1-den and ELP2-den, respectively. The AuNPs were prepared by the reduction of Au ions using a dendrimer-nanotemplated method. The AuNP-loaded elastin-mimetic dendrimers exhibited photothermal properties. ELP1-den and ELP2-den showed similar temperature-dependent changes in their conformations. Phase transitions were observed at around 55°C and 35°C for the AuNP-loaded ELP1-den and AuNP-loaded ELP2-den, respectively, but not for the corresponding PEGylated dendrimer. In contrast to the AuNP-loaded PEGylated dendrimer, AuNP-loaded ELP2-den readily associated with cells and induced efficient photocytotoxicity at 37°C. The cell association and the photocytotoxicity properties of AuNP-loaded ELP2-den could be controlled by temperature. These results therefore suggest that dual stimuli-sensitive dendrimer nanoparticles of this type could be used for photothermal therapy. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of platelet lysate supplementation of a dextran-based hydrogel on cartilage formation.

Science.gov (United States)

Moreira Teixeira, Liliana S; Leijten, Jeroen C H; Wennink, Jos W H; Chatterjea, Anindita G; Feijen, Jan; van Blitterswijk, Clemens A; Dijkstra, Pieter J; Karperien, Marcel

2012-05-01

In situ gelating dextran-tyramine (Dex-TA) injectable hydrogels have previously shown promising features for cartilage repair. Yet, despite suitable mechanical properties, this system lacks intrinsic biological signals. In contrast, platelet lysate-derived hydrogels are rich in growth factors and anti-inflammatory cytokines, but mechanically unstable. We hypothesized that the advantages of these systems may be combined in one hydrogel, which can be easily translated into clinical settings. Platelet lysate was successfully incorporated into Dex-TA polymer solution prior to gelation. After enzymatic crosslinking, rheological and morphological evaluations were performed. Subsequently, the effect of platelet lysate on cell migration, adhesion, proliferation and multi-lineage differentiation was determined. Finally, we evaluated the integration potential of this gel onto osteoarthritis-affected cartilage. The mechanical properties and covalent attachment of Dex-TA to cartilage tissue during in situ gel formation were successfully combined with the advantages of platelet lysate, revealing the potential of this enhanced hydrogel as a cell-free approach. The addition of platelet lysate did not affect the mechanical properties and porosity of Dex-TA hydrogels. Furthermore, platelet lysate derived anabolic growth factors promoted proliferation and triggered chondrogenic differentiation of mesenchymal stromal cells. Copyright © 2012 Elsevier Ltd. All rights reserved.

Biomedical hydrogels biochemistry, manufacture and medical applications

CERN Document Server

Rimmer, Steve

2011-01-01

Hydrogels are very important for biomedical applications because they can be chemically manipulated to alter and control the hydrogel's interaction with cells and tissues. Their flexibility and high water content is similar to that of natural tissue, making them extremely suitable for biomaterials applications. Biomedical hydrogels explores the diverse range and use of hydrogels, focusing on processing methods and novel applications in the field of implants and prostheses. Part one of this book concentrates on the processing of hydrogels, covering hydrogel swelling behaviour, superabsorbent cellulose-based hydrogels and regulation of novel hydrogel products, as well as chapters focusing on the structure and properties of hydrogels and different fabrication technologies. Part two covers existing and novel applications of hydrogels, including chapters on spinal disc and cartilage replacement implants, hydrogels for ophthalmic prostheses and hydrogels for wound healing applications. The role of hydrogels in imag...

In situ synthesis of magnetic CaraPVA IPN nanocomposite hydrogels and controlled drug release

International Nuclear Information System (INIS)

Mahdavinia, Gholam Reza; Etemadi, Hossein

2014-01-01

In this work, the magnetic nanocomposite hydrogels that focused on targeted drug delivery were synthesized by incorporation of polyvinyl alcohol (PVA), kappa-carrageenan (Cara), and magnetite Fe 3 O 4 nanoparticles. The magnetic nanoparticles were obtained in situ in the presence of a mixture of polyvinyl alcohol/kappa-carrageenan (CaraPVA). The produced magnetite-polymers were cross-linked with freezing–thawing technique and subsequent with K + solution. The synthesized hydrogels were thoroughly characterized by transmittance electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) techniques. The dynamic swelling kinetic models of hydrogels were analyzed according to the first- and second-order kinetic models and were found that the experimental kinetics data followed the second-order model well. Drug loading and release efficiency were evaluated by diclofenac sodium (DS) as the model drug. The in vitro drug release studies from hydrogels exhibited significant behaviors on the subject of physiological simulated pHs and external magnetic fields. Investigation on the antibacterial activity revealed the ability of drug-loaded hydrogels to inactivate the Gram-positive Staphylococcus aureus (S. aureus) bacteria. The mucoadhesive properties of the hydrogels were studied and the hydrogels containing kappa-carrageenan showed good mucoadhesiveness in both simulated gastric and intestinal conditions. - Highlights: • In situ synthesis of magnetic kappa-carrageenan/PVA nanocomposite hydrogel. • Low salt sensitivity of magnetic nanocomposite hydrogels was observed. • The release of diclofenac sodium from hydrogels was pH-dependent. • The release of diclofenac sodium from magnetic hydrogels was affected by external magnetic field. • The hydrogels containing carrageenan component showed high mucoadhesiveness

In situ synthesis of magnetic CaraPVA IPN nanocomposite hydrogels and controlled drug release

Energy Technology Data Exchange (ETDEWEB)

Mahdavinia, Gholam Reza, E-mail: grmnia@maragheh.ac.ir; Etemadi, Hossein

2014-12-01

In this work, the magnetic nanocomposite hydrogels that focused on targeted drug delivery were synthesized by incorporation of polyvinyl alcohol (PVA), kappa-carrageenan (Cara), and magnetite Fe{sub 3}O{sub 4} nanoparticles. The magnetic nanoparticles were obtained in situ in the presence of a mixture of polyvinyl alcohol/kappa-carrageenan (CaraPVA). The produced magnetite-polymers were cross-linked with freezing–thawing technique and subsequent with K{sup +} solution. The synthesized hydrogels were thoroughly characterized by transmittance electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) techniques. The dynamic swelling kinetic models of hydrogels were analyzed according to the first- and second-order kinetic models and were found that the experimental kinetics data followed the second-order model well. Drug loading and release efficiency were evaluated by diclofenac sodium (DS) as the model drug. The in vitro drug release studies from hydrogels exhibited significant behaviors on the subject of physiological simulated pHs and external magnetic fields. Investigation on the antibacterial activity revealed the ability of drug-loaded hydrogels to inactivate the Gram-positive Staphylococcus aureus (S. aureus) bacteria. The mucoadhesive properties of the hydrogels were studied and the hydrogels containing kappa-carrageenan showed good mucoadhesiveness in both simulated gastric and intestinal conditions. - Highlights: • In situ synthesis of magnetic kappa-carrageenan/PVA nanocomposite hydrogel. • Low salt sensitivity of magnetic nanocomposite hydrogels was observed. • The release of diclofenac sodium from hydrogels was pH-dependent. • The release of diclofenac sodium from magnetic hydrogels was affected by external magnetic field. • The hydrogels containing carrageenan component showed high

Synthesis and characterization of zinc chloride containing poly(acrylic acid) hydrogel by gamma irradiation

International Nuclear Information System (INIS)

Park, Jong-Seok; Kuang, Jia; Gwon, Hui-Jeong; Lim, Youn-Mook; Jeong, Sung-In; Shin, Young-Min; Seob Khil, Myung; Nho, Young-Chang

2013-01-01

In this study, the characterization of zinc chloride incorporated into a poly(acrylic acid) (PAAc) hydrogel prepared by gamma-ray irradiation was investigated. Zinc chloride powder with different concentrations was dissolved in the PAAc solution, and it was crosslinked with gamma-ray irradiation. The effects of various parameters such as zinc ion concentration and irradiation doses on characteristics of the hydrogel formed were investigated in detail for obtaining an antibacterial wound dressing. In addition, the gel content, pH-sensitive (pH 4 or 7) swelling ratio, and UV–vis absorption spectra of the zinc particles in the hydrogels were characterized. Moreover, antibacterial properties of these new materials against Staphylococcus aureus and Escherichia coli strains were observed on solid growth media. The antibacterial tests indicated that the zinc chloride containing PAAc hydrogels have good antibacterial activity. - Highlights: • The characterization of zinc chloride containing PAA hydrogel was investigated. • The gel content increased with an increase in absorbed dose up to 75 kGy. • Finally, the zinc chloride based hydrogels have an antibacterial activity

Ionic Conductivity of Polyelectrolyte Hydrogels.

Science.gov (United States)

Lee, Chen-Jung; Wu, Haiyan; Hu, Yang; Young, Megan; Wang, Huifeng; Lynch, Dylan; Xu, Fujian; Cong, Hongbo; Cheng, Gang

2018-02-14

Polyelectrolytes have many important functions in both living organisms and man-made applications. One key property of polyelectrolytes is the ionic conductivity due to their porous networks that allow the transport of water and small molecular solutes. Among polyelectrolytes, zwitterionic polymers have attracted huge attention for applications that involve ion transport in a polyelectrolyte matrix; however, it is still unclear how the functional groups of zwitterionic polymer side chains affect their ion transport and swelling properties. In this study, zwitterionic poly(carboxybetaine acrylamide), poly(2-methacryloyloxyethyl phosphorylcholine), and poly(sulfobetaine methacrylate) hydrogels were synthesized and their ionic conductivity was studied and compared to cationic, anionic, and nonionic hydrogels. The change of the ionic conductivity of zwitterionic and nonionic hydrogels in different saline solutions was investigated in detail. Zwitterionic hydrogels showed much higher ionic conductivity than that of the widely used nonionic poly(ethylene glycol) methyl ether methacrylate hydrogel in all tested solutions. For both cationic and anionic hydrogels, the presence of mobile counterions led to high ionic conductivity in low salt solutions; however, the ionic conductivity of zwitterionic hydrogels surpassed that of cationic and ionic hydrogels in high salt solutions. Cationic and anionic hydrogels showed much higher water content than that of zwitterionic hydrogels in deionized water; however, the cationic hydrogels shrank significantly with increasing saline concentration. This work provides insight into the effects of polyelectrolyte side chains on ion transport. This can guide us in choosing better polyelectrolytes for a broad spectrum of applications, including bioelectronics, neural implants, battery, and so on.

Biomimetic hydrogel materials

Science.gov (United States)

Bertozzi, Carolyn; Mukkamala, Ravindranath; Chen, Qing; Hu, Hopin; Baude, Dominique

2000-01-01

Novel biomimetic hydrogel materials and methods for their preparation. Hydrogels containing acrylamide-functionalized carbohydrate, sulfoxide, sulfide or sulfone copolymerized with a hydrophilic or hydrophobic copolymerizing material selected from the group consisting of an acrylamide, methacrylamide, acrylate, methacrylate, vinyl and a derivative thereof present in concentration from about 1 to about 99 wt %. and methods for their preparation. The method of use of the new hydrogels for fabrication of soft contact lenses and biomedical implants.

Cytocompatible cellulose hydrogels containing trace lignin

International Nuclear Information System (INIS)

Nakasone, Kazuki; Kobayashi, Takaomi

2016-01-01

Sugarcane bagasse was used as a cellulose resource to prepare transparent and flexible cellulose hydrogel films. On the purification process from bagasse to cellulose, the effect of lignin residues in the cellulose was examined for the properties and cytocompatibility of the resultant hydrogel films. The cellulose was dissolved in lithium chloride/N,N-dimethylacetamide solution and converted to hydrogel films by phase inversion. In the purification process, sodium hydroxide (NaOH) treatment time was changed from 1 to 12 h. This resulted in cellulose hydrogel films having small amounts of lignin from 1.62 to 0.68%. The remaining lignin greatly affected hydrogel properties. Water content of the hydrogel films was increased from 1153 to 1525% with a decrease of lignin content. Moreover, lower lignin content caused weakening of tensile strength from 0.80 to 0.43 N/mm"2 and elongation from 45.2 to 26.5%. Also, similar tendency was observed in viscoelastic behavior of the cellulose hydrogel films. Evidence was shown that the lignin residue was effective for the high strength of the hydrogel films. In addition, scanning probe microscopy in the morphological observation was suggested that the trace lignin in the cellulose hydrogel affected the cellulose fiber aggregation in the hydrogel network. The trace of lignin in the hydrogels also influenced fibroblast cell culture on the hydrogel films. The hydrogel film containing 1.68% lignin showed better fibroblast compatibility as compared to cell culture polystyrene dish used as reference. - Highlights: • Cellulose hydrogel films with trace lignin were obtained from sugarcane bagasse. • Lignin content was found to be in the range of 1.62 − 0.68% by UV–Vis spectroscopy. • Higher lignin content strengthened mechanical properties of the hydrogel films. • Trace lignin affected the hydrogel morphology such as roughness and porosity. • High cell proliferation was observed in the hydrogel containing 1.68% lignin.

Cytocompatible cellulose hydrogels containing trace lignin

Energy Technology Data Exchange (ETDEWEB)

Nakasone, Kazuki; Kobayashi, Takaomi, E-mail: takaomi@nagaoakut.ac.jp

2016-07-01

Sugarcane bagasse was used as a cellulose resource to prepare transparent and flexible cellulose hydrogel films. On the purification process from bagasse to cellulose, the effect of lignin residues in the cellulose was examined for the properties and cytocompatibility of the resultant hydrogel films. The cellulose was dissolved in lithium chloride/N,N-dimethylacetamide solution and converted to hydrogel films by phase inversion. In the purification process, sodium hydroxide (NaOH) treatment time was changed from 1 to 12 h. This resulted in cellulose hydrogel films having small amounts of lignin from 1.62 to 0.68%. The remaining lignin greatly affected hydrogel properties. Water content of the hydrogel films was increased from 1153 to 1525% with a decrease of lignin content. Moreover, lower lignin content caused weakening of tensile strength from 0.80 to 0.43 N/mm{sup 2} and elongation from 45.2 to 26.5%. Also, similar tendency was observed in viscoelastic behavior of the cellulose hydrogel films. Evidence was shown that the lignin residue was effective for the high strength of the hydrogel films. In addition, scanning probe microscopy in the morphological observation was suggested that the trace lignin in the cellulose hydrogel affected the cellulose fiber aggregation in the hydrogel network. The trace of lignin in the hydrogels also influenced fibroblast cell culture on the hydrogel films. The hydrogel film containing 1.68% lignin showed better fibroblast compatibility as compared to cell culture polystyrene dish used as reference. - Highlights: • Cellulose hydrogel films with trace lignin were obtained from sugarcane bagasse. • Lignin content was found to be in the range of 1.62 − 0.68% by UV–Vis spectroscopy. • Higher lignin content strengthened mechanical properties of the hydrogel films. • Trace lignin affected the hydrogel morphology such as roughness and porosity. • High cell proliferation was observed in the hydrogel containing 1.68% lignin.

Transparent crosslinked ultrashort peptide hydrogel dressing with high shape-fidelity accelerates healing of full-thickness excision wounds

KAUST Repository

Seow, Wei Yang

2016-09-07

Wound healing is a major burden of healthcare systems worldwide and hydrogel dressings offer a moist environment conducive to healing. We describe cysteine-containing ultrashort peptides that self-assemble spontaneously into hydrogels. After disulfide crosslinking, the optically-transparent hydrogels became significantly stiffer and exhibited high shape fidelity. The peptide sequence (LIVAGKC or LK6C) was then chosen for evaluation on mice with full-thickness excision wounds. Crosslinked LK6C hydrogels are handled easily with forceps during surgical procedures and offer an improvement over our earlier study of a non-crosslinked peptide hydrogel for burn wounds. LK6C showed low allergenic potential and failed to provoke any sensitivity when administered to guinea pigs in the Magnusson-Kligman maximization test. When applied topically as a dressing, the medium-infused LK6C hydrogel accelerated re-epithelialization compared to controls. The peptide hydrogel is thus safe for topical application and promotes a superior rate and quality of wound healing.

Ruthenium(II)- bipyridyl with extended π-system: Improved thermo ...

Indian Academy of Sciences (India)

aInorganic and Physical Chemistry Division, Indian Institute of Chemical Technology, Uppal Road, Tarnaka, ... A new extended thermo-stable high molar extinction coefficient bipyridyl ruthenium(II) complex ... cyanines and metal free organic sensitizers have been ..... Iodide-based ionic liquids are more viscous than.

The synthesis of hydrogels with controlled distribution of polymer brushes in hydrogel network

Energy Technology Data Exchange (ETDEWEB)

Sun, YuWei; Zhou, Chao; Zhang, AoKai; Xu, LiQun; Yao, Fang [School of Chemistry and Chemical Engineering, Southeast University, Jiangning District, Nanjing, Jiangsu Province, 211189 (China); Cen, Lian, E-mail: cenlian@hotmail.com [National Tissue Engineering Center of China, No.68, East Jiang Chuan Road, Shanghai, 200241 (China); School of Chemical Engineering, East China University of Science and Technology, No.130, Mei Long Road, Shanghai, 200237 (China); Fu, Guo-Dong, E-mail: fu7352@seu.edu.cn [School of Chemistry and Chemical Engineering, Southeast University, Jiangning District, Nanjing, Jiangsu Province, 211189 (China)

2014-11-30

Highlights: • Many biological tissues are 3-dimensionally asymmetric in structure and properties, it would be desirable if hydrogels could bear such structural similarity with specialized surface and bulk properties. Moreover, gradual but continuous variation in spatial structural and property is also a common phenomenon in biological tissues, such as interfaces between bone and tendon, or between bone and cartilage. Hence, the development of a method to introduce well-defined functional polymer brushes on PEG hydrogels, especially with precisely controlled spatial structure in 3-dimensions, would impart the hydrogels with special functionalities and wider applications. Poly(ethylene glycol) (PEG) hydrogels with 3-dimensionally controlled well-defined poly(N-isopropylacrylamide) (poly(NIPAAm)) brushes were prepared by combined copper(I)-catalyzed azide-alkyne cycloaddition (“Click Chemistry”) and atom transfer radical polymerization (ATRP). The resulting hydrogels were presented as representatives with their detailed synthesis routes and characterization. H{sub PEG}-S-poly(NIPAAm) is a hydrogel with poly(NIPAAm) brushes mainly grafted on surface, whereas H{sub PEG}-G-poly(NIPAAm) has a gradiently decreased poly(NIPAAm) brushes in their chain length from surface to inside. On the other hand, poly(NIPAAm) brushes in H{sub PEG}-U-poly(NIPAAm) are uniformly dispersed throughout the whole hydrogel network. Successful preparation of H{sub PEG}-S-poly(NIPAAm), H{sub PEG}-G-poly(NIPAAm) and H{sub PEG}-U-poly(NIPAAm) were ascertained by X-ray photoelectron spectroscopy (XPS) and water contact angle measurement. Hence, the flexibility and controllability of the synthetic strategy in varying the distribution of polymer brushes and hydrogel surface properties was demonstrated. Hydrogels with tunable and well-defined 3-dimensional poly(NIPAAm) polymer brushes could be tailor-designed to find potential applications in smart devices or skin dressing, such as for diabetics

Sensitivity improvement of a fibre Bragg grating pH sensor with elastomeric coating

Science.gov (United States)

Yulianti, Ian; Supa'at, A. S. M.; Idrus, Sevia M.; Kurdi, Ojo; Anwar, M. R. S.

2012-01-01

A new optical pH sensor based on fibre Bragg grating (FBG) is demonstrated. The sensor consists of a FBG coated with pH sensitive hydrogel. The sensing was performed through the detection of wavelength shifts resulting from the induced strain on the FBG due to mechanical expansion of the hydrogel. An elastomeric coating was applied before the hydrogel coating to improve the sensitivity. The sensor performance was investigated by simulating the hydrogel swelling and the strain induced on the FBG. The swelling of hydrogel due to pH change was modelled using a free-energy function and was solved using the finite element method. With silicone rubber as the elastomer material, the results show that the sensitivity was improved by up to 66% compared to that of the FBG pH sensor without elastomeric coating.

Sensitivity improvement of a fibre Bragg grating pH sensor with elastomeric coating

International Nuclear Information System (INIS)

Yulianti, Ian; Supa'at, A S M; Idrus, Sevia M; Anwar, M R S; Kurdi, Ojo

2012-01-01

A new optical pH sensor based on fibre Bragg grating (FBG) is demonstrated. The sensor consists of a FBG coated with pH sensitive hydrogel. The sensing was performed through the detection of wavelength shifts resulting from the induced strain on the FBG due to mechanical expansion of the hydrogel. An elastomeric coating was applied before the hydrogel coating to improve the sensitivity. The sensor performance was investigated by simulating the hydrogel swelling and the strain induced on the FBG. The swelling of hydrogel due to pH change was modelled using a free-energy function and was solved using the finite element method. With silicone rubber as the elastomer material, the results show that the sensitivity was improved by up to 66% compared to that of the FBG pH sensor without elastomeric coating

Antifouling properties of hydrogels

International Nuclear Information System (INIS)

Murosaki, Takayuki; Gong, Jian Ping; Ahmed, Nafees

2011-01-01

Marine sessile organisms easily adhere to submerged solids such as rocks, metals and plastics, but not to seaweeds and fishes, which are covered with soft and wet 'hydrogel'. Inspired by this fact, we have studied long-term antifouling properties of hydrogels against marine sessile organisms. Hydrogels, especially those containing hydroxy group and sulfonic group, show excellent antifouling activity against barnacles both in laboratory assays and in the marine environment. The extreme low settlement on hydrogels in vitro and in vivo is mainly caused by antifouling properties against the barnacle cypris. (topical review)

Antifouling properties of hydrogels

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Takayuki Murosaki, Nafees Ahmed and Jian Ping Gong

2011-01-01

Full Text Available Marine sessile organisms easily adhere to submerged solids such as rocks, metals and plastics, but not to seaweeds and fishes, which are covered with soft and wet 'hydrogel'. Inspired by this fact, we have studied long-term antifouling properties of hydrogels against marine sessile organisms. Hydrogels, especially those containing hydroxy group and sulfonic group, show excellent antifouling activity against barnacles both in laboratory assays and in the marine environment. The extreme low settlement on hydrogels in vitro and in vivo is mainly caused by antifouling properties against the barnacle cypris.

Foamed oligo(poly(ethylene glycol)fumarate) hydrogels as versatile prefabricated scaffolds for tissue engineering.

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Henke, Matthias; Baumer, Julia; Blunk, Torsten; Tessmar, Joerg

2014-03-01

Radically cross-linked hydrogels are frequently used as cell carriers due to their excellent biocompatibility and their tissue-like mechanical properties. Through frequent investigation, PEG-based polymers such as oligo(poly(ethylene glycol)fumarate [OPF] have proven to be especially suitable as cell carriers by encapsulating cells during hydrogel formation. In some cases, NaCl or biodegradable gelatin microparticles were added prior to cross-linking in order to provide space for the proliferating cells, which would otherwise stay embedded in the hydrogel matrix. However, all of these immediate cross-linking procedures involve time consuming sample preparation and sterilization directly before cell culture and often show notable swelling after their preparation. In this study, ready to use OPF-hydrogel scaffolds were prepared by gas foaming, freeze drying, individual packing into bags and subsequent γ-sterilization. The scaffolds could be stored and used "off-the-shelf" without any need for further processing prior to cell culture. Thus the handling was simplified and the sterility of the cell carrier was assured. Further improvement of the gel system was achieved using a two component injectable system, which may be used for homogenous injection molding in order to create individually shaped three dimensional scaffolds. In order to evaluate the suitability of the scaffolds for tissue engineering, constructs were seeded with juvenile bovine chondrocytes and cultured for 28 days. Cross-sections of the respective constructs showed an intense and homogenous red staining of GAG with safranin O, indicating a homogenous cell distribution within the scaffolds and the production of substantial amounts of GAG-rich matrix. Copyright © 2012 John Wiley & Sons, Ltd.

Sustained Delivery of Chondroitinase ABC from Hydrogel System

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Filippo Rossi

2012-03-01

Full Text Available In the injured spinal cord, chondroitin sulfate proteoglycans (CSPGs are the principal responsible of axon growth inhibition and they contribute to regenerative failure, promoting glial scar formation. Chondroitinase ABC (chABC is known for being able to digest proteoglycans, thus degrading glial scar and favoring axonal regrowth. However, its classic administration is invasive, infection-prone and clinically problematic. An agarose-carbomer (AC1 hydrogel, already used in SCI repair strategies, was here investigated as a delivery system capable of an effective chABC administration: the material ability to include chABC within its pores and the possibility to be injected into the target tissue were firstly proved. Subsequently, release kinetic and the maintenance of enzymatic activity were positively assessed: AC1 hydrogel was thus confirmed to be a feasible tool for chABC delivery and a promising device for spinal cord injury topic repair strategies.

Towards a quantitative understanding of oxygen tension and cell density evolution in fibrin hydrogels.

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Demol, Jan; Lambrechts, Dennis; Geris, Liesbet; Schrooten, Jan; Van Oosterwyck, Hans

2011-01-01

The in vitro culture of hydrogel-based constructs above a critical size is accompanied by problems of unequal cell distribution when diffusion is the primary mode of oxygen transfer. In this study, an experimentally-informed mathematical model was developed to relate cell proliferation and death inside fibrin hydrogels to the local oxygen tension in a quantitative manner. The predictive capacity of the resulting model was tested by comparing its outcomes to the density, distribution and viability of human periosteum derived cells (hPDCs) that were cultured inside fibrin hydrogels in vitro. The model was able to reproduce important experimental findings, such as the formation of a multilayered cell sheet at the hydrogel periphery and the occurrence of a cell density gradient throughout the hydrogel. In addition, the model demonstrated that cell culture in fibrin hydrogels can lead to complete anoxia in the centre of the hydrogel for realistic values of oxygen diffusion and consumption. A sensitivity analysis also identified these two parameters, together with the proliferation parameters of the encapsulated cells, as the governing parameters for the occurrence of anoxia. In conclusion, this study indicates that mathematical models can help to better understand oxygen transport limitations and its influence on cell behaviour during the in vitro culture of cell-seeded hydrogels. Copyright © 2010 Elsevier Ltd. All rights reserved.

Hydrogel nanoparticles in drug delivery.

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Hamidi, Mehrdad; Azadi, Amir; Rafiei, Pedram

2008-12-14

Hydrogel nanoparticles have gained considerable attention in recent years as one of the most promising nanoparticulate drug delivery systems owing to their unique potentials via combining the characteristics of a hydrogel system (e.g., hydrophilicity and extremely high water content) with a nanoparticle (e.g., very small size). Several polymeric hydrogel nanoparticulate systems have been prepared and characterized in recent years, based on both natural and synthetic polymers, each with its own advantages and drawbacks. Among the natural polymers, chitosan and alginate have been studied extensively for preparation of hydrogel nanoparticles and from synthetic group, hydrogel nanoparticles based on poly (vinyl alcohol), poly (ethylene oxide), poly (ethyleneimine), poly (vinyl pyrrolidone), and poly-N-isopropylacrylamide have been reported with different characteristics and features with respect to drug delivery. Regardless of the type of polymer used, the release mechanism of the loaded agent from hydrogel nanoparticles is complex, while resulting from three main vectors, i.e., drug diffusion, hydrogel matrix swelling, and chemical reactivity of the drug/matrix. Several crosslinking methods have been used in the way to form the hydrogel matix structures, which can be classified in two major groups of chemically- and physically-induced crosslinking.

Open loop, auto reversing liquid nitrogen circulation thermal system for thermo vacuum chamber

International Nuclear Information System (INIS)

Naidu, M C A; Nolakha, Dinesh; Saharkar, B S; Kavani, K M; Patel, D R

2012-01-01

In a thermo vacuum chamber, attaining and controlling low and high temperatures (-100 Deg. C to +120 Deg. C) is a very important task. This paper describes the development of 'Open loop, auto reversing liquid nitrogen based thermal system'. System specifications, features, open loop auto reversing system, liquid nitrogen flow paths etc. are discussed in this paper. This thermal system consists of solenoid operated cryogenic valves, double embossed thermal plate (shroud), heating elements, temperature sensors and PLC. Bulky items like blowers, heating chambers, liquid nitrogen injection chambers, huge pipe lines and valves were not used. This entire thermal system is very simple to operate and PLC based, fully auto system with auto tuned to given set temperatures. This system requires a very nominal amount of liquid nitrogen (approx. 80 liters / hour) while conducting thermo vacuum tests. This system was integrated to 1.2m dia thermo vacuum chamber, as a part of its augmentation, to conduct extreme temperature cycling tests on passive antenna reflectors of satellites.

A comparative study of graphene-hydrogel hybrid bionanocomposites for biosensing.

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Burrs, S L; Vanegas, D C; Rong, Y; Bhargava, M; Mechulan, N; Hendershot, P; Yamaguchi, H; Gomes, C; McLamore, E S

2015-03-07

Hydrogels have become increasingly popular as immobilization materials for cells, enzymes and proteins for biosensing applications. Enzymatic biosensors that utilize hydrogel as an encapsulant have shown improvements over other immobilization techniques such as cross linking and covalent bonding. However, to date there are no studies which directly compare multiple hydrogel-graphene nanocomposites using the same enzyme and test conditions. This study compares the performance of four different hydrogels used as protein encapsulants in a mediator-free biosensor based on graphene-nanometal-enzyme composites. Alcohol oxidase (AOx) was encapsulated in chitosan poly-N-isopropylacrylamide (PNIPAAM), silk fibroin or cellulose nanocrystals (CNC) hydrogels, and then spin coated onto a nanoplatinum-graphene modified electrode. The transduction mechanism for the biosensor was based on AOx-catalyzed oxidation of methanol to produce hydrogen peroxide. To isolate the effect(s) of stimulus response on biosensor behavior, all experiments were conducted at 25 °C and pH 7.10. Electroactive surface area (ESA), electrochemical impedance spectroscopy (EIS), sensitivity to methanol, response time, limit of detection, and shelf life were measured for each bionanocomposite. Chitosan and PNIPAAM had the highest sensitivity (0.46 ± 0.2 and 0.3 ± 0.1 μA mM(-1), respectively) and electroactive surface area (0.2 ± 0.06 and 0.2 ± 0.02 cm(2), respectively), as well as the fastest response time (4.3 ± 0.8 and 4.8 ± 1.1 s, respectively). Silk and CNC demonstrated lower sensitivity (0.09 ± 0.02 and 0.15 ± 0.03 μA mM(-1), respectively), lower electroactive surface area (0.12 ± 0.02 and 0.09 ± 0.03 cm(2), respectively), and longer response time (8.9 ± 2.1 and 6.3 ± 0.8 s, respectively). The high porosity of chitosan, PNIPAAM, and silk gels led to excellent transport, which was significantly better than CNC bionanocomposites. Electrochemical performance of CNC bionanocomposites were

Metabolic Study of Cancer Cells Using a pH Sensitive Hydrogel Nanofiber Light Addressable Potentiometric Sensor.

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Shaibani, Parmiss Mojir; Etayash, Hashem; Naicker, Selvaraj; Kaur, Kamaljit; Thundat, Thomas

2017-01-27

We report a simple, fast, and cost-effective approach that measures cancer cell metabolism and their response to anticancer drugs in real time. Using a Light Addressable Potentiometric Sensor integrated with pH sensitive hydrogel nanofibers (NF-LAPS), we detect localized changes in pH of the media as cancer cells consume glucose and release lactate. NF-LAPS shows a sensitivity response of 74 mV/pH for cancer cells. Cancer cells (MDA MB231) showed a response of ∼0.4 unit change in pH compared to virtually no change observed for normal cells (MCF10A). We also observed a drop in pH for the multidrug-resistant cancer cells (MDA-MB-435MDR) in the presence of doxorubicin. However, inhibition of the metabolic enzymes such as hexokinase and lactate dehydrogenase-A suggested an improvement in the efficacy of doxorubicin by decreasing the level of acidification. This approach, based on extracellular acidification, enhances our understanding of cancer cell metabolic modes and their response to chemotherapies, which will help in the development of better treatments, including choice of drugs and dosages.

Tough and Conductive Hybrid Hydrogels Enabling Facile Patterning.

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Zhu, Fengbo; Lin, Ji; Wu, Zi Liang; Qu, Shaoxing; Yin, Jun; Qian, Jin; Zheng, Qiang

2018-04-25

Conductive polymer hydrogels (CPHs) that combine the unique properties of hydrogels and electronic properties of conductors have shown their great potentials in wearable/implantable electronic devices, where materials with remarkable mechanical properties, high conductivity, and easy processability are demanding. Here, we have developed a new type of polyion complex/polyaniline (PIC/PAni) hybrid hydrogels that are tough, conductive, and can be facilely patterned. The incorporation of conductive phase (PAni) into PIC matrix through phytic acid resulted in hybrid gels with ∼65 wt % water; high conductivity while maintaining the key viscoelasticity of the tough matrix. The gel prepared from 1 M aniline (Ani) exhibited the breaking strain, fracture stress, tensile modulus, and electrical conductivity of 395%, 1.15 MPa, 5.31 MPa, and 0.7 S/m, respectively, superior to the most existing CPHs. The mechanical and electrical performance of PIC/PAni hybrid hydrogels exhibited pronounced rate-dependent and self-recovery behaviors. The hybrid gels can effectively detect subtle human motions as strain sensors. Alternating conductive/nonconductive patterns can be readily achieved by selective Ani polymerization using stencil masks. This facile patterning method based on PIC/PAni gels can be readily scaled up for fast fabrication of wavy gel circuits and multichannel sensor arrays, enabling real-time monitoring of the large-extent and large-area deformations with various sensitivities.

Photobiomodulation of mesenchymal stem cells encapsulated in an injectable rhBMP4-loaded hydrogel directs hard tissue bioengineering.

Science.gov (United States)

Diniz, Ivana M A; Carreira, Ana C O; Sipert, Carla R; Uehara, Cindi M; Moreira, Maria S N; Freire, Laila; Pelissari, Cibele; Kossugue, Patrícia M; de Araújo, Daniele R; Sogayar, Mari C; Marques, Márcia M

2018-06-01

Photobiomodulation (PBM) therapy displays relevant properties for tissue healing and regeneration, which may be of interest for the tissue engineering field. Here, we show that PBM is able to improve cell survival and to interact with recombinant human Bone Morphogenetic Protein 4 (rhBMP4) to direct and accelerate odonto/osteogenic differentiation of dental derived mesenchymal stem cells (MSCs). MSCs were encapsulated in an injectable and thermo-responsive cell carrier (Pluronic ® F-127) loaded with rhBMP4 and then photoactivated. PBM improved MSCs self-renewal and survival upon encapsulation in the Pluronic ® F-127. In the presence of rhBMP4, cell odonto/osteogenic differentiation was premature and markedly improved in the photoactivated MSCs. An in vivo calvarial critical sized defect model demonstrated significant increase in bone formation after PBM treatment. Finally, a balance in the reactive oxygen species levels may be related to the favorable results of PBM and rhBMP4 association. PBM may act in synergism with rhBMP4 and is a promise candidate to direct and accelerate hard tissue bioengineering. © 2017 Wiley Periodicals, Inc.

Tertiary-amine-containing thermo- and pH-sensitive hydrophilic ABA triblock copolymers: effect of different tertiary amines on thermally induced sol-gel transitions.

Science.gov (United States)

Henn, Daniel M; Wright, Roger A E; Woodcock, Jeremiah W; Hu, Bin; Zhao, Bin

2014-03-11

This Article reports on the synthesis of a series of well-defined, tertiary-amine-containing ABA triblock copolymers, composed of a poly(ethylene oxide) (PEO) central block and thermo- and pH-sensitive outer blocks, and the study of the effect of different tertiary amines on thermally induced sol-gel transition temperatures (T(sol-gel)) of their 10 wt % aqueous solutions. The doubly responsive ABA triblock copolymers were prepared from a difunctional PEO macroinitiator by atom transfer radical polymerization of methoxydi(ethylene glycol) methacrylate and ethoxydi(ethylene glycol) methacrylate at a feed molar ratio of 30:70 with ∼5 mol % of either N,N-diethylaminoethyl methacrylate (DEAEMA), N,N-diisopropylaminoethyl methacrylate, or N,N-di(n-butyl)aminoethyl methacrylate. The chain lengths of thermosensitive outer blocks and the molar contents of tertiary amines were very similar for all copolymers. Using rheological measurements, we determined the pH dependences of T(sol-gel) of 10 wt % aqueous solutions of these copolymers in a phosphate buffer. The T(sol-gel) versus pH curves of all polymers exhibited a sigmoidal shape. The T(sol-gel) increased with decreasing pH; the changes were small on both high and low pH sides. At a specific pH, the T(sol-gel) decreased with increasing the hydrophobicity of the tertiary amine, and upon decreasing pH the onset pH value for the T(sol-gel) to begin to increase noticeably was lower for the more hydrophobic tertiary amine-containing copolymer. In addition, we studied the effect of different tertiary amines on the release behavior of FITC-dextran from 10 wt % micellar gels in an acidic medium at 37 and 27 °C. The release profiles for three studied hydrogels at 37 °C were essentially the same, suggesting that the release was dominated by the diffusion of FITC-dextran. At 27 °C, the release was significantly faster for the DEAEMA-containing copolymer, indicating that both diffusion and gel dissolution contributed to the

The Formation Mechanism of Hydrogels.

Science.gov (United States)

Lu, Liyan; Yuan, Shiliang; Wang, Jing; Shen, Yun; Deng, Shuwen; Xie, Luyang; Yang, Qixiang

2017-06-12

Hydrogels are degradable polymeric networks, in which cross-links play a vital role in structure formation and degradation. Cross-linking is a stabilization process in polymer chemistry that leads to the multi-dimensional extension of polymeric chains, resulting in network structures. By cross-linking, hydrogels are formed into stable structures that differ from their raw materials. Generally, hydrogels can be prepared from either synthetic or natural polymers. Based on the types of cross-link junctions, hydrogels can be categorized into two groups: the chemically cross-linked and the physically cross-linked. Chemically cross-linked gels have permanent junctions, in which covalent bonds are present between different polymer chains, thus leading to excellent mechanical strength. Although chemical cross-linking is a highly resourceful method for the formation of hydrogels, the cross-linkers used in hydrogel preparation should be extracted from the hydrogels before use, due to their reported toxicity, while, in physically cross-linked gels, dissolution is prevented by physical interactions, such as ionic interactions, hydrogen bonds or hydrophobic interactions. Physically cross-linked methods for the preparation of hydrogels are the alternate solution for cross-linker toxicity. Both methods will be discussed in this essay. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Laminin Peptide-Immobilized Hydrogels Modulate Valve Endothelial Cell Hemostatic Regulation.

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Liezl Rae Balaoing

Full Text Available Valve endothelial cells (VEC have unique phenotypic responses relative to other types of vascular endothelial cells and have highly sensitive hemostatic functions affected by changes in valve tissues. Furthermore, effects of environmental factors on VEC hemostatic function has not been characterized. This work used a poly(ethylene glycol diacrylate (PEGDA hydrogel platform to evaluate the effects of substrate stiffness and cell adhesive ligands on VEC phenotype and expression of hemostatic genes. Hydrogels of molecular weights (MWs 3.4, 8, and 20 kDa were polymerized into platforms of different rigidities and thiol-modified cell adhesive peptides were covalently bound to acrylate groups on the hydrogel surfaces. The peptide RKRLQVQLSIRT (RKR is a syndecan-1 binding ligand derived from laminin, a trimeric protein and a basement membrane matrix component. Conversely, RGDS is an integrin binding peptide found in many extracellular matrix (ECM proteins including fibronectin, fibrinogen, and von Willebrand factor (VWF. VECs adhered to and formed a stable monolayer on all RKR-coated hydrogel-MW combinations. RGDS-coated platforms supported VEC adhesion and growth on RGDS-3.4 kDa and RGDS-8 kDa hydrogels. VECs cultured on the softer RKR-8 kDa and RKR-20 kDa hydrogel platforms had significantly higher gene expression for all anti-thrombotic (ADAMTS-13, tissue factor pathway inhibitor, and tissue plasminogen activator and thrombotic (VWF, tissue factor, and P-selectin proteins than VECs cultured on RGDS-coated hydrogels and tissue culture polystyrene controls. Stimulated VECs promoted greater platelet adhesion than non-stimulated VECs on their respective culture condition; yet stimulated VECs on RGDS-3.4 kDa gels were not as responsive to stimulation relative to the RKR-gel groups. Thus, the syndecan binding, laminin-derived peptide promoted stable VEC adhesion on the softer hydrogels and maintained VEC phenotype and natural hemostatic function. In

Genipin-cross-linked poly(L-lysine)-based hydrogels: synthesis, characterization, and drug encapsulation.

Science.gov (United States)

Wang, Steven S S; Hsieh, Ping-Lun; Chen, Pei-Shan; Chen, Yu-Tien; Jan, Jeng-Shiung

2013-11-01

Genipin-cross-linked hydrogels composed of biodegradable and pH-sensitive cationic poly(L-lysine) (PLL), poly(L-lysine)-block-poly(L-alanine) (PLL-b-PLAla), and poly(L-lysine)-block-polyglycine (PLL-b-PGly) polypeptides were synthesized, characterized, and used as carriers for drug delivery. These polypeptide hydrogels can respond to pH-stimulus and their gelling and mechanical properties, degradation rate, and drug release behavior can be tuned by varying polypeptide composition and cross-linking degree. Comparing with natural polymers, the synthetic polypeptides with well-defined chain length and composition can warrant the preparation of the hydrogels with tunable properties to meet the criteria for specific biomedical applications. These hydrogels composed of natural building blocks exhibited good cell compatibility and enzyme degradability and can support cell attachment/proliferation. The evaluation of these hydrogels for in vitro drug release revealed that the controlled release profile was a biphasic pattern with a mild burst release and a moderate release rate thereafter, suggesting the drug molecules were encapsulated inside the gel matrix. With the versatility of polymer chemistry and conjugation of functional moieties, it is expected these hydrogels can be useful for biomedical applications such as polymer therapeutics and tissue engineering. Copyright © 2013 Elsevier B.V. All rights reserved.

Alginate-Collagen Fibril Composite Hydrogel

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Mahmoud Baniasadi

2015-02-01

Full Text Available We report on the synthesis and the mechanical characterization of an alginate-collagen fibril composite hydrogel. Native type I collagen fibrils were used to synthesize the fibrous composite hydrogel. We characterized the mechanical properties of the fabricated fibrous hydrogel using tensile testing; rheometry and atomic force microscope (AFM-based nanoindentation experiments. The results show that addition of type I collagen fibrils improves the rheological and indentation properties of the hydrogel.

Biocompatible and bioadhesive hydrogels based on 2-hydroxyethyl methacrylate, monofunctional poly(alkylene glycols and itaconic acid

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Mićić Maja M.

2007-01-01

Full Text Available New types of hydrogels were prepared by the radical copolymerization of 2-hydroxyethyl methacrylate, itaconic acid and four different poly(alkylene glycol (methacrylate components (Bisomers in a water/ethanol mixture as solvent. The polymers swell in water at 25°C to yield homogeneous transparent hydrogels. All the hydrogels displayed pH sensitive behavior in buffers of the pH range from 2.20 to 7.40, under conditions similar to those of biological fluids. The presence of these two comonomers, which were added to HEMA, increased the swelling degree of the hydrogels and gave gels with better elasticity. The hydrogels were thermally stable in the vicinity of the physiological temperature (37°C. The copolymer containing pure poly(ethylene glycol acrylate units generally had the best properties. The tests performed on the hydrogels confirmed that they were neither hemolytic nor cytotoxic. The copolymer samples showed better cell viability and less hemolytic activity than the PHEMA sample, confirming the assumption that poly(alkylene glycols improve the biocompatibility of hydrogels. Due to their swelling and mechanical characteristics, as well as the very good biocompatibility and bioadhesive properties, poly(Bisomer/HEMA/IA hydrogels are promising for utilization in the field of biomedicals, especially for the controlled release of drugs.