Conjugated polymer nanoparticles, methods of using, and methods of making

KAUST Repository

Habuchi, Satoshi; Piwonski, Hubert Marek; Michinobu, Tsuyoshi

2017-01-01

Embodiments of the present disclosure provide for conjugated polymer nanoparticle, method of making conjugated polymer nanoparticles, method of using conjugated polymer nanoparticle, polymers, and the like.

Conjugated polymer nanoparticles, methods of using, and methods of making

KAUST Repository

Habuchi, Satoshi

2017-03-16

Embodiments of the present disclosure provide for conjugated polymer nanoparticle, method of making conjugated polymer nanoparticles, method of using conjugated polymer nanoparticle, polymers, and the like.

Integrated circuits based on conjugated polymer monolayer.

Science.gov (United States)

Li, Mengmeng; Mangalore, Deepthi Kamath; Zhao, Jingbo; Carpenter, Joshua H; Yan, Hongping; Ade, Harald; Yan, He; Müllen, Klaus; Blom, Paul W M; Pisula, Wojciech; de Leeuw, Dago M; Asadi, Kamal

2018-01-31

It is still a great challenge to fabricate conjugated polymer monolayer field-effect transistors (PoM-FETs) due to intricate crystallization and film formation of conjugated polymers. Here we demonstrate PoM-FETs based on a single monolayer of a conjugated polymer. The resulting PoM-FETs are highly reproducible and exhibit charge carrier mobilities reaching 3 cm 2  V -1  s -1 . The high performance is attributed to the strong interactions of the polymer chains present already in solution leading to pronounced edge-on packing and well-defined microstructure in the monolayer. The high reproducibility enables the integration of discrete unipolar PoM-FETs into inverters and ring oscillators. Real logic functionality has been demonstrated by constructing a 15-bit code generator in which hundreds of self-assembled PoM-FETs are addressed simultaneously. Our results provide the state-of-the-art example of integrated circuits based on a conjugated polymer monolayer, opening prospective pathways for bottom-up organic electronics.

Conjugated Polymers for Flexible Energy Harvesting and Storage.

Science.gov (United States)

Zhang, Zhitao; Liao, Meng; Lou, Huiqing; Hu, Yajie; Sun, Xuemei; Peng, Huisheng

2018-03-01

Since the discovery of conjugated polymers in the 1970s, they have attracted considerable interest in light of their advantages of having a tunable bandgap, high electroactivity, high flexibility, and good processability compared to inorganic conducting materials. The above combined advantages make them promising for effective energy harvesting and storage, which have been widely studied in recent decades. Herein, the key advancements in the use of conjugated polymers for flexible energy harvesting and storage are reviewed. The synthesis, structure, and properties of conjugated polymers are first summarized. Then, their applications in flexible polymer solar cells, thermoelectric generators, supercapacitors, and lithium-ion batteries are described. The remaining challenges are then discussed to highlight the future direction in the development of conjugated polymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Recent Advances in Conjugated Polymers for Light Emitting Devices

Science.gov (United States)

AlSalhi, Mohamad Saleh; Alam, Javed; Dass, Lawrence Arockiasamy; Raja, Mohan

2011-01-01

A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review. PMID:21673938

Polymers in Carbon Dots: A Review

Directory of Open Access Journals (Sweden)

Yiqun Zhou

2017-02-01

Full Text Available Carbon dots (CDs have been widely studied since their discovery in 2004 as a green substitute of the traditional quantum dots due to their excellent photoluminescence (PL and high biocompatibility. Meanwhile, polymers have increasingly become an important component for both synthesis and modification of CDs to provide polymeric matrix and enhance their PL property. Furthermore, critical analysis of composites of CDs and polymers has not been available. Herein, in this review, we summarized the use of polymers in the synthesis and functionalization of CDs, and the applications of these CDs in various fields.

Conjugated Polymer Solar Cells

National Research Council Canada - National Science Library

Paraschuk, Dmitry Y

2006-01-01

This report results from a contract tasking Moscow State University as follows: Conjugated polymers are promising materials for many photonics applications, in particular, for photovoltaic and solar cell devices...

Bis-polymer lipid-peptide conjugates and nanoparticles thereof

Energy Technology Data Exchange (ETDEWEB)

Xu, Ting; Dong, He; Shu, Jessica; Dube, Nikhil

2018-04-24

The present invention provides bis-polymer lipid-peptide conjugates containing a hydrophobic block and headgroup containing a helical peptide and two polymer blocks. The conjugates can self-assemble to form helix bundle subunits, which in turn assemble to provide micellar nanocarriers for drug cargos and other agents. Particles containing the conjugates and methods for forming the particles are also disclosed.

Quantum dot doped solid polymer electrolyte for device application

Energy Technology Data Exchange (ETDEWEB)

Singh, Pramod K.; Kim, Kang Wook; Rhee, Hee-Woo [Department of Chemical and Biomolecular Engineering, Sogang University, Mapo-Gu, Seoul 121-742 (Korea)

2009-06-15

ZnS capped CdSe quantum dots embedded in PEO:KI:I{sub 2} polymer electrolyte matrix have been synthesized and characterized for dye sensitized solar cell (DSSC) application. The complex impedance spectroscopy shows enhance in ionic conductivity ({sigma}) due to charges provide by quantum dots (QD) while AFM affirm the uniform distribution of QD into polymer electrolyte matrix. Cyclic voltammetry revealed the possible interaction between polymer electrolyte, QD and iodide/iodine. The photovoltaic performances of the DSSC containing quantum dots doped polymer electrolyte was also found to improve. (author)

The influence of bio-conjugation on photoluminescence of CdSe/ZnS quantum dots

Energy Technology Data Exchange (ETDEWEB)

Torchynska, Tetyana V. [ESFM Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional, México, D.F. 07738 (Mexico); Vorobiev, Yuri V. [Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV) Querétaro, Libramiento Norponiente 2000, Fracc. Real de Juriquilla, 76230 Querétaro (Mexico); Makhniy, Victor P. [Yuri Fedkovych Chernivtsi National University, 2 Kotsyubynsky Str., 58012 Chernivtsi (Ukraine); Horley, Paul P., E-mail: paul.horley@cimav.edu.mx [Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Chihuahua/Monterrey, 120 Avenida Miguel de Cervantes, 31109 Chihuahua (Mexico)

2014-11-15

We report a considerable blue shift in the luminescence spectra of CdSe/ZnS quantum dots conjugated to anti-interleukin-10 antibodies. This phenomenon can be explained theoretically by accounting for bio-conjugation as a process causing electrostatic interaction between a quantum dot and an antibody, which reduces effective volume of the dot core. To solve the Schrödinger equation for an exciton confined in the quantum dot, we use mirror boundary conditions that were successfully tested for different geometries of quantum wells.

Single domain antibody–quantum dot conjugates for ricin detection by both fluoroimmunoassay and surface plasmon resonance

Energy Technology Data Exchange (ETDEWEB)

Anderson, George P. [Center for Bio/Molecular Science and Engineering, Code 6900, U. S. Naval Research Laboratory, 4555 Overlook Ave. S.W., Washington, DC 20375 (United States); Glaven, Richard H. [Nova Research, Inc., 1900 Elkin Street, Suite 230, Alexandria, VA 22308 (United States); Algar, W. Russ [Center for Bio/Molecular Science and Engineering, Code 6900, U. S. Naval Research Laboratory, 4555 Overlook Ave. S.W., Washington, DC 20375 (United States); College of Science, George Mason University, Fairfax, VA 22030 (United States); Susumu, Kimihiro [Optical Sciences Division, Code 5600, U. S. Naval Research Laboratory, 4555 Overlook Ave. S.W., Washington, DC 20375 (United States); Sotera Defense Solutions, Annapolis Junction, MD 20701 (United States); Stewart, Michael H. [Optical Sciences Division, Code 5600, U. S. Naval Research Laboratory, 4555 Overlook Ave. S.W., Washington, DC 20375 (United States); Medintz, Igor L. [Center for Bio/Molecular Science and Engineering, Code 6900, U. S. Naval Research Laboratory, 4555 Overlook Ave. S.W., Washington, DC 20375 (United States); Goldman, Ellen R., E-mail: ellen.goldman@nrl.navy.mil [Center for Bio/Molecular Science and Engineering, Code 6900, U. S. Naval Research Laboratory, 4555 Overlook Ave. S.W., Washington, DC 20375 (United States)

2013-07-05

Graphical abstract: -- Highlights: •Anti-ricin single domain antibodies (sdAb) were self-assembled on quantum dots (QDs). •Conjugates were prepared using dihydrolipoic acid-capped CdSe–ZnS core–shell QDs. •The sdAb–QD conjugates functioned in fluoroimmunoassays for ricin detection. •The conjugates provided signal amplification in surface plasmon resonance assays. •Conjugates provided sensitive detection compared to unconjugated sdAb reporters. -- Abstract: The combination of stable biorecognition elements and robust quantum dots (QDs) has the potential to yield highly effective reporters for bioanalyses. Llama-derived single domain antibodies (sdAb) provide small thermostable recognition elements that can be easily manipulated using standard DNA methods. The sdAb was self-assembled on dihydrolipoic acid (DHLA) ligand-capped CdSe–ZnS core–shell QDs made in our laboratory through the polyhistidine tail of the protein, which coordinated to zinc ions on the QD surface. The sdAb–QD bioconjugates were then applied in both fluorometric and surface plasmon resonance (SPR) immunoassays for the detection of ricin, a potential biothreat agent. The sdAb–QD conjugates functioned in fluoroimmunoassays for the detection of ricin, providing equivalent limits of detection when compared to the same anti-ricin sdAb labeled with a conventional fluorophore. In addition, the DHLA-QD–sdAb conjugates were very effective reporter elements in SPR sandwich assays, providing more sensitive detection with a signal enhancement of ∼10-fold over sdAb reporters and 2–4 fold over full sized antibody reporters. Commercially prepared streptavidin-modified polymer-coated QDs also amplified the SPR signal for the detection of ricin when applied to locations where biotinylated anti-ricin sdAb was bound to target; however, we observed a 4-fold greater amplification when using the DHLA-QD–sdAb conjugates in this format.

Single domain antibody–quantum dot conjugates for ricin detection by both fluoroimmunoassay and surface plasmon resonance

International Nuclear Information System (INIS)

Anderson, George P.; Glaven, Richard H.; Algar, W. Russ; Susumu, Kimihiro; Stewart, Michael H.; Medintz, Igor L.; Goldman, Ellen R.

2013-01-01

Graphical abstract: -- Highlights: •Anti-ricin single domain antibodies (sdAb) were self-assembled on quantum dots (QDs). •Conjugates were prepared using dihydrolipoic acid-capped CdSe–ZnS core–shell QDs. •The sdAb–QD conjugates functioned in fluoroimmunoassays for ricin detection. •The conjugates provided signal amplification in surface plasmon resonance assays. •Conjugates provided sensitive detection compared to unconjugated sdAb reporters. -- Abstract: The combination of stable biorecognition elements and robust quantum dots (QDs) has the potential to yield highly effective reporters for bioanalyses. Llama-derived single domain antibodies (sdAb) provide small thermostable recognition elements that can be easily manipulated using standard DNA methods. The sdAb was self-assembled on dihydrolipoic acid (DHLA) ligand-capped CdSe–ZnS core–shell QDs made in our laboratory through the polyhistidine tail of the protein, which coordinated to zinc ions on the QD surface. The sdAb–QD bioconjugates were then applied in both fluorometric and surface plasmon resonance (SPR) immunoassays for the detection of ricin, a potential biothreat agent. The sdAb–QD conjugates functioned in fluoroimmunoassays for the detection of ricin, providing equivalent limits of detection when compared to the same anti-ricin sdAb labeled with a conventional fluorophore. In addition, the DHLA-QD–sdAb conjugates were very effective reporter elements in SPR sandwich assays, providing more sensitive detection with a signal enhancement of ∼10-fold over sdAb reporters and 2–4 fold over full sized antibody reporters. Commercially prepared streptavidin-modified polymer-coated QDs also amplified the SPR signal for the detection of ricin when applied to locations where biotinylated anti-ricin sdAb was bound to target; however, we observed a 4-fold greater amplification when using the DHLA-QD–sdAb conjugates in this format

Lipid-peptide-polymer conjugates and nanoparticles thereof

Science.gov (United States)

Xu, Ting; Dong, He; Shu, Jessica

2015-06-02

The present invention provides a conjugate having a peptide with from about 10 to about 100 amino acids, wherein the peptide adopts a helical structure. The conjugate also includes a first polymer covalently linked to the peptide, and a hydrophobic moiety covalently linked to the N-terminus of the peptide, wherein the hydrophobic moiety comprises a second polymer or a lipid moiety. The present invention also provides helix bundles form by self-assembling the conjugates, and particles formed by self-assembling the helix bundles. Methods of preparing the helix bundles and particles are also provided.

Thiolated polymers: synthesis and in vitro evaluation of polymer-cysteamine conjugates.

Science.gov (United States)

Bernkop-Schnürch, A; Clausen, A E; Hnatyszyn, M

2001-09-11

The purpose of the present study was to synthesize and characterize novel thiolated polymers. Mediated by a carbodiimide cysteamine was covalently linked to sodium carboxymethylcellulose (CMC) and polycarbophil (PCP). The resulting CMC-cysteamine conjugates displayed 77.9+/-6.7 and 365.1+/-8.7 micromol thiol groups per gram of polymer, whereas the PCP-cysteamine conjugates showed 26.3+/-1.9 and 122.7+/-3.8 micromol thiol groups per gram of polymer (mean+/-S.D.; n=3). In aqueous solutions above pH 5.0 both modified polymers were capable of forming inter- and/or intra-molecular disulfide bonds. The reaction velocity of this oxidation process was accelerated with a decrease in the proton concentration. The oxidation proceeded more rapidly within thiolated CMC than within thiolated PCP. Permeation studies carried out in Ussing-type chambers with freshly excised intestinal mucosa from guinea pigs utilizing sodium fluorescein as model drug for the paracellular uptake revealed an enhancement ratio (R=P(app) (conjugate)/P(app) (control)) of 1.15 and 1.41 (mean+/-S.D.; n=3) for the higher thiolated CMC-cysteamine (0.5%; m/v) and PCP-cysteamine conjugate (1.0%; m/v), respectively. The decrease in the transepithelial electrical resistance values was in good correlation with the enhancement ratios. Due to a high crosslinking tendency by the formation of disulfide bonds stabilizing drug carrier systems based on thiolated polymers and a permeation enhancing effect, CMC- and PCP-cysteamine conjugates represent promising excipients for the development of novel drug delivery systems.

Hierarchical assembly of branched supramolecular polymers from (cyclic Peptide)-polymer conjugates.

Science.gov (United States)

Koh, Ming Liang; Jolliffe, Katrina A; Perrier, Sébastien

2014-11-10

We report the synthesis and assembly of (N-methylated cyclic peptide)-polymer conjugates for which the cyclic peptide is attached to either the α- or both α- and ω- end groups of a polymer. A combination of chromatographic, spectroscopic, and scattering techniques reveals that the assembly of the conjugates follows a two-level hierarchy, initially driven by H-bond formation between two N-methylated cyclic peptides, followed by unspecific, noncovalent aggregation of this peptide into small domains that behave as branching points and lead to the formation of branched supramolecular polymers.

Side Chain Engineering in Solution-Processable Conjugated Polymers

KAUST Repository

Mei, Jianguo

2014-01-14

Side chains in conjugated polymers have been primarily utilized as solubilizing groups. However, these side chains have roles that are far beyond. We advocate using side chain engineering to tune a polymer\\'s physical properties, including absorption, emission, energy level, molecular packing, and charge transport. To date, numerous flexible substituents suitable for constructing side chains have been reported. In this Perspective article, we advocate that the side chain engineering approach can advance better designs for next-generation conjugated polymers. © 2013 American Chemical Society.

Conjugated Polymers for Energy Production

DEFF Research Database (Denmark)

Livi, Francesco

This dissertation is aimed at developing materials for flexible, large area, ITO-free polymer solar cells (PSCs) fully printed under ambient conditions. A large screening of conjugated polymers, both novel and well-known materials, has been carried out in order to find suitable candidates...... polymerization method for industrial production of polymers. Several DArP protocols have been employed for the synthesis of PPDTBT leading to polymers with high structural regularity and photovoltaic performances comparable with the same materials synthesized via Stille cross-coupling polymerization...

Bio-degradable highly fluorescent conjugated polymer nanoparticles for bio-medical imaging applications.

Science.gov (United States)

Repenko, Tatjana; Rix, Anne; Ludwanowski, Simon; Go, Dennis; Kiessling, Fabian; Lederle, Wiltrud; Kuehne, Alexander J C

2017-09-07

Conjugated polymer nanoparticles exhibit strong fluorescence and have been applied for biological fluorescence imaging in cell culture and in small animals. However, conjugated polymer particles are hydrophobic and often chemically inert materials with diameters ranging from below 50 nm to several microns. As such, conjugated polymer nanoparticles cannot be excreted through the renal system. This drawback has prevented their application for clinical bio-medical imaging. Here, we present fully conjugated polymer nanoparticles based on imidazole units. These nanoparticles can be bio-degraded by activated macrophages. Reactive oxygen species induce scission of the conjugated polymer backbone at the imidazole unit, leading to complete decomposition of the particles into soluble low molecular weight fragments. Furthermore, the nanoparticles can be surface functionalized for directed targeting. The approach opens a wide range of opportunities for conjugated polymer particles in the fields of medical imaging, drug-delivery, and theranostics.Conjugated polymer nanoparticles have been applied for biological fluorescence imaging in cell culture and in small animals, but cannot readily be excreted through the renal system. Here the authors show fully conjugated polymer nanoparticles based on imidazole units that can be bio-degraded by activated macrophages.

Subgap Absorption in Conjugated Polymers

Science.gov (United States)

Sinclair, M.; Seager, C. H.; McBranch, D.; Heeger, A. J; Baker, G. L.

1991-01-01

Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination.

Degradable conjugated polymers for the selective sorting of semiconducting carbon nanotubes

Science.gov (United States)

Gopalan, Padma; Arnold, Michael Scott; Kansiusarulsamy, Catherine Kanimozhi; Brady, Gerald Joseph; Shea, Matthew John

2018-04-10

Conjugated polymers composed of bi-pyridine units linked to 9,9-dialkyl fluorenyl-2,7-diyl units via imine linkages along the polymer backbone are provided. Also provided are semiconducting single-walled carbon nanotubes coated with the conjugated polymers and methods of sorting and separating s-SWCNTs from a sample comprising a mixture of s-SWCNTs and metallic single-walled carbon nanotubes using the conjugated polymers.

Hemoglobin Detection on a Microfluidic Sensor Chip with a Partially Conjugated Polymer

International Nuclear Information System (INIS)

Eo, Soo Han; Won, Kwang Jae; Song, Simon; Yoon, Bora; Kim, Jong Man

2010-01-01

The development of efficient chemosensors based on the conjugated polymers has been the central focus of a large number of recent research programs. The presence of extensively delocalized electrons and conformational restrictions of the backbone structures make conjugated polymers attractive sensory materials. In these polymers, molecular recognition events influence electronic absorption and emission properties. Thus, a wide variety of conjugated polymer-based sensors have been investigated. However, the majority of the conjugated polymer sensors described to date have been explored in the form of solutions or thin films. Most biologically interesting target molecules, such as proteins, carbohydrates, nucleic acids, or ions, are only soluble in water. Thus, it is desirable to use water-soluble conjugated polymers as sensor matrices. In general, in order to make water-soluble conjugated polymers tedious procedures are required since most synthetic methods developed for this purpose are incompatible with sidechain functionalities. Accordingly, protecting group strategies are required to prepare polymers with requisite functional groups that foster water solubility

Polymer dots grafted TiO2 nanohybrids as high performance visible light photocatalysts.

Science.gov (United States)

Li, Gen; Wang, Feng; Liu, Peng; Chen, Zheming; Lei, Ping; Xu, Zhongshan; Li, Zengxi; Ding, Yanfen; Zhang, Shimin; Yang, Mingshu

2018-04-01

As a new member of carbon dots (CDs), Polymer dots (PDs) prepared by hydrothermal treatment of polymers, usually consist of the carbon core and the connected partially degraded polymer chains. This type of CDs might possess aqueous solubility, non-toxicity, excellent stability against photo-bleaching and high visible light activity. In this research, PDs were prepared by a moderate hydrothermal treatment of polyvinyl alcohol, and PDs grafted TiO 2 (PDs-TiO 2 ) nanohybrids with TiOC bonds were prepared by a facile in-situ hydrothermal treatment of PDs and Ti (SO 4 ) 2 . Under visible light irradiation, the PDs-TiO 2 demonstrate excellent photocatalytic activity for methyl orange degradation, and the photocatalytic rate constant of PDs-TiO 2 is 3.6 and 9.5 times higher than that of pure TiO 2 and commercial P25, respectively. In addition, the PDs-TiO 2 exhibit good recycle stability under UV-Vis light irradiation. The interfacial TiOC bonds and the π-conjugated structures in PDs-TiO 2 can act as the pathways to quickly transfer the excited electrons between PDs and TiO 2 , therefore contribute to the excellent photocatalytic activity. Copyright © 2018 Elsevier Ltd. All rights reserved.

Nanostructured conjugated polymers in chemical sensors: synthesis, properties and applications.

Science.gov (United States)

Correa, D S; Medeiros, E S; Oliveira, J E; Paterno, L G; Mattoso, Luiz C

2014-09-01

Conjugated polymers are organic materials endowed with a π-electron conjugation along the polymer backbone that present appealing electrical and optical properties for technological applications. By using conjugated polymeric materials in the nanoscale, such properties can be further enhanced. In addition, the use of nanostructured materials makes possible miniaturize devices at the micro/nano scale. The applications of conjugated nanostructured polymers include sensors, actuators, flexible displays, discrete electronic devices, and smart fabric, to name a few. In particular, the use of conjugated polymers in chemical and biological sensors is made feasible owning to their sensitivity to the physicochemical conditions of its surrounding environment, such as chemical composition, pH, dielectric constant, humidity or even temperature. Subtle changes in these conditions bring about variations on the electrical (resistivity and capacitance), optical (absorptivity, luminescence, etc.), and mechanical properties of the conjugated polymer, which can be precisely measured by different experimental methods and ultimately associated with a specific analyte and its concentration. The present review article highlights the main features of conjugated polymers that make them suitable for chemical sensors. An especial emphasis is given to nanostructured sensors systems, which present high sensitivity and selectivity, and find application in beverage and food quality control, pharmaceutical industries, medical diagnosis, environmental monitoring, and homeland security, and other applications as discussed throughout this review.

Conjugated Polymers as Actuators: Modes of Actuation

DEFF Research Database (Denmark)

Skaarup, Steen

2004-01-01

The physical and chemical properties of conjugated polymers often depend very strongly on the degree of doping with anions or cations. The movement of ions in and out of the polymer matrix as it is redox cycled is also accompanied by mechanical changes. Both the volume and the stiffness can exhibit...... significant differences between the oxidized and reduced states. These effects form the basis of the use of conjugated polymers as actuators (or “artificial muscles”) controllable by a small (1-10 V) voltage. Three basic modes of actuation (bending, linear extension and stiffness change) have been proposed...

Conjugated polymers as actuators: modes of actuation

DEFF Research Database (Denmark)

Skaarup, Steen

2007-01-01

The physical and chemical properties of conjugated polymers often depend very strongly on the degree of doping with anions or cations. The movement of ions in and out of the polymer matrix as it is redox cycled is also accompanied by mechanical changes. Both the volume and the stiffness can exhibit...... significant differences between the oxidized and reduced states. These effects form the basis of the use of conjugated polymers as actuators (or “artificial muscles”) controllable by a small (1-10 V) voltage. Three basic modes of actuation (bending, linear extension and stiffness change) have been proposed...

Functional Hybrid Biomaterials based on Peptide-Polymer Conjugates for Nanomedicine

Science.gov (United States)

Shu, Jessica Yo

The focus of this dissertation is the design, synthesis and characterization of hybrid functional biomaterials based on peptide-polymer conjugates for nanomedicine. Generating synthetic materials with properties comparable to or superior than those found in nature has been a "holy grail" for the materials community. Man-made materials are still rather simplistic when compared to the chemical and structural complexity of a cell. Peptide-polymer conjugates have the potential to combine the advantages of the biological and synthetic worlds---that is they can combine the precise chemical structure and diverse functionality of biomolecules with the stability and processibility of synthetic polymers. As a new family of soft matter, they may lead to materials with novel properties that have yet to be realized with either of the components alone. In order for peptide-polymer conjugates to reach their full potential as useful materials, the structure and function of the peptide should be maintained upon polymer conjugation. The success in achieving desirable, functional assemblies relies on fundamentally understanding the interactions between each building block and delicately balancing and manipulating these interactions to achieve targeted assemblies without interfering with designed structures and functionalities. Such fundamental studies of peptide-polymer interactions were investigated as the nature of the polymer (hydrophilic vs. hydrophobic) and the site of its conjugation (end-conjugation vs. side-conjugation) were varied. The fundamental knowledge gained was then applied to the design of amphiphiles that self-assemble to form stable functional micelles. The micelles exhibited exceptional monodispersity and long-term stability, which is atypical of self-assembled systems. Thus such micelles based on amphiphilic peptide-polymer conjugates may meet many current demands in nanomedicine, in particular for drug delivery of hydrophobic anti-cancer therapeutics. Lastly

Nanostructured Conjugated Polymers for Energy-Related Applications beyond Solar Cells.

Science.gov (United States)

Xie, Jian; Zhao, Cui-E; Lin, Zong-Qiong; Gu, Pei-Yang; Zhang, Qichun

2016-05-20

To meet the ever-increasing requirements for the next generation of sustainable and versatile energy-related devices, conjugated polymers, which have potential advantages over small molecules and inorganic materials, are among the most promising types of green candidates. The properties of conjugated polymers can be tuned through modification of the structure and incorporation of different functional moieties. In addition, superior performances can be achieved as a result of the advantages of nanostructures, such as their large surface areas and the shortened pathways for charge transfer. Therefore, nanostructured conjugated polymers with different properties can be obtained to be applied in different energy-related organic devices. This review focuses on the application and performance of the recently reported nanostructured conjugated polymers for high-performance devices, including rechargeable lithium batteries, microbial fuel cells (MFCs), thermoelectric generators, and photocatalytic systems. The design strategies, reaction mechanisms, advantages, and limitations of nanostructured conjugated polymers are further discussed in each section. Finally, possible routes to improve the performances of the current systems are also included in the conclusion. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Antibiotic Conjugated Fluorescent Carbon Dots as a Theranostic Agent for Controlled Drug Release, Bioimaging, and Enhanced Antimicrobial Activity

Directory of Open Access Journals (Sweden)

Mukeshchand Thakur

2014-01-01

Full Text Available A novel report on microwave assisted synthesis of bright carbon dots (C-dots using gum arabic (GA and its use as molecular vehicle to ferry ciprofloxacin hydrochloride, a broad spectrum antibiotic, is reported in the present work. Density gradient centrifugation (DGC was used to separate different types of C-dots. After careful analysis of the fractions obtained after centrifugation, ciprofloxacin was attached to synthesize ciprofloxacin conjugated with C-dots (Cipro@C-dots conjugate. Release of ciprofloxacin was found to be extremely regulated under physiological conditions. Cipro@C-dots were found to be biocompatible on Vero cells as compared to free ciprofloxacin (1.2 mM even at very high concentrations. Bare C-dots (∼13 mg mL−1 were used for microbial imaging of the simplest eukaryotic model—Saccharomyces cerevisiae (yeast. Bright green fluorescent was obtained when live imaging was performed to view yeast cells under fluorescent microscope suggesting C-dots incorporation inside the cells. Cipro@C-dots conjugate also showed enhanced antimicrobial activity against both model gram positive and gram negative microorganisms. Thus, the Cipro@C-dots conjugate paves not only a way for bioimaging but also an efficient new nanocarrier for controlled drug release with high antimicrobial activity, thereby serving potential tool for theranostics.

Subgap absorption in conjugated polymers

Energy Technology Data Exchange (ETDEWEB)

Sinclair, M.; Seager, C.H. (Sandia National Labs., Albuquerque, NM (USA)); McBranch, D.; Heeger, A.J. (California Univ., Santa Barbara, CA (USA)); Baker, G.L. (Bell Communications Research, Inc., Red Bank, NJ (USA))

1991-01-01

Along with X{sup (3)}, the magnitude of the optical absorption in the transparent window below the principal absorption edge is an important parameter which will ultimately determine the utility of conjugated polymers in active integrated optical devices. With an absorptance sensitivity of < 10{sup {minus}5}, Photothermal Deflection Spectroscopy (PDS) is ideal for determining the absorption coefficients of thin films of transparent'' materials. We have used PDS to measure the optical absorption spectra of the conjugated polymers poly(1,4-phenylene-vinylene) (and derivitives) and polydiacetylene-4BCMU in the spectral region from 0.55 eV to 3 eV. Our spectra show that the shape of the absorption edge varies considerably from polymer to polymer, with polydiacetylene-4BCMU having the steepest absorption edge. The minimum absorption coefficients measured varied somewhat with sample age and quality, but were typically in the range 1 cm{sup {minus}1} to 10 cm{sup {minus}1}. In the region below 1 eV, overtones of C-H stretching modes were observed, indicating that further improvements in transparency in this spectral region might be achieved via deuteration of fluorination. 11 refs., 4 figs.

Dye linked conjugated homopolymers: using conjugated polymer electroluminescence to optically pump porphyrin-dye emission

DEFF Research Database (Denmark)

Nielsen, K.T.; Spanggaard, H.; Krebs, Frederik C

2004-01-01

. Electroluminescent devices of the homopolymer itself and of the zinc-porphyrin containing polymer were prepared and the nature of the electroluminescence was characterized. The homopolymer segments were found to optically pump the emission of the zinc-porphyrin dye moities. The homopolymer exhibits blue......Zinc-porphyrin dye molecules were incorporated into the backbone of a conjugated polymer material by a method, which allowed for the incorporation of only one zinc-porphyrin dye molecule into the backbone of each conjugated polymer molecule. The electronic properties of the homopolymer were...

Excitons in conjugated polymers: Do we need a paradigma change?

Energy Technology Data Exchange (ETDEWEB)

Beenken, Wichard J.D. [Department of Theoretical Physics I, Ilmenau University of Thechnology (Germany)

2009-12-15

We have previously shown that both, polymer conformation and dynamics are crucial for the exciton transport in conjugated polymers. Thereby we found that the usual Foerster-type hopping transfer model - even if one applies the line-dipole approximation - falls short in one crucial aspect: the nature of the sites the excitons are transferred between is still unclear. We found that the simple model of spectroscopic units defined as segments of the polymer chains separated by structural defects breaking the {pi}-conjugation is only justified for chemical defects like hydrogenated double bonds, or extreme gauche (90 ) torsions between the monomers. Both defects are far too rare in a well-prepared conjugated polymer to explain the mean spectroscopic-unit length of typically 6-7 monomers. Meanwhile, also the concept of dynamical formation of the spectroscopic units, we had previously suggested, has also failed. Thus the question of a paradigma change concerning the exciton transport in conjugated polymers appears on the agenda. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Conjugated polymer photovoltaic devices and materials

International Nuclear Information System (INIS)

Mozer, A.J.; Niyazi, Serdar Sariciftci

2006-01-01

The science and technology of conjugated polymer-based photovoltaic devices (bulk heterojunction solar cells) is highlighted focusing on three major issues, i.e. (i) nano-morphology optimization, (ii) improving charge carrier mobility, (iii) improving spectral sensitivity. Successful strategies towards improved photovoltaic performance are presented using various novel materials, including double-cable polymers, regioregular polymers and low bandgap polymers. The examples presented herein demonstrate that the bulk heterojunction concept is a viable approach towards developing photovoltaic systems by inexpensive solution-based fabrication technologies. (authors)

Molecular design toward highly efficient photovoltaic polymers based on two-dimensional conjugated benzodithiophene.

Science.gov (United States)

Ye, Long; Zhang, Shaoqing; Huo, Lijun; Zhang, Maojie; Hou, Jianhui

2014-05-20

As researchers continue to develop new organic materials for solar cells, benzo[1,2-b:4,5-b']dithiophene (BDT)-based polymers have come to the fore. To improve the photovoltaic properties of BDT-based polymers, researchers have developed and applied various strategies leading to the successful molecular design of highly efficient photovoltaic polymers. Novel polymer materials composed of two-dimensional conjugated BDT (2D-conjugated BDT) have boosted the power conversion efficiency of polymer solar cells (PSCs) to levels that exceed 9%. In this Account, we summarize recent progress related to the design and synthesis of 2D-conjugated BDT-based polymers and discuss their applications in highly efficient photovoltaic devices. We introduce the basic considerations for the construction of 2D-conjugated BDT-based polymers and systematic molecular design guidelines. For example, simply modifying an alkoxyl-substituted BDT to form an alkylthienyl-substituted BDT can improve the polymer hole mobilities substantially with little effect on their molecular energy level. Secondly, the addition of a variety of chemical moieties to the polymer can produce a 2D-conjugated BDT unit with more functions. For example, the introduction of a conjugated side chain with electron deficient groups (such as para-alkyl-phenyl, meta-alkoxyl-phenyl, and 2-alkyl-3-fluoro-thienyl) allowed us to modulate the molecular energy levels of 2D-conjugated BDT-based polymers. Through the rational design of BDT analogues such as dithienobenzodithiophene (DTBDT) or the insertion of larger π bridges, we can tune the backbone conformations of these polymers and modulate their photovoltaic properties. We also discuss the influence of 2D-conjugated BDT on polymer morphology and the blends of these polymers with phenyl-C61 (or C71)-butyric acid methyl ester (PCBM). Finally, we summarize the various applications of the 2D-conjugated BDT-based polymers in highly efficient PSC devices. Overall, this Account

Compact quantum dot-antibody conjugates for FRET immunoassays with subnanomolar detection limits

Science.gov (United States)

Mattera, Lucia; Bhuckory, Shashi; Wegner, K. David; Qiu, Xue; Agnese, Fabio; Lincheneau, Christophe; Senden, Tim; Djurado, David; Charbonnière, Loïc J.; Hildebrandt, Niko; Reiss, Peter

2016-05-01

A novel two-step approach for quantum dot (QD) functionalization and bioconjugation is presented, which yields ultra-compact, stable, and highly luminescent antibody-QD conjugates suitable for use in FRET immunoassays. Hydrophobic InPZnS/ZnSe/ZnS (emission wavelength: 530 nm), CdSe/ZnS (605 nm), and CdSeTe/ZnS (705 nm) QDs were surface functionalized with zwitterionic penicillamine, enabling aqueous phase transfer under conservation of the photoluminescence properties. Post-functionalization with a heterobifunctional crosslinker, containing a lipoic acid group and a maleimide function, enabled the subsequent coupling to sulfhydryl groups of proteins. This was demonstrated by QD conjugation with fragmented antibodies (F(ab)). The obtained F(ab)-QD conjugates range among the smallest antibody-functionalized nanoprobes ever reported, with a hydrodynamic diameter coating for FRET could be demonstrated by an 6.2 and 2.5 fold improvement of the limit of detection (LOD) for PSA compared to commercially available hydrophilic QDs emitting at 605 and 705 nm, respectively. While the commercial QDs contain identical inorganic cores responsible for their fluorescence, they are coated with a comparably thick amphiphilic polymer layer leading to much larger hydrodynamic diameters (>26 nm without biomolecules). The LODs of 0.8 and 3.7 ng mL-1 obtained in 50 μL serum samples are below the clinical cut-off level of PSA (4 ng mL-1) and demonstrate their direct applicability in clinical diagnostics.A novel two-step approach for quantum dot (QD) functionalization and bioconjugation is presented, which yields ultra-compact, stable, and highly luminescent antibody-QD conjugates suitable for use in FRET immunoassays. Hydrophobic InPZnS/ZnSe/ZnS (emission wavelength: 530 nm), CdSe/ZnS (605 nm), and CdSeTe/ZnS (705 nm) QDs were surface functionalized with zwitterionic penicillamine, enabling aqueous phase transfer under conservation of the photoluminescence properties. Post

Non-classical light emission from single conjugated polymers

Science.gov (United States)

Hollars, Christopher; Lane, Stephen; Huser, Thomas

2002-03-01

Photon-antibunching from single, isolated molecules of collapsed-chain poly[2-methoxy,5-(2’-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV) has been observed using confocal microscopy techniques. Efficient inter-segment energy transfer in collapsed-chain conjugated polymers leads to emission from an average of only 2-3 active sites on a polymer chain that is composed of hundreds of quasi-chromophores. These few centers consist of the segments with the lowest excitation energy and are supplied by the efficient light-harvesting and energy transfer of the surrounding higher-energy segments. This effect depends on the conformation of the polymer molecules, which is controlled by solvent polarity. These results provide new insight into the controversial photophysics of conjugated polymers and their application in optoelectronic devices.

Preparation of conjugated polymer suspensions by using ultrasonic atomizer

Energy Technology Data Exchange (ETDEWEB)

Tada, Kazuya, E-mail: tada@eng.u-hyogo.ac.jp; Onoda, Mitsuyoshi

2010-11-30

The electrophoretic deposition is a method useful to prepare conjugated polymer films for electronic devices. This method provides high material recovery rate on the substrate from the suspension, in contrast to the conventional spin-coating in which most of the material placed on the substrate is blown away. Although manual reprecipitation technique successfully yields suspensions of various conjugated polymers including polyfluorene derivatives, it is favorable to control the preparation process of suspensions. In this context, this paper reports preliminary results on the preparation of suspension of conjugated polymer by using an ultrasonic atomizer. While the resultant films do not show particular difference due to the preparation methods of the suspension, the electric current profiles during the electrophoretic deposition suggests that the ultrasonic atomization of polymer solution prior to be mixed with poor solvent results in smaller and less uniform colloidal particles than the conventional manual pouring method.

Preparation and characterization of conjugated polymers made by postpolymerization reactions of alternating polyketones.

Science.gov (United States)

Cheng, Chen; Guironnet, Damien; Barborak, James; Brookhart, Maurice

2011-06-29

Conjugated polymers possessing a poly(2,5-dimethylene-2,5-dihydrofuran) backbone were prepared through postpolymerization reaction of styrenic polyketones with bromine in one-pot reactions. The modification is proposed to proceed via condensation of two repeating units to form a fully characterized polymer with a poly(2,5-dimethylenetetrahydrofuran) backbone. Subsequent bromination and elimination of HBr yield a polymer with a fully conjugated carbon backbone. The new conjugated polymers were characterized by NMR, IR, and UV-vis spectroscopies and by CV. These polymers have strong absorption in the visible region, with the absorption peaks shifted to the NIR region upon doping with acids. The ease of the synthesis of the starting polyketone and of the modifications allows large-scale preparation of those conjugated polymers.

Synthesis of regioregular pentacene-containing conjugated polymers

KAUST Repository

Okamoto, Toshihiro; Jiang, Ying; Becerril, Hector A.; Hong, Sanghyun; Senatore, Michelle L.; Tang, Ming L.; Toney, Michael F.; Siegrist, Theo; Bao, Zhenan

2011-01-01

We report the synthesis and characterization of a new class of regioregular pentacene-containing conjugated polymers via our synthetic routes reported previously. We found that our regioregular pentacene polymers showed improved ordering than their regiorandom counterpart as well as ambipolar OFET performance. © 2011 The Royal Society of Chemistry.

Micelle-like nanoassemblies based on polymer-drug conjugates as an emerging platform for drug delivery.

Science.gov (United States)

Liu, Zhihong; Wang, Yutao; Zhang, Na

2012-07-01

During the past decades, polymer-drug conjugates are one of the hottest topics in novel drug development fields. Amphiphilic polymer-drug conjugates in aqueous solution could form micelles or micelle-like nanoassemblies. Compared with polymer-drug conjugates and the micelles into which drugs are physically entrapped, micelles or micelle-like nanoassemblies based on polymer-drug conjugates bring several additional advantages, including increased drug-loading capacity, enhanced intracellular uptake, reduced systemic toxicity, and improved therapeutic efficacy. This review focuses on recent progress achieved in the research field of micelles or micelle-like nanoassemblies based on polymer-drug conjugates. Firstly, properties of polymers, drugs, and linkers which could be used to build polymer-drug conjugate micelles or micelle-like nanoassemblies are summarized. Then, the characterization methods are described. Finally, the drug-targeting mechanisms are discussed. Micelles or micelle-like nanoassemblies based on polymer-drug conjugates as an emerging platform have the potential to achieve medical treatments with enhanced therapeutic effect. The application of micelles or micelle-like nanoassemblies based on polymer-drug conjugates may give new life to old active compounds abandoned due to their low solubility problems. For clinical application, there is a need to further optimize the properties of the polymer, drug, and linker.

Side Chain Engineering in Solution-Processable Conjugated Polymers

KAUST Repository

Mei, Jianguo; Bao, Zhenan

2014-01-01

Side chains in conjugated polymers have been primarily utilized as solubilizing groups. However, these side chains have roles that are far beyond. We advocate using side chain engineering to tune a polymer's physical properties, including absorption

Photovoltaic Performance of Inverted Polymer Solar Cells Using Hybrid Carbon Quantum Dots and Absorption Polymer Materials

Science.gov (United States)

Lim, Hwain; Lee, Kyu Seung; Liu, Yang; Kim, Hak Yong; Son, Dong Ick

2018-05-01

We report the synthesis and characterization of the carbon quantum dots (C-dots) easily obtained from citric acid and ethanediamine, and also investigated structural, optical and electrical properties. The C-dots have extraordinary optical and electrical features such as absorption of ultraviolet range and effective interface for charge separation and transport in active layer, which make them attractive materials for applications in photovoltaic devices (PV). The C-dots play important roles in charge extraction in the PV structures, they can be synthesized by a simple method and used to insert in active layer of polymer solar cells. In this study, we demonstrate that improve charge transport properties of inverted polymer solar cells (iPSCs) with C-dots and structural, optical and electrical properties of C-dots. As a result, iPSCs with C-dots showed enhancement of more than 30% compared with that of the contrast device in power conversion efficiency.

Thin Films Formed from Conjugated Polymers with Ionic, Water-Soluble Backbones

NARCIS (Netherlands)

Voortman, Thomas P; Chiechi, Ryan C

2015-01-01

This paper compares the morphologies of films of conjugated polymers in which the backbone (main chain) and pendant groups are varied between ionic/hydrophilic and aliphatic/hydrophobic. We observe that conjugated polymers in which the pendant groups and backbone are matched, either ionic-ionic or

Two-dimensional charge transport in self-organized, high-mobility conjugated polymers

DEFF Research Database (Denmark)

Sirringhaus, H.; Brown, P.J.; Friend, R.H.

1999-01-01

Self-organization in many solution-processed, semiconducting conjugated polymers results in complex microstructures, in which ordered microcrystalline domains are embedded in an amorphous matrix(I). This has important consequences for electrical properties of these materials: charge transport...... of the ordered microcrystalline domains in the conjugated polymer poly(3-hexylthiophene), P3HT, Self-organization in P3HT results in a lamella structure with two-dimensional conjugated sheets formed by interchain stacking. We find that, depending on processing conditions, the lamellae can adopt two different...... of polymer transistors in logic circuits(5) and active-matrix displays(4,6)....

Quantum-dots-encoded-microbeads based molecularly imprinted polymer.

Science.gov (United States)

Liu, Yixi; Liu, Le; He, Yonghong; He, Qinghua; Ma, Hui

2016-03-15

Quantum dots encoded microbeads have various advantages such as large surface area, superb optical properties and the ability of multiplexing. Molecularly imprinted polymer that can mimic the natural recognition entities has high affinity and selectivity for the specific analyte. Here, the concept of utilizing the quantum dots encoded microbeads as the supporting material and the polydopamine as the functional monomer to form the core-shell molecular imprinted polymer was proposed for the first time. The resulted imprinted polymer can provide various merits: polymerization can complete in aqueous environment; fabrication procedure is facile and universal; the obvious economic advantage; the thickness of the imprinting layer is highly controllable; polydopamine coating can improve the biocompatibility of the quantum dot encoded microbeads. The rabbit IgG binding and flow cytometer experiment result showed the distinct advantages of this strategy: cost-saving, facile and fast preparation procedure. Most importantly, the ability for the multichannel detection, which makes the imprinted polydopamine modified encoded-beads very attractive in protein pre-concentration, recognition, separation and biosensing. Copyright © 2015 Elsevier B.V. All rights reserved.

Substituted Polyacetylenes Prepared with Rh Catalysts: From Linear to Network-Type Conjugated Polymers

Czech Academy of Sciences Publication Activity Database

Sedláček, J.; Balcar, Hynek

2017-01-01

Roč. 57, č. 1 (2017), s. 31-51 ISSN 1558-3724 Institutional support: RVO:61388955 Keywords : conjugated polymers * polyacetylenes * conjugated polymer networks Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Polymer science Impact factor: 6.459, year: 2016

Synthesis, characterization and target protein binding of drug-conjugated quantum dots in vitro and in living cells

International Nuclear Information System (INIS)

Choi, Youngseon; Kim, Minjung; Cho, Yoojin; Yun, Eunsuk; Song, Rita

2013-01-01

Elucidation of unknown target proteins of a drug is of great importance in understanding cell biology and drug discovery. There have been extensive studies to discover and identify target proteins in the cell. Visualization of targets using drug-conjugated probes has been an important approach to gathering mechanistic information of drug action at the cellular level. As quantum dot (QD) nanocrystals have attracted much attention as a fluorescent probe in the bioimaging area, we prepared drug-conjugated QD to explore the potential of target discovery. As a model drug, we selected a well-known anticancer drug, methotrexate (MTX), which has been known to target dihydrofolate reductase (DHFR) with high affinity binding (K d = 0.54 nM). MTX molecules were covalently attached to amino-PEG-polymer-coated QDs. Specific interactions of MTX-conjugated QDs with DHFR were identified using agarose gel electrophoresis and fluorescence microscopy. Cellular uptake of the MTX-conjugated QDs in living CHO cells was investigated with regard to their localization and distribution pattern. MTX–QD was found to be internalized into the cells via caveolae-medicated endocytosis without significant sequestration in endosomes. A colocalization experiment of the MTX–QD conjugate with antiDHFR-TAT-QD also confirmed that MTX–QD binds to the target DHFR. This study showed the potential of the drug-QD conjugate to identify or visualize drug–target interactions in the cell, which is currently of great importance in the area of drug discovery and chemical biology. (paper)

π-Conjugated polymer anisotropic organogel nanofibrous assemblies for thermoresponsive photonic switches.

Science.gov (United States)

Narasimha, Karnati; Jayakannan, Manickam

2014-11-12

The present work demonstrates one of the first examples of π-conjugated photonic switches (or photonic wave plates) based on the tailor-made π-conjugated polymer anisotropic organogel. New semicrystalline segmented π-conjugated polymers are designed with rigid aromatic oligophenylenevinylene π-core and flexible alkyl chain along the polymer backbone. These polymers are found to be self-assembled as semicrystalline or amorphous with respect to the number of carbon atoms in the alkyl units. These semicrystalline polymers produce organogels having nanofibrous morphology of 20 nm thickness with length up to 5 μm. The polymer organogel is aligned in a narrow glass capillary, and this anisotropic gel device is further demonstrated as photonic switches. The glass capillary device behaves as typical λ/4 photonic wave plates upon the illumination of the plane polarized light. The λ/4 photonic switching ability is found to be maximum at θ = 45° angle under the cross polarizers. The orthogonal arrangements of the gel capillaries produce dark and bright spots as on-and-off optical switches. Thermoreversibility of the polymer organogel (also its xerogel) was exploited to construct thermoresponsive photonic switches for the temperature window starting from 25 to 160 °C. The organic photonic switch concept can be adapted to large number of other π-conjugated materials for optical communication and storage.

Peptide/protein-polymer conjugates: synthetic strategies and design concepts.

Science.gov (United States)

Gauthier, Marc A; Klok, Harm-Anton

2008-06-21

This feature article provides a compilation of tools available for preparing well-defined peptide/protein-polymer conjugates, which are defined as hybrid constructs combining (i) a defined number of peptide/protein segments with uniform chain lengths and defined monomer sequences (primary structure) with (ii) a defined number of synthetic polymer chains. The first section describes methods for post-translational, or direct, introduction of chemoselective handles onto natural or synthetic peptides/proteins. Addressed topics include the residue- and/or site-specific modification of peptides/proteins at Arg, Asp, Cys, Gln, Glu, Gly, His, Lys, Met, Phe, Ser, Thr, Trp, Tyr and Val residues and methods for producing peptides/proteins containing non-canonical amino acids by peptide synthesis and protein engineering. In the second section, methods for introducing chemoselective groups onto the side-chain or chain-end of synthetic polymers produced by radical, anionic, cationic, metathesis and ring-opening polymerization are described. The final section discusses convergent and divergent strategies for covalently assembling polymers and peptides/proteins. An overview of the use of chemoselective reactions such as Heck, Sonogashira and Suzuki coupling, Diels-Alder cycloaddition, Click chemistry, Staudinger ligation, Michael's addition, reductive alkylation and oxime/hydrazone chemistry for the convergent synthesis of peptide/protein-polymer conjugates is given. Divergent approaches for preparing peptide/protein-polymer conjugates which are discussed include peptide synthesis from synthetic polymer supports, polymerization from peptide/protein macroinitiators or chain transfer agents and the polymerization of peptide side-chain monomers.

Hybrid tandem solar cells with depleted-heterojunction quantum dot and polymer bulk heterojunction subcells

KAUST Repository

Kim, Taesoo

2015-10-01

We investigate hybrid tandem solar cells that rely on the combination of solution-processed depleted-heterojunction colloidal quantum dot (CQD) and bulk heterojunction polymer:fullerene subcells. The hybrid tandem solar cell is monolithically integrated and electrically connected in series with a suitable p-n recombination layer that includes metal oxides and a conjugated polyelectrolyte. We discuss the monolithic integration of the subcells, taking into account solvent interactions with underlayers and associated constraints on the tandem architecture, and show that an adequate device configuration consists of a low bandgap CQD bottom cell and a high bandgap polymer:fullerene top cell. Once we optimize the recombination layer and individual subcells, the hybrid tandem device reaches a VOC of 1.3V, approaching the sum of the individual subcell voltages. An impressive fill factor of 70% is achieved, further confirming that the subcells are efficiently connected via an appropriate recombination layer. © 2015.

Conjugated polymers developed from alkynes

Institute of Scientific and Technical Information of China (English)

Yajing Liu; Jacky W.Y.Lam; Ben Zhong Tang

2015-01-01

The numerous merits of conjugated polymers(CPs) have encouraged scientists to develop a variety of synthetic routes to CPs with diverse structures and functionalities. Among the large scope of substrates,alkyne plays an important role in constructing polymers with conjugated backbones. In addition to some well-developed reactions including Glaser–Hay and Sonogashira coupling, azide/thiol-yne click reaction and cyclotrimerization, some novel alkyne-based reactions have also been explored such as oxidative polycoupling, decarbonylative polycoupling and multicomponent tandem polymerizations. his review focuses on the recent progress on the synthetic methodology of CPs in the last ive years using monomers with two or more triple bonds and some of their high-technological applications. Selected examples of materials properties of these CPs are given in this review, such as luorescence response to chemical or physical stimuli, magnetism, white light emission, cell imaging and bioprobing. Finally, a short perspective is raised in regard to the outlook of the preparation methodologies, functionalities as well as potential applications of CPs in the future.

Photovoltaic cells made from conjugated polymers infiltrated into ordered nanoporous hosts

Science.gov (United States)

Coakley, Kevin M.

Semiconducting (conjugated) polymers have several properties which make them ideal candidates for use in low-cost photovoltaic (PV) cells, including their typically high (105 cm-1) optical absorption coefficients, their ability to be cast from solution using a variety of wet-processing techniques, and the ability to tune their band gap. While most approaches for making conjugated polymer-based PV cells involve randomly intermixing the polymers with electron acceptors that act as sites for exciton dissociation, we have sought to obtain a more optimized morphology of the blended materials through a self-assembly technique. In the first half of this dissertation, we describe our preliminary attempts to make PV cells from conjugated polymers infiltrated into a self-assembled mesoporous titanic (TiO 2) electron acceptor that is ordered on the nanometer length scale. We first present a procedure for fabricating films of mesoporous TiO 2 and then show how its pores can be filled with a conjugated polymer, regioregular poly(3-hexylthiophene) (P3HT). In these films we have achieved precise control of the morphology of the two materials that has not yet been achieved elsewhere. However, as discussed subsequently, the photovoltaic performance of these films has not yet reached the level achieved by other types of conjugated polymer-based PV cells, with a maximum achieved power efficiency of approximately 0.45%. In the second half of this dissertation, we embark on a more fundamental study of the materials requirements for efficient polymer photovoltaics, including models that show how the maximum achievable power efficiency is limited by energy loss during forward electron transfer, and how the maximum achievable photocurrent is limited by the limiting carrier mobility and back electron transfer. Our modeling suggests that, for a back recombination time constant of 1 mus, a limiting carrier mobility of 10-3--10 -2 cm2/Vs is required in order to achieve a large photocurrent

Heparin conjugated quantum dots for in vitro imaging applications.

Science.gov (United States)

Maguire, Ciaran Manus; Mahfoud, Omar Kazem; Rakovich, Tatsiana; Gerard, Valerie Anne; Prina-Mello, Adriele; Gun'ko, Yurii; Volkov, Yuri

2014-11-01

In this work heparin-gelatine multi-layered cadmium telluride quantum dots (QDgel/hep) were synthesised using a novel 'one-pot' method. The QDs produced were characterised using various spectroscopic and physiochemical techniques. Suitable QDs were then selected and compared to thioglycolic acid stabilised quantum dots (QDTGA) and gelatine coated quantum dots (QDgel) for utilisation in in vitro imaging experiments on live and fixed permeabilised THP-1, A549 and Caco-2 cell lines. Exposure of live THP-1 cells to QDgel/hep resulted in localisation of the QDs to the nucleus of the cells. QDgel/hep show affinity for the nuclear compartment of fixed permeabilised THP-1 and A549 cells but remain confined to cytoplasm of fixed permeabilised Caco-2 cells. It is postulated that heparin binding to the CD11b receptor facilitates the internalisation of the QDs into the nucleus of THP-1 cells. In addition, the heparin layer may reduce the unfavourable thrombogenic nature of quantum dots observed in vivo. In this study, heparin conjugated quantum dots were found to have superior imaging properties compared to its native counterparts. The authors postulate that heparin binding to the CD11b receptor facilitates QD internalization to the nucleus, and the heparin layer may reduce the in vivo thrombogenic properties of quantum dots. Copyright © 2014 Elsevier Inc. All rights reserved.

Effects of the Substituents of Boron Atoms on Conjugated Polymers Containing B←N Units.

Science.gov (United States)

Liu, Jun; Wang, Tao; Dou, Chuandong; Wang, Lixiang

2018-06-15

Organoboron chemistry is a new tool to tune the electronic structures and properties of conjugated polymers, which are important for applications in organic opto-electronic devices. To investigate the effects of substituents of boron atoms on conjugated polymers, we synthesized three conjugated polymers based on double B←N bridged bipyridine (BNBP) with various substituents on the boron atoms. By changing the substituents from four phenyl groups and two phenyl groups/two fluorine atoms to four fluorine atoms, the BNBP-based polymers show the blue-shifted absorption spectra, decreased LUMO/HOMO energy levels and enhanced electron affinities, as well as the increased electron mobilities. Moreover, these BNBP-based polymers can be used as electron acceptors for all-polymer solar cells. These results demonstrate that the substituents of boron atoms can effectively modulate the electronic properties and applications of conjugated polymers. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conjugated Polymer Actuators: Prospects and Limitations

DEFF Research Database (Denmark)

Skaarup, Steen

2007-01-01

Actuators constructed with a conjugated polymer as the active part have been predicted to have a number of highly desirable properties: Large mechanical strength, high power density, i.e. high actuation speeds possible, sufficient maximum strain values, high reversibility and safe, low voltages (1...

Analytical characterization of polymer-drug conjugates

International Nuclear Information System (INIS)

Rizzo, V.; Gigli, M.; Pinciroli, V.

1998-01-01

A few polymeric conjugates of antitumor drugs have been recently developed in view of possible therapeutic advantages: solubilization of sparingly soluble drugs in water, improvement of therapeutic index, organ targeting through a second chemical species bound to the same polymeric chain. In this article it's described the analytical approach used in the characterization of the conjugates for chemical identity, purity and strength of the contained active ingredient. The techniques are: high field NMR and size exclusion chromatography with non-aqueous mobile phase for identity; selective hydrolysis and HPLC for strength and purity. A complete and reliable picture is thus obtained both for qualitative and for quantitative aspects. This is an important step forward in the direction of further development and marketing of polymer-drug conjugates [it

Conjugated Polymers Atypically Prepared in Water

Science.gov (United States)

Invernale, Michael A.; Pendergraph, Samuel A.; Yavuz, Mustafa S.; Ombaba, Matthew; Sotzing, Gregory A.

2010-01-01

Processability remains a fundamental issue for the implementation of conducting polymer technology. A simple synthetic route towards processable precursors to conducting polymers (main chain and side chain) was developed using commercially available materials. These soluble precursor systems were converted to conjugated polymers electrochemically in aqueous media, offering a cheaper and greener method of processing. Oxidative conversion in aqueous and organic media each produced equivalent electrochromics. The precursor method enhances the yield of the electrochromic polymer obtained over that of electrodeposition, and it relies on a less corruptible electrolyte bath. However, electrochemical conversion of the precursor polymers often relies on organic salts and solvents. The ability to achieve oxidative conversion in brine offers a less costly and a more environmentally friendly processing step. It is also beneficial for biological applications. The electrochromics obtained herein were evaluated for electronic, spectral, and morphological properties. PMID:20959869

Conjugated polymer energy level shifts in lithium-ion battery electrolytes.

Science.gov (United States)

Song, Charles Kiseok; Eckstein, Brian J; Tam, Teck Lip Dexter; Trahey, Lynn; Marks, Tobin J

2014-11-12

The ionization potentials (IPs) and electron affinities (EAs) of widely used conjugated polymers are evaluated by cyclic voltammetry (CV) in conventional electrochemical and lithium-ion battery media, and also by ultraviolet photoelectron spectroscopy (UPS) in vacuo. By comparing the data obtained in the different systems, it is found that the IPs of the conjugated polymer films determined by conventional CV (IPC) can be correlated with UPS-measured HOMO energy levels (EH,UPS) by the relationship EH,UPS = (1.14 ± 0.23) × qIPC + (4.62 ± 0.10) eV, where q is the electron charge. It is also found that the EAs of the conjugated polymer films measured via CV in conventional (EAC) and Li(+) battery (EAB) media can be linearly correlated by the relationship EAB = (1.07 ± 0.13) × EAC + (2.84 ± 0.22) V. The slopes and intercepts of these equations can be correlated with the dielectric constants of the polymer film environments and the redox potentials of the reference electrodes, as modified by the surrounding electrolyte, respectively.

Quantum dot nanoparticle conjugation, characterization, and applications in neuroscience

Science.gov (United States)

Pathak, Smita

Quantum dot are semiconducting nanoparticles that have been used for decades in a variety of applications such as solar cells, LEDs and medical imaging. Their use in the last area, however, has been extremely limited despite their potential as revolutionary new biological labeling tools. Quantum dots are much brighter and more stable than conventional fluorophores, making them optimal for high resolution imaging and long term studies. Prior work in this area involves synthesizing and chemically conjugating quantum dots to molecules of interest in-house. However this method is both time consuming and prone to human error. Additionally, non-specific binding and nanoparticle aggregation currently prevent researchers from utilizing this system to its fullest capacity. Another critical issue that has not been addressed is determining the number of ligands bound to nanoparticles, which is crucial for proper interpretation of results. In this work, methods to label fixed cells using two types of chemically modified quantum dots are studied. Reproducible non-specific artifact labeling is consistently demonstrated if antibody-quantum dot conditions are less than optimal. In order to explain this, antibodies bound to quantum dots were characterized and quantified. While other groups have qualitatively characterized antibody functionalized quantum dots using TEM, AFM, UV spectroscopy and gel electrophoresis, and in some cases have reported calculated estimates of the putative number of total antibodies bound to quantum dots, no quantitative experimental results had been reported prior to this work. The chemical functionalization and characterization of quantum dot nanocrystals achieved in this work elucidates binding mechanisms of ligands to nanoparticles and allows researchers to not only translate our tools to studies in their own areas of interest but also derive quantitative results from these studies. This research brings ease of use and increased reliability to

Controlling photophysical properties of ultrasmall conjugated polymer nanoparticles through polymer chain packing

KAUST Repository

Piwonski, Hubert Marek

2017-05-16

Applications of conjugated polymer nanoparticles (Pdots) for imaging and sensing depend on their size, fluorescence brightness and intraparticle energy transfer. The molecular design of conjugated polymers (CPs) has been the main focus of the development of Pdots. Here we demonstrate that proper control of the physical interactions between the chains is as critical as the molecular design. The unique design of twisted CPs and fine-tuning of the reprecipitation conditions allow us to fabricate ultrasmall (3.0–4.5 nm) Pdots with excellent photostability. Extensive photophysical and structural characterization reveals the essential role played by the packing of the polymer chains in the particles in the intraparticle spatial alignment of the emitting sites, which regulate the fluorescence brightness and the intraparticle energy migration efficiency. Our findings enhance understanding of the relationship between chain interactions and the photophysical properties of CP nanomaterials, providing a framework for designing and fabricating functional Pdots for imaging applications.

Lead selenide quantum dot polymer nanocomposites

Science.gov (United States)

Waldron, Dennis L.; Preske, Amanda; Zawodny, Joseph M.; Krauss, Todd D.; Gupta, Mool C.

2015-02-01

Optical absorption and fluorescence properties of PbSe quantum dots (QDs) in an Angstrom Bond AB9093 epoxy polymer matrix to form a nanocomposite were investigated. To the authors’ knowledge, this is the first reported use of AB9093 as a QD matrix material and it was shown to out-perform the more common poly(methyl methacrylate) matrix in terms of preserving the optical properties of the QD, resulting in the first reported quantum yield (QY) for PbSe QDs in a polymer matrix, 26%. The 1-s first excitonic absorption peak of the QDs in a polymer matrix red shifted 65 nm in wavelength compared to QDs in a hexane solution, while the emission peak in the polymer matrix red shifted by 38 nm. The fluorescence QY dropped from 55% in hexane to 26% in the polymer matrix. A time resolved fluorescence study of the QDs showed single exponential lifetimes of 2.34 and 1.34 μs in toluene solution and the polymer matrix respectively.

Femtosecond Pump-Push-Probe and Pump-Dump-Probe Spectroscopy of Conjugated Polymers: New Insight and Opportunities.

Science.gov (United States)

Kee, Tak W

2014-09-18

Conjugated polymers are an important class of soft materials that exhibit a wide range of applications. The excited states of conjugated polymers, often referred to as excitons, can either deactivate to yield the ground state or dissociate in the presence of an electron acceptor to form charge carriers. These interesting properties give rise to their luminescence and the photovoltaic effect. Femtosecond spectroscopy is a crucial tool for studying conjugated polymers. Recently, more elaborate experimental configurations utilizing three optical pulses, namely, pump-push-probe and pump-dump-probe, have been employed to investigate the properties of excitons and charge-transfer states of conjugated polymers. These studies have revealed new insight into femtosecond torsional relaxation and detrapping of bound charge pairs of conjugated polymers. This Perspective highlights (1) the recent achievements by several research groups in using pump-push-probe and pump-dump-probe spectroscopy to study conjugated polymers and (2) future opportunities and potential challenges of these techniques.

Incorporating functionalized polyethylene glycol lipids into reprecipitated conjugated polymer nanoparticles for bioconjugation and targeted labeling of cells

Science.gov (United States)

Kandel, Prakash K.; Fernando, Lawrence P.; Ackroyd, P. Christine; Christensen, Kenneth A.

2011-03-01

We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG) lipids by reprecipitation. These nanoparticles retain the fundamental spectroscopic properties of conjugated polymer nanoparticles prepared without PEG lipid, but demonstrate greater hydrophilicity and quantum yield compared to unmodified conjugated polymer nanoparticles. The sizes of these nanoparticles, as determined by TEM, were 21-26 nm. Notably, these nanoparticles were prepared with several PEG lipid functional end groups, including biotin and carboxy moieties that can be easily conjugated to biomolecules. We have demonstrated the availability of these end groups for functionalization using the interaction of biotin PEG lipid conjugated polymer nanoparticles with streptavidin. Biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-linked magnetic beads, while carboxy and methoxy PEG lipid modified nanoparticles did not. Similarly, biotinylated PEG lipid conjugated polymer nanoparticles bound streptavidin-coated glass slides and could be visualized as diffraction-limited spots, while nanoparticles without PEG lipid or with non-biotin PEG lipid end groups were not bound. To demonstrate that nanoparticle functionalization could be used for targeted labelling of specific cellular proteins, biotinylated PEG lipid conjugated polymer nanoparticles were bound to biotinylated anti-CD16/32 antibodies on J774A.1 cell surface receptors, using streptavidin as a linker. This work represents the first demonstration of targeted delivery of conjugated polymer nanoparticles and demonstrates the utility of these new nanoparticles for fluorescence based imaging and sensing.We report a simple and rapid method to prepare extremely bright, functionalized, stable, and biocompatible conjugated polymer nanoparticles incorporating functionalized polyethylene glycol (PEG

Compositions for directed alignment of conjugated polymers

Science.gov (United States)

Kim, Jinsang; Kim, Bong-Gi; Jeong, Eun Jeong

2016-04-19

Conjugated polymers (CPs) achieve directed alignment along an applied flow field and a dichroic ratio of as high as 16.67 in emission from well-aligned thin films and fully realized anisotropic optoelectronic properties of CPs in field-effect transistor (FET).

Photoinduced partial charge transfer between conjugated polymer and fullerene in solutions

International Nuclear Information System (INIS)

Lin Hongzhen; Weng Yufeng; Huang Hongmin; He Qingguo; Zheng Min; Bai Fenglian

2004-01-01

Photoinduced charge transfer between a conjugated polymer and C 60 and the related processes were investigated in dilute solutions. The substantial fluorescence quenching is correlated with the efficient exciton diffusion within the polymer chains, according to which a sphere-of-action mechanism is proposed. An emissive exciplex was found formed between the conjugated polymer and fullerene in a nonpolar solvent, indicating the occurrence of a photoinduced partial charge transfer process. The low-energy sites in the polymer are believed to play a crucial role in the partial charge transfer. The asymmetry of the exciplex provides a method for evaluating the tendency of photoinduced charge separation between the donor and the acceptor. This method allows screening candidates for photovoltaic applications

Simple Protein Modification Using Zwitterionic Polymer to Mitigate the Bioactivity Loss of Conjugated Insulin.

Science.gov (United States)

Xie, Jinbing; Lu, Yang; Wang, Wei; Zhu, Hui; Wang, Zhigang; Cao, Zhiqiang

2017-06-01

Polymer-protein conjugation has been extensively explored toward a better protein drug with improved pharmacokinetics. However, a major problem with polymer-protein conjugation is that the polymers drastically reduce the bioactivity of the modified protein. There is no perfect solution to prevent the bioactivity loss, no matter the polymer is conjugated in a non-site specific way, or a more complex site-specific procedure. Here the authors report for the first time that when zwitterionic carboxybetaine polymer (PCB) is conjugated to insulin through simple conventional coupling chemistry. The resulting PCB-insulin does not show a significant reduction of in vitro bioactivity. The obtained PCB-insulin shows two significant advantages as a novel pharmaceutical agent. First, its therapeutic performance is remarkable. For PCB-insulin, there is a 24% increase of in vivo pharmacological activity of lowering blood glucose compared with native insulin. Such uncommonly seen increase has rarely been reported and is expected to be due to both the improved pharmacokinetics and retained bioactivity of PCB-insulin. Second, the production is simple from manufacturing standpoints. Conjugation procedure involves only one-step coupling reaction without complex site-specific linkage technique. The synthesized PCB-insulin conjugates do not require chromatographic separation to purify and obtain particular isoforms. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Particle-in-a-box model of exciton absorption and electroabsorption in conjugated polymers

Science.gov (United States)

Pedersen, Thomas G.

2000-12-01

The recently proposed particle-in-a-box model of one-dimensional excitons in conjugated polymers is applied in calculations of optical absorption and electroabsorption spectra. It is demonstrated that for polymers of long conjugation length a superposition of single exciton resonances produces a line shape characterized by a square-root singularity in agreement with experimental spectra near the absorption edge. The effects of finite conjugation length on both absorption and electroabsorption spectra are analyzed.

Exploring the origin of high optical absorption in conjugated polymers

KAUST Repository

Vezie, Michelle S.; Few, Sheridan; Meager, Iain; Pieridou, Galatia; Dö rling, Bernhard; Ashraf, Raja Shahid; Goñ i, Alejandro R.; Bronstein, Hugo; McCulloch, Iain; Hayes, Sophia C.; Campoy-Quiles, Mariano; Nelson, Jenny

2016-01-01

The specific optical absorption of an organic semiconductor is critical to the performance of organic optoelectronic devices. For example, higher light-harvesting efficiency can lead to higher photocurrent in solar cells that are limited by sub-optimal electrical transport. Here, we compare over 40 conjugated polymers, and find that many different chemical structures share an apparent maximum in their extinction coefficients. However, a diketopyrrolopyrrole-thienothiophene copolymer shows remarkably high optical absorption at relatively low photon energies. By investigating its backbone structure and conformation with measurements and quantum chemical calculations, we find that the high optical absorption can be explained by the high persistence length of the polymer. Accordingly, we demonstrate high absorption in other polymers with high theoretical persistence length. Visible light harvesting may be enhanced in other conjugated polymers through judicious design of the structure.

Exploring the origin of high optical absorption in conjugated polymers

KAUST Repository

Vezie, Michelle S.

2016-05-16

The specific optical absorption of an organic semiconductor is critical to the performance of organic optoelectronic devices. For example, higher light-harvesting efficiency can lead to higher photocurrent in solar cells that are limited by sub-optimal electrical transport. Here, we compare over 40 conjugated polymers, and find that many different chemical structures share an apparent maximum in their extinction coefficients. However, a diketopyrrolopyrrole-thienothiophene copolymer shows remarkably high optical absorption at relatively low photon energies. By investigating its backbone structure and conformation with measurements and quantum chemical calculations, we find that the high optical absorption can be explained by the high persistence length of the polymer. Accordingly, we demonstrate high absorption in other polymers with high theoretical persistence length. Visible light harvesting may be enhanced in other conjugated polymers through judicious design of the structure.

Stabilization of Resveratrol in Blood Circulation by Conjugation to mPEG and mPEG-PLA Polymers: Investigation of Conjugate Linker and Polymer Composition on Stability, Metabolism, Antioxidant Activity and Pharmacokinetic Profile

Science.gov (United States)

Siddalingappa, Basavaraj; Benson, Heather A. E.; Brown, David H.; Batty, Kevin T.; Chen, Yan

2015-01-01

Resveratrol is naturally occurring phytochemical with diverse biological activities such as chemoprevention, anti-inflammatory, anti-cancer, anti-oxidant. But undergoes rapid metabolism in the body (half life 0.13h). Hence Polymer conjugation utilizing different chemical linkers and polymer compositions was investigated for enhanced pharmacokinetic profile of resveratrol. Ester conjugates such as α-methoxy-ω-carboxylic acid poly(ethylene glycol) succinylamide resveratrol (MeO-PEGN-Succ-RSV) (2 and 20 kDa); MeO-PEG succinyl ester resveratrol (MeO-PEGO-Succ-RSV) (2 kDa); α-methoxy poly(ethylene glycol)-co-polylactide succinyl ester resveratrol (MeO-PEG-PLAO-Succ-RSV) (2 and 6.6kDa) were prepared by carbodiimide coupling reactions. Resveratrol-PEG ethers (2 and 5 kDa) were synthesized by alkali-mediated etherification. All polymer conjugates were fully characterized in vitro and the pharmacokinetic profile of selected conjugates was characterized in rats. Buffer and plasma stability of conjugates was dependent on polymer hydrophobicity, aggregation behavior and PEG corona, with MeO-PEG-PLAO-Succ-RSV (2 kDa) showing a 3h half-life in rat plasma in vitro. Polymer conjugates irrespective of linker chemistry protected resveratrol against metabolism in vitro. MeO-PEG-PLAO-Succ-RSV (2 kDa), Resveratrol-PEG ether (2 and 5 kDa) displayed improved pharmacokinetic profiles with significantly higher plasma area under curve (AUC), slower clearance and smaller volume of distribution, compared to resveratrol. PMID:25799413

Impact of Backbone Fluorination on π-Conjugated Polymers in Organic Photovoltaic Devices: A Review

Directory of Open Access Journals (Sweden)

Nicolas Leclerc

2016-01-01

Full Text Available Solution-processed bulk heterojunction solar cells have experienced a remarkable acceleration in performances in the last two decades, reaching power conversion efficiencies above 10%. This impressive progress is the outcome of a simultaneous development of more advanced device architectures and of optimized semiconducting polymers. Several chemical approaches have been developed to fine-tune the optoelectronics and structural polymer parameters required to reach high efficiencies. Fluorination of the conjugated polymer backbone has appeared recently to be an especially promising approach for the development of efficient semiconducting polymers. As a matter of fact, most currently best-performing semiconducting polymers are using fluorine atoms in their conjugated backbone. In this review, we attempt to give an up-to-date overview of the latest results achieved on fluorinated polymers for solar cells and to highlight general polymer properties’ evolution trends related to the fluorination of their conjugated backbone.

Methyllithium-Doped Naphthyl-Containing Conjugated Microporous Polymer with Enhanced Hydrogen Storage Performance.

Science.gov (United States)

Xu, Dan; Sun, Lei; Li, Gang; Shang, Jin; Yang, Rui-Xia; Deng, Wei-Qiao

2016-06-01

Hydrogen storage is a primary challenge for using hydrogen as a fuel. With ideal hydrogen storage kinetics, the weak binding strength of hydrogen to sorbents is the key barrier to obtain decent hydrogen storage performance. Here, we reported the rational synthesis of a methyllithium-doped naphthyl-containing conjugated microporous polymer with exceptional binding strength of hydrogen to the polymer guided by theoretical simulations. Meanwhile, the experimental results showed that isosteric heat can reach up to 8.4 kJ mol(-1) and the methyllithium-doped naphthyl-containing conjugated microporous polymer exhibited an enhanced hydrogen storage performance with 150 % enhancement compared with its counterpart naphthyl-containing conjugated microporous polymer. These results indicate that this strategy provides a direction for design and synthesis of new materials that meet the US Department of Energy (DOE) hydrogen storage target. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Scanning-tunneling spectroscopy on conjugated polymer films

NARCIS (Netherlands)

Kemerink, M.; Alvarado, S.F.; Koenraad, P.M.; Janssen, R.A.J.; Salemink, H.W.M.; Wolter, J.H.; Blom, P.W.M.

2003-01-01

Scanning-tunneling spectroscopy experiments have been performed on conjugated polymer films and have been compared to a three-dimensional numerical model for charge injection and transport. It is found that field enhancement near the tip apex leads to significant changes in the injected current,

Synthesis of novel monomeric graphene quantum dots and corresponding nanocomposite with molecularly imprinted polymer for electrochemical detection of an anticancerous ifosfamide drug.

Science.gov (United States)

Bali Prasad, Bhim; Kumar, Anil; Singh, Ragini

2017-08-15

This paper reports a typical synthesis of a nanocomposite of functionalized graphene quantum dots and imprinted polymer at the surface of screen-printed carbon electrode using N-acryloyl-4-aminobenzamide, as a functional monomer, and an anticancerous drug, ifosfamide, as a print molecule (test analyte). Herein, graphene quantum dots in nanocomposite practically induced the electrocatalytic activity by lowering the oxidation overpotential of test analyte and thereby amplifying electronic transmission, without any interfacial barrier in between the film and the electrode surface. The differential pulse anodic stripping signal at functionalized graphene quantum dots based imprinted sensor was realized to be about 3- and 7-fold higher as compared to the traditionally made imprinted polymers prepared in the presence and the absence of graphene quantum dots (un-functionalized), respectively. This may be attributed to a pertinent synergism in between the positively charged functionalized graphene quantum dots in the film and the target analyte toward the enhancement of electro-conductivity of the film and thereby the electrode kinetics. In fact, the covalent attachment of graphene quantum dots with N-acryloyl-4-aminobenzamide molecules might exert an extended conjugation at their interface facilitating electro conducting to render the channelized pathways for the electron transport. The proposed sensor is practically applicable to the ultratrace evaluation of ifosfamide in real (biological/pharmaceutical) samples with detection limit as low as 0.11ngmL -1 (S/N=3), without any matrix effect, cross-reactivity, and false-positives. Copyright © 2017 Elsevier B.V. All rights reserved.

Photochemical stability of π-conjugated polymers for polymer solar cells: a rule of thumb

DEFF Research Database (Denmark)

Manceau, Matthieu; Bundgaard, Eva; Carlé, Jon Eggert

2011-01-01

A comparative photochemical stability study of a wide range of π-conjugated polymers relevant to polymer solar cells is presented. The behavior of each material has been investigated under simulated sunlight (1 sun, 1000 W m−2, AM 1.5G) and ambient atmosphere. Degradation was monitored during age...... ageing combining UV-visible and infrared spectroscopies. From the comparison of the collected data, the influence of the polymer chemical structure on its stability has been discussed. General rules relative to the polymer structure–stability relationship are proposed....

α-Methylprednisolone conjugated cyclodextrin polymer-based nanoparticles for rheumatoid arthritis therapy

Directory of Open Access Journals (Sweden)

Jungyeon Hwang

2008-10-01

Full Text Available Jungyeon Hwang1, Kathleen Rodgers2, James C Oliver3, Thomas Schluep11Insert Therapeutics, Inc., Pasadena, CA, USA; 2Livingston Research Institute, Los Angeles, CA, USA; James C Oliver, Peptagen, Inc., Raleigh, NC USAAbstract: A glycinate derivative of α-methylprednisolone (MP was prepared and conjugated to a linear cyclodextrin polymer (CDP with a loading of 12.4% w/w. The polymer conjugate (CDP-MP self-assembled into nanoparticles with a size of 27 nm. Release kinetics of MP from the polymer conjugate showed a half-life (t1/2 of 50 h in phosphate buffer solution (PBS and 19 h in human plasma. In vitro, the proliferation of human lymphocytes was suppressed to a similar extent but with a delayed effect when CDP-MP was compared with free MP. In vivo, CDP-MP was administered intravenously to mice with collagen-induced arthritis and compared with free MP. CDP-MP was administered weekly for six weeks (0.07, 0.7, and 7 mg/kg/week and MP was administered daily for six weeks (0.01, 0.1, and 1 mg/kg/day. Body weight changes were minimal in all animals. After 28 days, a significant decrease in arthritis score was observed in animals treated weekly with an intermediate or high dose of CDP-MP. Additionally, dorsoplantar swelling was reduced to baseline in animals treated with CDP-MP at the intermediate and high dose level. Histological evaluation showed a reduction in synovitis, pannus formation and disruption of architecture at the highest dose level of CDP-MP. MP administered daily at equivalent cumulative doses showed minimal efficacy in this model. This study demonstrates that conjugation of MP to a cyclodextrin-polymer may improve its efficacy, leading to lower doses and less frequent administration for a safer and more convenient management of rheumatoid arthritis.Keywords: α-methylprednisolone (MP, cyclodextrin polymer (CDP, polymer conjugate (CDP-MP, rheumatoid arthritis (RA, enhanced permeability and retention effect (EPR

Polymer-assisted synthesis of water-soluble PbSe quantum dots

International Nuclear Information System (INIS)

Melnig, V.; Apostu, M.-O.; Foca, N.

2008-01-01

Stable PbSe quantum dots were synthesised in water-based media using poly(amidehydroxyurethane) water-soluble polymer. The polymer acts like a precursor carrier, blocks the particles aggregation and assures their solubility. Atomic force microscopy data show that the particle radius is smaller than the Bohr radius of PbSe. Interactions studies, performed by Fourier transform IR spectroscopy, show that the quantum dots are capped with poly(amidehydroxyurethane). The proposed synthesis was realised in the absence of any organic solvent. As a result, the produced particles have good water solubility, stability and good arguments to be biologically compatible.

Anti-VEGF antibody conjugated CdHgTe quantum dots as a fluorescent probe for imaging in living mouse

Energy Technology Data Exchange (ETDEWEB)

Pang, Lili; Cui, Hongjing [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing (China); Liu, Yu [Department of Biochemistry, School of Life Science and Technology, China Pharmaceutical University, Nanjing (China); Zhong, Wenying, E-mail: wyzhong@cpu.edu.cn [Department of Analytical Chemistry, China Pharmaceutical University, Nanjing (China); Key laboratory of Biomedical Functional Materials, China Pharmaceutical University, Nanjing (China)

2016-05-15

The dual-function anti-VEGF antibody conjugated CdHgTe quantum dots with good targeting property was successfully prepared. In this system, anti-VEGF antibody is not only a target agent but also a therapeutic drug. The anti-VEGF antibody conjugated near-infrared quantum dots can achieve the purposes of detection and treatment at the same time. As-prepared dual-function fluorescent probe in this work has been successfully applied for in vivo and in vitro imaging, which is promising in rapid tumor detection.

Impact of morphology on polaron delocalization in a semicrystalline conjugated polymer

KAUST Repository

Steyrleuthner, Robert

2016-12-20

We investigate the delocalization of holes in the semicrystalline conjugated polymer poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT) by directly measuring the hyperfine coupling between photogenerated polarons and bound nuclear spins using electron nuclear double resonance spectroscopy. An extrapolation of the corresponding oligomer spectra reveals that charges tend to delocalize over 4.0-4.8 nm with delocalization strongly dependent on molecular order and crystallinity of the PBTTT polymer thin films. Density functional theory calculations of hyperfine couplings confirm that long-range corrected functionals appropriately describe the change in coupling strength with increasing oligomer size and agree well with the experimentally measured polymer limit. Our discussion presents general guidelines illustrating the various pitfalls and opportunities when deducing polaron localization lengths from hyperfine coupling spectra of conjugated polymers.

Thiolated polymers--thiomers: development and in vitro evaluation of chitosan-thioglycolic acid conjugates.

Science.gov (United States)

Kast, C E; Bernkop-Schnürch, A

2001-09-01

The aim of this study was to improve mucoadhesive properties of chitosan by the covalent attachment of thiol moieties to this cationic polymer. Mediated by a carbodiimide, thioglycolic acid (TGA) was covalently attached to chitosan. This was achieved by the formation of amide bonds between the primary amino groups of the polymer and the carboxylic acid group of TGA. Dependent on the pH-value and the weight ratio of polymer to TGA during the coupling reaction the resulting thiolated polymers, the so-called thiomers, displayed 6.58, 9.88, 27.44, and 38.23 micromole thiol groups per gram polymer. Tensile studies carried out with these chitosan-TGA conjugates on freshly excised porcine intestinal mucosa demonstrated a 6.3-, 8.6-, 8.9-, and 10.3-fold increase in the total work of adhesion (TWA) compared to the unmodified polymer, respectively. In contrast, the combination of chitosan and free unconjugated TGA showed almost no mucoadhesion. These data were in good correlation with further results obtained by another mucoadhesion test demonstrating a prolonged residence time of thiolated chitosan on porcine mucosa. The swelling behavior of all conjugates was thereby exactly in the same range as for an unmodified polymer pretreated in the same way. Furthermore, it could be shown that chitosan-TGA conjugates are still biodegradable by the glycosidase lysozyme. According to these results. chitosan-TGA conjugates represent a promising tool for the development of mucoadhesive drug delivery systems.

Effect of backbone structure on charge transport along isolated conjugated polymer chains

International Nuclear Information System (INIS)

Siebbeles, Laurens D.A.; Grozema, Ferdinand C.; Haas, Matthijs P. de; Warman, John M.

2005-01-01

Fast charge transport in conjugated polymers is essential for their application in opto-electronic devices. In the present paper, measurements and theoretical modeling of the mobility of excess charges along isolated chains of conjugated polymers in dilute solution are presented. Charge carriers were produced by irradiation of the polymer solution with 3-MeV electrons from a Van de Graaff accelerator. The mobilities of the charges along the polymer chains were obtained from time-resolved microwave conductivity measurements. The mobilities are strongly dependent on the chemical nature of the polymer backbone. Comparison of the experimental data with results from ab initio quantum mechanical calculations shows that the measured mobilities are strongly limited by torsional disorder, chemical defects and chain ends. Improvement of the structure of polymer backbones is therefore expected to significantly enhance the performance of these materials in 'plastic electronics'

Combination of carbon dot and polymer dot phosphors for white light-emitting diodes.

Science.gov (United States)

Sun, Chun; Zhang, Yu; Sun, Kai; Reckmeier, Claas; Zhang, Tieqiang; Zhang, XiaoYu; Zhao, Jun; Wu, Changfeng; Yu, William W; Rogach, Andrey L

2015-07-28

We realized white light-emitting diodes with high color rendering index (85-96) and widely variable color temperatures (2805-7786 K) by combining three phosphors based on carbon dots and polymer dots, whose solid-state photoluminescence self-quenching was efficiently suppressed within a polyvinyl pyrrolidone matrix. All three phosphors exhibited dominant absorption in the UV spectral region, which ensured the weak reabsorption and no energy transfer crosstalk. The WLEDs showed excellent color stability against the increasing current because of the similar response of the tricolor phosphors to the UV light variation.

Tuneable light-emitting carbon-dot/polymer flexible films prepared through one-pot synthesis

Science.gov (United States)

Bhunia, Susanta Kumar; Nandi, Sukhendu; Shikler, Rafi; Jelinek, Raz

2016-02-01

Development of efficient, inexpensive, and environmentally-friendly light emitters, particularly devices that produce white light, have drawn intense interest due to diverse applications in the lighting industry, photonics, solar energy, and others. We present a simple strategy for the fabrication of flexible transparent films exhibiting tuneable light emission through one-pot synthesis of polymer matrixes with embedded carbon dots assembled in situ. Importantly, different luminescence colours were produced simply by preparing C-dot/polymer films using carbon precursors that yielded C-dots exhibiting distinct fluorescence emission profiles. Furthermore, mixtures of C-dot precursors could be also employed for fabricating films exhibiting different colours. In particular, we successfully produced films emitting white light with attractive properties (i.e. ``warm'' white light with a high colour rendering index) - a highly sought after goal in optical technologies.Development of efficient, inexpensive, and environmentally-friendly light emitters, particularly devices that produce white light, have drawn intense interest due to diverse applications in the lighting industry, photonics, solar energy, and others. We present a simple strategy for the fabrication of flexible transparent films exhibiting tuneable light emission through one-pot synthesis of polymer matrixes with embedded carbon dots assembled in situ. Importantly, different luminescence colours were produced simply by preparing C-dot/polymer films using carbon precursors that yielded C-dots exhibiting distinct fluorescence emission profiles. Furthermore, mixtures of C-dot precursors could be also employed for fabricating films exhibiting different colours. In particular, we successfully produced films emitting white light with attractive properties (i.e. ``warm'' white light with a high colour rendering index) - a highly sought after goal in optical technologies. Electronic supplementary information (ESI

Novel Luminescent Multilayer Films Containing π-Conjugated Anionic Polymer with Electronic Microenvironment

Directory of Open Access Journals (Sweden)

Tianlei Wang

2016-09-01

Full Text Available Layered double hydroxides (LDHs, luminescent π-conjugated anionic polymer and montmorillonite (MMT were orderly assembled into luminescent multilayer films via layer-by-layer self-assembly method. The electronic microenvironment (EME, the structure of which is like a traditional capacitor, can be constructed by exfoliated LDHs or MMT nanosheets. In addition, the rigid inorganic laminated configuration can offer stable surroundings between the interlayers. As a result, we conclude that EME can extend the luminescent lifespans of multilayer films substantially, due to affecting relaxation times of π-conjugated anionic polymer. Consequently, because of the remarkable impact on better photoemission behaviors of luminescent π-conjugated anionic polymer, EME assembled by LDHs or MMT nanosheets have had high hopes attached to them. They are expected to have the potential for designing, constructing, and investigating novel light-emitting thin films.

Modelling the effect of nonplanarity on charge transport along conjugated polymer chains

International Nuclear Information System (INIS)

Correia, Helena M.G.; Ramos, Marta M.D.

2007-01-01

Conjugated polymers show interesting properties that make them appropriated for nanoelectronics. Several studies of poly(p-phenylene vinylene) (PPV) have suggested that each polymer chain consists of several planar segments, with conjugation length of nanoscale dimension, linked by twists or kinks. A pronounced twist between two planar segments in a PPV chain not only causes loss of main-chain conjugation but it may also alter electron and hole mobility along the chain, which has further implications for the percolation of charge through the polymer film. We used self-consistent quantum molecular dynamics calculations to provide information on the electric field needed to move the injected charges (either electrons or holes) along the planar segments of PPV and to cross the twist between two planar segments perpendicular to each other. Field-dependent charge mobility was also estimated for conjugated segments of various lengths. Our results suggest that electrons can cross the twist between adjacent planar segments for lower applied electric fields than holes if there is no more than one electronic charge (electron or hole) on the PPV chain, otherwise similar fields are needed

Singlet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells

KAUST Repository

Dimitrov, Stoichko; Schroeder, Bob; Nielsen, Christian; Bronstein, Hugo; Fei, Zhuping; McCulloch, Iain; Heeney, Martin; Durrant, James

2016-01-01

The lifetime of singlet excitons in conjugated polymer films is a key factor taken into account during organic solar cell device optimization. It determines the singlet exciton diffusion lengths in polymer films and has a direct impact

Realization of large area flexible fullerene - conjugated polymer photocells: a route to plastic solar cells

NARCIS (Netherlands)

Brabec, C.J.; Padinger, F.; Hummelen, J.C.; Janssen, R.A.J.; Sariciftci, N.S.

1999-01-01

Bulk donor — acceptor heterojunctions between conjugated polymers and fullerenes have been utilized for photovoltaic devices with quantum efficiencies of around 1%. These devices are based on the photoinduced, ultrafast electron transfer between non degenerate ground state conjugated polymers and

A possibility for generation of two species of charge carriers along main-chain and side-chains for a π-conjugated polymer

International Nuclear Information System (INIS)

Kudo, Yuki; Kawabata, Kohsuke; Goto, Hiromasa

2013-01-01

Iodide doping produces charge carriers in π-conjugated polymers. Solitons can be generated in the case of polyacetylene, and polarons in the case of aromatic-type conjugated polymers. We synthesized a conjugated main-chain/side-chain polymer, which consists of polyene in the main-chain and aromatic-type conjugated units in the side-chains. Based on the SSH (Su, Schrieffer, Heeger) theoretical model of solitons in one-dimensional conjugated polymers, we experimentally carried out chemical doping to the main-chain/side-chains conjugated polymer. Generation of the charge carriers was examined by electron spin resonance spectroscopy. This study may lead to realization of a dual doping system of solitons and polarons in π-conjugation expanded to two-dimensional directions in polymers.

Conjugation of E. coli O157:H7 Antibody to CdSe/ZnS Quantum Dots

Directory of Open Access Journals (Sweden)

N. T. Vo

2015-01-01

Full Text Available The conjugation of antibody to semiconductor quantum dots plays a very important role in many applications such as bioimaging, biomarking, and biosensing. In this research, we present some results of highly luminescent core/shell structure CdSe/ZnS on which the E. coli antibody was conjugated. The CdSe core was synthesized successfully with chemical “green” method. For biological applications, the capping surfactant, trioctylphosphine oxide, was substituted by a new one, mercaptopropionic acid (MPA, before the antibody attachment step. Finally, the E. coli antibody was attached to quantum dots CdSe/ZnS. Morphology, structure, and optical properties were investigated with PL, UV-Vis, TEM, and XRD methods. The successful ligand substitution and antibody attachment were confirmed by zeta potential measurement, FTIR spectroscopy, and TEM. The results showed quantum dots size of 2.3 nm, uniform distribution, and high luminescence. CdSe/ZnS core/shell structure had better stability and enhanced the luminescence efficiency up to threefold compared with the core CdSe. MPA ligand shifted the initial hydrophobic quantum dots to hydrophilic ones, which helped to dissolve them in organic solvents and attach the antibody.

Synthesis and characterization of a cysteine xyloglucan conjugate as mucoadhesive polymer

Directory of Open Access Journals (Sweden)

Mangesh Bhalekar

2013-06-01

Full Text Available The aim of this study was to improve the mucoadhesive potential of xyloglucan polymer by the covalent attachment of cysteine as thiol moiety. The parent polymer xyloglucan was chemically modified by introducing sulphydryl bearing compound L-cysteine HCl. Different batches of xyloglucan-cysteine conjugates were prepared at varying reaction pH (2-6 and evaluated for optimum thiol incorporation, disulphide group content, swelling behavior, rheological properties and mucoadhesive properties. The obtained conjugates characterized in vitro by quantification of immobilized thiol groups; showed maximum thiol incorporation on xyloglucan (7.67 ± 0.14 % at pH 5. The disulphide group content was found maximum (2.83 ± 0.12 at pH 6. The water uptake at end of 4 h was 5.0 for xyloglucan and was found to decrease in thiolated derivatives with increase in thiolation. Mucoadhesion studies revealed that mucoadhesion of xyloglucan-cysteine conjugate increased more than twice compared to the unmodified polymer. The viscosity of thiomer was more than that of xyloglucan because of formation of disulphide bonds.

Peptides, proteins and peptide/protein-polymer conjugates as drug delivery system.

Science.gov (United States)

Mukherjee, Biswajit; Karmakar, Swapna D; Hossain, Chowdhury M; Bhattacharya, Sanchari

2014-01-01

In the last few decades, novel drug delivery strategies have been a big priority to the formulation scientists. Peptides and proteins have drawn a special attention for their wide scope in the area. Serum albumin, transferrin, recom- binant proteins, virus capsids etc. are used as carrier for drug and biomolecules. Conjugates of polymers with proteins have also shown strong potency in the field of drug delivery. Polyethylene glycol is one of the most successful polymers that has been used extensively to develop protein conjugated formulations. Besides, polyvinyl pyrrolidone, polylactic-co- glycolic acid, N-(2-hydroxypropyl) methacrylamide copolymer, polyglutamic acid have also been investigated. In this re- view, we will highlight on the most recent overview of various advantages, limitations and marketed products of proteins, peptides and protein/peptide-polymer conjugates as drug carriers, such products in clinical trials and their various uses in the field of modern drug delivery. Understanding the key features of these materials and the vigorous research in this field will develop new drug formulations that will combat various types of life-threatening diseases.

Thermo-cleavable solvents for printing conjugated polymers: Application in polymer solar cells

DEFF Research Database (Denmark)

Jørgensen, Mikkel; Hagemann, Ole; Alstrup, Jan

2009-01-01

large-scale production of polymer solar cells using screen printing. Screen-printed solar cells are still very inferior to state of the art P3HT/PCBM technology, but it is our view that it is necessary to explore these printing technologies if polymer solar cells are to ever become commercial products.......The synthesis and characterization of a number of so-called thermo-cleavable solvents are described with their application in all-air, all-solution and all-screen-printed polymer solar cells. These solvents were developed to meet some requirements for printing techniques such as long “open time...... (TGA) and high-temperature NMR established the onset temperature of decomposition, the rate of the reaction and the nature of the products. Printing experiments with inks based on these solvents together with conjugated polymers are exemplified for polymer solar cell devices to show how they enable...

Synthesis and study of conjugated polymers containing Di- or Triphenylamine

Energy Technology Data Exchange (ETDEWEB)

Sukwattanasinitt, M.

1996-06-21

This thesis consists of two separate parts. The first part addresses the synthesis and study of conjugated polymers containing di- or triphenylamine. Two types of polymers: linear polymers and dendrimers, were synthesized. The polymers were characterized by NMR, IR, UV, GPC, TGA and DSC. Electronic and optical properties of the polymers were studied through the conductivity measurements and excitation- emission spectra. the second part of this thesis deals with a reaction of electron-rich acetylenes with TCNE. The discovery of the reaction from charge transfer complex studies and the investigation of this reaction on various electron-rich acetylenes are presented.

Conjugated Polymer with Intrinsic Alkyne Units for Synergistically Enhanced Raman Imaging in Living Cells.

Science.gov (United States)

Li, Shengliang; Chen, Tao; Wang, Yunxia; Liu, Libing; Lv, Fengting; Li, Zhiliang; Huang, Yanyi; Schanze, Kirk S; Wang, Shu

2017-10-16

Development of Raman-active materials with enhanced and distinctive Raman vibrations in the Raman-silent region (1800-2800 cm -1 ) is highly required for specific molecular imaging of living cells with high spatial resolution. Herein, water-soluble cationic conjugated polymers (CCPs), poly(phenylene ethynylene) (PPE) derivatives, are explored for use as alkyne-state-dependent Raman probes for living cell imaging due to synergetic enhancement effect of alkyne vibrations in Raman-silent region compared to alkyne-containing small molecules. The enhanced alkyne signals result from the integration of alkyne groups into the rigid backbone and the delocalized π-conjugated structure. PPE-based conjugated polymer nanoparticles (CPNs) were also prepared as Raman-responsive nanomaterials for distinct imaging application. This work opens a new way into the development of conjugated polymer materials for enhanced Raman imaging. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochromic in conjugated polymers

International Nuclear Information System (INIS)

Picado Valenzuela, Alfredo

2007-01-01

This revision considered object the description of one of the materials with the greatest potential in the field of electrochromic (mainly in the visible region): the conjugated polymers (CP), area of enormous potential both now and in a short time ahead. The CP are insulating materials and organic semiconductors in a state not doped. They can be doped positively or negatively being observed a significant increase in the conductivity and being generated a color change in these materials. The understanding of how optical properties vary based on the chemical structure of the polymer or its mixtures and more precisely of the alternatives that can be entered into the conjugated system or π system to obtain a material that besides to be flexible, environmentally stable, presents the colored states. The revision was centred chiefly in the polypyrrole (Ppy), the polythiophene (PTh) and their derivatives such as poly (3.4-ethylenedioxythiophene) (PEDOT). The advantage of using monomers with variable structure, to adjust the composition of the copolymer, or to blend with the PC, allows to obtain a variety of colored states that can be modulated through the visible spectrum and even with applications to wavelengths outside of this region. Because the PC presented at least two different colored states can be varied continuously as a function of the voltage applied. In some cases, they may submit multicoloured statements, which offers a range of possibilities for their application in flexible electronic devices type screens and windows. Applications include smart windows, camouflage clothing and data screens. This type of material is emerging as one of the substitutes of the traditional inorganic semiconductor, with the advantage of its low cost, high flexibility and the possibility to generate multiple colors through the handling of the monomers in the structure and control of energy of his band gap. (author) [es

Polarized Emission from Conjugated Polymer Chains Aligned by Epitaxial Growth during Off-Center Spin-Coating

Directory of Open Access Journals (Sweden)

Takuya Anzai

2017-01-01

Full Text Available Due to their macromolecular nature, conjugated polymers can be relatively easily aligned by applying a variety of processes resulting in either elongation or ordering of their conjugated backbones. Processes that induce chain alignment include electrospinning, mechanical rubbing, epitaxial growth, and nanoconfinement and unidirectional deposition techniques such as off-center spin-coating. In this study, we compare these deposition techniques by applying them to a green-emitting conjugated polymer material that exhibits liquid crystalline phase behavior. Our study reveals that while methods such as electrospinning and mechanical rubbing can be useful to locally generate polymer chain alignment, the combination of epitaxial growth using 1,3,5-trichlorobenzene as crystallizing agent with off-center spin-coating results in the formation of anisotropic nanofiber-like structures with enhanced crystallinity degree and polarized light-emission properties. The unidirectional epitaxial growth was also applied to a red-emitting polymer that exhibits polarization ratios up to 4.1. Our results emphasize that this simple solution formulation and process can be used for the fabrication of polarized thin films of a variety of conjugated polymers with potential applications in the advanced display technologies or analytical equipment fields.

Singlet Exciton Lifetimes in Conjugated Polymer Films for Organic Solar Cells

KAUST Repository

Dimitrov, Stoichko

2016-01-13

The lifetime of singlet excitons in conjugated polymer films is a key factor taken into account during organic solar cell device optimization. It determines the singlet exciton diffusion lengths in polymer films and has a direct impact on the photocurrent generation by organic solar cell devices. However, very little is known about the material properties controlling the lifetimes of singlet excitons, with most of our knowledge originating from studies of small organic molecules. Herein, we provide a brief summary of the nature of the excited states in conjugated polymer films and then present an analysis of the singlet exciton lifetimes of 16 semiconducting polymers. The exciton lifetimes of seven of the studied polymers were measured using ultrafast transient absorption spectroscopy and compared to the lifetimes of seven of the most common photoactive polymers found in the literature. A plot of the logarithm of the rate of exciton decay vs. the polymer optical bandgap reveals a medium correlation between lifetime and bandgap, thus suggesting that the Energy Gap Law may be valid for these systems. This therefore suggests that small bandgap polymers can suffer from short exciton lifetimes, which may limit their performance in organic solar cell devices. In addition, the impact of film crystallinity on the exciton lifetime was assessed for a small bandgap diketopyrrolopyrrole co-polymer. It is observed that the increase of polymer film crystallinity leads to reduction in exciton lifetime and optical bandgap again in agreement with the Energy Gap Law.

Synthesis, Characterization, and Biodistribution of Quantum Dot-Celecoxib Conjugate in Mouse Paw Edema Model

Directory of Open Access Journals (Sweden)

Suresh K. Kalangi

2018-01-01

Full Text Available Increased risk of cardiovascular side effects has been reported with many of the drugs in the market, including nonsteroidal anti-inflammatory drugs (NSAIDs. Hence, it is critical to thoroughly evaluate the biodistribution and pharmacokinetic properties of the drugs. Presently nanotechnology in combination with noninvasive imaging techniques such as magnetic resonance imaging (MRI, computed axial tomography (CAT, and positron emission tomography (PET provides a better estimate of the spatio-temporal distribution of therapeutic molecules. Optical imaging using quantum dot- (QD- tagged biological macromolecules is emerging as a fast, economical, sensitive, and safer alternative for theranostic purposes. In the present study, we report the nanoconjugates of mercaptopropionic acid- (MPA- capped CdTe quantum dots (QDs and Celecoxib for bio-imaging in carrageenan-induced mouse paw edema model of inflammation. QD-Celecoxib conjugates were characterized by fluorescence, FT-IR, NMR, and zeta-potential studies. In vivo imaging of QD-Celecoxib conjugates showed clear localization in the inflamed tissue of mouse paw within 3 h, with a gradual increase reaching a maximum and a later decline. This decrease of fluorescence in the paw region is followed by an increase in urinary bladder region, suggesting the possible excretion of QD-drug conjugates from mice within 24 h.

Vinyl Flanked Difluorobenzothiadiazole-Dithiophene Conjugated Polymer for High Performance Organic Field-Effect Transistors.

Energy Technology Data Exchange (ETDEWEB)

Liang, Xianfeng; Sun, Wandong; Chen, Yanlin; Tan, Luxi; Cai, Zheng-Xu; Liu, Zitong; Wang, Lin; Li, Jing; Chen, Wei; Dong, Lichun

2018-02-21

Fluorine containing conjugated polymers have been widely applied in high performance organic solar cells, but their use in field-effect transistors is still quite limited. In this work, a conjugated polymer PTFBTV based on difluorobenzothiadiazole (DFBT) and dithiophene was synthesized, utilizing multiple vinylene as linkers. The polymer exhibits a relatively high hole mobility up to 2.0 cm(2) V-1 s(-1) compared with the reported DFBT-oligothiophene based polymers, yet its structural complexity is much simpler. The polymer thin film exhibits a typical 'face on' molecular orientation. A single crystal of its monomer revealed a non-covalent intramolecular contact between fluorine and the neighbouring proton, which strengthens the backbone co-planarity. Meanwhile an intermolecular F...F contact was also observed, which might cause rather scattered lamellar crystallinity for PTFBTV in the solid state.

Conjugated Polymers and Oligomers: Structural and Soft Matter Aspects

DEFF Research Database (Denmark)

This book identifies modern topics and current trends of structural and soft matter aspects of conjugated polymers and oligomers. Each chapter recognizes an active research line where structural perspective dominates research and therefore the book covers fundamental aspects of persistent...

Photoinduced FT-IR spectroscopy and CW-photocurrent measurements of conjugated polymers and fullerenes blended into a conventional polymer matrix

NARCIS (Netherlands)

Brabec, C.J.; Johannson, H.; Padinger, F.; Neugebauer, H.; Hummelen, J.C.; Sariciftci, N.S.

2000-01-01

In this work we present an investigation of the photoexcited states in conjugated polymer (donor) - fullerene (acceptor) interpenetrating networks embedded into conventional polymer hosts like polystyrene (PS), polyvinylcarbazole (PVK) or polyvinylbenzylchloride (PVBC) (guest - host approach), using

Delocalization Drives Free Charge Generation in Conjugated Polymer Films

Energy Technology Data Exchange (ETDEWEB)

Rumbles, Garry [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Reid, Obadiah G [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pace, Natalie A [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-02-19

We demonstrate that the product of photoinduced electron transfer between a conjugated polymer host and a dilute molecular sensitizer is controlled by the structural state of the polymer. Ordered semicrystalline solids exhibit free charge generation, while disordered polymers in the melt phase do not. We use photoluminescence (PL) and time-resolved microwave conductivity (TRMC) measurements to sweep through polymer melt transitions in situ. Free charge generation measured by TRMC turns off upon melting, whereas PL quenching of the molecular sensitizers remains constant, implying unchanged electron transfer efficiency. The key difference is the intermolecular order of the polymer host in the solid state compared to the melt. We propose that this order-disorder transition modulates the localization length of the initial charge-transfer state, which controls the probability of free charge formation.

Laterally Ordered Bulk Heterojunction of Conjugated Polymers : Nanoskiving a Jelly Roll

NARCIS (Netherlands)

Lipomi, Darren J.; Chiechi, Ryan C.; Reus, William F.; Whitesides, George M.

2008-01-01

This paper describes the fabrication of a nanostructured heterojunction of two conjugated polymers by a three-step process: i) spin-coating a multilayered film of the two polymers, ii) rolling the film into a cylinder (a ‘‘jelly roll’’) and iii) sectioning the film perpendicular to the axis of the

Entanglements in Conjugated Polymers

Science.gov (United States)

Xie, Renxuan; Lee, Youngmin; Aplan, Melissa; Caggiano, Nick; Gomez, Enrique; Colby, Ralph

Conjugated polymers, such as poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly-((9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(thiophen-5-yl)-2,1,3-benzothiadiazole]-2',2''-diyl) (PFTBT), are widely used as hole and electron transport materials in a variety of electronic devices. However, fundamental knowledge regarding chain entanglements and nematic-to-isotropic transition is still lacking and are crucial to maximize charge transport properties. A systematic melt rheology study on P3HT with various molecular weights and regio regularities was performed. We find that the entanglement molecular weight Me is 5.0 kg/mol for regiorandom P3HT, but the apparent Me for regioregular P3HT is significantly higher. The difference is postulated to arise from the presence of a nematic phase only in regioregular P3HT. Analogously, PFTBT shows a clear rheological signature of the nematic-to-isotropic transition as a reversible sharp transition at 278 C. Shearing of this nematic phase leads to anisotropic crystalline order in PFTBT. We postulate that aligning the microstructure will impact charge transport and thereby advance the field of conducting polymers. National Science Foundation.

Sensitivity-Enhancement of FRET Immunoassays by Multiple-Antibody Conjugation on Quantum Dots.

Science.gov (United States)

Annio, Giacomo; Jennings, Travis; Tagit, Oya; Hildebrandt, Niko

2018-05-23

Quantum dots (QDs) are not only advantageous for color-tuning, improved brightness, and high stability, but their nanoparticle surfaces also allow for the attachment of many biomolecules. Because IgG antibodies (ABs) are in the same size range of biocompatible QDs and the AB orientation after conjugation to the QD is often random, it is difficult to predict if few or many ABs per QD will lead to an efficient AB-QD conjugate. This is particularly true for homogeneous Förster resonance energy transfer (FRET) sandwich immunoassays, for which the ABs on the QD must bind a biomarker that needs to bind a second AB-FRET-conjugate. Here, we investigate the performance of Tb-to-QD FRET immunoassays against total prostate specific antigen (TPSA) by changing the number of ABs per QD while leaving all the other assay components unchanged. We first characterize the AB-QD conjugation by various spectroscopic, microscopic, and chromatographic techniques and then quantify the TPSA immunoassay performance regarding sensitivity, limit of detection, and dynamic range. Our results show that an increasing conjugation ratio leads to significantly enhanced FRET immunoassays. These findings will be highly important for developing QD-based immunoassays in which the concentrations of both ABs and QDs can significantly influence the assay performance.

Synthesis and photocatalytic activity of TiO2/conjugated polymer complex nanoparticles

Institute of Scientific and Technical Information of China (English)

Shi Xiong Min; Fang Wang; Lei Feng; Yong Chun Tong; Zi Rong Yang

2008-01-01

A photocatalyst of nanometer TiO2/conjugated polymer complex was successfully synthesized and characterized by spectroscopic methods and photocatalytic experiments. The complex photocatalyst could be activated by absorbing both ultraviolet and visible light (λ=190-800nm). Methylene blue (MB) could be degraded more efficiently on the complex photocatalyst than on the TiO2 under natural light. The conjugated polymer played a promoting role in the photocatalytic degradation of MB. The calcination temperature had an important effect in degradation of dye and could be summarized as 260℃＞300℃＞340℃＞220℃＞180℃.

Asymmetric diketopyrrolopyrrole conjugated polymers for field-effect transistors and polymer solar cells processed from a non-chlorinated solvent

NARCIS (Netherlands)

Ji, Y.; Xiao, C.; Wang, Q.; Zhang, J.; Li, C.; Wu, Y.; Wei, Z.; Zhan, X.; Hu, W.; Wang, Z.; Janssen, R.A.J.; Li, W.W.

2016-01-01

Newly designed asymmetric diketopyrrolopyrrole conjugated polymers with two different aromatic substituents possess a hole mobility of 12.5 cm2 V−1 s−1 in field-effect transistors and a power conversion efficiency of 6.5% in polymer solar cells, when solution processed from a nonchlorinated

Conjugated Quantum Dots Inhibit the Amyloid β (1–42 Fibrillation Process

Directory of Open Access Journals (Sweden)

Garima Thakur

2011-01-01

Full Text Available Nanoparticles have enormous potential in diagnostic and therapeutic studies. We have demonstrated that the amyloid beta mixed with and conjugated to dihydrolipoic acid- (DHLA capped CdSe/ZnS quantum dots (QDs of size approximately 2.5 nm can be used to reduce the fibrillation process. Transmission electron microscopy (TEM and atomic force microscopy (AFM were used as tools for analysis of fibrillation. There is a significant change in morphology of fibrils when amyloid β (1–42 (Aβ (1–42 is mixed or conjugated to the QDs. The length and the width of the fibrils vary under modified conditions. Thioflavin T (ThT fluorescence supports the decrease in fibril formation in presence of DHLA-capped QDs.

Photoluminescence quenching through resonant energy transfer in blends of conjugated polymer with low-molecular acceptor

International Nuclear Information System (INIS)

Zapunidi, S. A.; Paraschuk, D. Yu.

2008-01-01

A model is proposed for photoluminescence quenching due to resonant energy transfer in a blend of a conjugated polymer and a low-molecular energy acceptor. An analytical dependence of the normalized photoluminescence intensity on the acceptor concentration is derived for the case of a homogeneous blend. This dependence can be described by two fitting parameters related to the Foerster radii for energy transfer between conjugated segments of the polymer and between the conjugated polymer segment and the energy acceptor. Asymptotic approximations are obtained for the model dependence that make it possible to estimate the contribution from the spatial migration of excitons to the photoluminescence quenching. The proposed model is used to analyze experimental data on the photoluminescence quenching in a blend of the soluble derivative of poly(p-phenylene vinylene) and trinitrofluorenone [13]. The Foerster radius for resonant energy transfer between the characteristic conjugated segment of poly(p-phenylene vinylene) and the energy acceptor is determined to be r F = 2.6 ± 0.3 nm

A general relationship between disorder, aggregation and charge transport in conjugated polymers

KAUST Repository

Noriega, Rodrigo; Rivnay, Jonathan; Vandewal, Koen; Koch, Felix P. V.; Stingelin, Natalie; Smith, Paul; Toney, Michael F.; Salleo, Alberto

2013-01-01

Conjugated polymer chains have many degrees of conformational freedom and interact weakly with each other, resulting in complex microstructures in the solid state. Understanding charge transport in such systems, which have amorphous and ordered phases exhibiting varying degrees of order, has proved difficult owing to the contribution of electronic processes at various length scales. The growing technological appeal of these semiconductors makes such fundamental knowledge extremely important for materials and process design. We propose a unified model of how charge carriers travel in conjugated polymer films. We show that in high-molecular-weight semiconducting polymers the limiting charge transport step is trapping caused by lattice disorder, and that short-range intermolecular aggregation is sufficient for efficient long-range charge transport. This generalization explains the seemingly contradicting high performance of recently reported, poorly ordered polymers and suggests molecular design strategies to further improve the performance of future generations of organic electronic materials. © 2013 Macmillan Publishers Limited. All rights reserved.

A general relationship between disorder, aggregation and charge transport in conjugated polymers

KAUST Repository

Noriega, Rodrigo

2013-08-04

Conjugated polymer chains have many degrees of conformational freedom and interact weakly with each other, resulting in complex microstructures in the solid state. Understanding charge transport in such systems, which have amorphous and ordered phases exhibiting varying degrees of order, has proved difficult owing to the contribution of electronic processes at various length scales. The growing technological appeal of these semiconductors makes such fundamental knowledge extremely important for materials and process design. We propose a unified model of how charge carriers travel in conjugated polymer films. We show that in high-molecular-weight semiconducting polymers the limiting charge transport step is trapping caused by lattice disorder, and that short-range intermolecular aggregation is sufficient for efficient long-range charge transport. This generalization explains the seemingly contradicting high performance of recently reported, poorly ordered polymers and suggests molecular design strategies to further improve the performance of future generations of organic electronic materials. © 2013 Macmillan Publishers Limited. All rights reserved.

Effects of π-conjugation attenuation on the photophysics and exciton dynamics of poly(p-phenylenevinylene) polymers incorporating 2,2'-bipyridines

International Nuclear Information System (INIS)

Chen, L. X.; Jager, W. J.; Niemczyk, M. P.; Wasielewski, M. R.

1999-01-01

The effect of π-conjugation attenuation on the photophysics and exciton dynamics of two conjugated polymers 1 and 2 are examined in solution. The structures of polymers 1 and 2 have 2,2'-bipyridyl-5-vinylene units that alternate with one and three 2,5-bis(n-decyloxy)-1,4-phenylenevinylene monomer units, respectively. The photophysics and exciton dynamics of polymers 1 and 2 were compared to those of the homopolymer, poly(2,5-bis(2'-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV). A series of changes in the photophysics of polymers 1 and 2 were found as a result of π-conjugation attenuation. These changes include blue shifts in absorption and emission spectra, spectral diffusion in stimulated emission, enhancement in photoluminescence quantum yields and lifetimes, and increases in photoinduced absorption intensities and lifetimes. These changes are systematically more pronounced in polymer 1 than in polymer 2 and are correlated with π-conjugation attenuation in the polymers due to twisting of the 2,2'-bipyridine groups about the 2,2' single bond. An exciton dynamics model involving an ensemble of initial exciton states localized on oligomeric segments within the polymer with different conjugation lengths is proposed to describe the observed differences between polymers 1 and 2 and BEH-PPV. When the electronic coupling between these segments is strong, the polymer displays characteristics that are close to those of a one-dimensional semiconductor. However, when these couplings are weakened by groups, such as the 2,2'-bipyridine that attenuate π-conjugation, the polymer displays properties of an ensemble of oligomers

Sulfur and Nitrogen co-doped graphene quantum dot decorated ZnO nanorod/polymer hybrid flexible device for photosensing applications

Energy Technology Data Exchange (ETDEWEB)

Hmar, Jehova Jire L.; Majumder, Tanmoy; Dhar, Saurab; Mondal, Suvra Prakash, E-mail: suvraphy@gmail.com

2016-08-01

S and N co-doped graphene quantum dots (S,N-GQDs) have been synthesized by a hydrothermal process. S,N-GQDs are made up of 1–5 monolayer of graphene with average diameter 13.3 nm. The absorption peaks at 336 and 621 nm, are attributed to n → Π{sup ⁎} transitions of electrons in C=O and S=O bonds, respectively. S,N-GQDs are highly luminescent and showed excitation dependent emission behaviors. Hybrid photosensing device has been fabricated with S,N-GQD sensitized ZnO nanorods and a conjugated polymer poly(3-hexylthiophene) (P3HT). S,N-GQD decorated ZnO nanorod demonstrated higher photoresponse compared to pristine ZnO nanorod based device. S,N-GQD/ZnO nanorod hybrid device showed superior incident photon to electron conversion efficiency (IPCE), photoresponsivity and detectivity compared to the control samples. The flexibility study of the samples has been monitored by measuring current-voltage characteristics at different bending angles. - Highlights: • S and N co-doped graphene quantum dots (S,N-GQDs) were synthesized. • ZnO nanorods were grown on ITO coated flexible PET substrates. • S,N-GQDs were attached with ZnO nanorods and used as a green sensitizer. • Photosensing properties of S,N-GQD/ZnO and P3HT polymer hybrid device was studied.

Non-Fullerene Polymer Solar Cells Based on Alkylthio and Fluorine Substituted 2D-Conjugated Polymers Reach 9.5% Efficiency.

Science.gov (United States)

Bin, Haijun; Zhang, Zhi-Guo; Gao, Liang; Chen, Shanshan; Zhong, Lian; Xue, Lingwei; Yang, Changduk; Li, Yongfang

2016-04-06

Non-fullerene polymer solar cells (PSCs) with solution-processable n-type organic semiconductor (n-OS) as acceptor have seen rapid progress recently owing to the synthesis of new low bandgap n-OS, such as ITIC. To further increase power conversion efficiency (PCE) of the devices, it is of a great challenge to develop suitable polymer donor material that matches well with the low bandgap n-OS acceptors thus providing complementary absorption and nanoscaled blend morphology, as well as suppressed recombination and minimized energy loss. To address this challenge, we synthesized three medium bandgap 2D-conjugated bithienyl-benzodithiophene-alt-fluorobenzotriazole copolymers J52, J60, and J61 for the application as donor in the PSCs with low bandgap n-OS ITIC as acceptor. The three polymers were designed with branched alkyl (J52), branched alkylthio (J60), and linear alkylthio (J61) substituent on the thiophene conjugated side chain of the benzodithiophene (BDT) units for studying effect of the substituents on the photovoltaic performance of the polymers. The alkylthio side chain, red-shifted absorption down-shifted the highest occupied molecular orbital (HOMO) level and improved crystallinity of the 2D conjugated polymers. With linear alkylthio side chain, the tailored polymer J61 exhibits an enhanced JSC of 17.43 mA/cm(2), a high VOC of 0.89 V, and a PCE of 9.53% in the best non-fullerene PSCs with the polymer as donor and ITIC as acceptor. To the best of our knowledge, the PCE of 9.53% is one of the highest values reported in literature to date for the non-fullerene PSCs. The results indicate that J61 is a promising medium bandgap polymer donor in non-fullerene PSCs.

Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor–Acceptor Conjugated Polymers

KAUST Repository

Ayzner, Alexander L.; Mei, Jianguo; Appleton, Anthony; DeLongchamp, Dean; Nardes, Alexandre; Benight, Stephanie; Kopidakis, Nikos; Toney, Michael F.; Bao, Zhenan

2015-01-01

© 2015 American Chemical Society. Conjugated polymers are widely used materials in organic photovoltaic devices. Owing to their extended electronic wave functions, they often form semicrystalline thin films. In this work, we aim to understand whether distribution of crystallographic orientations affects exciton diffusion using a low-band-gap polymer backbone motif that is representative of the donor/acceptor copolymer class. Using the fact that the polymer side chain can tune the dominant crystallographic orientation in the thin film, we have measured the quenching of polymer photoluminescence, and thus the extent of exciton dissociation, as a function of crystal orientation with respect to a quenching substrate. We find that the crystallite orientation distribution has little effect on the average exciton diffusion length. We suggest several possibilities for the lack of correlation between crystallographic texture and exciton transport in semicrystalline conjugated polymer films.

Impact of the Crystallite Orientation Distribution on Exciton Transport in Donor–Acceptor Conjugated Polymers

KAUST Repository

Ayzner, Alexander L.

2015-12-30

© 2015 American Chemical Society. Conjugated polymers are widely used materials in organic photovoltaic devices. Owing to their extended electronic wave functions, they often form semicrystalline thin films. In this work, we aim to understand whether distribution of crystallographic orientations affects exciton diffusion using a low-band-gap polymer backbone motif that is representative of the donor/acceptor copolymer class. Using the fact that the polymer side chain can tune the dominant crystallographic orientation in the thin film, we have measured the quenching of polymer photoluminescence, and thus the extent of exciton dissociation, as a function of crystal orientation with respect to a quenching substrate. We find that the crystallite orientation distribution has little effect on the average exciton diffusion length. We suggest several possibilities for the lack of correlation between crystallographic texture and exciton transport in semicrystalline conjugated polymer films.

A novel fluorescent retrograde neural tracer: cholera toxin B conjugated carbon dots

Science.gov (United States)

Zhou, Nan; Hao, Zeyu; Zhao, Xiaohuan; Maharjan, Suraj; Zhu, Shoujun; Song, Yubin; Yang, Bai; Lu, Laijin

2015-09-01

The retrograde neuroanatomical tracing method is a key technique to study the complex interconnections of the nervous system. Traditional tracers have several drawbacks, including time-consuming immunohistochemical or immunofluorescent staining procedures, rapid fluorescence quenching and low fluorescence intensity. Carbon dots (CDs) have been widely used as a fluorescent bio-probe due to their ultrasmall size, excellent optical properties, chemical stability, biocompatibility and low toxicity. Herein, we develop a novel fluorescent neural tracer: cholera toxin B-carbon dot conjugates (CTB-CDs). It can be taken up and retrogradely transported by neurons in the peripheral nervous system of rats. Our results show that CTB-CDs possess high photoluminescence intensity, good optical stability, a long shelf-life and non-toxicity. Tracing with CTB-CDs is a direct and more economical way of performing retrograde labelling experiments. Therefore, CTB-CDs are reliable fluorescent retrograde tracers.The retrograde neuroanatomical tracing method is a key technique to study the complex interconnections of the nervous system. Traditional tracers have several drawbacks, including time-consuming immunohistochemical or immunofluorescent staining procedures, rapid fluorescence quenching and low fluorescence intensity. Carbon dots (CDs) have been widely used as a fluorescent bio-probe due to their ultrasmall size, excellent optical properties, chemical stability, biocompatibility and low toxicity. Herein, we develop a novel fluorescent neural tracer: cholera toxin B-carbon dot conjugates (CTB-CDs). It can be taken up and retrogradely transported by neurons in the peripheral nervous system of rats. Our results show that CTB-CDs possess high photoluminescence intensity, good optical stability, a long shelf-life and non-toxicity. Tracing with CTB-CDs is a direct and more economical way of performing retrograde labelling experiments. Therefore, CTB-CDs are reliable fluorescent retrograde

A two-dimensional conjugated aromatic polymer via C-C coupling reaction

Science.gov (United States)

Liu, Wei; Luo, Xin; Bao, Yang; Liu, Yan Peng; Ning, Guo-Hong; Abdelwahab, Ibrahim; Li, Linjun; Nai, Chang Tai; Hu, Zhi Gang; Zhao, Dan; Liu, Bin; Quek, Su Ying; Loh, Kian Ping

2017-06-01

The fabrication of crystalline 2D conjugated polymers with well-defined repeating units and in-built porosity presents a significant challenge to synthetic chemists. Yet they present an appealing target because of their desirable physical and electronic properties. Here we report the preparation of a 2D conjugated aromatic polymer synthesized via C-C coupling reactions between tetrabromopolyaromatic monomers. Pre-arranged monomers in the bulk crystal undergo C-C coupling driven by endogenous solid-state polymerization to produce a crystalline polymer, which can be mechanically exfoliated into micrometre-sized lamellar sheets with a thickness of 1 nm. Isothermal gas-sorption measurements of the bulk material reveal a dominant pore size of ~0.6 nm, which indicates uniform open channels from the eclipsed stacking of the sheets. When employed as an organic anode in an ambient-temperature sodium cell, the material allows a fast charge/discharge of sodium ions, with impressive reversible capacity, rate capability and stability metrics.

Rapid, facile synthesis of conjugated polymer zwitterions in ionic liquids

Energy Technology Data Exchange (ETDEWEB)

Page, Zachariah A. [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Liu, Feng [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Russell, Thomas P. [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA; Emrick, Todd [Polymer Science & Engineering Department; Conte Center for Polymer Research; University of Massachusetts; Amherst, USA

2014-01-01

Ionic liquids (ILs) were utilized for the rapid air-stable Suzuki polymerization of polar zwitterionic thiophene monomers, precluding the need for volatile organic solvents, phosphine ligands and phase transfer catalysts typically used in conjugated polymer synthesis.

A Triphenylamine-Based Conjugated Polymer with Donor-π-Acceptor Architecture as Organic Sensitizer for Dye-Sensitized Solar Cells.

Science.gov (United States)

Zhang, Wei; Fang, Zhen; Su, Mingjuan; Saeys, Mark; Liu, Bin

2009-09-17

A conjugated polymer containing an electron donating backbone (triphenylamine) and an electron accepting side chain (cyanoacetic acid) with conjugated thiophene units as the linkers has been synthesized. Dye-sensitized solar cells (DSSCs) are fabricated utilizing this material as the dye sensitizer, resulting a typical power conversion efficiency of 3.39% under AM 1.5 G illumination, which represents the highest efficiency for polymer dye-sensitized DSSCs reported so far. The results show the good promise of conjugated polymers as sensitizers for DSSC applications. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of oligonucleic acid (ONA) backbone features on assembly of ONA-star polymer conjugates: a coarse-grained molecular simulation study.

Science.gov (United States)

Condon, Joshua E; Jayaraman, Arthi

2017-10-04

Understanding the impact of incorporating new physical and chemical features in oligomeric DNA mimics, termed generally as "oligonucleic acids" (ONAs), on their structure and thermodynamics will be beneficial in designing novel materials for a variety of applications. In this work, we conduct coarse-grained molecular simulations of ONA-star polymer conjugates with varying ONA backbone flexibility, ONA backbone charge, and number of arms in the star polymer at a constant ONA strand volume fraction to elucidate the effect of these design parameters on the thermodynamics and assembly of multi-arm ONA-star polymer conjugates. We quantify the thermo-reversible behavior of the ONA-star polymer conjugates by quantifying the hybridization of the ONA strands in the system as a function of temperature (i.e. melting curve). Additionally, we characterize the assembly of the ONA-star polymer conjugates by tracking cluster formation and percolation as a function of temperature, as well as cluster size distribution at temperatures near the assembly transition region. The key results are as follows. The melting temperature (T m ) of the ONA strands decreases upon going from a neutral to a charged ONA backbone and upon increasing flexibility of the ONA backbone. Similar behavior is seen for the assembly transition temperature (T a ) with varying ONA backbone charge and flexibility. While the number of arms in the ONA-star polymer conjugate has a negligible effect on the ONA T m in these systems, as the number of ONA-star polymer arms increase, the assembly temperature T a increases and local ordering in the assembled state improves. By understanding how factors like ONA backbone charge, backbone flexibility, and ONA-star polymer conjugate architecture impact the behavior of ONA-star polymer conjugate systems, we can better inform how the selection of ONA chemistry will influence resulting ONA-star polymer assembly.

Solvent-dependent self-assembly and ordering in slow-drying semi-crystalline conjugated polymer solutions

KAUST Repository

Zhao, Kui

2015-09-07

The mechanistic understanding of the intrinsic molecular self-assembly of conjugated polymers is of immense importance to controlling the microstructure development in organic semiconducting thin films, with meaningful impact on charge transport and optoelectronic properties. Yet, to date the vast majority of studies have focused on the fast solution process itself, with studies of slower intrinsic molecular self-assembly in formulations lagging behind. Here we have investigated molecular self-assembly during spontaneous organization and uncovered how changes in formulation influence the microstructure, morphology and transport properties of conjugated polymer thin films. Our results suggest that the polymer-solvent interaction is the key factor for the molecular self-assembly and changes in macroscopic charge transport, which is in contrast with most solution processes, such as spin-coating and blade coating, where solvent drying kinetics dominates the aggregation and crystallization processes. Energetically favourable interactions between the polymer and its solvent are shown to cause chain expansion, resulting in a large hydrodynamic volume and few chain entanglements in solution. This provides molecular freedom for self-assembly and is shown to greatly enhance the local and long range order of the polymer, intra-chain backbone planarity and crystallite size. These improvements, in turn, are shown to endow the conjugated polymer with high carrier transport, as demonstrated by organic thin film transistors.

Hybrid zinc oxide conjugated polymer bulk heterojunction solar cells

NARCIS (Netherlands)

Beek, W.J.E.; Wienk, M.M.; Kemerink, M.; Yang, X.N.; Janssen, R.A.J.

2005-01-01

Bulk heterojunction photovoltaic devices based on blends of a conjugated polymer poly[2-methoxy-5-(3‘,7‘-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) as electron donor and crystalline ZnO nanoparticles (nc-ZnO) as electron acceptor have been studied. Composite nc-ZnO:MDMO-PPV films were cast

Ultrasensitive Detection of Proteins on Western Blots with Semiconducting Polymer Dots

OpenAIRE

Ye, Fangmao; Smith, Polina B.; Wu, Changfeng; Chiu, Daniel T.

2013-01-01

We demonstrate ultrasensitive fluorescence imaging of proteins on Western blots using a bright, compact, and orange-emitting semiconducting polymer dot (CN-PPV). We achieved a detection limit at the single-picogram level in dot blots; with conventional Western blotting, we detected 50 pg of transferrin and trypsin inhibitor after SDS-PAGE and transfer onto a PVDF membrane. Our method does not require any additional equipment or time compared to the conventional procedure with traditional fluo...

Exploration of a Doxorubicin-Polymer Conjugate in Lipid-Polymer Hybrid Nanoparticle Drug Delivery

Science.gov (United States)

Lough, Emily

Nanoparticle (NP) drug delivery is a major focus in the research community because of its potential to use existing drugs in safer and more effective ways. Chemotherapy encapsulation in NPs shields the drug from the rest of the body while it is within the NP, with less systemic exposure leading to fewer off-target effects of the drug. However, passive loading of drugs into NPs is a suboptimal method, often leading to burst release upon administration. This work explores the impact of incorporating the drug-polymer conjugate doxorubicin-poly (lactic-co-glycolic) acid (Dox-PLGA) into a lipid-polymer hybrid nanoparticle (LPN). The primary difference in using a drug-polymer conjugate for NP drug delivery is the drug's release kinetics. Dox-PLGA LPNs showed a more sustained and prolonged release profile over 28 days compared to LPNs with passively loaded, unconjugated doxorubicin. This sustained release translates to cytotoxicity; when systemic circulation was simulated using dialysis, Dox-PLGA LPNs retained their cytotoxicity at a higher level than the passively loaded LPNs. The in vivo implication of preserving cytotoxic potency through a slower release profile is that the majority of Dox delivered via Dox-PLGA LPNs will be kept within the LPN until it reaches the tumor. This will result in fewer systemic side effects and more effective treatments given the higher drug concentration at the tumor site. An intriguing clinical application of this drug delivery approach lies in using Dox-PLGA LPNs to cross the blood-brain barrier (BBB). The incorporation of Dox-PLGA is hypothesized to have a protective effect on the BBB as its slow release profile will prevent drug from harming the BBB. Using induced pluripotent stem cells differentiated to human brain microvascular endothelial cells that comprise the BBB, the Dox-PLGA LPNs were shown to be less destructive to the BBB than their passively loaded counterparts. Dox-PLGA LPNs showed superior cytotoxicity against plated tumor

Molecular Orientation of Conjugated Polymer Chains in Nanostructures and Thin Films: Review of Processes and Application to Optoelectronics

Directory of Open Access Journals (Sweden)

Varun Vohra

2017-01-01

Full Text Available Semiconducting polymers are composed of elongated conjugated polymer backbones and side chains with high solubility and mechanical properties. The combination of these two features results in a high processability and a potential to orient the conjugated backbones in thin films and nanofibers. The thin films and nanofibers are usually composed of highly crystalline (high charge transport and amorphous parts. Orientation of conjugated polymer can result in enhanced charge transport or optical properties as it induces increased crystallinity or preferential orientation of the crystallites. After summarizing the potential strategies to exploit molecular order in conjugated polymer based optoelectronic devices, we will review some of the fabrication processes to induce molecular orientation. In particular, we will review the cases involving molecular and interfacial interactions, unidirectional deposition processes, electrospinning, and postdeposition mechanical treatments. The studies presented here clearly demonstrate that process-controlled molecular orientation of the conjugated polymer chains can result in high device performances (mobilities over 40 cm2·V−1·s−1 and solar cells with efficiencies over 10%. Furthermore, the peculiar interactions between molecularly oriented polymers and polarized light have the potential not only to generate low-cost and low energy consumption polarized light sources but also to fabricate innovative devices such as solar cell integrated LCDs or bipolarized LEDs.

Improving the in vivo therapeutic index of siRNA polymer conjugates through increasing pH responsiveness.

Science.gov (United States)

Guidry, Erin N; Farand, Julie; Soheili, Arash; Parish, Craig A; Kevin, Nancy J; Pipik, Brenda; Calati, Kathleen B; Ikemoto, Nori; Waldman, Jacob H; Latham, Andrew H; Howell, Bonnie J; Leone, Anthony; Garbaccio, Robert M; Barrett, Stephanie E; Parmar, Rubina Giare; Truong, Quang T; Mao, Bing; Davies, Ian W; Colletti, Steven L; Sepp-Lorenzino, Laura

2014-02-19

Polymer based carriers that aid in endosomal escape have proven to be efficacious siRNA delivery agents in vitro and in vivo; however, most suffer from cytotoxicity due in part to a lack of selectivity for endosomal versus cell membrane lysis. For polymer based carriers to move beyond the laboratory and into the clinic, it is critical to find carriers that are not only efficacious, but also have margins that are clinically relevant. In this paper we report three distinct categories of polymer conjugates that improve the selectivity of endosomal membrane lysis by relying on the change in pH associated with endosomal trafficking, including incorporation of low pKa heterocycles, acid cleavable amino side chains, or carboxylic acid pH sensitive charge switches. Additionally, we determine the therapeutic index of our polymer conjugates in vivo and demonstrate that the incorporation of pH responsive elements dramatically expands the therapeutic index to 10-15, beyond that of the therapeutic index (less than 3), for polymer conjugates previously reported.

Effect of disorder on exciton dissociation in conjugated polymers

International Nuclear Information System (INIS)

Feng Yuwen; Zhao Hui; Chen Yuguang; Yan Yonghong

2017-01-01

By using a multi-configurational time-dependent Hartree–Fock (MCTDHF) method for the time-dependent Schrödinger equation and a Newtonian equation of motion for lattice, we investigate the disorder effects on the dissociation process of excitons in conjugated polymer chains. The simulations are performed within the framework of an extended version of the Su–Schrieffer–Heeger model modified to include on-site disorder, off-diagonal, electron–electron interaction, and an external electric field. Our results show that Coulomb correlation effects play an important role in determining the exciton dissociation process. The electric field required to dissociate an exciton can practically impossibly occur in a pure polymer chain, especially in the case of triplet exciton. However, when the on-site disorder effects are taken into account, this leads to a reduction in mean dissociation electric fields. As the disorder strength increases, the dissociation field decreases effectively. On the contrary, the effects of off-diagonal disorder are negative in most cases. Moreover, the dependence of exciton dissociation on the conjugated length is also discussed. (paper)

The optical and electrical properties of graphene oxide with water-soluble conjugated polymer composites by radiation.

Science.gov (United States)

Jungo, Seung Tae; Oh, Seung-Hwan; Kim, Hyun Bin; Jeun, Joon-Pyo; Lee, Bum-Jae; Kang, Phil-Hyun

2013-11-01

In order to overcome the difficulty of dispersion and low conductivity in composite containing graphene, graphene oxide (GO) has been used instead of neat graphene. And the GO treated by radiation, could give improved conductivity of the GO-containing polymer composite. In this study, fluorene based water-soluble conjugated polymer (WPF-6-oxy-F) was introduced in GO solution to investigate the change of optical and electrical properties through radiation process. UV-Vis absorption of irradiated WPF-6-oxy-F-GO composite was red shifted and I(D)/I(G) ratio of Raman spectra decreased. XPS analysis showed that C-N bonds was formed after the irradiation and confirmed the increased bonds between the GO and the water-soluble conjugated polymer matrix. From the AFM and XPS analysis, it was found that the water-soluble conjugated polymer matrix was stacked between the modified GO in the morphology of irradiated WPF-6-oxy-F-GO composite was increased after gamma ray irradiation up to 10(-2) S/cm.

Impact of morphology on polaron delocalization in a semicrystalline conjugated polymer

KAUST Repository

Steyrleuthner, Robert; Zhang, Yuexing; Zhang, Lei; Kraffert, Felix; Cherniawski, Benjamin P.; Bittl, Robert; Briseno, Alejandro L.; Bredas, Jean-Luc; Behrends, Jan

2016-01-01

We investigate the delocalization of holes in the semicrystalline conjugated polymer poly(2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene) (PBTTT) by directly measuring the hyperfine coupling between photogenerated polarons and bound nuclear

Performance enhancement of quantum dot-sensitized solar cells based on polymer nano-composite catalyst

International Nuclear Information System (INIS)

Seo, Hyunwoong; Gopi, Chandu V.V.M.; Kim, Hee-Je; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

2017-01-01

Highlights: •We studied polymer nano-composite containing TiO 2 nano-particles as a catalyst. •Polymer nano-composite was applied for quantum dot-sensitized solar cells. •Polymer nano-composite catalyst was considerably improved with TiO 2 nano-particles. •Polymer nano-composite showed higher photovoltaic performance than conventional Au. -- Abstract: Polymer nano-composite composed of poly(3,4-ethylenedioxythiophene):poly (styrenesulfonate) and TiO 2 nano-particles was deposited on fluorine-doped tin oxide substrate and applied as an alternative to Au counter electrode of quantum dot-sensitized solar cell (QDSC). It became surface-richer with the increase in nano-particle amount so that catalytic reaction was increased by widened catalytic interface. Electrochemical impedance spectroscopy and cyclic voltammetry clearly demonstrated the enhancement of polymer nano-composite counter electrode. A QDSC based on polymer nano-composite counter electrode showed 0.56 V of V OC , 12.24 mA cm −2 of J SC , 0.57 of FF, and 3.87% of efficiency and this photovoltaic performance was higher than that of QDSC based on Au counter electrode (3.75%).

Dual-Color Fluorescence Imaging of Magnetic Nanoparticles in Live Cancer Cells Using Conjugated Polymer Probes

Science.gov (United States)

Sun, Minjie; Sun, Bin; Liu, Yun; Shen, Qun-Dong; Jiang, Shaojun

2016-01-01

Rapid growth in biological applications of nanomaterials brings about pressing needs for exploring nanomaterial-cell interactions. Cationic blue-emissive and anionic green-emissive conjugated polymers are applied as dual-color fluorescence probes to the surface of negatively charged magnetic nanoparticles through sequentially electrostatic adsorption. These conjugated polymers have large extinction coefficients and high fluorescence quantum yield (82% for PFN and 62% for ThPFS). Thereby, one can visualize trace amount (2.7 μg/mL) of fluorescence-labeled nanoparticles within cancer cells by confocal laser scanning microscopy. Fluorescence labeling by the conjugated polymers is also validated for quantitative determination of the internalized nanoparticles in each individual cell by flow cytometry analysis. Extensive overlap of blue and green fluorescence signals in the cytoplasm indicates that both conjugated polymer probes tightly bind to the surface of the nanoparticles during cellular internalization. The highly charged and fluorescence-labeled nanoparticles non-specifically bind to the cell membranes, followed by cellular uptake through endocytosis. The nanoparticles form aggregates inside endosomes, which yields a punctuated staining pattern. Cellular internalization of the nanoparticles is dependent on the dosage and time. Uptake efficiency can be enhanced three-fold by application of an external magnetic field. The nanoparticles are low cytotoxicity and suitable for simultaneously noninvasive fluorescence and magnetic resonance imaging application. PMID:26931282

Photovoltaic properties of conjugated polymer/fullerene composites on large area flexible substrates

Directory of Open Access Journals (Sweden)

Desta Gebeyehu

2000-06-01

Full Text Available In this paper we present measurements of the photovoltaic response of bulk donor-acceptor heterojunction between the conjugated polymer, poly(3-octylthiophene, P3OT, (as a donor, D and fullerene (methanofullerene, (as acceptor, A, deposited between indium tin oxide and aluminum electrodes. The innovation involves the substrate, which is a polymer foil instead of glass. These devices are based on ultrafast, reversible, metastable photoinduced electron transfer and charge separation. We also present the efficiency and stability studies on large area (6 cm x 6 cm flexible plastic solar cells with monochromatic energy conversion efficiency (e of about 1.5% and carrier collection efficiency of nearly 20%. Further more, we have investigated the surface network morphology of these films layers by atomic force microscope (AFM. The development of solar cells based on composites of organic conjugated semi-conducting polymers with fullerene derivatives can provide a new method in the exploitation of solar energy.

Ultrafast intersystem-crossing in platinum containing π-conjugated polymers with tunable spin-orbit coupling.

Science.gov (United States)

Sheng, C-X; Singh, S; Gambetta, A; Drori, T; Tong, M; Tretiak, S; Vardeny, Z V

2013-01-01

The development of efficient organic light-emitting diodes (OLED) and organic photovoltaic cells requires control over the dynamics of spin sensitive excitations. Embedding heavy metal atoms in π-conjugated polymer chains enhances the spin-orbit coupling (SOC), and thus facilitates intersystem crossing (ISC) from the singlet to triplet manifolds. Here we use various nonlinear optical spectroscopies such as two-photon absorption and electroabsorption in conjunction with electronic structure calculations, for studying the energies, emission bands and ultrafast dynamics of spin photoexcitations in two newly synthesized π-conjugated polymers that contain intrachain platinum (Pt) atoms separated by one (Pt-1) or three (Pt-3) organic spacer units. The controllable SOC in these polymers leads to a record ISC time of white OLEDs.

First-principles calculation of optical absorption spectra in conjugated polymers: Role of electron-hole interaction

International Nuclear Information System (INIS)

Rohlfing, Michael; Tiago, M.L.; Louie, Steven G.

2000-01-01

Experimental and theoretical studies have shown that excitonic effects play an important role in the optical properties of conjugated polymers. The optical absorption spectrum of trans-polyacetylene, for example, can be understood as completely dominated by the formation of exciton bound states. We review a recently developed first-principles method for computing the excitonic effects and optical spectrum, with no adjustable parameters. This theory is used to study the absorption spectrum of two conjugated polymers: trans-polyacetylene and poly-phenylene-vinylene(PPV)

First-principles calculation of optical absorption spectra in conjugated polymers: Role of electron-hole interaction

Energy Technology Data Exchange (ETDEWEB)

Rohlfing, Michael; Tiago, M.L.; Louie, Steven G.

2000-03-20

Experimental and theoretical studies have shown that excitonic effects play an important role in the optical properties of conjugated polymers. The optical absorption spectrum of trans-polyacetylene, for example, can be understood as completely dominated by the formation of exciton bound states. We review a recently developed first-principles method for computing the excitonic effects and optical spectrum, with no adjustable parameters. This theory is used to study the absorption spectrum of two conjugated polymers: trans-polyacetylene and poly-phenylene-vinylene(PPV).

Particle-in-a-box model of one-dimensional excitons in conjugated polymers

Science.gov (United States)

Pedersen, Thomas G.; Johansen, Per M.; Pedersen, Henrik C.

2000-04-01

A simple two-particle model of excitons in conjugated polymers is proposed as an alternative to usual highly computationally demanding quantum chemical methods. In the two-particle model, the exciton is described as an electron-hole pair interacting via Coulomb forces and confined to the polymer backbone by rigid walls. Furthermore, by integrating out the transverse part, the two-particle equation is reduced to one-dimensional form. It is demonstrated how essentially exact solutions are obtained in the cases of short and long conjugation length, respectively. From a linear combination of these cases an approximate solution for the general case is obtained. As an application of the model the influence of a static electric field on the electron-hole overlap integral and exciton energy is considered.

Direct measurement of the microscale conductivity of conjugated polymer monolayers

DEFF Research Database (Denmark)

Bøggild, Peter; Grey, Francois; Hassenkam, T.

2000-01-01

The in-plane conductivity of conjugated polymer monolayers is mapped here for the first time on the microscale using a novel scanning micro four-point probe (see Figure). The probe allows the source, drain, and voltage electrodes to be positioned within the same domain and the mapping results...

Theoretical and computational studies of excitons in conjugated polymers

Science.gov (United States)

Barford, William; Bursill, Robert J.; Smith, Richard W.

2002-09-01

We present a theoretical and computational analysis of excitons in conjugated polymers. We use a tight-binding model of π-conjugated electrons, with 1/r interactions for large r. In both the weak-coupling limit (defined by W>>U) and the strong-coupling limit (defined by Wparticle models. We compare these to density matrix renormalization group (DMRG) calculations, and find good agreement in the extreme limits. We use these analytical results to interpret the DMRG calculations in the intermediate-coupling regime (defined by W~U), most applicable to conjugated polymers. We make the following conclusions. (1) In the weak-coupling limit the bound states are Mott-Wannier excitons, i.e., conduction-band electrons bound to valence-band holes. Singlet and triplet excitons whose relative wave functions are odd under a reflection of the relative coordinate are degenerate. Thus, the 2 1A+g and 1 3A-g states are degenerate in this limit. (2) In the strong-coupling limit the bound states are Mott-Hubbard excitons, i.e., particles in the upper Hubbard band bound to holes in the lower Hubbard band. These bound states occur in doublets of even and odd parity excitons. Triplet excitons are magnons bound to the singlet excitons, and hence are degenerate with their singlet counterparts. (3) In the intermediate-coupling regime Mott-Wannier excitons are the more appropriate description for large dimerization, while for the undimerized chain Mott-Hubbard excitons are the correct description. For dimerizations relevant to polyacetylene and polydiacetylene both Mott-Hubbard and Mott-Wannier excitons are present. (4) For all coupling strengths an infinite number of bound states exist for 1/r interactions for an infinite polymer. As a result of the discreteness of the lattice and the restrictions on the exciton wave functions in one dimension, the progression of states does not follow the Rydberg series. In practice, excitons whose particle-hole separation exceeds the length of the polymer

Dye sensitized photovoltaic cells: Attaching conjugated polymers to zwitterionic ruthenium dyes

DEFF Research Database (Denmark)

Krebs, Frederik C; Biancardo, M.

2006-01-01

The synthesis of a zwitterionic ruthenium dye that binds to anatase surfaces and has a built-in functionality that allows for the attachment of a conjugated polymer chain is presented. The system was found to adsorb on the surface of anatase anchored by the ruthenium dye. Two types of devices were...... prepared: standard photoelectrochemical (PEC) solar cells and polymer solar cells. The PEC solar cells employed a sandwich geometry between TiO2 nanoporous photoanodes and Pt counter electrodes using LiI/I-2 in CH3CN as an electrolyte. The polymer solar cells employed planar anatase electrodes...

Multifunctional SA-PProDOT Binder for Lithium Ion Batteries.

Science.gov (United States)

Ling, Min; Qiu, Jingxia; Li, Sheng; Yan, Cheng; Kiefel, Milton J; Liu, Gao; Zhang, Shanqing

2015-07-08

An environmentally benign, highly conductive, and mechanically strong binder system can overcome the dilemma of low conductivity and insufficient mechanical stability of the electrodes to achieve high performance lithium ion batteries (LIBs) at a low cost and in a sustainable way. In this work, the naturally occurring binder sodium alginate (SA) is functionalized with 3,4-propylenedioxythiophene-2,5-dicarboxylic acid (ProDOT) via a one-step esterification reaction in a cyclohexane/dodecyl benzenesulfonic acid (DBSA)/water microemulsion system, resulting in a multifunctional polymer binder, that is, SA-PProDOT. With the synergetic effects of the functional groups (e.g., carboxyl, hydroxyl, and ester groups), the resultant SA-PProDOT polymer not only maintains the outstanding binding capabilities of sodium alginate but also enhances the mechanical integrity and lithium ion diffusion coefficient in the LiFePO4 (LFP) electrode during the operation of the batteries. Because of the conjugated network of the PProDOT and the lithium doping under the battery environment, the SA-PProDOT becomes conductive and matches the conductivity needed for LiFePO4 LIBs. Without the need of conductive additives such as carbon black, the resultant batteries have achieved the theoretical specific capacity of LiFePO4 cathode (ca. 170 mAh/g) at C/10 and ca. 120 mAh/g at 1C for more than 400 cycles.

The Curious Case of Fluorination of Conjugated Polymers for Solar Cells.

Science.gov (United States)

Zhang, Qianqian; Kelly, Mary Allison; Bauer, Nicole; You, Wei

2017-09-19

Organic solar cells (OSCs) have been a rising star in the field of renewable energy since the introduction of the bulk heterojunction (BHJ) in 1992. Recent advances have pushed the efficiencies of OSCs to over 13%, an impressive accomplishment via collaborative efforts in rational materials design and synthesis, careful device engineering, and fundamental understanding of device physics. Throughout these endeavors, several design principles for the conjugated donor polymers used in such solar cells have emerged, including optimizing the conjugated backbone with judicious selection of building blocks, side-chain engineering, and substituents. Among all of the substituents, fluorine is probably the most popular one; improved device characteristics with fluorination have frequently been reported for a wide range of conjugated polymers, in particular, donor-acceptor (D-A)-type polymers. Herein we examine the effect of fluorination on the device performance of solar cells as a function of the position of fluorination (on the acceptor unit or on the donor unit), aiming to outline a clear understanding of the benefits of this curious substituent. As fluorination of the acceptor unit is the most adopted strategy for D-A polymers, we first discuss the effect of fluorination of the acceptor units, highlighting the five most widely utilized acceptor units. While improved device efficiency has been widely observed with fluorinated acceptor units, the underlying reasons vary from case to case and highly depend on the chemical structure of the polymer. Second, the effect of fluorination of the donor unit is addressed. Here we focus on four donor units that have been most studied with fluorination. While device-performance-enhancing effects by fluorination of the donor units have also been observed, it is less clear that fluorine will always benefit the efficiency of the OSC, as there are several cases where the efficiency drops, in particular with "over-fluorination", i.e., when

Photonic effects in microstructured conjugated polymer films and light emitting diodes

International Nuclear Information System (INIS)

Matterson, B.J.

2002-03-01

This thesis reports an investigation into the photonic effects caused by wavelength scale microstructure patterned onto films of conjugated polymers. The efficiency of light emitting diodes (LEDs) made from conjugated polymers is limited in part by the trapping of light into waveguide modes caused by the high refractive index of these materials. Waveguide modes in films of poly(p,-phenylene vinylene) (PPV) and poly(2-methoxy, 5-(2'ethylhexyloxy)-p-phenylene vinylene) (MEH-PPV) are analysed and the refractive index of these materials is calculated. The photoluminescence of conjugated polymer films that have been spun onto textured substrates is analysed. It is found that the photoluminescence quantum yield of a film spun onto a substrate inscribed with a grating is increased. It is also found that the photoluminescence spectrum of the film is dramatically altered and varies substantially with viewing angle. The features in the spectrum caused by the grating are strongly polarized. These effects are analysed and are attributed to the scattering of waveguided light out of the film. It is found that films spun onto metal gratings exhibit especially strong scattering. The effect of metal gratings with various grating depths is analysed. The possible contribution of band gaps to the photoluminescence spectrum from polymers on strong metal gratings is discussed. LEDs that include grating structures are constructed and analysed. It is found that having grating structures on the metal layers that are used as electrodes in the LED does not adversely affect the electrical properties of the LED. It is demonstrated that grating in the LED is able to substantially increase the light emission without using extra electrical power. The emission spectra from LEDs are observed to vary with angle, and exhibit considerable polarization. (author)

The mechanism of the photoluminescence changes in bio-conjugated CdSe/ZnS quantum dots

Science.gov (United States)

Borkovska, L.; Korsunska, N.; Stara, T.; Kolomys, O.; Strelchuk, V.; Rachkov, O.; Kryshtab, T.

2013-09-01

The change of the photoluminescence (PL) and optical characteristics in non-conjugated and conjugated with S6K2 antibody CdSe/ZnS core/shell quantum dots (QDs) during storage in air has been studied by the conventional PL, micro-PL and micro-Raman techniques. The QDs dried on a crystalline Si substrate were kept in the darkness and under illumination. In the PL spectra, the storage resulted in a blue shift of PL peak position, in the increasing of the full width at a half maximum (FWHM) of the PL band and in the decreasing of the PL intensity. In the Raman spectra, the shift of the CdSe LO peak position to the low frequency region and the increasing of its FWHM were observed. The transformations in the PL and optical characteristics correlate with each other and are found to be the largest in bio-conjugated QDs stored under illumination. The increase of the light intensity accelerated the changes occurred during storage. An oxidation of the QD core, which decreases the QD size, is supposed to be responsible for observed transformations. The bio-conjugation is assumed to promote QD oxidation that results in different PL peak position in stored non-conjugated and bio-conjugated QDs. The mechanism of the effect is discussed.

A Rapid Detection Method of Brucella with Quantum Dots and Magnetic Beads Conjugated with Different Polyclonal Antibodies

Science.gov (United States)

Song, Dandan; Qu, Xiaofeng; Liu, Yushen; Li, Li; Yin, Dehui; Li, Juan; Xu, Kun; Xie, Renguo; Zhai, Yue; Zhang, Huiwen; Bao, Hao; Zhao, Chao; Wang, Juan; Song, Xiuling; Song, Wenzhi

2017-03-01

Brucella spp. are facultative intracellular bacteria that cause zoonotic disease of brucellosis worldwide. Traditional methods for detection of Brucella spp. take 48-72 h that does not meet the need of rapid detection. Herein, a new rapid detection method of Brucella was developed based on polyclonal antibody-conjugating quantum dots and antibody-modified magnetic beads. First, polyclonal antibodies IgG and IgY were prepared and then the antibody conjugated with quantum dots (QDs) and immunomagnetic beads (IMB), respectively, which were activated by N-(3-dimethylaminopropyl)- N'-ethylcar-bodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to form probes. We used the IMB probe to separate the Brucella and labeled by the QD probe, and then detected the fluorescence intensity with a fluorescence spectrometer. The detection method takes 105 min with a limit of detection of 103 CFU/mL and ranges from 10 to 105 CFU/mL ( R 2 = 0.9983), and it can be well used in real samples.

Hydrophilic Conjugated Polymers with Large Bandgaps and Deep-Lying HOMO Levels as an Efficient Cathode Interlayer in Inverted Polymer Solar Cells.

Science.gov (United States)

Kan, Yuanyuan; Zhu, Yongxiang; Liu, Zhulin; Zhang, Lianjie; Chen, Junwu; Cao, Yong

2015-08-01

Two hydrophilic conjugated polymers, PmP-NOH and PmP36F-NOH, with polar diethanol-amine on the side chains and main chain structures of poly(meta-phenylene) and poly(meta-phenylene-alt-3,6-fluorene), respectively, are successfully synthesized. The films of PmP-NOH and PmP36F-NOH show absorption edges at 340 and 343 nm, respectively. The calculated optical bandgaps of the two polymers are 3.65 and 3.62 eV, respectively, the largest ones so far reported for hydrophilic conjugated polymers. PmP-NOH and PmP36F-NOH also possess deep-lying highest occupied molecular orbital levels of -6.19 and -6.15 eV, respectively. Inserting PmP-NOH and PmP36F-NOH as a cathode interlayer in inverted polymer solar cells with a PTB7/PC71 BM blend as the active layer, high power conversion efficiencies of 8.58% and 8.33%, respectively, are achieved, demonstrating that the two hydrophilic polymers are excellent interlayers for efficient inverted polymer solar cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quantum-Dot-Based Theranostic Micelles Conjugated with an Anti-EGFR Nanobody for Triple-Negative Breast Cancer Therapy.

Science.gov (United States)

Wang, Yuyuan; Wang, Yidan; Chen, Guojun; Li, Yitong; Xu, Wei; Gong, Shaoqin

2017-09-13

A quantum-dot (QD)-based micelle conjugated with an anti-epidermal growth factor receptor (EGFR) nanobody (Nb) and loaded with an anticancer drug, aminoflavone (AF), has been engineered for EGFR-overexpressing cancer theranostics. The near-infrared (NIR) fluorescence of the indium phosphate core/zinc sulfide shell QDs (InP/ZnS QDs) allowed for in vivo nanoparticle biodistribution studies. The anti-EGFR nanobody 7D12 conjugation improved the cellular uptake and cytotoxicity of the QD-based micelles in EGFR-overexpressing MDA-MB-468 triple-negative breast cancer (TNBC) cells. In comparison with the AF-encapsulated nontargeted (i.e., without Nb conjugation) micelles, the AF-encapsulated Nb-conjugated (i.e., targeted) micelles accumulated in tumors at higher concentrations, leading to more effective tumor regression in an orthotopic triple-negative breast cancer xenograft mouse model. Furthermore, there was no systemic toxicity observed with the treatments. Thus, this QD-based Nb-conjugated micelle may serve as an effective theranostic nanoplatform for EGFR-overexpressing cancers such as TNBCs.

Amphibious fluorescent carbon dots: one-step green synthesis and application for light-emitting polymer nanocomposites.

Science.gov (United States)

Zhou, Li; He, Benzhao; Huang, Jiachang

2013-09-21

A facile and green approach for the synthesis of amphibious fluorescent carbon dots (CDs) from natural polysaccharide is reported. Light-emitting polymer nanocomposites with excellent optical performance can be easily prepared by incorporation of the amphibious CDs into the polymer matrix.

Structure-processing-property correlations in thin films of conjugated polymer nanocomposites and blends

Science.gov (United States)

Sreeram, Arvind

Conjugated polymers have found several applications in recent years, in energy conversion and storage devices such as organic light emitting diodes, solar cells, batteries, and super capacitors. Thin films of polymers used for these applications need to be mechanically and thermally stable to withstand the harsh operating conditions. Although there is significant information on the optoelectronic properties of many of these polymers, there are only few studies on their mechanical properties. There is little information in the literature on how processing of these films influence mechanical properties. In the first part of this study, poly(p-phenylene vinylene) (PPV) films were prepared by thermolytic conversion of poly[p -phenylene (tetrahydrothiophenium)ethylene chloride] precursor films, at different temperatures and the kinetics of reaction was investigated using thermogravimetry and Fourier transform infrared (FTIR) spectroscopy. The mechanical properties of the films, studied using nanoindentation, showed a dependence on the extent of conversion and chemical composition of the films. The presence of chemical defects (e.g., carbonyl groups, detected using FTIR spectroscopy), was also found to have a noticeable effect on the modulus and hardness of the films. The storage modulus, E', and plasticity decreased with an increase in conversion, whereas the loss modulus, E", showed the opposite trend. Both the precursor and the fully-converted PPV films were found to have significantly lower E" than E', consistent with the glassy nature of the polymers at room temperature. In the second part of the study, polyacetylene films were synthesized by acid-catalyzed dehydration reaction of poly(vinyl alcohol) (PVA) precursor films. The kinetics of this reaction was monitored by thermogravimetry. The chemical structure of the conjugated polymer films was characterized by Raman and IR spectroscopy. Polyacetylene films incorporated with 1-propyl-3-methylimidazolium ionic liquid

Molecular-weight dependence of interchain polaron delocalization and exciton bandwidth in high-mobility conjugated polymers

DEFF Research Database (Denmark)

Chang, J.F.; Clark, J.; Zhao, N.

2006-01-01

delocalization with increasing conjugation length and crystalline quality. From comparative studies of field-effect transistor characteristics, film morphology, and optical properties our study provides a microscopic understanding of the factors which limit the charge transport in P3HT to field-effect mobilities......Interchain interactions have a profound effect on the optical as well as charge transport properties of conjugated polymer thin films. In contrast to oligomeric model systems in solution-deposited polymer thin films the study of such effects is complicated by the complex microstructure. We present...

Photoluminescence properties of a novel conjugate of water-soluble CdTe quantum dots to guanine

Energy Technology Data Exchange (ETDEWEB)

Feng Xuejiao [North-East Normal University, Changchun 130024 (China); Shang, Qingkun, E-mail: shangqk995@nenu.edu.c [North-East Normal University, Changchun 130024 (China); Liu Hongjian [Relia Diagnostic Systems, Burlingame, CA 94010 (United States); Wang Wenlan; Wang Zhidan; Liu Junyu [North-East Normal University, Changchun 130024 (China)

2010-04-15

A novel conjugate of water-soluble CdTe quantum dots to a small biomolecule guanine has been obtained in aqueous phase. The photoluminescence property and the stability of the conjugate increased comparing to CdTe QDs. The interaction between CdTe QDs and guanine was studied by TEM, fluorescence microscope and photoluminescence (PL), IR, UV-Vis spectra. The effects of reflux time, pH value, ionic strength, and the ratio of CdTe QDs to guanine on the photoluminescence properties of conjugate were investigated in detail. The results show that guanine has a great influence on both the photoluminescence property and stability of thioglycolic acid-stabilized CdTe QDs. The formation of coordination and hydrogen bond between guanine molecules and CdTe including thioglycolic acid on its surface may effectively enhance the PL intensity and stability of CdTe QDs. The maximum PL intensity of the conjugate was obtained on the condition with lower ionic strength, less than 30 min reflux time, neutral pH value and 6/1 as molar ratio of guanine to CdTe.

New electroluminescent carbazole-containing conjugated polymer: synthesis, photophysics, and electroluminescence

Czech Academy of Sciences Publication Activity Database

Cimrová, Věra; Ulbricht, C.; Dzhabarov, Vagif; Výprachtický, Drahomír; Egbe, D. A. M.

2014-01-01

Roč. 55, č. 24 (2014), s. 6220-6226 ISSN 0032-3861 R&D Projects: GA ČR GAP106/12/0827; GA ČR(CZ) GA13-26542S Institutional support: RVO:61389013 Keywords : carbazole-containing conjugated polymer * synthesis * photophysics and electroluminescence Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.562, year: 2014

Synthesis and Characterisation of Biocompatible Polymer-Conjugated Magnetic Beads for Enhancement Stability of Urease.

Science.gov (United States)

Doğaç, Yasemin Ispirli; Teke, Mustafa

2016-04-01

We reported natural polymer-conjugated magnetic featured urease systems for removal of urea effectively. The optimum temperature (20-60 °C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4-70 °C), pH stability (4.0-9.0), operational stability (0-250 min), reusability (18 times) and storage stability (24 weeks) were studied for characterisation of the urease-encapsulated biocompatible polymer-conjugated magnetic beads. Also, the surface groups and chemical structure of the magnetic beads were determined by using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The all urease-encapsulated magnetic beads protected their stability of 30-45 % relative activity at 70 °C. A significant increase was observed at their pH stability compared with the free urease for both acidic and alkaline medium. Besides this, their repeatability activity were approximately 100 % during 4(th) run. They showed residual activity of 50 % after 16 weeks. The importance of this work is enhancement stability of immobilised urease by biocompatible polymer-conjugated magnetic beads for the industrial application based on removal of urea.

Comparison of eosin and fluorescein conjugates for the photoinitiation of cell-compatible polymer coatings.

Directory of Open Access Journals (Sweden)

Jacob L Lilly

Full Text Available Targeted photopolymerization is the basis for multiple diagnostic and cell encapsulation technologies. While eosin is used in conjunction with tertiary amines as a water-soluble photoinitiation system, eosin is not widely sold as a conjugate with antibodies and other targeting biomolecules. Here we evaluate the utility of fluorescein-labeled bioconjugates to photopolymerize targeted coatings on live cells. We show that although fluorescein conjugates absorb approximately 50% less light energy than eosin in matched photopolymerization experiments using a 530 nm LED lamp, appreciable polymer thicknesses can still be formed in cell compatible environments with fluorescein photosensitization. At low photoinitiator density, eosin allows more sensitive initiation of gelation. However at higher functionalization densities, the thickness of fluorescein polymer films begins to rival that of eosin. Commercial fluorescein-conjugated antibodies are also capable of generating conformal, protective coatings on mammalian cells with similar viability and encapsulation efficiency as eosin systems.

Comparison of eosin and fluorescein conjugates for the photoinitiation of cell-compatible polymer coatings.

Science.gov (United States)

Lilly, Jacob L; Gottipati, Anuhya; Cahall, Calvin F; Agoub, Mohamed; Berron, Brad J

2018-01-01

Targeted photopolymerization is the basis for multiple diagnostic and cell encapsulation technologies. While eosin is used in conjunction with tertiary amines as a water-soluble photoinitiation system, eosin is not widely sold as a conjugate with antibodies and other targeting biomolecules. Here we evaluate the utility of fluorescein-labeled bioconjugates to photopolymerize targeted coatings on live cells. We show that although fluorescein conjugates absorb approximately 50% less light energy than eosin in matched photopolymerization experiments using a 530 nm LED lamp, appreciable polymer thicknesses can still be formed in cell compatible environments with fluorescein photosensitization. At low photoinitiator density, eosin allows more sensitive initiation of gelation. However at higher functionalization densities, the thickness of fluorescein polymer films begins to rival that of eosin. Commercial fluorescein-conjugated antibodies are also capable of generating conformal, protective coatings on mammalian cells with similar viability and encapsulation efficiency as eosin systems.

Submicron polymer particles containing fluorescent semiconductor nanocrystals CdSe/ZnS for bioassays.

Science.gov (United States)

Generalova, Alla N; Sizova, Svetlana V; Zdobnova, Tatiana A; Zarifullina, Margarita M; Artemyev, Michail V; Baranov, Alexander V; Oleinikov, Vladimir A; Zubov, Vitaly P; Deyev, Sergey M

2011-02-01

This study aimed to design a panel of uniform particulate biochemical reagents and to test them in specific bioassays. These reagents are polymer particles of different sizes doped with semiconductor nanocrystals and conjugated with either full-size antibodies or recombinant mini-antibodies (4D5 scFv fragment) designed by genetic engineering approaches. A panel of highly fluorescent polymer particles (150-800 nm) were formed by embedding CdSe/ZnS nanocrystals (quantum dots) into preformed polyacrolein and poly(acrolein-co-styrene) particles. Morphology, content and fluorescence characteristics of the prepared materials were studied by laser correlation spectroscopy, spectrophotometry, optical and fluorescent microscopy and fluorimetry. The obtained fluorescent particles sensitized by anti-Yersinia pestis antibodies were used for rapid agglutination glass test suitable for screening analysis of Y. pestis antigen and for microtiter particle agglutination, which, owing to its speed and simplicity, is very beneficial for diagnostic detection of Y. pestis antigen. Recombinant 4D5 scFv antibodies designed and conjugated with polymer particles containing quantum dots provide multipoint highly specific binding with cancer marker HER2/neu on the surface of SKOV-3 cell.

Planar conjugated polymers containing 9,10-disubstituted phenanthrene units for efficient polymer solar cells.

Science.gov (United States)

Li, Guangwu; Kang, Chong; Li, Cuihong; Lu, Zhen; Zhang, Jicheng; Gong, Xue; Zhao, Guangyao; Dong, Huanli; Hu, Wenping; Bo, Zhishan

2014-06-01

Four novel conjugated polymers (P1-4) with 9,10-disubstituted phenanthrene (PhA) as the donor unit and 5,6-bis(octyloxy)benzothiadiazole as the acceptor unit are synthesized and characterized. These polymers are of medium bandgaps (2.0 eV), low-lying HOMO energy levels (below -5.3 eV), and high hole mobilities (in the range of 3.6 × 10(-3) to 0.02 cm(2) V(-1) s(-1) ). Bulk heterojunction (BHJ) polymer solar cells (PSCs) with P1-4:PC71 BM blends as the active layer and an alcohol-soluble fullerene derivative (FN-C60) as the interfacial layer between the active layer and cathode give the best power conversion efficiency (PCE) of 4.24%, indicating that 9,10-disubstituted PhA are potential donor materials for high-efficiency BHJ PSCs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interleukin-13 conjugated quantum dots for identification of glioma initiating cells and their extracellular vesicles.

Science.gov (United States)

Madhankumar, A B; Mrowczynski, Oliver D; Patel, Suhag R; Weston, Cody L; Zacharia, Brad E; Glantz, Michael J; Siedlecki, Christopher A; Xu, Li-Chong; Connor, James R

2017-08-01

Cadmium selenide (CdSe) based quantum dots modified with polyethylene glycol and chemically linked to interleukin-13 (IL13) were prepared with the aim of identifying the high affinity receptor (IL13Rα2) which is expressed in glioma stem cells and exosomes secreted by these cancer stem cells. IL13 conjugated quantum dots (IL13QD) were thoroughly characterized for their physicochemical properties including particle size and surface morphology. Furthermore, the specific binding of the IL13QD to glioma cells and to glioma stem cells (GSC) was verified using a competitive binding study. The exosomes were isolated from the GSC conditioned medium and the expression of IL13Rα2 in the GSC and exosomes was verified. The binding property of IL13QD to the tumor associated exosomes was initially confirmed by transmission electron microscopy. The force of attraction between the quantum dots and U251 glioma cells and the exosomes was investigated by atomic force microscopy, which indicated a higher force of binding interaction between the IL13QD and IL13Rα2 expressing glioma cells and exosomes secreted by glioma stem cells. Flow cytometry of the IL13QD and exosomes from the culture media and cerebrospinal fluid (CSF) of patients with glioma tumors indicated a distinctly populated complex pattern different from that of non-targeted quantum dots and bovine serum albumin (BSA) conjugated quantum dots confirming specific binding potential of the IL13QD to the tumor associated exosomes. The results of this study demonstrate that IL13QD can serve as an ex vivo marker for glioma stem cells and exosomes that can inform diagnosis and prognosis of patients harboring malignant disease. Functionalized quantum dots are flexible semiconductor nanomaterials which have an immense application in biomedical research. In particular, when they are functionalized with biomolecules like proteins or antibodies, they have the specialized ability to detect the expression of receptors and antigens in

Adaptive sliding mode control of tri-layer conjugated polymer actuators

International Nuclear Information System (INIS)

Wang, Xiangjiang; Alici, Gursel; Nguyen, Chuc Huu

2013-01-01

This paper proposes an adaptive sliding mode control methodology to enhance the positioning ability of conducting polymer actuators typified by tri-layer conjugated polymer actuators. This is motivated by the search for an effective control strategy to command such actuators to a desired configuration in the presence of parametric uncertainties and unmodeled disturbances. After analyzing the stability of the adaptive sliding mode control system, experiments were conducted to demonstrate its satisfactory tracking ability, based on a series of experimental results. Implementation of the control law requires a valid model of the conducting polymer actuator and boundaries of the uncertainties and disturbances. Based on the theoretical and experimental results presented, the adaptive sliding mode control methodology is very attractive in the field of smart actuators which contain significant uncertainties and disturbances. (paper)

Electro-Optical and Electrochemical Properties of a Conjugated Polymer Prepared by the Cyclopolymerization of Diethyl Dipropargylmalonate

Directory of Open Access Journals (Sweden)

Yeong-Soon Gal

2008-01-01

Full Text Available The electro-optical and electrochemical properties of poly(diethyl dipropargylmalonate were measured and discussed. Poly(diethyl dipropargylmalonate prepared by (NBDPdCl2 catalyst was used for study. The chemical structure of poly(diethyl dipropargylmalonate was characterized by such instrumental methods as NMR (1H-, 13C-, IR, and UV-visible spectroscopies to have the conjugated cyclopolymer backbone system. The microstructure analysis of polymer revealed that this polymer have the six-membered ring moieties majorly. The photoluminescence peak of polymer was observed at 543 nm, which is corresponded to the photon energy of 2.51 eV. The cyclovoltamograms of the polymer exhibited the irreversible electrochemical behaviors between the doping and undoping peaks. It was found that the kinetics of the redox process of this conjugated cyclopolymer might be controlled by the diffusion-control process from the experiment of the oxidation current density of polymer versus the scan rate.

Naphtho[1,2-b:5,6-b']dithiophene-Based Conjugated Polymers for Fullerene-Free Inverted Polymer Solar Cells.

Science.gov (United States)

Jiang, Zhaoyan; Li, Huan; Wang, Zhen; Zhang, Jianqi; Zhang, Yajie; Lu, Kun; Wei, Zhixiang

2018-03-23

Three novel copolymers based on zigzag naphthodithiophene (zNDT) with different aromatic rings as π bridges and different core side substitutions are designed and synthesized (PzNDT-T-1,3-bis(4-(2-ethylhexyl)-thiophen-2-yl)-5,7-bis(2-ethylhexyl)benzo[1,2-c:4,5-c']-dithiophene-4,8-dione (BDD), PzNDT-TT-BDD, and PzNDTP-T-BDD, respectively). The 2D conjugation structure and molecular planarity of the polymers can be effectively altered through the modification of conjugated side chains and π-bridges. These alterations contribute to the variation in energy levels, light absorption capacity, and morphology compatibility of the polymers. When blended with the nonfullerene acceptor (2,2'-[(4,4,9,9-tetrahexyl-4,9-dihydro-sindaceno[1,2-b:5,6-b']dithiophene-2,7-diyl)bis[methylidyne(3-oxo-1H-indene-2,1(3H)-diylidene)

Conjugated Polymers Containing BODIPY and Fluorene Units for Sensitive Detection of CN− Ions: Site-Selective Synthesis, Photo-Physical and Electrochemical Properties

Directory of Open Access Journals (Sweden)

Tian He

2017-10-01

Full Text Available Conjugated polymers containing distinct molecular units are expected to be very interesting because of their unique properties endowed by these units and the formed conjugated polymers. Herein, four new conjugated copolymers based on fluorene and 4,4’-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY have been designed and synthesized via Sonogashira polymerization. The fluorene unit was attached to the 3,5- or 2,6-positions of BODIPY by ethynylenes or p-diacetylenebenzene. The obtained polymers show good thermal stability and broad absorption in the wavelength range from 300 to 750 nm. The effects of site-selective copolymerization and conjugation length along the polymer backbone on the optoelectronic and electrochemical properties of these copolymers were systematically studied by UV-Vis spectroscopy, photoluminescence (PL and cyclic voltammetry. Besides, it is found that the BODIPY-based copolymers exhibit selectively sensitive responses to cyanide anions, resulting in obvious change of UV-Vis absorption spectra and significant fluorescence quenching of the polymers among various common anions.

Acyclic Diene Metathesis (ADMET Polymerization for Precise Synthesis of Defect-Free Conjugated Polymers with Well-Defined Chain Ends

Directory of Open Access Journals (Sweden)

Tahmina Haque

2015-03-01

Full Text Available This accounts introduces unique characteristics by adopting the acyclic diene metathesis (ADMET polymerization for synthesis of conjugated polymers, poly(arylene vinylenes, known as promising molecular electronics. The method is more suitable than the other methods in terms of atom efficiency affording defect-free, stereo-regular (exclusive trans polymers with well-defined chain ends; the resultant polymers possess better property than those prepared by the conventional methods. The chain ends (vinyl group in the resultant polymer prepared by ruthenium-carbene catalyst(s can be modified by treating with molybdenum-alkylidene complex (olefin metathesis followed by addition of various aldehyde (Wittig type cleavage, affording the end-functionalized polymers exclusively. An introduction of initiating fragment, the other conjugated segment, and one-pot synthesis of end-functionalized block copolymers, star shape polymers can be achieved by adopting this methodology.

Syntheses and optical properties of triphenylene-containing conjugated polymers

International Nuclear Information System (INIS)

Chou, C.-E.; Wang Degang; Bagui, Mahuya; Hsu, Jeffrey; Chakraborty, Sanjiban; Peng Zhonghua

2010-01-01

In this paper, we report the detailed synthesis and optical properties of three new conjugated polymers containing triphenylene units in the backbone. Polymer PTPT exhibits strong folding propensity and forms foldamers in both polar and nonpolar solvents. PTPA, with two long alkyl chains attached to the bridging phenyl ring, exhibits mainly as interchain aggregates in 'poor' solvents (DMSO and acetonitrile), but adopts a folding conformation in solvent mixtures with a high poor solvent content. PTPV, on the other hand, adopts a random nonfolding conformation in both polar and nonpolar solvents. The low folding propensity of PTPV is likely due to the added geometrical flexibility of the vinyl bonds. Among the three polymers, PTPV is most fluorescent with a fluorescence quantum yield as high as 0.87, suggesting its potential applications as light-emitting materials or fluorescence-based sensors. PTPT, on the other hand, with its strong folding property, may find applications as efficient charge-transporting materials.

Fine-tuning of electronic properties in donor-acceptor conjugated polymers based on oligothiophenes

Science.gov (United States)

Imae, Ichiro; Sagawa, Hitoshi; Harima, Yutaka

2018-03-01

A novel series of donor-acceptor conjugated polymers having oligothiophenes with well-defined structures were synthesized and their optical, electrochemical, and photovoltaic properties were investigated. It was found that the absorption bands of polymers were red-shifted with increasing number of ethylenedioxy groups added to each oligothiophene unit and that their band edges reached over 1000 nm. The systematical fine-tuning of the electronic properties was achieved using the chemical structures of oligothiophene units. Photovoltaic cells based on polymer/(6,6)-phenyl C61 butyric acid methyl ester (PC61BM) exhibited power conversion efficiencies in the range from 0.004 to 1.10%, reflecting the electronic properties of the polymers.

Nature of the Binding Interactions between Conjugated Polymer Chains and Fullerenes in Bulk Heterojunction Organic Solar Cells

KAUST Repository

Ravva, Mahesh Kumar; Wang, Tonghui; Bredas, Jean-Luc

2016-01-01

Blends of π-conjugated polymers and fullerene derivatives are ubiquitous as the active layers of organic solar cells. However, a detailed understanding of the weak noncovalent interactions at the molecular level between the polymer chains

Quantum dots and nanocomposites.

Science.gov (United States)

Mansur, Herman Sander

2010-01-01

Quantum dots (QDs), also known as semiconducting nanoparticles, are promising zero-dimensional advanced materials because of their nanoscale size and because they can be engineered to suit particular applications such as nonlinear optical devices (NLO), electro-optical devices, and computing applications. QDs can be joined to polymers in order to produce nanocomposites which can be considered a scientific revolution of the 21st century. One of the fastest moving and most exciting interfaces of nanotechnology is the use of QDs in medicine, cell and molecular biology. Recent advances in nanomaterials have produced a new class of markers and probes by conjugating semiconductor QDs with biomolecules that have affinities for binding with selected biological structures. The nanoscale of QDs ensures that they do not scatter light at visible or longer wavelengths, which is important in order to minimize optical losses in practical applications. Moreover, at this scale, quantum confinement and surface effects become very important and therefore manipulation of the dot diameter or modification of its surface allows the properties of the dot to be controlled. Quantum confinement affects the absorption and emission of photons from the dot. Thus, the absorption edge of a material can be tuned by control of the particle size. This paper reviews developments in the myriad of possibilities for the use of semiconductor QDs associated with molecules producing novel hybrid nanocomposite systems for nanomedicine and bioengineering applications.

Bipolar and Unipolar Silylene-Diphenylene σ-π Conjugated Polymer Route for Highly Efficient Electrophosphorescence

Science.gov (United States)

Chang, Yao-Tang; Sharma, Sunil; Hung, Miao-Ken; Lee, Yu-Hsuan; Chen, Show-An

2016-12-01

σ-π conjugated polymer strategy is proposed for designing electroluminescent host polymers with silylene-diphenylene as the backbone repeat unit giving a high triplet energy (ET = 2.67 eV). By incorporation of high ET (3.0 eV) electron (oxadiazole, OXD) and hole (triphenyl amine, TPA) transport moieties, or TPA alone (in this case, the main chain acts as electron transport channel) as side arms on the silylene, the high ET bipolar and unipolar polymers are formed, allowing a use of iridium green phosphor (Ir(ppy)2(acac), Ir-G) (ET = 2.40 eV) as the dopant. The matching of energy levels of the dopant with the hosts, leading to charge trapping into it; and singlets and triplets of the exciplex and excimer can be harvested via energy transfer to the dopant. Using these host-guest systems as the emitting layer, chlorinated indium-tin-oxide (Cl-ITO) as the anode, and benzimidazole derivative (TPBI) as the electron transport layer, this two-layer device gives the high luminance efficiency 80.1 cd/A and external quantum efficiency 21.2%, which is the best among the report values for polymer light emitting diode (PLED) in the literatures. This example manifests that σ-π conjugated polymer strategy is a promising route for designing polymer host for efficient electrophosphorescence.

Photoinduced charge transfer within polyaniline-encapsulated quantum dots decorated on graphene.

Science.gov (United States)

Nguyen, Kim Truc; Li, Dehui; Borah, Parijat; Ma, Xing; Liu, Zhaona; Zhu, Liangliang; Grüner, George; Xiong, Qihua; Zhao, Yanli

2013-08-28

A new method to enhance the stability of quantum dots (QDs) in aqueous solution by encapsulating them with conducting polymer polyaniline was reported. The polyaniline-encapsulated QDs were then decorated onto graphene through π-π interactions between graphene and conjugated polymer shell of QDs, forming stable polyaniline/QD/graphene hybrid. A testing electronic device was fabricated using the hybrid in order to investigate the photoinduced charge transfer between graphene and encapsulated QDs within the hybrid. The charge transfer mechanism was explored through cyclic voltammetry and spectroscopic studies. The hybrid shows a clear response to the laser irradiation, presenting a great advantage for further applications in optoelectronic devices.

Design, synthesis and photovoltaic properties of a series of new acceptor-pended conjugated polymers

Institute of Scientific and Technical Information of China (English)

Zhihong; Wu; Yongxiang; Zhu; Wei; Li; Yunping; Huang; Junwu; Chen; Chunhui; Duan; Fei; Huang; Yong; Cao

2016-01-01

A series of novel acceptor-pended conjugated polymers featuring a newly developed carbazole-derived unit are designed and synthesized. The relationships between chemical structure and optoelectronic properties of the polymers are systematically investigated.The control of UV-Vis absorption spectra and energy levels in resulting polymers are achieved by introducing suitable pended acceptor units. The photovoltaic properties of the resulting polymers are evaluated by blending the polymers with(6,6)-phenyl-C71-butyric acid methyl ester. The resulting solar cells exhibit moderate performances with high open-circuit voltage. Charge transport properties and morphology were investigated to understand the performance of corresponding solar cells.

Carrier heating in disordered conjugated polymers in electric field

Energy Technology Data Exchange (ETDEWEB)

Vukmirovic, Nenad; Wang, Lin-Wang

2010-01-26

The electric field dependence of charge carrier transport and the effect of carrier heating in disordered conjugated polymers were investigated. A parameter-free multiscale methodology consisting of classical molecular dynamics simulation for the generation of the atomic structure, large system electronic structure and electron-phonon coupling constants calculations and the procedure for extracting the bulk polymer mobility, was used. The results suggested that the mobility of a fully disordered poly(3-hexylthiophene) (P3HT) polymer increases with electric field which is consistent with the experimental results on samples of regiorandom P3HT and different from the results on more ordered regioregular P3HT polymers, where the opposite trend is often observed at low electric fields. We calculated the electric field dependence of the effective carrier temperature and showed however that the effective temperature cannot be used to replace the joint effect of temperature and electric field, in contrast to previous theoretical results from phenomenological models. Such a difference was traced to originate from the use of simplified Miller-Abrahams hopping rates in phenomenological models in contrast to our considerations that explicitly take into account the electronic state wave functions and the interaction with all phonon modes.

Control of gain in conjugated polymers and perylene dyes

International Nuclear Information System (INIS)

Sheridan, A.

2001-03-01

This thesis presents an investigation into the factors which control the gain and amplification properties in conjugated materials. Conjugated polymers and perylene dyes are highly fluorescent, are easy to process into thin films, and exhibit strong amplification over a broad gain bandwidth making them ideal for use in lasers and amplifiers. The stimulated emission created when thin films of the red emitting polymer poly(2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenvinylene) (MEH-PPV) were photoexcited with high energy laser pulses was investigated. This was characterised by a dramatic narrowing of the emission spectrum which has been assigned to amplified spontaneous emission (ASE). The emission was found to have a gaussian profile and the gain coefficient was found to be 4 cm -1 . The temperature dependence of the absorption, photoluminescence and ASE of films of MEH-PPV was measured. The effect of film morphology on the photophysical properties was investigated by using films cast from two spinning solvents, chlorobenzene (CB) and tetrahydrofuran (THF). Film morphology was found to greatly affect the temperature dependence. A particularly important property is the spectral position of the ASE and the factors which affect it. By controlling the film thickness close to the cut-off thickness for waveguiding in the polymer film it was shown that the peak position of the ASE could be tuned by 31 nm. Modelling of the waveguide modes in the polymer films was used to explain this effect. The cut-off wavelength for each film was measured and good agreement with the theory was found. In order to investigate ways in which energy transfer could be used to control the emission, two perylene dyes were used as a donor-acceptor pair in a host matrix of poly methymethacralate (PMMA). The position of the ASE was found to depend on the acceptor concentration. Measurements of the photoluminescence quantum yield and time-resolved luminescence measurements showed that the energy transfer

Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

KAUST Repository

Botiz, Ioan; Stingelin, Natalie

2014-01-01

It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties. © 2014 by the authors.

Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

Directory of Open Access Journals (Sweden)

Ioan Botiz

2014-03-01

Full Text Available It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties.

Influence of Molecular Conformations and Microstructure on the Optoelectronic Properties of Conjugated Polymers

KAUST Repository

Botiz, Ioan

2014-03-19

It is increasingly obvious that the molecular conformations and the long-range arrangement that conjugated polymers can adopt under various experimental conditions in bulk, solutions or thin films, significantly impact their resulting optoelectronic properties. As a consequence, the functionalities and efficiencies of resulting organic devices, such as field-effect transistors, light-emitting diodes, or photovoltaic cells, also dramatically change due to the close structure/property relationship. A range of structure/optoelectronic properties relationships have been investigated over the last few years using various experimental and theoretical methods, and, further, interesting correlations are continuously revealed by the scientific community. In this review, we discuss the latest findings related to the structure/optoelectronic properties interrelationships that exist in organic devices fabricated with conjugated polymers in terms of charge mobility, absorption, photoluminescence, as well as photovoltaic properties. © 2014 by the authors.

Charge carrier motion in disordered conjugated polymers: a multiscale ab-initio study

Energy Technology Data Exchange (ETDEWEB)

Vukmirovic, Nenad; Wang, Lin-Wang

2009-11-10

We developed an ab-initio multiscale method for simulation of carrier transport in large disordered systems, based on direct calculation of electronic states and electron-phonon coupling constants. It enabled us to obtain the never seen before rich microscopic details of carrier motion in conjugated polymers, which led us to question several assumptions of phenomenological models, widely used in such systems. The macroscopic mobility of disordered poly(3- hexylthiophene) (P3HT) polymer, extracted from our simulation, is in agreement with experimental results from the literature.

Solvent-dependent self-assembly and ordering in slow-drying semi-crystalline conjugated polymer solutions

KAUST Repository

Zhao, Kui; Yu, Xinhong; Li, Ruipeng; Amassian, Aram; Han, Yanchun

2015-01-01

The mechanistic understanding of the intrinsic molecular self-assembly of conjugated polymers is of immense importance to controlling the microstructure development in organic semiconducting thin films, with meaningful impact on charge transport

Bactericidal Specificity and Resistance Profile of Poly(Quaternary Ammonium) Polymers and Protein-Poly(Quaternary Ammonium) Conjugates.

Science.gov (United States)

Ji, Weihang; Koepsel, Richard R; Murata, Hironobu; Zadan, Sawyer; Campbell, Alan S; Russell, Alan J

2017-08-14

Antibacterial polymers are potentially powerful biocides that can destroy bacteria on contact. Debate in the literature has surrounded the mechanism of action of polymeric biocides and the propensity for bacteria to develop resistance to them. There has been particular interest in whether surfaces with covalently coupled polymeric biocides have the same mechanism of action and resistance profile as similar soluble polymeric biocides. We designed and synthesized a series of poly(quaternary ammonium) polymers, with tailorable molecular structures and architectures, to engineer their antibacterial specificity and their ability to delay the development of bacterial resistance. These linear poly(quaternary ammonium) homopolymers and block copolymers, generated using atom transfer radical polymerization, had structure-dependent antibacterial specificity toward Gram positive and negative bacterial species. When single block copolymers contained two polymer segments of differing antibacterial specificity, the polymer combined the specificities of its two components. Nanoparticulate human serum albumin-poly(quaternary ammonium) conjugates of these same polymers, synthesized via "grafting from" atom transfer radical polymerization, were strongly biocidal and also exhibited a marked decrease in the rate of bacterial resistance development relative to linear polymers. These protein-biocide conjugates mimicked the behavior of surface-presented polycationic biocides rather than their nonproteinaceous counterparts.

Application of Quantum Dots in Biological Imaging

Directory of Open Access Journals (Sweden)

Shan Jin

2011-01-01

Full Text Available Quantum dots (QDs are a group of semiconducting nanomaterials with unique optical and electronic properties. They have distinct advantages over traditional fluorescent organic dyes in chemical and biological studies in terms of tunable emission spectra, signal brightness, photostability, and so forth. Currently, the major type of QDs is the heavy metal-containing II-IV, IV-VI, or III-V QDs. Silicon QDs and conjugated polymer dots have also been developed in order to lower the potential toxicity of the fluorescent probes for biological applications. Aqueous solubility is the common problem for all types of QDs when they are employed in the biological researches, such as in vitro and in vivo imaging. To circumvent this problem, ligand exchange and polymer coating are proven to be effective, besides synthesizing QDs in aqueous solutions directly. However, toxicity is another big concern especially for in vivo studies. Ligand protection and core/shell structure can partly solve this problem. With the rapid development of QDs research, new elements and new morphologies have been introduced to this area to fabricate more safe and efficient QDs for biological applications.

Alcohol vapor sensory properties of nanostructured conjugated polymers

International Nuclear Information System (INIS)

Bearzotti, Andrea; Macagnano, Antonella; Pantalei, Simone; Zampetti, Emiliano; Venditti, Iole; Fratoddi, Ilaria; Vittoria Russo, Maria

2008-01-01

The response to relative humidity (RH) and alcohol vapors of resistive-type sensors based on nanobeads of conjugated polymers, namely polyphenylacetylene (PPA) and copolymer poly[phenylacetylene-(co-2-hydroxyethyl methacrylate)] (P(PA/HEMA)), were investigated. Sensors based on ordered arrays of these nanostructured polymeric materials showed stable and reproducible current intensity variations in the range 10-90% of relative humidity at room temperature. Both polymers also showed sensitivity to aliphatic chain primary alcohols, and a fine tuning of the sensor response was obtained by varying the chain length of the alcohol in relation to the polarity. The nanostructured feature of polymeric-based membranes seems to have an effect on the sensing response and an enhancement of the sensitivity was observed for the response to water and alcohol vapor variations with respect to previous studies based on amorphous polyphenylacetylene. High stability of the polymeric nanostructured membranes was detected with no aging after two weeks in continuum stressing measurement conditions.

Anthracene-containing wide-band-gap conjugated polymers for high-open-circuit-voltage polymer solar cells.

Science.gov (United States)

Gong, Xue; Li, Cuihong; Lu, Zhen; Li, Guangwu; Mei, Qiang; Fang, Tao; Bo, Zhishan

2013-07-25

The synthesis, characterization, and photophysical and photovoltaic properties of two anthracene-containing wide-band-gap donor and acceptor (D-A) alternating conjugated polymers (P1 and P2) are described. These two polymers absorb in the range of 300-600 nm with a band gap of about 2.12 eV. Polymer solar cells with P1:PC71 BM as the active layer demonstrate a power conversion efficiency (PCE) of 2.23% with a high Voc of 0.96 V, a Jsc of 4.4 mA cm(-2) , and a comparable fill factor (FF) of 0.53 under simulated solar illumination of AM 1.5 G (100 mW cm(-2) ). In addition, P2:PC71 BM blend-based solar cells exhibit a PCE of 1.42% with a comparable Voc of 0.89 V, a Jsc of 3.0 mA cm(-2) , and an FF of 0.53. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of Donor-Acceptor Conjugated Polymers by "CLICK" Polymerization for OPV applications

DEFF Research Database (Denmark)

Brandt, Rasmus Guldbæk; Yu, Donghong

The intent of this study was to utilize the Copper(I)-catalyzed Azide Alkyne Cycloaddition (CuAAC) as a polymerization technique (“Click” Polymerization) for synthesizing novel π-conjugated low band gap polymers for organic photovoltaic applications (OPV). The chosen approach was to synthesize...... an alternating electron donating (donor, D) and electron withdrawing (acceptor, A) co-polymer. The chosen monomers were well known units, and the novelty lies in using the monomer units with the click methodology. An insoluble alternating copolymer consisting of 2,7-diazido-9,9-dioctyl-9Hflourene and 1...

Stability issues of conjugated polymer / fullerene solar cells from a chemical viewpoint

NARCIS (Netherlands)

Hummelen, J.C.; Knol, J.; Sánchez, L.

2001-01-01

The efficiency of energy conversion and the stability or lifetime of ‘plastic’ photovoltaic cells, based on conjugated polymer/ fullerene blends, are the two main issues to be improved for this type of devices. The stability of these PV cells depends potentially on a large number of factors. A brief

Effects of chemical modifications on photophysics and exciton dynamics on {pi}-conjugation attenuated and metal-chelated photoconducting polymers

Energy Technology Data Exchange (ETDEWEB)

Chen, L. X.; Jager, W. J. H.; Gosztola, D. J.; Niemczyk, M. P.; Wasielewski, M. R.

2000-03-11

Effects of two types of chemical modifications on photoconducting polymers consisting of polyphenylenevinylene (PPV) derivatives are studied by static and ultrafast transient optical spectroscopy as well as semi-empirical ZINDO calculations. The first type of modification inserts 2,2{prime}-bipyridyl-5-vinylene units (bpy V) in the PPV backbone, and the second type involves metal-chelation with the bpy sites. Photoluminescence and exciton dynamics of polymers 1 and 2 with PV:bpyV ratios of 1 and 3 were examined in solution, and compared to those of the homopolymer, poly(2,5-bis(2{prime}-ethylhexyloxy)-1,4-phenylenevinylene) (BEH-PPV). Similar studies were carried out for several metal-chelated polymers. These results can be explained by changes in {pi}-conjugation throughout the polymer backbone. The attenuation in {pi}-conjugation by the chemical modifications transforms a conducting polymer from one-dimensional semiconductor to molecular aggregates.

Pluronic-lysozyme conjugates as anti-adhesive and antibacterial bifunctional polymers for surface coating

NARCIS (Netherlands)

Muszanska, A.K.; Busscher, H.J.; Herrmann, A.; Mei, van der H.C.; Norde, W.

2011-01-01

This paper describes the preparation and characterization of polymer protein conjugates composed of a synthetic triblock copolymer with a central polypropylene oxide (PPO) block and two terminal polyethylene oxide (PEO) segments, Pluronic F-127, and the antibacterial enzyme lysozyme attached to the

Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

KAUST Repository

Zhao, Kui; Khan, Hadayat Ullah; Li, Ruipeng; Hu, Hanlin; Amassian, Aram

2016-01-01

and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining

Synthesis and characterization of a low bandgap conjugated polymer for bulk heterojunction photovoltaic cells

NARCIS (Netherlands)

Dhanabalan, A.; Duren, van J.K.J.; Hal, van P.A.; Dongen, van J.L.J.; Janssen, R.A.J.

2001-01-01

Low optical bandgap conjugated polymers may improve the efficiency of organic photovoltaic devices by increasing the absorption in the visible and near infrared region of the solar spectrum. Here we demonstrate that condensation polymerization of

Theory of interfacial charge-transfer complex photophysics in π-conjugated polymer-fullerene blends

Science.gov (United States)

Aryanpour, K.; Psiachos, D.; Mazumdar, S.

2010-03-01

We present a theory of the electronic structure and photophysics of 1:1 blends of derivatives of polyparaphenylenevinylene and fullerenes [1]. Within the same Coulomb-correlated Hamiltonian applied previously to interacting chains of single-component π-conjugated polymers [2], we find an exciplex state that occurs below the polymer's optical exciton. Weak absorption from the ground state occurs to the exciplex. We explain transient photoinduced absorptions in the blend [3], observed for both above-gap and below-gap photoexcitations, within our theory. Photoinduced absorptions for above-gap photoexcitation are from the optical exciton as well as the exciplex, while for below-gap photoexcitation induced absorptions are from the exciplex alone. In neither case are free polarons generated in the time scale of the experiment. Importantly, the photophysics of films of single-component π-conjugated polymers and blends can both be understood by extending Mulliken's theory of ground state charge-transfer to the case of excited state charge-transfer. [1] K. Aryanpour, D. Psiachos, and S. Mazumdar, arXiv:0908.0366 [2] D. Psiachos and S. Mazumdar, Phys. Rev. B. 79 155106 (2009) [3] T. Drori et al., Phys. Rev. Lett. 101, 037402 (2008)

Impact of the Enhanced Permeability and Retention (EPR Effect and Cathepsins Levels on the Activity of Polymer-Drug Conjugates

Directory of Open Access Journals (Sweden)

Amit K. Rajora

2014-08-01

Full Text Available Polymer-drug conjugates have demonstrated clinical potential in the context of anticancer therapy. However, such promising results have, to date, failed to translate into a marketed product. Polymer-drug conjugates rely on two factors for activity: (i the presence of a defective vasculature, for passive accumulation of this technology into the tumour tissue (enhanced permeability and retention (EPR effect and (ii the presence of a specific trigger at the tumour site, for selective drug release (e.g., the enzyme cathepsin B. Here, we retrospectively analyse literature data to investigate which tumour types have proved more responsive to polymer-drug conjugates and to determine correlations between the magnitude of the EPR effect and/or expression of cathepsin B. Lung, breast and ovarian cancers showed the highest response rate (30%, 47% and 41%, respectively for cathepsin-activated conjugates and 31%, 43%, 40%, across all conjugates. An analysis of literature data on cathepsin content in various tumour types showed that these tumour types had high cathepsin content (up to 3835 ng/mg for lung cancer, although marked heterogeneity was observed across different studies. In addition, these tumour types were also reported as having a high EPR effect. Our results suggest that a pre-screening of patient population could bring a more marked clinical benefit.

Upconversion luminescent logic gates and turn-on sensing of glutathione based on two-photon excited quantum dots conjugated with dopamine.

Science.gov (United States)

Gui, Rijun; Jin, Hui; Liu, Xifeng; Wang, Zonghua; Zhang, Feifei; Xia, Jianfei; Yang, Min; Bi, Sai

2014-12-07

Under the two-photon excitation, upconversion luminescent "INHIBIT" and "OR" logic gates of water-dispersed CdTe quantum dots (QDs) were constituted by conjugating the QDs with dopamine. This facilitated the development of a novel QDs-based upconversion luminescent probe for efficient turn-on sensing of glutathione.

Sensitization of nano-porous ZnO photo-anode by a conjugated conducting polymer

Energy Technology Data Exchange (ETDEWEB)

Sirimanne, P.M. [Nano-Science Laboratory, Institute of Fundamental Studies, Hantana Road, Kandy (Sri Lanka); Environmental and Renewable Energy Systems Division, Graduate School of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193 (Japan); Premalal, E.V.A. [Nano-Science Laboratory, Institute of Fundamental Studies, Hantana Road, Kandy (Sri Lanka); Minoura, H. [Environmental and Renewable Energy Systems Division, Graduate School of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193 (Japan)

2011-01-15

Hybrid ZnO films are prepared via one-step electrochemical process. Extraction of organic component from hybrid films results tiny wires like ZnO columns perpendicular to the substrate. Visible light sensitive-conjugated polymer poly(2-methoxy-5-[2 ethylhexyloxy]-1-4-phenylenevinylene, MEH-PPV) was embedded in highly porous ZnO ceramic by a solvent vaporization technique. An attempt was made to fabricate polymer sensitized photovoltaic cell by coupling polymer embedded ZnO electrodes with an electrolyte. Maximum photovoltage of 490 mV is observed for the cell with the configuration of ZnO vertical stroke MEH-PPV vertical stroke I{sup -}/I{sub 3}{sup -} cell. (author)

Opto-electronics of PbS quantum dot and narrow bandgap polymer blends

NARCIS (Netherlands)

Kahmann, Simon; Mura, Andrea; Protesescu, Loredana; Kovalenko, Maksym V.; Brabec, Christoph J.; Loi, Maria A.

2015-01-01

Here we report on the interaction between the narrow bandgap polymer [2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta-[2,1-b;3,4-b]dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) and lead sulphide (PbS) colloidal quantum dots (CQDs) upon photoexcitation. We show that the presence of both materials

Carrier Transport Enhancement in Conjugated Polymers through Interfacial Self-Assembly of Solution-State Aggregates

KAUST Repository

Zhao, Kui

2016-07-13

We demonstrate that local and long range orders of poly(3-hexylthiophene) (P3HT) semicrystalline films can be synergistically improved by combining chemical functionalization of the dielectric surface with solution-state disentanglement and pre-aggregation of P3HT in a theta solvent, leading to a very significant enhancement of the field effect carrier mobility. The pre-aggregation and surface functionalization effects combine to enhance the carrier mobility nearly 100-fold as compared with standard film preparation by spin-coating, and nearly 10-fold increase over the benefits of pre-aggregation alone. In situ quartz crystal microbalance with dissipation (QCM-D) experiments reveal enhanced deposition of pre-aggregates on surfaces modified with an alkyl-terminated self-assembled monolayer (SAM) in comparison to un-aggregated polymer chains. Additional investigations reveal the combined pre-aggregation and surface functionalization significantly enhances local order of the conjugated polymer through planarization and extension of the conjugated backbone of the polymer which clearly translate to significant improvements of carrier transport at the semiconductor-dielectric interface in organic thin film transistors. This study points to opportunities in combining complementary routes, such as well-known pre-aggregation with substrate chemical functionalization, to enhance the polymer self-assembly and improve its interfacial order with benefits for transport properties.

Comparative study of polymer and liquid electrolytes in quantum dot sensitized solar cells

Science.gov (United States)

Poudyal, Uma; Wang, Wenyong

We present the study of CdS/CdSe quantum dot sensitized solar cells (QDSSCs) in which Zn2SnO4\\ nanowires on the conductive glass are used as photoanode. The CdS/CdSe quantum dots (QDs) are deposited in the Zn2SnO4 photoanode by the Successive Ionic Layer Adsorption and Reaction (SILAR) method. CdS is first deposited on the nanowires after which it is further coated with 5 cycles of CdSe QDs. Finally, ZnS is coated on the QDs as a passivation layer. The QD sensitized photoanode are then used to assemble a solar device with the polymer and liquid electrolytes. The Incident Photon to Current Efficiency (IPCE) spectra are obtained for the CdS/CdSe coated nanowires. Further, a stability test of these devices is performed, using the polymer and liquid electrolytes, which provides insight to determine the better working electrolyte in the CdS/CdSe QDSSCs. Department of Energy.

Understanding Interfacial Alignment in Solution Coated Conjugated Polymer Thin Films

International Nuclear Information System (INIS)

Qu, Ge; Zhao, Xikang; Newbloom, Gregory M.; Zhang, Fengjiao; Mohammadi, Erfan

2017-01-01

Domain alignment in conjugated polymer thin films can significantly enhance charge carrier mobility. However, the alignment mechanism during meniscus-guided solution coating remains unclear. Furthermore, interfacial alignment has been rarely studied despite its direct relevance and critical importance to charge transport. In this study, we uncover a significantly higher degree of alignment at the top interface of solution coated thin films, using a donor–acceptor conjugated polymer, poly(diketopyrrolopyrrole-co-thiopheneco- thieno[3,2-b]thiophene-co-thiophene) (DPP2T-TT), as the model system. At the molecular level, we observe in-plane π–π stacking anisotropy of up to 4.8 near the top interface with the polymer backbone aligned parallel to the coating direction. The bulk of the film is only weakly aligned with the backbone oriented transverse to coating. At the mesoscale, we observe a well-defined fibril-like morphology at the top interface with the fibril long axis pointing toward the coating direction. Significantly smaller fibrils with poor orientational order are found on the bottom interface, weakly aligned orthogonal to the fibrils on the top interface. The high degree of alignment at the top interface leads to a charge transport anisotropy of up to 5.4 compared to an anisotropy close to 1 on the bottom interface. We attribute the formation of distinct interfacial morphology to the skin-layer formation associated with high Peclet number, which promotes crystallization on the top interface while suppressing it in the bulk. As a result, we further infer that the interfacial fibril alignment is driven by the extensional flow on the top interface arisen from increasing solvent evaporation rate closer to the meniscus front.

Ambipolar Organic Phototransistors with p-Type/n-Type Conjugated Polymer Bulk Heterojunction Light-Sensing Layers

KAUST Repository

Nam, Sungho; Han, Hyemi; Seo, Jooyeok; Song, Myeonghun; Kim, Hwajeong; Anthopoulos, Thomas D.; McCulloch, Iain; Bradley, Donal D C; Kim, Youngkyoo

2016-01-01

Ambipolar organic phototransistors with sensing channel layers, featuring p-type and n-type conjugated polymer bulk heterojunctions, exhibit outstanding light-sensing characteristics in both p-channel and n-channel sensing operation modes.

Ambipolar Organic Phototransistors with p-Type/n-Type Conjugated Polymer Bulk Heterojunction Light-Sensing Layers

KAUST Repository

Nam, Sungho

2016-11-18

Ambipolar organic phototransistors with sensing channel layers, featuring p-type and n-type conjugated polymer bulk heterojunctions, exhibit outstanding light-sensing characteristics in both p-channel and n-channel sensing operation modes.

Design of porphyrin-based conjugated microporous polymers with enhanced singlet oxygen productivity

Czech Academy of Sciences Publication Activity Database

Hynek, Jan; Rathouský, Jiří; Demel, Jan; Lang, Kamil

2016-01-01

Roč. 6, č. 50 (2016), s. 44279-44287 ISSN 2046-2069 R&D Projects: GA ČR(CZ) GA16-15020S Institutional support: RVO:61388980 ; RVO:61388955 Keywords : Conjugated microporous polymers * Crystalline materials * Metal organic framework * biomimetic catalysis Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) Impact factor: 3.108, year: 2016

In-situ fabrication of diketopyrrolopyrrole-carbazole-based conjugated polymer/TiO2 heterojunction for enhanced visible light photocatalysis

Science.gov (United States)

Yang, Long; Yu, Yuyan; Zhang, Jianling; Chen, Fu; Meng, Xiao; Qiu, Yong; Dan, Yi; Jiang, Long

2018-03-01

Aiming at developing highly efficient photocatalysts by broadening the light-harvesting region and suppressing photo-generated electron-hole recombination simultaneously, this work reports rational design and fabrication of donor-acceptor (D-A) conjugated polymer/TiO2 heterojunction catalyst with strong interfacial interactions by a facile in-situ thermal treatment. To expand the light-harvesting window, soluable conjugated copolymers with D-A architecture are prepared by Pd-mediated polycondensation of diketopyrrolopyrrole (DPP) and t-butoxycarbonyl (t-Boc) modified carbazole (Car), and used as visible-light-harvesting antenna to couple with TiO2 nanocrystals. The DPP-Car/TiO2 composites show wide range absorption in 300-1000 nm. To improve the interfacial binding at the interface, a facile in-situ thermal treatment is carried out to cleave the pendant t-Boc groups in carbazole units and liberate the polar amino groups (-NH-) which strongly bind to the surface of TiO2 through dipole-dipole interactions, forming a heterojunction interface. This in-situ thermal treatment changes the surface elemental distribution of TiO2, reinforces the interface bonding at the boundary of conjugated polymers/TiO2 and finally improves the photocatalytic efficiency of DPP-Car/TiO2 under visible-light irradiation. The interface changes are characterized and verified through Fourier-transform infrared spectroscopy (FT-IR), photo images, UV/Vis (solution state and powder diffuse reflection spectroscopy), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), fluorescence, scanning electron microscopy(SEM) and transmission electron microscopy (TEM) techniques. This study provides a new strategy to avoid the low solubility of D-A conjugated polymers and construct highly-efficient conjugated polymer/TiO2 heterojunction by enforcing the interface contact and facilitating charge or energy transfer for the applications in photocatalysis.

Alkylated indacenodithieno[3,2-b]thiophene-based all donor ladder-type conjugated polymers for organic thin film transistors

KAUST Repository

Lu, Rimei

2018-01-29

We report the synthesis of a series of indacenodithieno[3,2-b]thiophene (IDTT) based conjugated polymers by copolymerization with three different electron rich co-monomers [thiophene (T), thieno[3,2-b]thiophene (TT) and dithieno[3,2-b:2\\',3\\'-d]thiophene (DTT)] under Stille coupling conditions. The resulting all-donor polymers show very good solubility in common solvents and exhibit similar optical, thermal and electronic properties. However, the performance of these semiconductors in thin film transistor devices varied and was highly dependent on the nature of the co-monomer. All polymers exhibited unipolar p-type charge transport behaviour, with the mobility values following the trend of IDTT-TT>IDTT-DTT>IDTT-T. The peak saturation mobility value of IDTT-TT was extracted to be 1.1 cm2V-1s-1, amongst the highest mobility for all-donor conjugated polymers reported to date.

Biocompatible Polymer/Quantum Dots Hybrid Materials: Current Status and Future Developments

Directory of Open Access Journals (Sweden)

Lei Shen

2011-12-01

Full Text Available Quantum dots (QDs are nanometer-sized semiconductor particles with tunable fluorescent optical property that can be adjusted by their chemical composition, size, or shape. In the past 10 years, they have been demonstrated as a powerful fluorescence tool for biological and biomedical applications, such as diagnostics, biosensing and biolabeling. QDs with high fluorescence quantum yield and optical stability are usually synthesized in organic solvents. In aqueous solution, however, their metallic toxicity, non-dissolubility and photo-luminescence instability prevent the direct utility of QDs in biological media. Polymers are widely used to cover and coat QDs for fabricating biocompatible QDs. Such hybrid materials can provide solubility and robust colloidal and optical stability in water. At the same time, polymers can carry ionic or reactive functional groups for incorporation into the end-use application of QDs, such as receptor targeting and cell attachment. This review provides an overview of the recent development of methods for generating biocompatible polymer/QDs hybrid materials with desirable properties. Polymers with different architectures, such as homo- and co-polymer, hyperbranched polymer, and polymeric nanogel, have been used to anchor and protect QDs. The resulted biocompatible polymer/QDs hybrid materials show successful applications in the fields of bioimaging and biosensing. While considerable progress has been made in the design of biocompatible polymer/QDs materials, the research challenges and future developments in this area should affect the technologies of biomaterials and biosensors and result in even better biocompatible polymer/QDs hybrid materials.

Effects of alkyl chain positioning on conjugated polymer microstructure and field-effect mobilities

KAUST Repository

Schroeder, Bob C.; Nielsen, Christian B.; Westacott, Paul; Smith, Jeremy; Rossbauer, Stephan; Anthopoulos, Thomas D.; Stingelin, Natalie; McCulloch, Iain

2015-01-01

Solubilizing alkyl chains play a crucial role in the design of semiconducting polymers because they define the materials solubility and processability as well as both the crystallinity and solid-state microstructure. In this paper, we present a scarcely explored design approach by attaching the alkyl side chains on one side (cis-) or on both sides (trans-) of the conjugated backbone. We further investigate the effects of this structural modification on the solid-state properties of the polymers and on the charge-carrier mobilities in organic thin-film transistors. Copyright © Materials Research Society 2015

Effects of alkyl chain positioning on conjugated polymer microstructure and field-effect mobilities

KAUST Repository

Schroeder, Bob C.

2015-07-02

Solubilizing alkyl chains play a crucial role in the design of semiconducting polymers because they define the materials solubility and processability as well as both the crystallinity and solid-state microstructure. In this paper, we present a scarcely explored design approach by attaching the alkyl side chains on one side (cis-) or on both sides (trans-) of the conjugated backbone. We further investigate the effects of this structural modification on the solid-state properties of the polymers and on the charge-carrier mobilities in organic thin-film transistors. Copyright © Materials Research Society 2015

Comparison of selenophene and thienothiophene incorporation into pentacyclic lactam-based conjugated polymers for organic solar cells

KAUST Repository

Kroon, Renee; Melianas, Armantas; Zhuang, Wenliu; Bergqvist, Jonas; Diaz De Zerio Mendaza, Amaia; Steckler, Timothy T.; Yu, Liyang; Bradley, Siobhan J.; Musumeci, Chiara; Gedefaw, Desta; Nann, Thomas; Amassian, Aram; Mü ller, Christian; Inganä s, Olle; Andersson, Mats R.

2015-01-01

In this work, we compare the effect of incorporating selenophene versus thienothiophene spacers into pentacyclic lactam-based conjugated polymers for organic solar cells. The two cyclic lactam-based copolymers were obtained via a new synthetic method for the lactam moiety. Selenophene incorporation results in a broader and red-shifted optical absorption while retaining a deep highest occupied molecular orbital level, whereas thienothienophene incorporation results in a blue-shifted optical absorption. Additionally, grazing-incidence wide angle X-ray scattering data indicates edge- and face-on solid state order for the selenophene-based polymer as compared to the thienothiophene-based polymer, which orders predominantly edge-on with respect to the substrate. In polymer:PCBM bulk heterojunction solar cells both materials show a similar open-circuit voltage of ∼0.80-0.84 V, however the selenophene-based polymer displays a higher fill factor of ∼0.70 vs. ∼0.65. This is due to the partial face-on backbone orientation of the selenophene-based polymer, leading to a higher hole mobility, as confirmed by single-carrier diode measurements, and a concomitantly higher fill factor. Combined with improved spectral coverage of the selenophene-based polymer, as confirmed by quantum efficiency experiments, it offers a larger short-circuit current density of ∼12 mA cm. Despite the relatively low molecular weight of both materials, a very robust power conversion efficiency ∼7% is achieved for the selenophene-based polymer, while the thienothiophene-based polymer demonstrates only a moderate maximum PCE of ∼5.5%. Hence, the favorable effects of selenophene incorporation on the photovoltaic performance of pentacyclic lactam-based conjugated polymers are clearly demonstrated.

Comparison of selenophene and thienothiophene incorporation into pentacyclic lactam-based conjugated polymers for organic solar cells

KAUST Repository

Kroon, Renee

2015-09-08

In this work, we compare the effect of incorporating selenophene versus thienothiophene spacers into pentacyclic lactam-based conjugated polymers for organic solar cells. The two cyclic lactam-based copolymers were obtained via a new synthetic method for the lactam moiety. Selenophene incorporation results in a broader and red-shifted optical absorption while retaining a deep highest occupied molecular orbital level, whereas thienothienophene incorporation results in a blue-shifted optical absorption. Additionally, grazing-incidence wide angle X-ray scattering data indicates edge- and face-on solid state order for the selenophene-based polymer as compared to the thienothiophene-based polymer, which orders predominantly edge-on with respect to the substrate. In polymer:PCBM bulk heterojunction solar cells both materials show a similar open-circuit voltage of ∼0.80-0.84 V, however the selenophene-based polymer displays a higher fill factor of ∼0.70 vs. ∼0.65. This is due to the partial face-on backbone orientation of the selenophene-based polymer, leading to a higher hole mobility, as confirmed by single-carrier diode measurements, and a concomitantly higher fill factor. Combined with improved spectral coverage of the selenophene-based polymer, as confirmed by quantum efficiency experiments, it offers a larger short-circuit current density of ∼12 mA cm. Despite the relatively low molecular weight of both materials, a very robust power conversion efficiency ∼7% is achieved for the selenophene-based polymer, while the thienothiophene-based polymer demonstrates only a moderate maximum PCE of ∼5.5%. Hence, the favorable effects of selenophene incorporation on the photovoltaic performance of pentacyclic lactam-based conjugated polymers are clearly demonstrated.

Surface chemistry of photoluminescent F8BT conjugated polymer nanoparticles determines protein corona formation and internalization by phagocytic cells.

Science.gov (United States)

Ahmad Khanbeigi, Raha; Abelha, Thais Fedatto; Woods, Arcadia; Rastoin, Olivia; Harvey, Richard D; Jones, Marie-Christine; Forbes, Ben; Green, Mark A; Collins, Helen; Dailey, Lea Ann

2015-03-09

Conjugated polymer nanoparticles are being developed for a variety of diagnostic and theranostic applications. The conjugated polymer, F8BT, a polyfluorene derivative, was used as a model system to examine the biological behavior of conjugated polymer nanoparticle formulations stabilized with ionic (sodium dodecyl sulfate; F8BT-SDS; ∼207 nm; -31 mV) and nonionic (pegylated 12-hydroxystearate; F8BT-PEG; ∼175 nm; -5 mV) surfactants, and compared with polystyrene nanoparticles of a similar size (PS200; ∼217 nm; -40 mV). F8BT nanoparticles were as hydrophobic as PS200 (hydrophobic interaction chromatography index value: 0.96) and showed evidence of protein corona formation after incubation with serum-containing medium; however, unlike polystyrene, F8BT nanoparticles did not enrich specific proteins onto the nanoparticle surface. J774A.1 macrophage cells internalized approximately ∼20% and ∼60% of the F8BT-SDS and PS200 delivered dose (calculated by the ISDD model) in serum-supplemented and serum-free conditions, respectively, while cell association of F8BT-PEG was minimal (<5% of the delivered dose). F8BT-PEG, however, was more cytotoxic (IC50 4.5 μg cm(-2)) than F8BT-SDS or PS200. The study results highlight that F8BT surface chemistry influences the composition of the protein corona, while the properties of the conjugated polymer nanoparticle surfactant stabilizer used determine particle internalization and biocompatibility profile.

Glycidyl methacrylate-co-N-vinyl-2-pyrrolidone coated polypropylene strips: Synthesis, characterization and standardization for dot-enzyme linked immunosorbent assay

Energy Technology Data Exchange (ETDEWEB)

Tyagi, Charu; Tomar, Lomas [Centre for Biomedical Engineering, Indian Institute of Technology, Delhi 110016 (India); Singh, Harpal [Centre for Biomedical Engineering, Indian Institute of Technology, Delhi 110016 (India)], E-mail: tyagicharu11@rediffmail.com

2009-01-26

Glycidyl methacrylate and N-vinyl-2-pyrrolidone (GMA-co-NVP) copolymers with various GMA:NVP ratios were synthesized by solution polymerization technique in toluene using 2,2'-azobisisobutyronitrile (AIBN) as free radical initiator and dip coated onto polypropylene strips. The copolymer composition in polymeric coatings was confirmed by proton NMR spectroscopy. Various techniques like FTIR, SEM and contact angle were used for surface characterization of the polymer coatings. These polymer coated strips were evaluated and standardized for their application in dot-ELISA in two steps. In first step, specificity, sensitivity and reproducibility of the assay on developed polymer coated strips was evaluated through a model system using rabbit anti-goat IgG, goat anti-rabbit IgG and goat anti-rabbit IgG HRP (horseradish peroxidase)-conjugate. Polymer coating with GMA-NVP mol% ratio of 78:22 was able to detect rabbit anti-goat IgG antibody at a concentration as low as 2 ng mL{sup -1} with 1% BSA as blocking agent using antispecies IgG peroxidase conjugate diluted 1500 times. In the second step, the sensitivity and specificity of the developed system was established with human blood and finally used to identify the source of mosquito blood meal which is an important parameter in epidemiological studies, particularly in determining the role of mosquito in malaria transmission. The time duration of standardized assay with developed polymer coated strips was cut down to one hour compared to the 3-4 h required in usual dot-ELISA.

Polymer-Block-Polypeptides and Polymer-Conjugated Hybrid Materials as Stimuli-Responsive Nanocarriers for Biomedical Applications.

Science.gov (United States)

John, Johnson V; Johnson, Renjith P; Heo, Min Seon; Moon, Byeong Kyu; Byeon, Seong Jin; Kim, Il

2015-01-01

Stimuli-responsive nanocarriers are a class of soft materials that includes natural polymers, synthetic polymers, and polypeptides. Recently, modern synthesis tools such as atom transfer radical polymerization, reversible addition-fragmentation chain transfer polymerization, nitroxide-mediated radical polymerization, ring-opening polymerization of α-amino acid N-carboxyanhydrides, and various "click" chemistry strategies were simultaneously employed for the design and synthesis of nanosized drug delivery vehicles. Importantly, the research focused on the improvement of the nanocarrier targetability and the site-specific, triggered release of therapeutics with high drug loading efficiency and minimal drug leakage during the delivery to specific targets. In this context, nanocarriers responsive to common stimuli such as pH, temperature, redox potential, light, etc. have been widely used for the controlled delivery of therapeutics to pathological sites. Currently, different synthesis and self-assembly strategies improved the drug loading efficacy and targeted delivery of therapeutic agents to the desired site. In particular, polypeptide-containing hybrid materials have been developed for the controlled delivery of therapeutic agents. Therefore, stimuli-sensitive synthetic polypeptide-based materials have been extensively investigated in recent years. This review focuses on recent advances in the development of polymer-block-polypeptides and polymer-conjugated hybrid materials that have been designed and evaluated for various stimuli-responsive drug and gene delivery applications.

Multifunctional adhesive polymers: Preactivated thiolated chitosan-EDTA conjugates.

Science.gov (United States)

Netsomboon, Kesinee; Suchaoin, Wongsakorn; Laffleur, Flavia; Prüfert, Felix; Bernkop-Schnürch, Andreas

2017-02-01

The aim of this study was to synthesis preactivated thiolated chitosan-EDTA (Ch-EDTA-cys-2MNA) conjugates exhibiting in particular high mucoadhesive, cohesive and chelating properties. Thiol groups were coupled with chitosan by carbodiimide reaction and further preactivated by attachment with 2-mercaptonicotinic acid (2MNA) via disulfide bond formation. Determinations of primary amino and sulfhydryl groups were performed by TNBS and Ellman's tests, respectively. Cytotoxicity was screened by resazurin assay in Caco-2 cells. Mucoadhesive properties and bivalent cation binding capacity with Mg 2+ and Ca 2+ in comparison to chitosan-EDTA (Ch-EDTA) and thiolated Ch-EDTA (Ch-EDTA-cys) were evaluated. Determination of 2MNA and total sulfhydryl groups indicated that 80% of thiol groups were preactivated. The results from cytotoxicity studies demonstrated that Ch-EDTA-cys and Ch-EDTA-cys-2MNA were not toxic to the cells at the polymer test concentration of 0.25% (w/v) while cell viability decreased by increasing the concentration of Ch-EDTA. Although EDTA molecule was modified by thiolation and preactivation, approximately 50% of chelating properties of the conjugates were maintained compared to Ch-EDTA. Ch-EDTA-cys-2MNA adhered on freshly excised porcine intestinal mucosa up to 6h while Ch-EDTA adhered for just 1h. According to the combination of mucoadhesive and chelating properties of the conjugates synthesized in this study, Ch-EDTA-cys-2MNA might be useful for various mucosal drug delivery systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Peptide-Conjugated Quantum Dots Act as the Target Marker for Human Pancreatic Carcinoma Cells

Directory of Open Access Journals (Sweden)

Shuang-ling Li

2016-03-01

Full Text Available Background/Aims: In the present study, we describe a novel and straightforward approach to produce a cyclic- arginine-glycine-aspartic (RGD-peptide-conjugated quantum dot (QD probe as an ideal target tumor biomarker. Due to its specific structure, the probe can be used for targeted imaging of pancreatic carcinoma cells. Methods: Pancreatic carcinoma cells were routinely cultured and marked with QD-RGD probe. The QD-RGD probe on the fluorescence-labeled cancer cell was observed by fluorescence microscopy and laser confocal microscopy. Cancer cell viability was detected by MTT assay after culturing with QD-RGD probe. Results: Fluorescence microscopy and laser confocal microscopy displayed that 10nmol/L QD-RGD probe was able to effectively mark pancreatic carcinoma cells. In comparison with organic dyes and fluorescent proteins, the quantum dot-RGD probe had unique optical and electronic properties. Conclusion: QD-RGD probe has a low cytotoxicity with an excellent optical property and biocompatibility. These findings support further evaluation of QD-RGD probes for the early detection of pancreatic cancer.

High performance organic distributed Bragg reflector lasers fabricated by dot matrix holography.

Science.gov (United States)

Wan, Wenqiang; Huang, Wenbin; Pu, Donglin; Qiao, Wen; Ye, Yan; Wei, Guojun; Fang, Zongbao; Zhou, Xiaohong; Chen, Linsen

2015-12-14

We report distributed Bragg reflector (DBR) polymer lasers fabricated using dot matrix holography. Pairs of distributed Bragg reflector mirrors with variable mirror separations are fabricated and a novel energy transfer blend consisting of a blue-emitting conjugated polymer and a red-emitting one is spin-coated onto the patterned substrate to complete the device. Under optical pumping, the device emits sing-mode lasing around 622 nm with a bandwidth of 0.41 nm. The working threshold is as low as 13.5 μJ/cm² (~1.68 kW/cm²) and the measured slope efficiency reaches 5.2%. The distributed feedback (DFB) cavity and the DBR cavity resonate at the same lasing wavelength while the DFB laser shows a much higher threshold. We further show that flexible DBR lasers can be conveniently fabricated through the UV-imprinting technique by using the patterned silica substrate as the mold. Dot matrix holography represents a versatile approach to control the number, the size, the location and the orientation of DBR mirrors, thus providing great flexibility in designing DBR lasers.

Synthesis and functions of well-defined polymer-drug conjugates as efficient nanocarriers for intravesical chemotherapy of bladder cancer(a).

Science.gov (United States)

Yu, Qingsong; Zhang, Jiajing; Zhang, Guan; Gan, Zhihua

2015-04-01

Novel poly(ethylene glycol) and poly(N-(2-hydroxypropyl)methacrylamide) block copolymer (PEG-b-PHPMA) with well-defined composition was synthesized by RAFT polymerization. Folate and doxorubicin (DOX) were quantitatively introduced into the copolymer. The influences of folate content and pH value on folate receptor (FR) mediated cell endocytosis and pH-responsive DOX release were studied. It has been demonstrated that minimum folate content is needed for the enrichment of hydrophobic folate on the hydrophilic part of polymer conjugates. The cytotoxicity of targetable polymer drug conjugates was much higher than that of non-targetable ones and free DOX. It could be concluded that the folate plays a significant role in targeting and internalization of the conjugates against bladder cancer cells. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Real-time observation of conformational switching in single conjugated polymer chains.

Science.gov (United States)

Tenopala-Carmona, Francisco; Fronk, Stephanie; Bazan, Guillermo C; Samuel, Ifor D W; Penedo, J Carlos

2018-02-01

Conjugated polymers (CPs) are an important class of organic semiconductors that combine novel optoelectronic properties with simple processing from organic solvents. It is important to study CP conformation in solution to understand the physics of these materials and because it affects the properties of solution-processed films. Single-molecule techniques are unique in their ability to extract information on a chain-to-chain basis; however, in the context of CPs, technical challenges have limited their general application to host matrices or semiliquid environments that constrain the conformational dynamics of the polymer. We introduce a conceptually different methodology that enables measurements in organic solvents using the single-end anchoring of polymer chains to avoid diffusion while preserving polymer flexibility. We explore the effect of organic solvents and show that, in addition to chain-to-chain conformational heterogeneity, collapsed and extended polymer segments can coexist within the same chain. The technique enables real-time solvent-exchange measurements, which show that anchored CP chains respond to sudden changes in solvent conditions on a subsecond time scale. Our results give an unprecedented glimpse into the mechanism of solvent-induced reorganization of CPs and can be expected to lead to a new range of techniques to investigate and conformationally manipulate CPs.

Polythiophenes Comprising Conjugated Pendants for Polymer Solar Cells: A Review

Directory of Open Access Journals (Sweden)

Hsing-Ju Wang

2014-03-01

Full Text Available Polythiophene (PT is one of the widely used donor materials for solution-processable polymer solar cells (PSCs. Much progress in PT-based PSCs can be attributed to the design of novel PTs exhibiting intense and broad visible absorption with high charge carrier mobility to increase short-circuit current density (Jsc, along with low-lying highest occupied molecular orbital (HOMO levels to achieve large open circuit voltage (Voc values. A promising strategy to tailor the photophysical properties and energy levels via covalently attaching electron donor and acceptor pendants on PTs backbone has attracted much attention recently. The geometry, electron-donating capacity, and composition of conjugated pendants are supposed to be the crucial factors in adjusting the conformation, energy levels, and photovoltaic performance of PTs. This review will go over the most recent approaches that enable researchers to obtain in-depth information in the development of PTs comprising conjugated pendants for PSCs.

Developments in the chemistry and band gap engineering of donor-acceptor substituted conjugated polymers

NARCIS (Netherlands)

Mullekom, van H.A.M.; Vekemans, J.A.J.M.; Havinga, E.E.; Meijer, E.W.

2001-01-01

This paper reviews the tools to manipulate and minimize the band gap of conjugated (co)polymers. The effects of minimization of the bond length alternation and of the incorporation of donor-K-acceptor units are discussed in particular. A systematic study of a series of alternating donor-acceptor

Photochemical stability of conjugated polymers, electron acceptors and blends for polymer solar cells resolved in terms of film thickness and absorbance

DEFF Research Database (Denmark)

Tromholt, Thomas; Vesterager Madsen, Morten; Carlé, Jon Eggert

2012-01-01

Photochemical degradation at 1 sun under AM1.5G illumination was performed on six conjugated polymers and five different electron acceptors. Additionally, the respective polymer:PC60BM and P3HT:electron acceptor blends were studied, and all degradations were resolved in terms of film thickness...... within each material group were found to vary for both the pure polymers and the blends. The stability ranking between the materials of the pure polymers was found to be similar to the ranking for their respective blends, implying that the photochemical stability of a pure polymer is a good measure...... of its associated blend stability. Different electron acceptors were found to stabilize P3HT decreasingly with decreasing donor–acceptor LUMO–LUMO gap. Destabilization of P3HT was observed in the case of the electron acceptor ICBA. Additionally, the decreased stabilization of P3HT by high LUMO electron...

Water-mediated green synthesis of PbS quantum dot and its glutathione and biotin conjugates for non-invasive live cell imaging

Science.gov (United States)

Vijaya Bharathi, M.; Maiti, Santanu; Sarkar, Bidisha; Ghosh, Kaustab; Paira, Priyankar

2018-03-01

This study addresses the cellular uptake of nanomaterials in the field of bio-applications. In the present study, we have synthesized water-soluble lead sulfide quantum dot (PbS QD) with glutathione and 3-MPA (mercaptopropionic acid) as the stabilizing ligand using a green approach. 3-MPA-capped QDs were further modified with streptavidin and then bound to biotin because of its high conjugation efficiency. Labelling and bio-imaging of cells with these bio-conjugated QDs were evaluated. The bright red fluorescence from these types of QDs in HeLa cells makes these materials suitable for deep tissue imaging.

Charge transport in conjugated polymers: a multiscale picture

Science.gov (United States)

Ruehle, Victor; Kirkpatrick, James; Kremer, Kurt; Andrienko, Denis

2009-03-01

A framework to study charge transport in conjugated polymers using realistic morphologies is developed. First, the atomistic force field is refined using first-principles calculations. Systematic coarse graining is then performed to extend simulation times and system sizes accessible to molecular dynamics simulations. Material morphologies are generated using the coarse grained and atomistic models. Finally, the charge mobility is obtained using temperature activated hopping picture for charge transport [1]. The framework is tested on neutral and oxidized polypyrrole with different structural ordering [2]. [4pt] [1] J. Kirkpatrick, V. Marcon, J. Nelson, K. Kremer, D. Andrienko, Phys. Rev. Lett. 98, 227402 (2007)[0pt] [2] V. Ruehle, J. Kirkpatrick, K. Kremer, D. Andrienko, Phys. Stat. Solidi B, 245, 844 (2008)

Stiffness, strength and adhesion characterization of electrochemically deposited conjugated polymer films

Science.gov (United States)

Qu, Jing; Ouyang, Liangqi; Kuo, Chin-chen; Martin, David C.

2015-01-01

Conjugated polymers such as poly(3,4-ethylenedioxythiphene) (PEDOT) are of interest for a variety of applications including interfaces between electronic biomedical devices and living tissue. The mechanical properties, strength, and adhesion of these materials to solid substrates are all vital for long-term applications. We have been developing methods to quantify the mechanical properties of conjugated polymer thin films. In this study the stiffness, strength and the interfacial shear strength (adhesion) of electrochemically deposited PEDOT and PEDOT-co-1,3,5-tri[2-(3,4-ethylene dioxythienyl)]-benzene (EPh) were studied. The estimated Young’s modulus of the PEDOT films was 2.6 ± 1.4 GPa, and the strain to failure was around 2%. The tensile strength was measured to be 56 ± 27 MPa. The effective interfacial shear strength was estimated with a shear-lag model by measuring the crack spacing as a function of film thickness. For PEDOT on gold/palladium-coated hydrocarbon film substrates an interfacial shear strength of 0.7 ± 0.3 MPa was determined. The addition of 5 mole% of a tri-functional EDOT crosslinker (EPh) increased the tensile strength of the films to 283 ± 67 MPa, while the strain to failure remained about the same (2%). The effective interfacial shear strength was increased to 2.4 ± 0.6 MPa. PMID:26607768

Electroactive subwavelength gratings (ESWGs) from conjugated polymers for color and intensity modulation

Science.gov (United States)

Bhuvana, Thiruvelu; Kim, Byeonggwan; Yang, Xu; Shin, Haijin; Kim, Eunkyoung

2012-05-01

Subwavelength gratings with electroactive polymers such as poly(3-hexylthiophene) (P3HT) and poly(3,4-propylenedioxythiophene-phenylene) (P(ProDOT-Ph)) controlled the color intensity for various visible colors of diffracted light in a single device. Under the illumination of a white light, at a fixed angle of incidence, the color intensity of the diffracted light was reversibly switched from the maximum value down to 15% (85% decrease) by applying -2 to 2 V due to electrochemical (EC) reaction. All spectral colors including red, green, and blue were generated by changing the angle of incidence, and the intensity of each color was modulated electrochemically at a single EC device. With electroactive subwavelength gratings (ESWGs) of P3HT, the maximum modulation of the color intensity was observed in the red-yellow quadrant in the CIE color plot, whereas for the ESWGs of P(ProDOT-Ph), the maximum modulation of the color intensity was observed in the yellow-green and green-blue quadrants. Both ESWGs showed a memory effect, keeping their color and intensity even after power was turned off for longer than 40 hours.Subwavelength gratings with electroactive polymers such as poly(3-hexylthiophene) (P3HT) and poly(3,4-propylenedioxythiophene-phenylene) (P(ProDOT-Ph)) controlled the color intensity for various visible colors of diffracted light in a single device. Under the illumination of a white light, at a fixed angle of incidence, the color intensity of the diffracted light was reversibly switched from the maximum value down to 15% (85% decrease) by applying -2 to 2 V due to electrochemical (EC) reaction. All spectral colors including red, green, and blue were generated by changing the angle of incidence, and the intensity of each color was modulated electrochemically at a single EC device. With electroactive subwavelength gratings (ESWGs) of P3HT, the maximum modulation of the color intensity was observed in the red-yellow quadrant in the CIE color plot, whereas for the

Time Evolution of the Excimer State of a Conjugated Polymer Laser

Directory of Open Access Journals (Sweden)

Wafa Musa Mujamammi

2017-11-01

Full Text Available An excited dimer is an important complex formed in nano- or pico-second time scales in many photophysics and photochemistry applications. The spectral and temporal profile of the excimer state of a laser from a new conjugated polymer, namely, poly (9,9-dioctylfluorenyl-2,7-diyl (PFO, under several concentrations in benzene were investigated. These solutions were optically pumped by intense pulsed third-harmonic Nd:YAG laser (355-nm to obtain the amplified spontaneous emission (ASE spectra of a monomer and an excimer with bandwidths of 6 and 7 nm, respectively. The monomer and excimer ASEs were dependent on the PFO concentration, pump power, and temperature. Employing a sophisticated picosecond spectrometer, the time evolution of the excimer state of this polymer, which is over 400 ps, can be monitored.

Star polymer-drug conjugates with pH-controlled drug release and carrier degradation

Czech Academy of Sciences Publication Activity Database

Kostková, Hana; Schindler, Lucie; Kotrchová, Lenka; Kovář, Marek; Šírová, Milada; Kostka, Libor; Etrych, Tomáš

2017-01-01

Roč. 2017, 3 January (2017), s. 1-10, č. článku 8675435. ISSN 1687-4110 R&D Projects: GA MŠk(CZ) LQ1604 Institutional support: RVO:61389013 ; RVO:61388971 Keywords : star conjugate * HPMA copolymer * doxorubicin Subject RIV: CD - Macromolecular Chemistry; EE - Microbiology, Virology (MBU-M) OBOR OECD: Polymer science; Microbiology (MBU-M) Impact factor: 1.871, year: 2016

Charge transport behavior of benodithiophene-diketopyrrololpyrrole-based conjugated polymer in organic field-effect transistors

Energy Technology Data Exchange (ETDEWEB)

Park, Jin Kuen [Dept. of Chemistry, Hankuk University of Foreign Studies, Yongin (Korea, Republic of)

2015-07-15

Organic optoelectronic devices, such as light-emitting diodes, organic solar cells (OSCs), and organic field effect transistors (OFETs), have emerged due to the development of π-conjugated polymers. Because the delocalized π-framework can significantly reduce the energy gap between the highest-occupied molecular orbital (HOMO) and the lowest-unoccupied molecular orbital (LUMO), their intrinsic optoelectronic properties can be tunable with their conjugation length in terms of average molecular weights and their π-backbone structures. The new type of low bandgap conjugated polymer (P1) has been successively polymerized via a palladium- catalyzed Stille cross-coupling reaction with bis-ethylhexyl BDT and bis-n-decane DPP. With a linear alkyl chain in the DPP units, the intermolecular packing structure was thought to be enhanced by proving the UV–Vis and UPS spectra. In addition, the electronic properties of P1 via field-effect transistors well illustrate the typical p-type semiconducting property without showing the significant improvement by thermal annealing. From a broader perspective, this research indicates that a wider choice of linear alkyl chain length in DPP units and modification of the interface between dielectric and active layers should be sought to further optimize device performance. Hence, progressive works with the strategy presented in this report will be pursued to address the different challenges in attaining target OFET performances.

Quantum dot bio-conjugate: as a western blot probe for highly sensitive detection of cellular proteins

Energy Technology Data Exchange (ETDEWEB)

Kale, Sonia [Agharkar Research Institute (India); Kale, Anup [University of Alabama, Center for Materials for Information Technology (United States); Gholap, Haribhau; Rana, Abhimanyu [National Chemical Laboratory, Physical and Materials Chemistry Division (India); Desai, Rama [National Centre for Cell Science (India); Banpurkar, Arun [University of Pune, Department of Physics (India); Ogale, Satishchandra, E-mail: sb.ogale@ncl.res.in [National Chemical Laboratory, Physical and Materials Chemistry Division (India); Shastry, Padma, E-mail: padma@nccs.res.in [National Centre for Cell Science (India)

2012-03-15

In the present study, we report a quantum dot (QD)-tailored western blot analysis for a sensitive, rapid and flexible detection of the nuclear and cytoplasmic proteins. Highly luminescent CdTe and (CdTe)ZnS QDs are synthesized by aqueous method. High resolution transmission electron microscopy, Raman spectroscopy, fourier transform infrared spectroscopy, fluorescence spectroscopy and X-ray diffraction are used to characterize the properties of the quantum dots. The QDs are functionalized with antibodies of prostate apoptosis response-4 (Par-4), poly(ADP-ribose) polymerases and {beta} actin to specifically bind with the proteins localized in the nucleus and cytoplasm of the cells, respectively. The QD-conjugated antibodies are used to overcome the limitations of conventional western blot technique. The sensitivity and rapidity of protein detection in QD-based approach is very high, with detection limits up to 10 pg of protein. In addition, these labels provide the capability of enhanced identification and localization of marker proteins in intact cells by confocal laser scanning microscopy.

AMP-Conjugated Quantum Dots: Low Immunotoxicity Both In Vitro and In Vivo

Science.gov (United States)

Dai, Tongcheng; Li, Na; Liu, Lu; Liu, Qin; Zhang, Yuanxing

2015-11-01

Quantum dots (QDs) are engineered nanoparticles that possess special optical and electronic properties and have shown great promise for future biomedical applications. In this work, adenosine 5'-monophosphate (AMP), a small biocompatible molecular, was conjugated to organic QDs to produce hydrophilic AMP-QDs. Using macrophage J774A.1 as the cell model, AMP-QDs exhibited both prior imaging property and low toxicity, and more importantly, triggered limited innate immune responses in macrophage, indicating low immunotoxicity in vitro. Using BALB/c mice as the animal model, AMP-QDs were found to be detained in immune organs but did not evoke robust inflammation responses or obvious histopathological abnormalities, which reveals low immunotoxicity in vivo. This work suggests that AMP is an excellent surface ligand with low immunotoxicity, and potentially used in surface modification for more extensive nanoparticles.

Analytical nanosphere sensors using quantum dot-enzyme conjugates for urea and creatinine.

Science.gov (United States)

Ruedas-Rama, Maria J; Hall, Elizabeth A H

2010-11-01

An enzyme-linked analytical nanosphere sensor (ANSor) is described, responding to enzyme-substrate turnover in the vicinity of a quantum dot (QD) due to coimmobilized enzyme and pH sensitive ligand. QD capping by mercapto-alkanoic acids were rejected as a pH sensitive ligand, but with the use of a layer-by-layer assembly on mercaptopropionic capped QDs and an intermediate poly(allylamine hydrochloride) layer, anthraquinone sulfonate (calcium red, CaR) was introduced to modify the pKa in the immobilized system > 8. QD-CaR absorption shows spectral overlap with QD530 emission at all pHs and gives a complex pH dependent fluorescence resonance energy transfer (FRET) efficiency, due to excited state proton transfer (λ(ex) = 540 nm; λ(em) = 585 nm). In contrast QD615-CaR with spectral overlap between the QD and CaR gave a strong and reproducible pH response. QD-urease and QD-creatinine deiminase conjugates could be linked with pH changes produced by enzyme degradation of urea and creatinine, respectively. Close coupling between the pH sensitive QD and enzyme conjugate maximized signal compared with solution based assays: QD-urease and QD-CD bioconjugates were tested in model biological media (Dulbecco's modified Eagle's Medium and fetal calf serum) and in urine, showing a response in 3-4 min.

Effect of interchain coupling on the excited polaron in conjugated polymers

International Nuclear Information System (INIS)

Li, Xiao-xue; Chen, Gang

2017-01-01

Based on the one-dimensional extended Su–Schrieffer–Heeger model, we theoretically investigate the effect of interchain coupling on the formation and polarization of the single-excited state of polaron in conjugated polymers. It is found that there exists a turnover value of the coupling strength, over which the excited polaron could not be formed in either of the two coupled chains. Instead, a polaron-like particle is localized at the center of each chain. In addition, we also find that the reverse polarization of the excited polaron could be enhanced for some cases in polymer when the interchain coupling becomes strong until it exceeds the critical value. - Highlights: • Effect of interchain coupling on the single-excited state of polaron is studied. • When coupling strength exceeds critical value, the excited polaron is dissociated. • Soliton pair could be dissociated into polaron-like particle with strong coupling. • Reverse polarization of excited polaron is enhanced by weak interchain coupling. • Reverse polarization is obtained more easily in solid film of polymer molecules.

Effect of interchain coupling on the excited polaron in conjugated polymers

Energy Technology Data Exchange (ETDEWEB)

Li, Xiao-xue, E-mail: sps_lixx@ujn.edu.cn; Chen, Gang, E-mail: ss_cheng@ujn.edu.cn

2017-02-05

Based on the one-dimensional extended Su–Schrieffer–Heeger model, we theoretically investigate the effect of interchain coupling on the formation and polarization of the single-excited state of polaron in conjugated polymers. It is found that there exists a turnover value of the coupling strength, over which the excited polaron could not be formed in either of the two coupled chains. Instead, a polaron-like particle is localized at the center of each chain. In addition, we also find that the reverse polarization of the excited polaron could be enhanced for some cases in polymer when the interchain coupling becomes strong until it exceeds the critical value. - Highlights: • Effect of interchain coupling on the single-excited state of polaron is studied. • When coupling strength exceeds critical value, the excited polaron is dissociated. • Soliton pair could be dissociated into polaron-like particle with strong coupling. • Reverse polarization of excited polaron is enhanced by weak interchain coupling. • Reverse polarization is obtained more easily in solid film of polymer molecules.

Hybrid fluorescent nanoparticles fabricated from pyridine-functionalized polyfluorene-based conjugated polymer as reversible pH probes over a broad range of acidity-alkalinity

International Nuclear Information System (INIS)

Cui, Haijun; Chen, Ying; Li, Lianshan; Tang, Zhiyong; Wu, Yishi; Fu, Hongbing; Tian, Zhiyuan

2014-01-01

Conjugated polymer nanoparticles (CPNs) were developed based on a polyfluorene-based conjugated polymer with thiophene units carrying pyridyl moieties incorporated in the backbone of polymer chains (PFPyT). Hybrid CPNs fabricated from PFPyT and an amphiphilic polymer (NP1) displayed pH-sensitive fluorescence emission features in the range from pH 4.8 to 13, which makes them an attractive nanomaterial for wide range optical sensing of pH values. The fluorescence of hybrid CPNs based on chemically close polyfluorene derivatives without pyridyl moieties (NP3), in contrast, remains virtually unperturbed by pH values in the same range. The fluorescence emission features of NP1 underwent fully reversible changes upon alternating acidification/basification of aqueous dispersions of the CPNs and also displayed excellent repeatability. The observed pH sensing properties of NP1 are attributed to protonation/deprotonation of the nitrogen atoms of the pyridine moieties. This, in turn, leads to the redistribution of electron density of pyridine moieties and their participation in the π-conjugation within the polymer main chains. The optically transparent amphiphilic polymers also exerted significant influence on the pH sensing features of the CPNs, likely by acting as proton sponge and/or acid chaperone. (author)

Influence of graphene quantum dots on electrical properties of polymer composites

Science.gov (United States)

Arthisree, D.; Joshi, Girish M.

2017-07-01

We successfully prepared synthetic nanocomposite (SNC) by dispersing graphene quantum dots (GQD) in cellulose acetate (CA) polymer system. The dispersion and occupied network of GQD were foreseen by microscopic techniques. The variation of plane to crossed linked array network was observed by the polarizing optical microscopic (POM) technique. The scanning electron microscopy (SEM) revealed the leaves like impressions of GQD in host polymer system. The series network of GQD occupied in CA at higher resolution was confirmed by transmission electron microscopy (TEM). The two dimensional (2D) topographic images demonstrated an entangled polymer network to plane morphology. The variation in surface roughness was evaluated from the dimensional (3D) topography. The influence of temperature on AC conductivity with highest value (4  ×  10-5 S cm-1), contributes to the decrease in activation energy. The DC conductivity obeys the percolation criteria co-related to the GQD loading by weight fraction. Furthermore, this synthetic nanocomposite is feasible for the development of sensing and electrical applications.

RIR-MAPLE deposition of conjugated polymers and hybrid nanocomposites for application to optoelectronic devices

International Nuclear Information System (INIS)

Stiff-Roberts, Adrienne D.; Pate, Ryan; McCormick, Ryan; Lantz, Kevin R.

2012-01-01

Resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) is a variation of pulsed laser deposition that is useful for organic-based thin films because it reduces material degradation by selective absorption of infrared radiation in the host matrix. A unique emulsion-based RIR-MAPLE approach has been developed that reduces substrate exposure to solvents and provides controlled and repeatable organic thin film deposition. In order to establish emulsion-based RIR-MAPLE as a preferred deposition technique for conjugated polymer or hybrid nanocomposite optoelectronic devices, studies have been conducted to demonstrate the value added by the approach in comparison to traditional solution-based deposition techniques, and this work will be reviewed. The control of hybrid nanocomposite thin film deposition, and the photoconductivity in such materials deposited using emulsion-based RIR-MAPLE, will also be reviewed. The overall result of these studies is the demonstration of emulsion-based RIR-MAPLE as a viable option for the fabrication of conjugated polymer and hybrid nanocomposite optoelectronic devices that could yield improved device performance.

Evaluation of Anti-Inflammatory Drug-Conjugated Silicon Quantum Dots: Their Cytotoxicity and Biological Effect

Directory of Open Access Journals (Sweden)

Kenji Yamamoto

2013-01-01

Full Text Available Silicon quantum dots (Si-QDs have great potential for biomedical applications, including their use as biological fluorescent markers and carriers for drug delivery systems. Biologically inert Si-QDs are less toxic than conventional cadmium-based QDs, and can modify the surface of the Si-QD with covalent bond. We synthesized water-soluble alminoprofen-conjugated Si-QDs (Ap-Si. Alminoprofen is a non-steroid anti-inflammatory drug (NSAID used as an analgesic for rheumatism. Our results showed that the “silicon drug” is less toxic than the control Si-QD and the original drug. These phenomena indicate that the condensed surface integration of ligand/receptor-type drugs might reduce the adverse interaction between the cells and drug molecules. In addition, the medicinal effect of the Si-QDs (i.e., the inhibition of COX-2 enzyme was maintained compared to that of the original drug. The same drug effect is related to the integration ratio of original drugs, which might control the binding interaction between COX-2 and the silicon drug. We conclude that drug conjugation with biocompatible Si-QDs is a potential method for functional pharmaceutical drug development.

Hopping approach towards exciton dissociation in conjugated polymers

International Nuclear Information System (INIS)

Emelianova, E. V.; Auweraer, M. van der; Baessler, H.

2008-01-01

By employing random walk an analytic theory for the dissociation of singlet excitons in a random organic solid, for instance, a conjugated polymer, has been developed. At variance of conventional three-dimensional Onsager theory, it is assumed that an exciton with finite lifetime can first transfer endothermically an electron to an adjacent site, thereby generating a charge transfer state whose energy is above the energy of that of the initial exciton. In a second step the latter can fully dissociate in accordance with Onsager's concept Brownian motion. The results indicate that, depending of the energy required for the first jump, the first jump contributes significantly to the field dependence of the dissociation yield. Disorder weakens the temperature dependence of the yield dramatically and precludes extracting information on the exciton binding energy from it

HPMA copolymer-based polymer conjugates for the delivery and controlled release of retinoids

Czech Academy of Sciences Publication Activity Database

Lidický, Ondřej; Šírová, Milada; Etrych, Tomáš

2016-01-01

Roč. 65, Suppl. 2 (2016), S233-S241 ISSN 0862-8408 R&D Projects: GA MŠk(CZ) LQ1604 Institutional support: RVO:61389013 ; RVO:61388971 Keywords : polymer conjugate * retinoid * HPMA Subject RIV: EB - Genetics ; Molecular Biology; EA - Cell Biology (MBU-M) Impact factor: 1.461, year: 2016 http://www.biomed.cas.cz/physiolres/pdf/65%20Suppl%202/65_S233.pdf

Single-Molecule Luminescence and High Efficiency Photovoltaic Cells Based on Percolated Conducting Carbon Nanotubes Scaffolds Templated with Light-Harvesting Conjugated Polymers and Nanohybrids

National Research Council Canada - National Science Library

Yang, Arnold C

2009-01-01

.... Nanocomposites constructed by surface-grafted multiwall carbon nanotubes (CNTs) with conjugated polymers dispersed in a polymer matrix were synthesized to form novel optoelectronic materials that exploit single-molecule effects...

Effect of side chain length on charge transport, morphology, and photovoltaic performance of conjugated polymers in bulk heterojunction solar cells

NARCIS (Netherlands)

Duan, C.; Willems, R.E.M.; van Franeker, J.J.; Bruijnaers, B.J.; Wienk, M.M.; Janssen, R.A.J.

2016-01-01

The effect of side chain length on the photovoltaic properties of conjugated polymers is systematically investigated with two sets of polymers that bear different alkyl side chain lengths based on benzodithiophene and benzo[2,1,3]thiadiazole or 5,6-difluorobenzo[2,1,3]thiadiazole. Characterization

Development and validation of an in vitro pharmacokinetic/pharmacodynamic model to test the antibacterial efficacy of antibiotic polymer conjugates.

Science.gov (United States)

Azzopardi, Ernest A; Ferguson, Elaine L; Thomas, David W

2015-04-01

This study describes the use of a novel, two-compartment, static dialysis bag model to study the release, diffusion, and antibacterial activity of a novel, bioresponsive dextrin-colistin polymer conjugate against multidrug resistant (MDR) wild-type Acinetobacter baumannii. In this model, colistin sulfate, at its MIC, produced a rapid and extensive drop in viable bacterial counts (growth for up to 48 h, with 3 log10 CFU/ml lower bacterial counts after 48 h than those of controls. Doubling the concentration of dextrin-colistin conjugate (to 2× MIC) led to an initial bacterial killing of 3 log10 CFU/ml at 8 h, with a similar regrowth profile to 1× MIC treatment thereafter. The addition of colistin sulfate (1× MIC) to dextrin-colistin conjugate (1× MIC) resulted in undetectable bacterial counts after 4 h, followed by suppressed bacterial growth (3.5 log10 CFU/ml lower than that of control at 48 h). Incubation of dextrin-colistin conjugates with infected wound exudate from a series of burn patients (n = 6) revealed an increasing concentration of unmasked colistin in the outer compartment (OC) over time (up to 86.3% of the initial dose at 48 h), confirming that colistin would be liberated from the conjugate by endogenous α-amylase within the wound environment. These studies confirm the utility of this model system to simulate the pharmacokinetics of colistin formation in humans administered dextrin-colistin conjugates and further supports the development of antibiotic polymer conjugates in the treatment of MDR infections. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Modelling of charge carrier transport in conjugated polymers doped by polar additives

Czech Academy of Sciences Publication Activity Database

Toman, Petr; Nešpůrek, Stanislav; Bartkowiak, W.

2009-01-01

Roč. 27, č. 3 (2009), s. 797-812 ISSN 0137-1339. [International Conference on Electrical and Related Properties of Organic Solids /11./. Piechowice, 13.07.2008-17.07.2008] R&D Projects: GA ČR GA203/06/0285; GA AV ČR KAN400720701; GA MŠk MEB050815 Institutional research plan: CEZ:AV0Z40500505 Keywords : conjugated polymers * charge carrier transport * molecular electronics Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.384, year: 2009

Microfluidic Fabrication of Conjugated Polymer Sensor Fibers

Energy Technology Data Exchange (ETDEWEB)

Yoo, Imsung; Song, Simon [Hanyang University, Seoul (Korea, Republic of)

2014-10-15

We propose a fabrication method for polydiacetylene (PDA)-embedded hydrogel microfibers on a microfluidic chip. These fibers can be applied to the detection of cyclodextrines (CDs), which are a family of sugar and aluminum ions. PDA, a family of conjugated polymers, has unique characteristics when used for a sensor, because it undergoes a blue-to-red color transition and nonfluorescence-to-fluorescence transition in response to environmental stimulation. PDAs have different sensing characteristics depending on the head group of PCDA. By taking advantage of ionic crosslinking-induced hydrogel formation and the 3D hydrodynamic focusing effect on a microfluidic chip, PCDA-EDEA-derived diacetylene (DA) monomer-embedded microfibers were successfully fabricated. UV irradiation of the fibers afforded blue-colored PDA, and the resulting blue PDA fibers underwent a phase transition to red and emitted red fluorescence upon exposure to CDs and aluminum ions. Their fluorescence intensity varied depending on the CDs and aluminum ion concentrations. This phase transition was also observed when the fibers were dried.

Theory of optical transitions in conjugated polymers. I. Ideal systems.

Science.gov (United States)

Barford, William; Marcus, Max

2014-10-28

We describe a theory of linear optical transitions in conjugated polymers. The theory is based on three assumptions. The first is that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω ≪ J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. Using these assumptions we derive an expression for an effective Huang-Rhys parameter for a chain (or chromophore) of N monomers, given by S(N) = S(1)/IPR, where S(1) is the Huang-Rhys parameter for an isolated monomer. IPR is the inverse participation ratio, defined by IPR = (∑(n)|Ψ(n)|(4))(-1), where Ψ(n) is the exciton center-of-mass wavefunction. Since the IPR is proportional to the spread of the exciton center-of-mass wavefunction, this is a key result, as it shows that S(N) decreases with chain length. As in molecules, in a polymer S(N) has two interpretations. First, ℏωS(N) is the relaxation energy of an excited state caused by its coupling to the normal modes. Second, S(N) appears in the definition of an effective Franck-Condon factor, F(0v)(N) = S(N)(v)exp ( - S(N))/v! for the vth vibronic manifold. We show that the 0 - 0 and 0 - 1 optical intensities are proportional to F00(N) and F01(N), respectively, and thus the ratio of the 0 - 1 to 0 - 0 absorption and emission intensities are proportional to S(N). These analytical results are checked by extensive DMRG calculations and found to be generally valid, particularly for emission. However, for large chain lengths higher-lying quasimomentum exciton states become degenerate with the lowest vibrational excitation of the lowest exciton state. When this happens there is

Transmissive-to-black fast electrochromic switching from a long conjugated pendant group and a highly dispersed polymer/SWNT

KAUST Repository

Zhang, Qiang

2018-01-03

In this study, a novel conjugated polymer, denoted as ECPblack, is synthesized. ECPblack demonstrated a unique electrochromic behavior with an ultrahigh contrast ratio (over 80%) in most of the visible regions, boasting an ultrahigh integrated contrast ratio of 71.8% between 380 nm and 880 nm. The long conjugated pendant group (pyrene) in ECPblack enhances the absorption in the blue region in its second oxidized state and results in transmissive-to-black electrochromic switching between the neutral state and the oxidized state. The transmissive-to-black electrochromic switching polymer with an ultrahigh contrast ratio could be especially attractive for applications in electronic displays. In addition, when polytriarylamine/nanotube (SWNT/P2) dispersion is doped in ECPblack, the response time of its electrochemical and electrochromic behaviors is further reduced. The electrochromic switching and bleaching time of SWNT/P2/ECPblack decreased by 73% and 80%, respectively. The improvement is caused by the phase separation of the rigid SWNT and the flexible polymer, which generates a rough surface morphology and provides more pathways for faster diffusion of counterions (ClO4-). The polymer/SWNT doping technique provides a simple way to accelerate ion diffusion in anodically coloring materials.

Transmissive-to-black fast electrochromic switching from a long conjugated pendant group and a highly dispersed polymer/SWNT

KAUST Repository

Zhang, Qiang; Tsai, Chou-Yi; Abidin, Taufik; Jiang, Jyh-Chiang; Shie, Wan-Ru; Li, Lain-Jong; Liaw, Der-Jang

2018-01-01

In this study, a novel conjugated polymer, denoted as ECPblack, is synthesized. ECPblack demonstrated a unique electrochromic behavior with an ultrahigh contrast ratio (over 80%) in most of the visible regions, boasting an ultrahigh integrated contrast ratio of 71.8% between 380 nm and 880 nm. The long conjugated pendant group (pyrene) in ECPblack enhances the absorption in the blue region in its second oxidized state and results in transmissive-to-black electrochromic switching between the neutral state and the oxidized state. The transmissive-to-black electrochromic switching polymer with an ultrahigh contrast ratio could be especially attractive for applications in electronic displays. In addition, when polytriarylamine/nanotube (SWNT/P2) dispersion is doped in ECPblack, the response time of its electrochemical and electrochromic behaviors is further reduced. The electrochromic switching and bleaching time of SWNT/P2/ECPblack decreased by 73% and 80%, respectively. The improvement is caused by the phase separation of the rigid SWNT and the flexible polymer, which generates a rough surface morphology and provides more pathways for faster diffusion of counterions (ClO4-). The polymer/SWNT doping technique provides a simple way to accelerate ion diffusion in anodically coloring materials.

Fabrication of white light-emitting diodes based on UV light-emitting diodes with conjugated polymers-(CdSe/ZnS) quantum dots as hybrid phosphors.

Science.gov (United States)

Jung, Hyunchul; Chung, Wonkeun; Lee, Chang Hun; Kim, Sung Hyun

2012-07-01

White light-emitting diodes (LEDs) were fabricated using GaN-based 380-nm UV LEDs precoated with the composite of blue-emitting polymer (poly[(9,9-dihexylfluorenyl-2,7-diyl)-alt-co-(2-methoxy-5-{2-ethylhexyloxy)-1 ,4-phenylene)]), yellow green-emitting polymer (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadiazole)]), and 605-nm red-emitting quantum dots (QDs). CdSe cores were obtained by solvothermal route using CdO, Se precursors and ZnS shells were synthesized by using diethylzinc, and hexamethyldisilathiane precursors. The optical properties of CdSe/ZnS QDs were characterized by UV-visible and photoluminescence (PL) spectra. The structural data and composition of the QDs were transmission electron microscopy (TEM), and EDX technique. The quantum yield and size of the QDs were 58.7% and about 6.7 nm, respectively. Three-band white light was generated by hybridizing blue (430 nm), green (535 nm), and red (605 nm) emission. The color-rendering index (CRI) of the device was extremely improved by introducing the QDs. The CIE-1931 chromaticity coordinate, color temperature, and CRI of a white LED at 20 mA were (0.379, 0.368), 3969 K, and 90, respectively.

Theory of even-parity states and two-photon spectra of conjugated polymers

Science.gov (United States)

McWilliams, P. C. M.; Hayden, G. W.; Soos, Z. G.

1991-04-01

The two-photon absorption (TPA) spectrum of interacting π electrons in conjugated polymers is shown to be qualitatively different from any single-particle description, including the Hartree-Fock limit. Alternating transfer integrals t(1+/-δ) along the backbone lead to a weak TPA below the one-photon gap Eg for arbitrarily weak correlations at δ=0, for intermediate correlations at δ=0.07 in polyenes, and for strong correlations at any δtheory to Eg in the limit of strong correlations in Hubbard models and is around 1.5Eg for Pariser-Parr-Pople (PPP) parameters. The PPP model, which accounts for one- and two-photon excitations of finite polyenes, is extended to even-parity states in polydiacetylenes (PDA's), polyacetylene (PA), and polysilanes (PS's). Previous experimental data for PDA and PS support both the strong TPA above Eg and weak TPA slightly below Eg for δ=0.15 in PDA and above Eg for δ~0.3 in PS. The strong TPA expected around 1.5Eg in isolated PA strands shifts to ~Eg due to interchain π-electron dispersion forces. TPA intensities in correlated states are shown to reflect both ionicity and mean-square charge separation. The even-parity states of conjugated polymers, like those of polyenes, show qualitatively different features associated with electron-electron correlations.

Recent advances in polymer solar cells: realization of high device performance by incorporating water/alcohol-soluble conjugated polymers as electrode buffer layer.

Science.gov (United States)

He, Zhicai; Wu, Hongbin; Cao, Yong

2014-02-01

This Progress Report highlights recent advances in polymer solar cells with special attention focused on the recent rapid-growing progress in methods that use a thin layer of alcohol/water-soluble conjugated polymers as key component to obtain optimized device performance, but also discusses novel materials and device architectures made by major prestigious institutions in this field. We anticipate that due to drastic improvements in efficiency and easy utilization, this method opens up new opportunities for PSCs from various material systems to improve towards 10% efficiency, and many novel device structures will emerge as suitable architectures for developing the ideal roll-to-roll type processing of polymer-based solar cells. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thickness dependent structural ordering, degradation and metastability in polysilane thin films: A photoluminescence study on representative σ-conjugated polymers

International Nuclear Information System (INIS)

Urbánek, Pavel; Kuřitka, Ivo

2015-01-01

We present a fundamental experimental study based on the fluorescence investigation of thin σ-conjugated polymer films, where the dependence of optoelectrical properties and UV degradation on film thickness ranging from nano- to microscale was studied. Such extensive and detailed study was performed for the first time and observed spectral shifts in emission and excitation spectra and UV degradation retardation point towards the conclusions that there exists a threshold thickness where the material degradation behavior, electron delocalization and structure suddenly change. The development of well aligned polymeric chain structure between the nano- and micrometer thickness (on the mesoscale) was shown responsible for the manifested phenomena. The material thicker than critical 500 nm has extremely small Stokes' shift, maximum extended σ-delocalization along the silicon polymer backbone and exhibits remarkable UV degradation slowdown and self-recovery ability. On the contrary, the electronic properties of thin films below 80 nm resemble those of random coils in solutions. The films of moderate thickness show relatively steep transition between these two modes of structural ordering and resulting properties. Altogether, we consider this complex phenomenon as a consequence of the mesoscale effect, which is an only recently introduced concept in polymer thin films. - Highlights: • Photoluminescence was used as a tool for structural investigation of polysilanes. • Primary study of strong dependence of thin polymer film structure on mesoscale. • A mesoscale effect observed for the first time on sigma conjugated polymers. • Conjugation length is dramatically extended in thicker films than in nanoscale. • Self-recovery effect was shown to be dependent on the mesoscale as well.

Tunable Semiconducting Polymer Nanoparticles with INDT-Based Conjugated Polymers for Photoacoustic Molecular Imaging.

Science.gov (United States)

Stahl, Thomas; Bofinger, Robin; Lam, Ivan; Fallon, Kealan J; Johnson, Peter; Ogunlade, Olumide; Vassileva, Vessela; Pedley, R Barbara; Beard, Paul C; Hailes, Helen C; Bronstein, Hugo; Tabor, Alethea B

2017-06-21

Photoacoustic imaging combines both excellent spatial resolution with high contrast and specificity, without the need for patients to be exposed to ionizing radiation. This makes it ideal for the study of physiological changes occurring during tumorigenesis and cardiovascular disease. In order to fully exploit the potential of this technique, new exogenous contrast agents with strong absorbance in the near-infrared range, good stability and biocompatibility, are required. In this paper, we report the formulation and characterization of a novel series of endogenous contrast agents for photoacoustic imaging in vivo. These contrast agents are based on a recently reported series of indigoid π-conjugated organic semiconductors, coformulated with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, to give semiconducting polymer nanoparticles of about 150 nm diameter. These nanoparticles exhibited excellent absorption in the near-infrared region, with good photoacoustic signal generation efficiencies, high photostability, and extinction coefficients of up to three times higher than those previously reported. The absorption maximum is conveniently located in the spectral region of low absorption of chromophores within human tissue. Using the most promising semiconducting polymer nanoparticle, we have demonstrated wavelength-dependent differential contrast between vasculature and the nanoparticles, which can be used to unambiguously discriminate the presence of the contrast agent in vivo.

Control of charge carrier dynamics in disordered conjugated polymers

Energy Technology Data Exchange (ETDEWEB)

Hertel, Dirk [Physical Chemistry, University of Cologne, Luxemburgerstr. 116, 50939 Cologne, Germany, (Germany)

2011-07-01

We developed a new method to probe charge carrier mobility on ultrafast time scale. It is based on electric field induced second harmonic generation. The method is applied to prototypical amorphous conjugated polymers of the polyphenylene- and polyfluorene-type. Typically the carrier mobility in these organic polymers decreases with time in a power law fashion from about 1 cm{sup 2}Vs{sup -1} at 1 ps to its stationary value of about 10{sup -6} cm{sup 2}Vs{sup -1} in hundreds of ns. The dynamics of the mobility is discussed. It is shown, that in nanoscale devices the macroscopic mobility is not adequate to describe charge transport. We study the influence of disorder, morphology and temperature on ultrafast transport. At early times the transport is dominated by tunneling and disorder plays already an essential role. Comparison of transient photocurrents with Monte-Carlo simulation reveals that on-chain transport has to be invoked to rationalize our results. The hopping rates for intrachain transport are much larger compared with interchain transport. The results give access to essential transport properties for the development of advanced theoretical models and may help to design improved solar cells.

The Influence of Conjugated Polymer Side Chain Manipulation on the Efficiency and Stability of Polymer Solar Cells

DEFF Research Database (Denmark)

Heckler, Ilona Maria; Kesters, Jurgen; Defour, Maxime

2016-01-01

]thiazole (TzTz) acceptor units, were selected toward effective device scalability by roll-coating. The influence of the partial exchange (5% or 10%) of the solubilizing 2-hexyldecyloxy by alternative 2-phenylethoxy groups on efficiency and stability was investigated. With an increasing 2-phenylethoxy ratio...... studies under constant sun irradiance showed a diminishing initial degradation rate for the BT-based devices upon including the alternative side chains, whereas the (more stable) TzTz-based devices degraded at a faster rate from the start of the experiment upon partly exchanging the side chains. No clear......The stability of polymer solar cells (PSCs) can be influenced by the introduction of particular moieties on the conjugated polymer side chains. In this study, two series of donor-acceptor copolymers, based on bis(thienyl)dialkoxybenzene donor and benzo[c][1,2,5]thiadiazole (BT) or thiazolo[5,4-d...

Hepatoma targeting peptide conjugated bio-reducible polymer complexed with oncolytic adenovirus for cancer gene therapy.

Science.gov (United States)

Choi, Joung-Woo; Kim, Hyun Ah; Nam, Kihoon; Na, Youjin; Yun, Chae-Ok; Kim, SungWan

2015-12-28

Despite adenovirus (Ad) vector's numerous advantages for cancer gene therapy, such as high ability of endosomal escape, efficient nuclear entry mechanism, and high transduction, and therapeutic efficacy, tumor specific targeting and antiviral immune response still remain as a critical challenge in clinical setting. To overcome these obstacles and achieve cancer-specific targeting, we constructed tumor targeting bioreducible polymer, an arginine grafted bio-reducible polymer (ABP)-PEG-HCBP1, by conjugating PEGylated ABP with HCBP1 peptides which has high affinity and selectivity towards hepatoma. The ABP-PEG-HCBP1-conjugated replication incompetent GFP-expressing ad, (Ad/GFP)-ABP-PEG-HCBP1, showed a hepatoma cancer specific uptake and transduction compared to either naked Ad/GFP or Ad/GFP-ABP. Competition assays demonstrated that Ad/GFP-ABP-PEG-HCBP1-mediated transduction was specifically inhibited by HCBP1 peptide rather than coxsackie and adenovirus receptor specific antibody. In addition, ABP-PEG-HCBP1 can protect biological activity of Ad against serum, and considerably reduced both innate and adaptive immune response against Ad. shMet-expressing oncolytic Ad (oAd; RdB/shMet) complexed with ABP-PEG-HCBP1 delivered oAd efficiently into hepatoma cancer cells. The oAd/ABP-PEG-HCBP1 demonstrated enhanced cancer cell killing efficacy in comparison to oAd/ABP complex. Furthermore, Huh7 and HT1080 cancer cells treated with oAd/shMet-ABP-PEG-HCBP1 complex had significantly decreased Met and VEGF expression in hepatoma cancer, but not in non-hepatoma cancer. In sum, these results suggest that HCBP1-conjugated bioreducible polymer could be used to deliver oncolytic Ad safely and efficiently to treat hepatoma. Copyright © 2015 Elsevier B.V. All rights reserved.

Preparation of nanocrystals and nanocomposites of nanocrystal-conjugated polymer, and their photophysical properties in confined geometries

Energy Technology Data Exchange (ETDEWEB)

Xu, Jun [Iowa State Univ., Ames, IA (United States)

2007-01-01

Semiconductors nanocrystals (NCs), also called quantum dots (QDs), have attracted tremendous interest over the past decade in the fields of physics, chemistry, and engineering. Due to the quantum-confined nature of QDs, the variation of particle size provides continuous and predictable changes in fluorescence emission. On the other hand, conjugated polymers (CPs) have been extensively studied for two decades due to their semiconductor-like optical and electronic properties. The electron and energy transfer between NCs and CPs occur in solar cells and light emitting diodes (LEDs), respectively. Placing CPs in direct contact with a NC (i.e., preparing NC-CP nanocomposites) carries advantage over cases where NC aggregation dominates. Such NC-CP nanocomposites possess a well-defined interface that significantly promotes the charge or energy transfer between these two components. However, very few studies have centered on such direct integration. We prepared NCs and NC-CP nanocomposites based on heck coupling and investigated the energy and charge transfer between semiconductor NCs (i.e., CdSe QDs), CPs (i.e., poly(3-hexyl thiophene) (P3HT)) in the nanocomposites in confined geometries. Two novel strategies were used to confine NC and/or NC-CP nanocomposites: (a) directly immobilizing nanohybrids, QDs and nanorods in nanoscopic porous alumina membrane (PAM) , and (b) confining the QDs and CPs in sphere-on-flat geometry to induce self-assembly. While investigating the confinement effect, gradient concentric ring patterns of high regularity form spontaneously simply by allowing a droplet of solution containing either conjugated polymer or semiconductor nanocrystal in a consecutive stick-slip mothion in a confined geometry. Such constrained evaporation can be utilized as a simple, cheap, and robust strategy for self-assembling various materials with easily tailored optical and electronic properties into spatially ordered, two-dimensional patterns. These self

Geometrical relaxation of excitations in one-dimensional conjugated polymers; Giichijigen kyoeki kobunshi reiki jotai no shusa kozo kanwa

Energy Technology Data Exchange (ETDEWEB)

Yoshizawa, M. [Tohoku University, Sendai (Japan). Faculty of Engineering

1995-12-15

Large ultrafast optical nonlinearities in conjugated polymers have attracted much attention because of possible applications to nonlinear optical devices. One-dimensional systems such as conjugated polymers have localized excited states with geometrical relaxation. In this study, photoexcited states in polydiacetylene has been investigated by femtosecond Raman gain spectroscopy with 300-fs resolution. A new photoinduced Raman peak with lifetime of 1.5 ps has been observed at 1200cm{sup -1} for the first time. This peak indicates acetylene-like structure of the main chain relaxes to butatriene-like structure due to the formation of self-trapped exciting with the geometrical relaxation. The formation and decay kinetics of the Raman signals is consistent with the relaxation processes of exciting observed by femtosecond absorption spectroscopy. 8 refs., 5 figs.

Amplified spontaneous emission from the exciplex state of a conjugated polymer "PFO" in oleic acid

Science.gov (United States)

Idriss, Hajo; Taha, Kamal K.; Aldaghri, O.; Alhathlool, R.; AlSalhi, M. S.; Ibnaouf, K. H.

2016-09-01

The amplified spontaneous emission (ASE) characteristics of a conjugated polymer poly (9, 9-dioctylfluorenyl-2, 7-diyl) (PFO) in oleic acid have been studied under different concentrations and temperatures. Here, the ASE spectra of PFO in oleic acid have been obtained using a transverse cavity configuration where the conjugated PFO was pumped by laser pulses from the third harmonic of Nd: YAG laser (355 nm). The PFO in oleic acid produces ASE from an exciplex state - a new molecular species. The obtained results were compared with the PFO in benzene. Such ASE spectra from the exciplex state have not been observed for the PFO in benzene.

Roughening Conjugated Polymer Surface for Enhancing the Charge Collection Efficiency of Sequentially Deposited Polymer/Fullerene Photovoltaics

Directory of Open Access Journals (Sweden)

Yoonhee Jang

2015-08-01

Full Text Available A method that enables the formation of a rough nano-scale surface for conjugated polymers is developed through the utilization of a polymer chain ordering agent (OA. 1-Chloronaphthalene (1-CN is used as the OA for the poly(3-hexylthiophene-2,5-diyl (P3HT layer. The addition of 1-CN to the P3HT solution improves the chain ordering of the P3HT during the film formation process and increases the surface roughness of the P3HT film compared to the film prepared without 1-CN. The roughened surface of the P3HT film is utilized to construct a P3HT/fullerene bilayer organic photovoltaic (OPV by sequential solution deposition (SqSD without thermal annealing process. The power conversion efficiency (PCE of the SqSD-processed OPV utilizing roughened P3HT layer is 25% higher than that utilizing a plain P3HT layer. It is revealed that the roughened surface of the P3HT increases the heterojunction area at the P3HT/fullerene interface and this resulted in improved internal charge collection efficiency, as well as light absorption efficiency. This method proposes a novel way to improve the PCE of the SqSD-processed OPV, which can be applied for OPV utilizing low band gap polymers. In addition, this method allows for the reassessment of polymers, which have shown insufficient performance in the BSD process.

Correlations between structure and optoelectronic properties of conjugated polymers

International Nuclear Information System (INIS)

Sims, Marc

2002-01-01

An understanding of the fundamental processes that govern the electro-optical properties of conjugated polymers is essential for the improvement of polymer light-emitting diodes (PLEDs). The majority of the work in this thesis comprises a study on a group of sterically congested poly(para-phenylenevinylene)s (PPVs). It deals initially with the discovery and development of a highly ordered crystalline phase of a chloro-derived n-butyl analogue. A thorough structural characterisation of this phase is then made from the results of X-ray Diffraction, FT-IR and Raman scattering spectroscopies. The effective conjugation length of the chains that comprise the crystalline sample is longer than that found in two relatively disordered films, one that was prepared by spin-coating and the other by drop-casting. The spin-coated film was found to exhibit a higher photoluminescence quantum efficiency (PLQE) value than the drop-cast film, which has been attributed to the presence of lower density of aggregate states in the former. The PLQE of the crystalline sample is considerably lower than that of both of the films and this is ascribed to the rapid migration of excitons to defect sites e.g. grain boundaries. PLE measurements for all the samples strongly suggest that singlet exciton quenching is intimately related to energy migration processes. Through the study of a novel, reversible, light-induced photoluminescence quenching effect, it was concluded that photogenerated polaronic species can be trapped sufficiently deeply that they can stabilise for periods in excess of hours at low temperatures. Furthermore, it is demonstrated that the photogenerated polaronic species are less stable in the crystalline sample, yet most stable in the most disordered spin-cast film. It is shown by excitation into the tail states of the crystalline sample that the first vibronic feature in the quasi-resonantly excited PL spectrum undergoes gain. This phenomenon is not observed in the more

Synthesis of metalloporphyrin-based conjugated microporous polymer spheres directed by bipyridine-type ligands.

Science.gov (United States)

Ji, Guipeng; Yang, Zhenzhen; Zhao, Yanfei; Zhang, Hongye; Yu, Bo; Xu, Jilei; Xu, Huanjun; Liu, Zhimin

2015-04-30

Zinc porphyrin (TP-Zn)-based conjugated microporous polymer (Zn-CMP) spheres were obtained via Sonagashira-Hagihara cross coupling reactions between 5,10,15,20-tetrakis(4-ethynylphenyl)porphyrin-Zn(II) and brominated monomers directed by bidentate bipyridine (BP)-type ligands for the first time, and the sphere diameters could be adjusted from 320 to 740 nm. The coordination between BP and TP-Zn was proved to be the key to forming spheres.

Bis(thienothiophenyl) diketopyrrolopyrrole-based conjugated polymers with various branched alkyl side chains and their applications in thin-film transistors and polymer solar cells.

Science.gov (United States)

Shin, Jicheol; Park, Gi Eun; Lee, Dae Hee; Um, Hyun Ah; Lee, Tae Wan; Cho, Min Ju; Choi, Dong Hoon

2015-02-11

New thienothiophene-flanked diketopyrrolopyrrole and thiophene-containing π-extended conjugated polymers with various branched alkyl side-chains were successfully synthesized. 2-Octyldodecyl, 2-decyltetradecyl, 2-tetradecylhexadecyl, 2-hexadecyloctadecyl, and 2-octadecyldocosyl groups were selected as the side-chain moieties and were anchored to the N-positions of the thienothiophene-flanked diketopyrrolopyrrole unit. All five polymers were found to be soluble owing to the bulkiness of the side chains. The thin-film transistor based on the 2-tetradecylhexadecyl-substituted polymer showed the highest hole mobility of 1.92 cm2 V(-1) s(-1) due to it having the smallest π-π stacking distance between the polymer chains, which was determined by grazing incidence X-ray diffraction. Bulk heterojunction polymer solar cells incorporating [6,6]-phenyl-C71-butyric acid methyl ester as the n-type molecule and the additive 1,8-diiodooctane (1 vol %) were also constructed from the synthesized polymers without thermal annealing; the device containing the 2-octyldodecyl-substituted polymer exhibited the highest power conversion efficiency of 5.8%. Although all the polymers showed similar physical properties, their device performance was clearly influenced by the sizes of the branched alkyl side-chain groups.

Photoinduced charge and energy transfer in dye-doped conjugated polymers

International Nuclear Information System (INIS)

Veldman, Dirk; Bastiaansen, Jolanda J.A.M.; Langeveld-Voss, Bea M.W.; Sweelssen, Joergen; Koetse, Marc M.; Meskers, Stefan C.J.; Janssen, Rene A.J.

2006-01-01

Conjugated polymer-molecular dye blends of MDMO-PPV (poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene]) and PF1CVTP (poly[9,9-dioctylfluorene-2,7-diyl-alt-2,5-bis(2-thienyl-1-cyanovinyl) -1-(3',7= '-dimethyloctyloxy)-4-methoxybenzene-5'',5''-diyl]) with three dipyrrometheneboron difluoride (bodipy) dyes were studied by (time-resolved) fluorescence and photoinduced absorption spectroscopy to determine quantitatively the relation between the electronic HOMO and LUMO levels and the occurrence of energy or charge transfer after optical excitation. We find that for MDMO-PPV photoinduced charge transfer to the dyes occurs, while photoexcitation of PF1CVTP exclusively results in energy transfer. The differences can be rationalized by assuming that the energy of the charge separated state is 0.33-0.45 eV higher than the energy determined from oxidation and reduction potentials of donor and acceptor, respectively. This provides an important design rule to identify appropriate materials for polymer solar cells that can have a high open-circuit voltage

The Influence of Conjugated Polymer Side Chain Manipulation on the Efficiency and Stability of Polymer Solar Cells.

Science.gov (United States)

Heckler, Ilona M; Kesters, Jurgen; Defour, Maxime; Madsen, Morten V; Penxten, Huguette; D'Haen, Jan; Van Mele, Bruno; Maes, Wouter; Bundgaard, Eva

2016-03-09

The stability of polymer solar cells (PSCs) can be influenced by the introduction of particular moieties on the conjugated polymer side chains. In this study, two series of donor-acceptor copolymers, based on bis(thienyl)dialkoxybenzene donor and benzo[ c ][1,2,5]thiadiazole (BT) or thiazolo[5,4- d ]thiazole (TzTz) acceptor units, were selected toward effective device scalability by roll-coating. The influence of the partial exchange (5% or 10%) of the solubilizing 2-hexyldecyloxy by alternative 2-phenylethoxy groups on efficiency and stability was investigated. With an increasing 2-phenylethoxy ratio, a decrease in solar cell efficiency was observed for the BT-based series, whereas the efficiencies for the devices based on the TzTz polymers remained approximately the same. The photochemical degradation rate for PSCs based on the TzTz polymers decreased with an increasing 2-phenylethoxy ratio. Lifetime studies under constant sun irradiance showed a diminishing initial degradation rate for the BT-based devices upon including the alternative side chains, whereas the (more stable) TzTz-based devices degraded at a faster rate from the start of the experiment upon partly exchanging the side chains. No clear trends in the degradation behavior, linked to the copolymer structural changes, could be established at this point, evidencing the complex interplay of events determining PSCs' lifetime.

The Influence of Conjugated Polymer Side Chain Manipulation on the Efficiency and Stability of Polymer Solar Cells

Directory of Open Access Journals (Sweden)

Ilona M. Heckler

2016-03-01

Full Text Available The stability of polymer solar cells (PSCs can be influenced by the introduction of particular moieties on the conjugated polymer side chains. In this study, two series of donor-acceptor copolymers, based on bis(thienyldialkoxybenzene donor and benzo[c][1,2,5]thiadiazole (BT or thiazolo[5,4-d]thiazole (TzTz acceptor units, were selected toward effective device scalability by roll-coating. The influence of the partial exchange (5% or 10% of the solubilizing 2-hexyldecyloxy by alternative 2-phenylethoxy groups on efficiency and stability was investigated. With an increasing 2-phenylethoxy ratio, a decrease in solar cell efficiency was observed for the BT-based series, whereas the efficiencies for the devices based on the TzTz polymers remained approximately the same. The photochemical degradation rate for PSCs based on the TzTz polymers decreased with an increasing 2-phenylethoxy ratio. Lifetime studies under constant sun irradiance showed a diminishing initial degradation rate for the BT-based devices upon including the alternative side chains, whereas the (more stable TzTz-based devices degraded at a faster rate from the start of the experiment upon partly exchanging the side chains. No clear trends in the degradation behavior, linked to the copolymer structural changes, could be established at this point, evidencing the complex interplay of events determining PSCs’ lifetime.

Biocompatible Water Soluble Polyacrylic Acid Coated CdSe/Cu Quantum Dot Conjugates for Biomolecule Detection.

Science.gov (United States)

Gomaa, Ola M; Okasha, Aly; Hosni, Hany M; El-Hag Ali, Amr

2018-01-01

Biocompatible polyacrylic acid functionalized CdSe/Cu quantum dot conjugates were synthesized to be used for biomolecules detection. The study results demonstrate the conjugation of the 2.5-3 nm QD with gram negative bacteria with a low detection limit of 28 cfu/ml. The photoluminescence (PL) intensity was correlated to bacterial count, cellular proteins and exopolysaccharides in the tested samples. Confocal Scanning Laser Microscopy (CSLM) images showed significant QD uptake within the cells, both cytoplasm and DNA were the predominant targeted biomolecules, higher fluorescent uptake was shown in gram negative bacteria than that observed for gram positive bacteria. Moreover, PL showed that there was a distinction between live and dead cells as well as gram negative and gram positive cells. Cell viability was not affected even after 6 days (100% viability) rendering it a non-toxic QD. The method is simple and is performed in a single step within approximately 10 min as compared to multi-step protocols for classical microbial count or fluorescent dye staining. All the above results indicate that the CdSe/Cu-PAA QDs are suitable for biomolecule detection, bio-labeling and bioimaging applications.

Novel bioadhesive polymers as intra-articular agents: Chondroitin sulfate-cysteine conjugates.

Science.gov (United States)

Suchaoin, Wongsakorn; Bonengel, Sonja; Griessinger, Julia Anita; Pereira de Sousa, Irene; Hussain, Shah; Huck, Christian W; Bernkop-Schnürch, Andreas

2016-04-01

The aim of this study was to generate and characterize a chondroitin sulfate-cysteine conjugate (CS-cys) as a novel bioadhesive agent for intra-articular use. Mucoadhesive properties of synthesized CS-cys were investigated by rheological measurement of polymer-mucus mixture and rotating cylinder method, while bioadhesive features of CS-cys on porcine articular cartilage were evaluated via tensile studies. Thiolation was achieved by attachment of l-cysteine to CS via amide bond formation mediated by carbodiimide as a coupling reagent. The conjugate exhibited 421.17±35.14 μmol free thiol groups per gram polymer. The reduced CS-cys displayed 675.09±39.67 μmol free thiol groups per gram polymer after disulfide bonds reduction using tris(2-carboxyethyl)phosphine hydrochloride. The increase in dynamic viscosity of thiolated CS due to oxidative disulfide bond formation was demonstrated using capillary viscometer. The combination of CS-cys and mucus led to 4.57-fold increase in dynamic viscosity in comparison with mucus control. Furthermore, adhesion time to porcine mucosa of CS-cys-based test disk was enhanced by 2.48-fold compared to unmodified CS as measured by rotating cylinder method suggesting the interaction between thiomers and mucus gel layer via disulfide bonds formation. Tensile studies of thiolated CS on porcine articular cartilage showed 5.37- and 1.76-fold increase in the total work of adhesion and the maximum detachment force, respectively, in comparison with unmodified CS indicating bioadhesive features of CS-cys. Cytotoxicity of CS-cys was assessed in Caco-2 cells and rat primary articular chondrocytes using MTT and LDH release assay, thereby showing the safety of CS-cys at a concentration of 0.25% (w/v) in Caco-2 cells. Furthermore, 0.1% of CS-cys was found non-toxic to rat primary articular chondrocytes. According to these results, CS-cys provides improved bioadhesive properties that might be useful as an intra-articular agent for treatment of

Naphthalene Diimide Based n-Type Conjugated Polymers as Efficient Cathode Interfacial Materials for Polymer and Perovskite Solar Cells.

Science.gov (United States)

Jia, Tao; Sun, Chen; Xu, Rongguo; Chen, Zhiming; Yin, Qingwu; Jin, Yaocheng; Yip, Hin-Lap; Huang, Fei; Cao, Yong

2017-10-18

A series of naphthalene diimide (NDI) based n-type conjugated polymers with amino-functionalized side groups and backbones were synthesized and used as cathode interlayers (CILs) in polymer and perovskite solar cells. Because of controllable amine side groups, all the resulting polymers exhibited distinct electronic properties such as oxidation potential of side chains, charge carrier mobilities, self-doping behaviors, and interfacial dipoles. The influences of the chemical variation of amine groups on the cathode interfacial effects were further investigated in both polymer and perovskite solar cells. We found that the decreased electron-donating property and enhanced steric hindrance of amine side groups substantially weaken the capacities of altering the work function of the cathode and trap passivation of the perovskite film, which induced ineffective interfacial modifications and declining device performance. Moreover, with further improvement of the backbone design through the incorporation of a rigid acetylene spacer, the resulting polymers substantially exhibited an enhanced electron-transporting property. Upon use as CILs, high power conversion efficiencies (PCEs) of 10.1% and 15.2% were, respectively, achieved in polymer and perovskite solar cells. Importantly, these newly developed n-type polymers were allowed to be processed over a broad thickness range of CILs in photovoltaic devices, and a prominent PCE of over 8% for polymer solar cells and 13.5% for perovskite solar cells can be achieved with the thick interlayers over 100 nm, which is beneficial for roll-to-roll coating processes. Our findings contribute toward a better understanding of the structure-performance relationship between CIL material design and solar cell performance, and provide important insights and guidelines for the design of high-performance n-type CIL materials for organic and perovskite optoelectronic devices.

Effect of introduction of chondroitin sulfate into polymer-peptide conjugate responding to intracellular signals

Science.gov (United States)

Tomiyama, Tetsuro; Toita, Riki; Kang, Jeong-Hun; Koga, Haruka; Shiosaki, Shujiro; Mori, Takeshi; Niidome, Takuro; Katayama, Yoshiki

2011-09-01

We recently developed a novel tumor-targeted gene delivery system responding to hyperactivated intracellular signals. Polymeric carrier for gene delivery consists of hydrophilic neutral polymer as main chains and cationic peptide substrate for target enzyme as side chains, and was named polymer-peptide conjugate (PPC). Introduction of chondroitin sulfate (CS), which induces receptor-medicated endocytosis, into polymers mainly with a high cationic charge density such as polyethylenimine can increase tumor-targeted gene delivery. In the present study, we examined whether introduction of CS into PPC containing five cationic amino acids can increase gene expression in tumor cells. Size and zeta potential of plasmid DNA (pDNA)/PPC/CS complex were <200 nm and between -10 and -15 mV, respectively. In tumor cell experiments, pDNA/PPC/CS complex showed lower stability and gene regulation, compared with that of pDNA/PPC. Moreover, no difference in gene expression was identified between positive and negative polymer. These results were caused by fast disintegration of pDNA/PPC/CS complexes in the presence of serum. Thus, we suggest that introduction of negatively charged CS into polymers with a low charge density may lead to low stability and gene regulation of complexes.

Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer

KAUST Repository

Jiwuer, Jilili

2014-07-07

We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation a non-binding state, whereas the local density approximation predicts reasonable binding energies. The results coincide after inclusion of van der Waals corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization.

Non-covalent functionalization of single wall carbon nanotubes and graphene by a conjugated polymer

KAUST Repository

Jiwuer, Jilili; Abdurahman, Ayjamal; Gü lseren, Oğuz; Schwingenschlö gl, Udo

2014-01-01

We report first-principles calculations on the binding of poly[(9,9-bis-(6-bromohexylfluorene-2,7-diyl)-co-(benzene-1,4-diyl)] to a (8,0) single wall carbon nanotube (SWCNT) and to graphene. Considering different relative orientations of the subsystems, we find for the generalized gradient approximation a non-binding state, whereas the local density approximation predicts reasonable binding energies. The results coincide after inclusion of van der Waals corrections, which demonstrates a weak interaction between the polymer and SWCNT/graphene, mostly of van der Waals type. Accordingly, the density of states shows essentially no hybridization. The physisorption mechanism explains recent experimental observations and suggests that the conjugated polymer can be used for non-covalent functionalization.

Bispecific antibody complex pre-targeting and targeted delivery of polymer drug conjugates for imaging and therapy in dual human mammary cancer xenografts. Targeted polymer drug conjugates for cancer diagnosis and therapy

Energy Technology Data Exchange (ETDEWEB)

Khaw, Ban-An; Gada, Keyur S.; Patil, Vishwesh; Panwar, Rajiv; Mandapati, Savitri [Northeastern University, Department of Pharmaceutical Sciences, Bouve College of Health Sciences, School of Pharmacy, Boston, MA (United States); Hatefi, Arash [Rutgers University, Department of Pharmaceutics, New Brunswick, NJ (United States); Majewski, Stan [West Virginia University, Department of Radiology, Morgantown, WV (United States); Weisenberger, Andrew [Thomas Jefferson National Accelerator Facility, Jefferson Lab, Newport News, VA (United States)

2014-08-15

Doxorubicin, a frontline chemotherapeutic agent, limited by its cardiotoxicity and other tissue toxicities, was conjugated to N-terminal DTPA-modified polyglutamic acid (D-Dox-PGA) to produce polymer pro-drug conjugates. D-Dox-PGA or Tc-99 m labeled DTPA-succinyl-polylysine polymers (DSPL) were targeted to HER2-positive human mammary carcinoma (BT-474) in a double xenografted SCID mouse model also hosting HER2-negative human mammary carcinoma (BT-20). After pretargeting with bispecific anti-HER2-affibody-anti-DTPA-Fab complexes (BAAC), anti-DTPA-Fab or only phosphate buffered saline, D-Dox-PGA or Tc-99 m DSPL were administered. Positive therapeutic control mice were injected with Dox alone at maximum tolerated dose (MTD). Only BT-474 lesions were visualized by gamma imaging with Tc-99 m-DSPL; BT-20 lesions were not. Therapeutic efficacy was equivalent in mice pretargeted with BAAC/targeted with D-Dox-PGA to mice treated only with doxorubicin. There was no total body weight (TBW) loss at three times the doxorubicin equivalent MTD with D-Dox-PGA, whereas mice treated with doxorubicin lost 10 % of TBW at 2 weeks and 16 % after the second MTD injection leading to death of all mice. Our cancer imaging and pretargeted therapeutic approaches are highly target specific, delivering very high specific activity reagents that may result in the development of a novel theranostic application. HER/2 neu specific affibody-anti-DTPA-Fab bispecific antibody pretargeting of HER2 positive human mammary xenografts enabled exquisite targeting of polymers loaded with radioisotopes for molecular imaging and doxorubicin for effective therapy without the associating non-tumor normal tissue toxicities. (orig.)

Synthesis and Adsorption Study of BSA Surface Imprinted Polymer on CdS Quantum Dots

Science.gov (United States)

Tang, Ping-ping; Cai, Ji-bao; Su, Qing-de

2010-04-01

A new bovine serum albumin (BSA) surface imprinting method was developed by the incorporation of quantum dots (QDs) into molecularly imprinted polymers (MIP), which can offer shape selectivity. Preparation and adsorption conditions were optimized. Physical appearance of the QDs and QDs-MIP particles was illustrated by scanning electron microscope images. Photoluminescence emission of CdS was quenched when rebinding of the template. The quenching of photoluminescence emissions is presumably due to the fluorescence resonance energy transfer between quantum dots and BSA template molecules. The adsorption is compiled with Langmuir isotherm, and chemical adsorption is the rate-controlling step. The maximum adsorption capacity could reach 226.0 mg/g, which is 142.4 mg/g larger than that of undoped BSA MIP. This study demonstrates the validity of QDs coupled with MIP technology for analyzing BSA.

Emulsion-Based RIR-MAPLE Deposition of Conjugated Polymers: Primary Solvent Effect and Its Implications on Organic Solar Cell Performance.

Science.gov (United States)

Ge, Wangyao; Li, Nan K; McCormick, Ryan D; Lichtenberg, Eli; Yingling, Yaroslava G; Stiff-Roberts, Adrienne D

2016-08-03

Emulsion-based, resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) has been demonstrated as an alternative technique to deposit conjugated polymer films for photovoltaic applications; yet, a fundamental understanding of how the emulsion target characteristics translate into film properties and solar cell performance is unclear. Such understanding is crucial to enable the rational improvement of organic solar cell (OSC) efficiency and to realize the expected advantages of emulsion-based RIR-MAPLE for OSC fabrication. In this paper, the effect of the primary solvent used in the emulsion target is studied, both experimentally and theoretically, and it is found to determine the conjugated polymer cluster size in the emulsion as well as surface roughness and internal morphology of resulting polymer films. By using a primary solvent with low solubility-in-water and low vapor pressure, the surface roughness of deposited P3HT and PCPDTBT polymer films was reduced to 10 nm, and the efficiency of P3HT:PC61BM OSCs was increased to 3.2% (∼100 times higher compared to the first MAPLE OSC demonstration [ Caricato , A. P. ; Appl. Phys. Lett. 2012 , 100 , 073306 ]). This work unveils the mechanism of polymer film formation using emulsion-based RIR-MAPLE and provides insight and direction to determine the best ways to take advantage of the emulsion target approach to control film properties for different applications.

Oriented conjugates of monoclonal and single-domain antibodies with quantum dots for flow cytometry and immunohistochemistry diagnostic applications

Science.gov (United States)

Sukhanova, Alyona; Even-Desrumeaux, Klervi; Millot, Jean-Marc; Chames, Patrick; Baty, Daniel; Artemyev, Mikhail; Oleinikov, Vladimir; Cohen, Jacques H. M.; Nabiev, Igor

2012-03-01

Ideal diagnostic nanoprobes should not exceed 15 nm in size and should contain high-affinity homogeneously oriented capture molecules on their surface. An advanced procedure for antibody (Ab) reduction was used to cleave each Ab into two functional half-Abs, 75-kDa heavy-light chain fragments, each containing an intact antigen-binding site. Affinity purification of half-Abs followed by their linkage to quantum dots (QDs) yielded oriented QD-Ab conjugates whose functionality was considerably improved compared to those obtained using the standard protocols. Ultrasmall diagnostic nanoprobes were engineered through oriented conjugation of QDs with 13-kDa single-domain Abs (sdAbs) derived from llama IgG. sdAbs were tagged with QDs via an additional cysteine residue specifically integrated into the C-terminal region of sdAb using genetic engineering. This approach made it possible to obtain sdAb-QD nanoprobes <12 nm in diameter comprising four copies of sdAbs linked to the same QD in an oriented manner. sdAb-QD conjugates against carcinoembryonic antigen (CEA) and HER2 exhibited an extremely high specificity in flow cytometry; the quality of immunohistochemical labeling of biopsy samples was found to be superior to that of labeling according to the current "gold standard" protocols of anatomo-pathological practice. The nano-bioengineering approaches developed can be extended to oriented conjugation of Abs and sdAbs with different semiconductor, noble metal, or magnetic nanoparticles.

Real-time detection of metal ions using conjugated polymer composite papers.

Science.gov (United States)

Lee, Ji Eun; Shim, Hyeon Woo; Kwon, Oh Seok; Huh, Yang-Il; Yoon, Hyeonseok

2014-09-21

Cellulose, a natural polymeric material, has widespread technical applications because of its inherent structural rigidity and high surface area. As a conjugated polymer, polypyrrole shows practical potential for a diverse and promising range of future technologies. Here, we demonstrate a strategy for the real-time detection and removal of metal ions with polypyrrole/cellulose (PPCL) composite papers in solution. Simply, the conjugated polymer papers had different chemical/physical properties by applying different potentials to them, which resulted in differentiable response patterns and adsorption efficiencies for individual metal ions. First, large-area PPCL papers with a diameter of 5 cm were readily obtained via vapor deposition polymerization. The papers exhibited both mechanical flexibility and robustness, in which polypyrrole retained its redox property perfectly. The ability of the PPCL papers to recognize metal ions was examined in static and flow cells, in which real-time current change was monitored at five different applied potentials (+1, +0.5, 0, -0.5, and -1 V vs. Ag/AgCl). Distinguishable signals in the PPCL paper responses were observed for individual metal ions through principal component analysis. Particularly, the PPCL papers yielded unique signatures for three metal ions, Hg(ii), Ag(i), and Cr(iii), even in a real sample, groundwater. The sorption of metal ions by PPCL papers was examined in the flow system. The PPCL papers had a greatly superior adsorption efficiency for Hg(ii) compared to that of the other metal ions. With the strong demand for the development of inexpensive, flexible, light-weight, and environmentally friendly devices, the fascinating characteristics of these PPCL papers are likely to provide good opportunities for low-cost paper-based flexible or wearable devices.

Diketopyrrolopyrrole-Based Conjugated Polymer Entailing Triethylene Glycols as Side Chains with High Thin-Film Charge Mobility without Post-Treatments

Energy Technology Data Exchange (ETDEWEB)

Yang, Si-Fen [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; University of Chinese Academy of Sciences, Beijing 100049 P. R. China; Liu, Zi-Tong [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; Cai, Zheng-Xu [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; Dyson, Matthew J. [Department of Materials and Centre for Plastic Electronics, Imperial College London, London SW72AZ UK; Stingelin, Natalie [Department of Materials and Centre for Plastic Electronics, Imperial College London, London SW72AZ UK; Chen, Wei [Materials Science Division, Argonne National Laboratory, 9700 Cass Avenue Lemont IL 60439 USA; Institute for Molecular Engineering, The University of Chicago, 5640 South Ellis Avenue Chicago IL 60637 USA; Ju, Hua-Jun [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; Zhang, Guan-Xin [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; Zhang, De-Qing [Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 P. R. China; University of Chinese Academy of Sciences, Beijing 100049 P. R. China

2017-04-18

Side chain engineering of conjugated donor-acceptor polymers is a new way to manipulate their optoelectronic properties. Two new diketopyrrolopyrrole (DPP)-terthiophene-based conjugated polymers PDPP3T-1 and PDPP3T-2, with both hydrophilic triethylene glycol (TEG) and hydrophobic alkyl chains, are reported. It is demonstrated that the incorporation of TEG chains has a significant effect on the interchain packing and thin-film morphology with noticeable effect on charge transport. Polymer chains of PDPP3T-1 in which TEG chains are uniformly distributed can self-assemble spontaneously into a more ordered thin film. As a result, the thin film of PDPP3T-1 exhibits high saturated hole mobility up to 2.6 cm(2) V-1 s(-1) without any post-treatment. This is superior to those of PDPP3T with just alkyl chains and PDPP3T-2. Moreover, the respective field effect transistors made of PDPP3T-1 can be utilized for sensing ethanol vapor with high sensitivity (down to 100 ppb) and good selectivity.

Fabrication of multicolor fluorescent polyvinyl alcohol through surface modification with conjugated polymers by oxidative polymerization

Science.gov (United States)

Hai, Thien An Phung; Sugimoto, Ryuichi

2018-06-01

A simple method for the preparation of multicolor polyvinyl alcohol (PVA) by chemical oxidative polymerization is introduced. The PVA surface was successfully modified with conjugated polymers composed of 3-hexylthiophene (3HT) and fluorene (F). The incorporation of the 3HT/F copolymer onto the PVA surface was confirmed by Fourier-transform infrared (FT-IR), ultraviolet-visible (UV-vis), and fluorescence spectroscopies, X-ray diffraction (XRD), as well as thermogravimetric analysis (TGA), contact angle, and field-emission scanning electron microscopy (FE-SEM) coupled with energy dispersive X-ray (EDX) analysis. Different 3HT/F ratios on the PVA surface result in optical properties that include multicolor-emission and absorption behavior. The color of the resultant (3HT/F)-g-PVA shifted from red to blue, and the quantum yield increased with increasing F content. The surface hydrophobicity of the modified PVA increased significantly through grafting with the conjugated polymers, with the water contact angle increasing by 30° compared to pristine PVA. The PVA XRD peaks were less intense following surface modification. Thermogravimetric analyses reveal that the thermal stability of the PVA decreases as a result of grafting with the 3HT/F copolymers.

Alkylated indacenodithieno[3,2-b]thiophene-based all donor ladder-type conjugated polymers for organic thin film transistors

KAUST Repository

Lu, Rimei; Han, Yang; Zhang, Weimin; Zhu, Xiuxiu; Fei, Zhuping; Hodsden, Thomas; Anthopoulos, Thomas D.; Heeney, Martin

2018-01-01

We report the synthesis of a series of indacenodithieno[3,2-b]thiophene (IDTT) based conjugated polymers by copolymerization with three different electron rich co-monomers [thiophene (T), thieno[3,2-b]thiophene (TT) and dithieno[3,2-b:2',3'-d

Immunoglobulin and enzyme-conjugated dextran polymers enhance u-PAR staining intensity of carcinoma cells in peripheral blood smears

DEFF Research Database (Denmark)

Werther, K; Normark, M; Hansen, B F

1999-01-01

phenotyping of disseminated carcinoma cells in bone marrow and peripheral blood smears. In the first step, the cells were incubated with antibodies against urokinase plasminogen activator receptor (u-PAR) and subsequently with secondary antibodies conjugated to peroxidase-labeled dextran polymers. A brown...

Anomalous carrier life-time relaxation mediated by head group interaction in surface anchored MnSe quantum dots conjugated with albumin proteins

Energy Technology Data Exchange (ETDEWEB)

Sarma, Runjun; Mohanta, Dambarudhar, E-mail: best@tezu.ernet.in

2017-02-01

We report on the radiative emission decay dynamics of a less known, γ-phase manganese selenide quantum dot system (MnSe QDs) subjected to bio-functionalization. A short-ligand thioglycolic acid (TGA), and a long-chain sodium dodecyl sulfate (SDS) surfactants were used as surface anchors prior bioconjugation with albumin proteins (BSA). Time resolved photoluminescence (TR-PL) spectra of the QDs have revealed bi-exponential decay trends with the fast (τ{sub 1}) and slow (τ{sub 2}) decay parameters assigned to the core state recombination and surface trapped excitons; respectively. The average lifetime (τ{sub avg}) was found to get shortened from a value of ∼0.87 ns–0.72 ns in unconjugated and BSA conjugated MnSe-TGA QDs; respectively. Conversely, MnSe-SDS QDs with BSA conjugation exhibited nearly four-fold enhancement of τ{sub avg} with respect to its unconjugated counterpart. Moreover, a considerable amount of Förster resonance energy transfer (FRET) was found to occur from the TGA coated MnSe QDs to BSA and with an ensuing efficiency of ∼61%. The origin of anomalous carrier life-time relaxation features has also been encountered through a simplified model as regards head group interaction experienced by the MnSe QDs with different surfactant types. Exploiting luminescence decay characteristics of a magneto-fluorescent candidate could find immense scope in diverse biological applications including assays, labeling and imaging. - Highlights: • Surface anchored manganese selenide quantum dots (MnSe QDs) have been synthesized via a physico-chemical reduction route. • Time resolved luminescence spectra of the QDs have displayed bi-exponential decay trend. • Thioglycolic acid (TGA) coated QDs exhibited shorter lifetime as compared to sodium dodecyl sulfo-succinate (SDS) coated ones. • Upon BSA conjugation, the average life time is four-fold enhanced in MnSe-SDS QDs. • An efficient FRET process has been revealed in BSA conjugated TGA coated MnSe QDs.

A New Property of Conjugated Polymer PFP: Catalytic Degradation of Methylene Blue Aqueous Solution

Institute of Scientific and Technical Information of China (English)

无

2005-01-01

A new property of conjugated polymer poly(furancarbinol-co-phenol)(PFP) was studied.The target copolymer was used as a catalyst after proper heating treatment. And dye methylene blue (MB) could be fully degraded and largely mineralized on PFP, under natural light or even in dark, in a few minutes. Furthermore, the catalytic activity could be preserved after several runs and the catalyst was readily separated. The effect of calcination temperature was also observed.

Semi-metallic, strong and stretchable wet-spun conjugated polymer microfibers

KAUST Repository

Zhou, Jian

2015-01-21

A dramatic improvement in electrical conductivity is necessary to make conductive polymer fibers viable candidates in applications such as flexible electrodes, conductive textiles, and fast-response sensors and actuators. In this study, high-performance poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) conjugated polymer microfibers were fabricated via wet-spinning followed by hot-drawing. Due to the combined effects of the vertical hot-drawing process and doping/de-doping the microfibers with ethylene glycol (EG), we achieved a record electrical conductivity of 2804 S cm−1. This is, to the best of our knowledge, a six-fold improvement over the best previously reported value for PEDOT/PSS fibers (467 S cm−1) and a two-fold improvement over the best values for conductive polymer films treated by EG de-doping (1418 S cm−1). Moreover, we found that these highly conductive fibers experience a semiconductor–metal transition at 313 K. They also have superior mechanical properties with a Young\\'s modulus up to 8.3 GPa, a tensile strength reaching 409.8 MPa and a large elongation before failure (21%). The most conductive fiber also demonstrates an extraordinary electrical performance during stretching/unstretching: the conductivity increased by 25% before the fiber rupture point with a maximum strain up to 21%. Simple fabrication of the semi-metallic, strong and stretchable wet-spun PEDOT/PSS microfibers described here could make them available for conductive smart electronics.

Driving High-Performance n- and p-type Organic Transistors with Carbon Nanotube/Conjugated Polymer Composite Electrodes Patterned Directly from Solution

KAUST Repository

Hellstrom, Sondra L.; Jin, Run Zhi; Stoltenberg, Randall M.; Bao, Zhenan

2010-01-01

We report patterned deposition of carbon nanotube/conjugated polymer composites from solution with high nanotube densities and excellent feature resolution. Such composites are suited for use as electrodes in high-performance transistors

Distinct Interfacial Fluorescence in Oil-in-Water Emulsions via Exciton Migration of Conjugated Polymers.

Science.gov (United States)

Koo, Byungjin; Swager, Timothy M

2017-09-01

Commercial dyes are extensively utilized to stain specific phases for the visualization applications in emulsions and bioimaging. In general, dyes emit only one specific fluorescence signal and thus, in order to stain various phases and/or interfaces, one needs to incorporate multiple dyes and carefully consider their compatibility to avoid undesirable interactions with each other and with the components in the system. Herein, surfactant-type, perylene-endcapped fluorescent conjugated polymers that exhibit two different emissions are reported, which are cyan in water and red at oil-water interfaces. The interfacially distinct red emission results from enhanced exciton migration from the higher-bandgap polymer backbone to the lower-bandgap perylene endgroup. The confocal microscopy images exhibit the localized red emission exclusively from the circumference of oil droplets. This exciton migration and dual fluorescence of the polymers in different physical environments can provide a new concept of visualization methods in many amphiphilic colloidal systems and bioimaging. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stepwise Assembly and Characterization of DNA Linked Two-Color Quantum Dot Clusters.

Science.gov (United States)

Coopersmith, Kaitlin; Han, Hyunjoo; Maye, Mathew M

2015-07-14

The DNA-mediated self-assembly of multicolor quantum dot (QD) clusters via a stepwise approach is described. The CdSe/ZnS QDs were synthesized and functionalized with an amphiphilic copolymer, followed by ssDNA conjugation. At each functionalization step, the QDs were purified via gradient ultracentrifugation, which was found to remove excess polymer and QD aggregates, allowing for improved conjugation yields and assembly reactivity. The QDs were then assembled and disassembled in a stepwise manner at a ssDNA functionalized magnetic colloid, which provided a convenient way to remove unreacted QDs and ssDNA impurities. After assembly/disassembly, the clusters' optical characteristics were studied by fluorescence spectroscopy and the assembly morphology and stoichiometry was imaged via electron microscopy. The results indicate that a significant amount of QD-to-QD energy transfer occurred in the clusters, which was studied as a function of increasing acceptor-to-donor ratios, resulting in increased QD acceptor emission intensities compared to controls.

Well-defined degradable brush polymer-drug conjugates for sustained delivery of Paclitaxel.

Science.gov (United States)

Yu, Yun; Chen, Chih-Kuang; Law, Wing-Cheung; Mok, Jorge; Zou, Jiong; Prasad, Paras N; Cheng, Chong

2013-03-04

To achieve a conjugated drug delivery system with high drug loading but minimal long-term side effects, a degradable brush polymer-drug conjugate (BPDC) was synthesized through azide-alkyne click reaction of acetylene-functionalized polylactide (PLA) with azide-functionalized paclitaxel (PTXL) and poly(ethylene glycol) (PEG). Well-controlled structures of the resulting BPDC and its precursors were verified by (1)H NMR and gel permeation chromatography (GPC) characterizations. With nearly quantitative click efficiency, drug loading amount of the BPDC reached 23.2 wt %. Both dynamic light scattering (DLS) analysis and transmission electron microscopy (TEM) imaging indicated that the BPDC had a nanoscopic size around 10-30 nm. The significant hydrolytic degradability of the PLA backbone of the BPDC was confirmed by GPC analysis of its incubated solution. Drug release study showed that PTXL moieties can be released through the cleavage of the hydrolyzable conjugation linkage in pH 7.4 at 37 °C, with 50% release in about 22 h. As illustrated by cytotoxicity study, while the polymeric scaffold of the BPDC is nontoxic, the BPDC exhibited higher therapeutic efficacy toward MCF-7 cancer cells than free PTXL at 0.1 and 1 μg/mL. Using Nile red as encapsulated fluorescence probe, cell uptake study showed effective internalization of the BPDC into the cells.

pH-responsive fluorescence chemical sensor constituted by conjugated polymers containing pyridine rings.

Science.gov (United States)

Adachi, Naoya; Kaneko, Yuki; Sekiguchi, Kazuki; Sugiyama, Hiroki; Sugeno, Masafumi

2015-12-01

Poly(p-pyridinium phenylene ethynylene)s (PPyPE) functionalized with alternating donor-acceptor repeat units were synthesized by a Pd-catalyzed Sonogashira coupling reaction between diethynyl monomer and di-iodopyridine for use as a pH-responsive fluorescence chemical sensor. The synthesized PPyPE, containing pyridine units, was characterized by FT-IR, (1)H and (13)C NMR, UV-visible and fluorescence spectroscopies. We investigated the relationship between changes of optical properties and protonation/deprotonation of PPyPE containing pyridine units in solution. Addition of HCl decreased and red-shifted the fluorescence intensity of the conjugated polymers that contained pyridine rings; fluorescence intensity of the polymers increased upon addition of NaOH solution. The synthesized PPyPE was found to be an effective and reusable chemical sensor for pH sensing. Copyright © 2015 John Wiley & Sons, Ltd.

Siloxane-Terminated Solubilizing Side Chains: Bringing Conjugated Polymer Backbones Closer and Boosting Hole Mobilities in Thin-Film Transistors

KAUST Repository

Mei, Jianguo

2011-12-21

We introduce a novel siloxane-terminated solubilizing group and demonstrate its effectiveness as a side chain in an isoindigo-based conjugated polymer. An average hole mobility of 2.00 cm 2 V -1 s -1 (with a maximum mobility of 2.48 cm 2 V -1 s -1), was obtained from solution-processed thin-film transistors, one of the highest mobilities reported to date. In contrast, the reference polymer with a branched alkyl side chain gave an average hole mobility of 0.30 cm 2 V -1 s -1 and a maximum mobility of 0.57 cm 2 V -1 s -1. This is largely explained by the polymer packing: our new polymer exhibited a π-π stacking distance of 3.58 Å, while the reference polymer showed a distance of 3.76 Å. © 2011 American Chemical Society.

In vivo study of immunogenicity and kinetic characteristics of a quantum dot-labelled baculovirus.

Science.gov (United States)

Wang, Meng; Zheng, Zhenhua; Meng, Jin; Wang, Han; He, Man; Zhang, Fuxian; Liu, Yan; Hu, Bin; He, Zike; Hu, Qinxue; Wang, Hanzhong

2015-09-01

Nanomaterials conjugated with biomacromolecules, including viruses, have great potential for in vivo applications. Therefore, it is important to evaluate the safety of nanoparticle-conjugated macromolecule biomaterials (Nano-mbio). Although a number of studies have assessed the risks of nanoparticles and macromolecule biomaterials in living bodies, only a few of them investigated Nano-mbios. Here we evaluated the in vivo safety profile of a quantum dot-conjugated baculovirus (Bq), a promising new Nano-mbio, in mice. Each animal was injected twice intraperitoneally with 50 μg virus protein labelled with around 3*10(-5)nmol conjugated qds. Control animals were injected with PBS, quantum dots, baculovirus, or a mixture of quantum dots and baculovirus. Blood, tissues and body weight were analysed at a series of time points following both the first and the second injections. It turned out that the appearance and behaviour of the mice injected with Bq were similar to those injected with baculovirus alone. However, combination of baculovirus and quantum dot (conjugated or simply mixed) significantly induced stronger adaptive immune responses, and lead to a faster accumulation and longer existence of Cd in the kidneys. Thus, despite the fact that both quantum dot and baculovirus have been claimed to be safe in vivo, applications of Bq in vivo should be cautious. To our knowledge, this is the first study examining the interaction between a nanoparticle-conjugated virus and a living body from a safety perspective, providing a basis for in vivo application of other Nano-mbios. Copyright © 2015 Elsevier Ltd. All rights reserved.

Thiazoloisoindigo: a Building Block that Merges the Merits of Thienoisoindigo and Diazaisoindigo for Conjugated Polymers.

Science.gov (United States)

Wan, Xiaobo; Li, Chenchen; Wang, Xiao; Hio-Ieng, Un; Peng, Jiawei; Lan, Zhenggang; Cai, Mian; Pei, Jian; Wang, Jieyu

2018-04-24

Thiazoloisoindigo, a novel structural variation of isoindigo, is for the first time utilized to synthesize conjugated polymers. Polymer based on thiazoloisoindigo merges the advantages of the one based on thienoisoindigo and diazaisoindigo: It not only exhibits a greatly red shifted UV-vis absorption to the near-infrared region due to its strong tendency to form quinoidal structures, similar to that based on thienoisoindigo, but also shows excellent ambipolar mobility (hole 3.93 and electron 1.07 cm2 V-1 s-1, respectively) in organic field-effect transistors (OFETs), superior than that based on diazaisoindigo, showing the strong electron-withdrawing capability of thiazoloisoindigo. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nature of the Binding Interactions between Conjugated Polymer Chains and Fullerenes in Bulk Heterojunction Organic Solar Cells

KAUST Repository

Ravva, Mahesh Kumar

2016-10-24

Blends of π-conjugated polymers and fullerene derivatives are ubiquitous as the active layers of organic solar cells. However, a detailed understanding of the weak noncovalent interactions at the molecular level between the polymer chains and fullerenes is still lacking and could help in the design of more efficient photoactive layers. Here, using a combination of long-range corrected density functional theory calculations and molecular dynamic simulations, we report a thorough characterization of the nature of binding between fullerenes (C60 and PC61BM) and poly(benzo[1,2-b:4,5-b′]dithiophene–thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) chains. We illustrate the variations in binding strength when the fullerenes dock on the electron-rich vs electron-poor units of the polymer as well as the importance of the role played by the polymer and fullerene side chains and the orientations of the PC61BM molecules with respect to the polymer backbones.

Photoluminescence of double core/shell infrared (CdSeTe)/ZnS quantum dots conjugated to Pseudo rabies virus antibodies

Science.gov (United States)

Torchynska, T. V.; Casas Espinola, J. L.; Jaramillo Gómez, J. A.; Douda, J.; Gazarian, K.

2013-06-01

Double core CdSeTe/ZnS quantum dots (QDs) with emission at 800 nm (1.60 eV) have been studied by photoluminescence (PL) and Raman scattering methods in the non-conjugated state and after the conjugation to the Pseudo rabies virus (PRV) antibodies. The transformation of PL spectra, stimulated by the electric charge of antibodies, has been detected for the bioconjugated QDs. Raman scattering spectra are investigated with the aim to reveal the CdSeTe core compositions. The double core QD energy diagrams were designed that help to analyze the PL spectra and their transformation at the bioconjugation. It is revealed that the interface in double core QDs has the type II quantum well character that permits to explain the near IR optical transition (1.60 eV) in the double core QDs. It is shown that the essential transformation of PL spectra is useful for the study of QD bioconjugation with specific antibodies and can be a powerful technique in early medical diagnostics.

Synthesis, characterization, mucoadhesion and biocompatibility of thiolated carboxymethyl dextran-cysteine conjugate.

Science.gov (United States)

Shahnaz, G; Perera, G; Sakloetsakun, D; Rahmat, D; Bernkop-Schnürch, A

2010-05-21

This study was aimed at improving the mucoadhesive properties of carboxymethyl dextran by the covalent attachment of cysteine. Mediated by a carbodiimide, l-cysteine was covalently attached to the polymer. The resulting CMD-cysteine conjugate (CMD-(273) conjugate) displayed 273+/-20 micromol thiol groups per gram of polymer (mean+/-S.D.; n=3). Within 2h the viscosity of an aqueous mucus/CMD-(273) conjugate mixture pH 7.4 increased at 37 degrees C by more than 85% compared to a mucus/carboxymethyl dextran mixture indicating enlarged interactions between the mucus and the thiolated polymer. Due to the immobilization of cysteine, the swelling velocity of the polymer was significantly accelerated (ppolymer disintegrated within 15 min, whereas tablets of the CMD-(273) conjugate remained stable for 160 min (means+/-S.D.; n=3). Results from LDH and MTT assays on Caco-2 cells revealed 4.96+/-0.98% cytotoxicity and 94.1+/-0.9% cell viability for the CMD-(273) conjugate, respectively. Controlled release of model compound from CMD-(273) conjugate tablets was observed over 6h. These findings suggest that CMD-(273) conjugate is a promising novel polymer for drug delivery systems providing improved mucoadhesive and cohesive properties, greater stability and biocompatibility. Copyright 2010 Elsevier B.V. All rights reserved.

Polymer-coated quantum dots

NARCIS (Netherlands)

Tomczak, N.; Liu, Rongrong; Vancso, Gyula J.

2013-01-01

Quantum Dots (QDs) are semiconductor nanocrystals with distinct photophysical properties finding applications in biology, biosensing, and optoelectronics. Polymeric coatings of QDs are used primarily to provide long-term colloidal stability to QDs dispersed in solutions and also as a source of

Charge carrier mobility, photovoltaic, and electroluminescent properties of anthracene-based conjugated polymers bearing randomly distributed side chains

Czech Academy of Sciences Publication Activity Database

Usluer, Ö.; Kästner, C.; Abbas, M.; Ulbricht, C.; Cimrová, Věra; Wild, A.; Birckner, E.; Tekin, N.; Sariciftci, N. S.; Hoppe, H.; Rathgeber, S.; Egbe, D. A. M.

2012-01-01

Roč. 50, č. 16 (2012), s. 3425-3436 ISSN 0887-624X R&D Projects: GA MŠk(CZ) 1M06031 Institutional research plan: CEZ:AV0Z40500505 Keywords : conjugated polymers * organic field-effect transistors * organic solar cells Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.543, year: 2012

Diffuse x-ray scattering study of interfacial structure of self-assembled conjugated polymers

International Nuclear Information System (INIS)

Wang Jun; Park, Y.J.; Lee, K.-B.; Hong, H.; Davidov, D.

2002-01-01

The interfacial structures of self-assembled heterostructures through alternate deposition of conjugated and nonconjugated polymers were studied by x-ray reflectivity and nonspecular scattering. We found that the interfacial width including the effects of both interdiffusion and interfacial roughness (correlated) was mainly contributed by the latter one. The self-assembled deposition induced very small interdiffusion between layers. The lateral correlation length ξ parallel grew as a function of deposition time (or film thickness) described by a power law ξ parallel ∝t β/H and was also observed from the off-specular scattering

Difluorobenzothiadiazole based two-dimensional conjugated polymers with triphenylamine substituted moieties as pendants for bulk heterojunction solar cells

Directory of Open Access Journals (Sweden)

W. H. Lee

2017-11-01

Full Text Available Three donor/acceptor (D/A-type two-dimensional polythiophenes (PTs; PBTFA13, PBTFA12, PBTFA11 featuring difluorobenzothiadiazole (DFBT derivatives as the conjugated (acceptor units in the polymer backbone and tertbutyl–substituted triphenylamine (tTPA-containing moieties as (donor pendants have been synthesized and characterized. These PTs exhibited good thermal stabilities, broad absorption spectra, and narrow optical band gaps. The cutoff wavelength of the UV–Vis absorption band was red-shifted upon increasing the content of the DFBT units in the PTs. Bulk heterojunction solar cells having an active layer comprising blends of the PTs and fullerene derivatives [6,6] phenyl-C61/71-butyric acid methyl ester (PC61BM/PC71BM were fabricated; their photovoltaic performance was strongly dependent on the content of the DFBT derivative in the PT. Incorporating a suitable content of the DFBT derivative in the polymer backbone enhanced the solar absorption ability and conjugation length of the PTs. The photovoltaic properties of the PBTFA13-based solar cells were superior to those of the PBTFA11- and PBTFA12-based solar cells.

Siloxane-Terminated Solubilizing Side Chains: Bringing Conjugated Polymer Backbones Closer and Boosting Hole Mobilities in Thin-Film Transistors

KAUST Repository

Mei, Jianguo; Kim, Do Hwan; Ayzner, Alexander L.; Toney, Michael F.; Bao, Zhenan

2011-01-01

We introduce a novel siloxane-terminated solubilizing group and demonstrate its effectiveness as a side chain in an isoindigo-based conjugated polymer. An average hole mobility of 2.00 cm 2 V -1 s -1 (with a maximum mobility of 2.48 cm 2 V -1 s -1

Conjugation of quantum dots on carbon nanotubes for medical diagnosis and treatment

Directory of Open Access Journals (Sweden)

Madani SY

2013-03-01

/g allows drugs to be loaded into the tube and released once inside the cancer cell. Many research laboratories, including our own, are investigating the conjugation of QDs to CNTs to allow localization of the cancer cells in the patient, by imaging with QDs, and subsequent cell killing, via drug release or thermal treatment. This is an area of huge interest and future research and therapy will focus on the multimodality of nanoparticles. In this review, we seek to explore the biomedical applications of QDs conjugated to CNTs, with a particular emphasis on their use as therapeutic platforms in oncology. Keywords: carbon nanotubes, quantum dots, cancer, photothermal therapy, drug delivery, cytotoxicity, near-infrared light

Optical sensing of 3-phenoxybenzoic acid as a pyrethroid pesticides exposure marker by surface imprinting polymer capped on manganese-doped zinc sulfide quantum dots

Directory of Open Access Journals (Sweden)

Vivek Pandey

2015-09-01

Full Text Available The present communication deals with the synthesis of luminescent Mn-doped ZnS quantum dots (QDs anchored to surface imprinted polymer for the optical sensing of 3-phenoxy benzoic acid (3-PBA in urine samples. The combination of sensing and surface functionalization not only improves the selectivity of the method, but also increases the optosensing ability of the material for non-phosphorescent substances. The developed material was utilized for the selective and sensitive detection of 3-PBA in urine samples. The proposed method shows good linearity with a regression coefficient (R2 of 0.98. The limit of detection was found to be 0.117 μM. The method has an acceptable precision and accuracy which are found to be less than 8% and 80–90% respectively at three different concentrations. The quenching constant of quantum dot-molecular imprinted polymer was found to be 3.4 times higher to that of the quantum dot-non imprinted polymer (QD-NIP as calculated by Stern–Volmer equation. The sensing method developed has shown immense utility to detect 3-PBA in complex biological samples like urine.

Ultrafast photo-induced nuclear relaxation of a conformationally disordered conjugated polymer probed with transient absorption and femtosecond stimulated Raman spectroscopies

Energy Technology Data Exchange (ETDEWEB)

Yu, Wenjian; Donohoo-Vallett, Paul J.; Zhou, Jiawang; Bragg, Arthur E., E-mail: artbragg@jhu.edu [Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218 (United States)

2014-07-28

A combination of transient absorption (TAS) and femtosecond stimulated Raman (FSRS) spectroscopies were used to interrogate the photo-induced nuclear relaxation dynamics of poly(3-cyclohexyl,4-methylthiophene) (PCMT). The large difference in inter-ring dihedral angles of ground and excited-state PCMT make it an ideal candidate for studying large-amplitude vibrational relaxation associated with exciton trapping. Spectral shifting in the S{sub 1} TA spectra on sub-ps timescales (110 ± 20 and 800 ± 100 fs) is similar to spectroscopic signatures of excited-state relaxation observed with related photoexcited conjugated polymers and which have been attributed to exciton localization and a combination of resonant energy transfer and torsional relaxation, respectively. Measurements made with both techniques reveal fast PCMT S{sub 1} decay and triplet formation (τ{sub S1} = 25–32 ps), which is similar to the excited-state dynamics of short oligothiophenes and highly twisted polyconjugated molecules. On ultrafast timescales FSRS of S{sub 1} PCMT offers a new perspective on the nuclear dynamics that underlie localization of excitons in photoexcited conjugated polymers: Spectral dynamics in the C=C stretching region (1400–1600 cm{sup −1}) include a red-shift of the in-phase C=C stretching frequency, as well as a change in the relative intensity of in-phase and out-of-phase stretch intensities on a timescale of ∼100 fs. Both changes indicate an ultrafast vibrational distortion that increases the conjugation length in the region of the localized excitation and are consistent with exciton self-localization or trapping. Wavelength-dependent excited-state FSRS measurements further demonstrate that the C=C stretching frequency provides a useful spectroscopic handle for interrogating the degree of delocalization in excited conjugated polymers given the selectivity achieved via resonance enhancement.

Conjugation of nano and quantum materials with bovine serum albumin (BSA) to study their biological potential

Energy Technology Data Exchange (ETDEWEB)

Singh, Suman, E-mail: sumansingh01@gmail.com [Central Scientific Instruments Organisation (CSIR-CSIO), Chandigarh (India); Kaur, Rajnish; Chahal, Jitender; Devi, P. [Central Scientific Instruments Organisation (CSIR-CSIO), Chandigarh (India); Jain, D.V.S. [Panjab University, Chandigarh (India); Singla, M.L., E-mail: singla_min@yahoo.co.in [Central Scientific Instruments Organisation (CSIR-CSIO), Chandigarh (India)

2013-09-15

Conjugates of gold nanoparticles (AuNPs) and semiconductor quantum dots (CdS/T) have been synthesized with bovine serum albumin (BSA) using wet chemistry. The optical properties of nano and quantum materials and their BSA conjugate have been studied using UV–Visible and Fluorescence spectroscopy. UV–Visible spectrum of pure BSA showed an absorption maximum at 278 nm, which showed blue shift after its conjugation with nano and quantum materials. Increased concentration of AuNPs during conjugation resulted in broadening of BSA peak (278 nm), which can be related to the formation of ground state complex formation, caused by the partial adsorption of BSA on the surface of NPs. However, increased concentrations of BSA resulted in decrease in SPR intensity of gold nanoparticles (528 nm) and absorbance peak of BSA started diminishing. AuNPs acted as quencher for BSA fluorescence intensity, when excited at 280 nm. The binding constant (K) and the number of binding sites (n) between AuNPs and BSA have been found to be 1.97×10{sup 2} LM{sup −1} and 0.6 respectively. With quantum dots, conjugation resulted in enhancement of fluorescence emission of quantum dots when excited at 300 nm, which might be due to the stabilizing effect of BSA on QDs or due to energy transfer from tryptophan moieties of albumin to quantum dots. -- Highlights: • Synthesis of nanoparticles (AuNPs) and quantum dots (CdS). • Conjugation of these materials with bovine serum albumin. • Optical behavioral studies.

Dual Colorimetric and Fluorescent Authentication Based on Semiconducting Polymer Dots for Anticounterfeiting Applications.

Science.gov (United States)

Tsai, Wei-Kai; Lai, Yung-Sheng; Tseng, Po-Jung; Liao, Chia-Hsien; Chan, Yang-Hsiang

2017-09-13

Semiconducting polymer dots (Pdots) have recently emerged as a novel type of ultrabright fluorescent probes that can be widely used in analytical sensing and material science. Here, we developed a dual visual reagent based on Pdots for anticounterfeiting applications. We first designed and synthesized two types of photoswitchable Pdots by incorporating photochromic dyes with multicolor semiconducting polymers to modulate their emission intensities and wavelengths. The resulting full-color Pdot assays showed that the colorimetric and fluorescent dual-readout abilities enabled the Pdots to serve as an anticounterfeiting reagent with low background interference. We also doped these Pdots into flexible substrates and prepared these Pdots as inks for pen handwriting as well as inkjet printing. We further applied this reagent in printing paper and checks for high-security anticounterfeiting purposes. We believe that this dual-readout method based on Pdots will create a new avenue for developing new generations of anticounterfeiting technologies.

A salt water battery with high stability and charging rates made from solution processed conjugated polymers with polar side chains

KAUST Repository

Moia, Davide; Giovannitti, Alexander; Szumska, Anna A.; Schnurr, Martin; Rezasoltani, Elham; Maria, Iuliana P.; Barnes, Piers R. F.; McCulloch, Iain; Nelson, Jenny

2017-01-01

conjugated polymer backbones, allowed the films to maintain constant capacity at high charge and discharge rates (>1000 C-rate). The electrodes also show good stability during electrochemical cycling (less than 30% decrease in capacity over >1000 cycles) and an output voltage up to 1.4 V. The performance of these semiconducting polymers with polar side-chains demonstrates the potential of this material class for fast-charging, water based electrochemical energy storage devices.

Elucidation of the Structure Formation of Polymer-Conjugated Proteins in Solution and Block Copolymer Templates

Science.gov (United States)

Ferebee, Rachel L.

The broader technical objective of this work is to contribute to the development of enzyme-functionalized nanoporous membranes that can function as autonomous and target selective dynamic separators. The scientific objective of the research performed within this thesis is to elucidate the parameters that control the mixing of proteins in organic host materials and in block copolymers templates in particular. A "biomimetic" membrane system that uses enzymes to selectively neutralize targets and trigger a change in permeability of nanopores lined with a pH-responsive polymer has been fabricated and characterized. Mechanical and functional stability, as well as scalability, have been demonstrated for this system. Additional research has focused on the role of polymeric ligands on the solubility characteristics of the model protein, Bovine Serum Albumin (BSA). For this purpose BSA was conjugated with poly(ethylene glycol) (PEG) ligands of varied degree of polymerization and grafting density. Combined static and dynamic light scattering was used (in conjunction with MALDI-TOF) to determine the second virial coefficient in PBS solutions. At a given mass fraction PEG or average number of grafts, the solubility of BSA-PEG conjugates is found to increase with the degree of polymerization of conjugated PEG. This result informs the synthesis of protein-conjugate systems that are optimized for the fabrication of block copolymer blend materials with maximum protein loading. Blends of BSA-PEG conjugates and block copolymer (BCP) matrices were fabricated to evaluate the dispersion morphology and solubility limits in a model system. Electron microscopy was used to evaluate the changes in lamellar spacing with increased filling fraction of BSA-PEG conjugates.

Programmed Switching of Single Polymer Conformation on DNA Origami

DEFF Research Database (Denmark)

Krissanaprasit, Abhichart; Madsen, Mikael; Knudsen, Jakob Bach

2016-01-01

-molecule conjugated polymer. The polymer is functionalized with short single-stranded (ss) DNA strands that extend from the backbone of the polymer and serve as handles. The DNA polymer conjugate can be aligned on DNA origami in three well-defined geometries (straight line, left-turned, and right-turned pattern......) by DNA hybridization directed by single-stranded guiding strands and ssDNA tracks extending from the origami surface and polymer handle. We demonstrate switching of a conjugated organic polymer conformation between left- and right-turned conformations of the polymer on DNA origami based on toehold...

Soluble polymer conjugates for drug delivery.

Science.gov (United States)

Minko, Tamara

2005-01-01

The use of water-soluble polymeric conjugates as drug carriers offers several possible advantages. These advantages include: (1) improved drug pharmacokinetics; (2) decreased toxicity to healthy organs; (3) possible facilitation of accumulation and preferential uptake by targeted cells; (4) programmed profile of drug release. In this review, we will consider the main types of useful polymeric conjugates and their role and effectiveness as carriers in drug delivery systems.: © 2005 Elsevier Ltd . All rights reserved.

Quantum dots conjugated zinc oxide nanosheets: Impeder of microbial growth and biofilm

Science.gov (United States)

Patil, Rajendra; Gholap, Haribhau; Warule, Sambhaji; Banpurkar, Arun; Kulkarni, Gauri; Gade, Wasudeo

2015-01-01

The grieving problem of the 21st century has been the antimicrobial resistance in pathogenic microorganisms to conventional antibiotics. Therefore, developments of novel antibacterial materials which effectively inhibit or kill such resistant microorganisms have become the need of the hour. In the present study, we communicate the synthesis of quantum dots conjugated zinc oxide nanostructures (ZnO/CdTe) as an impeder of microbial growth and biofilm. The as-synthesized nanostructures were characterized by X-ray diffraction, ultraviolet-visible spectroscopy, photoluminescence spectroscopy, field emission scanning electron microscopy and high resolution transmission electron microscopy. The growth impedance property of ZnO and ZnO/CdTe on Gram positive organism, Bacillus subtilis NCIM 2063 and Gram negative, Escherichia coli NCIM 2931 and biofilm impedance activity in Pseudomonas aeruginosa O1 was found to occur due to photocatalytical action on the cell biofilm surfaces. The impedance in microbial growth and biofilm formation was further supported by ruptured appearances of cells and dettrered biofilm under field emission scanning electron and confocal laser scanning microscope. The ZnO/CdTe nanostructures array synthesized by hydrothermal method has an advantage of low growth temperature, and opportunity to fabricate inexpensive material for nano-biotechnological applications.

Interactions of a zwitterionic thiophene-based conjugated polymer with surfactants

DEFF Research Database (Denmark)

Costa, Telma; De Azevedo, Diego; Stewart, Beverly

2015-01-01

In this paper we investigate the optical and structural properties of a zwitterionic poly[3-(N-(4-sulfonato-1-butyl)-N,N-diethylammonium)hexyl-2,5-thiophene] (P3SBDEAHT) conjugated polyelectrolyte (CPE) and its interaction in water with surfactants, using absorption, photoluminescence (PL......), electrical conductivity, molecular dynamics simulations (MDS) and small-angle X-ray scattering (SAXS). Different surfactants were studied to evaluate the effect of the head group and chain length on the self-assembly. PL data emphasize the importance of polymer-surfactant electrostatic interactions...... in the formation of complexes. Nevertheless, conductivity and MDS data have shown that nonspecific interactions also play an important role. These seem to be responsible for the spatial position of the surfactant tail in the complex and, eventually, for breaking-up P3SBDEAHT aggregates. SAXS measurements on P3...

Hydrazinonicotinamide prolongs quantum dot circulation and reduces reticuloendothelial system clearance by suppressing opsonization and phagocyte engulfment

Science.gov (United States)

Jung, Kyung-Ho; Park, Jin Won; Paik, Jin-Young; Lee, Eun Jeong; Choe, Yearn Seong; Lee, Kyung-Han

2012-12-01

In this study, we investigated the effects of hydrazinonicotinamide (HYNIC)—a bifunctional crosslinker widely used to 99mTc radiolabel protein and nanoparticles for imaging studies—on quantum dot opsonization, macrophage engulfment and in vivo kinetics. In streptavidin-coated quantum dots (SA-QDots), conjugation with HYNIC increased the net negative charge without affecting the zeta potential. Confocal microscopy and fluorescence-activated cell sorting showed HYNIC attachment to suppress SA-QDot engulfment by macrophages. Furthermore, HYNIC conjugation suppressed surface opsonization by serum protein including IgG. When intravenously injected into mice, HYNIC conjugation significantly prolonged the circulation of SA-QDots and reduced their hepatosplenic uptake. Diminished reticuloendothelial system clearance of SA-QDots and aminoPEG-QDots by HYNIC conjugation was also demonstrated by in vivo and ex vivo optical imaging. The effects of HYNIC on the opsonization, phagocytosis and in vivo kinetics of quantum dots were reversed by removal of the hydrazine component from HYNIC. Thus, surface functionalization with HYNIC can improve the in vivo kinetics of quantum dots by reducing phagocytosis via suppression of surface opsonization.

Color optimization of conjugated-polymer/InGaN hybrid white light emitting diodes by incomplete energy transfer

International Nuclear Information System (INIS)

Chang, Chi-Jung; Lai, Chun-Feng; Madhusudhana Reddy, P.; Chen, Yung-Lin; Chiou, Wei-Yung; Chang, Shinn-Jen

2015-01-01

By using the wavelength conversion method, white light emitting diodes (WLEDs) were produced by applying mixtures of polysiloxane and fluorescent polymers on InGaN based light emitting diodes. UV curable organic–inorganic hybrid materials with high refractive index (1.561), compromised optical, thermal and mechanical properties was used as encapsulants. Red light emitting fluorescent FABD polymer (with 9,9-dioctylfluorene (F), anthracene (A) and 2,1,3-benzothiadiazole (B), and 4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (D) repeating units) and green light emitting fluorescent FAB polymer were used as wavelength converters. The encapsulant/fluorescent polymer mixture and InGaN produce the white light by incomplete energy transfer mechanism. WLEDs with high color rendering index (CRI, about 93), and tunable correlated color temperature (CCT) properties can be produced by controlling the composition and chemical structures of encapsulating polymer and fluorescent polymer in hybrid materials, offering cool-white and neutral-white LEDs. - Highlights: • Highly efficient white light-emitting diodes (WLEDs) were produced. • Conjugated-polymer/InGaN hybrid WLEDs by incomplete energy transfer mechanism. • WLEDs with high color-rendering index and tunable correlated color temperature. • Polysiloxane encapsulant with superior optical, mechanical and thermal properties

Solvent-resistant organic transistors and thermally stable organic photovoltaics based on cross-linkable conjugated polymers

KAUST Repository

Kim, Hyeongjun

2012-01-10

Conjugated polymers, in general, are unstable when exposed to air, solvent, or thermal treatment, and these challenges limit their practical applications. Therefore, it is of great importance to develop new materials or methodologies that can enable organic electronics with air stability, solvent resistance, and thermal stability. Herein, we have developed a simple but powerful approach to achieve solvent-resistant and thermally stable organic electronic devices with a remarkably improved air stability, by introducing an azide cross-linkable group into a conjugated polymer. To demonstrate this concept, we have synthesized polythiophene with azide groups attached to end of the alkyl chain (P3HT-azide). Photo-cross-linking of P3HT-azide copolymers dramatically improves the solvent resistance of the active layer without disrupting the molecular ordering and charge transport. This is the first demonstration of solvent-resistant organic transistors. Furthermore, the bulk-heterojunction organic photovoltaics (BHJ OPVs) containing P3HT-azide copolymers show an average efficiency higher than 3.3% after 40 h annealing at an elevated temperature of 150 °C, which represents one of the most thermally stable OPV devices reported to date. This enhanced stability is due to an in situ compatibilizer that forms at the P3HT/PCBM interface and suppresses macrophase separation. Our approach paves a way toward organic electronics with robust and stable operations. © 2011 American Chemical Society.

Semiconducting polymer dot as a highly effective contrast agent for photoacoustic imaging

Science.gov (United States)

Yuan, Zhen; Zhang, Jian

2018-02-01

In this study, we developed a novel PIID-DTBT based semiconducting polymer dots (Pdots) that have broad and strong optical absorption in the visible-light region (500 nm - 700 nm). Gold nanoparticles (GNPs) and gold nanorods (GNRs) that have been verified as an excellent photoacoustic contrast agent were compared with Pdots based on photoacoustic imaging method. Both ex vivo and in vivo experiment demonstrated Pdots have a better photoacoustic conversion efficiency at 532 nm than GNPs and similar photoacoustic performance with GNRs at 700 nm at the same mass concentration. Our work demonstrates the great potential of Pdots as a highly effective contrast agent for precise localization of lesions relative to the blood vessels based on photoacoustic tomography imaging.

Conducting polymers, buckminsterfullerenes, and carbon nanotubes: optoelectronic materials based on architectural diversity of the π-conjugated structure

International Nuclear Information System (INIS)

Dai, L.

2001-01-01

Recent discovery of superconductivity in self assembled poly(3-hexylthiophene) two-dimensional conjugated sheets indicates the possible applications of plastics even in superconducting optoelectronic devices. Just as the discovery of C 60 has created an entirely new branch of carbon chemistry, the subsequent discovery of carbon nanotubes by lijima in 1991 opened up a new era in material science and nanotechnology. These elongated nanotubes consist of carbon hexagons arranged in a concentric manner with both ends normally capped by fullerene-like structures containing pentagons. Having a conjugated all-carbon structure with unusual molecular symmetries, fullerenes and carbon nanotubes also show interesting electronic, photonic, magnetic and mechanical properties, attractive for various applications, including optical limiters, photovoltaic cells and field emitting displays. For most of the above applications, it is highly desirable to prepare ordered/micropatterned conducting polymers, fullerenes, and carbon nanotubes. Although the microfabrication of conducting polymers has been an active research area for some years, it is a very recent development for fullerenes and carbon nanotubes. Recently, we doped polyaniline (PANI) with a hydrogensulfated fullerenol derivative containing multiple -OSO 3 H groups (i.e. C 60 (OH) 6 (OSO 3 H) 6 ) to produce three-dimensional PANI conductors with a room-temperature conductivity of up to 100 S cm -1 . This value of conductivity is about six orders of magnitude higher than the typical value for C 60 doped conducting polymers. Later, in collaboration with Wan's group at the Chinese Academy of Sciences, we have also synthesized PANI nanotubes via a self assembled C 60 (OH) 6 (OSO 3 H) 6 supramolecular template using (NH 4 ) 2 S 2 O 8 as an oxidant. These results, together with the more recent discovery of a hollow sphere, self assembled by the potassium salt of pentaphenyl fullerene (Ph 5 C 60 K) in water, clearly indicate that

Identification of excited states in conjugated polymers

International Nuclear Information System (INIS)

Hartwell, Lewis John

2003-01-01

This thesis reports quasi steady state photoinduced absorption measurements from three conjugated polymers: polypyridine (PPy), polyfluorene (PFO) and the emeraldine base (EB) form of polyaniline. The aim of these experiments was to determine the nature of the photoexcited states existing in these materials in the millisecond time domain, as this has important consequences for the operation of real devices manufactured using these materials. The results from the photoinduced absorption experiments are closely compared with published results from pulse radiolysis experiments. In all cases there is very good correspondence between the two data sets, which has enabled the photoexcited states to be assigned with a high degree of confidence. Quasi steady-state photoinduced absorption involves the measurement of the change in absorption of a material in response to optical excitation with a laser beam. The changes in absorption are small, so a dedicated instrument was developed and optimised for each different sample. Lock-in techniques were used to recover the small signals from the samples. The samples involved were thin films of the polymer spin coated onto sapphire substrates in the cases of PPy and EB. Solution state experiments were conducted on EB. The experiments on PFO were conducted on aligned and unaligned thin films provided by Sony. In the case of the aligned PFO samples, the photoinduced absorption spectrometer was modified to enable polarisation-sensitive data collection. In PPy, both triplet excitons and polarons have been shown to be long-lived photoexcitations, with photoinduced absorption features at 2.29 eV (triplet exciton transition), 1.5 eV and 0.8 eV (polaron transitions). In PFO, the one observed photoinduced band at 1.52 eV is assigned to a triplet exciton. Two photoinduced absorption bands are observed in EB, at 1.4 eV and 0.8 eV. These are assigned to a self-trapped CT singlet exciton and triplet exciton, respectively. (author)

CONJUGATED BLOCK-COPOLYMERS FOR ELECTROLUMINESCENT DIODES

NARCIS (Netherlands)

Hilberer, A; Gill, R.E; Herrema, J.K; Malliaras, G.G; Wildeman, J.; Hadziioannou, G

In this article we review results obtained in our laboratory on the design and study of new light-emitting polymers. We are interested in the synthesis and characterisation of block copolymers with regularly alternating conjugated and non conjugated sequences. The blocks giving rise to luminescence

In vitro and in vivo imaging of prostate cancer angiogenesis using anti-vascular endothelial growth factor receptor 2 antibody-conjugated quantum dot

International Nuclear Information System (INIS)

Kwon, Haejin; Lee, Jiyeon; Song, Rita; Lee, Jung Han; Hwang, Sung Il; Lee, Hak Jong; Kim, Young Hwa

2013-01-01

Authors aimed to determine the targeting ability of vascular endothelial growth factor receptor 2 (VEGFR2)-conjugated quantum dots (QDs) in vitro, and apply it for a xenograft prostate cancer mouse model. Conjugation reaction of QDs was performed by using the N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and sulfo-(N-hydroxysulfosuccinimide) (Sulfo-NHS). The human umbilical vein cord endothelial cells (HUVECs) were incubated with QDs, conjugated with antiVGFR2, to see a specific binding in vitro. Fluorescent cell images were taken by a confocal microscope. The human prostate cancer cells (PC3) were injected to five nude mice on hind limbs to make the xenograft tumor model. QD-antiVEGFR2 antibody complex was injected into the tumor model and fluorescence measurements were performed at 1, 4, 9, 12, 15, and 24 hours after the injection. The specific interaction between HUVECs and QD-antiVEGFR2 antibody was clearly shown in vitro. The in vivo fluorescence image disclosed that there was an increased signal of tumor, 12 hours after the injection of QDs. By showing endothelial cells binding with QDs-antiVEGFR2 antibodyand an experimental application of the antibody for VEGFR2 imaging in the prostate cancer xenograft mouse model, we suggests that the antibody-conjugated QDs can be a potential imaging tool for angiogenesis of the cancer.

A salt water battery with high stability and charging rates made from solution processed conjugated polymers with polar side chains

KAUST Repository

Moia, Davide

2017-11-28

We report a neutral salt water based battery which uses p-type and n-type solution processed polymer films as the cathode and the anode of the cell. The specific capacity of the electrodes (approximately 30 mAh cm-3) is achieved via formation of bipolarons in both the p-type and n-type polymers. By engineering ethylene glycol and zwitterion based side chains attached to the polymer backbone we facilitate rapid ion transport through the non-porous polymer films. This, combined with efficient transport of electronic charge via the conjugated polymer backbones, allowed the films to maintain constant capacity at high charge and discharge rates (>1000 C-rate). The electrodes also show good stability during electrochemical cycling (less than 30% decrease in capacity over >1000 cycles) and an output voltage up to 1.4 V. The performance of these semiconducting polymers with polar side-chains demonstrates the potential of this material class for fast-charging, water based electrochemical energy storage devices.

Roll-to-Roll printed large-area all-polymer solar cells with 5% efficiency based on a low crystallinity conjugated polymer blend

Science.gov (United States)

Gu, Xiaodan; Zhou, Yan; Gu, Kevin; Kurosawa, Tadanori; Yan, Hongping; Wang, Cheng; Toney, Micheal; Bao, Zhenan

The challenge of continuous printing in high efficiency large-area organic solar cells is a key limiting factor for their widespread adoption. We present a materials design concept for achieving large-area, solution coated all-polymer bulk heterojunction (BHJ) solar cells with stable phase separation morphology between the donor and acceptor. The key concept lies in inhibiting strong crystallization of donor and acceptor polymers, thus forming intermixed, low crystallinity and mostly amorphous blends. Based on experiments using donors and acceptors with different degree of crystallinity, our results showed that microphase separated donor and acceptor domain sizes are inversely proportional to the crystallinity of the conjugated polymers. This methodology of using low crystallinity donors and acceptors has the added benefit of forming a consistent and robust morphology that is insensitive to different processing conditions, allowing one to easily scale up the printing process from a small scale solution shearing coater to a large-scale continuous roll-to-roll (R2R) printer. We were able to continuously roll-to-roll slot die print large area all-polymer solar cells with power conversion efficiencies of 5%, with combined cell area up to 10 cm2. This is among the highest efficiencies realized with R2R coated active layer organic materials on flexible substrate. DOE BRIDGE sunshot program. Office of Naval Research.

Graphene quantum dots-three-dimensional graphene composites for high-performance supercapacitors.

Science.gov (United States)

Chen, Qing; Hu, Yue; Hu, Chuangang; Cheng, Huhu; Zhang, Zhipan; Shao, Huibo; Qu, Liangti

2014-09-28

Graphene quantum dots (GQDs) have been successfully deposited onto the three-dimensional graphene (3DG) by a benign electrochemical method and the ordered 3DG structure remains intact after the uniform deposition of GQDs. In addition, the capacitive properties of the as-formed GQD-3DG composites are evaluated in symmetrical supercapacitors. It is found that the supercapacitor fabricated from the GQD-3DG composite is highly stable and exhibits a high specific capacitance of 268 F g(-1), representing a more than 90% improvement over that of the supercapacitor made from pure 3DG electrodes (136 F g(-1)). Owing to the convenience of the current method, it can be further used in other well-defined electrode materials, such as carbon nanotubes, carbon aerogels and conjugated polymers to improve the performance of the supercapacitors.

Conducting Polymers for Neutron Detection

International Nuclear Information System (INIS)

Clare Kimblin; Kirk Miller; Bob Vogel; Bill Quam; Harry McHugh; Glen Anthony; Steve Jones; Mike Grover

2007-01-01

Conjugated polymers have emerged as an attractive technology for large-area electronic applications. As organic semiconductors, they can be used to make large-area arrays of diodes or transistors using fabrication techniques developed for polymer coatings, such as spraying and screen-printing. We have demonstrated both neutron and alpha detection using diodes made from conjugated polymers and have done preliminary work to integrate a boron carbide layer into the conventional polymer device structure to capture thermal neutrons. The polymer devices appear to be insensitive to gamma rays, due to their small physical thickness and low atomic number

Light-Induced Fluorescence Modulation of Quantum Dot-Crystal Violet Conjugates: Stochastic Off-On-Off Cycles for Multicolor Patterning and Super-Resolution.

Science.gov (United States)

Jung, Sungwook; Park, Joonhyuck; Bang, Jiwon; Kim, Jae-Yeol; Kim, Cheolhee; Jeon, Yongmoon; Lee, Seung Hwan; Jin, Ho; Choi, Sukyung; Kim, Bomi; Lee, Woo Jin; Pack, Chan-Gi; Lee, Jong-Bong; Lee, Nam Ki; Kim, Sungjee

2017-06-07

Photoswitching or modulation of quantum dots (QDs) can be promising for many fields that include display, memory, and super-resolution imaging. However, such modulations have mostly relied on photomodulations of conjugated molecules in QD vicinity, which typically require high power of high energy photons at UV. We report a visible light-induced facile modulation route for QD-dye conjugates. QD crystal violets conjugates (QD-CVs) were prepared and the crystal violet (CV) molecules on QD quenched the fluorescence efficiently. The fluorescence of QD-CVs showed a single cycle of emission burst as they go through three stages of (i) initially quenched "off" to (ii) photoactivated "on" as the result of chemical change of CVs induced by photoelectrons from QD and (iii) back to photodarkened "off" by radical-associated reactions. Multicolor on-demand photopatterning was demonstrated using QD-CV solid films. QD-CVs were introduced into cells, and excitation with visible light yielded photomodulation from "off" to "on" and "off" by nearly ten fold. Individual photoluminescence dynamics of QD-CVs was investigated using fluorescence correlation spectroscopy and single QD emission analysis, which revealed temporally stochastic photoactivations and photodarkenings. Exploiting the stochastic fluorescence burst of QD-CVs, simultaneous multicolor super-resolution localizations were demonstrated.

Charge transport in conjugated polymer-semiconductor nanoparticle composite near the percolation threshold

Science.gov (United States)

Cardoso, L. S.; Gonçalves, G. E.; Kanda, D. H. F.; Bianchi, R. F.; Nagashima, H. N.

2017-12-01

This paper describes a new statistical model to predict the frequency dependence of the conductivity of conjugated polymer-semiconductor nanoparticle composites. The model considers AC conduction in an inhomogeneous medium represented by a two-dimensional model of resistor network. The conductivity between two neighboring sites in the polymer matrix and the semiconductor particles is assumed to obey the random free energy barrier model and the Drude model, respectively. The real and imaginary parts of the AC conductivity were determined using the transfer-matrix technique, and the statistical model was applied to experimental data of thin films composed of polyaniline (PANI) and indium-tin-oxide (ITO) nanoparticles. The conductivity critical exponent ( s) obtained in two dimensions for PANI/ITO films below the percolation threshold was found to be 2.7, which is greater than the universal value of s described by the classical percolation theory ( s = 1.3). This non-universality is explained by the existence of a local electric field distribution in the bulk of the nanocomposite. Finally, these results are discussed in terms of the distribution of potential barriers that vary according to the concentration of ITO amount in the composite.

High transmittance optical films based on quantum dot doped nanoscale polymer dispersed liquid crystals

Science.gov (United States)

Gandhi, Sahil Sandesh; Chien, Liang-Chy

2016-04-01

We propose a simple way to fabricate highly transparent nanoscale polymer dispersed liquid crystal (nano-PDLC) films between glass substrates and investigate their incident angle dependent optical transmittance properties with both collimated and Lambertian intensity distribution light sources. We also demonstrate that doping nano-PDLC films with 0.1% InP/ZnS core/shell quantum dots (QD) results in a higher optical transmittance. This work lays the foundation for such nanostructured composites to potentially serve as roll-to-roll coatable light extraction or brightness enhancement films in emissive display applications, superior to complex nanocorrugation techniques proposed in the past.

Characterization of electrosynthesized conjugated polymer-carbon nanotube composite: optical nonlinearity and electrical property.

Science.gov (United States)

Bahrami, Afarin; Talib, Zainal Abidin; Shahriari, Esmaeil; Yunus, Wan Mahmood Mat; Kasim, Anuar; Behzad, Kasra

2012-01-01

The effects of multi-walled carbon nanotube (MWNT) concentration on the structural, optical and electrical properties of conjugated polymer-carbon nanotube composite are discussed. Multi-walled carbon nanotube-polypyrrole nanocomposites were synthesized by electrochemical polymerization of monomers in the presence of different amounts of MWNTs using sodium dodecylbenzensulfonate (SDBS) as surfactant at room temperature and normal pressure. Field emission scanning electron microscopy (FESEM) indicates that the polymer is wrapped around the nanotubes. Measurement of the nonlinear refractive indices (n(2)) and the nonlinear absorption (β) of the samples with different MWNT concentrations measurements were performed by a single Z-scan method using continuous wave (CW) laser beam excitation wavelength of λ = 532 nm. The results show that both nonlinear optical parameters increased with increasing the concentration of MWNTs. The third order nonlinear susceptibilities were also calculated and found to follow the same trend as n(2) and β. In addition, the conductivity of the composite film was found to increase rapidly with the increase in the MWNT concentration.

Indolo-naphthyridine-6,13-dione Thiophene Building Block for Conjugated Polymer Electronics: Molecular Origin of Ultrahigh n-Type Mobility

KAUST Repository

Fallon, Kealan J.

2016-10-18

Herein, we present the synthesis and characterization of four conjugated polymers containing a novel chromophore for organic electronics based on an indigoid structure. These polymers exhibit extremely small band gaps of ∼1.2 eV, impressive crystallinity, and extremely high n-type mobility exceeding 3 cm V s. The n-type charge carrier mobility can be correlated with the remarkably high crystallinity along the polymer backbone having a correlation length in excess of 20 nm. Theoretical analysis reveals that the novel polymers have highly rigid nonplanar geometries demonstrating that backbone planarity is not a prerequisite for either narrow band gap materials or ultrahigh mobilities. Furthermore, the variation in backbone crystallinity is dependent on the choice of comonomer. OPV device efficiencies up to 4.1% and charge photogeneration up to 1000 nm are demonstrated, highlighting the potential of this novel chromophore class in high-performance organic electronics.

Indolo-naphthyridine-6,13-dione Thiophene Building Block for Conjugated Polymer Electronics: Molecular Origin of Ultrahigh n-Type Mobility

KAUST Repository

Fallon, Kealan J.; Wijeyasinghe, Nilushi; Manley, Eric F.; Dimitrov, Stoichko D.; Yousaf, Syeda A.; Ashraf, Raja S.; Duffy, Warren; Guilbert, Anne A. Y.; Freeman, David M. E.; Al-Hashimi, Mohammed; Nelson, Jenny; Durrant, James R.; Chen, Lin X.; McCulloch, Iain; Marks, Tobin J.; Clarke, Tracey M.; Anthopoulos, Thomas D.; Bronstein, Hugo

2016-01-01

Herein, we present the synthesis and characterization of four conjugated polymers containing a novel chromophore for organic electronics based on an indigoid structure. These polymers exhibit extremely small band gaps of ∼1.2 eV, impressive crystallinity, and extremely high n-type mobility exceeding 3 cm V s. The n-type charge carrier mobility can be correlated with the remarkably high crystallinity along the polymer backbone having a correlation length in excess of 20 nm. Theoretical analysis reveals that the novel polymers have highly rigid nonplanar geometries demonstrating that backbone planarity is not a prerequisite for either narrow band gap materials or ultrahigh mobilities. Furthermore, the variation in backbone crystallinity is dependent on the choice of comonomer. OPV device efficiencies up to 4.1% and charge photogeneration up to 1000 nm are demonstrated, highlighting the potential of this novel chromophore class in high-performance organic electronics.

The role of polymer dots on efficiency enhancement of organic solar cells: Improving charge transport property

Science.gov (United States)

Li, Jinfeng; Zhang, Xinyuan; Liu, Chunyu; Li, Zhiqi; He, Yeyuan; Zhang, Zhihui; Shen, Liang; Guo, Wenbin; Ruan, Shengping

2017-07-01

In this work, poly(9,9-dioctylfluorene)-co-(4,7-di-2-thienyl-2,1,3-benzothiadiazole) (PF-5DTBT) and copolymer poly(styrene-co-maleic anhydride) (PSMA) dots were prepared as additive for active layer doping to enhance the power conversion efficiency (PCE) of organic solar cells (OSCs), which based on poly[N-9″-hepta-decanyl-2,7-carbazole-alt-5,5-(4‧,7‧-di-2-thienyl-2‧,1‧,3‧-benzothiadiazole) (PCDTBT) and [6,6]-phenyl C71 butyric acid methyl-ester (PC71BM). A high efficiency of 7.40% was achieved due to increase of short-circuit current (Jsc) and fill factor (FF). The operation mechanism of OSCs doping with polymer dots was investigated, which demonstrated that the efficiency enhancement ascribes to improvement of electrical properties, such as exciton generation, exction dissociation, charge transport, and charge collection.

Seeded emulsion polymerization as a powerful tool for the biofunctionalization of quantum dots

Energy Technology Data Exchange (ETDEWEB)

Habercorn, Lasse; Merkl, Jan-Philip; Kloust, Hauke Christian; Feld, Artur; Schmidtke, Christian; Wolter, Christopher; Janschel, Marcus [Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg (Germany); Ostermann, Johannes [Center for Applied Nanotechnology GmbH, Grindelallee 117, 20146 Hamburg (Germany); Weller, Horst [Institute of Physical Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg (Germany); Center for Applied Nanotechnology GmbH, Grindelallee 117, 20146 Hamburg (Germany)

2016-05-18

With the polymer encapsulation of quantum dots via seeded emulsion polymerization we present a powerful tool for the preparation of fluorescent nanoparticles with an extraordinary stability in aqueous solution. The method of the seeded emulsion polymerization allows a straightforward and simple in situ functionalization of the polymer shell under preserving the optical properties of the quantum dots. These requirements are inevitable for the application of semiconductor nanoparticles as markers for biomedical applications. Polymer encapsulated quantum dots have shown only a marginal loss of quantum yields when they were exposed to copper(II)-ions. Under normal conditions the quantum dots were totally quenched in presence of copper(II)-ions. Furthermore, a broad range of in situ functionalized polymer-coated quantum dots were obtained by addition of functional monomers or surfactants like fluorescent dye molecules, antibodies or specific DNA aptamers. Furthermore the emulsion polymerization can be used to prepare multifunctional hybrid systems, combining different nanoparticles within one construct without any adverse effect of the properties of the starting materials.{sup 1,2}.

Seeded emulsion polymerization as a powerful tool for the biofunctionalization of quantum dots

International Nuclear Information System (INIS)

Habercorn, Lasse; Merkl, Jan-Philip; Kloust, Hauke Christian; Feld, Artur; Schmidtke, Christian; Wolter, Christopher; Janschel, Marcus; Ostermann, Johannes; Weller, Horst

2016-01-01

With the polymer encapsulation of quantum dots via seeded emulsion polymerization we present a powerful tool for the preparation of fluorescent nanoparticles with an extraordinary stability in aqueous solution. The method of the seeded emulsion polymerization allows a straightforward and simple in situ functionalization of the polymer shell under preserving the optical properties of the quantum dots. These requirements are inevitable for the application of semiconductor nanoparticles as markers for biomedical applications. Polymer encapsulated quantum dots have shown only a marginal loss of quantum yields when they were exposed to copper(II)-ions. Under normal conditions the quantum dots were totally quenched in presence of copper(II)-ions. Furthermore, a broad range of in situ functionalized polymer-coated quantum dots were obtained by addition of functional monomers or surfactants like fluorescent dye molecules, antibodies or specific DNA aptamers. Furthermore the emulsion polymerization can be used to prepare multifunctional hybrid systems, combining different nanoparticles within one construct without any adverse effect of the properties of the starting materials."1","2

Nucleoside conjugates of quantum dots for characterization of G protein-coupled receptors: strategies for immobilizing A2A adenosine receptor agonists

Directory of Open Access Journals (Sweden)

Gao Zhan-Guo

2010-05-01

Full Text Available Abstract Background Quantum dots (QDs are crystalline nanoparticles that are compatible with biological systems to provide a chemically and photochemically stable fluorescent label. New ligand probes with fluorescent reporter groups are needed for detection and characterization of G protein-coupled receptors (GPCRs. Results Synthetic strategies for coupling the A2A adenosine receptor (AR agonist CGS21680 (2-[4-(2-carboxyethylphenylethylamino]-5'-N-ethylcarboxamidoadenosine to functionalized QDs were explored. Conjugates tethered through amide-linked chains and poly(ethyleneglycol (PEG displayed low solubility and lacked receptor affinity. The anchor to the dendron was either through two thiol groups of (R-thioctic acid or through amide formation to a commercial carboxy-derivatized QD. The most effective approach was to use polyamidoamine (PAMAM D5 dendrons as multivalent spacer groups, grafted on the QD surface through a thioctic acid moiety. In radioligand binding assays, dendron nucleoside conjugate 11 displayed a moderate affinity at the human A2AAR (Kiapp 1.02 ± 0.15 μM. The QD conjugate of increased water solubility 13, resulting from the anchoring of this dendron derivative, interacted with the receptor with Kiapp of 118 ± 54 nM. The fluorescence emission of 13 occurred at 565 nm, and the presence of the pendant nucleoside did not appreciably quench the fluorescence. Conclusions This is a feasibility study to demonstrate a means of conjugating to a QD a small molecular pharmacophore of a GPCR that is relatively hydrophobic. Further enhancement of affinity by altering the pharmacophore or the linking structures will be needed to make useful affinity probes.

Preparation, Single-Molecule Manipulation, and Energy Transfer Investigation of a Polyfluorene-graft-DNA polymer.

Science.gov (United States)

Madsen, Mikael; Christensen, Rasmus S; Krissanaprasit, Abhichart; Bakke, Mette R; Riber, Camilla F; Nielsen, Karina S; Zelikin, Alexander N; Gothelf, Kurt V

2017-08-04

Conjugated polymers have been intensively studied due to their unique optical and electronic properties combined with their physical flexibility and scalable bottom up synthesis. Although the bulk qualities of conjugated polymers have been extensively utilized in research and industry, the ability to handle and manipulate conjugated polymers at the nanoscale lacks significantly behind. Here, the toolbox for controlled manipulation of conjugated polymers was expanded through the synthesis of a polyfluorene-DNA graft-type polymer (poly(F-DNA)). The polymer possesses the characteristics associated with the conjugated polyfluorene backbone, but the protruding single-stranded DNA provides the material with an exceptional addressability. This study demonstrates controlled single-molecule patterning of poly(F-DNA), as well as energy transfer between two different polymer-DNA conjugates. Finally, highly efficient DNA-directed quenching of polyfluorene fluorescence was shown. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interpenetrating networks of two conducting polymers

DEFF Research Database (Denmark)

Winther-Jensen, Bjørn; West, Keld

2005-01-01

Interpenetrating networks (IPNs) of two conjugated polymers are prepared by a combination of a chemical oxidation step and a vapour phase polymerisation step on non-conducting surfaces. In this work ferric tosylate was used as the oxidant as it gives very smooth and homogeneous coatings, and beca......Interpenetrating networks (IPNs) of two conjugated polymers are prepared by a combination of a chemical oxidation step and a vapour phase polymerisation step on non-conducting surfaces. In this work ferric tosylate was used as the oxidant as it gives very smooth and homogeneous coatings......, and because its reaction products can be removed efficiently after the formation of the composite. Several combinations of polymers are demonstrated, and the versatility of the proposed method allows extensions to a wide range of conjugated polymers. The IPNs show optical and electrochemical characteristics......, which are sums of the characteristics from the participating conducting polymers....

HYDROGELS BASED ON POLYMERS OF DEXTRAN TYRAMINE AND TYRAMINE CONJUGATES OF NATURAL POLYMERS

NARCIS (Netherlands)

Feijen, Jan; Karperien, Marcel; Jin, R.; Moreira Teixeira, Liliana; Dijkstra, Pieter J.

2012-01-01

The invention relates to composition comprising a dextran-tyramine conjugate and a conjugate selected from the group consisting of chondroitin sulphate-tyramine, collagen-tyramine, chitosan-tyramine, chitosan-phloretic acid, gelatine-tyramine, heparan sulphate-tyramine, keratin sulphate-tyramine,

HYDROGELS BASED ON POLYMERS OF DEXTRAN TYRAMINE AND TYRAMINE CONJUGATES OF NATURAL POLYMERS

NARCIS (Netherlands)

Karperien, H.B.J.; Jin, R.; Moreira Teixeira, Liliana; Feijen, Jan; Dijkstra, Pieter J.

2011-01-01

The invention relates to composition comprising a dextran-tyramine conjugate and a conjugate selected from the group consisting of chondroitin sulphate-tyramine, collagen-tyramine, chitosan-tyramine, chitosan-phloretic acid, gelatine-tyramine, heparan sulphate-tyramine, keratin sulphate tyramine,

Synthesis and Properties of 1,8-Carbazole-Based Conjugated Copolymers

Directory of Open Access Journals (Sweden)

Tsuyoshi Michinobu

2010-07-01

Full Text Available A new series of conjugated carbazole polymers based on the 1,8-carbazolylene unit was synthesized by the Pd-catalyzed polycondensation between the 1,8-diiodocarbazole derivative and various bifunctional counter comonomers. An alkyne spacer was found to be a key to increasing the molecular weight of the resulting polymers. All the obtained polymers showed good solubilities in the common organic solvents, and they were fully characterized by Gel permeation chromatography (GPC, and 1H NMR and infrared (IR spectroscopies. The UV-vis absorption and fluorescence spectra revealed the relationship between the chemical structure and effective conjugation length. The efficiency order of the carbazole connectivity was 2,7-carbazolylene > 1,8-carbazolylene > 3,6-carbazolylene. The electrochemical properties of these polymers suggested the relatively facile oxidation at ca. +0.5–0.7 V vs. Fc/Fc+ or a high potential as p-type semiconductors. The combination of the electrochemical oxidation potentials and the optical band gaps allowed us to estimate the HOMO and LUMO levels of the polymers. It was shown that the energy levels of the 1,8-carbazole-based conjugated polymers can be tunable by selecting the appropriate comonomer structures.

A sensitive fluorescent nanosensor for chloramphenicol based on molecularly imprinted polymer-capped CdTe quantum dots.

Science.gov (United States)

Amjadi, Mohammad; Jalili, Roghayeh; Manzoori, Jamshid L

2016-05-01

A novel fluorescent nanosensor using molecularly imprinted silica nanospheres embedded CdTe quantum dots (CdTe@SiO2 @MIP) was developed for detection and quantification of chloramphenicol (CAP). The imprinted sensor was prepared by synthesis of molecularly imprinting polymer (MIP) on the hydrophilic CdTe quantum dots via reverse microemulsion method using small amounts of solvents. The resulting CdTe@SiO2 @MIP nanoparticles were characterized by fluorescence, UV-vis absorption and FT-IR spectroscopy and transmission electron microscopy. They preserved 48% of fluorescence quantum yield of the parent quantum dots. CAP remarkably quenched the fluorescence of prepared CdTe@SiO2 @MIP, probably via electron transfer mechanism. Under the optimal conditions, the relative fluorescence intensity of CdTe@SiO2 @MIP decreased with increasing CAP by a Stern-Volmer type equation in the concentration range of 40-500 µg L(-1). The corresponding detection limit was 5.0 µg L(-1). The intra-day and inter-day values for the precision of the proposed method were all <4%. The developed sensor had a good selectivity and was applied to determine CAP in spiked human and bovine serum and milk samples with satisfactory results. Copyright © 2015 John Wiley & Sons, Ltd.

Solvent-Free Patterning of Colloidal Quantum Dot Films Utilizing Shape Memory Polymers

Directory of Open Access Journals (Sweden)

Hohyun Keum

2017-01-01

Full Text Available Colloidal quantum dots (QDs with properties that can be tuned by size, shape, and composition are promising for the next generation of photonic and electronic devices. However, utilization of these materials in such devices is hindered by the limited compatibility of established semiconductor processing techniques. In this context, patterning of QD films formed from colloidal solutions is a critical challenge and alternative methods are currently being developed for the broader adoption of colloidal QDs in functional devices. Here, we present a solvent-free approach to patterning QD films by utilizing a shape memory polymer (SMP. The high pull-off force of the SMP below glass transition temperature (Tg in conjunction with the conformal contact at elevated temperatures (above Tg enables large-area, rate-independent, fine patterning while preserving desired properties of QDs.

Highly efficient inverted polymer solar cells based on a cross-linkable water-/alcohol-soluble conjugated polymer interlayer.

Science.gov (United States)

Zhang, Kai; Zhong, Chengmei; Liu, Shengjian; Mu, Cheng; Li, Zhengke; Yan, He; Huang, Fei; Cao, Yong

2014-07-09

A cross-linkable water/alcohol soluble conjugated polymer (WSCP) material poly[9,9-bis(6'-(N,N-diethylamino)propyl)-fluorene-alt-9,9-bis(3-ethyl(oxetane-3-ethyloxy)-hexyl) fluorene] (PFN-OX) was designed. The cross-linkable nature of PFN-OX is good for fabricating inverted polymer solar cells (PSCs) with well-defined interface and investigating the detailed working mechanism of high-efficiency inverted PSCs based on poly[4,8-bis(2-ethylhexyloxyl)benzo[1,2-b:4,5-b']dithio-phene-2,6-diyl-alt-ethylhexyl-3-fluorothithieno[3,4-b]thiophene-2-carboxylate-4,6-diyl] (PTB7) and (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) blend active layer. The detailed working mechanism of WSCP materials in high-efficiency PSCs were studied and can be summarized into the following three effects: a) PFN-OX tunes cathode work function to enhance open-circuit voltage (Voc); b) PFN-OX dopes PC71BM at interface to facilitate electron extraction; and c) PFN-OX extracts electrons and blocks holes to enhance fill factor (FF). On the basis of this understanding, the hole-blocking function of the PFN-OX interlayer was further improved with addition of a ZnO layer between ITO and PFN-OX, which led to inverted PSCs with a power conversion efficiency of 9.28% and fill factor high up to 74.4%.

Indaceno-Based Conjugated Polymers for Polymer Solar Cells.

Science.gov (United States)

Yin, Yuli; Zhang, Yong; Zhao, Liancheng

2018-01-04

Polymer solar cells have received considerable attention due to the advantages of low material cost, tunable band gaps, ultralight weight, and high flexible properties, and they have been a promising organic photovoltaic technology for alternative non-renewable fossil fuels for the past decade. Inspired by these merits, numerous state-of-the-art organic photovoltaic materials have been constructed. Among them, indaceno-based polymer materials have made an impact in obtaining an impressive power conversion efficiency of more than 11%, which shows the momentous potential of this class of materials for commercial applications. In this review, recent progress of indaceno-based organic polymer solar cells are reviewed, and the structure-property device performance correlations of the reported materials are highlighted. Then, common regularities of these successful cases are collected, and encouraging viewpoints on the further development of more exciting indaceno-based organic photovoltaic materials are provided. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electroluminescent Cu-doped CdS quantum dots

NARCIS (Netherlands)

Stouwdam, J.W.; Janssen, R.A.J.

2009-01-01

Incorporating Cu-doped CdS quantum dots into a polymer host produces efficient light-emitting diodes. The Cu dopant creates a trap level that aligns with the valence band of the host, enabling the direct injection of holes into the quantum dots, which act as emitters. At low current densities, the

Comparison of the Photovoltaic Characteristics and Nanostructure of Fullerenes Blended with Conjugated Polymers with Siloxane-Terminated and Branched Aliphatic Side Chains

KAUST Repository

Kim, Do Hwan

2013-02-12

All-organic bulk heterojunction solar cells based on blends of conjugated polymers with fullerenes have recently surpassed the 8% efficiency mark and are well on their way to the industrially relevant ∼15% threshold. Using a low band-gap conjugated polymer, we have recently shown that polymer side chain engineering can lead to dramatic improvement in the in-plane charge carrier mobility. In this article, we investigate the effectiveness of siloxy side chain derivatization in controlling the photovoltaic performance of polymer:[6,6]-phenyl-C[71]-butyric acid methyl ester (PC71BM) blends and hence its influence on charge transport in the out-of-plane direction relevant for organic solar cells. We find that, in neat blends, the photocurrent of the polymer with siloxy side chains (PII2T-Si) is 4 times greater than that in blends using the polymer with branched aliphatic side chains (PII2T-ref). This difference is due to a larger out-of-plane hole mobility for PII2T-Si brought about by a largely face-on crystallite orientation as well as more optimal nanoscale polymer:PC71BM mixing. However, upon incorporating a common processing additive, 1,8-diiodooctane (DIO), into the spin-casting blend solution and following optimization, the PII2T-ref:PC71BM OPV device performance undergoes a large improvement and becomes the better-performing device, almost independent of DIO concentration (>1%). We find that the precise amount of DIO plays a larger role in determining the efficiency of PII2T-Si:PC71BM, and even at its maximum, the device performance lags behind optimized PII2T-ref:PC71BM blends. Using a combination of atomic force microscopy and small- and wide-angle X-ray scattering, we are able to elucidate the morphological modifications associated with the DIO-induced changes in both the nanoscale morphology and the molecular packing in blend films. © 2012 American Chemical Society.

Direct Photopatterning of Electrochromic Polymers

DEFF Research Database (Denmark)

Jensen, Jacob; Dyer, Aubrey L.; Shen, D. Eric

2013-01-01

Propylenedioxythiophene (ProDOT) polymers are synthesized using an oxidative polymerization route that results in methacrylate substituted poly(ProDOTs) having a Mn of 10–20 kDa wherein the methacrylate functionality constitutes from 6 to 60% of the total monomer units. Solutions of these polymers...... show excellent film forming abilities, with thin films prepared using both spray‐casting and spin‐coating. These polymers are demonstrated to crosslink upon UV irradiation at 350 nm, in the presence of an appropriate photoinitiator, to render the films insoluble to common organic solvents....... Electrochemical, spectroelectrochemical, and colorimetric analyses of the crosslinked polymer films are performed to establish that they retain the same electrochromic qualities as the parent polymers with no detriment to the observed properties. To demonstrate applicability for multi‐film processing...

Epitope imprinted polymer nanoparticles containing fluorescent quantum dots for specific recognition of human serum albumin

International Nuclear Information System (INIS)

Wang, Yi-Zhi; Li, Dong-Yan; He, Xi-Wen; Li, Wen-You; Zhang, Yu-Kui

2015-01-01

Epitope imprinted polymer nanoparticles (EI-NPs) were prepared by one-pot polymerization of N-isopropylacrylamide in the presence of CdTe quantum dots and an epitope (consisting of amino acids 598 to 609) of human serum albumin (HSA). The resulting EI-NPs exhibit specific recognition ability and enable direct fluorescence quantification of HSA based on a fluorescence turn-on mode. The polymer was characterized by FT-IR, X-ray photoelectron spectroscopy, transmission electron microscopy and dynamic light scattering. The linear calibration graph was obtained in the range of 0.25–5 μmol · mL −1 with the detection limit of 44.3 nmol · mL −1 . The EI-NPs were successfully applied to the direct fluorometric quantification of HSA in samples of human serum. Overall, this approach provides a promising tool to design functional fluorescent materials with protein recognition capability and specific applications in proteomics. (author)

Structural Modifications and Photophysical Studies of Fluorescent Conjugated Polymers for Solid State Sensor Development

Science.gov (United States)

Chen, Anting

Fluorescent conjugated polymers (FCPs) represent an exciting area of research in chemosensors and biosensors. Previously, the polymer tmeda-PPETE, N,N,N'-trimethylethylenediamino (tmeda) receptors on a poly[2,5-thiophenediyl-1,2-ethynediyl-1,4-phenylenediyl-1,2-ethynediyl] (PPETE) backbone, showed significant quenching when copper(II) was added. Tmeda-PPETE polymer preloaded with copper(II) was found to be a fluorescent "turn-on" sensor for iron cations. Additional investigation of this metallopolymer revealed a selective sensory system toward carbonate and phosphorus anions through a competitive binding of copper(II) between the polymer tmeda-PPETE and the anions. Fluorescent turn-on response under systematically varied pH was affected by the equilibrium shift of the ionization of polyprotic ions. A sterically hindered pentiptycene group was introduced to the PPETE polymer backbone aiming to reduce aggregation and self-quenching in the solid state. A new FCP, tmeda-PPpETE (poly[(pentiptycene ethynylene)-alt-(thienylene ethynylene)] with tmeda receptors, has been designed and synthesized via Sonogashira cross-coupling reaction. Absorption and emission spectra of tmeda-PPpETE showed blue shifting from tmeda-PPETE, suggesting increased rigidity of polymer backbone. Tmeda-PPpETE showed a high selectivity towards copper(II) with improved sensitivity compared to tmeda-PPETE. The fluorescent quenching response is over 120-fold at emission maximum, and the detection limit is 1.04 ppb, significantly lower than the EPA action level of 1.3 ppm for copper(II). A small turn-off fluorescent response of tmeda-PPpETE was also observed upon addition of iron cations. To further investigate the interaction between pentiptycene containing polymers and iron cations, tmpda-PPpETE containing N,N,N'-trimethylpropylenediamino (tmpda) receptors was designed and synthesized. The absorption and emission spectra for tmpda-PPpETE were analogous to those of tmeda-PPpETE, with a higher quantum

Glutathione responsive micelles incorporated with semiconducting polymer dots and doxorubicin for cancer photothermal-chemotherapy

Science.gov (United States)

Cai, Zhixiong; Zhang, Da; Lin, Xinyi; Chen, Yunzhu; Wu, Ming; Wei, Zuwu; Zhang, Zhenxi; Liu, Xiaolong; Yao, Cuiping

2017-10-01

Nanoplatform integrated with photothermal therapy (PTT) and chemotherapy has been recognized a promising agent for enhancing cancer therapeutic outcomes, but still suffer from less controllability for optimizing their synergistic effects. We fabricated glutathione (GSH) responsive micelles incorporated with semiconducting polymer dots and doxorubicin (referred as SPDOX NPs) for combining PTT with chemotherapy to enhance cancer therapeutic efficiency. These micelles, with excellent water dispersibility, comprises of three distinct functional components: (1) the monomethoxy-poly(ethylene glycol)-S-S-hexadecyl (mPEG-S-S-C16), which forms the micelles, can render hydrophobic substances water-soluble and improve the colloidal stability; (2) disulfide linkages can be cleaved in a reductive environment for tumor specific drug release due to the high GSH concentrations of tumor micro-environment; (3) PCPDTBT dots and anti-cancer drug DOX that are loaded inside the hydrophobic core of the micelle can be applied to simultaneously perform PTT and chemotherapy to achieve significantly enhanced tumor killing efficiency both in vitro and in vivo. In summary, our studies demonstrated that our SPDOX NPs with simultaneous photothermal-chemotherapy functions could be a promising platform for a tumor specific responsive drug delivery system.

Effects of polarons on static polarizabilities and second order hyperpolarizabilities of conjugated polymers

International Nuclear Information System (INIS)

Wang Ya-Dong; Meng Yan; Di Bing; Wang Shu-Ling; An Zhong

2010-01-01

According to the one-dimensional tight-binding Su—Schrieffer—Heeger model, we have investigated the effects of charged polarons on the static polarizability, α xx , and the second order hyperpolarizabilities, γ xxxx , of conjugated polymers. Our results are consistent qualitatively with previous ab initio and semi-empirical calculations. The origin of the universal growth is discussed using a local-view formalism that is based on the local atomic charge derivatives. Furthermore, combining the Su-Schrieffer-Heeger model and the extended Hubbard model, we have investigated systematically the effects of electron-electron interactions on α xx and γ xxxx of charged polymer chains. For a fixed value of the nearest-neighbour interaction V, the values of α xx and γ xxxx increase as the on-site Coulomb interaction U increases for U c and decrease with U for U > U c , where U c is a critical value of U at which the static polarizability or the second order hyperpolarizability reaches a maximal value of α max or γ max . It is found that the effect of the e-e interaction on the value of α xx is dependent on the ratio between U and V for either a short or a long charged polymer. Whereas, that effect on the value of γ xxxx is sensitive both to the ratio of U to V and to the size of the molecule. (rapid communication)

Ultrafast photophysics of pi-conjugated polymers for organic light emitting diode applications

Science.gov (United States)

Olejnik, Ella

In this work we used the pump-probe photomodulation (PM) spectroscopy technique to measure the transient PM spectrum and decay kinetics in various pi -- conjugated polymers (PCPs) films and blends. Using two ultrafast laser systems, we covered a broad spectral range from 0.25 -- 2.5 eV in the time domain from 200 fs to 1 ns with 150 fs time resolution. We also used continuous wave (CW) photomodulation spectroscopy, photoluminescence (PL), electro-absorption and doping-induced absorption to study the photoexcitations and other optical properties of PCPs and guest/ host blends. In particular we studied two different types of Poly(thienylenevinylene) polymer derivatives. One polymer type is the ordered regio-regular (RR) and regio-random (RRa) -- PTV in which the dark exciton, 2Ag is the lowest excited state. In these polymers the photoexcited exciton shows very fast decay kinetics due to the internal conversion to the dark exciton, which results in weak PL emission; thus these two polymers are non-luminescent. The other PTV derivative is the imide -- PTV which is more luminescent due to the proximity of 1Bu and 2Ag states, that results in longer decay kinetics and a difference between the calculated value of the QEPL (9%) and the measured one (1%). We also demonstrate transient strain spectroscopy in RR -- PTV thin films, where the ultrafast energy release associated with the exciton decay gives rise to substantial static and dynamic strains in the film that dramatically influences the film's transient PM response. We also study the photophysics of poly(dioctyloxy) phenylenevinylene polymer with different isotopes, where we substituted hydrogen (H-polymer) by deuterium (D-polymer), and 12C by 13C isotopes. From the transient decay kinetics measurements we found that the exciton recombination in DOO -- PPV consists of two processes. These are: intrinsic monomolecular, and exciton-exciton annihilation (bimolecular). In the D -- polymer, different probe frequencies of

Inkjet printing of conjugated polymer precursors on paper substrates for colorimetric sensing and flexible electrothermochromic display.

Science.gov (United States)

Yoon, Bora; Ham, Dae-Young; Yarimaga, Oktay; An, Hyosung; Lee, Chan Woo; Kim, Jong-Man

2011-12-08

Inkjet-printable aqueous suspensions of conjugated polymer precursors are developed for fabrication of patterned color images on paper substrates. Printing of a diacetylene (DA)-surfactant composite ink on unmodified paper and photopaper, as well as on a banknote, enables generation of latent images that are transformed to blue-colored polydiacetylene (PDA) structures by UV irradiation. Both irreversible and reversible thermochromism with the PDA printed images are demonstrated and applied to flexible and disposable sensors and to displays. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Streptavidin-conjugated CdSe/ZnS quantum dots impaired synaptic plasticity and spatial memory process

Energy Technology Data Exchange (ETDEWEB)

Gao Xiaoyan [Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf (Germany); Tang Mingliang [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (China); Li Zhifeng; Zha Yingying [University of Science and Technology of China, CAS Key Laboratory of Brain Function and Disease, and School of Life Sciences (China); Cheng Guosheng [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (China); Yin Shuting [Center for Molecular Neurobiology, University Medical Center Hamburg-Eppendorf (Germany); Chen Jutao; Ruan Diyun; Chen Lin; Wang Ming, E-mail: wming@ustc.edu.cn [University of Science and Technology of China, CAS Key Laboratory of Brain Function and Disease, and School of Life Sciences (China)

2013-04-15

Studies reported that quantum dots (QDs), as a novel probe, demonstrated a promising future for in vivo imaging, but also showed potential toxicity. This study is mainly to investigate in vivo response in the central nervous system (CNS) after exposure to QDs in a rat model of synaptic plasticity and spatial memory. Adult rats were exposed to streptavidin-conjugated CdSe/ZnS QDs (Qdots 525, purchased from Molecular Probes Inc.) by intraperitoneal injection for 7 days, followed by behavioral, electrophysiological, and biochemical examinations. The electrophysiological results show that input/output (I/O) functions were increased, while the peak of paired-pulse reaction and long-term potentiation were decreased after QDs insult, indicating synaptic transmission was enhanced and synaptic plasticity in the hippocampus was impaired. Meanwhile, behavioral experiments provide the evidence that QDs could impair rats' spatial memory process. All the results present evidences of interference of synaptic transmission and plasticity in rat hippocampal dentate gyrus area by QDs insult and suggest potential adverse issues which should be considered in QDs applications.

Streptavidin-conjugated CdSe/ZnS quantum dots impaired synaptic plasticity and spatial memory process

Science.gov (United States)

Gao, Xiaoyan; Tang, Mingliang; Li, Zhifeng; Zha, Yingying; Cheng, Guosheng; Yin, Shuting; Chen, Jutao; Ruan, Di-yun; Chen, Lin; Wang, Ming

2013-04-01

Studies reported that quantum dots (QDs), as a novel probe, demonstrated a promising future for in vivo imaging, but also showed potential toxicity. This study is mainly to investigate in vivo response in the central nervous system (CNS) after exposure to QDs in a rat model of synaptic plasticity and spatial memory. Adult rats were exposed to streptavidin-conjugated CdSe/ZnS QDs (Qdots 525, purchased from Molecular Probes Inc.) by intraperitoneal injection for 7 days, followed by behavioral, electrophysiological, and biochemical examinations. The electrophysiological results show that input/output ( I/ O) functions were increased, while the peak of paired-pulse reaction and long-term potentiation were decreased after QDs insult, indicating synaptic transmission was enhanced and synaptic plasticity in the hippocampus was impaired. Meanwhile, behavioral experiments provide the evidence that QDs could impair rats' spatial memory process. All the results present evidences of interference of synaptic transmission and plasticity in rat hippocampal dentate gyrus area by QDs insult and suggest potential adverse issues which should be considered in QDs applications.

Streptavidin-conjugated CdSe/ZnS quantum dots impaired synaptic plasticity and spatial memory process

International Nuclear Information System (INIS)

Gao Xiaoyan; Tang Mingliang; Li Zhifeng; Zha Yingying; Cheng Guosheng; Yin Shuting; Chen Jutao; Ruan Diyun; Chen Lin; Wang Ming

2013-01-01

Studies reported that quantum dots (QDs), as a novel probe, demonstrated a promising future for in vivo imaging, but also showed potential toxicity. This study is mainly to investigate in vivo response in the central nervous system (CNS) after exposure to QDs in a rat model of synaptic plasticity and spatial memory. Adult rats were exposed to streptavidin-conjugated CdSe/ZnS QDs (Qdots 525, purchased from Molecular Probes Inc.) by intraperitoneal injection for 7 days, followed by behavioral, electrophysiological, and biochemical examinations. The electrophysiological results show that input/output (I/O) functions were increased, while the peak of paired-pulse reaction and long-term potentiation were decreased after QDs insult, indicating synaptic transmission was enhanced and synaptic plasticity in the hippocampus was impaired. Meanwhile, behavioral experiments provide the evidence that QDs could impair rats’ spatial memory process. All the results present evidences of interference of synaptic transmission and plasticity in rat hippocampal dentate gyrus area by QDs insult and suggest potential adverse issues which should be considered in QDs applications.

Excited State Assignment and Laser Action in π-Conjugated Polymers

Science.gov (United States)

Vardeny, Z. V.

1998-03-01

We have applied a variety of ps transient and cw spectroscopies to elucidate the ground and excited electronic states of luminescent and nonluminescent thin films and solutions of π-conjugated polymers. These techniques include photoinduced absorption (PA), photoluminescence (PL), resonant Raman scattering (RRS), electro-absorption (EA), two photon absorption (TPA), and PA detected magnetic resonance. We found that the luminescence efficiency, the resonant and subgap third-order nonlinear optical properties and the RRS dispersion in these polymers are determined by the energies and symmetries of a subset of the excited states, including a series of singlet excitons with odd (B_u) and even (A_g) parity lying below a continuum band. Among them, the lowest Bu exciton (1B_u) and two other dominant Ag excitons (mAg and kA_g) are particularly important in determining the EA, TPA, and excitonic ps PA spectra.(S.V. Frolov, M. Liess, P.A. Lane, W. Gellermann, Z.V. Vardeny, M. Ozaki, and K. Yoshino, Phys. Rev. Lett). 78, 4285 (1997). We also found(M. Ozaki, E. Ehrenfreund, R.E. Benner, T.J. Baron, K. Yoshino, and Z.V. Vardeny, Phys. Rev. Lett). 79, 1762 (1997). that the RRS phonon dispersion with the laser excitation energy is governed by the dependence of lowest Ag exciton (2A_g) on the chain length distribution in the polymer. This leads to stronger RRS dispersion in nonluminescent polymers. Moreover the relative energies of the 1Bu and 2Ag excitons determine the PL quantum efficiency η, regardless of the ground state degeneracy. If E(2A_g) < E(1B_u) then η is small because of the dipole forbidden character of the lowest singlet. We will give examples of nonluminescent polymers which belong to this class with both degenerate and nondegenerate ground state, respectively. On the other hand, if E(1B_u) < E(2A_g) then η is large and the polymer might be considered as active material for display applications. Again we give examples of highly luminescent polymers with

Emission variation in infrared (CdSeTe)/ZnS quantum dots conjugated to antibodies

Energy Technology Data Exchange (ETDEWEB)

Jaramillo Gómez, J.A. [UPIITA – Instituto Politécnico Nacional, México D. F. 07320, México (Mexico); Casas Espinola, J.L., E-mail: jlcasas@esfm.ipn.mx [ESFM – Instituto Politécnico Nacional, México D. F. 07738, México (Mexico); Douda, J. [UPIITA – Instituto Politécnico Nacional, México D. F. 07320, México (Mexico)

2014-11-15

The paper presents the photoluminescence (PL) and Raman scattering investigations of infrared CdSeTe/ZnS quantum dots (QDs) with emission at 800 nm (1.60 eV) in nonconjugated states and after the conjugation to the anti-papilloma virus antibodies (Ab). The Raman scattering study has shown that the CdSeTe core includes two layers with different material compositions such as: CdSe{sub 0.5}Te{sub 0.5} and CdSe{sub 0.7}Te{sub 0.3}. PL spectra of nonconjugated CdSeTe/ZnS QDs are characterized by two Gaussian shape PL bands related to exciton emission in the CdSeTe core and in intermediate layer at the core/shell interface. PL spectra of bioconjugated QDs have changed essentially: the main PL band related to the core emission shifts into high energy and become asymmetric. The energy diagram of double core/shell CdSeTe/ZnS QDs has been analyzed to explain the PL spectrum of nonconjugated QDs and its transformation at the bioconjugation to the papiloma virus antibodies. It is shown that the PL spectrum transformation in bioconjugated QDs can be a powerful technique for biology and medicine.

Schottky diodes between Bi2S3 nanorods and metal nanoparticles in a polymer matrix as hybrid bulk-heterojunction solar cells

International Nuclear Information System (INIS)

Saha, Sudip K.; Pal, Amlan J.

2015-01-01

We report the use of metal-semiconductor Schottky junctions in a conjugated polymer matrix as solar cells. The Schottky diodes, which were formed between Bi 2 S 3 nanorods and gold nanoparticles, efficiently dissociated photogenerated excitons. The bulk-heterojunction (BHJ) devices based on such metal-semiconductor Schottky diodes in a polymer matrix therefore acted as an efficient solar cell as compared to the devices based on only the semiconductor nanorods in the polymer matrix or when gold nanoparticles were added separately to the BHJs. In the latter device, gold nanoparticles offered plasmonic enhancement due to an increased cross-section of optical absorption. We report growth and characteristics of the Schottky junctions formed through an intimate contact between Bi 2 S 3 nanorods and gold nanoparticles. We also report fabrication and characterization of BHJ solar cells based on such heterojunctions. We highlight the benefit of using metal-semiconductor Schottky diodes over only inorganic semiconductor nanorods or quantum dots in a polymer matrix in forming hybrid BHJ solar cells

Covalently bound conjugates of albumin and heparin: Synthesis, fractionation and characterization

NARCIS (Netherlands)

Hennink, Wim E.; Feijen, Jan; Ebert, Charles D.; Kim, Sung Wan

1983-01-01

Covalently bound conjugates of human serum albumin and heparin were prepared as compounds which could improve the blood-compatibility of polymer surfaces either by preadsorption or by covalent coupling of the conjugates onto blood contacting surfaces. The conjugates (10–16 weight % of heparin) were

Fluorescent molecularly imprinted polymer thin films for specific protein detection prepared with dansyl ethylenediamine-conjugated O-acryloyl L-hydroxyproline.

Science.gov (United States)

Inoue, Yuki; Kuwahara, Atsushi; Ohmori, Kohei; Sunayama, Hirobumi; Ooya, Tooru; Takeuchi, Toshifumi

2013-10-15

Protein-imprinted polymers, capable of specific transduction of protein binding events into fluorescent signal change, were designed and synthesized by using dansyl ethylenediamine-conjugated O-acryloyl L-hydroxyproline (Hyp-En-Dans). Human serum albumin (HSA) was used as a model target protein and HSA-imprinted polymers (HSA-IP) were prepared on glass substrates. Specific fluorescence change was observed for HSA binding on the imprinted polymer thin film, whereas a weaker response was observed for other proteins, including bovine serum albumin, chymotrypsin, lysozyme, and avidin. The binding specificity was found to derive from the rigid structure of the hydrogen-bondable pyrrolidine moiety. Compared with SPR measurements, the non-specific binding caused by the polymer matrix and/or randomly located fluorescent monomer residues that did not compose specific binding sites did not contribute to the observed fluorescence change. These results revealed that the proposed protein-imprinting technique using Hyp-En-Dans could provide a highly selective protein-sensing platform, in which only specific binding events would be detected by fluorescent measurements. Copyright © 2013 Elsevier B.V. All rights reserved.

The effect of changes in π-conjugated terthienyl systems using thienyl and ethylenedioxybenzene functionalized thieno[3,4-b]pyrazine precursors: Multicolored low band gap polymers

International Nuclear Information System (INIS)

Tarkuc, Simge; Unver, Elif Kose; Udum, Yasemin Arslan; Tanyeli, Cihangir; Toppare, Levent

2010-01-01

New classes of thieno[3,4-b]pyrazines containing thienyl and ethylenedioxy phenyl units on electron-withdrawing moieties of π-conjugated terthienyl were synthesized. The effect of structural differences on electrochemical and optoelectronic properties of the resulting polymers was investigated. Changes in the electronic nature of the functional groups enable to tune the electrochemical properties of the π-conjugated terthienyl monomers by lowering oxidation potential from 0.62 V (DTTP) to 0.56 V (DBTP). Spectroelectrochemical analyses revealed that the neutral polymer (PDBTP) is dark green in its neutral state revealing π-π* transitions in two well-separated bands at 410 and 751 nm. The electronic band gap of polymer, defined as the onset of the π-π* transition, is found to be 1.0 eV. Using the thienyl unit instead of ethylenedioxy phenyl, a red shift in the band gap (0.95 eV) is observed. The polymer, PDTTP, exhibits multicolor electrochromism and can be switched between a dark yellow neutral state, a green intermediate state, and a brown oxidized state. PDBTP also shows a multicolored electrochromic behavior with three distinct states: dark green at the neutral state, a brown intermediate state, and a brown-violet oxidized state.

Pronounced Side Chain Effects in Triple Bond-Conjugated Polymers Containing Naphthalene Diimides for n-Channel Organic Field-Effect Transistors

KAUST Repository

Nam, Sungho

2018-03-23

Three triple bond-conjugated naphthalene diimide (NDI) copolymers, poly{[N,N′-bis(2-R1)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-[(2,5-bis(2-R2)-1,4-phenylene)bis(ethyn-2,1-diyl)]} (PNDIR1-R2), were synthesized via Sonogashira coupling polymerization with varying alkyl side chains at the nitrogen atoms of the imide ring and 2,5-positions of the 1,4-diethynylbenzene moiety. Considering their identical polymer backbone structures, the side chains were found to have a strong influence on the surface morphology/nanostructure, thus playing a critical role in charge-transporting properties of the three NDI-based copolymers. Among the polymers, the one with an octyldodecyl (OD) chain at the nitrogen atoms of imide ring and a hexadecyloxy (HO) chain at the 2,5-positions of 1,4-diethynylbenzene, P(NDIOD-HO), exhibited the highest electron mobility of 0.016 cm2 V–1 s–1, as compared to NDI-based copolymers with an ethylhexyl chain at the 2,5-positions of 1,4-diethynylbenzene. The enhanced charge mobility in the P(NDIOD-HO) layers is attributed to the well-aligned nano-fiber-like surface morphology and highly ordered packing structure with a dominant edge-on orientation, thus enabling efficient in-plane charge transport. Our results on the molecular structure–charge transport property relationship in these materials may provide an insight into novel design of n-type conjugated polymers for applications in the organic electronics of the future.

Entanglement of conjugated polymer chains influences molecular self-assembly and carrier transport

KAUST Repository

Zhao, Kui; Khan, Hadayat Ullah; Li, Ruipeng; Su, Yisong; Amassian, Aram

2013-01-01

The influence of polymer entanglement on the self-assembly, molecular packing structure, and microstructure of low-Mw (lightly entangled) and high-Mw (highly entangled) poly (3-hexylthiophene) (P3HT), and the carrier transport in thin-film transistors, are investigated. The polymer chains are gradually disentangled in a marginal solvent via ultrasonication of the polymer solution, and demonstrate improved diffusivity of precursor species (coils, aggregates, and microcrystallites), enhanced nucleation and crystallization of P3HT in solution, and self-assembly of well-ordered and highly textured fibrils at the solid-liquid interface. In low-Mw P3HT, reducing chain entanglement enhances interchain and intrachain ordering, but reduces the interconnectivity of ordered domains (tie molecules) due to the presence of short chains, thus deteriorating carrier transport even in the face of improving crystallinity. Reducing chain entanglement in high-Mw P3HT solutions increases carrier mobility up to ≈20-fold, by enhancing interchain and intrachain ordering while maintaining a sufficiently large number of tie molecules between ordered domains. These results indicate that charge carrier mobility is strongly governed by the balancing of intrachain and interchain ordering, on the one hand, and interconnectivity of ordered domains, on the other hand. In high-Mw P3HT, intrachain and interchain ordering appear to be the key bottlenecks to charge transport, whereas in low-Mw P3HT, the limited interconnectivity of the ordered domains acts as the primary bottleneck to charge transport. Conjugated polymer chains of poly(3-hexylthiophene) (P3HT) are gradually disentangled in solution and trends in carrier transport mechanisms in organic thin film transistors for low- and high-molecular weight P3HT are investigated. While intrachain and interchain ordering within ordered domains are the key bottlenecks to charge transport in high-Mw P3HT films, the limited interconnectivity of ordered

Entanglement of conjugated polymer chains influences molecular self-assembly and carrier transport

KAUST Repository

Zhao, Kui

2013-06-26

The influence of polymer entanglement on the self-assembly, molecular packing structure, and microstructure of low-Mw (lightly entangled) and high-Mw (highly entangled) poly (3-hexylthiophene) (P3HT), and the carrier transport in thin-film transistors, are investigated. The polymer chains are gradually disentangled in a marginal solvent via ultrasonication of the polymer solution, and demonstrate improved diffusivity of precursor species (coils, aggregates, and microcrystallites), enhanced nucleation and crystallization of P3HT in solution, and self-assembly of well-ordered and highly textured fibrils at the solid-liquid interface. In low-Mw P3HT, reducing chain entanglement enhances interchain and intrachain ordering, but reduces the interconnectivity of ordered domains (tie molecules) due to the presence of short chains, thus deteriorating carrier transport even in the face of improving crystallinity. Reducing chain entanglement in high-Mw P3HT solutions increases carrier mobility up to ≈20-fold, by enhancing interchain and intrachain ordering while maintaining a sufficiently large number of tie molecules between ordered domains. These results indicate that charge carrier mobility is strongly governed by the balancing of intrachain and interchain ordering, on the one hand, and interconnectivity of ordered domains, on the other hand. In high-Mw P3HT, intrachain and interchain ordering appear to be the key bottlenecks to charge transport, whereas in low-Mw P3HT, the limited interconnectivity of the ordered domains acts as the primary bottleneck to charge transport. Conjugated polymer chains of poly(3-hexylthiophene) (P3HT) are gradually disentangled in solution and trends in carrier transport mechanisms in organic thin film transistors for low- and high-molecular weight P3HT are investigated. While intrachain and interchain ordering within ordered domains are the key bottlenecks to charge transport in high-Mw P3HT films, the limited interconnectivity of ordered

Controlling Film Morphology in Conjugated Polymer

Science.gov (United States)

Park, Lee Y.; Munro, Andrea M.; Ginger, David S.

2009-01-01

We study the effects of patterned surface chemistry on the microscale and nanoscale morphology of solution-processed donor/acceptor polymer-blend films. Focusing on combinations of interest in polymer solar cells, we demonstrate that patterned surface chemistry can be used to tailor the film morphology of blends of semiconducting polymers such as poly-[2-(3,7-dimethyloctyloxy)-5-methoxy-p-phenylenevinylene] (MDMO-PPV), poly-3-hexylthiophene (P3HT), poly[(9,9-dioctylflorenyl-2,7-diyl)-co-benzothiadiazole)] (F8BT), and poly(9,9-dioctylfluorene-co-bis-N,N’-(4-butylphenyl)-bis-N,N’-phenyl-1,4-phenylendiamine) (PFB) with the fullerene derivative, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). We present a method for generating patterned, fullerene-terminated monolayers on gold surfaces, and use microcontact printing and Dip-Pen Nanolithography (DPN) to pattern alkanethiols with both micro- and nanoscale features. After patterning with fullerenes and other functional groups, we backfill the rest of the surface with a variety of thiols to prepare substrates with periodic variations in surface chemistry. Spin coating polymer:PCBM films onto these substrates, followed by thermal annealing under nitrogen, leads to the formation of structured polymer films. We characterize these films with Atomic Force Microscopy (AFM), Raman spectroscopy, and fluorescence microscopy. The surface patterns are effective in guiding phase separation in all of the polymer:PCBM systems investigated, and lead to a rich variety of film morphologies that are inaccessible with unpatterned substrates. We demonstrate our ability to guide pattern formation in films thick enough of be of interest for actual device applications (up to 200 nm in thickness) using feature sizes as small as 100 nm. Finally, we show that the surface chemistry can lead to variations in film morphology on length scales significantly smaller than those used in generating the original surface patterns. The variety of

Comparative Study on the Efficiency of the Photodynamic Inactivation of Candida albicans Using CdTe Quantum Dots, Zn(II Porphyrin and Their Conjugates as Photosensitizers

Directory of Open Access Journals (Sweden)

Osnir S. Viana

2015-05-01

Full Text Available The application of fluorescent II-VI semiconductor quantum dots (QDs as active photosensitizers in photodymanic inactivation (PDI is still being evaluated. In the present study, we prepared 3 nm size CdTe QDs coated with mercaptosuccinic acid and conjugated them electrostatically with Zn(II meso-tetrakis (N-ethyl-2-pyridinium-2-yl porphyrin (ZnTE-2-PyP or ZnP, thus producing QDs-ZnP conjugates. We evaluated the capability of the systems, bare QDs and conjugates, to produce reactive oxygen species (ROS and applied them in photodynamic inactivation in cultures of Candida albicans by irradiating the QDs and testing the hypothesis of a possible combined contribution of the PDI action. Tests of in vitro cytotoxicity and phototoxicity in fibroblasts were also performed in the presence and absence of light irradiation. The overall results showed an efficient ROS production for all tested systems and a low cytotoxicity (cell viability >90% in the absence of radiation. Fibroblasts incubated with the QDs-ZnP and subjected to irradiation showed a higher cytotoxicity (cell viability <90% depending on QD concentration compared to the bare groups. The PDI effects of bare CdTe QD on Candida albicans demonstrated a lower reduction of the cell viability (~1 log10 compared to bare ZnP which showed a high microbicidal activity (~3 log10 when photoactivated. The QD-ZnP conjugates also showed reduced photodynamic activity against C. albicans compared to bare ZnP and we suggest that the conjugation with QDs prevents the transmembrane cellular uptake of the ZnP molecules, reducing their photoactivity.

In situ electron-beam polymerization stabilized quantum dot micelles.

Science.gov (United States)

Travert-Branger, Nathalie; Dubois, Fabien; Renault, Jean-Philippe; Pin, Serge; Mahler, Benoit; Gravel, Edmond; Dubertret, Benoit; Doris, Eric

2011-04-19

A polymerizable amphiphile polymer containing PEG was synthesized and used to encapsulate quantum dots in micelles. The quantum dot micelles were then polymerized using a "clean" electron beam process that did not require any post-irradiation purification. Fluorescence spectroscopy revealed that the polymerized micelles provided an organic coating that preserved the quantum dot fluorescence better than nonpolymerized micelles, even under harsh conditions. © 2011 American Chemical Society

Improved performance of nanowire–quantum-dot–polymer solar cells by chemical treatment of the quantum dot with ligand and solvent materials

International Nuclear Information System (INIS)

Nadarajah, A; Smith, T; Könenkamp, R

2012-01-01

We report a nanowire–quantum-dot–polymer solar cell consisting of a chemically treated CdSe quantum dot film deposited on n-type ZnO nanowires. The electron and hole collecting contacts are a fluorine-doped tin-oxide/zinc oxide layer and a P3HT/Au layer. This device architecture allows for enhanced light absorption and an efficient collection of photogenerated carriers. A detailed analysis of the chemical treatment of the quantum dots, their deposition, and the necessary annealing processes are discussed. We find that the surface treatment of CdSe quantum dots with pyridine, and the use of 1,2-ethanedithiol (EDT) ligands, critically improves the device performance. Annealing at 380 °C for 2 h is found to cause a structural conversion of the CdSe from its initial isolated quantum dot arrangement into a polycrystalline film with excellent surface conformality, thereby resulting in a further enhancement of device performance. Moreover, long-term annealing of 24 h leads to additional increases in device efficiency. Our best conversion efficiency reached for this type of cell is 3.4% under 85 mW cm −2 illumination. (paper)

Improving charge transport property and energy transfer with carbon quantum dots in inverted polymer solar cells

International Nuclear Information System (INIS)

Liu, Chunyu; Chang, Kaiwen; Guo, Wenbin; Li, Hao; Shen, Liang; Chen, Weiyou; Yan, Dawei

2014-01-01

Carbon quantum dots (Cdots) are synthesized by a simple method and introduced into active layer of polymer solar cells (PSCs). The performance of doped devices was apparently improved, and the highest power conversion efficiency of 7.05% was obtained, corresponding to a 28.2% enhancement compared with that of the contrast device. The charge transport properties, resistance, impedance, and transient absorption spectrum are systematically investigated to explore how the Cdots affect on PSCs performance. This study reveals the importance of Cdots in enhancing the efficiency of PSCs and gives insight into the mechanism of charge transport improvement.

Hybrid tandem quantum dot/organic photovoltaic cells with complementary near infrared absorption

KAUST Repository

Kim, Taesoo

2017-06-01

Monolithically integrated hybrid tandem solar cells that effectively combine solution-processed colloidal quantum dot (CQD) and organic bulk heterojunction subcells to achieve tandem performance that surpasses the individual subcell efficiencies have not been demonstrated to date. In this work, we demonstrate hybrid tandem cells with a low bandgap PbS CQD subcell harvesting the visible and near-infrared photons and a polymer:fullerene—poly (diketopyrrolopyrrole-terthiophene) (PDPP3T):[6,6]-phenyl-C60-butyric acid methyl ester (PC61BM)—top cell absorbing effectively the red and near-infrared photons of the solar spectrum in a complementary fashion. The two subcells are connected in series via an interconnecting layer (ICL) composed of a metal oxide layer, a conjugated polyelectrolyte, and an ultrathin layer of Au. The ultrathin layer of Au forms nano-islands in the ICL, reducing the series resistance, increasing the shunt resistance, and enhancing the device fill-factor. The hybrid tandems reach a power conversion efficiency (PCE) of 7.9%, significantly higher than the PCE of the corresponding individual single cells, representing one of the highest efficiencies reported to date for hybrid tandem solar cells based on CQD and polymer subcells.

Enhancing the Photoluminescence Emission of Conjugated MEH-PPV by Light Processing

KAUST Repository

Botiz, Ioan

2014-04-09

We show here that treatment of thin films of conjugated polymers by illumination with light leads to an increase of the intensity of their photoluminescence by up to 42%. The corresponding enhancement of absorbance was much less pronounced. We explain this significant enhancement of photoluminescence by a planarization of the conjugated polymer chains induced by photoexcitations even below the glass transition temperature, possibly due to an increased conjugation length. Interestingly, the photoluminescence remains at the enhanced level for more than 71 h after treatment of the films by illumination with light, likely due to the fact that below the glass transition temperature no restoring force could return the conjugated chains into their initial conformational state. © 2014 American Chemical Society.

Fluorinated arene, imide and unsaturated pyrrolidinone based donor acceptor conjugated polymers: Synthesis, structure-property and device studies

Science.gov (United States)

Liyanage, Arawwawala Don Thilanga

After the discovery of doped polyacetylene, organic semiconductor materials are widely studied as high impending active components in consumer electronics. They have received substantial consideration due to their potential for structural tailoring, low cost, large area and mechanically flexible alternatives to common inorganic semiconductors. To acquire maximum use of these materials, it is essential to get a strong idea about their chemical and physical nature. Material chemist has an enormous role to play in this novel area, including development of efficient synthetic methodologies and control the molecular self-assembly and (opto)-electronic properties. The body of this thesis mainly focuses on the substituent effects: how different substituents affect the (opto)-electronic properties of the donor-acceptor (D-A) conjugated polymers. The main priority goes to understand, how different alkyl substituent effect to the polymer solubility, crystallinity, thermal properties (e.g.: glass transition temperature) and morphological order. Three classes of D-A systems were extensively studied in this work. The second chapter mainly focuses on the synthesis and structure-property study of fluorinated arene (TFB) base polymers. Here we used commercially available 1,4-dibromo-2,3,5,6-tetrafluorobenzene (TFB) as the acceptor material and prepare several polymers using 3,3'-dialkyl(3,3'-R2T2) or 3,3'-dialkoxy bithiophene (3,3'-RO2T2) units as electron donors. A detail study was done using 3,3'-bithiophene donor units incorporating branched alkoxy-functionalities by systematic variation of branching position and chain length. The study allowed disentangling the branching effects on (i) aggregation tendency, intermolecular arrangement, (iii) solid state optical energy gaps, and (iv) electronic properties in an overall consistent picture, which might guide future polymer synthesis towards optimized materials for opto-electronic applications. The third chapter mainly focused on

Carbon quantum dots and a method of making the same

Science.gov (United States)

Zidan, Ragaiy; Teprovich, Joseph A.; Washington, Aaron L.

2017-08-22

The present invention is directed to a method of preparing a carbon quantum dot. The carbon quantum dot can be prepared from a carbon precursor, such as a fullerene, and a complex metal hydride. The present invention also discloses a carbon quantum dot made by reacting a carbon precursor with a complex metal hydride and a polymer containing a carbon quantum dot made by reacting a carbon precursor with a complex metal hydride.

A Possibility for Construction of an Iodine Cleaning System Based on Doping for π-Conjugated Polymers

Directory of Open Access Journals (Sweden)

Hiromasa Goto

2011-05-01

Full Text Available An iodine accumulation method using polyaniline (PANI and a textile composite is proposed. PANI/pulp paper sheets prepared by a paper making technique are suitable for iodine adsorption, because of good processability. The PANI-based paper sheets can be applied for iodine cleanup as air filters, water filters, and floorcloth. This concept may lead to a development of an iodine cleaning machine or iodine shield cloth based on π-conjugated polymer composites. In-situ vapor phase doping of iodine, observation of surface images, and IR measurements are carried out to examine iodine doping function for the PANI/pulp paper sheets.

End Functionalized Nonionic Water-Dispersible Conjugated Polymers.

Science.gov (United States)

Zhan, Ruoyu; Liu, Bin

2017-09-01

2,7-Dibromofluorene monomers carrying two or four oligo(ethylene glycol) (OEG) side chains are synthesized. Heck coupling between the monomers and 1,4-divinylbenzene followed by end capping with [4-(4-bromophenoxy)butyl]carbamic acid tert-butyl ester leads to two nonionic water-dispersible poly(fluorene-alt-1,4-divinylenephenylene)s end-functionalized with amine groups after hydrolysis. In water, the polymer with a lower OEG density (P1) has poor water dispersibility with a quantum yield of 0.24, while the polymer with a higher OEG density (P2) possesses excellent water-dispersibility with a high quantum yield of 0.45. Both polymers show fluorescence enhancement and blue-shifted absorption and emission maxima in the presence of surfactant sodium dodecyl sulfate and dodecyltrimethylammonium bromide. The polymers are also resistant to ionic strength with minimal nonspecific interactions to bovine serum albumin. When biotin is incorporated into the end of the polymer backbones through N-hydroxysuccinimide/amine coupling reaction, the biotinylated polymers interact specifically with streptavidin on solid surface. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High operational and environmental stability of high-mobility conjugated polymer field-effect transistors through the use of molecular additives

KAUST Repository

Nikolka, Mark; Nasrallah, Iyad; Rose, Bradley Daniel; Ravva, Mahesh Kumar; Broch, Katharina; Sadhanala, Aditya; Harkin, David; Charmet, Jerome; Hurhangee, Michael; Brown, Adam; Illig, Steffen; Too, Patrick; Jongman, Jan; McCulloch, Iain; Bredas, Jean-Luc; Sirringhaus, Henning

2016-01-01

Due to their low-temperature processing properties and inherent mechanical flexibility, conjugated polymer field-effect transistors (FETs) are promising candidates for enabling flexible electronic circuits and displays. Much progress has been made on materials performance; however, there remain significant concerns about operational and environmental stability, particularly in the context of applications that require a very high level of threshold voltage stability, such as active-matrix addressing of organic light-emitting diode displays. Here, we investigate the physical mechanisms behind operational and environmental degradation of high-mobility, p-type polymer FETs and demonstrate an effective route to improve device stability. We show that water incorporated in nanometre-sized voids within the polymer microstructure is the key factor in charge trapping and device degradation. By inserting molecular additives that displace water from these voids, it is possible to increase the stability as well as uniformity to a high level sufficient for demanding industrial applications.

High operational and environmental stability of high-mobility conjugated polymer field-effect transistors through the use of molecular additives

KAUST Repository

Nikolka, Mark

2016-12-12

Due to their low-temperature processing properties and inherent mechanical flexibility, conjugated polymer field-effect transistors (FETs) are promising candidates for enabling flexible electronic circuits and displays. Much progress has been made on materials performance; however, there remain significant concerns about operational and environmental stability, particularly in the context of applications that require a very high level of threshold voltage stability, such as active-matrix addressing of organic light-emitting diode displays. Here, we investigate the physical mechanisms behind operational and environmental degradation of high-mobility, p-type polymer FETs and demonstrate an effective route to improve device stability. We show that water incorporated in nanometre-sized voids within the polymer microstructure is the key factor in charge trapping and device degradation. By inserting molecular additives that displace water from these voids, it is possible to increase the stability as well as uniformity to a high level sufficient for demanding industrial applications.

Solid-phase synthesis of protein-polymers on reversible immobilization supports.

Science.gov (United States)

Murata, Hironobu; Carmali, Sheiliza; Baker, Stefanie L; Matyjaszewski, Krzysztof; Russell, Alan J

2018-02-27

Facile automated biomacromolecule synthesis is at the heart of blending synthetic and biologic worlds. Full access to abiotic/biotic synthetic diversity first occurred when chemistry was developed to grow nucleic acids and peptides from reversibly immobilized precursors. Protein-polymer conjugates, however, have always been synthesized in solution in multi-step, multi-day processes that couple innovative chemistry with challenging purification. Here we report the generation of protein-polymer hybrids synthesized by protein-ATRP on reversible immobilization supports (PARIS). We utilized modified agarose beads to covalently and reversibly couple to proteins in amino-specific reactions. We then modified reversibly immobilized proteins with protein-reactive ATRP initiators and, after ATRP, we released and analyzed the protein polymers. The activity and stability of PARIS-synthesized and solution-synthesized conjugates demonstrated that PARIS was an effective, rapid, and simple method to generate protein-polymer conjugates. Automation of PARIS significantly reduced synthesis/purification timelines, thereby opening a path to changing how to generate protein-polymer conjugates.

Diketopyrrolopyrrole Polymers for Organic Solar Cells.

Science.gov (United States)

Li, Weiwei; Hendriks, Koen H; Wienk, Martijn M; Janssen, René A J

2016-01-19

Conjugated polymers have been extensively studied for application in organic solar cells. In designing new polymers, particular attention has been given to tuning the absorption spectrum, molecular energy levels, crystallinity, and charge carrier mobility to enhance performance. As a result, the power conversion efficiencies (PCEs) of solar cells based on conjugated polymers as electron donor and fullerene derivatives as electron acceptor have exceeded 10% in single-junction and 11% in multijunction devices. Despite these efforts, it is notoriously difficult to establish thorough structure-property relationships that will be required to further optimize existing high-performance polymers to their intrinsic limits. In this Account, we highlight progress on the development and our understanding of diketopyrrolopyrrole (DPP) based conjugated polymers for polymer solar cells. The DPP moiety is strongly electron withdrawing and its polar nature enhances the tendency of DPP-based polymers to crystallize. As a result, DPP-based conjugated polymers often exhibit an advantageously broad and tunable optical absorption, up to 1000 nm, and high mobilities for holes and electrons, which can result in high photocurrents and good fill factors in solar cells. Here we focus on the structural modifications applied to DPP polymers and rationalize and explain the relationships between chemical structure and organic photovoltaic performance. The DPP polymers can be tuned via their aromatic substituents, their alkyl side chains, and the nature of the π-conjugated segment linking the units along the polymer chain. We show that these building blocks work together in determining the molecular conformation, the optical properties, the charge carrier mobility, and the solubility of the polymer. We identify the latter as a decisive parameter for DPP-based organic solar cells because it regulates the diameter of the semicrystalline DPP polymer fibers that form in the photovoltaic blends with

Stable and Efficient Organo-Metal Halide Hybrid Perovskite Solar Cells via π-Conjugated Lewis Base Polymer Induced Trap Passivation and Charge Extraction.

Science.gov (United States)

Qin, Ping-Li; Yang, Guang; Ren, Zhi-Wei; Cheung, Sin Hang; So, Shu Kong; Chen, Li; Hao, Jianhua; Hou, Jianhui; Li, Gang

2018-03-01

High-quality pinhole-free perovskite film with optimal crystalline morphology is critical for achieving high-efficiency and high-stability perovskite solar cells (PSCs). In this study, a p-type π-conjugated polymer poly[(2,6-(4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)-benzo[1,2-b:4,5-b'] dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl) benzo[1',2'-c:4',5'-c'] dithiophene-4,8-dione))] (PBDB-T) is introduced into chlorobenzene to form a facile and effective template-agent during the anti-solvent process of perovskite film formation. The π-conjugated polymer PBDB-T is found to trigger a heterogeneous nucleation over the perovskite precursor film and passivate the trap states of the mixed perovskite film through the formation of Lewis adducts between lead and oxygen atom in PBDB-T. The p-type semiconducting and hydrophobic PBDB-T polymer fills in the perovskite grain boundaries to improve charge transfer for better conductivity and prevent moisture invasion into the perovskite active layers. Consequently, the PSCs with PBDB-T modified anti-solvent processing leads to a high-efficiency close to 20%, and the devices show excellent stability, retaining about 90% of the initial power conversion efficiency after 150 d storage in dry air. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Templated self-assembly of quantum dots from aqueous solution using protein scaffolds

Energy Technology Data Exchange (ETDEWEB)

Blum, Amy Szuchmacher [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Soto, Carissa M [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Wilson, Charmaine D [Geo-Centers, Incorporated, Newton, MA 02459 (United States); Whitley, Jessica L [Geo-Centers, Incorporated, Newton, MA 02459 (United States); Moore, Martin H [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Sapsford, Kim E [George Mason University, 10910 University Boulevard, Manassas, VA 20110 (United States); Lin, Tianwei [Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037 (United States); Chatterji, Anju [Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037 (United States); Johnson, John E [Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037 (United States); Ratna, Banahalli R [Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States)

2006-10-28

Short, histidine-containing peptides can be conjugated to lysine-containing protein scaffolds to controllably attach quantum dots (QDs) to the scaffold, allowing for generic attachment of quantum dots to any protein without the use of specially engineered domains. This technique was used to bind quantum dots from aqueous solution to both chicken IgG and cowpea mosaic virus (CPMV), a 30 nm viral particle. These quantum dot-protein assemblies were studied in detail. The IgG-QD complexes were shown to retain binding specificity to their antigen after modification. The CPMV-QD complexes have a local concentration of quantum dots greater than 3000 nmol ml{sup -1}, and show a 15% increase in fluorescence quantum yield over free quantum dots in solution.

Fluorescence polarization measures energy funneling in single light-harvesting antennas--LH2 vs conjugated polymers.

Science.gov (United States)

Camacho, Rafael; Tubasum, Sumera; Southall, June; Cogdell, Richard J; Sforazzini, Giuseppe; Anderson, Harry L; Pullerits, Tõnu; Scheblykin, Ivan G

2015-10-19

Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ε). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ε = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET.

Entanglements in Marginal Solutions: A Means of Tuning Pre-Aggregation of Conjugated Polymers with Positive Implications for Charge Transport

KAUST Repository

Hu, Hanlin

2015-06-17

The solution-processing of conjugated polymers, just like commodity polymers, is subject to solvent and molecular weight-dependent solubility, interactions and chain entanglements within the polymer, all of which can influence the crystallization and microstructure development in semi-crystalline polymers and consequently affect charge transport and optoelectronic properties. Disentanglement of polymer chains in marginal solvents was reported to work via ultrasonication, facilitating the formation of photophysically ordered polymer aggregates. In this contribution, we explore how a wide range of technologically relevant solvents and formulations commonly used in organic electronics influence chain entanglement and the aggregation behaviour of P3HT using a combination of rheological and spectrophotometric measurements. The specific viscosity of the solution offers an excellent indication of the degree of entanglements in the solution, which is found to be related to the solubility of P3HT in a given solvent. Moreover, deliberately disentangling the solution in the presence of solvophobic driving forces, leads consistently to formation of photophysically visible aggregates which is indicative of local and perhaps long range order in the solute. We show for a broad range of solvents and molecular weights that disentanglement ultimately leads to significant ordering of the polymer in the solid state and a commensurate increase in charge transport properties. In doing so we demonstrate a remarkable ability to tune the microstructure which has important implications for transport properties. We discuss its potential implications in the context of organic photovoltaics.

Entanglements in Marginal Solutions: A Means of Tuning Pre-Aggregation of Conjugated Polymers with Positive Implications for Charge Transport

KAUST Repository

Hu, Hanlin; Zhao, Kui; Fernandes, Nikhil J.; Boufflet, Pierre; Bannock, James Henry; Yu, Liyang; de Mello, John C; Stingelin, Natalie; Heeney, Martin; Giannelis, Emmanuel P.; Amassian, Aram

2015-01-01

The solution-processing of conjugated polymers, just like commodity polymers, is subject to solvent and molecular weight-dependent solubility, interactions and chain entanglements within the polymer, all of which can influence the crystallization and microstructure development in semi-crystalline polymers and consequently affect charge transport and optoelectronic properties. Disentanglement of polymer chains in marginal solvents was reported to work via ultrasonication, facilitating the formation of photophysically ordered polymer aggregates. In this contribution, we explore how a wide range of technologically relevant solvents and formulations commonly used in organic electronics influence chain entanglement and the aggregation behaviour of P3HT using a combination of rheological and spectrophotometric measurements. The specific viscosity of the solution offers an excellent indication of the degree of entanglements in the solution, which is found to be related to the solubility of P3HT in a given solvent. Moreover, deliberately disentangling the solution in the presence of solvophobic driving forces, leads consistently to formation of photophysically visible aggregates which is indicative of local and perhaps long range order in the solute. We show for a broad range of solvents and molecular weights that disentanglement ultimately leads to significant ordering of the polymer in the solid state and a commensurate increase in charge transport properties. In doing so we demonstrate a remarkable ability to tune the microstructure which has important implications for transport properties. We discuss its potential implications in the context of organic photovoltaics.

Simulation Studies of LCST-like Phase Transitions in Elastin-like Polypeptides (ELPs) and Conjugates of ELP with Rigid Macromolecules

Science.gov (United States)

Condon, Joshua; Martin, Tyler; Jayaraman, Arthi

We use atomistic (AA) and coarse-grained (CG) molecular dynamics simulations to elucidate the thermodynamic driving forces governing lower critical solution temperature (LCST)-like phase transition exhibited by elastin-like peptides (ELPs) and conjugates of ELP with other macromolecules. In the AA simulations, we study ELP oligomers in explicit water, and mark the transition as the temperature at which they undergo a change in ``hydration'' state. While AA simulations are restricted to small systems of short ELPs and do not capture the chain aggregation observed in experiments of ELPs, they guide the phenomenological CG model development by highlighting the solvent induced polymer-polymer effective interactions with changing temperature. In the CG simulations, we capture the LCST polymer aggregation by increasing polymer-polymer effective attractive interactions in an implicit solvent. We examine the impact of conjugating a block of LCST polymer to another rigid unresponsive macromolecular block on the LCST-like transition. We find that when multiple LCST polymers are conjugated to a rigid polymer block, increased crowding of the LCST polymers shifts the onset of chain aggregation to smaller effective polymer-polymer attraction compared to the free LCST polymers. These simulation results provide guidance on the design of conjugated bio-mimetic thermoresponsive materials, and shape the fundamental understanding of the impact of polymer crowding on phase behavior in thermoresponsive LCST polymer systems.

Flexible organic/inorganic hybrid solar cells based on conjugated polymer and ZnO nanorod array

International Nuclear Information System (INIS)

Tong, Fei; Kim, Kyusang; Martinez, Daniel; Thapa, Resham; Ahyi, Ayayi; Williams, John; Park, Minseo; Kim, Dong-Joo; Lee, Sungkoo; Lim, Eunhee; Lee, Kyeong K

2012-01-01

We report on the photovoltaic characteristics of organic/inorganic hybrid solar cells fabricated on ‘flexible’ transparent substrates. The solar cell device is composed of ZnO nanorod array and the bulk heterojunction structured organic layer which is the blend of poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61 butyric acid methyl ester (PCBM). The ZnO nanorod array was grown on indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrates via a low-temperature (85 °C) aqueous solution process. The blend solution consisting of conjugated polymer P3HT and fullerene PCBM was spin coated at a low spinning rate of 400 rpm on top of the ZnO nanorod array structure and then the photoactive layer was slow dried at room temperature in air to promote its infiltration into the nanorod network. As a top electrode, silver was sputtered on top of the photoactive layer. The flexible solar cell with the structure of PET/ITO/ZnO thin film/ZnO nanorods/P3HT:PCBM/Ag exhibited a photovoltaic performance with an open circuit voltage (V OC ) of 0.52 V, a short circuit current density (J SC ) of 9.82 mA cm −2 , a fill factor (FF) of 35% and a power conversion efficiency (η) of 1.78%. All the measurements were performed under 100 mW cm −2 of illumination with an air mass 1.5 G filter. To the best of our knowledge, this is the first presentation of investigation into the fabrication and characterization of organic/inorganic hybrid solar cells based on bulk heterojunction structured conjugated polymer/fullerene photoactive layer and ZnO nanorod array constructed on flexible transparent substrates. (paper)

Amphiphilic Quantum Dots with Asymmetric, Mixed Polymer Brush Layers: From Single Core-Shell Nanoparticles to Salt-Induced Vesicle Formation

Directory of Open Access Journals (Sweden)

Brian R. Coleman

2018-03-01

Full Text Available A mixed micelle approach is used to produce amphiphilic brush nanoparticles (ABNPs with cadmium sulfide quantum dot (QD cores and surface layers of densely grafted (σ = ~1 chain/nm2 and asymmetric (fPS = 0.9 mixed polymer brushes that contain hydrophobic polystyrene (PS and hydrophilic poly(methyl methacrylate (PMAA chains (PS/PMAA-CdS. In aqueous media, the mixed brushes undergo conformational rearrangements that depend strongly on prior salt addition, giving rise to one of two pathways to fluorescent and morphologically disparate QD-polymer colloids. (A In the absence of salt, centrosymmetric condensation of PS chains forms individual core-shell QD-polymer colloids. (B In the presence of salt, non-centrosymmetric condensation of PS chains forms Janus particles, which trigger anisotropic interactions and amphiphilic self-assembly into the QD-polymer vesicles. To our knowledge, this is the first example of an ABNP building block that can form either discrete core-shell colloids or self-assembled superstructures in water depending on simple changes to the chemical conditions (i.e., salt addition. Such dramatic and finely tuned morphological variation could inform numerous applications in sensing, biolabeling, photonics, and nanomedicine.

Conformation Control of a Conjugated Polymer through Complexation with Bile Acids Generates Its Novel Spectral and Morphological Properties.

Science.gov (United States)

Tsuchiya, Youichi; Noguchi, Takao; Yoshihara, Daisuke; Roy, Bappaditya; Yamamoto, Tatsuhiro; Shinkai, Seiji

2016-11-29

Control of higher-order polymer structures attracts a great deal of interest for many researchers when they lead to the development of materials having various advanced functions. Among them, conjugated polymers that are useful as starting materials in the design of molecular wires are particularly attractive. However, an equilibrium existing between isolated chains and bundled aggregates is inevitable and has made their physical properties very complicated. As an attempt to simplify this situation, we previously reported that a polymer chain of a water-soluble polythiophene could be isolated through complexation with a helix-forming polysaccharide. More recently, a covalently self-threading polythiophene was reported, the main chain of which was physically protected from self-folding and chain-chain π-stacking. In this report, we wish to report a new strategy to isolate a water-soluble polythiophene and to control its higher-order structure by a supramolecular approach: that is, among a few bile acids, lithocholate can form stoichiometric complexes with cationic polythiophene to isolate the polymer chain, and the higher-order structure is changeable by the molar ratio. The optical and morphological studies have been thoroughly performed, and the resultant complex has been applied to the selective recognition of two AMP structural isomers.

Thiophene fused azacoronenes: regioselective synthesis, self organization, charge transport, and its incorporation in conjugated polymers

Science.gov (United States)

Liu, Yi; He, Bo

2015-09-15

A regioselective synthesis of an azacoronene fused with two peripheral thiophene groups has been realized through a concise synthetic route. The resulting thienoazacoronene (TAC) derivatives show high degree of self-organization in solution, in single crystals, in the bulk, and in spuncast thin films. Spuncast thin film field-effect transistors of the TACs exhibited mobilities up to 0.028 cm.sup.2V.sup.-1 S.sup.-1, which is among the top field effect mobilities for solution processed discotic materials. Organic photovoltaic devices using TAC-containing conjugated polymers as the donor material exhibited a high open-circuit voltage of 0.89 V, which was ascribable to TAC's low-lying highest occupied molecular orbital energy level.

Synthesis and luminescent properties of new conjugated polymers based on poly(p-phenylene vinylene)

Science.gov (United States)

Gurge, Ronald Matthew

The "push-pull" electronically substituted polymers poly(2 (5) -bromo-5 (2) -n-hexyloxy-1,4-phenylene vinylene), poly(2 (5) -chloro-5 (2) -n-hexyloxy-1,4-phenylene vinylene) and poly(2 (5) -fluoro-5 (2) -n-hexyloxy-1,4-phenylene vinylene) were synthesized by a soluble precursor method and were used to fabricate light emitting diode (LED) devices. Thermal elimination of the polyether precursors gives final conjugated polymers as flexible red films. Precursor polymers can be spin-cast from solutions onto indium/tin oxide (ITO) pretreated quartz plates, then thermally converted to the final red polymers. Light emitting diode fabrication is then completed by the thin film vapor deposition of calcium, followed by aluminum. LED devices of the "push-pull" polymers give light emission in the 620-635 nm range. Two fluorinated polymers, poly(2-fluoro-1,4-phenylene vinylene) and poly(2,5-difluoro-1,4-phenylene vinylene) were investigated for their electroluminescent (EL) properties. LED's using these materials as emissive layers show substantial EL wavelength shifts (560 nm and 600 nm, respectively) relative to emission from unsubstituted poly(1,4-phenylene vinylene) (565 nm). These differences in EL emission can be attributed to the electronic effects of fluorine substitution. Synthetic strategies were developed for copolymeric materials based on poly(1,4-phenylene vinylene). The alternating block copolymer, poly (1,8-octanedioxy-2,6-dimethoxy-1,4-phenylene-1,2-ethenylene-1,4-phenylene-1,2-ethenylene-1,4-phenylene-1,2-ethenylene- 3,5-dimethoxy-1,4-phenylene) was synthesized by a modified Wittig polymerization utilizing trialkyl phosphonium salts. This resulted in a regiospecific trans-olefination reaction when compared to polymeric materials synthesized through the use of common triaryl-phosphonium salts. Harsh post-Wittig isomerization procedures using Isb2 were bypassed as a result of the high trans-cis ratio of the final copolymer. It was fully characterized using the

White light generation tuned by dual hybridization of nanocrystals and conjugated polymers

International Nuclear Information System (INIS)

Demir, Hilmi Volkan; Nizamoglu, Sedat; Ozel, Tuncay; Mutlugun, Evren; Huyal, Ilkem Ozge; Sari, Emre; Holder, Elisabeth; Tian Nan

2007-01-01

Dual hybridization of highly fluorescent conjugated polymers and highly luminescent nanocrystals (NCs) is developed and demonstrated in multiple combinations for controlled white light generation with high color rendering index (CRI) (> 80) for the first time. The generated white light is tuned using layer-by-layer assembly of CdSe/ZnS core-shell NCs closely packed on polyfluorene, hybridized on near-UV emitting nitride-based light emitting diodes (LEDs). The design, synthesis, growth, fabrication and characterization of these hybrid inorganic-organic white LEDs are presented. The following experimental realizations are reported: (i) layer-by-layer hybridization of yellow NCs (λ PL =580 nm) and blue polyfluorene (λ PL =439 nm) with tristimulus coordinates of (x, y)=(0.31, 0.27), correlated color temperature of T c =6962 K and CRI of R a =53.4; (ii) layer-by-layer assembly of yellow and green NCs (λ PL =580 and 540 nm) and blue polyfluorene (λ PL =439 nm) with (x, y)=(0.23, 0.30), T c =14395 K and R a =65.7; and (iii) layer-by-layer deposition of yellow, green and red NCs (λ PL =580, 540 and 620 nm) and blue polyfluorene (λ PL =439 nm) with (x, y)=(0.38, 0.39), T c =4052 K and R a = 83.0. The CRI is demonstrated to be well controlled and significantly improved by increasing multi-chromaticity of the NC and polymer emitters

Implementing the conjugate gradient algorithm on multi-core systems

NARCIS (Netherlands)

Wiggers, W.A.; Bakker, Vincent; Kokkeler, Andre B.J.; Smit, Gerardus Johannes Maria; Nurmi, J.; Takala, J.; Vainio, O.

2007-01-01

In linear solvers, like the conjugate gradient algorithm, sparse-matrix vector multiplication is an important kernel. Due to the sparseness of the matrices, the solver runs relatively slow. For digital optical tomography (DOT), a large set of linear equations have to be solved which currently takes

Conjugated Polymer Solar Cells

Science.gov (United States)

2006-05-01

thermal gravimetry analysis (TGA)............... 12 2.6 Photoluminescence (PL) spectroscopy... gravimetry analysis (TGA) Thermal analysis of polymer films has been accomplished by TGA and DSC methods with the aid of Perkin-Elmer Series 7 Analysers...The MEH-PPV/acceptor films were prepared by spin-casting of the resulting mixture (with or without precipitate ) on glass substrates of diameter 23 mm

Photodynamic inactivation of bacteria using polyethylenimine-chlorin(e6) conjugates: Effect of polymer molecular weight, substitution ratio of chlorin(e6) and pH.

Science.gov (United States)

Huang, Liyi; Zhiyentayev, Timur; Xuan, Yi; Azhibek, Dulat; Kharkwal, Gitika B; Hamblin, Michael R

2011-04-01

Antimicrobial photodynamic therapy (APDT) is a novel technique to treat local infections. Previously we reported that the attachment of chlorin(e6) to polyethylenimine (PEI) polymers to form PEI-ce6 conjugates is an effective way to improve ce6 PDT activity against bacteria. The aim of this work was to explore how the polymer molecular weight, substitution ratio (SR) of ce6 and pH value affect the PDT efficacy. We have synthesized PEI-ce6(10) (MW = 60,000, SR = 1) and PEI-ce6(11) (MW = 60,000, SR = 5) and compared these with the previous PEI-ce6(9) (MW = 10,000, SR = 1). We tested the PDT efficacy of these three conjugates against Gram-negative E. coli and Gram-positive bacteria (S. aureus and E. fecalis) at three different pH values (5.0, 7.4, 10.0) that may affect the charge on both the bacterial cells and on the conjugate (that has both basic and acidic groups). PEI-ce6(9) and PEI-ce6(10) were the most effective against these tested bacteria. The PDT effect of all three conjugates depended on pH values. The effective order was pH = 10.0 > pH = 7.4 > pH = 5.0 on E. coli. For S. aureus and E. fecalis the order was pH = 5.0 > pH = 10.0 > pH = 7.4. PEI-ce6(11) PDT activity was worse than PEI-ce6(10) activity which is probably connected to the fact that ce6 molecules are self-quenched within the PEI-ce6(11) molecule. Ce6 quenching within the PEI-ce6 molecules was proved by analyzing fluorescence spectra of PEI-ce6 conjugates at different pH values. There were no differences in bacterial uptake between different pH values in three PEI-ce6 conjugates. We assume high pH (rather than low pH as was hypothesized) disaggregates the conjugates, so the higher pH was more effective than the lower pH against E. coli. But for Gram-positive bacteria, low pH was more effective possibly due to more overall positive charge on the conjugate. Copyright © 2011 Wiley-Liss, Inc.

Interfacial molecular order of conjugated polymer in P3HT:ZnO bilayer photovoltaics and its impact on device performance

KAUST Repository

Wood, Sebastian

2013-01-01

Hybrid (organic-oxide) photovoltaic device performance is highly dependent on the nature and quality of the organic-oxide interface. This work investigates the details of interfacial morphology in terms of the molecular order of poly(3-hexylthiophene) (P3HT) at the planar interface with zinc oxide (ZnO) formed by pulsed laser deposition. Resonant Raman spectroscopy is employed as a powerful morphological probe for conjugated polymers to reveal that the interfacial P3HT is disrupted during the deposition process whereas the bulk polymer shows an increase in molecular order. External quantum efficiency measurements of P3HT:ZnO bilayer devices show that this disordered P3HT region is active in photocurrent generation. © 2013 AIP Publishing LLC.

CONJUGATED POLYMERS AND POLYELECTROLYTES IN SOLAR PHOTOCONVERSION, Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Schanze, Kirk S [University of Florida

2014-08-05

This DOE-supported program investigated the fundamental properties of conjugated polyelectrolytes, with emphasis placed on studies of excited state energy transport, self-assembly into conjugated polyelectroyte (CPE) based films and colloids, and exciton transport and charge injection in CPE films constructed atop wide bandgap semiconductors. In the most recent grant period we have also extended efforts to examine the properties of low-bandgap donor-acceptor conjugated polyelectrolytes that feature strong visible light absorption and the ability to adsorb to metal-oxide interfaces.

Albumin–Polymer–Drug Conjugates: Long Circulating, High Payload Drug Delivery Vehicles

DEFF Research Database (Denmark)

Smith, Anton Allen Abbotsford; Zuwala, Kaja; Pilgram, Oliver

2016-01-01

Albumin is an exquisite tool of nature used in biomedicine to achieve long blood residence time for drugs, but the payload it can carry is typically limited to one molecule per protein. In contrast, synthetic macromolecular prodrugs contain multiple copies of drugs per polymer chain but offer only...... a marginal increase in the circulation lifetime of the drugs. We combine the benefits of the two platforms and at the same time overcome their respective limitations. Specifically, we develop the synthesis of albumin–polymer–drug conjugates to obtain long circulating, high payload drug delivery vehicles....... In vivo data validate that albumin endows the conjugate with a blood residence time similar to that of the protein and well exceeding that of the polymer. Therapeutic activity of the conjugates is validated using prodrugs of panobinostat, an HIV latency reversal agent, in which case the conjugates matched...

Transient photoconductivity and femtosecond nonlinear optical properties of a conjugated polymer-graphene oxide composite

Energy Technology Data Exchange (ETDEWEB)

Nalla, Venkatram; Ji Wei [Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Polavarapu, Lakshminarayana; Manga, Kiran Kumar; Goh, Bee Min; Loh, Kian Ping; Xu Qinghua, E-mail: chmxqh@nus.edu.sg, E-mail: phyjiwei@nus.edu.sg [Department of Chemistry, National University of Singapore, Singapore 117543 (Singapore)

2010-10-15

A water soluble conjugated thiophene polymer, sodium salt of poly[2-(3-thienyl)ethoxy-4-butylsulfonate] (TPP), and graphene oxide (GO) composite film (GO-TPP) device was prepared. Transient photoconductivity measurements were carried out on the GO-TPP composite film using 150 ns laser pulses of 527 nm wavelength. Highly efficient photocurrent generation was observed from the GO-TPP film. The relationships of the film photoconductivity, photocurrent decay time and electron decay times with the incident light intensity were investigated. The photoconductive gain of the film was determined to be greater than 40% and to be independent of the light intensity. Furthermore, the femtosecond nonlinear optical properties of the GO-TPP film were measured using 800 nm femtosecond laser pulses and the composite film exhibited high nonlinear absorption and nonlinear refraction coefficients.

Transient photoconductivity and femtosecond nonlinear optical properties of a conjugated polymer-graphene oxide composite

International Nuclear Information System (INIS)

Nalla, Venkatram; Ji Wei; Polavarapu, Lakshminarayana; Manga, Kiran Kumar; Goh, Bee Min; Loh, Kian Ping; Xu Qinghua

2010-01-01

A water soluble conjugated thiophene polymer, sodium salt of poly[2-(3-thienyl)ethoxy-4-butylsulfonate] (TPP), and graphene oxide (GO) composite film (GO-TPP) device was prepared. Transient photoconductivity measurements were carried out on the GO-TPP composite film using 150 ns laser pulses of 527 nm wavelength. Highly efficient photocurrent generation was observed from the GO-TPP film. The relationships of the film photoconductivity, photocurrent decay time and electron decay times with the incident light intensity were investigated. The photoconductive gain of the film was determined to be greater than 40% and to be independent of the light intensity. Furthermore, the femtosecond nonlinear optical properties of the GO-TPP film were measured using 800 nm femtosecond laser pulses and the composite film exhibited high nonlinear absorption and nonlinear refraction coefficients.

Controlling morphology and chain aggregation in semiconducting conjugated polymers: the role of solvent on optical gain in MEH-PPV.

Science.gov (United States)

Lampert, Zach E; Reynolds, C Lewis; Papanikolas, John M; Aboelfotoh, M Osama

2012-10-25

We report the results of a detailed investigation that addresses the influence of polymer morphology and chain aggregation, as controlled by the chemical nature of the solvent, on the optical gain properties of the conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV). Using the variable stripe length technique in the picosecond regime, we have extensively studied the optical gain performance of asymmetric planar waveguides formed with thin MEH-PPV films spin-cast from concentrated chlorobenzene (CB) and tetrahydrofuran (THF) solutions onto thermally oxidized silicon substrates. CB and THF solvents were chosen based on their known ability to promote and effectively limit aggregate formation, respectively. Very large net gain coefficients are demonstrated, reaching values of 330 and 365 cm(-1), respectively, when optically pumping the waveguides with a maximum energy density of 85 μJ/cm(2). Our results clearly demonstrate that polymer morphology, and hence, the chain conformation dependence of the degree of aggregation in the films as controlled by the solvent, has minimal impact on the net gain. Moreover, the waveguides exhibit low loss coefficients of 10-20 cm(-1) at the ASE wavelength. These results question the importance of polymer morphology and aggregate formation in polymer-based optical devices operating at high excitation densities in the stimulated emission regime as would be characteristic of lasers and optical amplifiers.

Self-Assembly and Crystallization of Conjugated Block Copolymers

Science.gov (United States)

Davidson, Emily Catherine

This dissertation demonstrates the utility of molecular design in conjugated polymers to create diblock copolymers that robustly self-assemble in the melt and confine crystallization upon cooling. This work leverages the model conjugated polymer poly(3-(2'-ethyl)hexylthiophene) (P3EHT), which features a branched side chain, resulting in a dramatically reduced melting temperature (Tm 80°C) relative to the widely-studied poly(3-hexylthiophene) (P3HT) (Tm 200°C). This reduced melting temperature permits an accessible melt phase, without requiring that the segregation strength (chiN) be dramatically increased. Thus, diblock copolymers containing P3EHT demonstrate robust diblock copolymer self-assembly in the melt over a range of compositions and morphologies. Furthermore, confined crystallization in the case of both glassy (polystyrene (PS) matrix block) and soft (polymethylacrylate (PMA) matrix block) confinement is studied, with the finding that even in soft confinement, crystallization is constrained within the diblock microdomains. This success demonstrates the strategy of leveraging molecular design to decrease the driving force for crystallization as a means to achieving robust self-assembly and confined crystallization in conjugated block copolymers. Importantly, despite the relatively flexible nature of P3EHT in the melt, the diblock copolymer phase behavior appears to be significantly impacted by the stiffness (persistence length of 3 nm) of the P3EHT chain compared to the coupled amorphous blocks (persistence length 0.7 nm). In particular, it is shown that the synthesized morphologies are dominated by a very large composition window for lamellar geometries (favored at high P3EHT volume fractions); cylindrical geometries are favored when P3EHT is the minority fraction. This asymmetry of the composition window is attributed to impact of conformational asymmetry (the difference in chain stiffness, as opposed to shape) between conjugated and amorphous blocks

Polymers targeting habitual diseases

Science.gov (United States)

The use of polymeric drug conjugates mainly for the treatment for cancer therapy has been addressed, but these polymers also find their way in treatment of various lifestyle disorders like diabetes, hypertension, cardiovascular diseases etc. The focus is being laid to develop biodegradable polymer ...

Dual-excitation upconverting nanoparticle and quantum dot aptasensor for multiplexed food pathogen detection.

Science.gov (United States)

Kurt, Hasan; Yüce, Meral; Hussain, Babar; Budak, Hikmet

2016-07-15

In this report, a dual-excitation sensing method was developed using aptamer-functionalized quantum dots and upconverting nanoparticles, exhibiting Stokes and anti-Stokes type excitation profiles, respectively. Conjugation of the aptamer-functionalized luminescent nanoparticles with the magnetic beads, comprising short DNA sequences that were partially complementary to the aptamer sequences, enabled facile separation of the analyte-free conjugates for fluorescent measurement. UV-Visible spectroscopy, Circular Dichroism spectroscopy, Dynamic Light Scattering and Polyacrylamide Gel Electrophoresis techniques were used to characterize the aptamer probes developed. The target-specific luminescent conjugates were applied for multiplex detection of model food pathogens, Salmonella typhimurium, and Staphylococcus aureus, in which the fluorescent emission spectra were obtained under UV excitation at 325nm for quantum dots and NIR excitation at 980nm for upconverting nanoparticles, respectively. The dual-excitation strategy was aimed to minimize cross-talk between the luminescent signals for multiplexed detection, and yielded limit of detection values of 16 and 28cfumL(-1) for Staphylococcus aureus, and Salmonella typhimurium, respectively. By employing a greater number of quantum dots and upconverting nanoparticles with non-overlapping fluorescent emissions, the proposed methodology might be exploited further to detect several analytes, simultaneously. Copyright © 2016 Elsevier B.V. All rights reserved.

Fluorescent carbon quantum dots synthesized by chemical vapor deposition: An alternative candidate for electron acceptor in polymer solar cells

Science.gov (United States)

Cui, Bo; Yan, Lingpeng; Gu, Huimin; Yang, Yongzhen; Liu, Xuguang; Ma, Chang-Qi; Chen, Yongkang; Jia, Husheng

2018-01-01

Excitation-wavelength-dependent blue-greenish fluorescent carbon quantum dots (CQDs) with graphite structure were synthesized by chemical vapor deposition (CVD) method. In comparison with those synthesized by hydrothermal method (named H-CQDs), C-CQDs have less hydrophilic terminal groups, showing good solubility in common organic solvents. Furthermore, these synthesized C-CQDs show a low LUMO energy level (LUMO = -3.84 eV), which is close to that of phenyl-C61-butyric acid methyl ester (PC61BM, LUMO = -4.01 eV), the most widely used electron acceptor in polymer solar cells. Photoluminescence quenching of the poly(3-hexylthiophene-2,5-diyl):C-CQDs blended film (P3HT:C-CQDs) indicated that a photo-induced charge transfer between P3HT and C-CQDs occurs in such a composite film. Bulk heterojunction solar cells using C-CQDs as electron acceptors or doping materials were fabricated and tested. High fill factors were achieved for these C-CQDs based polymer solar cells, demonstrating that CQDs synthesized by CVD could be alternative to the fullerene derivatives for applying in polymer solar cells.

Method to create gradient index in a polymer

Science.gov (United States)

Dirk, Shawn M; Johnson, Ross Stefan; Boye, Robert; Descour, Michael R; Sweatt, William C; Wheeler, David R; Kaehr, Bryan James

2014-10-14

Novel photo-writable and thermally switchable polymeric materials exhibit a refractive index change of .DELTA.n.gtoreq.1.0 when exposed to UV light or heat. For example, lithography can be used to convert a non-conjugated precursor polymer to a conjugated polymer having a higher index-of-refraction. Further, two-photon lithography can be used to pattern high-spatial frequency structures.

Mortalin antibody-conjugated quantum dot transfer from human mesenchymal stromal cells to breast cancer cells requires cell–cell interaction

Energy Technology Data Exchange (ETDEWEB)

Pietilä, Mika [National Institute of Advanced industrial Sciences and Technology, Tsukuba, Ibaraki 305 8562 (Japan); Lehenkari, Petri [Institute of Biomedicine, Department of Anatomy and Cell Biology, University of Oulu, Aapistie 7, P.O. Box 5000, FIN-90014 (Finland); Institute of Clinical Medicine, Division of Surgery, University of Oulu and Clinical Research Centre, Department of Surgery and Intensive Care, Oulu University Hospital, Aapistie 5a, P.O. Box 5000, FIN-90014 (Finland); Kuvaja, Paula [Institute of Biomedicine, Department of Anatomy and Cell Biology, University of Oulu, Aapistie 7, P.O. Box 5000, FIN-90014 (Finland); Department of Pathology, Oulu University Hospital, P.O. Box 50, FIN-90029 OYS, Oulu (Finland); Kaakinen, Mika [Biocenter Oulu, University of Oulu, P.O. Box 5000, FI-90014 (Finland); Kaul, Sunil C.; Wadhwa, Renu [National Institute of Advanced industrial Sciences and Technology, Tsukuba, Ibaraki 305 8562 (Japan); Uemura, Toshimasa, E-mail: t.uemura@aist.go.jp [National Institute of Advanced industrial Sciences and Technology, Tsukuba, Ibaraki 305 8562 (Japan)

2013-11-01

The role of tumor stroma in regulation of breast cancer growth has been widely studied. However, the details on the type of heterocellular cross-talk between stromal and breast cancer cells (BCCs) are still poorly known. In the present study, in order to investigate the intercellular communication between human mesenchymal stromal cells (hMSCs) and breast cancer cells (BCCs, MDA-MB-231), we recruited cell-internalizing quantum dots (i-QD) generated by conjugation of cell-internalizing anti-mortalin antibody and quantum dots (QD). Co-culture of illuminated and color-coded hMSCs (QD655) and BCCs (QD585) revealed the intercellular transfer of QD655 signal from hMSCs to BCCs. The amount of QD double positive BCCs increased gradually within 48 h of co-culture. We found prominent intercellular transfer of QD655 in hanging drop co-culture system and it was non-existent when hMSCs and BBCs cells were co-cultured in trans-well system lacking imminent cell–cell contact. Fluorescent and electron microscope analyses also supported that the direct cell-to-cell interactions may be required for the intercellular transfer of QD655 from hMSCs to BCCs. To the best of our knowledge, the study provides a first demonstration of transcellular crosstalk between stromal cells and BCCs that involve direct contact and may also include a transfer of mortalin, an anti-apoptotic and growth-promoting factor enriched in cancer cells.

Fluorescence polarization measures energy funneling in single light-harvesting antennas—LH2 vs conjugated polymers

Science.gov (United States)

Camacho, Rafael; Tubasum, Sumera; Southall, June; Cogdell, Richard J.; Sforazzini, Giuseppe; Anderson, Harry L.; Pullerits, Tõnu; Scheblykin, Ivan G.

2015-10-01

Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ɛ). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ɛ = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET.

Driving High-Performance n- and p-type Organic Transistors with Carbon Nanotube/Conjugated Polymer Composite Electrodes Patterned Directly from Solution

KAUST Repository

Hellstrom, Sondra L.

2010-07-12

We report patterned deposition of carbon nanotube/conjugated polymer composites from solution with high nanotube densities and excellent feature resolution. Such composites are suited for use as electrodes in high-performance transistors of pentacene and C60, with bottom-contact mobilities of ?0.5 and ?1 cm2 V-1 s-1, respectively. This represents a clear step towards development of inexpensive, high-performance all-organic circuits. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Long Lived Photoexcitation Dynamics in π-Conjugated Polymer/PbS Quantum Dot Blended Films for Photovoltaic Application

Directory of Open Access Journals (Sweden)

Ruizhi Wang

2017-08-01

Full Text Available We used continuous wave photoinduced absorption (PIA spectroscopy to investigate long-lived polarons in a blend of PbS quantum dot and regio-regular poly (3-hexylthiophene (RR-P3HT. The charge transfer from RR-P3HT to PbS as well as from PbS to RR-P3HT were observed after changing the capping ligand of PbS from a long chain molecular to a short one. Therefore, PbS could be used to extend the working spectral range in hybrid solar cells with a proper capping ligand. However, we found that the recombination mechanism in the millisecond time region is dominated by the trap/defects in blended films, while it improves to a bimolecular recombination partially after ligand exchange. Our results suggest that passivating traps of nanocrystals by improving surface ligands will be crucial for relevant solar cell applications.

Adsorption of quantum dots onto polymer and Gemini surfactant films: a quartz crystal microbalance study.

Science.gov (United States)

Alejo, T; Merchán, M D; Velázquez, M M

2014-08-26

We used quartz crystal microbalance with dissipation to study the mechanical properties, the kinetics of adsorption, and the amount of CdSe quantum dots (QDs) adsorbed onto a SiO2 sensor, referred as bare sensor, onto the sensor modified with a film of the polymer poly(maleic anhydride-alt-1-octadecene), PMAO, or with a film of the Gemini surfactant ethyl-bis(dimethyl octadecyl ammonium bromide), abbreviated as 18-2-18. Results showed that when the sensor is coated with polymer or surfactant molecules, the coverage increases compared with that obtained for the bare sensor. On the other hand, rheological properties and kinetics of adsorption of QDs are driven by QD nanoparticles. Thus, the QD films present elastic behavior, and the elasticity values are independent of the molecule used as coating and similar to the elasticity value obtained for QDs films on the bare sensor. The QD adsorption is a two-step mechanism in which the fastest process is attributed to the QD adsorption onto the solid substrate and the slowest one is ascribed to rearrangement movements of the nanoparticles adsorbed at the surface.

Interplay of alternative conjugated pathways and steric interactions on the electronic and optical properties of donor-acceptor conjugated polymers

KAUST Repository

Lima, Igo T.; Risko, Chad; Aziz, Saadullah Gary; Da Silva Filho, Demé trio A Da Silva; Bredas, Jean-Luc

2014-01-01

Donor-acceptor π-conjugated copolymers are of interest for a wide range of electronic applications, including field-effect transistors and solar cells. Here, we present a density functional theory (DFT) study of the impact of varying the conjugation pathway on the geometric, electronic, and optical properties of donor-acceptor systems. We consider both linear ("in series"), traditional conjugation among the donor-acceptor moieties versus structures where the acceptor units are appended orthogonally to the linear, donor-only conjugated backbone. Long-range-corrected hybrid functionals are used in the investigation with the values of the tuned long-range separation parameters providing an estimate of the extent of conjugation as a function of the oligomer architecture. Considerable differences in the electronic and optical properties are determined as a function of the nature of the conjugation pathway, features that should be taken into account in the design of donor-acceptor copolymers.

Transparent and flexible quantum dot-polymer composites using an ionic liquid as compatible polymerization medium

International Nuclear Information System (INIS)

Woelfle, Caroline; Claus, Richard O

2007-01-01

Quantum dot (QD)-polymer composites were fabricated based on a solution of QDs dispersed in an ionic liquid. Positively charged water-soluble nanocrystals were obtained from solutions of CdSe/ZnS QDs dispersed in toluene by ligand exchange with 2-dimethylaminoethanethiol (DAET). The resulting QDs were further transferred into a hydrophobic ionic liquid HMITFSI (1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) by cation exchange, resulting in a CdSe/ZnS-HMITFSI solution, which was used as a compatible medium for the polymerization and cross-linking of polymethyl methacrylate networks. Transparent, fluorescent and flexible materials resulted. The quantum yields of the composites depended on the initial properties of the QDs dispersed in toluene, and medium-size QDs (2.6 nm) resulted in the highest quantum yields

Hybrid polymer-inorganic photovoltaic cells

NARCIS (Netherlands)

Beek, W.J.E.; Janssen, R.A.J.; Merhari, L.

2009-01-01

Composite materials made from organic conjugated polymers and inorganic semiconductors such as metal oxides attract considerable interest for photovoltaic applications. Hybrid polymer-inorganic solar cells offer the opportunity to combine the beneficial properties of the two materials in charge

Non-covalent functionalization of carbon nanotubes: Controlling Chirality Selectivity via Alkyl Groups of Conjugated Co-Polymers

Science.gov (United States)

Weight, Braden; Gifford, Brendan; Kilina, Svetlana

Carbon nanotubes (CNTs) play an important role in nanotechnology, including electronics, chemical sensors, and solar cells. Their electronic and optical properties depend on the size and geometry (chirality) of the nanotube. However, one main concern regarding nanotube application in optoelectronic devices is the difficulty of separating them based upon chirality after synthesis, as all known synthesis methods produce more than one chirality simultaneously. To get around this, one method is the functionalization of the CNTs via non-covalent bonding of co-polymers by wrapping them around the tube. We use force field simulations to explore the effects of various structural manipulations to the co-polymer 9,9-dialkylfluorenyl-2,7-diyl bipyridine (PFO-BPY) to find the preferential mechanisms of selective interactions between the PFO-BPY and CNTs of various chiralities. In particular, we focus on the effect of the branching in alkyl side-groups of PFO-BPY on their binding to the CNT surface. We have observed correlations between the side-group structures and their wrapping morphology on the CNT-Polymer interactions. Our calculations demonstrate that the branching in the position closest to the conjugated backboned results in the strongest interaction with all CNT. This research was supported by the National Science Foundation (CHE 1413614) and the Center for Computationally-Assisted Science and Technology at NDSU.

Aptamer-Modified Semiconductor Quantum Dots for Biosensing Applications.

Science.gov (United States)

Wen, Lin; Qiu, Liping; Wu, Yongxiang; Hu, Xiaoxiao; Zhang, Xiaobing

2017-07-28

Semiconductor quantum dots have attracted extensive interest in the biosensing area because of their properties, such as narrow and symmetric emission with tunable colors, high quantum yield, high stability and controllable morphology. The introduction of various reactive functional groups on the surface of semiconductor quantum dots allows one to conjugate a spectrum of ligands, antibodies, peptides, or nucleic acids for broader and smarter applications. Among these ligands, aptamers exhibit many advantages including small size, high chemical stability, simple synthesis with high batch-to-batch consistency and convenient modification. More importantly, it is easy to introduce nucleic acid amplification strategies and/or nanomaterials to improve the sensitivity of aptamer-based sensing systems. Therefore, the combination of semiconductor quantum dots and aptamers brings more opportunities in bioanalysis. Here we summarize recent advances on aptamer-functionalized semiconductor quantum dots in biosensing applications. Firstly, we discuss the properties and structure of semiconductor quantum dots and aptamers. Then, the applications of biosensors based on aptamer-modified semiconductor quantum dots by different signal transducing mechanisms, including optical, electrochemical and electrogenerated chemiluminescence approaches, is discussed. Finally, our perspectives on the challenges and opportunities in this promising field are provided.

Aptamer-Modified Semiconductor Quantum Dots for Biosensing Applications

Directory of Open Access Journals (Sweden)

Lin Wen

2017-07-01

Full Text Available Semiconductor quantum dots have attracted extensive interest in the biosensing area because of their properties, such as narrow and symmetric emission with tunable colors, high quantum yield, high stability and controllable morphology. The introduction of various reactive functional groups on the surface of semiconductor quantum dots allows one to conjugate a spectrum of ligands, antibodies, peptides, or nucleic acids for broader and smarter applications. Among these ligands, aptamers exhibit many advantages including small size, high chemical stability, simple synthesis with high batch-to-batch consistency and convenient modification. More importantly, it is easy to introduce nucleic acid amplification strategies and/or nanomaterials to improve the sensitivity of aptamer-based sensing systems. Therefore, the combination of semiconductor quantum dots and aptamers brings more opportunities in bioanalysis. Here we summarize recent advances on aptamer-functionalized semiconductor quantum dots in biosensing applications. Firstly, we discuss the properties and structure of semiconductor quantum dots and aptamers. Then, the applications of biosensors based on aptamer-modified semiconductor quantum dots by different signal transducing mechanisms, including optical, electrochemical and electrogenerated chemiluminescence approaches, is discussed. Finally, our perspectives on the challenges and opportunities in this promising field are provided.

Synthesis, characterization and the release kinetics of antiproliferative agents from polyamidoamine conjugates

CSIR Research Space (South Africa)

Aderibigbe, BA

2015-01-01

Full Text Available Polyamidoamine conjugates containing curcumin and bisphosphonate were synthesized via a one-pot aqueous phase Michael addition reaction. In the design of the conjugate, bisphosphonate formed an integral part of the polymer carrier backbone. Curcumin...

Time-Domain Ab Initio Analysis of Excitation Dynamics in a Quantum Dot/Polymer Hybrid: Atomistic Description Rationalizes Experiment.

Science.gov (United States)

Long, Run; Prezhdo, Oleg V

2015-07-08

Hybrid organic/inorganic polymer/quantum dot (QD) solar cells are an attractive alternative to the traditional cells. The original, simple models postulate that one-dimensional polymers have continuous energy levels, while zero-dimensional QDs exhibit atom-like electronic structure. A realistic, atomistic viewpoint provides an alternative description. Electronic states in polymers are molecule-like: finite in size and discrete in energy. QDs are composed of many atoms and have high, bulk-like densities of states. We employ ab initio time-domain simulation to model the experimentally observed ultrafast photoinduced dynamics in a QD/polymer hybrid and show that an atomistic description is essential for understanding the time-resolved experimental data. Both electron and hole transfers across the interface exhibit subpicosecond time scales. The interfacial processes are fast due to strong electronic donor-acceptor, as evidenced by the densities of the photoexcited states which are delocalized between the donor and the acceptor. The nonadiabatic charge-phonon coupling is also strong, especially in the polymer, resulting in rapid energy losses. The electron transfer from the polymer is notably faster than the hole transfer from the QD, due to a significantly higher density of acceptor states. The stronger molecule-like electronic and charge-phonon coupling in the polymer rationalizes why the electron-hole recombination inside the polymer is several orders of magnitude faster than in the QD. As a result, experiments exhibit multiple transfer times for the long-lived hole inside the QD, ranging from subpicoseconds to nanoseconds. In contrast, transfer of the short-lived electron inside the polymer does not occur beyond the first picosecond. The energy lost by the hole on its transit into the polymer is accommodated by polymer's high-frequency vibrations. The energy lost by the electron injected into the QD is accommodated primarily by much lower-frequency collective and