Investigation of strain heterogeneities by laser scanning extensometry in strain ageing materials: application to zirconium alloys

International Nuclear Information System (INIS)

Graff, S.; Forest, S.; Strudel, J.L.; Dierke, H.; Neuhauser, H.; Prioul, C.; Bechade, J.L.

2005-01-01

Laser scanning extensometry was used to detect and characterize propagating plastic instabilities such as the Luders bands at the millimeter scale. Spatio-temporal plastic heterogeneities are due to either static or dynamic strain ageing (SSA and DSA) phenomena. Regarding zirconium alloys, different type of heterogeneities were observed: their features strongly depended on mechanical test conditions. In one case, they appeared to be non propagating but preserved along the stress-strain curve and were associated with SSA effects such as stress peaks after relaxation periods or after unloading steps with waiting times. In other case, they appeared as non propagating but were not associated with SSA effects. (authors)

Radiative transport-based frequency-domain fluorescence tomography

International Nuclear Information System (INIS)

Joshi, Amit; Rasmussen, John C; Sevick-Muraca, Eva M; Wareing, Todd A; McGhee, John

2008-01-01

We report the development of radiative transport model-based fluorescence optical tomography from frequency-domain boundary measurements. The coupled radiative transport model for describing NIR fluorescence propagation in tissue is solved by a novel software based on the established Attila(TM) particle transport simulation platform. The proposed scheme enables the prediction of fluorescence measurements with non-contact sources and detectors at a minimal computational cost. An adjoint transport solution-based fluorescence tomography algorithm is implemented on dual grids to efficiently assemble the measurement sensitivity Jacobian matrix. Finally, we demonstrate fluorescence tomography on a realistic computational mouse model to locate nM to μM fluorophore concentration distributions in simulated mouse organs

Site-specific multipoint fluorescence measurement system with end-capped optical fibers.

Science.gov (United States)

Song, Woosub; Moon, Sucbei; Lee, Byoung-Cheol; Park, Chul-Seung; Kim, Dug Young; Kwon, Hyuk Sang

2011-07-10

We present the development and implementation of a spatially and spectrally resolved multipoint fluorescence correlation spectroscopy (FCS) system utilizing multiple end-capped optical fibers and an inexpensive laser source. Specially prepared end-capped optical fibers placed in an image plane were used to both collect fluorescence signals from the sample and to deliver signals to the detectors. The placement of independently selected optical fibers on the image plane was done by monitoring the end-capped fiber tips at the focus using a CCD, and fluorescence from specific positions of a sample were collected by an end-capped fiber, which could accurately represent light intensities or spectral data without incurring any disturbance. A fast multipoint spectroscopy system with a time resolution of ∼1.5 ms was then implemented using a prism and an electron multiplying charge coupled device with a pixel binning for the region of interest. The accuracy of our proposed system was subsequently confirmed by experimental results, based on an FCS analysis of microspheres in distilled water. We expect that the proposed multipoint site-specific fluorescence measurement system can be used as an inexpensive fluorescence measurement tool to study many intracellular and molecular dynamics in cell biology. © 2011 Optical Society of America

Fluorescence imaging spectrometer optical design

Science.gov (United States)

Taiti, A.; Coppo, P.; Battistelli, E.

2015-09-01

The optical design of the FLuORescence Imaging Spectrometer (FLORIS) studied for the Fluorescence Explorer (FLEX) mission is discussed. FLEX is a candidate for the ESA's 8th Earth Explorer opportunity mission. FLORIS is a pushbroom hyperspectral imager foreseen to be embarked on board of a medium size satellite, flying in tandem with Sentinel-3 in a Sun synchronous orbit at a height of about 815 km. FLORIS will observe the vegetation fluorescence and reflectance within a spectral range between 500 and 780 nm. Multi-frames acquisitions on matrix detectors during the satellite movement will allow the production of 2D Earth scene images in two different spectral channels, called HR and LR with spectral resolution of 0.3 and 2 nm respectively. A common fore optics is foreseen to enhance by design the spatial co-registration between the two spectral channels, which have the same ground spatial sampling (300 m) and swath (150 km). An overlapped spectral range between the two channels is also introduced to simplify the spectral coregistration. A compact opto-mechanical solution with all spherical and plane optical elements is proposed, and the most significant design rationales are described. The instrument optical architecture foresees a dual Babinet scrambler, a dioptric telescope and two grating spectrometers (HR and LR), each consisting of a modified Offner configuration. The developed design is robust, stable vs temperature, easy to align, showing very high optical quality along the whole field of view. The system gives also excellent correction for transverse chromatic aberration and distortions (keystone and smile).

X-ray fluorescence imaging with polycapillary X-ray optics

International Nuclear Information System (INIS)

Yonehara, Tasuku; Yamaguchi, Makoto; Tsuji, Kouichi

2010-01-01

X-ray fluorescence spectrometry imaging is a powerful tool to provide information about the chemical composition and elemental distribution of a specimen. X-ray fluorescence spectrometry images were conventionally obtained by using a μ-X-ray fluorescence spectrometry spectrometer, which requires scanning a sample. Faster X-ray fluorescence spectrometry imaging would be achieved by eliminating the process of sample scanning. Thus, we developed an X-ray fluorescence spectrometry imaging instrument without sample scanning by using polycapillary X-ray optics, which had energy filter characteristics caused by the energy dependence of the total reflection phenomenon. In the present paper, we show that two independent straight polycapillary X-ray optics could be used as an energy filter of X-rays for X-ray fluorescence. Only low energy X-rays were detected when the angle between the two optical axes was increased slightly. Energy-selective X-ray fluorescence spectrometry images with projection mode were taken by using an X-ray CCD camera equipped with two polycapillary optics. It was shown that Fe Kα (6.40 keV) and Cu Kα (8.04 keV) could be discriminated for Fe and Cu foils.

DNA-Based Self-Assembly of Fluorescent Nanodiamonds.

Science.gov (United States)

Zhang, Tao; Neumann, Andre; Lindlau, Jessica; Wu, Yuzhou; Pramanik, Goutam; Naydenov, Boris; Jelezko, Fedor; Schüder, Florian; Huber, Sebastian; Huber, Marinus; Stehr, Florian; Högele, Alexander; Weil, Tanja; Liedl, Tim

2015-08-12

As a step toward deterministic and scalable assembly of ordered spin arrays we here demonstrate a bottom-up approach to position fluorescent nanodiamonds (NDs) with nanometer precision on DNA origami structures. We have realized a reliable and broadly applicable surface modification strategy that results in DNA-functionalized and perfectly dispersed NDs that were then self-assembled in predefined geometries. With optical studies we show that the fluorescence properties of the nitrogen-vacancy color centers in NDs are preserved during surface modification and DNA assembly. As this method allows the nanoscale arrangement of fluorescent NDs together with other optically active components in complex geometries, applications based on self-assembled spin lattices or plasmon-enhanced spin sensors as well as improved fluorescent labeling for bioimaging could be envisioned.

Functional imaging in bulk tissue specimens using optical emission tomography: fluorescence preservation during optical clearing

International Nuclear Information System (INIS)

Sakhalkar, H S; Dewhirst, M; Oliver, T; Cao, Y; Oldham, M

2007-01-01

Optical emission computed tomography (optical-ECT) is a technique for imaging the three-dimensional (3D) distribution of fluorescent probes in biological tissue specimens with high contrast and spatial resolution. In optical-ECT, functional information can be imaged by (i) systemic application of functional labels (e.g. fluorophore labelled proteins) and/or (ii) endogenous expression of fluorescent reporter proteins (e.g. red fluorescent protein (RFP), green fluorescent protein (GFP)) in vivo. An essential prerequisite for optical-ECT is optical clearing, a procedure where tissue specimens are made transparent to light by sequential perfusion with fixing, dehydrating and clearing agents. In this study, we investigate clearing protocols involving a selection of common fixing (4% buffered paraformaldehyde (PFA), methanol and ethanol), dehydrating (methanol and ethanol) and clearing agents (methyl salicylate and benzyl-alcohol-benzyl-benzoate (BABB)) in order to determine a 'fluorescence friendly' clearing procedure. Cell culture experiments were employed to optimize the sequence of chemical treatments that best preserve fluorescence. Texas red (TxRed), fluorescein isothiocyanate (FITC), RFP and GFP were tested as fluorophores and fluorescent reporter proteins of interest. Fluorescent and control cells were imaged on a microscope using a DSred2 and FITC filter set. The most promising clearing protocols of cell culture experiments were applied to whole xenograft tumour specimens, to test their effectiveness in large unsectioned samples. Fluorescence of TxRed/FITC fluorophores was not found to be significantly affected by any of the test clearing protocols. RFP and GFP fluorescence, however, was found to be significantly greater when cell fixation was in ethanol. Fixation in either PFA or methanol resulted in diminished fluorescence. After ethanol fixation, the RFP and GFP fluorescence proved remarkably robust to subsequent exposure to either methyl salicylate or BABB

Functional imaging in bulk tissue specimens using optical emission tomography: fluorescence preservation during optical clearing

Energy Technology Data Exchange (ETDEWEB)

Sakhalkar, H S [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Dewhirst, M [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Oliver, T [Department of Cell Biology, Duke University Medical Center, Durham, NC 27710 (United States); Cao, Y [Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710 (United States); Oldham, M [Department of Radiation Oncology Physics, and Biomedical Engineering, Duke University Medical Center, Durham, NC 27710 (United States)

2007-04-21

Optical emission computed tomography (optical-ECT) is a technique for imaging the three-dimensional (3D) distribution of fluorescent probes in biological tissue specimens with high contrast and spatial resolution. In optical-ECT, functional information can be imaged by (i) systemic application of functional labels (e.g. fluorophore labelled proteins) and/or (ii) endogenous expression of fluorescent reporter proteins (e.g. red fluorescent protein (RFP), green fluorescent protein (GFP)) in vivo. An essential prerequisite for optical-ECT is optical clearing, a procedure where tissue specimens are made transparent to light by sequential perfusion with fixing, dehydrating and clearing agents. In this study, we investigate clearing protocols involving a selection of common fixing (4% buffered paraformaldehyde (PFA), methanol and ethanol), dehydrating (methanol and ethanol) and clearing agents (methyl salicylate and benzyl-alcohol-benzyl-benzoate (BABB)) in order to determine a 'fluorescence friendly' clearing procedure. Cell culture experiments were employed to optimize the sequence of chemical treatments that best preserve fluorescence. Texas red (TxRed), fluorescein isothiocyanate (FITC), RFP and GFP were tested as fluorophores and fluorescent reporter proteins of interest. Fluorescent and control cells were imaged on a microscope using a DSred2 and FITC filter set. The most promising clearing protocols of cell culture experiments were applied to whole xenograft tumour specimens, to test their effectiveness in large unsectioned samples. Fluorescence of TxRed/FITC fluorophores was not found to be significantly affected by any of the test clearing protocols. RFP and GFP fluorescence, however, was found to be significantly greater when cell fixation was in ethanol. Fixation in either PFA or methanol resulted in diminished fluorescence. After ethanol fixation, the RFP and GFP fluorescence proved remarkably robust to subsequent exposure to either methyl salicylate

Fiber optic-based fluorescence detection system for in vivo studies of exogenous chromophore pharmacokinetics

Science.gov (United States)

Doiron, Daniel R.; Dunn, J. B.; Mitchell, W. L.; Dalton, Brian K.; Garbo, Greta M.; Warner, Jon A.

1995-05-01

The detection and quantification of the concentration of exogenous chromophores in-vivo by their fluorescence is complicated by many physical and geometrical parameters. Measurement of such signals is advantageous in determining the pharmacokinetics of photosensitizers such as those used in photodynamic therapy (PDT) or to assist in the diagnosis of tissue histological state. To overcome these difficulties a ratio based fiber optic contact fluorometer has been developed. This fluorescence detection system (FDS) uses the ratio of the fluorescence emission peak of the exogenous chromophore to that of endogenous chromophores, i.e. autofluorescence, to correct for a variety of parameters affecting the magnitude of the measured signals. By doing so it also minimizes the range of baseline measurements prior to exogenous drug injection, for various tissue types. Design of the FDS and results of its testing in animals and patients using the second generation photosensitizer Tin ethyletiopurpurin (SnET2) are presented. These results support the feasibility and usefulness of the Ratio FDS system.

Holographic fluorescence microscopy with incoherent digital holographic adaptive optics.

Science.gov (United States)

Jang, Changwon; Kim, Jonghyun; Clark, David C; Lee, Seungjae; Lee, Byoungho; Kim, Myung K

2015-01-01

Introduction of adaptive optics technology into astronomy and ophthalmology has made great contributions in these fields, allowing one to recover images blurred by atmospheric turbulence or aberrations of the eye. Similar adaptive optics improvement in microscopic imaging is also of interest to researchers using various techniques. Current technology of adaptive optics typically contains three key elements: a wavefront sensor, wavefront corrector, and controller. These hardware elements tend to be bulky, expensive, and limited in resolution, involving, for example, lenslet arrays for sensing or multiactuator deformable mirrors for correcting. We have previously introduced an alternate approach based on unique capabilities of digital holography, namely direct access to the phase profile of an optical field and the ability to numerically manipulate the phase profile. We have also demonstrated that direct access and compensation of the phase profile are possible not only with conventional coherent digital holography, but also with a new type of digital holography using incoherent light: selfinterference incoherent digital holography (SIDH). The SIDH generates a complex—i.e., amplitude plus phase—hologram from one or several interferograms acquired with incoherent light, such as LEDs, lamps, sunlight, or fluorescence. The complex point spread function can be measured using guide star illumination and it allows deterministic deconvolution of the full-field image. We present experimental demonstration of aberration compensation in holographic fluorescence microscopy using SIDH. Adaptive optics by SIDH provides new tools for improved cellular fluorescence microscopy through intact tissue layers or other types of aberrant media.

Applications of optical fiber to remote laser fluorescence analysis

International Nuclear Information System (INIS)

Kim, Cheol Jung; Shin, Jang Soo; Lee, Sang Mock; Kim, Jeong Moog; Kim, Duk Heon; Hong, Seok Kyung

1991-12-01

Fluorescence analysis using time-resolved laser fluorimetry has been used for trace uranium analysis because this method shows high sensitivity and low detection limit and is less matrix dependent than any other fluorimetric measurement. By this time, the uranium analyses in the solution of reprocessing process or high radioactive area have been primarily analyzed by sampling of the solution, but recently, a study on a remote uranium fluorescence analysis using optical fiber has been setting out based on the development of an optical fiber with radiation resistivity and of an advanced laser excitation source. Laser fluorimetry developed by our laboratory for trace uranium analyses in uranium handling process or in urine samples of workers in a nuclear facility has been used in our institute since 1988. A development of the system for remote control of uranium fluorescence analysis will be expected to contribute to an on-line uranium concentration monitoring in the cooling water of reconversion stream. In this report, we summarize the information related to fluorescence analyses and remote fluorescence monitoring methods established by foreign countries and our laboratory. We also present a future research direction for remote on-line monitoring of uranium in conversion or reconversion process. (Author)

Imaging subsurface damage of grinded fused silica optics by confocal fluorescence microscopy

International Nuclear Information System (INIS)

Neauport, J.; Cormont, P.; Destribats, J.; Legros, P.; Ambard, C.

2009-01-01

We report an experimental investigation of fluorescence confocal microscopy as a tool to measure subsurface damage on grinded fused silica optics. Confocal fluorescence microscopy was performed with an excitation at the wavelength of 405 nm on fixed abrasive diamond grinded fused silica samples. We detail the measured fluorescence spectrums and compare them to those of oil based coolants and grinding slurries. We evidence that oil based coolant used in diamond grinding induces a fluorescence that marks the subsurface damages and eases its observation. Such residual traces might also be involved in the laser damage process. (authors)

Handheld Fluorescence Microscopy based Flow Analyzer.

Science.gov (United States)

Saxena, Manish; Jayakumar, Nitin; Gorthi, Sai Siva

2016-03-01

Fluorescence microscopy has the intrinsic advantages of favourable contrast characteristics and high degree of specificity. Consequently, it has been a mainstay in modern biological inquiry and clinical diagnostics. Despite its reliable nature, fluorescence based clinical microscopy and diagnostics is a manual, labour intensive and time consuming procedure. The article outlines a cost-effective, high throughput alternative to conventional fluorescence imaging techniques. With system level integration of custom-designed microfluidics and optics, we demonstrate fluorescence microscopy based imaging flow analyzer. Using this system we have imaged more than 2900 FITC labeled fluorescent beads per minute. This demonstrates high-throughput characteristics of our flow analyzer in comparison to conventional fluorescence microscopy. The issue of motion blur at high flow rates limits the achievable throughput in image based flow analyzers. Here we address the issue by computationally deblurring the images and show that this restores the morphological features otherwise affected by motion blur. By further optimizing concentration of the sample solution and flow speeds, along with imaging multiple channels simultaneously, the system is capable of providing throughput of about 480 beads per second.

Applications of optical fiber to the remote fluorescence analysis

International Nuclear Information System (INIS)

Shin, Jang Soo; Kim, Duck Hueon; Lee, Soo Ho

1992-12-01

The laser fluorometer developed in 1987 has been used in real circumstances for trace uranium analysis. And, we have been trying to improve the instrument to be able to apply in analytical circumstances of remote measurement using optical fiber. The N 2 laser beam and the resulting fluorescence light could be successfully transmitted through a quartz-made optical fiber. The wavelength resolution and the fluorescence decay time resolution induced by pulsed N 2 laser were used to the uranium fluorescence analyses. The fluorescence of uranium in nitric acid medium was measured successfully using the system. The fluorescence signal was analysed using simplex method which is useful to deconvolute the mixed signals. An analytical method using thermal lens effect was developed. The method will be a complementary one for the fluorescence measurement. (Author)

The Effects of Heteroatoms Si and S on Tuning the Optical Properties of Rhodamine- and Fluorescein-Based Fluorescence Probes: A Theoretical Analysis.

Science.gov (United States)

Zhou, Panwang; Ning, Cai; Alsaedi, Ahmed; Han, Keli

2016-10-05

The effects of the incorporated heteroatoms Si and S on tuning the optical properties of rhodamine- and fluorescein-based fluorescence probes is investigated using DFT and time-dependent DFT with four different functionals. As previously proposed, the large redshift (90 nm) produced by a Si atom in both the absorption and emission spectra can be attributed to the σ*-π* conjugation between the σ* orbital of the Si atom and the π* orbital of the adjacent carbon atoms. However, the presence of a Si atom does not alter the fluorescence quenching mechanism of the nonfluorescent forms of the investigated compounds. For the first time, these theoretical results indicate that the n orbital of the S atom plays an important role in determining the optical properties of the nonfluorescent form of rhodamine-based fluorescence probes. It alters the fluorescence quenching mechanism by lowering the energy of the dark nπ* state, which is due to breakage of the C10-S52 bond upon photoexcitation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Super-resolution fluorescence microscopy by stepwise optical saturation

Science.gov (United States)

Zhang, Yide; Nallathamby, Prakash D.; Vigil, Genevieve D.; Khan, Aamir A.; Mason, Devon E.; Boerckel, Joel D.; Roeder, Ryan K.; Howard, Scott S.

2018-01-01

Super-resolution fluorescence microscopy is an important tool in biomedical research for its ability to discern features smaller than the diffraction limit. However, due to its difficult implementation and high cost, the super-resolution microscopy is not feasible in many applications. In this paper, we propose and demonstrate a saturation-based super-resolution fluorescence microscopy technique that can be easily implemented and requires neither additional hardware nor complex post-processing. The method is based on the principle of stepwise optical saturation (SOS), where M steps of raw fluorescence images are linearly combined to generate an image with a M-fold increase in resolution compared with conventional diffraction-limited images. For example, linearly combining (scaling and subtracting) two images obtained at regular powers extends the resolution by a factor of 1.4 beyond the diffraction limit. The resolution improvement in SOS microscopy is theoretically infinite but practically is limited by the signal-to-noise ratio. We perform simulations and experimentally demonstrate super-resolution microscopy with both one-photon (confocal) and multiphoton excitation fluorescence. We show that with the multiphoton modality, the SOS microscopy can provide super-resolution imaging deep in scattering samples. PMID:29675306

Methodological challenges of optical tweezers-based X-ray fluorescence imaging of biological model organisms at synchrotron facilities.

Science.gov (United States)

Vergucht, Eva; Brans, Toon; Beunis, Filip; Garrevoet, Jan; Bauters, Stephen; De Rijcke, Maarten; Deruytter, David; Janssen, Colin; Riekel, Christian; Burghammer, Manfred; Vincze, Laszlo

2015-07-01

Recently, a radically new synchrotron radiation-based elemental imaging approach for the analysis of biological model organisms and single cells in their natural in vivo state was introduced. The methodology combines optical tweezers (OT) technology for non-contact laser-based sample manipulation with synchrotron radiation confocal X-ray fluorescence (XRF) microimaging for the first time at ESRF-ID13. The optical manipulation possibilities and limitations of biological model organisms, the OT setup developments for XRF imaging and the confocal XRF-related challenges are reported. In general, the applicability of the OT-based setup is extended with the aim of introducing the OT XRF methodology in all research fields where highly sensitive in vivo multi-elemental analysis is of relevance at the (sub)micrometre spatial resolution level.

Enzyme-enhanced fluorescence detection of DNA on etched optical fibers.

Science.gov (United States)

Niu, Shu-yan; Li, Quan-yi; Ren, Rui; Zhang, Shu-sheng

2009-05-15

A novel DNA biosensor based on enzyme-enhanced fluorescence detection on etched optical fibers was developed. The hybridization complex of DNA probe and biotinylated target was formed on the etched optical fiber, and was then bound with streptavidin labeled horseradish peroxidase (streptavidin-HRP). The target DNA was quantified through the fluorescent detection of bi-p,p'-4-hydroxyphenylacetic acid (DBDA) generated from the substrate 4-hydroxyphenylacetic acid (p-HPA) under the catalysis of HRP, with a detection limit of 1 pM and a linear range from 1.69 pM to 169 pM. It is facile to regenerate this sensor through surface treatment with concentrated urea solution. It was discovered that the sensor can retain 70% of its original activity after three detection-regeneration cycles.

Challenges in paper-based fluorogenic optical sensing with smartphones

Science.gov (United States)

Ulep, Tiffany-Heather; Yoon, Jeong-Yeol

2018-05-01

Application of optically superior, tunable fluorescent nanotechnologies have long been demonstrated throughout many chemical and biological sensing applications. Combined with microfluidics technologies, i.e. on lab-on-a-chip platforms, such fluorescent nanotechnologies have often enabled extreme sensitivity, sometimes down to single molecule level. Within recent years there has been a peak interest in translating fluorescent nanotechnology onto paper-based platforms for chemical and biological sensing, as a simple, low-cost, disposable alternative to conventional silicone-based microfluidic substrates. On the other hand, smartphone integration as an optical detection system as well as user interface and data processing component has been widely attempted, serving as a gateway to on-board quantitative processing, enhanced mobility, and interconnectivity with informational networks. Smartphone sensing can be integrated to these paper-based fluorogenic assays towards demonstrating extreme sensitivity as well as ease-of-use and low-cost. However, with these emerging technologies there are always technical limitations that must be addressed; for example, paper's autofluorescence that perturbs fluorogenic sensing; smartphone flash's limitations in fluorescent excitation; smartphone camera's limitations in detecting narrow-band fluorescent emission, etc. In this review, physical optical setups, digital enhancement algorithms, and various fluorescent measurement techniques are discussed and pinpointed as areas of opportunities to further improve paper-based fluorogenic optical sensing with smartphones.

Optical imaging of non-fluorescent nanoparticle probes in live cells

Energy Technology Data Exchange (ETDEWEB)

Wang, Gufeng; Stender, Anthony S.; Sun, Wei; and Fang, Ning

2009-12-17

Precise imaging of cellular and subcellular structures and dynamic processes in live cells is crucial for fundamental research in life sciences and in medical applications. Non-fluorescent nanoparticles are an important type of optical probe used in live-cell imaging due to their photostability, large optical cross-sections, and low toxicity. Here, we provide an overview of recent developments in the optical imaging of non-fluorescent nanoparticle probes in live cells.

Patch-based anisotropic diffusion scheme for fluorescence diffuse optical tomography--part 2: image reconstruction.

Science.gov (United States)

Correia, Teresa; Koch, Maximilian; Ale, Angelique; Ntziachristos, Vasilis; Arridge, Simon

2016-02-21

Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regularisation tends to either oversmooth or generate very noisy reconstructions, depending on the regularisation strength. Edge preserving methods, such as anisotropic diffusion regularisation (AD), can preserve important features in the fluorescence image and smooth out noise. However, AD has limited ability to distinguish an edge from noise. We propose a patch-based anisotropic diffusion regularisation (PAD), where regularisation strength is determined by a weighted average according to the similarity between patches around voxels within a search window, instead of a simple local neighbourhood strategy. However, this method has higher computational complexity and, hence, we wavelet compress the patches (PAD-WT) to speed it up, while simultaneously taking advantage of the denoising properties of wavelet thresholding. Furthermore, structural information can be incorporated into the image reconstruction with PAD-WT to improve image quality and resolution. In this case, the weights used to average voxels in the image are calculated using the structural image, instead of the fluorescence image. The regularisation strength depends on both structural and fluorescence images, which guarantees that the method can preserve fluorescence information even when it is not structurally visible in the anatomical images. In part 1, we tested the method using a denoising problem. Here, we use simulated and in vivo mouse fDOT data to assess the algorithm performance. Our results show that the proposed PAD-WT method provides high quality and noise free images, superior to those obtained using AD.

NONINVASIVE OPTICAL IMAGING OF STAPHYLOCOCCUS AUREUS INFECTION IN VIVO USING AN ANTIMICROBIAL PEPTIDE FRAGMENT BASED NEAR-INFRARED FLUORESCENT PROBES

Directory of Open Access Journals (Sweden)

CUICUI LIU

2013-07-01

Full Text Available The diagnosis of bacterial infections remains a major challenge in medicine. Optical imaging of bacterial infection in living animals is usually conducted with genetic reporters such as light-emitting enzymes or fluorescent proteins. However, there are many circumstances where genetic reporters are not applicable, and there is an urgent need for exogenous synthetic probes that can selectively target bacteria. Optical imaging of bacteria in vivo is much less developed than methods such as radioimaging and MRI. Furthermore near-infrared (NIR dyes with emission wavelengths in the region of 650–900 nm can propagate through two or more centimeters of tissue and may enable deeper tissue imaging if sensitive detection techniques are employed. Here we constructed an antimicrobial peptide fragment UBI29-41-based near-infrared fluorescent imaging probe. The probe is composed of UBI29-41 conjugated to a near infrared dye ICG-Der-02. UBI29-41 is a cationic antimicrobial peptide that targets the anionic surfaces of bacterial cells. The probe allows detection of Staphylococcus aureus infection (5 × 107 cells in a mouse local infection model using whole animal near-infrared fluorescence imaging. Furthermore, we demonstrate that the UBI29-41-based imaging probe can selectively accumulate within bacteria. The significantly higher accumulation in bacterial infection suggests that UBI29-41-based imaging probe may be a promising imaging agent to detect bacterial infections.

Three-dimensional in vivo fluorescence diffuse optical tomography of breast cancer in humans

Science.gov (United States)

Corlu, Alper; Choe, Regine; Durduran, Turgut; Rosen, Mark A.; Schweiger, Martin; Arridge, Simon R.; Schnall, Mitchell D.; Yodh, Arjun G.

2007-05-01

We present three-dimensional (3D) in vivo images of human breast cancer based on fluorescence diffuse optical tomography (FDOT). To our knowledge, this work represents the first reported 3D fluorescence tomography of human breast cancer in vivo. In our protocol, the fluorophore Indocyanine Green (ICG) is injected intravenously. Fluorescence excitation and detection are accomplished in the soft-compression, parallel-plane, transmission geometry using laser sources at 786 nm and spectrally filtered CCD detection. Phantom and in vivo studies confirm the signals are due to ICG fluorescence, rather than tissue autofluorescence and excitation light leakage. Fluorescence images of breast tumors were in good agreement with those of MRI, and with DOT based on endogenous contrast. Tumorto- normal tissue contrast based on ICG fluorescence was two-to-four-fold higher than contrast based on hemoglobin and scattering parameters. In total the measurements demonstrate that FDOT of breast cancer is feasible and promising.

Fluorescent nanohybrids based on asymmetrical cyanine dyes decorated carbon nanotubes

OpenAIRE

Çavuşlar, Özge; Cavuslar, Ozge

2015-01-01

In this thesis, we focused on imparting new optical properties to carbon nanotubes (CNTs) to allow their optical detection and visualization in biomedical applications. We investigated the interactions of CNTs and DNA wrapped CNTs with asymmetrical cyanine dye molecules to study the applicability of resulting hybrid materials to fluorescent based systems. When CNTs interacted with asymmetrical cyanine dyes, they constructed a light absorbing nanoarray. However, the fluorescence emission of th...

Multiplexed fluorescent microarray for human salivary protein analysis using polymer microspheres and fiber-optic bundles.

Science.gov (United States)

Nie, Shuai; Benito-Peña, Elena; Zhang, Huaibin; Wu, Yue; Walt, David R

2013-10-10

Herein, we describe a protocol for simultaneously measuring six proteins in saliva using a fiber-optic microsphere-based antibody array. The immuno-array technology employed combines the advantages of microsphere-based suspension array fabrication with the use of fluorescence microscopy. As described in the video protocol, commercially available 4.5 μm polymer microspheres were encoded into seven different types, differentiated by the concentration of two fluorescent dyes physically trapped inside the microspheres. The encoded microspheres containing surface carboxyl groups were modified with monoclonal capture antibodies through EDC/NHS coupling chemistry. To assemble the protein microarray, the different types of encoded and functionalized microspheres were mixed and randomly deposited in 4.5 μm microwells, which were chemically etched at the proximal end of a fiber-optic bundle. The fiber-optic bundle was used as both a carrier and for imaging the microspheres. Once assembled, the microarray was used to capture proteins in the saliva supernatant collected from the clinic. The detection was based on a sandwich immunoassay using a mixture of biotinylated detection antibodies for different analytes with a streptavidin-conjugated fluorescent probe, R-phycoerythrin. The microarray was imaged by fluorescence microscopy in three different channels, two for microsphere registration and one for the assay signal. The fluorescence micrographs were then decoded and analyzed using a homemade algorithm in MATLAB.

Distributed fluorescent optical fiber proximity sensor: Towards a proof of concept

Science.gov (United States)

Gălătuș, Ramona; Faragó, Paul; Miluski, Piotr; Valles, Juan-Antonio

2018-06-01

Fluorescent fibers are optical fibers which emit light as a response to an incident phenomenon, usually an incident light. Operation depends on the doping dyes, which determine specific fluorescence and optical characteristics useful in the development of optical sensors. In this work we propose a low-cost distributed proximity sensor implemented using a red fluorescent fiber, to provide a security option for a surface plasmon resonance system. Operation of the proposed sensor relies on having the incident illumination intensity varied by the presence or absence of an obstacle in the vicinity of the sensing element. This will influence the radiated fluorescence accordingly. The proposed setup for the implementation of the optical proximity sensor assumes having a high brightness LED deployed for axial fiber illumination and a blue LED for side illumination. Electronic processing then accounts for gain and digitization. Measurement results of the prototype validate the proposed concept.

Smart optical probes for near-infrared fluorescence imaging of Alzheimer's disease pathology

International Nuclear Information System (INIS)

Raymond, Scott B.; Bacskai, Brian J.; Skoch, Jesse; Hills, Ivory D.; Swager, Timothy M.; Nesterov, Evgueni E.

2008-01-01

Near-infrared fluorescent probes for amyloid-beta (Aβ) are an exciting option for molecular imaging in Alzheimer's disease research and may translate to clinical diagnostics. However, Aβ-targeted optical probes often suffer from poor specificity and slow clearance from the brain. We are designing smart optical probes that emit characteristic fluorescence signal only when bound to Aβ. We synthesized a family of dyes and tested Aβ-binding sensitivity with fluorescence spectroscopy and tissue-staining. Select compounds exhibited Aβ-dependent changes in fluorescence quantum yield, lifetime, and emission spectra that may be imaged microscopically or in vivo using new lifetime and spectral fluorescence imaging techniques. Smart optical probes that turn on when bound to Aβ will improve amyloid detection and may enable quantitative molecular imaging in vivo. (orig.)

Simultaneous differential spinning disk fluorescence optical sectioning microscopy and nanomechanical mapping atomic force microscopy

International Nuclear Information System (INIS)

Miranda, Adelaide; De Beule, Pieter A. A.; Martins, Marco

2015-01-01

Combined microscopy techniques offer the life science research community a powerful tool to investigate complex biological systems and their interactions. Here, we present a new combined microscopy platform based on fluorescence optical sectioning microscopy through aperture correlation microscopy with a Differential Spinning Disk (DSD) and nanomechanical mapping with an Atomic Force Microscope (AFM). The illumination scheme of the DSD microscope unit, contrary to standard single or multi-point confocal microscopes, provides a time-independent illumination of the AFM cantilever. This enables a distortion-free simultaneous operation of fluorescence optical sectioning microscopy and atomic force microscopy with standard probes. In this context, we discuss sample heating due to AFM cantilever illumination with fluorescence excitation light. Integration of a DSD fluorescence optical sectioning unit with an AFM platform requires mitigation of mechanical noise transfer of the spinning disk. We identify and present two solutions to almost annul this noise in the AFM measurement process. The new combined microscopy platform is applied to the characterization of a DOPC/DOPS (4:1) lipid structures labelled with a lipophilic cationic indocarbocyanine dye deposited on a mica substrate

Simultaneous differential spinning disk fluorescence optical sectioning microscopy and nanomechanical mapping atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Miranda, Adelaide; De Beule, Pieter A. A., E-mail: pieter.de-beule@inl.int [Applied Nano-Optics Laboratory, International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, s/n, 4715-330 Braga (Portugal); Martins, Marco [Nano-ICs Group, International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, s/n, 4715-330 Braga (Portugal)

2015-09-15

Combined microscopy techniques offer the life science research community a powerful tool to investigate complex biological systems and their interactions. Here, we present a new combined microscopy platform based on fluorescence optical sectioning microscopy through aperture correlation microscopy with a Differential Spinning Disk (DSD) and nanomechanical mapping with an Atomic Force Microscope (AFM). The illumination scheme of the DSD microscope unit, contrary to standard single or multi-point confocal microscopes, provides a time-independent illumination of the AFM cantilever. This enables a distortion-free simultaneous operation of fluorescence optical sectioning microscopy and atomic force microscopy with standard probes. In this context, we discuss sample heating due to AFM cantilever illumination with fluorescence excitation light. Integration of a DSD fluorescence optical sectioning unit with an AFM platform requires mitigation of mechanical noise transfer of the spinning disk. We identify and present two solutions to almost annul this noise in the AFM measurement process. The new combined microscopy platform is applied to the characterization of a DOPC/DOPS (4:1) lipid structures labelled with a lipophilic cationic indocarbocyanine dye deposited on a mica substrate.

Monitoring scaling and dental calculus removal with an optical fluorescence system

International Nuclear Information System (INIS)

Sivieri-Araujo, G; Fontana, C R; Costa, M M; Kurachi, C; Bagnato, V S; Rastelli, A N S; Pereira, L P C

2014-01-01

Fluorescence results from a process that occurs under certain conditions in molecules known as fluorophores, fluorochromes or fluorescent dyes when they absorb light. The molecule is excited to a higher energy state and emits fluorescent light. The emission wavelength is always higher than the excitation wavelength. Optical diagnoses by fluorescence can be used in medicine and dentistry. It does not cause injury to tissues because it is a noninvasive method and can add benefits to clinical treatments. The aim of this case report was to apply an optical fluorescence system for wide-field image viewing and visual monitoring of the management of plaque and dental calculus before and after periodontal scaling to improve the diagnoses and follow-up of patients with periodontal disease. The results suggest that it is possible to observe, with a fluorescence system, residual plaque and calculus that were not easily seen by the naked eye during oral inspection. Thus, the optical technique can potentially improve periodontal screening efforts, especially in patients undergoing periodontal maintenance. (paper)

Monitoring scaling and dental calculus removal with an optical fluorescence system

Science.gov (United States)

Sivieri-Araujo, G.; Fontana, C. R.; Costa, M. M.; Rastelli, A. N. S.; Pereira, L. P. C.; Kurachi, C.; Bagnato, V. S.

2014-08-01

Fluorescence results from a process that occurs under certain conditions in molecules known as fluorophores, fluorochromes or fluorescent dyes when they absorb light. The molecule is excited to a higher energy state and emits fluorescent light. The emission wavelength is always higher than the excitation wavelength. Optical diagnoses by fluorescence can be used in medicine and dentistry. It does not cause injury to tissues because it is a noninvasive method and can add benefits to clinical treatments. The aim of this case report was to apply an optical fluorescence system for wide-field image viewing and visual monitoring of the management of plaque and dental calculus before and after periodontal scaling to improve the diagnoses and follow-up of patients with periodontal disease. The results suggest that it is possible to observe, with a fluorescence system, residual plaque and calculus that were not easily seen by the naked eye during oral inspection. Thus, the optical technique can potentially improve periodontal screening efforts, especially in patients undergoing periodontal maintenance.

A fusion-spliced near-field optical fiber probe using photonic crystal fiber for nanoscale thermometry based on fluorescence-lifetime measurement of quantum dots.

Science.gov (United States)

Fujii, Takuro; Taguchi, Yoshihiro; Saiki, Toshiharu; Nagasaka, Yuji

2011-01-01

We have developed a novel nanoscale temperature-measurement method using fluorescence in the near-field called fluorescence near-field optics thermal nanoscopy (Fluor-NOTN). Fluor-NOTN enables the temperature distributions of nanoscale materials to be measured in vivo/in situ. The proposed method measures temperature by detecting the temperature dependent fluorescence lifetimes of Cd/Se quantum dots (QDs). For a high-sensitivity temperature measurement, the auto-fluorescence generated from a fiber probe should be reduced. In order to decrease the noise, we have fabricated a novel near-field optical-fiber probe by fusion-splicing a photonic crystal fiber (PCF) and a conventional single-mode fiber (SMF). The validity of the novel fiber probe was assessed experimentally by evaluating the auto-fluorescence spectra of the PCF. Due to the decrease of auto-fluorescence, a six- to ten-fold increase of S/N in the near-field fluorescence lifetime detection was achieved with the newly fabricated fusion-spliced near-field optical fiber probe. Additionally, the near-field fluorescence lifetime of the quantum dots was successfully measured by the fabricated fusion-spliced near-field optical fiber probe at room temperature, and was estimated to be 10.0 ns.

Optical imaging as an expansion of nuclear medicine: Cerenkov-based luminescence vs fluorescence-based luminescence

International Nuclear Information System (INIS)

Chin, Patrick T.K.; Welling, Mick M.; Leeuwen, Fijs W.B. van; Meskers, Stefan C.J.; Valdes Olmos, Renato A.; Tanke, Hans

2013-01-01

Integration of optical imaging technologies can further strengthen the field of radioguided surgery. Rather than using two separate chemical entities to achieve this extension, hybrid imaging agents can be used that contain both radionuclear and optical properties. Two types of such hybrid imaging agents are available: (1) hybrid imaging agents generated by Cerenkov luminescence imaging (CLI) of β-emitters and (2) hybrid imaging agents that contain both a radioactive moiety and a fluorescent dye. One major challenge clinicians are now facing is to determine the potential value of these approaches. With this tutorial review we intend to clarify the differences between the two approaches and highlight the clinical potential of hybrid imaging during image-guided surgery applications. (orig.)

Optical imaging as an expansion of nuclear medicine: Cerenkov-based luminescence vs fluorescence-based luminescence

Energy Technology Data Exchange (ETDEWEB)

Chin, Patrick T.K.; Welling, Mick M.; Leeuwen, Fijs W.B. van [Leiden University Medical Center, Interventional Molecular Imaging Laboratory, Department of Radiology, P.O. Box 9600, Leiden (Netherlands); Meskers, Stefan C.J. [Eindhoven University of Technology, Molecular Materials and Nanosystems, P.O. Box 513, Eindhoven (Netherlands); Valdes Olmos, Renato A. [Leiden University Medical Center, Interventional Molecular Imaging Laboratory, Department of Radiology, P.O. Box 9600, Leiden (Netherlands); Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Department of Nuclear Medicine, Amsterdam (Netherlands); Tanke, Hans [Leiden University Medical Center, Department of Molecular Cell Biology, P.O. Box 9600, Leiden (Netherlands)

2013-08-15

Integration of optical imaging technologies can further strengthen the field of radioguided surgery. Rather than using two separate chemical entities to achieve this extension, hybrid imaging agents can be used that contain both radionuclear and optical properties. Two types of such hybrid imaging agents are available: (1) hybrid imaging agents generated by Cerenkov luminescence imaging (CLI) of {beta}-emitters and (2) hybrid imaging agents that contain both a radioactive moiety and a fluorescent dye. One major challenge clinicians are now facing is to determine the potential value of these approaches. With this tutorial review we intend to clarify the differences between the two approaches and highlight the clinical potential of hybrid imaging during image-guided surgery applications. (orig.)

Amplification of the Signal Intensity of Fluorescence-Based Fiber-Optic Biosensors Using a Fabry-Perot Resonator Structure

Directory of Open Access Journals (Sweden)

Meng-Chang Hsieh

2015-02-01

Full Text Available Fluorescent biosensors have been widely used in biomedical applications. To amplify the intensity of fluorescence signals, this study developed a novel structure for an evanescent wave fiber-optic biosensor by using a Fabry-Perot resonator structure. An excitation light was coupled into the optical fiber through a laser-drilled hole on the proximal end of the resonator. After entering the resonator, the excitation light was reflected back and forth inside the resonator, thereby amplifying the intensity of the light in the fiber. Subsequently, the light was used to excite the fluorescent molecules in the reactive region of the sensor. The experimental results showed that the biosensor signal was amplified eight-fold when the resonator reflector was formed using a 92% reflective coating. Furthermore, in a simulation, the biosensor signal could be amplified 20-fold by using a 99% reflector.

Optical tweezers and non-ratiometric fluorescent-dye-based studies of respiration in sperm mitochondria

International Nuclear Information System (INIS)

Chen, Timothy; Shi, Linda Z; Zhu, Qingyuan; Chandsawangbhuwana, Charlie; Berns, Michael W

2011-01-01

The purpose of this study is to investigate how the mitochondrial membrane potential affects sperm motility using laser tweezers and a non-ratiometric fluorescent probe, DiOC 6 (3). A 1064 nm Nd:YVO4 continuous wave laser was used to trap motile sperm at a power of 450 mW in the trap spot. Using customized tracking software, the curvilinear velocity (VCL) and the escape force from the laser tweezers were measured. Human (Homo sapiens), dog (Canis lupis familiaris) and drill (Mandrillus leucophaeus) sperm were treated with DiOC 6 (3) to measure the membrane potential in the mitochondria-rich sperm midpieces. Sperm from all three species exhibited an increase in fluorescence when treated with the DiOC 6 (3). When a cyanide inhibitor (CCCP) of aerobic respiration was applied, sperm of all three species exhibited a reduction in fluorescence to pre-dye levels. With respect to VCL and escape force, the CCCP had no effect on dog or human sperm, suggesting a major reliance upon anaerobic respiration (glycolysis) for ATP in these two species. Based on the preliminary study on drill sperm, CCCP caused a drop in the VCL, suggesting potential reliance on both glycolysis and aerobic respiration for motility. The results demonstrate that optical trapping in combination with DiOC 6 (3) is an effective way to study sperm motility and energetics

Optical tweezers and non-ratiometric fluorescent-dye-based studies of respiration in sperm mitochondria

Science.gov (United States)

Chen, Timothy; Shi, Linda Z.; Zhu, Qingyuan; Chandsawangbhuwana, Charlie; Berns, Michael W.

2011-04-01

The purpose of this study is to investigate how the mitochondrial membrane potential affects sperm motility using laser tweezers and a non-ratiometric fluorescent probe, DiOC6(3). A 1064 nm Nd:YVO4 continuous wave laser was used to trap motile sperm at a power of 450 mW in the trap spot. Using customized tracking software, the curvilinear velocity (VCL) and the escape force from the laser tweezers were measured. Human (Homo sapiens), dog (Canis lupis familiaris) and drill (Mandrillus leucophaeus) sperm were treated with DiOC6(3) to measure the membrane potential in the mitochondria-rich sperm midpieces. Sperm from all three species exhibited an increase in fluorescence when treated with the DiOC6(3). When a cyanide inhibitor (CCCP) of aerobic respiration was applied, sperm of all three species exhibited a reduction in fluorescence to pre-dye levels. With respect to VCL and escape force, the CCCP had no effect on dog or human sperm, suggesting a major reliance upon anaerobic respiration (glycolysis) for ATP in these two species. Based on the preliminary study on drill sperm, CCCP caused a drop in the VCL, suggesting potential reliance on both glycolysis and aerobic respiration for motility. The results demonstrate that optical trapping in combination with DiOC6(3) is an effective way to study sperm motility and energetics.

Fluorescent molecularly imprinted polymer based on Navicula sp. frustules for optical detection of lysozyme.

Science.gov (United States)

Lim, Guat Wei; Lim, Jit Kang; Ahmad, Abdul Latif; Chan, Derek Juinn Chieh

2016-03-01

The direct correlation between disease and lysozyme (LYZ) levels in human body fluids makes the sensitive and convenient detection of LYZ the focus of scientific research. Fluorescent molecularly imprinted polymer has emerged as a new alternative for LYZ detection in order to resolve the limitation of immunoassays, which are expensive, unstable, require complex preparation, and are time consuming. In this study, a novel fluorescence molecularly imprinted polymer based on Navicula sp. frustules (FITC-MIP) has been synthesized via post-imprinting treatment for LYZ detection. Navicula sp. frustules were used as supported material because of their unique properties of moderate surface area, reproducibility, and biocompatibility, to address the drawbacks of nanoparticle core material with low adsorption capacity. The FITC acts as recognition signal and optical readout, whereas MIP provides LYZ selectivity. The synthesized FITC-MIP showed a response time as short as 5 min depending on the concentration of LYZ. It is found that the LYZ template can significantly quench the fluorescence intensity of FITC-MIP linearly within a concentration range of 0 to 0.025 mg mL(-1), which is well described by Stern-Volmer equation. The FITC-MIP can selectively and sensitively detect down to 0.0015 mg mL(-1) of LYZ concentration. The excellent sensing performance of FITC-MIP suggests that FITC-MIP is a potential biosensor in clinical diagnosis applications.

State-dependent fluorescence of neutral atoms in optical potentials

Science.gov (United States)

Martinez-Dorantes, M.; Alt, W.; Gallego, J.; Ghosh, S.; Ratschbacher, L.; Meschede, D.

2018-02-01

Recently we have demonstrated scalable, nondestructive, and high-fidelity detection of the internal state of 87Rb neutral atoms in optical dipole traps using state-dependent fluorescence imaging [M. Martinez-Dorantes, W. Alt, J. Gallego, S. Ghosh, L. Ratschbacher, Y. Völzke, and D. Meschede, Phys. Rev. Lett. 119, 180503 (2017), 10.1103/PhysRevLett.119.180503]. In this paper we provide experimental procedures and interpretations to overcome the detrimental effects of heating-induced trap losses and state leakage. We present models for the dynamics of optically trapped atoms during state-dependent fluorescence imaging and verify our results by comparing Monte Carlo simulations with experimental data. Our systematic study of dipole force fluctuations heating in optical traps during near-resonant illumination shows that off-resonant light is preferable for state detection in tightly confining optical potentials.

Laser-based optical detection of explosives

CERN Document Server

Pellegrino, Paul M; Farrell, Mikella E

2015-01-01

Laser-Based Optical Detection of Explosives offers a comprehensive review of past, present, and emerging laser-based methods for the detection of a variety of explosives. This book: Considers laser propagation safety and explains standard test material preparation for standoff optical-based detection system evaluation Explores explosives detection using deep ultraviolet native fluorescence, Raman spectroscopy, laser-induced breakdown spectroscopy, reflectometry, and hyperspectral imaging Examines photodissociation followed by laser-induced fluorescence, photothermal methods, cavity-enhanced absorption spectrometry, and short-pulse laser-based techniques Describes the detection and recognition of explosives using terahertz-frequency spectroscopic techniques Each chapter is authored by a leading expert on the respective technology, and is structured to supply historical perspective, address current advantages and challenges, and discuss novel research and applications. Readers are left with an in-depth understa...

Piezoresistor-equipped fluorescence-based cantilever probe for near-field scanning.

Science.gov (United States)

Kan, Tetsuo; Matsumoto, Kiyoshi; Shimoyama, Isao

2007-08-01

Scanning near-field optical microscopes (SNOMs) with fluorescence-based probes are promising tools for evaluating the optical characteristics of nanoaperture devices used for biological investigations, and this article reports on the development of a microfabricated fluorescence-based SNOM probe with a piezoresistor. The piezoresistor was built into a two-legged root of a 160-microm-long cantilever. To improve the displacement sensitivity of the cantilever, the piezoresistor's doped area was shallowly formed on the cantilever surface. A fluorescent bead, 500 nm in diameter, was attached to the bottom of the cantilever end as a light-intensity-sensitive material in the visible-light range. The surface of the scanned sample was simply detected by the probe's end being displaced by contact with the sample. Measuring displacements piezoresistively is advantageous because it eliminates the noise arising from the use of the optical-lever method and is free of any disturbance in the absorption or the emission spectrum of the fluorescent material at the probe tip. The displacement sensitivity was estimated to be 6.1 x 10(-6) nm(-1), and the minimum measurable displacement was small enough for near-field measurement. This probe enabled clear scanning images of the light field near a 300 x 300 nm(2) aperture to be obtained in the near-field region where the tip-sample distance is much shorter than the light wavelength. This scanning result indicates that the piezoresistive way of tip-sample distance regulation is effective for characterizing nanoaperture optical devices.

Preclinical, fluorescence and diffuse optical tomography: non-contact instrumentation, modeling and time-resolved 3D reconstruction

International Nuclear Information System (INIS)

Nouizi, F.

2011-09-01

Time-Resolved Diffuse Optical Tomography (TR-DOT) is a new non-invasive imaging technique increasingly used in the clinical and preclinical fields. It yields optical absorption and scattering maps of the explored organs, and related physiological parameters. Time-Resolved Fluorescence Diffuse Optical Tomography (TR-FDOT) is based on the detection of fluorescence photons. It provides spatio-temporal maps of fluorescent probe concentrations and life times, and allows access to metabolic and molecular imaging which is important for diagnosis and therapeutic monitoring, particularly in oncology. The main goal of this thesis was to reconstruct 3D TR-DOT/TR-FDOT images of small animals using time-resolved optical technology. Data were acquired using optical fibers fixed around the animal without contact with its surface. The work was achieved in four steps: 1)- Setting up an imaging device to record the 3D coordinates of an animal's surface; 2)- Modeling the no-contact approach to solve the forward problem; 3)- Processing of the measured signals taking into account the impulse response of the device; 4)- Implementation of a new image reconstruction method based on a selection of carefully chosen points. As a result, good-quality 3D optical images were obtained owing to reduced cross-talk between absorption and scattering. Moreover, the computation time was cut down, compared to full-time methods using whole temporal profiles. (author)

Enhanced-locality fiber-optic two-photon-fluorescence live-brain interrogation

Energy Technology Data Exchange (ETDEWEB)

Fedotov, I. V.; Doronina-Amitonova, L. V. [International Laser Center, Physics Department, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 1430125 (Russian Federation); Kurchatov Institute National Research Center, Moscow (Russian Federation); Sidorov-Biryukov, D. A.; Fedotov, A. B. [International Laser Center, Physics Department, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 1430125 (Russian Federation); Anokhin, K. V. [Kurchatov Institute National Research Center, Moscow (Russian Federation); P.K. Anokhin Institute of Normal Physiology, Russian Academy of Medical Sciences, Moscow (Russian Federation); Kilin, S. Ya. [B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk (Belarus); Sakoda, K. [National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan); Zheltikov, A. M. [International Laser Center, Physics Department, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Russian Quantum Center, ul. Novaya 100, Skolkovo, Moscow Region 1430125 (Russian Federation); Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States); Center of Photochemistry, Russian Academy of Sciences, ul. Novatorov 7a, Moscow 117421 (Russian Federation)

2014-02-24

Two-photon excitation is shown to substantially enhance the locality of fiber-based optical interrogation of strongly scattering biotissues. In our experiments, a high-numerical-aperture, large-core-are fiber probe is used to deliver the 200-fs output of a 100-MHz mode-locked ytterbium fiber laser to samples of live mouse brain, induce two-photon fluorescence of nitrogen–vacancy centers in diamond markers in brain sample. Fiber probes with a high numerical aperture and a large core area are shown to enable locality enhancement in fiber-laser–fiber-probe two-photon brain excitation and interrogation without sacrificing the efficiency of fluorescence response collection.

Nonmydriatic fluorescence-based quantitative imaging of human macular pigment distributions

Science.gov (United States)

Sharifzadeh, Mohsen; Bernstein, Paul S.; Gellermann, Werner

2006-10-01

We have developed a CCD-camera-based nonmydriatic instrument that detects fluorescence from retinal lipofuscin chromophores ("autofluorescence") as a means to indirectly quantify and spatially image the distribution of macular pigment (MP). The lipofuscin fluorescence intensity is reduced at all retinal locations containing MP, since MP has a competing absorption in the blue-green wavelength region. Projecting a large diameter, 488 nm excitation spot onto the retina, centered on the fovea, but extending into the macular periphery, and comparing lipofuscin fluorescence intensities outside and inside the foveal area, it is possible to spatially map out the distribution of MP. Spectrally selective detection of the lipofuscin fluorescence reveals an important wavelength dependence of the obtainable image contrast and deduced MP optical density levels, showing that it is important to block out interfering fluorescence contributions in the detection setup originating from ocular media such as the lens. Measuring 70 healthy human volunteer subjects with no ocular pathologies, we find widely varying spatial extent of MP, distinctly differing distribution patterns of MP, and strongly differing absolute MP levels among individuals. Our population study suggests that MP imaging based on lipofuscin fluorescence is useful as a relatively simple, objective, and quantitative noninvasive optical technique suitable to rapidly screen MP levels and distributions in healthy humans with undilated pupils.

Characterization of a confocal three-dimensional micro X-ray fluorescence facility based on polycapillary X-ray optics and Kirkpatrick-Baez mirrors

International Nuclear Information System (INIS)

Sun Tianxi; Ding Xunliang; Liu Zhiguo; Zhu Guanghua; Li Yude; Wei Xiangjun; Chen Dongliang; Xu Qing; Liu Quanru; Huang Yuying; Lin Xiaoyan; Sun Hongbo

2008-01-01

A new confocal three-dimensional micro X-ray fluorescence (3D micro-XRF) facility based on polycapillary X-ray optics in the detection channel and Kirkpatrick-Baez (KB) mirrors in the excitation channel is designed. The lateral resolution (l x , l y ) of this confocal three-dimensional micro-X-ray fluorescence facility is 76.3(l x ) and 53.4(l y ) μm respectively, and its depth resolution d z is 77.1 μm at θ = 90 o . A plant sample (twig of B. microphylla) and airborne particles are analyzed

Near-infrared emitting fluorescent nanocrystals-labeled natural killer cells as a platform technology for the optical imaging of immunotherapeutic cells-based cancer therapy

International Nuclear Information System (INIS)

Lim, Yong Taik; Cho, Mi Young; Noh, Young-Woock; Chung, Bong Hyun; Chung, Jin Woong

2009-01-01

This study describes the development of near-infrared optical imaging technology for the monitoring of immunotherapeutic cell-based cancer therapy using natural killer (NK) cells labeled with fluorescent nanocrystals. Although NK cell-based immunotherapeutic strategies have drawn interest as potent preclinical or clinical methods of cancer therapy, there are few reports documenting the molecular imaging of NK cell-based cancer therapy, primarily due to the difficulty of labeling of NK cells with imaging probes. Human natural killer cells (NK92MI) were labeled with anti-human CD56 antibody-coated quantum dots (QD705) for fluorescence imaging. FACS analysis showed that the NK92MI cells labeled with anti-human CD56 antibody-coated QD705 have no effect on the cell viability. The effect of anti-human CD56 antibody-coated QD705 labeling on the NK92MI cell function was investigated by measuring interferon gamma (IFN- γ) production and cytolytic activity. Finally, the NK92MI cells labeled with anti-human CD56 antibody-coated QD705 showed a therapeutic effect similar to that of unlabeled NK92MI cells. Images of intratumorally injected NK92MI cells labeled with anti-human CD56 antibody-coated could be acquired using near-infrared optical imaging both in vivo and in vitro. This result demonstrates that the immunotherapeutic cells labeled with fluorescent nanocrystals can be a versatile platform for the effective tracking of injected therapeutic cells using optical imaging technology, which is very important in cell-based cancer therapies.

In-vivo optical detection of cancer using chlorin e6 – polyvinylpyrrolidone induced fluorescence imaging and spectroscopy

International Nuclear Information System (INIS)

Chin, William WL; Thong, Patricia SP; Bhuvaneswari, Ramaswamy; Soo, Khee Chee; Heng, Paul WS; Olivo, Malini

2009-01-01

Photosensitizer based fluorescence imaging and spectroscopy is fast becoming a promising approach for cancer detection. The purpose of this study was to examine the use of the photosensitizer chlorin e6 (Ce6) formulated in polyvinylpyrrolidone (PVP) as a potential exogenous fluorophore for fluorescence imaging and spectroscopic detection of human cancer tissue xenografted in preclinical models as well as in a patient. Fluorescence imaging was performed on MGH human bladder tumor xenografted on both the chick chorioallantoic membrane (CAM) and the murine model using a fluorescence endoscopy imaging system. In addition, fiber optic based fluorescence spectroscopy was performed on tumors and various normal organs in the same mice to validate the macroscopic images. In one patient, fluorescence imaging was performed on angiosarcoma lesions and normal skin in conjunction with fluorescence spectroscopy to validate Ce6-PVP induced fluorescence visual assessment of the lesions. Margins of tumor xenografts in the CAM model were clearly outlined under fluorescence imaging. Ce6-PVP-induced fluorescence imaging yielded a specificity of 83% on the CAM model. In mice, fluorescence intensity of Ce6-PVP was higher in bladder tumor compared to adjacent muscle and normal bladder. Clinical results confirmed that fluorescence imaging clearly captured the fluorescence of Ce6-PVP in angiosarcoma lesions and good correlation was found between fluorescence imaging and spectral measurement in the patient. Combination of Ce6-PVP induced fluorescence imaging and spectroscopy could allow for optical detection and discrimination between cancer and the surrounding normal tissues. Ce6-PVP seems to be a promising fluorophore for fluorescence diagnosis of cancer

Polymer optical fiber compound parabolic concentrator tip for enhanced coupling efficiency for fluorescence based glucose sensors

DEFF Research Database (Denmark)

Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Søren

2015-01-01

We demonstrate that the light excitation and capturing efficiency of fluorescence based fiber-optical sensors can be significantly increased by using a CPC (Compound Parabolic Concentrator) tip instead of the standard plane-cut tip. We use Zemax modelling to find the optimum CPC tip profile...... and fiber length of a polymer optical fiber diabetes sensor for continuous monitoring of glucose levels. We experimentally verify the improved performance of the CPC tipped sensor and the predicted production tolerances. Due to physical size requirements when the sensor has to be inserted into the body...... a non-optimal fiber length of 35 mm is chosen. For this length an average improvement in efficiency of a factor of 1.7 is experimentally demonstrated and critically compared to the predicted ideal factor of 3 in terms of parameters that should be improved through production optimization....

Polymer optical fiber compound parabolic concentrator tip for enhanced coupling efficiency for fluorescence based glucose sensors.

Science.gov (United States)

Hassan, Hafeez Ul; Nielsen, Kristian; Aasmul, Soren; Bang, Ole

2015-12-01

We demonstrate that the light excitation and capturing efficiency of fluorescence based fiber-optical sensors can be significantly increased by using a CPC (Compound Parabolic Concentrator) tip instead of the standard plane-cut tip. We use Zemax modelling to find the optimum CPC tip profile and fiber length of a polymer optical fiber diabetes sensor for continuous monitoring of glucose levels. We experimentally verify the improved performance of the CPC tipped sensor and the predicted production tolerances. Due to physical size requirements when the sensor has to be inserted into the body a non-optimal fiber length of 35 mm is chosen. For this length an average improvement in efficiency of a factor of 1.7 is experimentally demonstrated and critically compared to the predicted ideal factor of 3 in terms of parameters that should be improved through production optimization.

Patch-based anisotropic diffusion scheme for fluorescence diffuse optical tomography—part 1: technical principles

International Nuclear Information System (INIS)

Correia, Teresa; Arridge, Simon

2016-01-01

Fluorescence diffuse optical tomography (fDOT) provides 3D images of fluorescence distributions in biological tissue, which represent molecular and cellular processes. The image reconstruction problem is highly ill-posed and requires regularisation techniques to stabilise and find meaningful solutions. Quadratic regularisation tends to either oversmooth or generate very noisy reconstructions, depending on the regularisation strength. Edge preserving methods, such as anisotropic diffusion regularisation (AD), can preserve important features in the fluorescence image and smooth out noise. However, AD has limited ability to distinguish an edge from noise. In this two-part paper, we propose a patch-based anisotropic diffusion regularisation (PAD), where regularisation strength is determined by a weighted average according to the similarity between patches around voxels within a search window, instead of a simple local neighbourhood strategy. However, this method has higher computational complexity and, hence, we wavelet compress the patches (PAD-WT) to speed it up, while simultaneously taking advantage of the denoising properties of wavelet thresholding. The proposed method combines the nonlocal means (NLM), AD and wavelet shrinkage methods, which are image processing methods. Therefore, in this first paper, we used a denoising test problem to analyse the performance of the new method. Our results show that the proposed PAD-WT method provides better results than the AD or NLM methods alone. The efficacy of the method for fDOT image reconstruction problem is evaluated in part 2. (paper)

A fluorescent optical fibre chemosensor for mercury detection

Science.gov (United States)

Wren, Stephen P.; Sun, Tong; Grattan, Kenneth T. V.

2015-09-01

A proof-of-concept mercury probe was developed based on covalent attachment of a chemical coating to optical fibre. The sensing element comprised a dansyl derivative and crown ether moiety, acting as fluorophore and metal ion chelator respectively. An ON-OFF type fluorescence (quench) occurred upon binding of mercury ions, via an intramolecular charge transfer mechanism, in aqueous solution in the 909nM-90.9μM (247 ppb -24.7 ppm) concentration range. A washing protocol was identified for sensor regeneration allowing the probe to be re-used.

Integrated Micro-Optical Fluorescence Detection System for Microfluidic Electrochromatography

International Nuclear Information System (INIS)

ALLERMAN, ANDREW A.; ARNOLD, DON W.; ASBILL, RANDOLPH E.; BAILEY, CHRISTOPHER G.; CARTER, TONY RAY; KEMME, SHANALYN A.; MATZKE, CAROLYN M.; SAMORA, SALLY; SWEATT, WILLIAM C.; WARREN, MIAL E.; WENDT, JOEL R.

1999-01-01

The authors describe the design and microfabrication of an extremely compact optical system as a key element in an integrated capillary-channel electrochromatograph with laser induced fluorescence detection. The optical design uses substrate-mode propagation within the fused silica substrate. The optical system includes a vertical cavity surface-emitting laser (VCSEL) array, two high performance microlenses and a commercial photodetector. The microlenses are multilevel diffractive optics patterned by electron beam lithography and etched by reactive ion etching in fused silica. Two generations of optical subsystems are described. The first generation design is integrated directly onto the capillary channel-containing substrate with a 6 mm separation between the VCSEL and photodetector. The second generation design separates the optical system onto its own module and the source to detector length is further compressed to 3.5 mm. The systems are designed for indirect fluorescence detection using infrared dyes. The first generation design has been tested with a 750 nm VCSEL exciting a 10(sup -4) M solution of CY-7 dye. The observed signal-to-noise ratio of better than 100:1 demonstrates that the background signal from scattered pump light is low despite the compact size of the optical system and meets the system sensitivity requirements

Intravital Fluorescence Excitation in Whole-Animal Optical Imaging.

Science.gov (United States)

Nooshabadi, Fatemeh; Yang, Hee-Jeong; Bixler, Joel N; Kong, Ying; Cirillo, Jeffrey D; Maitland, Kristen C

2016-01-01

Whole-animal fluorescence imaging with recombinant or fluorescently-tagged pathogens or cells enables real-time analysis of disease progression and treatment response in live animals. Tissue absorption limits penetration of fluorescence excitation light, particularly in the visible wavelength range, resulting in reduced sensitivity to deep targets. Here, we demonstrate the use of an optical fiber bundle to deliver light into the mouse lung to excite fluorescent bacteria, circumventing tissue absorption of excitation light in whole-animal imaging. We present the use of this technology to improve detection of recombinant reporter strains of tdTomato-expressing Mycobacterium bovis BCG (Bacillus Calmette Guerin) bacteria in the mouse lung. A microendoscope was integrated into a whole-animal fluorescence imager to enable intravital excitation in the mouse lung with whole-animal detection. Using this technique, the threshold of detection was measured as 103 colony forming units (CFU) during pulmonary infection. In comparison, the threshold of detection for whole-animal fluorescence imaging using standard epi-illumination was greater than 106 CFU.

A fiber-optic sorbitol biosensor based on NADH fluorescence detection toward rapid diagnosis of diabetic complications.

Science.gov (United States)

Gessei, Tomoko; Arakawa, Takahiro; Kudo, Hiroyuki; Mitsubayashi, Kohji

2015-09-21

Accumulation of sorbitol in the tissue is known to cause microvascular diabetic complications. In this paper, a fiber-optic biosensor for sorbitol which is used as a biomarker of diabetic complications was developed and tested. The biosensor used a sorbitol dehydrogenase from microorganisms of the genus Flavimonas with high substrate specificity and detected the fluorescence of reduced nicotinamide adenine dinucleotide (NADH) by the enzymatic reaction. An ultraviolet light emitting diode (UV-LED) was used as the excitation light source of NADH. The fluorescence of NADH was detected using a spectrometer or a photomultiplier tube (PMT). The UV-LED and the photodetector were coupled using a Y-shaped optical fiber. In the experiment, an optical fiber probe with a sorbitol dehydrogenase immobilized membrane was placed in a cuvette filled with a phosphate buffer containing the oxidized form of nicotinamide adenine dinucleotide (NAD(+)). The changes in NADH fluorescence intensity were measured after adding a standard sorbitol solution. According to the experimental assessment, the calibration range of the sorbitol biosensor systems using a spectrometer and a PMT was 5.0-1000 μmol L(-1) and 1.0-1000 μmol L(-1), respectively. The sorbitol biosensor system using the sorbitol dehydrogenase from microorganisms of the genus Flavimonas has high selectivity and sensitivity compared with that from sheep liver. The sorbitol biosensor allows for point-of-care testing applications or daily health care tests for diabetes patients.

A simple optical fiber device for quantitative fluorescence microscopy of single living cells

OpenAIRE

van Graft, M.; van Graft, Marja; Oosterhuis, B.; Oosterhuis, Bernard; van der Werf, Kees; de Grooth, B.G.; Greve, Jan

1993-01-01

simple and relatively inexpensive system is described for obtaining quantitative fluorescence measurements on single living cells loaded with a fluorescent probe to study cell physiological processes. The light emitted from the fluorescent cells is captured by and transported through an optical fiber. After passage through appropriate filters the light is measured using a photomultiplier tube. The optical fiber is mounted in one of the microscope outlets. Signals derived from the photomultipl...

Fluorescence diffuse optical tomography: benefits of using the time-resolved modality

International Nuclear Information System (INIS)

Ducros, Nicolas

2009-01-01

Fluorescence diffuse optical tomography enables the three-dimensional reconstruction of fluorescence markers injected within a biological tissue, with light in the near infrared range. The simple continuous modality uses steady excitation light and operates from the measurements at different positions of the attenuation of the incident beam. This technique is low-cost, non-ionizing, and easy to handle, but subject to low resolution for thick tissues due to diffusion. Hopefully, the time-resolved modality, which provides the time of flight of any detected photon, could overcome this limitation and pave the way to clinical applications. This thesis aims at determining the best way to exploit the time resolved information and at quantifying the advantages of this modality over the standard continuous wave one. Model deviations must be carefully limited when ill-posed problems as fluorescence diffuse optical tomography are considered. As a result, we have first addressed the modelling part of the problem. We have shown that the photons density models to good approximation the measurable quantity that is the quantity measured by an actual acquisition set-up. Then, the moment-based reconstruction scheme has been thoroughly evaluated by means of a theoretical analysis of the moments properties. It was found that the moment-based approach requires high photon counts to be profitable compared to the continuous wave modality. Last, a novel wavelet-based approach, which enables an improved reconstruction quality, has been introduced. This approach has shown good ability to exploit the temporal information at lower photon counts. (author) [fr

Development of a Novel Fiber Optic Sensor Combined with a Fluorescence Turn-on Probe for Cu (II Detection

Directory of Open Access Journals (Sweden)

Ma J.

2013-04-01

Full Text Available Existing staining-based methodology for the detection of metal ions is not well suited for real-time or in situ use. This is a significant problem, given that these ions can have a considerable impact on both human health and the environment. Thus, there is growing interest and need for simple, rapid and in-situ monitoring techniques for the purpose of detecting various target analytes (e.g. heavy metals, which is of a significant importance in many fields ranging from environmental monitoring to the study of intracellular processes. Among various sensors developed, optical fiber-optic sensors (FOS, based on fluorescence, are one class of sensors that address this goal [1]. Optical fibers are ideal for environmental sensing applications because of their ability to transmit optical signals to and from the sensing region without the use of free-space optics. In this work, we present, for the first time, a simple FOS incorporating novel fluorescence turn-on mechanism [2] that could detect Cu (II as low as 10−4 M. Traditionally, fluorescence quenching or “turn-off” was used to detect Cu (II [3]. In recent years, fluorescence “turn-on” emerges as a preferable tool. The developed fiber-optic sensor has two fiber leads and one probe head. One fiber lead includes 6 fibers for He-Ne laser excitation light delivery (e-fibers. Another fiber lead has one receiving fiber (r-fiber connected to an Ocean Optics QE65000 scientific grade spectrometer, which is interrogated by a computer via USB connection. The SpectroSuite software is used to observe and to record all spectra. The probe head combines all fibers together to form a coaxial structure with the r-fiber placed in the center. The key component in the proposed fluorescent sensing system is a probe prepared by binding a receptor containing a zwitterionic chromophore (M1, through noncovalent interactions, to the fluorescent polymer (P1 resulting in quenching its emission. The sensing mechanism

Optical radiation emissions from compact fluorescent lamps

International Nuclear Information System (INIS)

Khazova, M.; O'Hagan, J.B.

2008-01-01

There is a drive to energy efficiency to mitigate climate change. To meet this challenge, the UK Government has proposed phasing out incandescent lamps by the end of 2011 and replacing them with energy efficient fluorescent lighting, including compact fluorescent lamps (CFLs) with integrated ballasts. This paper presents a summary of an assessment conducted by the Health Protection Agency in March 2008 to evaluate the optical radiation emissions of CFLs currently available in the UK consumer market. The study concluded that the UV emissions from a significant percentage of the tested CFLs with single envelopes may result in foreseeable overexposure of the skin when these lamps are used in desk or task lighting applications. The optical output of all tested CFLs, in addition to high-frequency modulation, had a 100-Hz envelope with modulation in excess of 15%. This degree of modulation may be linked to a number of adverse effects. (authors)

Preparation and characterization of alginate based-fluorescent magnetic nanoparticles for fluorescence/magnetic resonance multimodal imaging applications

Science.gov (United States)

Kwon, Yong-Su; Choi, Kee-Bong; Lim, Hyungjun; Lee, Sunghwi; Lee, Jae-Jong

2018-06-01

Simple and versatile methodologies have been reported that customize the surface of superparamagnetic iron oxide (SPIO) nanoparticles and impart additional fluorescence capabilities to these contrast agents. Herein, we present the rational design, synthesis, characterization, and biological applications of a new magnetic-based fluorescent probe. The dual modality imaging protocol was developed by labeling fluorophore with alginate natural polymers that have excellent biocompatibility and biodegradability, and using gelification method to form nanocomposites containing SPIO. The formation of alginate-based fluorescent magnetic (AFM) nanoparticles was observed in spherical and elliptical forms with a diameter of less than 500 nm by a transmission electron microscope (TEM). The fluorescent wavelength band in the range of 560 nm was also confirmed in the UV–visible spectrophotometer. In this study, we demonstrate that the multi-tasking design of AFM nanoparticles provides an ideal platform for building balanced dual-image probes of magnetic resonance imaging and optical imaging.

Tomato seeds maturity detection system based on chlorophyll fluorescence

Science.gov (United States)

Li, Cuiling; Wang, Xiu; Meng, Zhijun

2016-10-01

Chlorophyll fluorescence intensity can be used as seed maturity and quality evaluation indicator. Chlorophyll fluorescence intensity of seed coats is tested to judge the level of chlorophyll content in seeds, and further to judge the maturity and quality of seeds. This research developed a detection system of tomato seeds maturity based on chlorophyll fluorescence spectrum technology, the system included an excitation light source unit, a fluorescent signal acquisition unit and a data processing unit. The excitation light source unit consisted of two high power LEDs, two radiators and two constant current power supplies, and it was designed to excite chlorophyll fluorescence of tomato seeds. The fluorescent signal acquisition unit was made up of a fluorescence spectrometer, an optical fiber, an optical fiber scaffolds and a narrowband filter. The data processing unit mainly included a computer. Tomato fruits of green ripe stage, discoloration stage, firm ripe stage and full ripe stage were harvested, and their seeds were collected directly. In this research, the developed tomato seeds maturity testing system was used to collect fluorescence spectrums of tomato seeds of different maturities. Principal component analysis (PCA) method was utilized to reduce the dimension of spectral data and extract principal components, and PCA was combined with linear discriminant analysis (LDA) to establish discriminant model of tomato seeds maturity, the discriminant accuracy was greater than 90%. Research results show that using chlorophyll fluorescence spectrum technology is feasible for seeds maturity detection, and the developed tomato seeds maturity testing system has high detection accuracy.

A disposable evanescent wave fiber optic sensor coated with a molecularly imprinted polymer as a selective fluorescence probe.

Science.gov (United States)

Ton, Xuan-Anh; Acha, Victor; Bonomi, Paolo; Tse Sum Bui, Bernadette; Haupt, Karsten

2015-02-15

We have developed a disposable evanescent wave fiber optic sensor by coating a molecularly imprinted polymer (MIP) containing a fluorescent signaling group on a 4-cm long polystyrene optical waveguide. The MIP is composed of a naphthalimide-based fluorescent monomer, which shows fluorescence enhancement upon binding with carboxyl-containing molecules. The herbicide 2,4-dichlorophenoxyacetic acid and the mycotoxin citrinin were used as model analytes. The coating of the MIP was either performed ex-situ, by dip-coating the fiber with MIP particles synthesized beforehand, or in-situ by evanescent-wave photopolymerization on the fiber. The sensing element was interrogated with a fiber-coupled spectrofluorimeter. The fiber optic sensor detects targets in the low nM range and exhibits specific and selective recognition over structural analogs and non-related carboxyl-containing molecules. This technology can be extended to other carboxyl-containing analytes, and to a broader spectrum of targets using different fluorescent monomers. Copyright © 2014 Elsevier B.V. All rights reserved.

Fluorescence based fibre optic pH sensor for the pH 10-13 range suitable for corrosion monitoring in concrete structures

OpenAIRE

Nguyen, T.H.; Venugopala, T.; Chen, S.; Sun, T.; Grattan, K. T. V.; Taylor, S.E.; Basheer, P.A.M.; Long, A.E.

2014-01-01

The design, development and evaluation of an optical fibre pH sensor for monitoring pH in the alkaline region are discussed in detail in this paper. The design of this specific pH sensor is based on the pH induced change in fluorescence intensity of a coumarin imidazole dye which is covalently attached to a polymer network and then fixed to the distal end of an optical fibre. The sensor provides a response over a pH range of 10.0 – 13.2 with an acceptable response rate of around 50 minutes, h...

Lifetime-based optical sensor for high-level pCO2 detection employing fluorescence resonance energy transfer

International Nuclear Information System (INIS)

Bueltzingsloewen, Christoph von; McEvoy, Aisling K.; McDonagh, Colette; MacCraith, Brian D.

2003-01-01

An optical sensor for the measurement of high levels of carbon dioxide in gas phase has been developed. It is based on fluorescence resonance energy transfer (FRET) between a long-lifetime ruthenium polypyridyl complex and the pH-active disazo dye Sudan III. The donor luminophore and the acceptor dye are both immobilised in a hydrophobic silica sol-gel/ethyl cellulose hybrid matrix material. Tetraoctylammonium hydroxide (TOA-OH) is used as an internal buffering system. Fluorescence lifetime is measured in the frequency domain, using low-cost phase modulation measurement technology. The use of Sudan III as an acceptor dye has enabled the sensor to have a dynamic range up to 100% carbon dioxide. The sensor displays 11.2 deg. phase shift between the limit of detection (LOD) of 0.06 and 100% CO 2 with a resolution of better than 2%. The encapsulation in the silica/polymer hybrid material has provided the sensor with good mechanical and chemical stability. The effect of molecular oxygen, humidity and temperature on the sensor performance was studied in detail

Design and synthesis of a fluorescent molecular imprinted polymer for use in an optical fibre-based cocaine sensor

Science.gov (United States)

Wren, Stephen P.; Piletsky, Sergey A.; Karim, Kal; Gascoine, Paul; Lacey, Richard; Sun, Tong; Grattan, Kenneth T. V.

2014-05-01

Previously, we have developed chemical sensors using fibre optic-based techniques for the detection of Cocaine, utilising molecularly imprinted polymers (MIPs) containing fluorescein moieties as the signalling groups. Here, we report the computational design of a fluorophore which was incorporated into a MIP for the generation of a novel sensor that offers improved sensitivity for Cocaine with a detection range of 1-100μM. High selectivity for Cocaine over a suite of known Cocaine interferants (25μM) was also demonstrated by measuring changes in the intensity of fluorescence signals received from the sensor.

Spatial discrimination against background with different optical systems for collection of fluorescence in laser-excited atomic fluorescence spectrometry with a graphite tube electrothermal atomizer.

Science.gov (United States)

Yuzefovsky, A I; Lonardo, R F; Michel, R G

1995-07-01

A single 90 degrees off-axis ellipsoidal mirror fragment was used in a dispersive detection system for electrothermal atomization laser-excited atomic fluorescence spectrometry. The performance of the new optical arrangement was compared with those of optical arrangements that employed a plane mirror in combination with biconvex or plano-convex lenses. All the optical arrangements collected fluorescence in a scheme called front surface illustration. BEAM-4, an optical ray tracing program, was used for calculations of spatial ray distributions and optical collection efficiency for the various optical configurations. Experimentally, the best collection efficiency was obtained by use of the ellipsoidal mirror, in qualitative agreement with simulations done by use of the BEAM-4 software. The best detection limit for cobalt with the new optical arrangement was 20 fg, which was a factor of 5 better than that obtained with conventional optical arrangements with otherwise the same instrumentation. The signal-to-background ratio and the fluorescence collection efficiency were also studied as a function of position of the optical components for the various optical arrangements. For both cobalt and phosphorus, the signal-to-background ratio with the new optical arrangement remained stable within 10-20% during +/- 8 mm shifts in the position of the detection system from the focal plane of the optics. Overall, the new optical arrangement offered high collection efficiency, excellent sensitivity, and facile optical alignment due to efficient spatial separation between the fluorescence signal and the background radiation. The advantages of the new optical arrangement were particularly important during measurements in the presence of high levels of blackbody radiation.

Multi-spectral and fluorescence diffuse optical tomography of breast cancer

Science.gov (United States)

Corlu, Alper

Multi-spectral and fluorescence diffuse optical tomography (DOT) techniques are explored and applied to image human breast cancer in vivo. Image reconstruction algorithms that utilize first and second order gradient information are described in detail. Breast DOT requires large computational memory and long run times. To this end, parallel computation techniques were developed appropriate to each reconstruction algorithm. A parallel plate DOT instrument developed for breast cancer imaging is described. The system relies heavily on continuous-wave (CW) transmission measurements and utilizes frequency domain (FD) measurements on the reemission side. However, traditional DOT image reconstruction methods based on CW measurements fail to separate tissue absorption and scattering uniquely. In this manuscript, multi-spectral DOT is shown to be capable of minimizing cross-talk and retrieving spectral parameters almost uniquely when the measurement wavelengths are optimized. A theoretical framework to select optimum wavelengths is provided, and tested with computer simulations. Results from phantom spectroscopy experiments and in vivo patient measurements support the notion that multi-spectral methods are superior to traditional DOT image reconstruction schemes. The same breast DOT instrument is improved and utilized to obtain the first in vivo images of human breast cancer based on fluorescence DOT (FDOT). To this end the fluorophore Indocyanine Green (ICG) is injected intravenously and fluorescence excitation and detection are accomplished in the soft-compression, parallel-plane, transmission geometry using laser sources at 786 nm and spectrally filtered CCD detection. Careful phantom and in vivo measurements are carried on to assure that the signals are due to ICG fluorescence, rather than tissue autofluorescence and excitation light leakage. An in vivo measurement protocol is designed to maximize the ICG contrast by acquiring full fluorescence tomographic scan during

A simple optical fiber device for quantitative fluorescence microscopy of single living cells

NARCIS (Netherlands)

van Graft, M.; van Graft, Marja; Oosterhuis, B.; Oosterhuis, Bernard; van der Werf, Kees; de Grooth, B.G.; Greve, Jan

1993-01-01

simple and relatively inexpensive system is described for obtaining quantitative fluorescence measurements on single living cells loaded with a fluorescent probe to study cell physiological processes. The light emitted from the fluorescent cells is captured by and transported through an optical

Non-invasive In Vivo Fluorescence Optical Imaging of Inflammatory MMP Activity Using an Activatable Fluorescent Imaging Agent.

Science.gov (United States)

Schwenck, Johannes; Maier, Florian C; Kneilling, Manfred; Wiehr, Stefan; Fuchs, Kerstin

2017-05-08

This paper describes a non-invasive method for imaging matrix metalloproteinases (MMP)-activity by an activatable fluorescent probe, via in vivo fluorescence optical imaging (OI), in two different mouse models of inflammation: a rheumatoid arthritis (RA) and a contact hypersensitivity reaction (CHR) model. Light with a wavelength in the near infrared (NIR) window (650 - 950 nm) allows a deeper tissue penetration and minimal signal absorption compared to wavelengths below 650 nm. The major advantages using fluorescence OI is that it is cheap, fast and easy to implement in different animal models. Activatable fluorescent probes are optically silent in their inactivated states, but become highly fluorescent when activated by a protease. Activated MMPs lead to tissue destruction and play an important role for disease progression in delayed-type hypersensitivity reactions (DTHRs) such as RA and CHR. Furthermore, MMPs are the key proteases for cartilage and bone degradation and are induced by macrophages, fibroblasts and chondrocytes in response to pro-inflammatory cytokines. Here we use a probe that is activated by the key MMPs like MMP-2, -3, -9 and -13 and describe an imaging protocol for near infrared fluorescence OI of MMP activity in RA and control mice 6 days after disease induction as well as in mice with acute (1x challenge) and chronic (5x challenge) CHR on the right ear compared to healthy ears.

Superior optical nonlinearity of an exceptional fluorescent stilbene dye

Energy Technology Data Exchange (ETDEWEB)

He, Tingchao [College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China); Division of Physics and Applied Physics, Centre for Disruptive Photonic Technologies (CDPT), School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore); Sreejith, Sivaramapanicker; Zhao, Yanli [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore); Gao, Yang; Grimsdale, Andrew C. [School of Materials Science and Engineering, Nanyang Technological University, Singapore, Singapore 639798 (Singapore); Lin, Xiaodong, E-mail: linxd@szu.edu.cn, E-mail: hdsun@ntu.edu.sg [College of Physics Science and Technology, Shenzhen University, Shenzhen 518060 (China); Sun, Handong, E-mail: linxd@szu.edu.cn, E-mail: hdsun@ntu.edu.sg [Division of Physics and Applied Physics, Centre for Disruptive Photonic Technologies (CDPT), School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore)

2015-03-16

Strong multiphoton absorption and harmonic generation in organic fluorescent chromophores are, respectively, significant in many fields of research. However, most of fluorescent chromophores fall short of the full potential due to the absence of the combination of such different nonlinear upconversion behaviors. Here, we demonstrate that an exceptional fluorescent stilbene dye could exhibit efficient two- and three-photon absorption under the excitation of femtosecond pulses in solution phase. Benefiting from its biocompatibility and strong excited state absorption behavior, in vitro two-photon bioimaging and superior optical limiting have been exploited, respectively. Simultaneously, the chromophore could generate efficient three-photon excited fluorescence and third-harmonic generation (THG) when dispersed into PMMA film, circumventing the limitations of classical fluorescent chromophores. Such chromophore may find application in the production of coherent light sources of higher photon energy. Moreover, the combination of three-photon excited fluorescence and THG can be used in tandem to provide complementary information in biomedical studies.

Optical diagnostic of breast cancer using Raman, polarimetric and fluorescence spectroscopy

Science.gov (United States)

Anwar, Shahzad; Firdous, Shamaraz; Rehman, Aziz-ul; Nawaz, Muhammed

2015-04-01

We presented the optical diagnostic of normal and cancerous human breast tissues using Raman, polarimetric and fluorescence spectroscopic techniques. Breast cancer is the second leading cause of cancer death among women worldwide. Optical diagnostics of cancer offered early intervention and the greatest chance of cure. Spectroscopic data were collected from freshly excised surgical specimens of normal tissues with Raman bands at 800, 1171 and 1530 cm-1 arising mainly by lipids, nucleic acids, proteins, carbohydrates and amino acids. For breast cancer, Raman bands are observed at 1070, 1211, 1495, 1583 and 1650 cm-1. Results demonstrate that the spectra of normal tissue are dominated by lipids and amino acids. Polarization decomposition of the Mueller matrix and confocal microscopic fluorescence provides detailed description of cancerous tissue and distinguishes between the normal and malignant one. Based on these findings, we successfully differentiate normal and malignant breast tissues at an early stage of disease. There is a need to develop a new tool for noninvasive, real-time diagnosis of tissue abnormalities and a test procedure for detecting breast cancer at an early stage.

An instrument for small-animal imaging using time-resolved diffuse and fluorescence optical methods

International Nuclear Information System (INIS)

Montcel, Bruno; Poulet, Patrick

2006-01-01

We describe time-resolved optical methods that use diffuse near-infrared photons to image the optical properties of tissues and their inner fluorescent probe distribution. The assembled scanner uses picosecond laser diodes at 4 wavelengths, an 8-anode photo-multiplier tube and time-correlated single photon counting. Optical absorption and reduced scattering images as well as fluorescence emission images are computed from temporal profiles of diffuse photons. This method should improve the spatial resolution and the quantification of fluorescence signals. We used the diffusion approximation of the radiation transport equation and the finite element method to solve the forward problem. The inverse problem is solved with an optimization algorithm such as ART or conjugate gradient. The scanner and its performances are presented, together with absorption, scattering and fluorescent images obtained with it

Development of a micro-X-ray fluorescence system based on polycapillary X-ray optics for non-destructive analysis of archaeological objects

Science.gov (United States)

Cheng, Lin; Ding, Xunliang; Liu, Zhiguo; Pan, Qiuli; Chu, Xuelian

2007-08-01

A new micro-X-ray fluorescence (micro-XRF) system based on rotating anode X-ray generator and polycapillary X-ray optics has been set up in XOL Lab, BNU, China, in order to be used for analysis of archaeological objects. The polycapillary X-ray optics used here can focus the primary X-ray beam down to tens of micrometers in diameter that allows for non-destructive and local analysis of sub-mm samples with minor/trace level sensitivity. The analytical characteristics and potential of this micro-XRF system in archaeological research are discussed. Some described uses of this instrument include studying Chinese ancient porcelain.

Development of a micro-X-ray fluorescence system based on polycapillary X-ray optics for non-destructive analysis of archaeological objects

Energy Technology Data Exchange (ETDEWEB)

Cheng Lin [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing Radiation Center, Beijing, 100875 (China)], E-mail: chenglin@bnu.edu.cn; Ding Xunliang; Liu Zhiguo; Pan Qiuli; Chu Xuelian [Key Laboratory of Beam Technology and Material Modification of Ministry of Education, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing Radiation Center, Beijing, 100875 (China)

2007-08-15

A new micro-X-ray fluorescence (micro-XRF) system based on rotating anode X-ray generator and polycapillary X-ray optics has been set up in XOL Lab, BNU, China, in order to be used for analysis of archaeological objects. The polycapillary X-ray optics used here can focus the primary X-ray beam down to tens of micrometers in diameter that allows for non-destructive and local analysis of sub-mm samples with minor/trace level sensitivity. The analytical characteristics and potential of this micro-XRF system in archaeological research are discussed. Some described uses of this instrument include studying Chinese ancient porcelain.

Ultrafast superresolution fluorescence imaging with spinning disk confocal microscope optics.

Science.gov (United States)

Hayashi, Shinichi; Okada, Yasushi

2015-05-01

Most current superresolution (SR) microscope techniques surpass the diffraction limit at the expense of temporal resolution, compromising their applications to live-cell imaging. Here we describe a new SR fluorescence microscope based on confocal microscope optics, which we name the spinning disk superresolution microscope (SDSRM). Theoretically, the SDSRM is equivalent to a structured illumination microscope (SIM) and achieves a spatial resolution of 120 nm, double that of the diffraction limit of wide-field fluorescence microscopy. However, the SDSRM is 10 times faster than a conventional SIM because SR signals are recovered by optical demodulation through the stripe pattern of the disk. Therefore a single SR image requires only a single averaged image through the rotating disk. On the basis of this theory, we modified a commercial spinning disk confocal microscope. The improved resolution around 120 nm was confirmed with biological samples. The rapid dynamics of micro-tubules, mitochondria, lysosomes, and endosomes were observed with temporal resolutions of 30-100 frames/s. Because our method requires only small optical modifications, it will enable an easy upgrade from an existing spinning disk confocal to a SR microscope for live-cell imaging. © 2015 Hayashi and Okada. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Fluorescence-based assay as a new screening tool for toxic chemicals

Science.gov (United States)

Moczko, Ewa; Mirkes, Evgeny M.; Cáceres, César; Gorban, Alexander N.; Piletsky, Sergey

2016-09-01

Our study involves development of fluorescent cell-based diagnostic assay as a new approach in high-throughput screening method. This highly sensitive optical assay operates similarly to e-noses and e-tongues which combine semi-specific sensors and multivariate data analysis for monitoring biochemical processes. The optical assay consists of a mixture of environmental-sensitive fluorescent dyes and human skin cells that generate fluorescence spectra patterns distinctive for particular physico-chemical and physiological conditions. Using chemometric techniques the optical signal is processed providing qualitative information about analytical characteristics of the samples. This integrated approach has been successfully applied (with sensitivity of 93% and specificity of 97%) in assessing whether particular chemical agents are irritating or not for human skin. It has several advantages compared with traditional biochemical or biological assays and can impact the new way of high-throughput screening and understanding cell activity. It also can provide reliable and reproducible method for assessing a risk of exposing people to different harmful substances, identification active compounds in toxicity screening and safety assessment of drugs, cosmetic or their specific ingredients.

Fluoromodule-based reporter/probes designed for in vivo fluorescence imaging

Science.gov (United States)

Zhang, Ming; Chakraborty, Subhasish K.; Sampath, Padma; Rojas, Juan J.; Hou, Weizhou; Saurabh, Saumya; Thorne, Steve H.; Bruchez, Marcel P.; Waggoner, Alan S.

2015-01-01

Optical imaging of whole, living animals has proven to be a powerful tool in multiple areas of preclinical research and has allowed noninvasive monitoring of immune responses, tumor and pathogen growth, and treatment responses in longitudinal studies. However, fluorescence-based studies in animals are challenging because tissue absorbs and autofluoresces strongly in the visible light spectrum. These optical properties drive development and use of fluorescent labels that absorb and emit at longer wavelengths. Here, we present a far-red absorbing fluoromodule–based reporter/probe system and show that this system can be used for imaging in living mice. The probe we developed is a fluorogenic dye called SC1 that is dark in solution but highly fluorescent when bound to its cognate reporter, Mars1. The reporter/probe complex, or fluoromodule, produced peak emission near 730 nm. Mars1 was able to bind a variety of structurally similar probes that differ in color and membrane permeability. We demonstrated that a tool kit of multiple probes can be used to label extracellular and intracellular reporter–tagged receptor pools with 2 colors. Imaging studies may benefit from this far-red excited reporter/probe system, which features tight coupling between probe fluorescence and reporter binding and offers the option of using an expandable family of fluorogenic probes with a single reporter gene. PMID:26348895

Smart phone based bacterial detection using bio functionalized fluorescent nanoparticles

International Nuclear Information System (INIS)

Rajendran, Vinoth Kumar; Bakthavathsalam, Padmavathy; Ali, Baquir Mohammed Jaffar

2014-01-01

We are describing immunochromatographic test strips with smart phone-based fluorescence readout. They are intended for use in the detection of the foodborne bacterial pathogens Salmonella spp. and Escherichia coli O157. Silica nanoparticles (SiNPs) were doped with FITC and Ru(bpy), conjugated to the respective antibodies, and then used in a conventional lateral flow immunoassay (LFIA). Fluorescence was recorded by inserting the nitrocellulose strip into a smart phone-based fluorimeter consisting of a light weight (40 g) optical module containing an LED light source, a fluorescence filter set and a lens attached to the integrated camera of the cell phone in order to acquire high-resolution fluorescence images. The images were analysed by exploiting the quick image processing application of the cell phone and enable the detection of pathogens within few minutes. This LFIA is capable of detecting pathogens in concentrations as low as 10 5 cfu mL −1 directly from test samples without pre-enrichment. The detection is one order of magnitude better compared to gold nanoparticle-based LFIAs under similar condition. The successful combination of fluorescent nanoparticle-based pathogen detection by LFIAs with a smart phone-based detection platform has resulted in a portable device with improved diagnosis features and having potential application in diagnostics and environmental monitoring. (author)

In Vivo Diffuse Optical Tomography and Fluorescence Molecular Tomography

Directory of Open Access Journals (Sweden)

Mingze Li

2010-01-01

Full Text Available Diffuse optical tomography (DOT and fluorescence molecular tomography (FMT are two attractive imaging techniques for in vivo physiological and psychological research. They have distinct advantages such as non-invasiveness, non-ionizing radiation, high sensitivity and longitudinal monitoring. This paper reviews the key components of DOT and FMT. Light propagation model, mathematical reconstruction algorithm, imaging instrumentation and medical applications are included. Future challenges and perspective on optical tomography are discussed.

Measurement of fluorescence emission spectrum of few strongly driven atoms using an optical nanofiber.

Science.gov (United States)

Das, Manoj; Shirasaki, A; Nayak, K P; Morinaga, M; Le Kien, Fam; Hakuta, K

2010-08-02

We show that the fluorescence emission spectrum of few atoms can be measured by using an optical nanofiber combined with the optical heterodyne and photon correlation spectroscopy. The observed fluorescence spectrum of the atoms near the nanofiber shows negligible effects of the atom-surface interaction and agrees well with the Mollow triplet spectrum of free-space atoms at high excitation intensity.

Fluorescent dyes with large Stokes shifts for super-resolution optical microscopy of biological objects: a review

International Nuclear Information System (INIS)

Sednev, Maksim V; Belov, Vladimir N; Hell, Stefan W

2015-01-01

The review deals with commercially available organic dyes possessing large Stokes shifts and their applications as fluorescent labels in optical microscopy based on stimulated emission depletion (STED). STED microscopy breaks Abbe’s diffraction barrier and provides optical resolution beyond the diffraction limit. STED microscopy is non-invasive and requires photostable fluorescent markers attached to biomolecules or other objects of interest. Up to now, in most biology-related STED experiments, bright and photoresistant dyes with small Stokes shifts of 20–40 nm were used. The rapid progress in STED microscopy showed that organic fluorophores possessing large Stokes shifts are indispensable in multi-color super-resolution techniques. The ultimate result of the imaging relies on the optimal combination of a dye, the bio-conjugation procedure and the performance of the optical microscope. Modern bioconjugation methods, basics of STED microscopy, as well as structures and spectral properties of the presently available fluorescent markers are reviewed and discussed. In particular, the spectral properties of the commercial dyes are tabulated and correlated with the available depletion wavelengths found in STED microscopes produced by LEICA Microsytems, Abberior Instruments and Picoquant GmbH. (topical review)

Correction of fluorescence for depth-specific optical and vascular properties using reflectance and differential path-length spectroscopy during PDT

Science.gov (United States)

van Zaane, F.; Middelburg, T. A.; de Bruijn, H. S.; van der Ploeg-van den Heuvel, A.; de Haas, E. R. M.; Sterenborg, H. J. C. M.; Neumann, H. A. M.; Robinson, D. J.

2009-06-01

Introduction: The rate of PpIX fluorescence photobleaching is routinely used as a dose metric for ALA-PDT. Diffuse reflection spectroscopy is often used to account for variations in tissue optical properties at the photosensitizer excitation and emission bands. It can be used to quantify changes in vascular parameters, such as blood volume fraction and saturation, and can aid understanding of tissue response to PDT. The volume and(/or) depth over which these signals are acquired are critical. The aim of this study is to use quantitative reflectance spectroscopy (DPS) to correct fluorescence for changes in tissue optical properties and monitor PDT. Materials & Methods: ALA was topically applied to hairless mice skin and the incubated spot was treated with PDT according to fractionated illumination schemes. DPS measurements of vascular parameters and optical properties were performed directly before and after illumination. Both the differential signal, delivery-and-collection-fiber signal and the collection fiber signal, which all probe different measurement volumes, are analyzed. Results & Conclusions: Analysis of DPS measurements shows that at the depth where most fluorescence originates, there is almost no blood present. During PDT vascular parameters at this depth stay constant. In more oxygenated layers of the tissue, the optical properties do change during PDT, suggesting that only a small part of PpIX fluorescence originates from the interesting depths where vascular response occurs. Correcting fluorescence emission spectra for optical changes at specific depths and not for the total of changes in a larger volume, as is usually done now, can improve PpIX photobleaching based treatment monitoring.

CMOS image sensor-based implantable glucose sensor using glucose-responsive fluorescent hydrogel.

Science.gov (United States)

Tokuda, Takashi; Takahashi, Masayuki; Uejima, Kazuhiro; Masuda, Keita; Kawamura, Toshikazu; Ohta, Yasumi; Motoyama, Mayumi; Noda, Toshihiko; Sasagawa, Kiyotaka; Okitsu, Teru; Takeuchi, Shoji; Ohta, Jun

2014-11-01

A CMOS image sensor-based implantable glucose sensor based on an optical-sensing scheme is proposed and experimentally verified. A glucose-responsive fluorescent hydrogel is used as the mediator in the measurement scheme. The wired implantable glucose sensor was realized by integrating a CMOS image sensor, hydrogel, UV light emitting diodes, and an optical filter on a flexible polyimide substrate. Feasibility of the glucose sensor was verified by both in vitro and in vivo experiments.

A PDMS-based cylindrical hybrid lens for enhanced fluorescence detection in microfluidic systems.

Science.gov (United States)

Lin, Bor-Shyh; Yang, Yu-Ching; Ho, Chong-Yi; Yang, Han-Yu; Wang, Hsiang-Yu

2014-02-13

Microfluidic systems based on fluorescence detection have been developed and applied for many biological and chemical applications. Because of the tiny amount of sample in the system; the induced fluorescence can be weak. Therefore, most microfluidic systems deploy multiple optical components or sophisticated equipment to enhance the efficiency of fluorescence detection. However, these strategies encounter common issues of complex manufacturing processes and high costs. In this study; a miniature, cylindrical and hybrid lens made of polydimethylsiloxane (PDMS) to improve the fluorescence detection in microfluidic systems is proposed. The hybrid lens integrates a laser focusing lens and a fluorescence collecting lens to achieve dual functions and simplify optical setup. Moreover, PDMS has advantages of low-cost and straightforward fabrication compared with conventional optical components. The performance of the proposed lens is first examined with two fluorescent dyes and the results show that the lens provides satisfactory enhancement for fluorescence detection of Rhodamine 6G and Nile Red. The overall increments in collected fluorescence signal and detection sensitivity are more than 220% of those without lens, and the detection limits of Rhodamine 6G and Nile red are lowered to 0.01 μg/mL and 0.05 μg/mL, respectively. The hybrid lens is further applied to the detection of Nile red-labeled Chlorella vulgaris cells and it increases both signal intensity and detection sensitivity by more than 520%. The proposed hybrid lens also dramatically reduces the variation in detected signal caused by the deviation in incident angle of excitation light.

Biomedical and sensing applications of a multi-mode biodegradable phosphate-based optical fiber

Science.gov (United States)

Podrazky, Ondřej; Peterka, Pavel; Vytykáčová, SoÅa.; Proboštová, Jana; Kuneš, Martin; Lyutakov, Oleksiy; Ceci-Ginistrelli, Edoardo; Pugliese, Diego; Boetti, Nadia G.; Janner, Davide; Milanese, Daniel

2018-02-01

We report on the employment of a biodegradable phosphate-based optical fiber as a pH sensing probe in physiological environment. The phosphate-based optical fiber preform was fabricated by the rod-in-tube technique. The fiber biodegradability was first tested in-vitro and then its biodegradability and toxicity were tested in-vivo. Optical probes for pH sensing were prepared by the immobilization of a fluorescent dye on the fiber tip by a sol-gel method. The fluorescence response of the pH-sensor was measured as a ratio of the emission intensities at the excitation wavelengths of 405 and 450 nm.

Time reversal optical tomography locates fluorescent targets in a turbid medium

Science.gov (United States)

Wu, Binlin; Cai, W.; Gayen, S. K.

2013-03-01

A fluorescence optical tomography approach that extends time reversal optical tomography (TROT) to locate fluorescent targets embedded in a turbid medium is introduced. It uses a multi-source illumination and multi-detector signal acquisition scheme, along with TR matrix formalism, and multiple signal classification (MUSIC) to construct pseudo-image of the targets. The samples consisted of a single or two small tubes filled with water solution of Indocyanine Green (ICG) dye as targets embedded in a 250 mm × 250 mm × 60 mm rectangular cell filled with Intralipid-20% suspension as the scattering medium. The ICG concentration was 1μM, and the Intralipid-20% concentration was adjusted to provide ~ 1-mm transport length for both excitation wavelength of 790 nm and fluorescence wavelength around 825 nm. The data matrix was constructed using the diffusely transmitted fluorescence signals for all scan positions, and the TR matrix was constructed by multiplying data matrix with its transpose. A pseudo spectrum was calculated using the signal subspace of the TR matrix. Tomographic images were generated using the pseudo spectrum. The peaks in the pseudo images provided locations of the target(s) with sub-millimeter accuracy. Concurrent transmission TROT measurements corroborated fluorescence-TROT findings. The results demonstrate that TROT is a fast approach that can be used to obtain accurate three-dimensional position information of fluorescence targets embedded deep inside a highly scattering medium, such as, a contrast-enhanced tumor in a human breast.

Quantification of tumor fluorescence during intraoperative optical cancer imaging.

Science.gov (United States)

Judy, Ryan P; Keating, Jane J; DeJesus, Elizabeth M; Jiang, Jack X; Okusanya, Olugbenga T; Nie, Shuming; Holt, David E; Arlauckas, Sean P; Low, Phillip S; Delikatny, E James; Singhal, Sunil

2015-11-13

Intraoperative optical cancer imaging is an emerging technology in which surgeons employ fluorophores to visualize tumors, identify tumor-positive margins and lymph nodes containing metastases. This study compares instrumentation to measure tumor fluorescence. Three imaging systems (Spectropen, Glomax, Flocam) measured and quantified fluorescent signal-to-background ratios (SBR) in vitro, murine xenografts, tissue phantoms and clinically. Evaluation criteria included the detection of small changes in fluorescence, sensitivity of signal detection at increasing depths and practicality of use. In vitro, spectroscopy was superior in detecting incremental differences in fluorescence than luminescence and digital imaging (Ln[SBR] = 6.8 ± 0.6, 2.4 ± 0.3, 2.6 ± 0.1, p = 0.0001). In fluorescent tumor cells, digital imaging measured higher SBRs than luminescence (6.1 ± 0.2 vs. 4.3 ± 0.4, p = 0.001). Spectroscopy was more sensitive than luminometry and digital imaging in identifying murine tumor fluorescence (SBR = 41.7 ± 11.5, 5.1 ± 1.8, 4.1 ± 0.9, p = 0.0001), and more sensitive than digital imaging at detecting fluorescence at increasing depths (SBR = 7.0 ± 3.4 vs. 2.4 ± 0.5, p = 0.03). Lastly, digital imaging was the most practical and least time-consuming. All methods detected incremental differences in fluorescence. Spectroscopy was the most sensitive for small changes in fluorescence. Digital imaging was the most practical considering its wide field of view, background noise filtering capability, and sensitivity to increasing depth.

Poly(diacetylene) Monolayers Studied with a Fluorescence Scanning Near-Field Optical Microscope

NARCIS (Netherlands)

Moers, Marco H.P.; Moers, M.H.P.; Gaub, Hermann E.; van Hulst, N.F.

1994-01-01

A novel and powerful method to study the optical properties of thin lipid films which a resolution superior to confocal microscopy is presented. With a scanning near-field optical microscope, fluorescence images of a Langmuir-Blodgett film of diethylene glycol diamine pentacosadiynoic amide are

A Starting Point for Fluorescence-Based Single-Molecule Measurements in Biomolecular Research

Directory of Open Access Journals (Sweden)

Alexander Gust

2014-09-01

Full Text Available Single-molecule fluorescence techniques are ideally suited to provide information about the structure-function-dynamics relationship of a biomolecule as static and dynamic heterogeneity can be easily detected. However, what type of single-molecule fluorescence technique is suited for which kind of biological question and what are the obstacles on the way to a successful single-molecule microscopy experiment? In this review, we provide practical insights into fluorescence-based single-molecule experiments aiming for scientists who wish to take their experiments to the single-molecule level. We especially focus on fluorescence resonance energy transfer (FRET experiments as these are a widely employed tool for the investigation of biomolecular mechanisms. We will guide the reader through the most critical steps that determine the success and quality of diffusion-based confocal and immobilization-based total internal reflection fluorescence microscopy. We discuss the specific chemical and photophysical requirements that make fluorescent dyes suitable for single-molecule fluorescence experiments. Most importantly, we review recently emerged photoprotection systems as well as passivation and immobilization strategies that enable the observation of fluorescently labeled molecules under biocompatible conditions. Moreover, we discuss how the optical single-molecule toolkit has been extended in recent years to capture the physiological complexity of a cell making it even more relevant for biological research.

Fully time-resolved near-field scanning optical microscopy fluorescence imaging

International Nuclear Information System (INIS)

Kwak, Eun-Soo; Vanden Bout, David A.

2003-01-01

Time-correlated single photon counting has been coupled with near-field scanning optical microscopy (NSOM) to record complete fluorescence lifetime decays at each pixel in an NSOM image. The resulting three-dimensional data sets can be binned in the time dimension to create images of photons at particular time delays or images of the fluorescence lifetime. Alternatively, regions of interest identified in the topography and fluorescence images can be used to bin the data in the spatial dimensions resulting in high signal to noise fluorescence decays of particular regions of the sample. The technique has been demonstrated on films of poly(vinylalcohol), doped with the fluorescent dye, cascade blue (CB). The CB segregates into small circular regions of high concentration within the films during the drying process. The lifetime imaging shows that the spots have slightly faster excited state decays due to quenching of the luminescence as a result of the higher concentration. The technique is also used to image the fluorescence lifetime of an annealed film of poly(dihexylfluorene). The samples show high contrast in the total intensity fluorescence image, but the lifetime image reveals the sample to be extremely uniform

Observation of self-assembled fluorescent beads by scanning near-field optical microscopy and atomic force microscopy

International Nuclear Information System (INIS)

Oh, Y.J.; Jo, W.; Kim, Min-Gon; Kyu Park, Hyun; Hyun Chung, Bong

2006-01-01

Optical response and topography of fluorescent latex beads both on flat self-assembled monolayer and on a micron-patterned surface with poly(dimethylsiloxane) are studied. Scanning near-field optical microscopy and atomic force microscopy were utilized together for detecting fluorescence and imaging topography of the patterned latex beads, respectively. As a result, the micro-patterned latex beads where a specific chemical binding occurred show a strong signal, whereas no signals are observed in the case of nonspecific binding. With fluorescein isothiocyanate (FITC), it is convenient to measure fluorescence signal from the patterned beads allowing us to monitor the small balls of fluorescent latex

Fiber optic-based biosensor

Science.gov (United States)

Ligler, Frances S.

1991-01-01

The NRL fiber optic biosensor is a device which measures the formation of a fluorescent complex at the surface of an optical fiber. Antibodies and DNA binding proteins provide the mechanism for recognizing an analyze and immobilizing a fluorescent complex on the fiber surface. The fiber optic biosensor is fast, sensitive, and permits analysis of hazardous materials remote from the instrumentation. The fiber optic biosensor is described in terms of the device configuration, chemistry for protein immobilization, and assay development. A lab version is being used for assay development and performance characterization while a portable device is under development. Antibodies coated on the fiber are stable for up to two years of storage prior to use. The fiber optic biosensor was used to measure concentration of toxins in the parts per billion (ng/ml) range in under a minute. Immunoassays for small molecules and whole bacteria are under development. Assays using DNA probes as the detection element can also be used with the fiber optic sensor, which is currently being developed to detect biological warfare agents, explosives, pathogens, and toxic materials which pollute the environment.

Tools for the quantitative analysis of sedimentation boundaries detected by fluorescence optical analytical ultracentrifugation.

Directory of Open Access Journals (Sweden)

Huaying Zhao

Full Text Available Fluorescence optical detection in sedimentation velocity analytical ultracentrifugation allows the study of macromolecules at nanomolar concentrations and below. This has significant promise, for example, for the study of systems of high-affinity protein interactions. Here we describe adaptations of the direct boundary modeling analysis approach implemented in the software SEDFIT that were developed to accommodate unique characteristics of the confocal fluorescence detection system. These include spatial gradients of signal intensity due to scanner movements out of the plane of rotation, temporal intensity drifts due to instability of the laser and fluorophores, and masking of the finite excitation and detection cone by the sample holder. In an extensive series of experiments with enhanced green fluorescent protein ranging from low nanomolar to low micromolar concentrations, we show that the experimental data provide sufficient information to determine the parameters required for first-order approximation of the impact of these effects on the recorded data. Systematic deviations of fluorescence optical sedimentation velocity data analyzed using conventional sedimentation models developed for absorbance and interference optics are largely removed after these adaptations, resulting in excellent fits that highlight the high precision of fluorescence sedimentation velocity data, thus allowing a more detailed quantitative interpretation of the signal boundaries that is otherwise not possible for this system.

Evaluation of dental enamel caries assessment using Quantitative Light Induced Fluorescence and Optical Coherence Tomography.

Science.gov (United States)

Maia, Ana Marly Araújo; de Freitas, Anderson Zanardi; de L Campello, Sergio; Gomes, Anderson Stevens Leônidas; Karlsson, Lena

2016-06-01

An in vitro study of morphological alterations between sound dental structure and artificially induced white spot lesions in human teeth, was performed through the loss of fluorescence by Quantitative Light-Induced Fluorescence (QLF) and the alterations of the light attenuation coefficient by Optical Coherence Tomography (OCT). To analyze the OCT images using a commercially available system, a special algorithm was applied, whereas the QLF images were analyzed using the software available in the commercial system employed. When analyzing the sound region against white spot lesions region by QLF, a reduction in the fluorescence intensity was observed, whilst an increase of light attenuation by the OCT system occurred. Comparison of the percentage of alteration between optical properties of sound and artificial enamel caries regions showed that OCT processed images through the attenuation of light enhanced the tooth optical alterations more than fluorescence detected by QLF System. QLF versus OCT imaging of enamel caries: a photonics assessment. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mobile Phone Ratiometric Imaging Enables Highly Sensitive Fluorescence Lateral Flow Immunoassays without External Optical Filters.

Science.gov (United States)

Shah, Kamal G; Singh, Vidhi; Kauffman, Peter C; Abe, Koji; Yager, Paul

2018-05-14

Paper-based diagnostic tests based on the lateral flow immunoassay concept promise low-cost, point-of-care detection of infectious diseases, but such assays suffer from poor limits of detection. One factor that contributes to poor analytical performance is a reliance on low-contrast chromophoric optical labels such as gold nanoparticles. Previous attempts to improve the sensitivity of paper-based diagnostics include replacing chromophoric labels with enzymes, fluorophores, or phosphors at the expense of increased fluidic complexity or the need for device readers with costly optoelectronics. Several groups, including our own, have proposed mobile phones as suitable point-of-care readers due to their low cost, ease of use, and ubiquity. However, extant mobile phone fluorescence readers require costly optical filters and were typically validated with only one camera sensor module, which is inappropriate for potential point-of-care use. In response, we propose to couple low-cost ultraviolet light-emitting diodes with long Stokes-shift quantum dots to enable ratiometric mobile phone fluorescence measurements without optical filters. Ratiometric imaging with unmodified smartphone cameras improves the contrast and attenuates the impact of excitation intensity variability by 15×. Practical application was shown with a lateral flow immunoassay for influenza A with nucleoproteins spiked into simulated nasal matrix. Limits of detection of 1.5 and 2.6 fmol were attained on two mobile phones, which are comparable to a gel imager (1.9 fmol), 10× better than imaging gold nanoparticles on a scanner (18 fmol), and >2 orders of magnitude better than gold nanoparticle-labeled assays imaged with mobile phones. Use of the proposed filter-free mobile phone imaging scheme is a first step toward enabling a new generation of highly sensitive, point-of-care fluorescence assays.

Dynamic Assessment of the Endothelialization of Tissue-Engineered Blood Vessels Using an Optical Coherence Tomography Catheter-Based Fluorescence Imaging System.

Science.gov (United States)

Gurjarpadhye, Abhijit Achyut; DeWitt, Matthew R; Xu, Yong; Wang, Ge; Rylander, Marissa Nichole; Rylander, Christopher G

2015-07-01

Lumen endothelialization of bioengineered vascular scaffolds is essential to maintain small-diameter graft patency and prevent thrombosis postimplantation. Unfortunately, nondestructive imaging methods to visualize this dynamic process are lacking, thus slowing development and clinical translation of these potential tissue-engineering approaches. To meet this need, a fluorescence imaging system utilizing a commercial optical coherence tomography (OCT) catheter was designed to visualize graft endothelialization. C7 DragonFly™ intravascular OCT catheter was used as a channel for delivery and collection of excitation and emission spectra. Poly-dl-lactide (PDLLA) electrospun scaffolds were seeded with endothelial cells (ECs). Seeded cells were exposed to Calcein AM before imaging, causing the living cells to emit green fluorescence in response to blue laser. By positioning the catheter tip precisely over a specimen using high-fidelity electromechanical components, small regions of the specimen were excited selectively. The resulting fluorescence intensities were mapped on a two-dimensional digital grid to generate spatial distribution of fluorophores at single-cell-level resolution. Fluorescence imaging of endothelialization on glass and PDLLA scaffolds was performed using the OCT catheter-based imaging system as well as with a commercial fluorescence microscope. Cell coverage area was calculated for both image sets for quantitative comparison of imaging techniques. Tubular PDLLA scaffolds were maintained in a bioreactor on seeding with ECs, and endothelialization was monitored over 5 days using the OCT catheter-based imaging system. No significant difference was observed in images obtained using our imaging system to those acquired with the fluorescence microscope. Cell area coverage calculated using the images yielded similar values. Nondestructive imaging of endothelialization on tubular scaffolds showed cell proliferation with cell coverage area increasing from

Fluorescence monitoring of capillary electrophoresis separation of biomolecules with monolithically integrated optical waveguides

NARCIS (Netherlands)

Dongre, C.; Dekker, R.; Hoekstra, Hugo; Martinez-Vazquez, R.; Osellame, R.; Ramponi, R.; Cerullo, G.; van Weeghel, R.; Besselink, G.A.J.; van den Vlekkert, H.H.; Pollnau, Markus

2009-01-01

Monolithic integration of optical waveguides in a commercial lab-on-a-chip by femtosecond-laser material processing enables arbitrary 3D geometries of optical sensing structures in combination with fluidic microchannels. Integrated fluorescence monitoring of molecular separation, as applicable in

Catheter-based time-gated near-infrared fluorescence/OCT imaging system

Science.gov (United States)

Lu, Yuankang; Abran, Maxime; Cloutier, Guy; Lesage, Frédéric

2018-02-01

We developed a new dual-modality intravascular imaging system based on fast time-gated fluorescence intensity imaging and spectral domain optical coherence tomography (SD-OCT) for the purpose of interventional detection of atherosclerosis. A pulsed supercontinuum laser was used for fluorescence and OCT imaging. A double-clad fiber (DCF)- based side-firing catheter was designed and fabricated to have a 23 μm spot size at a 2.2 mm working distance for OCT imaging. Its single-mode core is used for OCT, while its inner cladding transports fluorescence excitation light and collects fluorescent photons. The combination of OCT and fluorescence imaging was achieved by using a DCF coupler. For fluorescence detection, we used a time-gated technique with a novel single-photon avalanche diode (SPAD) working in an ultra-fast gating mode. A custom-made delay chip was integrated in the system to adjust the delay between the excitation laser pulse and the SPAD gate-ON window. This technique allowed to detect fluorescent photons of interest while rejecting most of the background photons, thus leading to a significantly improved signal to noise ratio (SNR). Experiments were carried out in turbid media mimicking tissue with an indocyanine green (ICG) inclusion (1 mM and 100 μM) to compare the time-gated technique and the conventional continuous detection technique. The gating technique increased twofold depth sensitivity, and tenfold SNR at large distances. The dual-modality imaging capacity of our system was also validated with a silicone-based tissue-mimicking phantom.

A set-up of micro-X-ray fluorescence system based on polycapillary X-ray optics and applications for archaeology

International Nuclear Information System (INIS)

Cheng Lin; Pan Qiuli; Ding Xunliang; Liu Zhiguo

2008-01-01

The paper concerns in the structures, performances and characteristics and applications for archaeology of a new micro-X-ray fluorescence system based on rotating anode X-ray generator and polycapillary X-ray optics. The polycapillary X-ray optics used here can focus the primary X-ray beam down to some tens of micrometers in diameters that allows for non-destructive and local analysis of sub-mm samples with minor/ trace level sensitivity. In order to prove the potentials of this instrument used in archaeology, a piece of Chinese ancient blue and white porcelain produced in Ming Dynasty was analyzed. The results show that intensities of Mn-Kα, Co-Kα are variable in agree with the thick of blue glaze. The correlation analysis indicates the Mn and Co have the best correlations. So, the concentrations or ratios of Mn and Co are crucial to determine the provenance and identify from a fake one of Chinese ancient blue and white porcelain. (authors)

Optical absorption and fluorescence studies of praseodymium ion in chloroborophosphate glasses

International Nuclear Information System (INIS)

Sharma, Y.K.; Tandon, S.P.

1998-01-01

Full text: The interest in optical absorption and fluorescence studies of rare earth ions in glassy materials is increasing continuously in connection with laser research and related application. The absorption and fluorescence spectra of praseodymium ion in chloroborophosphate glasses have been recorded at room temperature. The chloroborophosphate glass specimens having composition in mob.% Na 2 0 (26.08), B 2 0 3 (14.57), P 2 0 5 (44.85), ZnCl 2 (14.50), Pr 6 0 11 (R) [R= 0.0,0.1 and 0.2 moi.%] have been prepared by melt quenching technique. The spectra consists of seven absorption bands and three fluorescence bands. The observed optical spectra are discussed in terms of energy state and the intensity of the transitions. The various energy interaction parameters like Slater-Condon, Lande', Racah and bonding parameters have been computed. Judd-Ofeit intensity parameters and laser parameters have also been computed. These results shows that praseodymium doped chloroborophosphate glass specimen can be considered as good hosts for laser applications

The temporal evolution process from fluorescence bleaching to clean Raman spectra of single solid particles optically trapped in air

Science.gov (United States)

Gong, Zhiyong; Pan, Yong-Le; Videen, Gorden; Wang, Chuji

2017-12-01

We observe the entire temporal evolution process of fluorescence and Raman spectra of single solid particles optically trapped in air. The spectra initially contain strong fluorescence with weak Raman peaks, then the fluorescence was bleached within seconds, and finally only the clean Raman peaks remain. We construct an optical trap using two counter-propagating hollow beams, which is able to stably trap both absorbing and non-absorbing particles in air, for observing such temporal processes. This technique offers a new method to study dynamic changes in the fluorescence and Raman spectra from a single optically trapped particle in air.

Enhancing early bladder cancer detection with fluorescence-guided endoscopic optical coherence tomography

Science.gov (United States)

Pan, Y. T.; Xie, T. Q.; Du, C. W.; Bastacky, S.; Meyers, S.; Zeidel, M. L.

2003-12-01

We report an experimental study of the possibility of enhancing early bladder cancer diagnosis with fluorescence-image-guided endoscopic optical coherence tomography (OCT). After the intravesical instillation of a 10% solution of 5-aminolevulinic acid, simultaneous fluorescence imaging (excitation of 380-420 nm, emission of 620-700 nm) and OCT are performed on rat bladders to identify the photochemical and morphological changes associated with uroepithelial tumorigenesis. The preliminary results of our ex vivo study reveal that both fluorescence and OCT can identify early uroepithelial cancers, and OCT can detect precancerous lesions (e.g., hyperplasia) that fluorescence may miss. This suggests that a cystoscope combining 5-aminolevulinic acid fluorescence and OCT imaging has the potential to enhance the efficiency and sensitivity of early bladder cancer diagnosis.

Fast and sensitive medical diagnostic protocol based on integrating circular current lines for magnetic washing and optical detection of fluorescent magnetic nanobeads

Directory of Open Access Journals (Sweden)

Jaiyam Sharma

2016-07-01

Full Text Available Magnetic nanoparticles (MNPs are increasingly being used as ‘magnetic labels’ in medical diagnostics. Practical applications of MNPs necessitate reducing their non-specific interactions with sensor surfaces that result in noise in measurements. Here we describe the design and implementation of a sensing platform that incorporates circular shaped current lines that reduce non-specific binding by enabling the “magnetic washing” of loosely attached MNPs attached to the senor surface. Generating magnetic fields by passing electrical currents through the circular shaped current lines enabled the capture and collection of fluorescent MNPs that was more efficient and effective than straight current lines reported to-date. The use of fluorescent MNPs allows their optical detection rather than with widely used magnetoresistive sensors. As a result our approach is not affected by magnetic noise due to the flow of currents. Our design is expected to improve the speed, accuracy, and sensitivity of MNPs based medical diagnostics. Keywords: Biosensors, Magnetic beads, Fluorescent magnetic nanoparticles, Lab on chip, Point of care testing

Detection of volatile and soluble general anesthetics using a fluorescence-based fiber optic sensor: recent progress in chemical sensitivity and noise sources

Science.gov (United States)

Yager, Paul; Abrams, Susan B.

1992-04-01

A fiber optic sensor for general anesthetics based on the phase transition of immobilized phospholipid vesicles is under development. Current work centers on evaluating the sensor response to different anesthetics and instrumentation design. The fluorescence of laurdan- doped liposomes is found to respond linearly to the infusible anesthetics thiopental sodium and Propofol. Preliminary experiments have been performed to determine sources of noise in the optical and electronic components of the sensor as it is now configured. One potential noise source is the liposome sample at the fiber tip; photobleaching and thermal fluctuations due to heating by the illuminating 360 nm radiation can affect measurement of the anesthetic level. Heating of the sample is a factor at high illumination levels, but photobleaching, which reduces the signal intensity, does not alter the intensity ratio upon which the anesthetic concentration measurement is based. Optical microscopy of fiber tips embedded in liposomes allows direct observation of the light intensity near the tip of the fiber despite the extreme turbidity of the suspension. Light intensity drops to less than 10% of its maximum intensity at the fiber tip within 300 micrometers . Further use of this technique should allow monitoring the effects of photobleaching on the spatial distribution of the liposomes responsible for the measured optical signal.

Fluorescent nanocellulosic hydrogels based on graphene quantum dots for sensing laccase

International Nuclear Information System (INIS)

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

2017-01-01

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

Optical fluorescence spectroscopy to detect hepatic necrosis after normothermic ischemia: animal model

Science.gov (United States)

Romano, Renan A.; Vollet-Filho, Jose D.; Pratavieira, Sebastião.; Fernandez, Jorge L.; Kurachi, Cristina; Bagnato, Vanderlei S.; Castro-e-Silva, Orlando; Sankarankutty, Ajith K.

2015-06-01

Liver transplantation is a well-established treatment for liver failure. However, the success of the transplantation procedure depends on liver graft conditions. The tissue function evaluation during the several transplantation stages is relevant, in particular during the organ harvesting, when a decision is made concerning the viability of the graft. Optical fluorescence spectroscopy is a good option because it is a noninvasive and fast technique. A partial normothermic hepatic ischemia was performed in rat livers, with a vascular occlusion of both median and left lateral lobes, allowing circulation only for the right lateral lobe and the caudate lobe. Fluorescence spectra under excitation at 532 nm (doubled frequency Nd:YAG laser) were collected using a portable spectrometer (USB2000, Ocean Optics, USA). The fluorescence emission was collected before vascular occlusion, after ischemia, and 24 hours after reperfusion. A morphometric histology analysis was performed as the gold standard evaluation - liver samples were analyzed, and the percentage of necrotic tissue was obtained. The results showed that changes in the fluorescence emission after ischemia can be correlated with the amount of necrosis evaluated by a morphometric analysis, the Pearson correlation coefficient of the generated model was 0.90 and the root mean square error was around 20%. In this context, the laser-induced fluorescence spectroscopy technique after normothermic ischemia showed to be a fast and efficient method to differentiate ischemic injury from viable tissues.

Highly fluorescent silver nanoclusters in alumina-silica composite optical fiber

Energy Technology Data Exchange (ETDEWEB)

Halder, A.; Chattopadhyay, R.; Majumder, S.; Paul, M. C.; Das, S.; Bhadra, S. K., E-mail: skbhadra@cgcri.res.in [Fiber Optics and Photonics Division, CSIR-Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Road, Kolkata 700032 (India); Bysakh, S.; Unnikrishnan, M. [Material Characterization Division, CSIR-Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Road, Kolkata 700032 (India)

2015-01-05

An efficient visible fluorescent optical fiber embedded with silver nanoclusters (Ag-NCs) having size ∼1 nm, uniformly distributed in alumina-silica composite core glass, is reported. Fibers are fabricated in a repetitive controlled way through modified chemical vapour deposition process associated with solution doping technique. Fibers are drawn from the transparent preforms by conventional fiber drawing process. Structural characteristics of the doped fibers are studied using transmission electron microscopy and electron probe micro analysis. The oxidation state of Ag within Ag-NCs is investigated by X-ray photo electron spectroscopy. The observed significant fluorescence of the metal clusters in fabricated fibers is correlated with electronic model. The experimentally observed size dependent absorption of the metal clusters in fabricated fibers is explained with the help of reported results calculated by ab-initio density functional theory. These optical fibers may open up an opportunity of realizing tunable wavelength fiber laser without the help of rare earth elements.

Optical properties of flexible fluorescent films prepared by screen printing technology

Directory of Open Access Journals (Sweden)

Yan Chen

2018-05-01

Full Text Available In this work, we prepared a fluorescent film comprised phosphors and silicone on flexible polyethylene terephthalate (PET substrate using a screen printing technology. The effects of mesh number and weight ratio of phosphors to silicone on the optical properties of the flexible films were investigated. The results indicate that the emission intensity of the film increase as the mesh decreased from 400 to 200, but the film surface gradually becomes uneven. The fluorescent film with high emission intensity and smooth surface can be obtained when the weight ratio of phosphor to gel is 2:1, and mesh number is 300. The luminous efficiency of the fabricated LEDs combined the fluorescent films with 460 nm Ga(InN chip module can reach 75 lm/W. The investigation indicates that the approach can be applied in the remote fluorescent film conversion and decreases the requirements of the particle size and the dispersion state of fluorescent materials.

Optical properties of flexible fluorescent films prepared by screen printing technology

Science.gov (United States)

Chen, Yan; Ke, Taiyan; Chen, Shuijin; He, Xin; Zhang, Mei; Li, Dong; Deng, Jinfeng; Zeng, Qingguang

2018-05-01

In this work, we prepared a fluorescent film comprised phosphors and silicone on flexible polyethylene terephthalate (PET) substrate using a screen printing technology. The effects of mesh number and weight ratio of phosphors to silicone on the optical properties of the flexible films were investigated. The results indicate that the emission intensity of the film increase as the mesh decreased from 400 to 200, but the film surface gradually becomes uneven. The fluorescent film with high emission intensity and smooth surface can be obtained when the weight ratio of phosphor to gel is 2:1, and mesh number is 300. The luminous efficiency of the fabricated LEDs combined the fluorescent films with 460 nm Ga(In)N chip module can reach 75 lm/W. The investigation indicates that the approach can be applied in the remote fluorescent film conversion and decreases the requirements of the particle size and the dispersion state of fluorescent materials.

Design, manufacturing and alignment of a fluorescence imaging spectrometer based on refractive optics and a transmission grating

Science.gov (United States)

Lousberg, G. P.; Lemagne, F.; Gloesener, P.; Flebus, C.; Rougelot, S.; Coatantiec, C.; Harnisch, B.

2017-11-01

In the framework of the Fluorescence Explorer (FLEX) phase A/B1 study, an elegant breadboard (EBB) of an imaging spectrometer is designed, manufactured and aligned by AMOS, with Airbus Defence&Space as the prime Contractor of the study. The FLEX mission is one of the two candidates of the 8th Earth Explorer mission. The main constituting instrument of the FLEX mission is an imaging spectrometer observing vegetation fluorescence and reflectance with a high- and a low-resolution channels in the 500 nm -780 nm band. As part of the system feasibility study of the mission, a breadboard of the high-resolution channel of the instrument is designed and manufactured with a high representativeness of a future flight concept. The high-resolution channel is referred to as FIMAS (Fluorescence IMAging Spectrometer). The main purpose of the EBB is to demonstrate (1) the manufacturability of the instrument and (2) the compliance of the optical performances with respect to the science requirements (including spatial and spectral resolution and stray-light).

An image fiber based fluorescent probe with associated signal processing scheme for biomedical diagnostics

International Nuclear Information System (INIS)

Vaishakh, M; Murukeshan, V M; Seah, L K

2008-01-01

A dual-modality image fiber based fluorescent probe that can be used for depth sensitive imaging and suppression of fluorescent emissions with nanosecond lifetime difference is proposed and illustrated in this paper. The system can give high optical sectioning and employs an algorithm for obtaining phase sensitive images. The system can find main application in in vivo biomedical diagnostics for detecting biochemical changes for distinguishing malignant tissue from healthy tissue

Fiber optic medical and fluorescent sensors and applications; Proceedings of the Meeting, Los Angeles, CA, Jan. 23, 24, 1992

Energy Technology Data Exchange (ETDEWEB)

Hansmann, D.R.; Milanovich, F.P.; Vurek, G.G.; Walt, D.R. (3M Center, Saint Paul, MN (United States) Lawrence Livermore National Laboratory, Livermore, CA (United States) Abbott Laboratories, North Chicago, IL (United States) Tufts University, Medford, MA (United States))

1992-01-01

Papers are presented on such topics as the optical measurement of blood gases; waveguide ellipsometry biosensors; a novel fiber-optic radiation sensor for in vivo dosimetry; and a fiber-optic sensor for simultaneous oxygen saturation and blood pressure measurements. Fluorescent sensors are then considered with reference to sensor fabrication and design, and fluorescence sensing schemes, indicators, and reagents.

Improving your four-dimensional image: traveling through a decade of light-sheet-based fluorescence microscopy research.

Science.gov (United States)

Strobl, Frederic; Schmitz, Alexander; Stelzer, Ernst H K

2017-06-01

Light-sheet-based fluorescence microscopy features optical sectioning in the excitation process. This reduces phototoxicity and photobleaching by up to four orders of magnitude compared with that caused by confocal fluorescence microscopy, simplifies segmentation and quantification for three-dimensional cell biology, and supports the transition from on-demand to systematic data acquisition in developmental biology applications.

Fluorescence based molecular in vivo imaging

International Nuclear Information System (INIS)

Ebert, Bernd

2008-01-01

Molecular imaging represents a modern research area that allows the in vivo study of molecular biological process kinetics using appropriate probes and visualization methods. This methodology may be defined- apart from the contrast media injection - as non-abrasive. In order to reach an in vivo molecular process imaging as accurate as possible the effects of the used probes on the biological should not be too large. The contrast media as important part of the molecular imaging can significantly contribute to the understanding of molecular processes and to the development of tailored diagnostics and therapy. Since more than 15 years PTB is developing optic imaging systems that may be used for fluorescence based visualization of tissue phantoms, small animal models and the localization of tumors and their predecessors, and for the early recognition of inflammatory processes in clinical trials. Cellular changes occur during many diseases, thus the molecular imaging might be of importance for the early diagnosis of chronic inflammatory diseases. Fluorescent dyes can be used as unspecific or also as specific contrast media, which allow enhanced detection sensitivity

DMD-based LED-illumination super-resolution and optical sectioning microscopy.

Science.gov (United States)

Dan, Dan; Lei, Ming; Yao, Baoli; Wang, Wen; Winterhalder, Martin; Zumbusch, Andreas; Qi, Yujiao; Xia, Liang; Yan, Shaohui; Yang, Yanlong; Gao, Peng; Ye, Tong; Zhao, Wei

2013-01-01

Super-resolution three-dimensional (3D) optical microscopy has incomparable advantages over other high-resolution microscopic technologies, such as electron microscopy and atomic force microscopy, in the study of biological molecules, pathways and events in live cells and tissues. We present a novel approach of structured illumination microscopy (SIM) by using a digital micromirror device (DMD) for fringe projection and a low-coherence LED light for illumination. The lateral resolution of 90 nm and the optical sectioning depth of 120 μm were achieved. The maximum acquisition speed for 3D imaging in the optical sectioning mode was 1.6×10(7) pixels/second, which was mainly limited by the sensitivity and speed of the CCD camera. In contrast to other SIM techniques, the DMD-based LED-illumination SIM is cost-effective, ease of multi-wavelength switchable and speckle-noise-free. The 2D super-resolution and 3D optical sectioning modalities can be easily switched and applied to either fluorescent or non-fluorescent specimens.

Biomolecule-to-fluorescent-color encoder: modulation of fluorescence emission via DNA structural changes

Science.gov (United States)

Nishimura, Takahiro; Ogura, Yusuke; Yamada, Kenji; Ohno, Yuko; Tanida, Jun

2014-01-01

A biomolecule-to-fluorescent-color (B/F) encoder for optical readout of biomolecular information is proposed. In the B/F encoder, a set of fluorescence wavelengths and their intensity levels are used for coding of a biomolecular signal. A hybridization chain reaction of hairpin DNAs labeled with fluorescent reporters was performed to generate the fluorescence color codes. The fluorescence is modulated via fluorescence resonance energy transfer, which is controlled by DNA structural changes. The results demonstrate that fluorescent color codes can be configured based on two wavelengths and five intensities using the B/F encoder, and the assigned codes can be retrieved via fluorescence measurements. PMID:25071950

Fluorescence in situ hybridization on human metaphase chromosomes detected by near-field scanning optical microscopy

NARCIS (Netherlands)

Moers, M.H.P.; Moers, M.H.P.; Kalle, W.H.J.; Kalle, W.H.J.; Ruiter, A.G.T.; Wiegant, J.C.A.G.; Raap, A.K.; Greve, Jan; de Grooth, B.G.; van Hulst, N.F.

1996-01-01

Fluorescence in situ hybridization o­n human metaphase chromosomes is detected by near-field scanning optical microscopy. This combination of cytochemical and scanning probe techniques enables the localization and identification of several fluorescently labelled genomic DNA fragments o­n a single

Fluorescent nanoscale detection of biotin-streptavidin interaction using near-field scanning optical microscopy

International Nuclear Information System (INIS)

Park, Hyun Kyu; Chung, Bong Hyun; Gokarna, Anisha; Hulme, John P; Park, Hyun Gyu

2008-01-01

We describe a nanoscale strategy for detecting biotin-streptavidin binding using near-field scanning optical microscopy (NSOM) that exploits the fluorescence properties of single polydiacetylene (PDA) liposomes. NSOM is more useful to observe nanomaterials having optical properties with the help of topological information. We synthesized amine-terminated 10,12-pentacosadiynoic acid (PCDA) monomer (PCDA-NH 2 ) and used this derivatized monomer to prepare PCDA liposomes. PCDA-NH 2 liposomes were immobilized on an aldehyde-functionalized glass surface followed by photopolymerization by using a 254 nm light source. To measure the biotin-streptavidin binding, we conjugated photoactivatable biotin to immobilized PCDA-NH 2 liposomes by UV irradiation (365 nm) and subsequently allowed them to interact with streptavidin. We analyzed the fluorescence using a fluorescence scanner and observed single liposomes using NSOM. The average height and NSOM signal observed in a single liposome after binding were ∼31.3 to 8.5 ± 0.5 nm and 0.37 to 0.16 ± 0.6 kHz, respectively. This approach, which has the advantage of not requiring a fluorescent label, could prove highly beneficial for single molecule detection technology

Pupil-segmentation-based adaptive optics for microscopy

Science.gov (United States)

Ji, Na; Milkie, Daniel E.; Betzig, Eric

2011-03-01

Inhomogeneous optical properties of biological samples make it difficult to obtain diffraction-limited resolution in depth. Correcting the sample-induced optical aberrations needs adaptive optics (AO). However, the direct wavefront-sensing approach commonly used in astronomy is not suitable for most biological samples due to their strong scattering of light. We developed an image-based AO approach that is insensitive to sample scattering. By comparing images of the sample taken with different segments of the pupil illuminated, local tilt in the wavefront is measured from image shift. The aberrated wavefront is then obtained either by measuring the local phase directly using interference or with phase reconstruction algorithms similar to those used in astronomical AO. We implemented this pupil-segmentation-based approach in a two-photon fluorescence microscope and demonstrated that diffraction-limited resolution can be recovered from nonbiological and biological samples.

Optical chromatography using a photonic crystal fiber with on-chip fluorescence excitation

CSIR Research Space (South Africa)

Ashok, AC

2010-03-01

Full Text Available The authors describe the realization of integrated optical chromatography, in conjunction with on-chip fluorescence excitation, in a monolithically fabricated poly-dimethylsiloxane (PDMS) microfluidic chip. The unique endlessly-single-mode guiding...

Advances in Spiropyrans/Spirooxazines and Applications Based on Fluorescence Resonance Energy Transfer (FRET with Fluorescent Materials

Directory of Open Access Journals (Sweden)

Hongyan Xia

2017-12-01

Full Text Available Studies on the following were reviewed: (1 the structure of spiropyrans and spirooxazines (two kinds of spiro compounds under external stimuli and (2 the construction and applications of composite systems based on fluorescence resonance energy transfer (FRET with fluorescent materials. When treated with different stimuli (light, acids and bases, solvents, metal ions, temperature, redox potential, and so on, spiropyrans/spirooxazines undergo transformations between the ring-closed form (SP, the ring-opened merocyanine (MC form, and the protonated ring-opened form (MCH. This is due to the breakage of the spiro C–O bond and the protonation of MC, along with a color change. Various novel, multifunctional materials based on photochromic spiropyrans and spirooxazines have been successfully developed because of the vastly differently physiochemical properties posssed by the SP, MC and MCH forms. Among the three different structural forms, the MC form has been studied most extensively. The MC form not only gives complexes with various inorganic particles, biological molecules, and organic chemicals but also acts as the energy acceptor (of energy from fluorescent molecules during energy transfer processes that take place under proper conditions. Furthermore, spiropyran and spirooxazine compounds exhibit reversible physicochemical property changes under proper stimuli; this provides more advantages compared with other photochromic compounds. Additionally, the molecular structures of spiropyrans and spirooxazines can be easily modified and extended, so better compounds can be obtained to expand the scope of already known applications. Described in detail are: (1 the structural properties of spiropyrans and spirooxazines and related photochromic mechanisms; (2 composite systems based on spiropyrans and spirooxazines, and (3 fluorescent materials which have potential applications in sensing, probing, and a variety of optical elements.

Multimodal optical coherence tomography and fluorescence lifetime imaging with interleaved excitation sources for simultaneous endogenous and exogenous fluorescence.

Science.gov (United States)

Shrestha, Sebina; Serafino, Michael J; Rico-Jimenez, Jesus; Park, Jesung; Chen, Xi; Zhaorigetu, Siqin; Walton, Brian L; Jo, Javier A; Applegate, Brian E

2016-09-01

Multimodal imaging probes a variety of tissue properties in a single image acquisition by merging complimentary imaging technologies. Exploiting synergies amongst the data, algorithms can be developed that lead to better tissue characterization than could be accomplished by the constituent imaging modalities taken alone. The combination of optical coherence tomography (OCT) with fluorescence lifetime imaging microscopy (FLIM) provides access to detailed tissue morphology and local biochemistry. The optical system described here merges 1310 nm swept-source OCT with time-domain FLIM having excitation at 355 and 532 nm. The pulses from 355 and 532 nm lasers have been interleaved to enable simultaneous acquisition of endogenous and exogenous fluorescence signals, respectively. The multimodal imaging system was validated using tissue phantoms. Nonspecific tagging with Alexa Flour 532 in a Watanbe rabbit aorta and active tagging of the LOX-1 receptor in human coronary artery, demonstrate the capacity of the system for simultaneous acquisition of OCT, endogenous FLIM, and exogenous FLIM in tissues.

Molecular imaging needles: dual-modality optical coherence tomography and fluorescence imaging of labeled antibodies deep in tissue

Science.gov (United States)

Scolaro, Loretta; Lorenser, Dirk; Madore, Wendy-Julie; Kirk, Rodney W.; Kramer, Anne S.; Yeoh, George C.; Godbout, Nicolas; Sampson, David D.; Boudoux, Caroline; McLaughlin, Robert A.

2015-01-01

Molecular imaging using optical techniques provides insight into disease at the cellular level. In this paper, we report on a novel dual-modality probe capable of performing molecular imaging by combining simultaneous three-dimensional optical coherence tomography (OCT) and two-dimensional fluorescence imaging in a hypodermic needle. The probe, referred to as a molecular imaging (MI) needle, may be inserted tens of millimeters into tissue. The MI needle utilizes double-clad fiber to carry both imaging modalities, and is interfaced to a 1310-nm OCT system and a fluorescence imaging subsystem using an asymmetrical double-clad fiber coupler customized to achieve high fluorescence collection efficiency. We present, to the best of our knowledge, the first dual-modality OCT and fluorescence needle probe with sufficient sensitivity to image fluorescently labeled antibodies. Such probes enable high-resolution molecular imaging deep within tissue. PMID:26137379

Modulation of a fluorescence switch based on photochromic spirooxazine in composite organic nanoparticles

International Nuclear Information System (INIS)

Sheng Xiaohai; Peng Aidong; Fu Hongbing; Liu Yuanyuan; Zhao Yongsheng; Ma Ying; Yao Jiannian

2007-01-01

We describe a versatile and convenient approach to achieve fluorescence modulation by the preparation of composite nanoparticles (CNPs), based on photochromic 5-methoxy-1,3,3-trimethyl-9'-hydroxyspiroindolinenaphthoxazine (SO), fluorescent 4-(dicyanomethylene)-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM), and emissive-assistant 1,3-bis(pyrene) propane (BPP) molecules, employing doping techniques. The mechanism of the fluorescence switch is the intermolecular energy transfer as supported by both steady-state and time-resolved spectroscopy results. The addition of BPP not only enhances the contrast of the fluorescence signal between the 'ON' and 'OFF' state, but also provides a convenient way to tune the excitation wavelength for reading the fluorescence. High-contrast ON/OFF (20:1) fluorescence switching is successfully implemented in the CNPs and also in a more practical PVA film loaded with the CNPs. This system may represent an alternative to the covalent system in potentially rewritable high-density optical data or image storage utilizing luminescence intensity readout schemes

New x-ray optical system for fluorescence beamline at Hasylab

International Nuclear Information System (INIS)

Falkenberg, G.; Tschentscher, T.

2000-01-01

Beamline L at HASYLAB/DESY is actually dedicated to micro x-ray fluorescence (μ-XRF) experiments using the white beam from a bending magnet of the storage ring DORIS III. To extend the applicability of beamline L to other x-ray fluorescence techniques, such as synchrotron radiation total reflection x-ray fluorescence (SR-TXRF) and micro x-ray absorption near edge structures in fluorescence mode (μ-XANES), new x-ray optics have been designed and are under installation at the moment. The suitability of beamline L for SR-TXRF experiments has been shown previously in a number of studies using temporary setups for beam monochromatization and collimation. The new optical system comprises a slit system, a pair of x-ray mirrors for focussing, collimation and high energy cut-off (12 keV and 30 keV), a double multilayer monochromator for broad bandpass applications (TXRF) and a double perfect-crystal monochromator for spectroscopy (XANES, speciation). The multilayer monochromator will utilize a pair of NiC with a spacing of 4.0 nm for the energy range 2-10 keV and a second pair of WB 4 C with a spacing of 3.0 nm for the range 4-30 keV. To extend the energy range for broad bandpass applications to higher photon energies SiGe gradient crystals are foreseen (ΔE/E ∼ 10 -3 ). For the perfect-crystal monochromator we have chosen a pair of Ge 111 crystals for the energy range 2-10 keV and Si 111 crystals for 7-90 keV. To enable the use of low photon energies down to 2 keV the monochromator vessel is sealed to the ring vacuum by a 25 μm thick carbon window. The mirrors and monochromators deflect the beam vertically and can be moved out of the beam independently. Fixed exit geometry permits the illumination of the same sample spot with different wavelength and energy bands. All optical elements accept the full vertical beam opening in order to enable both vertical and horizontal geometries for sample and detector. (author)

A time-domain fluorescence diffusion optical tomography system for breast tumor diagnosis

Science.gov (United States)

Zhang, Wei; Gao, Feng; Wu, LinHui; Ma, Wenjuan; Yang, Fang; Zhou, Zhongxing; Zhang, Limin; Zhao, Huijuan

2011-02-01

A prototype time-domain fluorescence diffusion optical tomography (FDOT) system using near-infrared light is presented. The system employs two pulsed light sources, 32 source fibers and 32 detection channels, working separately for acquiring the temporal distribution of the photon flux on the tissue surface. The light sources are provided by low power picosecond pulsed diode lasers at wavelengths of 780 nm and 830 nm, and a 1×32-fiber-optic-switch sequentially directs light sources to the object surface through 32 source fibers. The light signals re-emitted from the object are collected by 32 detection fibers connected to four 8×1 fiber-optic-switch and then routed to four time-resolved measuring channels, each of which consists of a collimator, a filter wheel, a photomultiplier tube (PMT) photon-counting head and a time-correlated single photon counting (TCSPC) channel. The performance and efficacy of the designed multi-channel PMT-TCSPC system are assessed by reconstructing the fluorescent yield and lifetime images of a solid phantom.

Structural and dynamical aspects of skin studied by multiphoton excitation fluorescence microscopy-based methods

DEFF Research Database (Denmark)

Bloksgaard, Maria; Brewer, Jonathan R.; Bagatolli, Luis

2013-01-01

' parameters. Specifically, by applying these methods, spatially resolved maps of water dipolar relaxation (generalized polarization function using the 6-lauroyl-2-(N,N-dimethylamino)naphthale probe), activity of protons (fluorescence lifetime imaging using a proton sensitive fluorescence probe--2,7-bis-(2......-carboxyethyl)-5-(and-6)-carboxyfluorescein) and diffusion coefficients of distinct fluorescence probes (raster imaging correlation spectroscopy) can be obtained from different regions of the tissue. Comparative studies of different tissue strata, but also between equivalent regions of normal and abnormal......This mini-review reports on applications of particular multiphoton excitation microscopy-based methodologies employed in our laboratory to study skin. These approaches allow in-depth optical sectioning of the tissue, providing spatially resolved information on specific fluorescence probes...

Effect of capsid proteins to ICG mass ratio on fluorescent quantum yield of virus-resembling optical nano-materials

Science.gov (United States)

Gupta, Sharad; Ico, Gerardo; Matsumura, Paul; Rao, A. L. N.; Vullev, Valentine; Anvari, Bahman

2012-03-01

We recently reported construction of a new type of optical nano-construct composed of genome-depleted plant infecting brome mosaic virus (BMV) doped with Indocyanine green (ICG), an FDA-approved chromophore. We refer to these constructs as optical viral ghosts (OVGs) since only the capsid protein (CP) subunits of BMV remain to encapsulate ICG. To utilize OVGs as effective nano-probes in fluorescence imaging applications, their fluorescence quantum yield needs to be maximized. In this study, we investigate the effect of altering the CP to ICG mass ratio on the fluorescent quantum yield of OVGs. Results of this study provide the basis for construction of OVGs with optimal amounts of CP and ICG to yield maximal fluorescence quantum yield.

Multifocal fluorescence microscope for fast optical recordings of neuronal action potentials.

Science.gov (United States)

Shtrahman, Matthew; Aharoni, Daniel B; Hardy, Nicholas F; Buonomano, Dean V; Arisaka, Katsushi; Otis, Thomas S

2015-02-03

In recent years, optical sensors for tracking neural activity have been developed and offer great utility. However, developing microscopy techniques that have several kHz bandwidth necessary to reliably capture optically reported action potentials (APs) at multiple locations in parallel remains a significant challenge. To our knowledge, we describe a novel microscope optimized to measure spatially distributed optical signals with submillisecond and near diffraction-limit resolution. Our design uses a spatial light modulator to generate patterned illumination to simultaneously excite multiple user-defined targets. A galvanometer driven mirror in the emission path streaks the fluorescence emanating from each excitation point during the camera exposure, using unused camera pixels to capture time varying fluorescence at rates that are ∼1000 times faster than the camera's native frame rate. We demonstrate that this approach is capable of recording Ca(2+) transients resulting from APs in neurons labeled with the Ca(2+) sensor Oregon Green Bapta-1 (OGB-1), and can localize the timing of these events with millisecond resolution. Furthermore, optically reported APs can be detected with the voltage sensitive dye DiO-DPA in multiple locations within a neuron with a signal/noise ratio up to ∼40, resolving delays in arrival time along dendrites. Thus, the microscope provides a powerful tool for photometric measurements of dynamics requiring submillisecond sampling at multiple locations. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Fiber optic fluorescence detection of low-level porphyrin concentrations in preclinical and clinical studies

Science.gov (United States)

Mang, Thomas S.; McGinnis, Carolyn; Khan, S.

1990-07-01

A significant clinical problem in the local treatment of cutaneous metastases of breast cancer (by any modality--surgery, radiation therapy or photodynainic therapy) is the fact that the disease almost always extends beyond the boundary of visible lesions in the form of microscopic deposits. These deposits may be distant from the site of visible disease but are often in close proximity to it and are manifested sooner or later by the development of recurrent lesions at the border of the treated area, thus the "marginal miss" in radiation therapy, the "rim recurrence" in photodynamic therapy, and the "incisional recurrence" following surgical excision. More intelligent use of these treatment modalities demands the ability to detect microscopic deposits of tumor cells using non-invasive methodology. In vivo fluorescence measurements have been made possible by the development of an extremely sensitive fiber optic in vivo fluorescence photometer. The instrument has been used to verify that fluorescence correlated with injected porphyrin levels in various tissues. The delivery of light to excite and detect background fluorescence as well as photosensitizer fluorescence in tissues has been accomplished using two HeNe lasers emitting at 632.8 nm and 612 nm delivered through a single quartz fiber optic. Chopping at different frequencies, contributions of fluorescence may be separated. Fluorescence is picked up via a 400 micron quartz fiber optic positioned appropriately near the target tissue. Validation of these levels was made by extraction of the drug from the tissues with resultant quantitation. Recently, an extensive study was undertaken to determine if fluorescence could be used for the detection of occult, clinically non-palpable metastases in the lymph node of rats. This unique model allowed for the detection of micrometastases in lymph nodes using very low injected doses of the photosensitizer Photofrin II. Data obtained revealed the ability to detect on the order

Developing a novel fiber optic fluorescence device for multiplexed high-throughput cytotoxic screening.

Science.gov (United States)

Lee, Dennis; Barnes, Stephen

2010-01-01

The need for new pharmacological agents is unending. Yet the drug discovery process has changed substantially over the past decade and continues to evolve in response to new technologies. There is presently a high demand to reduce discovery time by improving specific lab disciplines and developing new technology platforms in the area of cell-based assay screening. Here we present the developmental concept and early stage testing of the Ab-Sniffer, a novel fiber optic fluorescence device for high-throughput cytotoxicity screening using an immobilized whole cell approach. The fused silica fibers are chemically functionalized with biotin to provide interaction with fluorescently labeled, streptavidin functionalized alginate-chitosan microspheres. The microspheres are also functionalized with Concanavalin A to facilitate binding to living cells. By using lymphoma cells and rituximab in an adaptation of a well-known cytotoxicity protocol we demonstrate the utility of the Ab-Sniffer for functional screening of potential drug compounds rather than indirect, non-functional screening via binding assay. The platform can be extended to any assay capable of being tied to a fluorescence response including multiple target cells in each well of a multi-well plate for high-throughput screening.

Development and exploitation of optical diagnoses based on radicals fluorescence. Application to automotive engines; Developpement et exploitation de diagnostics optiques bases sur la fluorescence de radicaux. Application aux moteurs automobiles

Energy Technology Data Exchange (ETDEWEB)

Auge, M.

2005-12-15

During this PhD, we have developed an optical technique based on radicals fluorescence. The objective was to obtain more information on combustion phenomena. We first have applied the OH and HCHO PLIF technique simultaneously in laminar premixed counter-flow flames under pressure. With this technique, we have obtained the local heat release rate of the flame and an estimation of the laminar flame speed and the thickness of the flame for different fuels and pressure. We have then applied this technique on a Diesel fuel jet in combustion placed in a high pressure cell to understand the different phenomena occurring. Then PLIF at 355 nm was applied in direct and indirect injection spark ignition engine to detect the unburned. We have demonstrated the high potential of the technique used during this PhD to obtain local heat release rate of a flame. We have also progressed in our comprehension of the phenomena occurring during the combustion processes. (author)

Detection system of capillary array electrophoresis microchip based on optical fiber

Science.gov (United States)

Yang, Xiaobo; Bai, Haiming; Yan, Weiping

2009-11-01

To meet the demands of the post-genomic era study and the large parallel detections of epidemic diseases and drug screening, the high throughput micro-fluidic detection system is needed urgently. A scanning laser induced fluorescence detection system based on optical fiber has been established by using a green laser diode double-pumped solid-state laser as excitation source. It includes laser induced fluorescence detection subsystem, capillary array electrophoresis micro-chip, channel identification unit and fluorescent signal processing subsystem. V-shaped detecting probe composed with two optical fibers for transmitting the excitation light and detecting induced fluorescence were constructed. Parallel four-channel signal analysis of capillary electrophoresis was performed on this system by using Rhodamine B as the sample. The distinction of different samples and separation of samples were achieved with the constructed detection system. The lowest detected concentration is 1×10-5 mol/L for Rhodamine B. The results show that the detection system possesses some advantages, such as compact structure, better stability and higher sensitivity, which are beneficial to the development of microminiaturization and integration of capillary array electrophoresis chip.

Initial idea to use optical flats for x-ray fluorescence analysis and recent applications to diffraction studies

International Nuclear Information System (INIS)

Horiuchi, T.

1993-01-01

Described in this work is the initial idea of using an optical flat for X-ray fluorescence analysis based upon studies of anomalous surface reflection (ASR). To develop total-reflection X-ray fluorescence analysis (TXRF) as one of the most powerful tools for microchemical analysis, various experiments such as the micro-determinations of uranium in sea-water, iron in human blood and rare earth elements in hot spring-water were attempted. Furthermore, the physically interesting experiment on Compton scattering under total-reflection conditions was conducted. Recent applications of the total-reflection phenomenon to diffraction studies, i.e. total-reflection X-ray diffraction (TXRD), are also presented. (author)

Modification of fluorescence and optical properties of Rhodamine B dye doped PVA/Chitosan polymer blend films

Science.gov (United States)

Padmakumari, R.; Ravindrachary, V.; Mahantesha, B. K.; Sagar, Rohan N.; Sahanakumari, R.; Bhajantri, R. F.

2018-05-01

Pure and Rhodamine B doped Poly (vinyl alcohol)/Chitosan composite films are prepared using solution casting method. Fourier transforms infrared spectra (FTIR), Ultraviolet-Visible (UV-Vis), fluorescence studies were used to characterize the prepared polymer films. The FT-IR results show that the appearance of new peaks along with shift in peak positions indicates the interaction of Rhodamine B with PVA-CS blend. Optical absorption edge, band gap and activation energy were determined from UV-Visible studies. The optical absorption edge increases, band gap decreases and activation energy increases with dopant concentration respectively. The corresponding emission spectra were studied using fluorescence spectroscopy. From the fluorescence study the quenching phenomena are observed in emission wavelength range of 607nm-613nm upon excitation with absorption maxima 443nm.

Two-photon induced fluorescence and other optical effects in irradiated and doped fused silica

International Nuclear Information System (INIS)

Kramer, S.D.

1986-07-01

The objective of this program was to assess and identify irradiation techniques which could be used to modify the optical charactistics of doped fused silica. Primary emphasis was placed on determining if gamma ray or neutron bombardment of the glass would enhance certain Raman and nonlinear optical effects. In particular, the effect of irradiation on optical two photon induced fluorescence was studied in detail. The maximum radiation exposures used were 10 6 rads (Si) of gamma rays and neutron fluences of 1 x 10 14 neutrons/cm 2 . The optical measurements were made at room temperature between one and four months after irradiation. The maximum input light intensity was 10 9 watts/cm 2 at a near infrared (1.06 μ) input wavelength which was chosen to lie in a transparent spectral region of the glass. Under these experimental conditions a careful search revealed no detectable two-photon induced fluorescence in the region from 550 to 900 nm. The upper limit for the photon efficiency of this process was determined to be less than 1 x 10 -10 %. 89 refs., 12 figs

Fluorescence suppression using wavelength modulated Raman spectroscopy in fiber-probe-based tissue analysis.

Science.gov (United States)

Praveen, Bavishna B; Ashok, Praveen C; Mazilu, Michael; Riches, Andrew; Herrington, Simon; Dholakia, Kishan

2012-07-01

In the field of biomedical optics, Raman spectroscopy is a powerful tool for probing the chemical composition of biological samples. In particular, fiber Raman probes play a crucial role for in vivo and ex vivo tissue analysis. However, the high-fluorescence background typically contributed by the auto fluorescence from both a tissue sample and the fiber-probe interferes strongly with the relatively weak Raman signal. Here we demonstrate the implementation of wavelength-modulated Raman spectroscopy (WMRS) to suppress the fluorescence background while analyzing tissues using fiber Raman probes. We have observed a significant signal-to-noise ratio enhancement in the Raman bands of bone tissue, which have a relatively high fluorescence background. Implementation of WMRS in fiber-probe-based bone tissue study yielded usable Raman spectra in a relatively short acquisition time (∼30  s), notably without any special sample preparation stage. Finally, we have validated its capability to suppress fluorescence on other tissue samples such as adipose tissue derived from four different species.

A trident dithienylethene-perylenemonoimide dyad with super fluorescence switching speed and ratio

Science.gov (United States)

Li, Chong; Yan, Hui; Zhao, Ling-Xi; Zhang, Guo-Feng; Hu, Zhe; Huang, Zhen-Li; Zhu, Ming-Qiang

2014-12-01

Photoswitchable fluorescent diarylethenes are promising in molecular optical memory and photonic devices. However, the performance of current diarylethenes is far from satisfactory because of the scarcity of high-speed switching capability and large fluorescence on-off ratio. Here we report a trident perylenemonoimide dyad modified by triple dithienylethenes whose photochromic fluorescence quenching ratio at the photostationary state exceeds 10,000 and the fluorescence quenching efficiency is close to 100% within seconds of ultraviolet irradiation. The highly sensitive fluorescence on/off switching of the trident dyad enables recyclable fluorescence patterning and all-optical transistors. The prototype optical device based on the trident dyad enables the optical switching of incident light and conversion from incident light wavelength to transmitted light wavelength, which is all-optically controlled, reversible and wavelength-convertible. In addition, the trident dyad-staining block copolymer vesicles are observed via optical nanoimaging with a sub-100 nm resolution, portending a potential prospect of the dithienylethene dyad in super-resolution imaging.

A fluorescence model of the murine lung for optical detection of pathogenic bacteria

Science.gov (United States)

Durkee, Madeleine S.; Cirillo, Jeffrey D.; Maitland, Kristen C.

2017-07-01

We present a computer model of intravital excitation and external fluorescence detection in the murine lungs validated with a three-dimensional lung tissue phantom. The model is applied to optical detection of pulmonary tuberculosis infection.

Modulation of a fluorescence switch based on photochromic spirooxazine in composite organic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Sheng Xiaohai [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Peng Aidong [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Fu Hongbing [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Liu Yuanyuan [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Zhao Yongsheng [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Ma Ying [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Yao Jiannian [Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)

2007-04-11

We describe a versatile and convenient approach to achieve fluorescence modulation by the preparation of composite nanoparticles (CNPs), based on photochromic 5-methoxy-1,3,3-trimethyl-9'-hydroxyspiroindolinenaphthoxazine (SO), fluorescent 4-(dicyanomethylene)-2-methyl-6-(p-dimethyl-aminostyryl)-4H-pyran (DCM), and emissive-assistant 1,3-bis(pyrene) propane (BPP) molecules, employing doping techniques. The mechanism of the fluorescence switch is the intermolecular energy transfer as supported by both steady-state and time-resolved spectroscopy results. The addition of BPP not only enhances the contrast of the fluorescence signal between the 'ON' and 'OFF' state, but also provides a convenient way to tune the excitation wavelength for reading the fluorescence. High-contrast ON/OFF (20:1) fluorescence switching is successfully implemented in the CNPs and also in a more practical PVA film loaded with the CNPs. This system may represent an alternative to the covalent system in potentially rewritable high-density optical data or image storage utilizing luminescence intensity readout schemes.

Optical reading of contaminants in aqueous media based on gold nanoparticles.

Science.gov (United States)

Du, Jianjun; Zhu, Bowen; Peng, Xiaojun; Chen, Xiaodong

2014-09-10

With increasing trends of global population growth, urbanization, pollution over-exploitation, and climate change, the safe water supply has become a global issue and is threatening our society in terms of sustainable development. Therefore, there is a growing need for a water-monitoring platform with the capability of rapidness, specificity, low-cost, and robustness. This review summarizes the recent developments in the design and application of gold nanoparticles (AuNPs) based optical assays to detect contaminants in aqueous media with a high performance. First, a brief discussion on the correlation between the optical reading strategy and the optical properties of AuNPs is presented. Then, we summarize the principle behind AuNP-based optical assays to detect different contaminants, such as toxic metal ion, anion, and pesticides, according to different optical reading strategies: colorimetry, scattering, and fluorescence. Finally, the comparison of these assays and the outlook of AuNP-based optical detection are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection.

Science.gov (United States)

Yao, B C; Wu, Y; Yu, C B; He, J R; Rao, Y J; Gong, Y; Fu, F; Chen, Y F; Li, Y R

2016-03-24

Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel 'FRET on Fiber' concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based 'FRET on fiber' configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated 'FRET on Fiber' sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response.

Optical layout of the fluorescence detector of the Pierre Auger Observatory

Czech Academy of Sciences Publication Activity Database

Palatka, Miroslav; Schovánek, Petr; Hrabovský, Miroslav; Vlček, Martin; Řídký, Jan; Grygar, Jiří; Soukup, Ladislav; Prouza, Michael; Boháčová, Martina

2003-01-01

Roč. 33, 2-3 (2003), s. 445-456 ISSN 0078-5466 R&D Projects: GA MŠk LN00A006; GA MŠk LA 134; GA AV ČR IAA1010928 Institutional research plan: CEZ:AV0Z1010921 Keywords : fluorescence detector * optica l layout Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.221, year: 2003

Optimal model-based sensorless adaptive optics for epifluorescence microscopy.

Science.gov (United States)

Pozzi, Paolo; Soloviev, Oleg; Wilding, Dean; Vdovin, Gleb; Verhaegen, Michel

2018-01-01

We report on a universal sample-independent sensorless adaptive optics method, based on modal optimization of the second moment of the fluorescence emission from a point-like excitation. Our method employs a sample-independent precalibration, performed only once for the particular system, to establish the direct relation between the image quality and the aberration. The method is potentially applicable to any form of microscopy with epifluorescence detection, including the practically important case of incoherent fluorescence emission from a three dimensional object, through minor hardware modifications. We have applied the technique successfully to a widefield epifluorescence microscope and to a multiaperture confocal microscope.

Double-gated spectral snapshots for biomolecular fluorescence

International Nuclear Information System (INIS)

Nakamura, Ryosuke; Hamada, Norio; Ichida, Hideki; Tokunaga, Fumio; Kanematsu, Yasuo

2007-01-01

A versatile method to take femtosecond spectral snapshots of fluorescence has been developed based on a double gating technique in the combination of an optical Kerr gate and an image intensifier as an electrically driven gate set in front of a charge-coupled device detector. The application of a conventional optical-Kerr-gate method is limited to molecules with the short fluorescence lifetime up to a few hundred picoseconds, because long-lifetime fluorescence itself behaves as a source of the background signal due to insufficiency of the extinction ratio of polarizers employed for the Kerr gate. By using the image intensifier with the gate time of 200 ps, we have successfully suppressed the background signal and overcome the application limit of optical-Kerr-gate method. The system performance has been demonstrated by measuring time-resolved fluorescence spectra for laser dye solution and the riboflavin solution as a typical sample of biomolecule

Detection of Biomass in New York City Aerosols: Light Scattering and Optical Fluorescence Techniques

Science.gov (United States)

Niebauer, M.; Alimova, A.; Katz, A.; Xu, M.; Rudolph, E.; Steiner, J.; Alfano, R. R.

2005-12-01

Optical spectroscopy is an ideal method for detecting bacteria and spores in real time. Optical fluorescence spectroscopy examination of New York City aerosols is used to quantify the mass of bacteria spores present in air masses collected at 14 liters/minute onto silica fiber filters, and on silica fiber ribbons using an Environmental Beta Attenuation Monitor manufactured by MetOne Instruments configured for the PM2.5 fraction. Dipicolinic acid (DPA), a molecule found primarily in bacterial spores, is the most characteristic component of spores in trial experiments on over 200 collected aerosol samples. DPA is extracted from the spores using a heat bath and chelated with Terbium. The DPA:Tb is detected by measuring its characteristic fluorescence with emission bands at 490, 545 and 585 nm for 270 nm excitation. Light scattering also measures the size distribution for a number of a variety of bacteria - Bacillus subtilis (rod shaped), Staphylococcus aureus (spherical) and Pseudomonas aeruginosa (short rods) establishing that optical techniques satisfactorily distinguish populations based on their variable morphology. Size and morphology are obtained by applying a variation of the Gaussian Ray Approximation theory of anomalous diffraction theory to an analysis of the transmission spectra in the range of 0.4 to 1.0 microns. In test experiments, the refractive index of the inner spore core of Bacillus subtilis decreases from 1.51 to 1.39 while the spore radius enlarges from 0.38 to 0.6 micrometers. Optical determinations are verified by oil-immersion techniques and by scanning electron microscope measurements. Characterization of spores, germinating spore materials, and bacteria is considered vital to tracing bacteria in the environment, for the development of life-detection systems for planetary exploration, monitoring pathogens in environmental systems, and for the preparation of anti-terrorism strategies.

A new front-face optical cell for measuring weak fluorescent emissions with time resolution in the picosecond time scale.

Science.gov (United States)

Gryczynski, Z; Bucci, E

1993-11-01

Recent developments of ultrafast fluorimeters allow measuring time-resolved fluorescence on the picosecond time scale. This implies one is able to monitor lifetimes and anisotropy decays of highly quenched systems and of systems that contain fluorophores having lifetimes in the subnanosecond range; both systems that emit weak signals. The combination of weak signals and very short lifetimes makes the measurements prone to distortions which are negligible in standard fluorescence experiments. To cope with these difficulties, we have designed a new optical cell for front-face optics which offers to the excitation beam a horizontal free liquid surface in the absence of interactions with optical windows. The new cell has been tested with probes of known lifetimes and anisotropies. It proved very useful in detecting tryptophan fluorescence in hemoglobin. If only diluted samples are available, which cannot be used in front-face optics, regular square geometry can still be utilized by inserting light absorbers into a cuvette of 1 cm path length.

A Pyridazine-Based Fluorescent Probe Targeting Aβ Plaques in Alzheimer’s Disease

Directory of Open Access Journals (Sweden)

Yong Dae Park

2018-01-01

Full Text Available Accumulation of β-amyloid (Aβ plaques comprising Aβ40 and Aβ42 in the brain is the most significant factor in the pathogenesis of Alzheimer’s disease (AD. Thus, the detection of Aβ plaques has increasingly attracted interest in the context of AD diagnosis. In the present study, a fluorescent pyridazine-based dye that can detect and image Aβ plaques was designed and synthesized, and its optical properties in the presence of Aβ aggregates were evaluated. An approximately 34-fold increase in emission intensity was exhibited by the fluorescent probe after binding with Aβ aggregates, for which it showed high affinity (KD = 0.35 µM. Moreover, the reasonable hydrophobic properties of the probe (log P = 2.94 allow it to penetrate the blood brain barrier (BBB. In addition, the pyridazine-based probe was used in the histological costaining of transgenic mouse (APP/PS1 brain sections to validate the selective binding of the probe to Aβ plaques. The results suggest that the pyridazine-based compound has the potential to serve as a fluorescent probe for the diagnosis of AD.

Integrated optical measurement system for fluorescence spectroscopy in microfluidic channels

DEFF Research Database (Denmark)

Hübner, Jörg; Mogensen, Klaus Bo; Jørgensen, Anders Michael

2001-01-01

A transportable miniaturized fiber-pigtailed measurement system is presented which allows quantitative fluorescence detection in microliquid handling systems. The microliquid handling chips are made in silica on silicon technology and the optical functionality is monolithically integrated with th...... with two dyes, fluorescein, and Bodipy 650/665 X, showed good linear behavior over a wide range of concentrations. Minimally detected concentrations were 250 pM for fluorescein and 100 nM for Bodipy....

Video-rate optical flow corrected intraoperative functional fluorescence imaging

NARCIS (Netherlands)

Koch, Maximilian; Glatz, Juergen; Ermolayev, Vladimir; de Vries, Elisabeth G. E.; van Dam, Gooitzen M.; Englmeier, Karl-Hans; Ntziachristos, Vasilis

Intraoperative fluorescence molecular imaging based on targeted fluorescence agents is an emerging approach to improve surgical and endoscopic imaging and guidance. Short exposure times per frame and implementation at video rates are necessary to provide continuous feedback to the physician and

In vivo fluorescence enhanced optical tomography reconstruction of lung cancer of non immersed small animals

Science.gov (United States)

Hervé, L.; Koenig, A.; Da Silva, A.; Berger, M.; Boutet, J.; Dinten, J. M.; Peltié, P.; Rizo, P.

2007-02-01

Fluorescence enhanced diffuse optical tomography (fDOT) is envisioned to be useful to collect functional information from small animal models. For oncology applications, cancer-targeted fluorescent markers can be used as a surrogate of the cancer activity. We are developing a continuous wave fDOT bench intended to be integrated in systems dedicated to whole body small animal fluorescence analyses. The focus is currently put on the reconstruction of non immersed small animals imaged by a CCD camera. The reconstruction stage already corrects the tissue heterogeneity artifacts through the computation of an optical heterogeneity map. We will show how this formalism coupled with the determination of the animal boundaries performed by a laser scanner, can be used to manage non contact acquisitions. The time of reconstruction for a 10 × 9 laser source positions, 45 × 40 detector elements and 14 × 11 × 14 mesh voxels is typically 10 minutes on a 3GHz PCs corresponding to the acquisition time allowing the two tasks to be performed in parallel. The system is validated on an in vivo experiment performed on three healthy nude mice and a mouse bearing a lung tumor at 10, 12 and 14 days after implantation allowing the follow up of the disease. The 3D fluorescence reconstructions of this mouse are presented and the total fluorescence amounts are compared.

Combined fluorescence-Raman spectroscopy measurements with an optical fiber probe for the diagnosis of melanocytic lesions

Science.gov (United States)

Cosci, Alessandro; Cicchi, Riccardo; Rossari, Susanna; De Giorgi, Vincenzo; Massi, Daniela; Pavone, Francesco S.

2012-02-01

We have designed and developed an optical fiber-probe for spectroscopic measurements on human tissues. The experimental setup combines fluorescence spectroscopy and Raman spectroscopy in a multidimensional approach. Concerning fluorescence spectroscopy, the excitation is provided by two laser diodes, one emitting in the UV (378 nm) and the other emitting in the visible (445 nm). These two lasers are used to selectively excite fluorescence from NADH and FAD, which are among the brightest endogenous fluorophores in human tissues. For Raman and NIR spectroscopy, the excitation is provided by a third laser diode with 785 nm excitation wavelength. Laser light is delivered to the tissue through the central optical fiber of a fiber bundle. The surrounding 48 fibers of the bundle are used for collecting fluorescence and Raman and for delivering light to the spectrograph. Fluorescence and Raman spectra are acquired on a cooled CCD camera. The instrument has been tested on fresh human skin biopsies clinically diagnosed as malignant melanoma, melanocytic nevus, or healthy skin, finding an optimal correlation with the subsequent histological exam. In some cases our examination was not in agreement with the clinical observation, but it was with the histological exam, demonstrating that the system can potentially contribute to improve clinical diagnostic capabilities and hence reduce the number of unnecessary biopsies.

Monitoring Cell Death in Regorafenib-Treated Experimental Colon Carcinomas Using Annexin-Based Optical Fluorescence Imaging Validated by Perfusion MRI.

Directory of Open Access Journals (Sweden)

Philipp M Kazmierczak

Full Text Available To investigate annexin-based optical fluorescence imaging (OI for monitoring regorafenib-induced early cell death in experimental colon carcinomas in rats, validated by perfusion MRI and multiparametric immunohistochemistry.Subcutaneous human colon carcinomas (HT-29 in athymic rats (n = 16 were imaged before and after a one-week therapy with regorafenib (n = 8 or placebo (n = 8 using annexin-based OI and perfusion MRI at 3 Tesla. Optical signal-to-noise ratio (SNR and MRI tumor perfusion parameters (plasma flow PF, mL/100mL/min; plasma volume PV, % were assessed. On day 7, tumors underwent immunohistochemical analysis for tumor cell apoptosis (TUNEL, proliferation (Ki-67, and microvascular density (CD31.Apoptosis-targeted OI demonstrated a tumor-specific probe accumulation with a significant increase of tumor SNR under therapy (mean Δ +7.78±2.95, control: -0.80±2.48, p = 0.021. MRI detected a significant reduction of tumor perfusion in the therapy group (mean ΔPF -8.17±2.32 mL/100 mL/min, control -0.11±3.36 mL/100 mL/min, p = 0.036. Immunohistochemistry showed significantly more apoptosis (TUNEL; 11392±1486 vs. 2921±334, p = 0.001, significantly less proliferation (Ki-67; 1754±184 vs. 2883±323, p = 0.012, and significantly lower microvascular density (CD31; 107±10 vs. 182±22, p = 0.006 in the therapy group.Annexin-based OI allowed for the non-invasive monitoring of regorafenib-induced early cell death in experimental colon carcinomas, validated by perfusion MRI and multiparametric immunohistochemistry.

Depth-resolved imaging of colon tumor using optical coherence tomography and fluorescence laminar optical tomography (Conference Presentation)

Science.gov (United States)

Tang, Qinggong; Frank, Aaron; Wang, Jianting; Chen, Chao-wei; Jin, Lily; Lin, Jon; Chan, Joanne M.; Chen, Yu

2016-03-01

Early detection of neoplastic changes remains a critical challenge in clinical cancer diagnosis and treatment. Many cancers arise from epithelial layers such as those of the gastrointestinal (GI) tract. Current standard endoscopic technology is unable to detect those subsurface lesions. Since cancer development is associated with both morphological and molecular alterations, imaging technologies that can quantitative image tissue's morphological and molecular biomarkers and assess the depth extent of a lesion in real time, without the need for tissue excision, would be a major advance in GI cancer diagnostics and therapy. In this research, we investigated the feasibility of multi-modal optical imaging including high-resolution optical coherence tomography (OCT) and depth-resolved high-sensitivity fluorescence laminar optical tomography (FLOT) for structural and molecular imaging. APC (adenomatous polyposis coli) mice model were imaged using OCT and FLOT and the correlated histopathological diagnosis was obtained. Quantitative structural (the scattering coefficient) and molecular imaging parameters (fluorescence intensity) from OCT and FLOT images were developed for multi-parametric analysis. This multi-modal imaging method has demonstrated the feasibility for more accurate diagnosis with 87.4% (87.3%) for sensitivity (specificity) which gives the most optimal diagnosis (the largest area under receiver operating characteristic (ROC) curve). This project results in a new non-invasive multi-modal imaging platform for improved GI cancer detection, which is expected to have a major impact on detection, diagnosis, and characterization of GI cancers, as well as a wide range of epithelial cancers.

Characterizing the Utility and Limitations of Repurposing an Open-Field Optical Imaging Device for Fluorescence-Guided Surgery in Head and Neck Cancer Patients.

Science.gov (United States)

Moore, Lindsay S; Rosenthal, Eben L; Chung, Thomas K; de Boer, Esther; Patel, Neel; Prince, Andrew C; Korb, Melissa L; Walsh, Erika M; Young, E Scott; Stevens, Todd M; Withrow, Kirk P; Morlandt, Anthony B; Richman, Joshua S; Carroll, William R; Zinn, Kurt R; Warram, Jason M

2017-02-01

The purpose of this study was to assess the potential of U.S. Food and Drug Administration-cleared devices designed for indocyanine green-based perfusion imaging to identify cancer-specific bioconjugates with overlapping excitation and emission wavelengths. Recent clinical trials have demonstrated potential for fluorescence-guided surgery, but the time and cost of the approval process may impede clinical translation. To expedite this translation, we explored the feasibility of repurposing existing optical imaging devices for fluorescence-guided surgery. Consenting patients (n = 15) scheduled for curative resection were enrolled in a clinical trial evaluating the safety and specificity of cetuximab-IRDye800 (NCT01987375). Open-field fluorescence imaging was performed preoperatively and during the surgical resection. Fluorescence intensity was quantified using integrated instrument software, and the tumor-to-background ratio characterized fluorescence contrast. In the preoperative clinic, the open-field device demonstrated potential to guide preoperative mapping of tumor borders, optimize the day of surgery, and identify occult lesions. Intraoperatively, the device demonstrated robust potential to guide surgical resections, as all peak tumor-to-background ratios were greater than 2 (range, 2.2-14.1). Postresection wound bed fluorescence was significantly less than preresection tumor fluorescence (P open-field imaging device was successfully repurposed to distinguish cancer from normal tissue in the preoperative clinic and throughout surgical resection. This study illuminated the potential for existing open-field optical imaging devices with overlapping excitation and emission spectra to be used for fluorescence-guided surgery. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Alpha-fetoprotein detection by using a localized surface plasmon coupled fluorescence fiber-optic biosensor

Science.gov (United States)

Chang, Ying-Feng; Chen, Ran-Chou; Li, Ying-Chang; Yu, Chih-Jen; Hsieh, Bao-Yu; Chou, Chien

2007-11-01

Alpha-fetoprotein (AFP) detection by using a localized surface plasmon coupled fluorescence (LSPCF) fiber-optic biosensor is setup and experimentally demonstrated. It is based on gold nanoparticle (GNP) and coupled with localized surface plasmon wave on the surface of GNP. In this experiment, the fluorophores are labeled on anti-AFP which are bound to protein A conjugated GNP. Thus, LSPCF is excited with high efficiency in the near field of localized surface plasmon wave. Therefore, not only the sensitivity of LSPCF biosensor is enhanced but also the specific selectivity of AFP is improved. Experimentally, the ability of real time measurement in the range of AFP concentration from 0.1ng/ml to 100ng/ml was detected. To compare with conventional methods such as enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay (RIA), the LSPCF fiber-optic biosensor performs higher or comparable detection sensitivity, respectively.

Probing Contaminant-Induced Alterations in Chlorophyll Fluorescence by AC-Dielectrophoresis-Based 2D-Algal Array

Directory of Open Access Journals (Sweden)

Coralie Siebman

2018-02-01

Full Text Available The investigation of contaminant impact on algae requires rapid and reliable cell collection and optical detection. The capability of alternative current (AC dielectrophoresis (DEP collection of whole cell arrays with combined fluorescence microscopy detection to follow the alterations of chlorophyll fluorescence during environmental contaminant exposure was explored. The application of an AC-field of 100 V cm−1, 100 Hz for 30 min to capture and immobilize the cells of green alga Chlamydomonas reinhardtii in two-dimensional (2D arrays does not induce changes in chlorophyll fluorescence. The results demonstrate that DEP-based 2D-arrays allow non-invasive detection of chlorophyll fluorescence change upon exposure to high concentrations of copper oxide nanoparticles and ionic copper. These results were in agreement with data obtained by flow cytometry used as a comparative method. The tool was also applied to follow the effect of a number of ubiquitous contaminants such as inorganic mercury, methylmercury, and diuron. However, a statistically significant short-term effect was observed only for mercury. Overall, DEP-based 2D-arrays of algal cells with fluorescence detection appear to be suitable for stain-free probing the effects on the photosynthetic microorganisms in highly polluted environment.

A novel pH-sensitive polymeric fluorescent probe: Synthesis, characterization and optical properties

Energy Technology Data Exchange (ETDEWEB)

Chen Dongyun; Xu Qingfeng; Xia Xuewei; Ge Jianfeng [Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu, 215123 (China); Lu Jianmei, E-mail: lujm@suda.edu.cn [Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu, 215123 (China); Li Najun, E-mail: linajun@sina.com [Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Material Science, Soochow University, Suzhou, Jiangsu, 215123 (China)

2010-04-15

A novel initiator containing proflavine derivative moiety, 3,6-dibromo-isobutyramide acridine (DIA), was synthesized and initiated the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). A water-soluble monomer, N,N-dimethylacrylamide (DMAA) was also initiated by DIA for comparison. The obtained fluorescent polymers, PMMA-DIA and PDMAA-DIA, were characterized by {sup 1}H NMR, GPC and TGA. The emission spectra of the fluorescent polymers exhibit obvious changes in color and fluorescence intensity along with pH varied in range of 3.0-9.0. In addition, the obtained polymers present good film-forming capacity and the films also have a high quantum yield and pH response. Both oil-soluble PMMA-DIA and water-soluble PDMAA-DIA have steady optical and chemical properties by containing proflavine moiety in the main chain.

Performance dependence of hybrid x-ray computed tomography/fluorescence molecular tomography on the optical forward problem.

Science.gov (United States)

Hyde, Damon; Schulz, Ralf; Brooks, Dana; Miller, Eric; Ntziachristos, Vasilis

2009-04-01

Hybrid imaging systems combining x-ray computed tomography (CT) and fluorescence tomography can improve fluorescence imaging performance by incorporating anatomical x-ray CT information into the optical inversion problem. While the use of image priors has been investigated in the past, little is known about the optimal use of forward photon propagation models in hybrid optical systems. In this paper, we explore the impact on reconstruction accuracy of the use of propagation models of varying complexity, specifically in the context of these hybrid imaging systems where significant structural information is known a priori. Our results demonstrate that the use of generically known parameters provides near optimal performance, even when parameter mismatch remains.

A Linear Ion Trap with an Expanded Inscribed Diameter to Improve Optical Access for Fluorescence Spectroscopy

Science.gov (United States)

Rajagopal, Vaishnavi; Stokes, Chris; Ferzoco, Alessandra

2018-02-01

We report a custom-geometry linear ion trap designed for fluorescence spectroscopy of gas-phase ions at ambient to cryogenic temperatures. Laser-induced fluorescence from trapped ions is collected from between the trapping rods, orthogonal to the excitation laser that runs along the axis of the linear ion trap. To increase optical access to the ion cloud, the diameter of the round trapping rods is 80% of the inscribed diameter, rather than the roughly 110% used to approximate purely quadrupolar electric fields. To encompass as much of the ion cloud as possible, the first collection optic has a 25.4 mm diameter and a numerical aperture of 0.6. The choice of geometry and collection optics yields 107 detected photons/s from trapped rhodamine 6G ions. The trap is coupled to a closed-cycle helium refrigerator, which in combination with two 50 Ohm heaters enables temperature control to below 25 K on the rod electrodes. The purpose of the instrument is to broaden the applicability of fluorescence spectroscopy of gas-phase ions to cases where photon emission is a minority relaxation pathway. Such studies are important to understand how the microenvironment of a chromophore influences excited state charge transfer processes.

Development of Ultrasonic Modulation Probe for Fluorescence Tomography Based on Acousto-Optic Effect

Directory of Open Access Journals (Sweden)

Trinh Quang Duc

2011-01-01

Full Text Available We have developed an ultrasonic probe for fluorescence modulation to image fluorescence within biological tissues. The probe consists of a focused ultrasonic transducer mounted on actuators for mechanical fan scanning, which can be used in contact with the measuring object aiming for clinical application. The mechanical fan scanning employed in the probe has a beneficial feature of portability. As a result, fluorescent beads, which were localized with the diameter of 2 mm at 20 mm depth in a pork meat tissue, were detected with resolution of 3 mm. The system performance denotes the feasibility of development towards the final goal of ultrasonic fluorescence modulation tomography for clinical applications.

A hyperspectral fluorescence system for 3D in vivo optical imaging

International Nuclear Information System (INIS)

Zavattini, Guido; Vecchi, Stefania; Mitchell, Gregory; Weisser, Ulli; Leahy, Richard M; Pichler, Bernd J; Smith, Desmond J; Cherry, Simon R

2006-01-01

In vivo optical instruments designed for small animal imaging generally measure the integrated light intensity across a broad band of wavelengths, or make measurements at a small number of selected wavelengths, and primarily use any spectral information to characterize and remove autofluorescence. We have developed a flexible hyperspectral imaging instrument to explore the use of spectral information to determine the 3D source location for in vivo fluorescence imaging applications. We hypothesize that the spectral distribution of the emitted fluorescence signal can be used to provide additional information to 3D reconstruction algorithms being developed for optical tomography. To test this hypothesis, we have designed and built an in vivo hyperspectral imaging system, which can acquire data from 400 to 1000 nm with 3 nm spectral resolution and which is flexible enough to allow the testing of a wide range of illumination and detection geometries. It also has the capability to generate a surface contour map of the animal for input into the reconstruction process. In this paper, we present the design of the system, demonstrate the depth dependence of the spectral signal in phantoms and show the ability to reconstruct 3D source locations using the spectral data in a simple phantom. We also characterize the basic performance of the imaging system

Flexible biodegradable citrate-based polymeric step-index optical fiber.

Science.gov (United States)

Shan, Dingying; Zhang, Chenji; Kalaba, Surge; Mehta, Nikhil; Kim, Gloria B; Liu, Zhiwen; Yang, Jian

2017-10-01

Implanting fiber optical waveguides into tissue or organs for light delivery and collection is among the most effective ways to overcome the issue of tissue turbidity, a long-standing obstacle for biomedical optical technologies. Here, we report a citrate-based material platform with engineerable opto-mechano-biological properties and demonstrate a new type of biodegradable, biocompatible, and low-loss step-index optical fiber for organ-scale light delivery and collection. By leveraging the rich designability and processibility of citrate-based biodegradable polymers, two exemplary biodegradable elastomers with a fine refractive index difference and yet matched mechanical properties and biodegradation profiles were developed. Furthermore, we developed a two-step fabrication method to fabricate flexible and low-loss (0.4 db/cm) optical fibers, and performed systematic characterizations to study optical, spectroscopic, mechanical, and biodegradable properties. In addition, we demonstrated the proof of concept of image transmission through the citrate-based polymeric optical fibers and conducted in vivo deep tissue light delivery and fluorescence sensing in a Sprague-Dawley (SD) rat, laying the groundwork for realizing future implantable devices for long-term implantation where deep-tissue light delivery, sensing and imaging are desired, such as cell, tissue, and scaffold imaging in regenerative medicine and in vivo optogenetic stimulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nonlinear-Optical and Fluorescent Properties of Ag Aqueous Colloid Prepared by Silver Nitrate Reduction

Directory of Open Access Journals (Sweden)

Xiaoqiang Zhang

2010-01-01

Full Text Available The nonlinear-optical properties of metal Ag colloidal solutions, which were prepared by the reduction of silver nitrate, were investigated using Z-scan method. Under picosecond 532 nm excitation, the Ag colloidal solution exhibited negative nonlinear refractive index (n2=−5.17×10−4 cm2/W and reverse saturable absorption coefficient (β=4.32 cm/GW. The data fitting result of optical limiting (OL response of metal Ag colloidal solution indicated that the nonlinear absorption was attributed to two-photon absorption effect at 532 nm. Moreover, the fluorescence emission spectra of Ag colloidal solution were recorded under excitations at both 280 nm and 350 nm. Two fluorescence peaks, 336 nm and 543 nm for 280 nm excitation, while 544 nm and 694 nm for 350 nm excitation, were observed.

Optical design of an optical coherence tomography and multispectral fluorescence imaging endoscope to detect early stage ovarian cancer

Science.gov (United States)

Tate, Tyler; Keenan, Molly; Swan, Elizabeth; Black, John; Utzinger, Urs; Barton, Jennifer

2014-12-01

The five year survival rate for ovarian cancer is over 90% if early detection occurs, yet no effective early screening method exists. We have designed and are constructing a dual modality Optical Coherence Tomography (OCT) and Multispectral Fluorescence Imaging (MFI) endoscope to optically screen the Fallopian tube and ovary for early stage cancer. The endoscope reaches the ovary via the natural pathway of the vagina, cervix, uterus and Fallopian tube. In order to navigate the Fallopian tube the endoscope must have an outer diameter of 600 μm, be highly flexible, steerable, tracking and nonperforating. The imaging systems consists of six optical subsystems, two from OCT and four from MFI. The optical subsystems have independent and interrelated design criteria. The endoscope will be tested on realistic tissue models and ex vivo tissue to prove feasibility of future human trials. Ultimately the project aims to provide women the first effective ovarian cancer screening technique.

Optical absorption and fluorescence spectroscopy studies of Artepillin C, the major component of green propolis

Science.gov (United States)

Camuri, Isamara Julia; Costa, Adriano Batista; Ito, Amando Siuiti; Pazin, Wallance Moreira

2018-06-01

The bioactivity of propolis against several pathogens is well established, leading to the extensive consumption of that bee product to prevent diseases. Brazilian green propolis, collected by the species Apis mellifera, is one of the most consumed in the world. The chemical composition of green propolis is complex and it has been shown that it displays antioxidant, antimicrobial, anti-inflammatory and antitumor activities, especially due to the high content of Artepillin C. The molecule is a derivative of cinnamic acid with two prenylated groups, responsible for the improvement of the affinity of the compound for lipophilic environment. A carboxylic group (COOH) is also present in the molecule, making it a pH-sensitive compound and the pH-dependent structure of Artepillin C, may modulate its biological activity related to interactions with the cellular membrane of organisms and tissues. Molecular properties of Artepillin C on aqueous solution were examined by optical absorption, steady state and time-resolved fluorescence spectroscopies. Acid-base titration based on the spectral position of the near UV absorption band, resulted in the pKa value of 4.65 for the carboxylic group in Artepillin C. In acidic pH, below the pKa value, an absorption band raised around 350 nm at Artepillin C concentration above 50 μM, due to aggregation of the molecule. In neutral pH, with excitation at 310 nm, Artepillin C presents dual emission at 400 and 450 nm. In pH close to the pKa, the optical spectra show contribution from both protonated and deprotonated species. A three-exponential function was necessary to fit the intensity decays at the different pHs, dominated by a very short lifetime component, around 0.060 ns. The fast decay resulted in emission before fluorescence depolarization, and in values of fluorescence anisotropy higher than could be expected for monomeric forms of the compound. The results give fundamental knowledge about the protonation-deprotonation state of the

Comparative study of protoporphyrin IX fluorescence image enhancement methods to improve an optical imaging system for oral cancer detection

Science.gov (United States)

Jiang, Ching-Fen; Wang, Chih-Yu; Chiang, Chun-Ping

2011-07-01

Optoelectronics techniques to induce protoporphyrin IX fluorescence with topically applied 5-aminolevulinic acid on the oral mucosa have been developed to noninvasively detect oral cancer. Fluorescence imaging enables wide-area screening for oral premalignancy, but the lack of an adequate fluorescence enhancement method restricts the clinical imaging application of these techniques. This study aimed to develop a reliable fluorescence enhancement method to improve PpIX fluorescence imaging systems for oral cancer detection. Three contrast features, red-green-blue reflectance difference, R/B ratio, and R/G ratio, were developed first based on the optical properties of the fluorescence images. A comparative study was then carried out with one negative control and four biopsy confirmed clinical cases to validate the optimal image processing method for the detection of the distribution of malignancy. The results showed the superiority of the R/G ratio in terms of yielding a better contrast between normal and neoplastic tissue, and this method was less prone to errors in detection. Quantitative comparison with the clinical diagnoses in the four neoplastic cases showed that the regions of premalignancy obtained using the proposed method accorded with the expert's determination, suggesting the potential clinical application of this method for the detection of oral cancer.

Two-photon excited UV fluorescence for protein crystal detection

International Nuclear Information System (INIS)

Madden, Jeremy T.; DeWalt, Emma L.; Simpson, Garth J.

2011-01-01

Complementary measurements using SONICC and TPE-UVF allow the sensitive and selective detection of protein crystals. Two-photon excited ultraviolet fluorescence (TPE-UVF) microscopy is explored for sensitive protein-crystal detection as a complement to second-order nonlinear optical imaging of chiral crystals (SONICC). Like conventional ultraviolet fluorescence (UVF), TPE-UVF generates image contrast based on the intrinsic fluorescence of aromatic residues, generally producing higher fluorescence emission within crystals than the mother liquor by nature of the higher local protein concentration. However, TPE-UVF has several advantages over conventional UVF, including (i) insensitivity to optical scattering, allowing imaging in turbid matrices, (ii) direct compatibility with conventional optical plates and windows by using visible light for excitation, (iii) elimination of potentially damaging out-of-plane UV excitation, (iv) improved signal to noise through background reduction from out-of-plane excitation and (v) relatively simple integration into instrumentation developed for SONICC

Optical-based molecular imaging: contrast agents and potential medical applications

International Nuclear Information System (INIS)

Bremer, Christoph; Ntziachristos, Vasilis; Weissleder, Ralph

2003-01-01

Laser- and sensitive charge-coupled device technology together with advanced mathematical modelling of photon propagation in tissue has prompted the development of novel optical imaging technologies. Fast surface-weighted imaging modalities, such as fluorescence reflectance imaging (FRI) and 3D quantitative fluorescence-mediated tomography have now become available [1, 2]. These technical advances are paralleled by a rapid development of a whole range of new optical contrasting strategies, which are designed to generate molecular contrast within a living organism. The combination of both, technical advances of light detection and the refinement of optical contrast media, finally yields a new spectrum of tools for in vivo molecular diagnostics. Whereas the technical aspects of optical imaging are covered in more detail in a previous review article in ''European Radiology'' [3], this article focuses on new developments in optical contrasting strategies and design of optical contrast agents for in vivo diagnostics. (orig.)

A comparative study of oxygen transmission rates through polymer films based on fluorescence quenching

DEFF Research Database (Denmark)

Siró, Istvan; Plackett, David; Sommer-Larsen, Peter

2010-01-01

Information on oxygen permeability through polymer films is essential for some applications, especially in food packaging where the control of oxygen levels can be critical in avoiding food spoilage. A permeability testing device using fluorescence-based optical oxygen sensing was developed...... as a potential new instrument for measuring the oxygen permeability of packaging films. The fluorescence-based permeability tester was validated against two existing commercial oxygen permeability measuring devices, the Mocon Ox-Tran 2/20 and PBI-Dansensor OPT-5000. Oxygen transmission rates (OTR) of polylactide...... (PLA) and nanoclay-reinforced PLA films, as well as polyethylene/poly(ethylene terephthalate) (PE/PET) and polypropylene/poly(ethylene terephthalate) (PP/PET) laminated films were determined at 23°C and 50% relative humidity using each of these instruments. No significant differences were observed...

An electronically tunable ultrafast laser source applied to fluorescence imaging and fluorescence lifetime imaging microscopy

International Nuclear Information System (INIS)

Dunsby, C; Lanigan, P M P; McGinty, J; Elson, D S; Requejo-Isidro, J; Munro, I; Galletly, N; McCann, F; Treanor, B; Oenfelt, B; Davis, D M; Neil, M A A; French, P M W

2004-01-01

Fluorescence imaging is used widely in microscopy and macroscopic imaging applications for fields ranging from biomedicine to materials science. A critical component for any fluorescence imaging system is the excitation source. Traditionally, wide-field systems use filtered thermal or arc-generated white light sources, while point scanning confocal microscope systems require spatially coherent (point-like) laser sources. Unfortunately, the limited range of visible wavelengths available from conventional laser sources constrains the design and usefulness of fluorescent probes in confocal microscopy. A 'hands-off' laser-like source, electronically tunable across the visible spectrum, would be invaluable for fluorescence imaging and provide new opportunities, e.g. automated excitation fingerprinting and in situ measurement of excitation cross-sections. Yet more information can be obtained using fluorescence lifetime imaging (FLIM), which requires that the light source be pulsed or rapidly modulated. We show how a white light continuum, generated by injecting femtosecond optical radiation into a micro-structured optical fibre, coupled with a simple prism-based tunable filter arrangement, can fulfil all these roles as a continuously electronically tunable (435-1150 nm) visible ultrafast light source in confocal, wide-field and FLIM systems

Fluorescence detection of single molecules using pulsed near-field optical excitation and time correlated photon counting

International Nuclear Information System (INIS)

Ambrose, W.P.; Goodwin, P.M.; Martin, J.C.; Keller, R.A.

1994-01-01

Pulsed excitation, time correlated single photon counting and time gated detection are used in near-field optical microscopy to enhance fluorescence images and measure the fluorescence lifetimes of single molecules of Rhodamine 6G on silica surfaces. Time gated detection is used to reject prompt scattered background and to improve the image signal to noise ratio. The excited state lifetime of a single Rhodamine 6G molecule is found to depend on the position of the near-field probe. We attribute the lifetime variations to spontaneous emission rate alterations by the fluorescence reflected from and quenching by the aluminum coated probe

Optical Fiber Sensors Based on Nanoparticle-Embedded Coatings

Directory of Open Access Journals (Sweden)

Aitor Urrutia

2015-01-01

Full Text Available The use of nanoparticles (NPs in scientific applications has attracted the attention of many researchers in the last few years. The use of NPs can help researchers to tune the physical characteristics of the sensing coating (thickness, roughness, specific area, refractive index, etc. leading to enhanced sensors with response time or sensitivity better than traditional sensing coatings. Additionally, NPs also offer other special properties that depend on their nanometric size, and this is also a source of new sensing applications. This review focuses on the current status of research in the use of NPs within coatings in optical fiber sensing. Most used sensing principles in fiber optics are briefly described and classified into several groups: absorbance-based sensors, interferometric sensors, fluorescence-based sensors, fiber grating sensors, and resonance-based sensors, among others. For each sensor group, specific examples of the utilization of NP-embedded coatings in their sensing structure are reported.

Plasmonic Nanomaterial-Based Optical Biosensing Platforms for Virus Detection

Directory of Open Access Journals (Sweden)

Jaewook Lee

2017-10-01

Full Text Available Plasmonic nanomaterials (P-NM are receiving attention due to their excellent properties, which include surface-enhanced Raman scattering (SERS, localized surface plasmon resonance (LSPR effects, plasmonic resonance energy transfer (PRET, and magneto optical (MO effects. To obtain such plasmonic properties, many nanomaterials have been developed, including metal nanoparticles (MNP, bimetallic nanoparticles (bMNP, MNP-decorated carbon nanotubes, (MNP-CNT, and MNP-modified graphene (MNP-GRP. These P-NMs may eventually be applied to optical biosensing systems due to their unique properties. Here, probe biomolecules, such as antibodies (Ab, probe DNA, and probe aptamers, were modified on the surface of plasmonic materials by chemical conjugation and thiol chemistry. The optical property change in the plasmonic nanomaterials was monitored based on the interaction between the probe biomolecules and target virus. After bioconjugation, several optical properties, including fluorescence, plasmonic absorbance, and diffraction angle, were changed to detect the target biomolecules. This review describes several P-NMs as potential candidates of optical sensing platforms and introduces various applications in the optical biosensing field.

Design of near-infrared fluorescent bioactive conjugated functional iron oxide nanoparticles for optical detection of colon cancer

Directory of Open Access Journals (Sweden)

Corem-Salkmon E

2012-10-01

Full Text Available Enav Corem-Salkmon, Benny Perlstein, Shlomo MargelThe Institute of Nanotechnology and Advanced Materials, Department of Chemistry, Bar-Ilan University, Ramat-Gan, IsraelBackground: Colon cancer is one of the major causes of death in the Western world. Early detection significantly improves long-term survival for patients with the disease. Near-infrared (NIR fluorescent nanoparticles hold great promise as contrast agents for tumor detection. NIR offers several advantages for bioimaging compared with fluorescence in the visible spectrum, ie, lower autofluorescence of biological tissues, lower absorbance, and consequently deeper penetration into biomatrices.Methods and results: NIR fluorescent iron oxide nanoparticles with a narrow size distribution were prepared by nucleation, followed by controlled growth of thin iron oxide films onto cyanine NIR dye conjugated gelatin-iron oxide nuclei. For functionalization, and in order to increase the NIR fluorescence intensity, the NIR fluorescent iron oxide nanoparticles obtained were coated with human serum albumin containing cyanine NIR dye. Leakage of the NIR dye from these nanoparticles into phosphate-buffered saline solution containing 4% albumin was not detected. The work presented here is a feasibility study to test the suitability of iron oxide-human serum albumin NIR fluorescent nanoparticles for optical detection of colon cancer. It demonstrates that encapsulation of NIR fluorescent dye within these nanoparticles significantly reduces photobleaching of the dye. Tumor-targeting ligands, peanut agglutinin and anticarcinoembryonic antigen antibodies (αCEA, were covalently conjugated with the NIR fluorescent iron oxide-human serum albumin nanoparticles via a poly(ethylene glycol spacer. Specific colon tumor detection was demonstrated in chicken embryo and mouse models for both nonconjugated and the peanut agglutinin-conjugated or αCEA-conjugated NIR fluorescent iron oxide-human serum albumin

Spectral Neugebauer-based color halftone prediction model accounting for paper fluorescence.

Science.gov (United States)

Hersch, Roger David

2014-08-20

We present a spectral model for predicting the fluorescent emission and the total reflectance of color halftones printed on optically brightened paper. By relying on extended Neugebauer models, the proposed model accounts for the attenuation by the ink halftones of both the incident exciting light in the UV wavelength range and the emerging fluorescent emission in the visible wavelength range. The total reflectance is predicted by adding the predicted fluorescent emission relative to the incident light and the pure reflectance predicted with an ink-spreading enhanced Yule-Nielsen modified Neugebauer reflectance prediction model. The predicted fluorescent emission spectrum as a function of the amounts of cyan, magenta, and yellow inks is very accurate. It can be useful to paper and ink manufacturers who would like to study in detail the contribution of the fluorescent brighteners and the attenuation of the fluorescent emission by ink halftones.

Fluorescence-based calculus detection using a 405-nm excitation wavelength

Science.gov (United States)

Brede, O.; Schelle, F.; Krueger, S.; Oehme, B.; Dehn, C.; Frentzen, M.; Braun, A.

2011-03-01

The aim of this study was to assess the difference of fluorescence signals of cement and calculus using a 405 nm excitation wavelength. A total number of 20 freshly extracted teeth was used. The light source used for this study was a blue LED with a wavelength of 405nm. For each tooth the spectra of calculus and cementum were measured separately. Fluorescence light was collimated into an optical fibre and spectrally analyzed using an echelle spectrometer (aryelle 200, Lasertechnik Berlin, Germany) with an additionally bandpass (fgb 67, Edmund Industrial Optics, Karlsruhe, Germany). From these 40 measurements the median values were calculated over the whole spectrum, leading to two different median spectra, one for calculus and one for cementum. For further statistical analysis we defined 8 areas of interest (AOI) in wavelength regions, showing remarkable differences in signal strength. In 7 AOIs the intensity of the calculus spectrum differed statistically significant from the intensity of the cementum spectrum (p calculus and cement between 600nm and 700nm. Thus, we can conclude that fluorescence of calculus shows a significant difference to the fluorescence of cement. A differentiation over the intensity is possible as well as over the spectrum. Using a wavelength of 405nm, it is possible to distinguish between calculus and cement. These results could be used for further devices to develop a method for feedback controlled calculus removal.

Optical-sectioning microscopy of protoporphyrin IX fluorescence in human gliomas: standardization and quantitative comparison with histology

Science.gov (United States)

Wei, Linpeng; Chen, Ye; Yin, Chengbo; Borwege, Sabine; Sanai, Nader; Liu, Jonathan T. C.

2017-04-01

Systemic delivery of 5-aminolevulinic acid leads to enhanced fluorescence image contrast in many tumors due to the increased accumulation of protoporphyrin IX (PpIX), a fluorescent porphyrin that is associated with tumor burden and proliferation. The value of PpIX-guided resection of malignant gliomas has been demonstrated in prospective randomized clinical studies in which a twofold greater extent of resection and improved progression-free survival have been observed. In low-grade gliomas and at the diffuse infiltrative margins of all gliomas, PpIX fluorescence is often too weak to be detected with current low-resolution surgical microscopes that are used in operating rooms. However, it has been demonstrated that high-resolution optical-sectioning microscopes are capable of detecting the sparse and punctate accumulations of PpIX that are undetectable via conventional low-power surgical fluorescence microscopes. To standardize the performance of high-resolution optical-sectioning devices for future clinical use, we have developed an imaging phantom and methods to ensure that the imaging of PpIX-expressing brain tissues can be performed reproducibly. Ex vivo imaging studies with a dual-axis confocal microscope demonstrate that these methods enable the acquisition of images from unsectioned human brain tissues that quantitatively and consistently correlate with images of histologically processed tissue sections.

Radiation imaging with optically read out GEM-based detectors

Science.gov (United States)

Brunbauer, F. M.; Lupberger, M.; Oliveri, E.; Resnati, F.; Ropelewski, L.; Streli, C.; Thuiner, P.; van Stenis, M.

2018-02-01

Modern imaging sensors allow for high granularity optical readout of radiation detectors such as MicroPattern Gaseous Detectors (MPGDs). Taking advantage of the high signal amplification factors achievable by MPGD technologies such as Gaseous Electron Multipliers (GEMs), highly sensitive detectors can be realised and employing gas mixtures with strong scintillation yield in the visible wavelength regime, optical readout of such detectors can provide high-resolution event representations. Applications from X-ray imaging to fluoroscopy and tomography profit from the good spatial resolution of optical readout and the possibility to obtain images without the need for extensive reconstruction. Sensitivity to low-energy X-rays and energy resolution permit energy resolved imaging and material distinction in X-ray fluorescence measurements. Additionally, the low material budget of gaseous detectors and the possibility to couple scintillation light to imaging sensors via fibres or mirrors makes optically read out GEMs an ideal candidate for beam monitoring detectors in high energy physics as well as radiotherapy. We present applications and achievements of optically read out GEM-based detectors including high spatial resolution imaging and X-ray fluorescence measurements as an alternative readout approach for MPGDs. A detector concept for low intensity applications such as X-ray crystallography, which maximises detection efficiency with a thick conversion region but mitigates parallax-induced broadening is presented and beam monitoring capabilities of optical readout are explored. Augmenting high resolution 2D projections of particle tracks obtained with optical readout with timing information from fast photon detectors or transparent anodes for charge readout, 3D reconstruction of particle trajectories can be performed and permits the realisation of optically read out time projection chambers. Combining readily available high performance imaging sensors with compatible

Optical scanner system for high resolution measurement of lubricant distributions on metal strips based on laser induced fluorescence

Science.gov (United States)

Holz, Philipp; Lutz, Christian; Brandenburg, Albrecht

2017-06-01

We present a new optical setup, which uses scanning mirrors in combination with laser induced fluorescence to monitor the spatial distribution of lubricant on metal sheets. Current trends in metal processing industry require forming procedures with increasing deformations. Thus a welldefined amount of lubricant is necessary to prevent the material from rupture, to reduce the wearing of the manufacturing tool as well as to prevent problems in post-deforming procedures. Therefore spatial resolved analysis of the thickness of lubricant layers is required. Current systems capture the lubricant distribution by moving sensor heads over the object along a linear axis. However the spatial resolution of these systems is insufficient at high strip speeds, e.g. at press plants. The presented technology uses fast rotating scanner mirrors to deflect a laser beam on the surface. This 405 nm laser light excites the autofluorescence of the investigated lubricants. A coaxial optic collects the fluorescence signal which is then spectrally filtered and recorded using a photomultiplier. From the acquired signal a two dimensional image is reconstructed in real time. This paper presents the sensor setup as well as its characterization. For the calibration of the system reference targets were prepared using an ink jet printer. The presented technology for the first time allows a spatial resolution in the millimetre range at production speed. The presented test system analyses an area of 300 x 300 mm² at a spatial resolution of 1.1 mm in less than 20 seconds. Despite this high speed of the measurement the limit of detection of the system described in this paper is better than 0.05 g/m² for the certified lubricant BAM K-009.

Fluorescence spectroscopy for medical and environmental diagnostics

International Nuclear Information System (INIS)

Johansson, Jonas.

1993-09-01

Fluorescence spectroscopy can be used for diagnostics in medical and environmental applications. The many aspects of fluorescence emission are utilized to enhance the accuracy of the diagnosis. A fluorescence detection system, based on nitrogen laser or dye laser excitation and optical multichannel detection, was constructed, and fluorescence spectra from human malignant tumours of various origins, were recorded. Tumour demarcation was observed using exogenous chromophores, as well as the endogenous tissue fluorescence. In particular, δ-amino levulinic acid was found to provide very good tumour demarcation. A multi-colour imaging system capable of simultaneous recording of four fluorescence images at selected wavelengths, was developed. Examples of processed images, based on the four sub-images, are shown for malignant tumours. In addition, data from photodynamic treatment of human malignant tumours are presented. Autofluorescence spectra from excised pieces of human atherosclerotic aorta and atherosclerotic coronary segment were found to be different from those of non-diseased vessels. Furthermore, fluorescence decay curves from atherosclerotic samples were found to differ from those of non-diseased samples. It is concluded that both spectral and temporal information should be utilized to enhance the demarcation. Methods for obtaining fluorescence data free from interference from blood, with applications to in vivo laser angioplasty of atherosclerosis, are discussed. The optical multichannel system and the multi-colour imaging system were integrated with a remote sensing system, originally used for environmental measurements, to obtain fluorescence spectra as well as fluorescence images of plants at a distance of up to 100 m. The fluorescence data from plants subject to environmental stress or senescent plants were found to differ from those obtained from healthy vegetation. 359 refs

Molecular Imaging of β-Amyloid Plaques with Near-Infrared Boron Dipyrromethane (BODIPY-Based Fluorescent Probes

Directory of Open Access Journals (Sweden)

Hiroyuki Watanabe

2013-07-01

Full Text Available The formation of β-amyloid (Aβ plaques is a critical neurodegenerative change in Alzheimer disease (AD. We designed and synthesized novel boron dipyrromethane (BODIPY-based Aβ probes (BAPs and evaluated their utility for near-infrared fluorescence imaging of Aβ plaques in the brain. In binding experiments in vitro, BAPs showed high affinity for synthetic Aβ aggregates (Kd = 18–149 nM. Furthermore, BAPs clearly stained Aβ plaques in sections of Tg2576 mice. In mouse brain tissue, BAPs showed sufficient uptake for optical imaging. In addition, ex vivo fluorescent staining of brain sections from Tg2576 mice after the injection of BAP-2 showed selective binding of Aβ plaques with little nonspecific binding. BAPs may be useful as a near-infrared fluorescent probe for imaging Aβ plaques.

Chemosensors and biosensors based on polyelectrolyte microcapsules containing fluorescent dyes and enzymes.

Science.gov (United States)

Kazakova, Lyubov I; Shabarchina, Lyudmila I; Anastasova, Salzitsa; Pavlov, Anton M; Vadgama, Pankaj; Skirtach, Andre G; Sukhorukov, Gleb B

2013-02-01

The concept of enzyme-assisted substrate sensing based on use of fluorescent markers to detect the products of enzymatic reaction has been investigated by fabrication of micron-scale polyelectrolyte capsules containing enzymes and dyes in one entity. Microcapsules approximately 5 μm in size entrap glucose oxidase or lactate oxidase, with peroxidase, together with the corresponding markers Tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) dichloride (Ru(dpp)) complex and dihydrorhodamine 123 (DHR123), which are sensitive to oxygen and hydrogen peroxide, respectively. These capsules are produced by co-precipitation of calcium carbonate particles with the enzyme followed by layer-by-layer assembly of polyelectrolytes over the surface of the particles and incorporation of the dye in the capsule interior or in the multilayer shell. After dissolution of the calcium carbonate the enzymes and dyes remain in the multilayer capsules. In this study we produced enzyme-containing microcapsules sensitive to glucose and lactate. Calibration curves based on fluorescence intensity of Ru(dpp) and DHR123 were linearly dependent on substrate concentration, enabling reliable sensing in the millimolar range. The main advantages of using these capsules with optical recording is the possibility of building single capsule-based sensors. The response from individual capsules was observed by confocal microscopy as increasing fluorescence intensity of the capsule on addition of lactate at millimolar concentrations. Because internalization of the micron-sized multi-component capsules was feasible, they could be further optimized for in-situ intracellular sensing and metabolite monitoring on the basis of fluorescence reporting.

Fluorescent Biosensors Based on Single-Molecule Counting.

Science.gov (United States)

Ma, Fei; Li, Ying; Tang, Bo; Zhang, Chun-Yang

2016-09-20

Biosensors for highly sensitive, selective, and rapid quantification of specific biomolecules make great contributions to biomedical research, especially molecular diagnostics. However, conventional methods for biomolecular assays often suffer from insufficient sensitivity and poor specificity. In some case (e.g., early disease diagnostics), the concentration of target biomolecules is too low to be detected by these routine approaches, and cumbersome procedures are needed to improve the detection sensitivity. Therefore, there is an urgent need for rapid and ultrasensitive analytical tools. In this respect, single-molecule fluorescence approaches may well satisfy the requirement and hold promising potential for the development of ultrasensitive biosensors. Encouragingly, owing to the advances in single-molecule microscopy and spectroscopy over past decades, the detection of single fluorescent molecule comes true, greatly boosting the development of highly sensitive biosensors. By in vitro/in vivo labeling of target biomolecules with proper fluorescent tags, the quantification of certain biomolecule at the single-molecule level is achieved. In comparison with conventional ensemble measurements, single-molecule detection-based analytical methods possess the advantages of ultrahigh sensitivity, good selectivity, rapid analysis time, and low sample consumption. Consequently, single-molecule detection may be potentially employed as an ideal analytical approach to quantify low-abundant biomolecules with rapidity and simplicity. In this Account, we will summarize our efforts for developing a series of ultrasensitive biosensors based on single-molecule counting. Single-molecule counting is a member of single-molecule detection technologies and may be used as a very simple and ultrasensitive method to quantify target molecules by simply counting the individual fluorescent bursts. In the fluorescent sensors, the signals of target biomolecules may be translated to the

Automatic neutron dosimetry system based on fluorescent nuclear track detector technology

International Nuclear Information System (INIS)

Akselrod, M.S.; Fomenko, V.V.; Bartz, J.A.; Haslett, T.L.

2014-01-01

For the first time, the authors are describing an automatic fluorescent nuclear track detector (FNTD) reader for neutron dosimetry. FNTD is a luminescent integrating type of detector made of aluminium oxide crystals that does not require electronics or batteries during irradiation. Non-destructive optical readout of the detector is performed using a confocal laser scanning fluorescence imaging with near-diffraction limited resolution. The fully automatic table-top reader allows one to load up to 216 detectors on a tray, read their engraved IDs using a CCD camera and optical character recognition, scan and process simultaneously two types of images in fluorescent and reflected laser light contrast to eliminate false-positive tracks related to surface and volume crystal imperfections. The FNTD dosimetry system allows one to measure neutron doses from 0.1 mSv to 20 Sv and covers neutron energies from thermal to 20 MeV. The reader is characterised by a robust, compact optical design, fast data processing electronics and user-friendly software. The first table-top automatic FNTD neutron dosimetry system was successfully tested for LLD, linearity and ability to measure neutrons in mixed neutron-photon fields satisfying US and ISO standards. This new neutron dosimetry system provides advantages over other technologies including environmental stability of the detector material, wide range of detectable neutron energies and doses, detector re-readability and re-usability and all-optical readout. A new adaptive image processing algorithm reliably removes false-positive tracks associated with surface and bulk crystal imperfections. (authors)

A label-free, fluorescence based assay for microarray

Science.gov (United States)

Niu, Sanjun

DNA chip technology has drawn tremendous attention since it emerged in the mid 90's as a method that expedites gene sequencing by over 100-fold. DNA chip, also called DNA microarray, is a combinatorial technology in which different single-stranded DNA (ssDNA) molecules of known sequences are immobilized at specific spots. The immobilized ssDNA strands are called probes. In application, the chip is exposed to a solution containing ssDNA of unknown sequence, called targets, which are labeled with fluorescent dyes. Due to specific molecular recognition among the base pairs in the DNA, the binding or hybridization occurs only when the probe and target sequences are complementary. The nucleotide sequence of the target is determined by imaging the fluorescence from the spots. The uncertainty of background in signal detection and statistical error in data analysis, primarily due to the error in the DNA amplification process and statistical distribution of the tags in the target DNA, have become the fundamental barriers in bringing the technology into application for clinical diagnostics. Furthermore, the dye and tagging process are expensive, making the cost of DNA chips inhibitive for clinical testing. These limitations and challenges make it difficult to implement DNA chip methods as a diagnostic tool in a pathology laboratory. The objective of this dissertation research is to provide an alternative approach that will address the above challenges. In this research, a label-free assay is designed and studied. Polystyrene (PS), a commonly used polymeric material, serves as the fluorescence agent. Probe ssDNA is covalently immobilized on polystyrene thin film that is supported by a reflecting substrate. When this chip is exposed to excitation light, fluorescence light intensity from PS is detected as the signal. Since the optical constants and conformations of ssDNA and dsDNA (double stranded DNA) are different, the measured fluorescence from PS changes for the same

Fluorescent magnetic hybrid nanoprobe for multimodal bioimaging

Energy Technology Data Exchange (ETDEWEB)

Koktysh, Dmitry [Department of Chemistry, Vanderbilt University, Station B 351822, Nashville, TN 37235 (United States); Bright, Vanessa; Pham, Wellington, E-mail: dmitry.koktysh@vanderbilt.edu, E-mail: wellington.pham@vanderbilt.edu [Institute of Imaging Science, Vanderbilt University, 1161 21st Avenue South AA, 1105 MCN, Nashville, TN 37232 (United States)

2011-07-08

A fluorescent magnetic hybrid imaging nanoprobe (HINP) was fabricated by the conjugation of superparamagnetic Fe{sub 3}O{sub 4} nanoparticles and visible light emitting ({approx}600 nm) fluorescent CdTe/CdS quantum dots (QDs). The assembly strategy used the covalent linking of the oxidized dextran shell of magnetic particles to the glutathione ligands of QDs. The synthesized HINP formed stable water-soluble colloidal dispersions. The structure and properties of the particles were characterized by transmission electron and atomic force microscopy, energy dispersive x-ray analysis and inductively coupled plasma optical emission spectroscopy, dynamic light scattering analysis, optical absorption and photoluminescence spectroscopy, and fluorescent imaging. The luminescence imaging region of the nanoprobe was extended to the near-infrared (NIR) ({approx}800 nm) by conjugation of the superparamagnetic nanoparticles with synthesized CdHgTe/CdS QDs. Cadmium, mercury based QDs in HINP can be easily replaced by novel water-soluble glutathione stabilized AgInS{sub 2}/ZnS QDs to present a new class of cadmium-free multimodal imaging agents. The observed NIR photoluminescence of fluorescent magnetic nanocomposites supports their use for bioimaging. The developed HINP provides dual-imaging channels for simultaneous optical and magnetic resonance imaging.

Synthesis and characterization of multicolour fluorescent ...

Indian Academy of Sciences (India)

... of latent fingerprints. The optical and structural characterization of the nanoparticles was carried .... by absorption of phonons from the host matrix [13], the exchange of energy in ... impressions based on the fluorescent properties exhibited by.

Design and fabrication of optical chemical sensor for detection of nitroaromatic explosives based on fluorescence quenching of phenol red immobilized poly(vinyl alcohol) membrane.

Science.gov (United States)

Zarei, Ali Reza; Ghazanchayi, Behnam

2016-04-01

The present study developed a new optical chemical sensor for detection of nitroaromatic explosives in liquid phase. The method is based on the fluorescence quenching of phenol red as fluorophore in a poly(vinyl alcohol) (PVA) membrane in the presence of nitroaromatic explosives as quenchers, e.g., 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (2,4-DNT), 4-nitrotoluene (4-NT), 2,4,6-trinitrobenzene (TNB), and nitrobenzene (NB). For chemical immobilization of phenol red in PVA, phenol red reacted with formaldehyde to produce hydroxymethyl groups and then attached to PVA membrane through the hydroxymethyl groups. The optical sensor showed strong quenching of nitroaromatic explosives. A Stern-Volmer graph for each explosive was constructed and showed that the range of concentration from 5.0 × 10(-6) to 2.5 × 10(-4) mol L(-1) was linear for each explosive and sensitivity varied as TNB >TNT>2,4-DNT>NB>4-NT. The response time of the sensor was within 1 min. The proposed sensor showed good reversibility and reproducibility. Copyright © 2015 Elsevier B.V. All rights reserved.

Theory and development of fluorescence-based optochemical oxygen sensors: oxygen optodes.

Science.gov (United States)

Opitz, N; Lübbers, D W

1987-01-01

As the preceding considerations concerning the physical and technical features of oxygen optodes have demonstrated, fluorescence-based optochemical oxygen sensors possess certain advantages and peculiarities compared to conventionally applied electrochemical sensors such as polarographic oxygen electrodes. First, in contrast to oxygen electrodes, oxygen measurements with oxygen optodes do not suffer from distortions caused by the reference electrodes. In addition, because of the polarographic process, platinum electrodes continuously consume oxygen, which falsifies the results, especially when small sample volumes or long-term measurements, or both, are involved, whereas the sensor layer of oxygen optodes must only be equilibrated. Moreover, the surface of the platinum wire has to be catalytically clean in order to obtain a plateau of the polarogram and, consequently, to achieve a low rest current at zero PO2. Unfortunately, the demand for catalytically clean platinum surfaces turns out to be rather critical, since surface contamination occurs even with membranized electrodes, resulting in the well-known phenomenon of "electrode poisoning." The question of the specificity of oxygen electrodes also must be considered. In this context, CO2 and halothane may interfere with oxygen measurements, whereas fluorescence quenching is unaffected by CO2 and halothane affects the measurements only slightly, depending on the special indicator used. Furthermore, because of the flow dependence, oxygen measurements with the oxygen electrode show a distinct "stirring effect" caused by the turbulence in front of the electrode, which disturbs the diffusion field. Because of the completely different physical principle of fluorescence optical sensors, such influences are not observed with oxygen optodes. In addition, isolation and shielding of electrical circuits found in electrodes are not necessary for optodes. Furthermore, the sensitivity of oxygen optodes can be tuned to the desired

Study of continuous-wave domain fluorescence diffuse optical tomography for quality control on agricultural produce

Energy Technology Data Exchange (ETDEWEB)

Nadhira, Vebi, E-mail: vebi@tf.itb.ac.id; Kurniadi, Deddy, E-mail: vebi@tf.itb.ac.id; Juliastuti, E., E-mail: vebi@tf.itb.ac.id; Sutiswan, Adeline, E-mail: vebi@tf.itb.ac.id [Instrumentation and Control Research Group, Faculty of Industrial Technology, Institute Technology of Bandung, Ganesha 10 40132 Bandung (Indonesia)

2014-03-24

The importance of monitoring the quality of vegetables and fruits is prosperity by giving a competitive advantage for producer and providing a more healthy food for consumer. Diffuse Optical Tomography (DOT) is offering the possibility to detect the internal defects of the agricultural produce quality. Fluorescence diffuse optical tomography (FDOT) is the development of DOT, offering the possibilities to improve spatial resolution and to contrast image. The purpose of this research is to compare FDOT and DOT in forward analysis with continuous wave approach. The scattering and absorbing parameters of potatoes are used to represent the real condition. The object was illuminated by the NIR source from some positions on the boundary of object. A set of NIR detector are placed on the peripheral position of the object to measure the intensity of propagated or emitted light. In the simulation, we varied a condition of object then we analyzed the sensitivity of forward problem. The result of this study shows that FDOT has a better sensitivity than DOT and a better potential to monitor internal defects of agricultural produce because of the contrast value between optical and fluorescence properties of agricultural produce normal tissue and defects.

X-ray fluorescence analysis and optical emission spectrometry of an roman mirror from Tomis, Romania

International Nuclear Information System (INIS)

Belc, M.; Bogoi, M.; Ionescu, D.; Guita, D.; Caiteanu, S.; Caiteanu, D.

2000-01-01

The miscellaneous population of Roman Empire, their diverse cultural tradition, their ability to assimilate the roman civilization spirits, had determined a permanent reassessment superimposed upon the roman contribution. Analysis was undertaken using optical emission spectrometry and non-destructive X-ray fluorescence. X-ray fluorescence analysis is a well-established method and is often used in archaeometry and other work dealing with valuable objects pertaining to the history of art and civilization. Roman mirror analysed has been found not to be made of speculum (a high tin bronze). (authors)

Near infrared spatial frequency domain fluorescence imaging of tumor phantoms containing erythrocyte-derived optical nanoplatforms

Science.gov (United States)

Burns, Joshua M.; Schaefer, Elise; Anvari, Bahman

2018-02-01

Light-activated theranostic constructs provide a multi-functional platform for optical imaging and phototherapeutic applications. Our group has engineered nano-sized vesicles derived from erythrocytes that encapsulate the FDAapproved near infrared (NIR) absorber indocyanine green (ICG). We refer to these constructs as NIR erythrocytemimicking transducers (NETs). Once photo-excited by NIR light these constructs can transduce the photons energy to emit fluorescence, generate heat, or induce chemical reactions. In this study, we investigated fluorescence imaging of NETs embedded within tumor phantoms using spatial frequency domain imaging (SFDI). Using SFDI, we were able to fluorescently image simulated tumors doped with different concentration of NETs. These preliminary results suggest that NETs can be used in conjunction with SFDI for potential tumor imaging applications.

Near-infrared fluorescent aza-BODIPY dye-loaded biodegradable polymeric nanoparticles for optical cancer imaging

International Nuclear Information System (INIS)

Hamon, Casey L.; Dorsey, Christopher L.; Özel, Tuğba; Barnes, Eugenia M.; Hudnall, Todd W.; Betancourt, Tania

2016-01-01

Nanoparticles are being readily investigated as carriers for the delivery of imaging and therapeutic agents for the detection, monitoring, and treatment of cancer and other diseases. In the present work, the preparation of biodegradable polymeric nanoparticles loaded with a near-infrared fluorescent aza-boron dipyrromethene (NIR-BODIPY) derivative, and their use as contrast agents for optical imaging in cancer are described. Nanoparticles were prepared by nanoprecipitation of amphiphilic block copolymers of poly(lactic acid) and poly(ethylene glycol). The size, morphology, dye loading, spectral properties, quantum yield, cytocompatibility, and in vitro NIR imaging potential of the nanoparticles in breast and ovarian cancer cells were evaluated. Spherical nanoparticles of 30–70 nm in diameter were loaded with 0.73 w/w% BODIPY derivative. At this loading, the dye presented a fluorescence quantum yield in the same order of magnitude as in solution. Nanoparticle suspensions at concentrations up to 580 μg/mL were cytocompatible to breast (MDA-MB-231) and ovarian (SKOV-3 and Caov-3) cancer cells after a four-hour incubation period. Fluorescence microscopy images demonstrated the ability of the nanoparticles to act as imaging agents in all three cell lines in as little as 1 hour. The results shown indicate the potential of these NIR-BODIPY-loaded nanoparticles as contrast agents for near-infrared optical imaging in cancer.Graphical abstract

Near-infrared fluorescent aza-BODIPY dye-loaded biodegradable polymeric nanoparticles for optical cancer imaging

Energy Technology Data Exchange (ETDEWEB)

Hamon, Casey L.; Dorsey, Christopher L. [Texas State University, Department of Chemistry and Biochemistry (United States); Özel, Tuğba [Texas State University, Materials Science, Engineering, and Commercialization Program (United States); Barnes, Eugenia M.; Hudnall, Todd W.; Betancourt, Tania, E-mail: tb26@txstate.edu [Texas State University, Department of Chemistry and Biochemistry (United States)

2016-07-15

Nanoparticles are being readily investigated as carriers for the delivery of imaging and therapeutic agents for the detection, monitoring, and treatment of cancer and other diseases. In the present work, the preparation of biodegradable polymeric nanoparticles loaded with a near-infrared fluorescent aza-boron dipyrromethene (NIR-BODIPY) derivative, and their use as contrast agents for optical imaging in cancer are described. Nanoparticles were prepared by nanoprecipitation of amphiphilic block copolymers of poly(lactic acid) and poly(ethylene glycol). The size, morphology, dye loading, spectral properties, quantum yield, cytocompatibility, and in vitro NIR imaging potential of the nanoparticles in breast and ovarian cancer cells were evaluated. Spherical nanoparticles of 30–70 nm in diameter were loaded with 0.73 w/w% BODIPY derivative. At this loading, the dye presented a fluorescence quantum yield in the same order of magnitude as in solution. Nanoparticle suspensions at concentrations up to 580 μg/mL were cytocompatible to breast (MDA-MB-231) and ovarian (SKOV-3 and Caov-3) cancer cells after a four-hour incubation period. Fluorescence microscopy images demonstrated the ability of the nanoparticles to act as imaging agents in all three cell lines in as little as 1 hour. The results shown indicate the potential of these NIR-BODIPY-loaded nanoparticles as contrast agents for near-infrared optical imaging in cancer.Graphical abstract.

Fluorescent sensors based on bacterial fusion proteins

International Nuclear Information System (INIS)

Mateu, Batirtze Prats; Pum, Dietmar; Sleytr, Uwe B; Toca-Herrera, José L; Kainz, Birgit

2014-01-01

Fluorescence proteins are widely used as markers for biomedical and technological purposes. Therefore, the aim of this project was to create a fluorescent sensor, based in the green and cyan fluorescent protein, using bacterial S-layers proteins as scaffold for the fluorescent tag. We report the cloning, expression and purification of three S-layer fluorescent proteins: SgsE-EGFP, SgsE-ECFP and SgsE-13aa-ECFP, this last containing a 13-amino acid rigid linker. The pH dependence of the fluorescence intensity of the S-layer fusion proteins, monitored by fluorescence spectroscopy, showed that the ECFP tag was more stable than EGFP. Furthermore, the fluorescent fusion proteins were reassembled on silica particles modified with cationic and anionic polyelectrolytes. Zeta potential measurements confirmed the particle coatings and indicated their colloidal stability. Flow cytometry and fluorescence microscopy showed that the fluorescence of the fusion proteins was pH dependent and sensitive to the underlying polyelectrolyte coating. This might suggest that the fluorescent tag is not completely exposed to the bulk media as an independent moiety. Finally, it was found out that viscosity enhanced the fluorescence intensity of the three fluorescent S-layer proteins. (paper)

Compact point-detection fluorescence spectroscopy system for quantifying intrinsic fluorescence redox ratio in brain cancer diagnostics

Science.gov (United States)

Liu, Quan; Grant, Gerald; Li, Jianjun; Zhang, Yan; Hu, Fangyao; Li, Shuqin; Wilson, Christy; Chen, Kui; Bigner, Darell; Vo-Dinh, Tuan

2011-03-01

We report the development of a compact point-detection fluorescence spectroscopy system and two data analysis methods to quantify the intrinsic fluorescence redox ratio and diagnose brain cancer in an orthotopic brain tumor rat model. Our system employs one compact cw diode laser (407 nm) to excite two primary endogenous fluorophores, reduced nicotinamide adenine dinucleotide, and flavin adenine dinucleotide. The spectra were first analyzed using a spectral filtering modulation method developed previously to derive the intrinsic fluorescence redox ratio, which has the advantages of insensitivty to optical coupling and rapid data acquisition and analysis. This method represents a convenient and rapid alternative for achieving intrinsic fluorescence-based redox measurements as compared to those complicated model-based methods. It is worth noting that the method can also extract total hemoglobin concentration at the same time but only if the emission path length of fluorescence light, which depends on the illumination and collection geometry of the optical probe, is long enough so that the effect of absorption on fluorescence intensity due to hemoglobin is significant. Then a multivariate method was used to statistically classify normal tissues and tumors. Although the first method offers quantitative tissue metabolism information, the second method provides high overall classification accuracy. The two methods provide complementary capabilities for understanding cancer development and noninvasively diagnosing brain cancer. The results of our study suggest that this portable system can be potentially used to demarcate the elusive boundary between a brain tumor and the surrounding normal tissue during surgical resection.

In-vivo fluorescence detection of breast cancer growth factor receptors by fiber-optic probe

Science.gov (United States)

Bustamante, Gilbert; Wang, Bingzhi; DeLuna, Frank; Sun, LuZhe; Ye, Jing Yong

2018-02-01

Breast cancer treatment options often include medications that target the overexpression of growth factor receptors, such as the proto-oncogene human epidermal growth factor receptor 2 (HER2/neu) and epidermal growth factor receptor (EGFR) to suppress the abnormal growth of cancerous cells and induce cancer regression. Although effective, certain treatments are toxic to vital organs, and demand assurance that the pursued receptor is present at the tumor before administration of the drug. This requires diagnostic tools to provide tumor molecular signatures, as well as locational information. In this study, we utilized a fiber-optic probe to characterize in vivo HER2 and EGFR overexpressed tumors through the fluorescence of targeted dyes. HER2 and EGFR antibodies were conjugated with ICG-Sulfo-OSu and Alexa Fluor 680, respectively, to tag BT474 (HER2+) and MDA-MB-468 (EGFR+) tumors. The fiber was inserted into the samples via a 30-gauge needle. Different wavelengths of a supercontinuum laser were selected to couple into the fiber and excite the corresponding fluorophores in the samples. The fluorescence from the dyes was collected through the same fiber and quantified by a time-correlated single photon counter. Fluorescence at different antibody-dye concentrations was measured for calibration. Mice with subcutaneous HER2+ and/or EGFR+ tumors received intravenous injections of the conjugates and were later probed at the tumor sites. The measured fluorescence was used to distinguish between tumor types and to calculate the concentration of the antibody-dye conjugates, which were detectable at levels as low as 40 nM. The fiber-optic probe presents a minimally invasive instrument to characterize the molecular signatures of breast cancer in vivo.

Fluorescence lifetime based bioassays

Science.gov (United States)

Meyer-Almes, Franz-Josef

2017-12-01

Fluorescence lifetime (FLT) is a robust intrinsic property and material constant of fluorescent matter. Measuring this important physical indicator has evolved from a laboratory curiosity to a powerful and established technique for a variety of applications in drug discovery, medical diagnostics and basic biological research. This distinct trend was mainly driven by improved and meanwhile affordable laser and detection instrumentation on the one hand, and the development of suitable FLT probes and biological assays on the other. In this process two essential working approaches emerged. The first one is primarily focused on high throughput applications employing biochemical in vitro assays with no requirement for high spatial resolution. The second even more dynamic trend is the significant expansion of assay methods combining highly time and spatially resolved fluorescence data by fluorescence lifetime imaging. The latter approach is currently pursued to enable not only the investigation of immortal tumor cell lines, but also specific tissues or even organs in living animals. This review tries to give an actual overview about the current status of FLT based bioassays and the wide range of application opportunities in biomedical and life science areas. In addition, future trends of FLT technologies will be discussed.

Fluorescence-enhanced optical imaging in large tissue volumes using a gain-modulated ICCD camera

International Nuclear Information System (INIS)

Godavarty, Anuradha; Eppstein, Margaret J; Zhang, Chaoyang; Theru, Sangeeta; Thompson, Alan B; Gurfinkel, Michael; Sevick-Muraca, Eva M

2003-01-01

A novel image-intensified charge-coupled device (ICCD) imaging system has been developed to perform 3D fluorescence tomographic imaging in the frequency-domain using near-infrared contrast agents. The imager is unique since it (i) employs a large tissue-mimicking phantom, which is shaped and sized to resemble a female breast and part of the extended chest-wall region, and (ii) enables rapid data acquisition in the frequency-domain by using a gain-modulated ICCD camera. Diffusion model predictions are compared to experimental measurements using two different referencing schemes under two different experimental conditions of perfect and imperfect uptake of fluorescent agent into a target. From these experimental measurements, three-dimensional images of fluorescent absorption were reconstructed using a computationally efficient variant of the approximate extended Kalman filter algorithm. The current work represents the first time that 3D fluorescence-enhanced optical tomographic reconstructions have been achieved from experimental measurements of the time-dependent light propagation on a clinically relevant breast-shaped tissue phantom using a gain-modulated ICCD camera

Fluorescence-based remote irradiation sensor in liquid-filled hollow-core photonic crystal fiber

Energy Technology Data Exchange (ETDEWEB)

Zeltner, R.; Russell, P. St.J. [Max Planck Institute for the Science of Light, Guenther-Scharowsky-Str. 1, 91058 Erlangen (Germany); Department of Physics, University of Erlangen-Nuremberg, Guenther-Scharowsky-Str. 1, 91058 Erlangen (Germany); Bykov, D. S.; Xie, S. [Max Planck Institute for the Science of Light, Guenther-Scharowsky-Str. 1, 91058 Erlangen (Germany); Euser, T. G. [Max Planck Institute for the Science of Light, Guenther-Scharowsky-Str. 1, 91058 Erlangen (Germany); Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom)

2016-06-06

We report an irradiation sensor based on a fluorescent “flying particle” that is optically trapped and propelled inside the core of a water-filled hollow-core photonic crystal fiber. When the moving particle passes through an irradiated region, its emitted fluorescence is captured by guided modes of the fiber core and so can be monitored using a filtered photodiode placed at the fiber end. The particle speed and position can be precisely monitored using in-fiber Doppler velocimetry, allowing the irradiation profile to be measured to a spatial resolution of ∼10 μm. The spectral response can be readily adjusted by appropriate choice of particle material. Using dye-doped polystyrene particles, we demonstrate detection of green (532 nm) and ultraviolet (340 nm) light.

A three-step reconstruction method for fluorescence molecular tomography based on compressive sensing

DEFF Research Database (Denmark)

Zhu, Yansong; Jha, Abhinav K.; Dreyer, Jakob K.

2017-01-01

Fluorescence molecular tomography (FMT) is a promising tool for real time in vivo quantification of neurotransmission (NT) as we pursue in our BRAIN initiative effort. However, the acquired image data are noisy and the reconstruction problem is ill-posed. Further, while spatial sparsity of the NT...... matrix coherence. The resultant image data are input to a homotopy-based reconstruction strategy that exploits sparsity via ℓ1 regularization. The reconstructed image is then input to a maximum-likelihood expectation maximization (MLEM) algorithm that retains the sparseness of the input estimate...... and improves upon the quantitation by accurate Poisson noise modeling. The proposed reconstruction method was evaluated in a three-dimensional simulated setup with fluorescent sources in a cuboidal scattering medium with optical properties simulating human brain cortex (reduced scattering coefficient: 9.2 cm-1...

340 nm pulsed UV LED system for europium-based time-resolved fluorescence detection of immunoassays

OpenAIRE

Rodenko, Olga; Fodgaard, Henrik; Tidemand-Lichtenberg, Peter; Petersen, Paul Michael; Pedersen, Christian

2016-01-01

We report on the design, development and investigation of an optical system based on UV light emitting diode (LED) excitation at 340 nm for time-resolved fluorescence detection of immunoassays. The system was tested to measure cardiac marker Troponin I with a concentration of 200 ng/L in immunoassay. The signal-to-noise ratio was comparable to state-of-the-art Xenon flash lamp based unit with equal excitation energy and without overdriving the LED. We performed a comparative study of the flas...

Fluorescence detection using optical waveguide collection device with high efficiency on assembly of nitrogen vacancy centers in diamond

Science.gov (United States)

Zhang, Shaowen; Ma, Zongmin; Qin, Li; Fu, Yueping; Shi, Yunbo; Liu, Jun; Li, Yan Jun

2018-01-01

In this letter, we propose a fluorescence waveguide excitation and collection (FWEC) method that allows for an excess of 45% collection efficiency of pump photons into optically detected magnetic resonance. The FWEC system used can collect fluorescence 96 times higher than the confocal system under spin manipulation with a microwave. Furthermore, the signal-to-noise ratio (SNR) of the FWEC system is improved 9 times compared with that of the confocal system. In addition, the increase in contrast observed using the FWEC system shows that the integration of the system is much improved with 3D printing technology. Thus, this research has a great potential application in subsequent magnetic detection and quantum optics.

Beveled fiber-optic probe couples a ball lens for improving depth-resolved fluorescence measurements of layered tissue: Monte Carlo simulations

International Nuclear Information System (INIS)

Jaillon, Franck; Zheng Wei; Huang Zhiwei

2008-01-01

In this study, we evaluate the feasibility of designing a beveled fiber-optic probe coupled with a ball lens for improving depth-resolved fluorescence measurements of epithelial tissue using Monte Carlo (MC) simulations. The results show that by using the probe configuration with a beveled tip collection fiber and a flat tip excitation fiber associated with a ball lens, discrimination of fluorescence signals generated in different tissue depths is achievable. In comparison with a flat-tip collection fiber, the use of a large bevel angled collection fiber enables a better differentiation between the shallow and deep tissue layers by changing the excitation-collection fiber separations. This work suggests that the beveled fiber-optic probe coupled with a ball lens has the potential to facilitate depth-resolved fluorescence measurements of epithelial tissues

A new optical method improves fluorescence guided diagnosis of bladder tumor in the outpatient department and reveals significant photo bleaching problems in established inpatients PDD techniques

Science.gov (United States)

Lindvold, Lars R.; Hermann, Gregers G.

2013-03-01

Photo dynamic diagnosis (PDD) is a convenient and well-documented procedure for diagnosis of bladder cancer and tumours using endoscopic techniques. At present, this procedure is available only for routine use in an operating room (OR) and often with substantial photobleaching effects of the photosensitizer. We present a novel optical design of the endoscopic PDD procedure that allows the procedure to be performed in the outpatient department (OPD) and not only in the OR. Thereby, inpatient procedures lasting 1-2 days may be replaced by a few hours lasting procedure in the OPD. Urine blurs the fluorescence during PDD used in the OPD. Urine contains fluorescent metabolites that are excited by blue light giving an opaque green fluorescence confounding the desired red fluorescence (PDD) from the tumour tissue. Measurements from the clinical situation has shown that some systems for PPD based on blue light illumination (PDD mode) and white light illumination used for bladder tumour diagnosis and surgery suffers some inherent disadvantages, i.e., photo bleaching in white light that impairs the possibility for PDD as white light usually is used before the blue light for PDD. Based on spectroscopic observations of urine and the photoactive dye Protoporphyrin IX used in PDD a novel optical system for use with the cystoscope has been devised that solves the problem of green fluorescence from urine. This and the knowledge of photo-bleaching pitfalls in established systems make it possible to perform PDD of bladder tumours in the OPD and to improve PDD in the OR.

Trapping, manipulation and rapid rotation of NBD-C8 fluorescent single microcrystals in optical tweezers

International Nuclear Information System (INIS)

GALAUP, Jean-Pierre; RODRIGUEZ-OTAZO, Mariela; AUGIER-CALDERIN, Angel; LAMERE; Jean-Francois; FERY-FORGUES, Suzanne

2009-01-01

We have built an optical tweezers experiment based on an inverted microscope to trap and manipulate single crystals of micro or sub-micrometer size made from fluorescent molecules of 4-octylamino-7-nitrobenzoxadiazole (NBD-C8). These single crystals have parallelepiped shapes and exhibit birefringence properties evidenced through optical experiments between crossed polarizers in a polarizing microscope. The crystals are uniaxial with their optical axis oriented along their largest dimension. Trapped in the optical trap, the organic micro-crystals are oriented in such a way that their long axis is along the direction of the beam propagation, and their short axis follows the direction of the linear polarization. Therefore, with linearly polarized light, simply rotating the light polarization can orient the crystal. When using circularly or only elliptically polarized light, the crystal can spontaneously rotate and reach rotation speed of several hundreds of turns per second. A surprising result has been observed: when the incident power is growing up, the rotation speed increases to reach a maximum value and then decreases even when the power is still growing up. Moreover, this evolution is irreversible. Different possible explanations can be considered. The development of a 3D control of the crystals by dynamical holography using liquid crystal spatial modulators will be presented and discussed on the basis of the most recent results obtained. (Author)

Light sheet-based fluorescence microscopy (LSFM) reduces phototoxic effects and provides new means for the modern life sciences

Science.gov (United States)

Pampaloni, Francesco; Ansari, Nari; Girard, Philippe; Stelzer, Ernst H. K.

2011-07-01

Most optical technologies are applied to flat, basically two-dimensional cellular systems. However, physiological meaningful information relies on the morphology, the mechanical properties and the biochemistry of a cell's context. A cell requires the complex three-dimensional relationship to other cells. However, the observation of multi-cellular biological specimens remains a challenge. Specimens scatter and absorb light, thus, the delivery of the probing light and the collection of the signal light become inefficient; many endogenous biochemical compounds also absorb light and suffer degradation of some sort (photo-toxicity), which induces malfunction of a specimen. In conventional and confocal fluorescence microscopy, whenever a single plane, the entire specimen is illuminated. Recording stacks of images along the optical Z-axis thus illuminates the entire specimen once for each plane. Hence, cells are illuminated 10-20 and fish 100-300 times more often than they are observed. This can be avoided by changing the optical arrangement. The basic idea is to use light sheets, which are fed into the specimen from the side and overlap with the focal plane of a wide-field fluorescence microscope. In contrast to an epi-fluorescence arrangement, such an azimuthal fluorescence arrangement uses two independently operated lenses for illumination and detection. Optical sectioning and no photo-toxic damage or photo-bleaching outside a small volume close to the focal plane are intrinsic properties. Light sheet-based fluorescence microscopy (LSFM) takes advantage of modern camera technologies. LSFM can be operated with laser cutters and for fluorescence correlation spectroscopy. During the last few years, LSFM was used to record zebrafish development from the early 32-cell stage until late neurulation with sub-cellular resolution and short sampling periods (60-90 sec/stack). The recording speed was five 4-Megapixel large frames/sec with a dynamic range of 12-14 bit. We followed

SERS and fluorescence-based ultrasensitive detection of mercury in water.

Science.gov (United States)

Makam, Pandeeswar; Shilpa, Rohilla; Kandjani, Ahmad Esmaielzadeh; Periasamy, Selvakannan R; Sabri, Ylias Mohammad; Madhu, Chilakapati; Bhargava, Suresh Kumar; Govindaraju, Thimmaiah

2018-02-15

The development of reliable and ultrasensitive detection marker for mercury ions (Hg 2+ ) in drinking water is of great interest for toxicology assessment, environmental protection and human health. Although many Hg 2+ detection methods have been developed, only few offer sensitivities below 1pM. Herein, we describe a simple histidine (H) conjugated perylene diimide (PDI) bolaamphiphile (HPH) as a dual-responsive optical marker to develop highly selective and sensitive probe as visible (sol-to-gel transformation), fluorescence and SERS-based Hg 2+ sensor platform in the water. Remarkably, HPH as a SERS marker supported on Au deposited monodispersed nanospheres monolayers (Au-MNM) of polystyrene offers an unprecedented selectivity and the best ever reported detection limit (LOD) of 60 attomolar (aM, 0.01 parts-per-quadrillion (ppq)) for Hg 2+ in water. This is ten orders of magnitude lower than the United States Environmental Protection Agency (USEPA) tolerance limit of Hg 2+ in drinking water (10nM, 2 ppb). This simple and effective design principle of host-guest interactions driven fluorescence and SERS-based detection may inspire the future molecular engineering strategies for the development of ultrasensitive toxic analyte sensor platforms. Copyright © 2017 Elsevier B.V. All rights reserved.

X-ray optics for scanning fluorescence microscopy and other applications

International Nuclear Information System (INIS)

Ryon, R.W.; Warburton, W.K.

1992-05-01

Scanning x-ray fluorescence microscopy is analogous to scanning electron microscopy. Maps of chemical element distribution are produced by scanning with a very small x-ray beam. Goal is to perform such scanning microscopy with resolution in the range of <1 to 10 μm, using standard laboratory x-ray tubes. We are investigating mirror optics in the Kirkpatrick-Baez (K-B) configuration. K-B optics uses two curved mirrors mounted orthogonally along the optical axis. The first mirror provides vertical focus, the second mirror provides horizontal focus. We have used two types of mirrors: synthetic multilayers and crystals. Multilayer mirrors are used with lower energy radiation such as Cu Kα. At higher energies such as Ag Kα, silicon wafers are used in order to increase the incidence angles and thereby the photon collection efficiency. In order to increase the surface area of multilayers which reflects x-rays at the Bragg angle, we have designed mirrors with the spacing between layers graded along the optic axis in order to compensate for the changing angle of incidence. Likewise, to achieve a large reflecting surface with silicon, the wafers are placed on a specially designed lever arm which is bent into a log spiral by applying force at one end. In this way, the same diffracting angle is maintained over the entire surface of the wafer, providing a large solid angle for photon collection

An all-fiber partial discharge monitoring system based on both intrinsic fiber optic interferometry sensor and fluorescent fiber

Science.gov (United States)

Yin, Zelin; Zhang, Ruirui; Tong, Jie; Chen, Xi

2013-12-01

Partial discharges (PDs) are an electrical phenomenon that occurs within a transformer whenever the voltage stress is sufficient to produce ionization in voids or inclusions within a solid dielectric, at conductor/dielectric interfaces, or in bubbles within liquid dielectrics such as oil; high-frequency transient current discharges will then appear repeatedly and will progressively deteriorate the insulation, ultimately leading to breakdown. Fiber sensor has great potential on the partial discharge detection in high-voltage equipment for its immunity to electromagnetic interference and it can take direct measurement in the high voltage equipment. The energy released in PDs produces a number of effects, resulting in flash, chemical and structural changes and electromagnetic emissions and so on. Acoustic PD detection is based on the mechanical pressure wave emitted from the discharge and fluorescent fiber PD detection is based on the emitted light produced by ionization, excitation and recombination processes during the discharge. Both of the two methods have the shortage of weak anti-interference capacity in the physical environment, like thunder or other sound source. In order to avoid the false report, an all-fiber combined PD detection system of the two methods is developed in this paper. In the system the fluorescent fiber PD sensor is considered as a reference signal, three F-P based PD detection sensors are used to both monitor the PD intensity and calculate the exact position of the discharge source. Considering the wave band of the F-P cavity and the fluorescent probe are quite different, the reflection spectrum of the F-P cavity is in the infrared region, however the fluorescent probe is about 600nm to 700nm, thus the F-P sensor and fluorescent fiber probe can be connected in one fiber and the reflection light can be detected by two different detectors without mutual interference. The all-fiber partial discharge monitoring system not only can detect the PDs

Integrated Photoacoustic and Fluorescence Confocal Microscopy

OpenAIRE

Wang, Yu; Maslov, Konstantin; Kim, Chulhong; Hu, Song; Wang, Lihong V.

2010-01-01

We have developed a dual-modality imaging system by integrating optical-resolution photoacoustic microscopy and fluorescence confocal microscopy to provide optical absorption and fluorescence contrasts simultaneously. By sharing the same laser source and objective lens, intrinsically registered photoacoustic and fluorescence images are acquired in a single scan. The micrometer resolution allows imaging of both blood and lymphatic vessels down to the capillary level. Simultaneous photoacoustic...

Photoluminescence properties of Bi/Al-codoped silica optical fiber based on atomic layer deposition method

International Nuclear Information System (INIS)

Wen, Jianxiang; Wang, Jie; Dong, Yanhua; Chen, Na; Luo, Yanhua; Peng, Gang-ding; Pang, Fufei; Chen, Zhenyi; Wang, Tingyun

2015-01-01

Highlights: • We report on a new fabrication method of producing Bi/Al-codoped silica optical fibers. • There are obvious Bi-type ions absorption peaks at 520, 700 and 800 nm. • The fluorescence peaks are 1130 and 1145 nm with 489 and 705 nm excitations, respectively. • Their fluorescence lifetimes are 701 and 721 μs, respectively. • And then there are obvious fluorescence bands in 600–850 and 900–1650 nm with 532 nm pump exciting. • There is a maximum fluorescence intensity peak at 1120 nm, and its full wave at half maximum (FWHM) is approximately 180 nm. • These may mainly result from the interaction between Bi and Al ions. • The Bi/Al-codoped silica optical fibers would be used in high power or broadly tunable laser sources, and optical fiber amplifier in the optical communication fields. - Abstract: The Bi/Al-codoped silica optical fibers are fabricated by atomic layer deposition (ALD) doping technique combing with conventional modified chemical vapor deposition (MCVD) process. Bi 2 O 3 and Al 2 O 3 are induced into silica optical fiber core layer by ALD technique, with Bis (2,2,6,6-tetra-methyl-3,5-heptanedionato) Bismuth(III) (Bi(thd) 3 ) and H 2 O as Bi and O precursors, and with Al(CH 3 ) 3 (TMA) as Al precursor, respectively. The structure features and optical properties of Bi/Al-codoped silica optical fibers are investigated. Bi 2 O 3 stoichiometry is confirmed by X-ray photoelectron spectroscopy (XPS). The valence state of Bi element is +3. Concentration distribution of Si, Ge and O elements is approximately 24–33, 9 and 66 mol%, respectively, in fiber preform core and cladding layer region. Bi and Al ions have been also slightly doped approximately 150–180 and 350–750 ppm in fiber preform core, respectively. Refractive index difference of the Bi/Al-codoped fiber is approximately 0.58% using optical fiber refractive index profiler analyzer. There are obvious Bi-type ions absorption peaks at 520, 700 and 800 nm. The fluorescence

Photoluminescence properties of Bi/Al-codoped silica optical fiber based on atomic layer deposition method

Energy Technology Data Exchange (ETDEWEB)

Wen, Jianxiang, E-mail: wenjx@shu.edu.cn [Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072 (China); Wang, Jie; Dong, Yanhua; Chen, Na [Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072 (China); Luo, Yanhua; Peng, Gang-ding [Photonics & Optical Communications, School of Electrical Engineering & Telecommunications, University of New South Wales, Sydney 2052, NSW (Australia); Pang, Fufei; Chen, Zhenyi [Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072 (China); Wang, Tingyun, E-mail: tywang@mail.shu.edu.cn [Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200072 (China)

2015-09-15

Highlights: • We report on a new fabrication method of producing Bi/Al-codoped silica optical fibers. • There are obvious Bi-type ions absorption peaks at 520, 700 and 800 nm. • The fluorescence peaks are 1130 and 1145 nm with 489 and 705 nm excitations, respectively. • Their fluorescence lifetimes are 701 and 721 μs, respectively. • And then there are obvious fluorescence bands in 600–850 and 900–1650 nm with 532 nm pump exciting. • There is a maximum fluorescence intensity peak at 1120 nm, and its full wave at half maximum (FWHM) is approximately 180 nm. • These may mainly result from the interaction between Bi and Al ions. • The Bi/Al-codoped silica optical fibers would be used in high power or broadly tunable laser sources, and optical fiber amplifier in the optical communication fields. - Abstract: The Bi/Al-codoped silica optical fibers are fabricated by atomic layer deposition (ALD) doping technique combing with conventional modified chemical vapor deposition (MCVD) process. Bi{sub 2}O{sub 3} and Al{sub 2}O{sub 3} are induced into silica optical fiber core layer by ALD technique, with Bis (2,2,6,6-tetra-methyl-3,5-heptanedionato) Bismuth(III) (Bi(thd){sub 3}) and H{sub 2}O as Bi and O precursors, and with Al(CH{sub 3}){sub 3} (TMA) as Al precursor, respectively. The structure features and optical properties of Bi/Al-codoped silica optical fibers are investigated. Bi{sub 2}O{sub 3} stoichiometry is confirmed by X-ray photoelectron spectroscopy (XPS). The valence state of Bi element is +3. Concentration distribution of Si, Ge and O elements is approximately 24–33, 9 and 66 mol%, respectively, in fiber preform core and cladding layer region. Bi and Al ions have been also slightly doped approximately 150–180 and 350–750 ppm in fiber preform core, respectively. Refractive index difference of the Bi/Al-codoped fiber is approximately 0.58% using optical fiber refractive index profiler analyzer. There are obvious Bi-type ions absorption

Combined optic system based on polycapillary X-ray optics and single-bounce monocapillary optics for focusing X-rays from a conventional laboratory X-ray source

Energy Technology Data Exchange (ETDEWEB)

Sun, Xuepeng; Liu, Zhiguo [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Sun, Tianxi, E-mail: stx@bnu.edu.cn [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Yi, Longtao; Sun, Weiyuan; Li, Fangzuo; Jiang, Bowen [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China); Ma, Yongzhong [Center for Disease Control and Prevention of Beijing, Beijing 100013 (China); Ding, Xunliang [The Key Laboratory of Beam Technology and Materials Modification of the Ministry of Education, Beijing Normal University, Beijing 100875 (China); College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

2015-12-01

Two combined optic systems based on polycapillary X-ray optics and single-bounce monocapillary optics (SBMO) were designed for focusing the X-rays from a conventional laboratory X-ray source. One was based on a polycapillary focusing X-ray lens (PFXRL) and a single-bounce ellipsoidal capillary (SBEC), in which the output focal spot with the size of tens of micrometers of the PFXRL was used as the “virtual” X-ray source for the SBEC. The other system was based on a polycapillary parallel X-ray lens (PPXRL) and a single-bounce parabolic capillary (SBPC), in which the PPXRL transformed the divergent X-ray beam from an X-ray source into a quasi-parallel X-ray beam with the divergence of sever milliradians as the incident illumination of the SBPC. The experiment results showed that the combined optic systems based on PFXRL and SBEC with a Mo rotating anode X-ray generator with the focal spot with a diameter of 300 μm could obtain a focal spot with the total gain of 14,300 and focal spot size of 37.4 μm, and the combined optic systems based on PPXRL and SBPC with the same X-ray source mentioned above could acquire a focal spot with the total gain of 580 and focal spot size of 58.3 μm, respectively. The two combined optic systems have potential applications in micro X-ray diffraction, micro X-ray fluorescence, micro X-ray absorption near edge structure, full field X-ray microscopes and so on.

Fluorescence Endoscopy in vivo based on Fiber-bundle Measurements

Energy Technology Data Exchange (ETDEWEB)

Zufiria, B.; Gomez-Garcia, P.; Stamatakis, K.; Vaquero, J.J.; Fresno, M.; Desco, M.; Ripoll, J.; Arranz, A.

2016-07-01

High-resolution imaging techniques have become important for the determination of the cellular organization that is coupled to organ function. In many cases the organ can be viewed without the need of ionizing radiation techniques in an easier way. This is the case of the gastrointestinal tract, an organ that can be directly accessed with endoscopy avoiding any invasive procedure. Here we describe the design, assembly and testing of a fluorescence high-resolution endoscope intended for the study of the cellular organization of the colon in an experimental mouse model of colon carcinoma. Access to the colon of the mouse took place using a fiber-optic bundle that redirects the light coming from a LED to produce fluorescence and detect it back through the fiber bundle. Results from in vivo and ex-vivo test using our fluorescence fiber bundle endoscope show altered tissue structure and destruction of the intestinal crypts in tumor-bearing areas compared with healthy tissue. (Author)

Direct comparison of soft x-ray images of organelles with optical fluorescence images

International Nuclear Information System (INIS)

Ishino, Masahiko; Kado, Masataka; Kishimoto, Maki; Nishikino, Masaharu; Ohba, Toshiyuki; Kaihori, Takeshi; Kawachi, Tetsuya; Tamotsu, Satoshi; Yasuda, Keiko; Mikata, Yuji; Shinohara, Kunio

2011-01-01

Soft x-ray microscopes operating in the water window region are capable of imaging living hydrated cells. Up to now, we have been able to take some soft x-ray images of living cells by the use of a contact x-ray microscope system with laser produced plasma soft x-ray source. Since the soft x-ray images are different from the optical images obtained with an ordinary microscope, it is very important to identify what is seen in the x-ray images. Hence, we have demonstrated the direct comparison between the images of organelles obtained with a fluorescence microscope and those with a soft x-ray microscope. Comparing the soft x-ray images to the fluorescence images, the fine structures of the organelles could be identified and observed. (author)

Rapid and prodium iodide-compatible optical clearing method for brain tissue based on sugar/sugar-alcohol

Science.gov (United States)

Yu, Tingting; Qi, Yisong; Wang, Jianru; Feng, Wei; Xu, Jianyi; Zhu, Jingtan; Yao, Yingtao; Gong, Hui; Luo, Qingming; Zhu, Dan

2016-08-01

The developed optical clearing methods show great potential for imaging of large-volume tissues, but these methods present some nonnegligible limitations such as complexity of implementation and long incubation times. In this study, we tried to screen out rapid optical clearing agents by means of molecular dynamical simulation and experimental demonstration. According to the optical clearing potential of sugar and sugar-alcohol, we further evaluated the improvement in the optical clearing efficacy of mouse brain samples, imaging depth, fluorescence preservation, and linear deformation. The results showed that drops of sorbitol, sucrose, and fructose could quickly make the mouse brain sample transparent within 1 to 2 min, and induce about threefold enhancement in imaging depth. The former two could evidently enhance the fluorescence intensity of green fluorescent protein (GFP) and prodium iodide (PI) nuclear dye. Fructose could significantly increase the fluorescence intensity of PI, but slightly decrease the fluorescence intensity of GFP. Even though the three agents caused some shrinkage in samples, the contraction in horizontal and longitudinal directions are almost the same.

Image navigation as a means to expand the boundaries of fluorescence-guided surgery.

Science.gov (United States)

Brouwer, Oscar R; Buckle, Tessa; Bunschoten, Anton; Kuil, Joeri; Vahrmeijer, Alexander L; Wendler, Thomas; Valdés-Olmos, Renato A; van der Poel, Henk G; van Leeuwen, Fijs W B

2012-05-21

Hybrid tracers that are both radioactive and fluorescent help extend the use of fluorescence-guided surgery to deeper structures. Such hybrid tracers facilitate preoperative surgical planning using (3D) scintigraphic images and enable synchronous intraoperative radio- and fluorescence guidance. Nevertheless, we previously found that improved orientation during laparoscopic surgery remains desirable. Here we illustrate how intraoperative navigation based on optical tracking of a fluorescence endoscope may help further improve the accuracy of hybrid surgical guidance. After feeding SPECT/CT images with an optical fiducial as a reference target to the navigation system, optical tracking could be used to position the tip of the fluorescence endoscope relative to the preoperative 3D imaging data. This hybrid navigation approach allowed us to accurately identify marker seeds in a phantom setup. The multispectral nature of the fluorescence endoscope enabled stepwise visualization of the two clinically approved fluorescent dyes, fluorescein and indocyanine green. In addition, the approach was used to navigate toward the prostate in a patient undergoing robot-assisted prostatectomy. Navigation of the tracked fluorescence endoscope toward the target identified on SPECT/CT resulted in real-time gradual visualization of the fluorescent signal in the prostate, thus providing an intraoperative confirmation of the navigation accuracy.

Pathological diagnosis of bladder cancer by image analysis of hypericin induced fluorescence cystoscopic images

Science.gov (United States)

Kah, James C. Y.; Olivo, Malini C.; Lau, Weber K. O.; Sheppard, Colin J. R.

2005-08-01

Photodynamic diagnosis of bladder carcinoma based on hypericin fluorescence cystoscopy has shown to have a higher degree of sensitivity for the detection of flat bladder carcinoma compared to white light cystoscopy. The potential of the photosensitizer hypericin-induced fluorescence in performing non-invasive optical biopsy to grade bladder cancer in vivo using fluorescence cystoscopic image analysis without surgical resection for tissue biopsy is investigated in this study. The correlation between tissue fluorescence and histopathology of diseased tissue was explored and a diagnostic algorithm based on fluorescence image analysis was developed to classify the bladder cancer without surgical resection for tissue biopsy. Preliminary results suggest a correlation between tissue fluorescence and bladder cancer grade. By combining both the red-to-blue and red-to-green intensity ratios into a 2D scatter plot yields an average sensitivity and specificity of around 70% and 85% respectively for pathological cancer grading of the three different grades of bladder cancer. Therefore, the diagnostic algorithm based on colorimetric intensity ratio analysis of hypericin fluorescence cystoscopic images developed in this preliminary study shows promising potential to optically diagnose and grade bladder cancer in vivo.

Efficient Fluorescence Resonance Energy Transfer between Quantum Dots and Gold Nanoparticles Based on Porous Silicon Photonic Crystal for DNA Detection.

Science.gov (United States)

Zhang, Hongyan; Lv, Jie; Jia, Zhenhong

2017-05-10

A novel assembled biosensor was prepared for detecting 16S rRNA, a small-size persistent specific for Actinobacteria. The mechanism of the porous silicon (PS) photonic crystal biosensor is based on the fluorescence resonance energy transfer (FRET) between quantum dots (QDs) and gold nanoparticles (AuNPs) through DNA hybridization, where QDs act as an emission donor and AuNPs serve as a fluorescence quencher. Results showed that the photoluminescence (PL) intensity of PS photonic crystal was drastically increased when the QDs-conjugated probe DNA was adhered to the PS layer by surface modification using a standard cross-link chemistry method. The PL intensity of QDs was decreased when the addition of AuNPs-conjugated complementary 16S rRNA was dropped onto QDs-conjugated PS. Based on the analysis of different target DNA concentration, it was found that the decrease of the PL intensity showed a good linear relationship with complementary DNA concentration in a range from 0.25 to 10 μM, and the detection limit was 328.7 nM. Such an optical FRET biosensor functions on PS-based photonic crystal for DNA detection that differs from the traditional FRET, which is used only in liquid. This method will benefit the development of a new optical FRET label-free biosensor on Si substrate and has great potential in biochips based on integrated optical devices.

Time-resolved fluorescence spectroscopy

International Nuclear Information System (INIS)

Gustavsson, Thomas; Mialocq, Jean-Claude

2007-01-01

This article addresses the evolution in time of light emitted by a molecular system after a brief photo-excitation. The authors first describe fluorescence from a photo-physical point of view and discuss the characterization of the excited state. Then, they explain some basic notions related to fluorescence characterization (lifetime and decays, quantum efficiency, so on). They present the different experimental methods and techniques currently used to study time-resolved fluorescence. They discuss basic notions of time resolution and spectral reconstruction. They briefly present some conventional methods: intensified Ccd cameras, photo-multipliers and photodiodes associated with a fast oscilloscope, and phase modulation. Other methods and techniques are more precisely presented: time-correlated single photon counting (principle, examples, and fluorescence lifetime imagery), streak camera (principle, examples), and optical methods like the Kerr optical effect (principle and examples) and fluorescence up-conversion (principle and theoretical considerations, examples of application)

Recent developments in multimodality fluorescence imaging probes

Directory of Open Access Journals (Sweden)

Jianhong Zhao

2018-05-01

Full Text Available Multimodality optical imaging probes have emerged as powerful tools that improve detection sensitivity and accuracy, important in disease diagnosis and treatment. In this review, we focus on recent developments of optical fluorescence imaging (OFI probe integration with other imaging modalities such as X-ray computed tomography (CT, magnetic resonance imaging (MRI, positron emission tomography (PET, single-photon emission computed tomography (SPECT, and photoacoustic imaging (PAI. The imaging technologies are briefly described in order to introduce the strengths and limitations of each techniques and the need for further multimodality optical imaging probe development. The emphasis of this account is placed on how design strategies are currently implemented to afford physicochemically and biologically compatible multimodality optical fluorescence imaging probes. We also present studies that overcame intrinsic disadvantages of each imaging technique by multimodality approach with improved detection sensitivity and accuracy. KEY WORDS: Optical imaging, Fluorescence, Multimodality, Near-infrared fluorescence, Nanoprobe, Computed tomography, Magnetic resonance imaging, Positron emission tomography, Single-photon emission computed tomography, Photoacoustic imaging

[A cell-based detection of ciguatoxin using sodium fluorescence probe].

Science.gov (United States)

Yuan, Jian-hui; Yang, Hui; Tang, Huan-wen; Huang, Wei; Xu, Xin-yun; Liu, Jian-jun; Ke, Yue-bin; Cheng, Jin-quan; Zhuang, Zhi-xiong

2011-04-01

To establish a cell-based detection method of ciguatoxin using fluorescence assay. Mouse neuroblastoma N-2A cells were exposed to ouabain and veratridine and different concentrations of standard ciguatoxin samples (P-CTX-1) to establish the curvilinear relationship between the toxin dosage and fluorescence intensity using the sodium fluorescence probe CoroNaTM Green. The toxicity curvilinear relationship was also generated between the toxin dosage and cell survival using CCK-8 method. Based on these standard curves, the presence of ciguatoxin was detected in 33 samples of deep-sea coral fish. A correlation was found between the detection results of cell-based fluorescence assay and cytotoxicity assay, whose detection limit reached 103 g/ml and 1012 g/ml, respectively. The cell-based fluorescent assay sensitivity showed a higher sensitivity than cytotoxicity assay with a 2-4 h reduction of the detection time. The cell-based fluorescent assay can quickly and sensitively detect ciguatoxin and may serve as a good option for preliminary screening of the toxin.

Adaptive-optics SLO imaging combined with widefield OCT and SLO enables precise 3D localization of fluorescent cells in the mouse retina.

Science.gov (United States)

Zawadzki, Robert J; Zhang, Pengfei; Zam, Azhar; Miller, Eric B; Goswami, Mayank; Wang, Xinlei; Jonnal, Ravi S; Lee, Sang-Hyuck; Kim, Dae Yu; Flannery, John G; Werner, John S; Burns, Marie E; Pugh, Edward N

2015-06-01

Adaptive optics scanning laser ophthalmoscopy (AO-SLO) has recently been used to achieve exquisite subcellular resolution imaging of the mouse retina. Wavefront sensing-based AO typically restricts the field of view to a few degrees of visual angle. As a consequence the relationship between AO-SLO data and larger scale retinal structures and cellular patterns can be difficult to assess. The retinal vasculature affords a large-scale 3D map on which cells and structures can be located during in vivo imaging. Phase-variance OCT (pv-OCT) can efficiently image the vasculature with near-infrared light in a label-free manner, allowing 3D vascular reconstruction with high precision. We combined widefield pv-OCT and SLO imaging with AO-SLO reflection and fluorescence imaging to localize two types of fluorescent cells within the retinal layers: GFP-expressing microglia, the resident macrophages of the retina, and GFP-expressing cone photoreceptor cells. We describe in detail a reflective afocal AO-SLO retinal imaging system designed for high resolution retinal imaging in mice. The optical performance of this instrument is compared to other state-of-the-art AO-based mouse retinal imaging systems. The spatial and temporal resolution of the new AO instrumentation was characterized with angiography of retinal capillaries, including blood-flow velocity analysis. Depth-resolved AO-SLO fluorescent images of microglia and cone photoreceptors are visualized in parallel with 469 nm and 663 nm reflectance images of the microvasculature and other structures. Additional applications of the new instrumentation are discussed.

High-fidelity optical reporting of neuronal electrical activity with an ultrafast fluorescent voltage sensor

Science.gov (United States)

St-Pierre, François; Marshall, Jesse D; Yang, Ying; Gong, Yiyang; Schnitzer, Mark J; Lin, Michael Z

2015-01-01

Accurate optical reporting of electrical activity in genetically defined neuronal populations is a long-standing goal in neuroscience. Here we describe Accelerated Sensor of Action Potentials 1 (ASAP1), a novel voltage sensor design in which a circularly permuted green fluorescent protein is inserted within an extracellular loop of a voltage-sensing domain, rendering fluorescence responsive to membrane potential. ASAP1 demonstrates on- and off- kinetics of 2.1 and 2.0 ms, reliably detects single action potentials and subthreshold potential changes, and tracks trains of action potential waveforms up to 200 Hz in single trials. With a favorable combination of brightness, dynamic range, and speed, ASAP1 enables continuous monitoring of membrane potential in neurons at KHz frame rates using standard epifluorescence microscopy. PMID:24755780

Isometric multimodal photoacoustic microscopy based on optically transparent micro-ring ultrasonic detection.

Science.gov (United States)

Dong, Biqin; Li, Hao; Zhang, Zhen; Zhang, Kevin; Chen, Siyu; Sun, Cheng; Zhang, Hao F

2015-01-01

Photoacoustic microscopy (PAM) is an attractive imaging tool complementary to established optical microscopic modalities by providing additional molecular specificities through imaging optical absorption contrast. While the development of optical resolution photoacoustic microscopy (ORPAM) offers high lateral resolution, the acoustically-determined axial resolution is limited due to the constraint in ultrasonic detection bandwidth. ORPAM with isometric spatial resolution along both axial and lateral direction is yet to be developed. Although recently developed sophisticated optical illumination and reconstruction methods offer improved axial resolution in ORPAM, the image acquisition procedures are rather complicated, limiting their capabilities for high-speed imaging and being easily integrated with established optical microscopic modalities. Here we report an isometric ORPAM based on an optically transparent micro-ring resonator ultrasonic detector and a commercial inverted microscope platform. Owing to the superior spatial resolution and the ease of integrating our ORPAM with established microscopic modalities, single cell imaging with extrinsic fluorescence staining, intrinsic autofluorescence, and optical absorption can be achieved simultaneously. This technique holds promise to greatly improve the accessibility of PAM to the broader biomedical researchers.

Fluorescent and Colorimetric Electrospun Nanofibers for Heavy-Metal Sensing

Directory of Open Access Journals (Sweden)

Idelma A. A. Terra

2017-12-01

Full Text Available The accumulation of heavy metals in the human body and/or in the environment can be highly deleterious for mankind, and currently, considerable efforts have been made to develop reliable and sensitive techniques for their detection. Among the detection methods, chemical sensors appear as a promising technology, with emphasis on systems employing optically active nanofibers. Such nanofibers can be obtained by the electrospinning technique, and further functionalized with optically active chromophores such as dyes, conjugated polymers, carbon-based nanomaterials and nanoparticles, in order to produce fluorescent and colorimetric nanofibers. In this review we survey recent investigations reporting the use of optically active electrospun nanofibers in sensors aiming at the specific detection of heavy metals using colorimetry and fluorescence methods. The examples given in this review article provide sufficient evidence of the potential of optically electrospun nanofibers as a valid approach to fabricate highly selective and sensitive optical sensors for fast and low-cost detection of heavy metals.

Hanle Detection for Optical Clocks

Directory of Open Access Journals (Sweden)

Xiaogang Zhang

2015-01-01

Full Text Available Considering the strong inhomogeneous spatial polarization and intensity distribution of spontaneous decay fluorescence due to the Hanle effect, we propose and demonstrate a universe Hanle detection configuration of electron-shelving method for optical clocks. Experimental results from Ca atomic beam optical frequency standard with electron-shelving method show that a designed Hanle detection geometry with optimized magnetic field direction, detection laser beam propagation and polarization direction, and detector position can improve the fluorescence collection rate by more than one order of magnitude comparing with that of inefficient geometry. With the fixed 423 nm fluorescence, the improved 657 nm optical frequency standard signal intensity is presented. The potential application of the Hanle detection geometry designed for facilitating the fluorescence collection for optical lattice clock with a limited solid angle of the fluorescence collection has been discussed. The Hanle detection geometry is also effective for ion detection in ion optical clock and quantum information experiments. Besides, a cylinder fluorescence collection structure is designed to increase the solid angle of the fluorescence collection in Ca atomic beam optical frequency standard.

Fluorescent silica colloids for study and visualization of skin care products.

Science.gov (United States)

Iyer, Swaminathan; Kievsky, Yaroslav; Sokolov, Igor

2007-08-01

The efficacy of skin care products depends on the time and dynamics of their absorbance by the skin, and its spatial distribution on the skin. Regular scrape-based methods may depend on the operator and are destructive and invasive in nature. Here, we describe a novel method based on non-contact optical measurements to trace the location and dynamics of skin care products on the skin. We use fluorescent silica colloidal particles of micron sizes at a rather small concentration as non-invasive tracers. As an example of skin care products, we use two base materials: either glycerin or vaseline. A mixture of each product with fluorescent particles is applied on human skin. The amount of fluorescence is monitored by means of a fluorescent spectrometer. The scraping method is used to compare with the spectroscopic measurements. Fluorescent tracers make the skin care product visible under UV light. This allows obtaining an optical image of the spatial distribution of the product on the skin. The quantitative data of fluorescence are well correlated with the scrape data. Comparison of the difference in the spectral and scraped mass data reveals the details of accumulation of the skin products in skin cracks and crevices. We described an efficient non-invasive benign method to quantify dynamics and to perform mapping of emollients and humectants on the skin.

An overview of remote sensing of chlorophyll fluorescence

Science.gov (United States)

Xing, Xiao-Gang; Zhao, Dong-Zhi; Liu, Yu-Guang; Yang, Jian-Hong; Xiu, Peng; Wang, Lin

2007-03-01

Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyl l - a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.

An optical method for reducing green fluorescence from urine during fluorescence-guided cystoscopy

Science.gov (United States)

Lindvold, Lars R.; Hermann, Gregers G.

2016-12-01

Photodynamic diagnosis (PDD) of bladder tumour tissue significantly improves endoscopic diagnosis and treatment of bladder cancer in rigid cystoscopes in the operating theatre and thus reduces tumour recurrence. PDD comprises the use of blue light, which unfortunately excites green fluorescence from urine. As this green fluorescence confounds the desired red fluorescence of the PDD, methods for avoiding this situation particularly in cystoscopy using flexible cystoscopes are desirable. In this paper we demonstrate how a tailor made high power LED light source at 525 nm can be used for fluorescence assisted tumour detection using both a flexible and rigid cystoscope used in the outpatient department (OPD) and operating room (OR) respectively. It is demonstrated both in vitro and in vivo how this light source can significantly reduce the green fluorescence problem with urine. At the same time this light source also is useful for exciting autofluorescence in healthy bladder mucosa. This autofluorescence then provides a contrast to the sensitized fluorescence (PDD) of tumours in the bladder.

Nanogap embedded silver gratings for surface plasmon enhanced fluorescence

Science.gov (United States)

Bhatnagar, Kunal

Plasmonic nanostructures have been extensively used in the past few decades for applications in sub-wavelength optics, data storage, optoelectronic circuits, microscopy and bio-photonics. The enhanced electromagnetic field produced at the metal and dielectric interface by the excitation of surface plasmons via incident radiation can be used for signal enhancement in fluorescence and surface enhanced Raman scattering studies. Novel plasmonic structures have shown to provide very efficient and extreme light concentration at the nano-scale in recent years. The enhanced electric field produced within a few hundred nanometers of these surfaces can be used to excite fluorophores in the surrounding environment. Fluorescence based bio-detection and bio-imaging are two of the most important tools in the life sciences and improving the qualities and capabilities of fluorescence based detectors and imaging equipment remains a big challenge for industry manufacturers. We report a novel fabrication technique for producing nano-gap embedded periodic grating substrates on the nanoscale using a store bought HD-DVD and conventional soft lithography procedures. Polymethylsilsesquioxane (PMSSQ) polymer is used as the ink for the micro-contact printing process with PDMS stamps obtained from the inexpensive HD-DVDs as master molds. Fluorescence enhancement factors of up to 118 times were observed with these silver nanostructures in conjugation with Rhodamine-590 fluorescent dye. These substrates are ideal candidates for a robust and inexpensive optical system with applications such as low-level fluorescence based analyte detection, single molecule imaging, and surface enhanced Raman studies. Preliminary results in single molecule experiments have also been obtained by imaging individual 3 nm and 20 nm dye-doped nanoparticles attached to the silver plasmonic gratings using epi-fluorescence microscopy.

Dual-modal cancer detection based on optical pH sensing and Raman spectroscopy.

Science.gov (United States)

Kim, Soogeun; Lee, Seung Ho; Min, Sun Young; Byun, Kyung Min; Lee, Soo Yeol

2017-10-01

A dual-modal approach using Raman spectroscopy and optical pH sensing was investigated to discriminate between normal and cancerous tissues. Raman spectroscopy has demonstrated the potential for in vivo cancer detection. However, Raman spectroscopy has suffered from strong fluorescence background of biological samples and subtle spectral differences between normal and disease tissues. To overcome those issues, pH sensing is adopted to Raman spectroscopy as a dual-modal approach. Based on the fact that the pH level in cancerous tissues is lower than that in normal tissues due to insufficient vasculature formation, the dual-modal approach combining the chemical information of Raman spectrum and the metabolic information of pH level can improve the specificity of cancer diagnosis. From human breast tissue samples, Raman spectra and pH levels are measured using fiber-optic-based Raman and pH probes, respectively. The pH sensing is based on the dependence of pH level on optical transmission spectrum. Multivariate statistical analysis is performed to evaluate the classification capability of the dual-modal method. The analytical results show that the dual-modal method based on Raman spectroscopy and optical pH sensing can improve the performance of cancer classification. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Fluorescence optical imaging in anticancer drug delivery.

Science.gov (United States)

Etrych, Tomáš; Lucas, Henrike; Janoušková, Olga; Chytil, Petr; Mueller, Thomas; Mäder, Karsten

2016-03-28

In the past several decades, nanosized drug delivery systems with various targeting functions and controlled drug release capabilities inside targeted tissues or cells have been intensively studied. Understanding their pharmacokinetic properties is crucial for the successful transition of this research into clinical practice. Among others, fluorescence imaging has become one of the most commonly used imaging tools in pre-clinical research. The development of increasing numbers of suitable fluorescent dyes excitable in the visible to near-infrared wavelengths of the spectrum has significantly expanded the applicability of fluorescence imaging. This paper focuses on the potential applications and limitations of non-invasive imaging techniques in the field of drug delivery, especially in anticancer therapy. Fluorescent imaging at both the cellular and systemic levels is discussed in detail. Additionally, we explore the possibility for simultaneous treatment and imaging using theranostics and combinations of different imaging techniques, e.g., fluorescence imaging with computed tomography. Copyright © 2016 Elsevier B.V. All rights reserved.

Bio-physically plausible visualization of highly scattering fluorescent neocortical models for in silico experimentation

KAUST Repository

Abdellah, Marwan

2017-02-15

Background We present a visualization pipeline capable of accurate rendering of highly scattering fluorescent neocortical neuronal models. The pipeline is mainly developed to serve the computational neurobiology community. It allows the scientists to visualize the results of their virtual experiments that are performed in computer simulations, or in silico. The impact of the presented pipeline opens novel avenues for assisting the neuroscientists to build biologically accurate models of the brain. These models result from computer simulations of physical experiments that use fluorescence imaging to understand the structural and functional aspects of the brain. Due to the limited capabilities of the current visualization workflows to handle fluorescent volumetric datasets, we propose a physically-based optical model that can accurately simulate light interaction with fluorescent-tagged scattering media based on the basic principles of geometric optics and Monte Carlo path tracing. We also develop an automated and efficient framework for generating dense fluorescent tissue blocks from a neocortical column model that is composed of approximately 31000 neurons. Results Our pipeline is used to visualize a virtual fluorescent tissue block of 50 μm3 that is reconstructed from the somatosensory cortex of juvenile rat. The fluorescence optical model is qualitatively analyzed and validated against experimental emission spectra of different fluorescent dyes from the Alexa Fluor family. Conclusion We discussed a scientific visualization pipeline for creating images of synthetic neocortical neuronal models that are tagged virtually with fluorescent labels on a physically-plausible basis. The pipeline is applied to analyze and validate simulation data generated from neuroscientific in silico experiments.

Biological applications of near-field scanning optical microscopy

Science.gov (United States)

Moers, Marco H. P.; Ruiter, A. G. T.; Jalocha, Alain; van Hulst, Niko F.; Kalle, W. H. J.; Wiegant, J. C. A. G.; Raap, A. K.

1995-09-01

Near-field Scanning Optical Microscopy (NSOM) is a true optical microscopic technique allowing fluorescence, absorption, reflection and polarization contrast with the additional advantage of nanometer lateral resolution, unlimited by diffraction and operation at ambient conditions. NSOM based on metal coated adiabatically tapered fibers, combined with shear force feedback and operated in illumination mode, has proven to be the most powerful NSOM arrangement, because of its true localization of the optical interaction, its various optical contrast possibilities and its sensitivity down to the single molecular level. In this paper applications of `aperture' NSOM to Fluorescence In Situ Hybridization of human metaphase chromosomes are presented, where the localized fluorescence allows to identify specific DNA sequences. All images are accompanied by the simultaneously acquired force image, enabling direct comparison of the optical contrast with the sample topography on nanometer scale, far beyond the diffraction limit. Thus the unique combination of high resolution, specific optical contrast and ambient operation offers many new direction possibilities in biological studies.

Fiber optic-based regenerable biosensor

Science.gov (United States)

Sepaniak, Michael J.; Vo-Dinh, Tuan

1993-01-01

A fiber optic-based regenerable biosensor. The biosensor is particularly suitable for use in microscale work in situ. In one embodiment, the biosensor comprises a reaction chamber disposed adjacent the distal end of a waveguide and adapted to receive therein a quantity of a sample containing an analyte. Leading into the chamber is a plurality of capillary conduits suitable for introducing into the chamber antibodies or other reagents suitable for selective interaction with a predetermined analyte. Following such interaction, the contents of the chamber may be subjected to an incident energy signal for developing fluorescence within the chamber that is detectable via the optical fiber and which is representative of the presence, i.e. concentration, of the selected analyte. Regeneration of the biosensor is accomplished by replacement of the reagents and/or the analyte, or a combination of these, at least in part via one or more of the capillary conduits. The capillary conduits extend from their respective terminal ends that are in fluid communication with the chamber, away from the chamber to respective location(s) remote from the chamber thereby permitting in situ location of the chamber and remote manipulation and/or analysis of the activity with the chamber.

Modification of Optical Properties of Seawater Exposed to Oil Contaminants Based on Excitation-Emission Spectra

Science.gov (United States)

Baszanowska, E.; Otremba, Z.

2015-10-01

The optical behaviour of seawater exposed to a residual amount of oil pollution is presented and a comparison of the fluorescence spectra of oil dissolved in both n-hexane and seawater is discussed based on excitation-emission spectra. Crude oil extracted from the southern part of the Baltic Sea was used to characterise petroleum properties after contact with seawater. The wavelength-independent fluorescence maximum for natural seawater and seawater artificially polluted with oil were determined. Moreover, the specific excitation-emission peaks for natural seawater and polluted water were analysed to identify the natural organic matter composition. It was found that fluorescence spectra identification is a promising method to detect even an extremely low concentration of petroleum residues directly in the seawater. In addition, alien substances disturbing the fluorescence signatures of natural organic substances in a marine environment is also discussed.

Fluorescence-Raman Dual Modal Endoscopic System for Multiplexed Molecular Diagnostics

Science.gov (United States)

Jeong, Sinyoung; Kim, Yong-Il; Kang, Homan; Kim, Gunsung; Cha, Myeong Geun; Chang, Hyejin; Jung, Kyung Oh; Kim, Young-Hwa; Jun, Bong-Hyun; Hwang, Do Won; Lee, Yun-Sang; Youn, Hyewon; Lee, Yoon-Sik; Kang, Keon Wook; Lee, Dong Soo; Jeong, Dae Hong

2015-03-01

Optical endoscopic imaging, which was recently equipped with bioluminescence, fluorescence, and Raman scattering, allows minimally invasive real-time detection of pathologies on the surface of hollow organs. To characterize pathologic lesions in a multiplexed way, we developed a dual modal fluorescence-Raman endomicroscopic system (FRES), which used fluorescence and surface-enhanced Raman scattering nanoprobes (F-SERS dots). Real-time, in vivo, and multiple target detection of a specific cancer was successful, based on the fast imaging capability of fluorescence signals and the multiplex capability of simultaneously detected SERS signals using an optical fiber bundle for intraoperative endoscopic system. Human epidermal growth factor receptor 2 (HER2) and epidermal growth factor receptor (EGFR) on the breast cancer xenografts in a mouse orthotopic model were successfully detected in a multiplexed way, illustrating the potential of FRES as a molecular diagnostic instrument that enables real-time tumor characterization of receptors during routine endoscopic procedures.

Compact whole-body fluorescent imaging of nude mice bearing EGFP expressing tumor

Science.gov (United States)

Chen, Yanping; Xiong, Tao; Chu, Jun; Yu, Li; Zeng, Shaoqun; Luo, Qingming

2005-01-01

Issue of tumor has been a hotspot of current medicine. It is important for tumor research to detect tumors bearing in animal models easily, fast, repetitively and noninvasivly. Many researchers have paid their increasing interests on the detecting. Some contrast agents, such as green fluorescent protein (GFP) and Discosoma red fluorescent protein (Dsred) were applied to enhance image quality. Three main kinds of imaging scheme were adopted to visualize fluorescent protein expressing tumors in vivo. These schemes based on fluorescence stereo microscope, cooled charge-coupled-device (CCD) or camera as imaging set, and laser or mercury lamp as excitation light source. Fluorescence stereo microscope, laser and cooled CCD are expensive to many institutes. The authors set up an inexpensive compact whole-body fluorescent imaging tool, which consisted of a Kodak digital camera (model DC290), fluorescence filters(B and G2;HB Optical, Shenyang, Liaoning, P.R. China) and a mercury 50-W lamp power supply (U-LH50HG;Olympus Optical, Japan) as excitation light source. The EGFP was excited directly by mercury lamp with D455/70 nm band-pass filter and fluorescence was recorded by digital camera with 520nm long-pass filter. By this easy operation tool, the authors imaged, in real time, fluorescent tumors growing in live mice. The imaging system is external and noninvasive. For half a year our experiments suggested the imaging scheme was feasible. Whole-body fluorescence optical imaging for fluorescent expressing tumors in nude mouse is an ideal tool for antitumor, antimetastatic, and antiangiogenesis drug screening.

Lab-on-fiber electrophoretic trace mixture separating and detecting an optofluidic device based on a microstructured optical fiber.

Science.gov (United States)

Yang, Xinghua; Guo, Xiaohui; Li, Song; Kong, Depeng; Liu, Zhihai; Yang, Jun; Yuan, Libo

2016-04-15

We report an in-fiber integrated electrophoretic trace mixture separating and detecting an optofluidic optical fiber sensor based on a specially designed optical fiber. In this design, rapid in situ separation and simultaneous detection of mixed analytes can be realized under electro-osmotic flow in the microstructured optical fiber. To visually display the in-fiber separating and detecting process, two common fluorescent indicators are adopted as the optofluidic analytes in the optical fiber. Results show that a trace amount of the mixture (0.15 μL) can be completely separated within 3.5 min under a high voltage of 5 kV. Simultaneously, the distributed information of the separated analytes in the optical fiber can be clearly obtained by scanning along the optical fiber using a 355 nm laser. The emission from the analytes can be efficiently coupled into the inner core and guides to the remote end of the optical fiber. In addition, the thin cladding around the inner core in the optical fiber can prevent the fluorescent cross talk between the analytes in this design. Compared to previous optical fiber optofluidic devices, this device first realizes simultaneously separating treatment and the detection of the mixed samples in an optical fiber. Significantly, such an in-fiber integrated separating and detecting optofluidic device can find wide applications in various analysis fields involves mixed samples, such as biology, chemistry, and environment.

Improving the Sensitivity and Functionality of Mobile Webcam-Based Fluorescence Detectors for Point-of-Care Diagnostics in Global Health

Science.gov (United States)

Rasooly, Reuven; Bruck, Hugh Alan; Balsam, Joshua; Prickril, Ben; Ossandon, Miguel; Rasooly, Avraham

2016-01-01

Resource-poor countries and regions require effective, low-cost diagnostic devices for accurate identification and diagnosis of health conditions. Optical detection technologies used for many types of biological and clinical analysis can play a significant role in addressing this need, but must be sufficiently affordable and portable for use in global health settings. Most current clinical optical imaging technologies are accurate and sensitive, but also expensive and difficult to adapt for use in these settings. These challenges can be mitigated by taking advantage of affordable consumer electronics mobile devices such as webcams, mobile phones, charge-coupled device (CCD) cameras, lasers, and LEDs. Low-cost, portable multi-wavelength fluorescence plate readers have been developed for many applications including detection of microbial toxins such as C. Botulinum A neurotoxin, Shiga toxin, and S. aureus enterotoxin B (SEB), and flow cytometry has been used to detect very low cell concentrations. However, the relatively low sensitivities of these devices limit their clinical utility. We have developed several approaches to improve their sensitivity presented here for webcam based fluorescence detectors, including (1) image stacking to improve signal-to-noise ratios; (2) lasers to enable fluorescence excitation for flow cytometry; and (3) streak imaging to capture the trajectory of a single cell, enabling imaging sensors with high noise levels to detect rare cell events. These approaches can also help to overcome some of the limitations of other low-cost optical detection technologies such as CCD or phone-based detectors (like high noise levels or low sensitivities), and provide for their use in low-cost medical diagnostics in resource-poor settings. PMID:27196933

Improving the Sensitivity and Functionality of Mobile Webcam-Based Fluorescence Detectors for Point-of-Care Diagnostics in Global Health

Directory of Open Access Journals (Sweden)

Reuven Rasooly

2016-05-01

Full Text Available Resource-poor countries and regions require effective, low-cost diagnostic devices for accurate identification and diagnosis of health conditions. Optical detection technologies used for many types of biological and clinical analysis can play a significant role in addressing this need, but must be sufficiently affordable and portable for use in global health settings. Most current clinical optical imaging technologies are accurate and sensitive, but also expensive and difficult to adapt for use in these settings. These challenges can be mitigated by taking advantage of affordable consumer electronics mobile devices such as webcams, mobile phones, charge-coupled device (CCD cameras, lasers, and LEDs. Low-cost, portable multi-wavelength fluorescence plate readers have been developed for many applications including detection of microbial toxins such as C. Botulinum A neurotoxin, Shiga toxin, and S. aureus enterotoxin B (SEB, and flow cytometry has been used to detect very low cell concentrations. However, the relatively low sensitivities of these devices limit their clinical utility. We have developed several approaches to improve their sensitivity presented here for webcam based fluorescence detectors, including (1 image stacking to improve signal-to-noise ratios; (2 lasers to enable fluorescence excitation for flow cytometry; and (3 streak imaging to capture the trajectory of a single cell, enabling imaging sensors with high noise levels to detect rare cell events. These approaches can also help to overcome some of the limitations of other low-cost optical detection technologies such as CCD or phone-based detectors (like high noise levels or low sensitivities, and provide for their use in low-cost medical diagnostics in resource-poor settings.

CsPbBr3 Perovskite Quantum Dots-Based Monolithic Electrospun Fiber Membrane as an Ultrastable and Ultrasensitive Fluorescent Sensor in Aqueous Medium.

Science.gov (United States)

Wang, Yuanwei; Zhu, Yihua; Huang, Jianfei; Cai, Jin; Zhu, Jingrun; Yang, Xiaoling; Shen, Jianhua; Jiang, Hao; Li, Chunzhong

2016-11-03

Perovskite quantum dots with excellent optical properties and robust durability stand as an appealing and desirable candidate for fluorescence resonance energy transfer (FRET) based fluorescence detection, a powerful technique featuring excellent accuracy and convenience. In this work, a monolithic superhydrophobic polystyrene fiber membrane with CsPbBr 3 perovskite quantum dots encapsulated within (CPBQDs/PS FM) was prepared via one-step electrospinning. Coupling CPBQDs with PS matrix, this CPBQDs/PS FM composite exhibits high quantum yields (∼91%), narrow half-peak width (∼16 nm), nearly 100% fluorescence retention after being exposed to water for 10 days and 79.80% fluorescence retention after 365 nm UV-light (1 mW/cm 2 ) illumination for 60 h. Thanks to the outstanding optical property of CPBQDs, an ultralow detection limit of 0.01 ppm was obtained for Rhodamine 6G (R6G) detection, with the FRET efficiency calculated to be 18.80% in 1 ppm R6G aqueous solution. Electrospun as well-designed fiber membranes, CPBQDs/PS FM composite also possesses good tailorability and recyclability, showing exciting potential for future implementation into practical applications.

Improved Optical Fiber Chemical Sensors

Science.gov (United States)

Egalon, Claudio O.; Rogowski, Robert S.

1994-01-01

Calculations, based on exact theory of optical fiber, have shown how to increase optical efficiency sensitivity of active-core, step-index-profile optical-fiber fluorosensor. Calculations result of efforts to improve efficiency of optical-fiber chemical sensor of previous concept described in "Making Optical-Fiber Chemical Sensors More Sensitive" (LAR-14525). Optical fiber chemical detector of enhanced sensitivity made in several configurations. Portion of fluorescence or chemiluminescence generated in core, and launched directly into bound electromagnetic modes that propagate along core to photodetector.

Chromophore photophysics and dynamics in fluorescent proteins of the GFP family

International Nuclear Information System (INIS)

Nienhaus, Karin; Nienhaus, G Ulrich

2016-01-01

Proteins of the green fluorescent protein (GFP) family are indispensable for fluorescence imaging experiments in the life sciences, particularly of living specimens. Their essential role as genetically encoded fluorescence markers has motivated many researchers over the last 20 years to further advance and optimize these proteins by using protein engineering. Amino acids can be exchanged by site-specific mutagenesis, starting with naturally occurring proteins as templates. Optical properties of the fluorescent chromophore are strongly tuned by the surrounding protein environment, and a targeted modification of chromophore-protein interactions requires a profound knowledge of the underlying photophysics and photochemistry, which has by now been well established from a large number of structural and spectroscopic experiments and molecular-mechanical and quantum-mechanical computations on many variants of fluorescent proteins. Nevertheless, such rational engineering often does not meet with success and thus is complemented by random mutagenesis and selection based on the optical properties. In this topical review, we present an overview of the key structural and spectroscopic properties of fluorescent proteins. We address protein-chromophore interactions that govern ground state optical properties as well as processes occurring in the electronically excited state. Special emphasis is placed on photoactivation of fluorescent proteins. These light-induced reactions result in large structural changes that drastically alter the fluorescence properties of the protein, which enables some of the most exciting applications, including single particle tracking, pulse chase imaging and super-resolution imaging. We also present a few examples of fluorescent protein application in live-cell imaging experiments. (topical review)

Chromophore photophysics and dynamics in fluorescent proteins of the GFP family

Science.gov (United States)

Nienhaus, Karin; Nienhaus, G. Ulrich

2016-11-01

Proteins of the green fluorescent protein (GFP) family are indispensable for fluorescence imaging experiments in the life sciences, particularly of living specimens. Their essential role as genetically encoded fluorescence markers has motivated many researchers over the last 20 years to further advance and optimize these proteins by using protein engineering. Amino acids can be exchanged by site-specific mutagenesis, starting with naturally occurring proteins as templates. Optical properties of the fluorescent chromophore are strongly tuned by the surrounding protein environment, and a targeted modification of chromophore-protein interactions requires a profound knowledge of the underlying photophysics and photochemistry, which has by now been well established from a large number of structural and spectroscopic experiments and molecular-mechanical and quantum-mechanical computations on many variants of fluorescent proteins. Nevertheless, such rational engineering often does not meet with success and thus is complemented by random mutagenesis and selection based on the optical properties. In this topical review, we present an overview of the key structural and spectroscopic properties of fluorescent proteins. We address protein-chromophore interactions that govern ground state optical properties as well as processes occurring in the electronically excited state. Special emphasis is placed on photoactivation of fluorescent proteins. These light-induced reactions result in large structural changes that drastically alter the fluorescence properties of the protein, which enables some of the most exciting applications, including single particle tracking, pulse chase imaging and super-resolution imaging. We also present a few examples of fluorescent protein application in live-cell imaging experiments.

Wide Field-of-View Fluorescence Imaging with Optical-Quality Curved Microfluidic Chamber for Absolute Cell Counting

Directory of Open Access Journals (Sweden)

Mohiuddin Khan Shourav

2016-07-01

Full Text Available Field curvature and other aberrations are encountered inevitably when designing a compact fluorescence imaging system with a simple lens. Although multiple lens elements can be used to correct most such aberrations, doing so increases system cost and complexity. Herein, we propose a wide field-of-view (FOV fluorescence imaging method with an unconventional optical-quality curved sample chamber that corrects the field curvature caused by a simple lens. Our optics simulations and proof-of-concept experiments demonstrate that a curved substrate with lens-dependent curvature can reduce greatly the distortion in an image taken with a conventional planar detector. Following the validation study, we designed a curved sample chamber that can contain a known amount of sample volume and fabricated it at reasonable cost using plastic injection molding. At a magnification factor of approximately 0.6, the curved chamber provides a clear view of approximately 119 mm2, which is approximately two times larger than the aberration-free area of a planar chamber. Remarkably, a fluorescence image of microbeads in the curved chamber exhibits almost uniform intensity over the entire field even with a simple lens imaging system, whereas the distorted boundary region has much lower brightness than the central area in the planar chamber. The absolute count of white blood cells stained with a fluorescence dye was in good agreement with that obtained by a commercially available conventional microscopy system. Hence, a wide FOV imaging system with the proposed curved sample chamber would enable us to acquire an undistorted image of a large sample volume without requiring a time-consuming scanning process in point-of-care diagnostic applications.

Fluorescence detection system for microfluidic droplets

Science.gov (United States)

Chen, Binyu; Han, Xiaoming; Su, Zhen; Liu, Quanjun

2018-05-01

In microfluidic detection technology, because of the universality of optical methods in laboratory, optical detection is an attractive solution for microfluidic chip laboratory equipment. In addition, the equipment with high stability and low cost can be realized by integrating appropriate optical detection technology on the chip. This paper reports a detection system for microfluidic droplets. Photomultiplier tubes (PMT) is used as a detection device to improve the sensitivity of detection. This system improves the signal to noise ratio by software filtering and spatial filter. The fluorescence intensity is proportional to the concentration of the fluorescence and intensity of the laser. The fluorescence micro droplets of different concentrations can be distinguished by this system.

All Fiber-Coupled OH Planar Laser-Induced-Fluorescence (OH-PLIF)-Based Two-Dimensional Thermometry.

Science.gov (United States)

Hsu, Paul S; Jiang, Naibo; Patnaik, Anil K; Katta, Vish; Roy, Sukesh; Gord, James R

2018-04-01

Two-color, planar laser-induced fluorescence (PLIF)-based two-dimensional (2D) thermometry techniques for reacting flows, which are typically developed in the laboratory conditions, face a stiff challenge in their practical implementation in harsh environments such as combustion rigs. In addition to limited optical access, the critical experimental conditions (i.e., uncontrolled humidity, vibration, and large thermal gradients) often restrict sensitive laser system operation and cause difficulties maintaining beam-overlap. Thus, an all fiber-coupled, two-color OH-PLIF system has been developed, employing two long optical fibers allowing isolation of the laser and signal-collection systems. Two OH-excitation laser beams (∼283 nm and ∼286 nm) are delivered through a common 6 m long, 400 µm core, deep ultraviolet (UV)-enhanced multimode fiber. The fluorescence signal (∼310 nm) is collected by a 3 m long, UV-grade imaging fiber. Proof-of-principle temperature measurements are demonstrated in atmospheric pressure, near adiabatic, CH 4 /O 2 /N 2 jet flames. The effects of the excitation pulse interval on fiber transmission are investigated. The proof-of-principle measurements show significant promise for thermometry in harsh environments such as gas turbine engine tests.

Laboratory-based recording of holographic fine structure in X-ray absorption anisotropy using polycapillary optics

Energy Technology Data Exchange (ETDEWEB)

Dabrowski, K.M. [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland); Korecki, P., E-mail: pawel.korecki@uj.edu.pl [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)

2012-08-15

Highlights: Black-Right-Pointing-Pointer Holographic fine structures in X-ray absorption recorded using a tabletop setup. Black-Right-Pointing-Pointer Setup based on polycapillary collimating optics and an HOPG crystal. Black-Right-Pointing-Pointer Demonstration of element sensitivity by detection of X-ray fluorescence. Black-Right-Pointing-Pointer Potential of laboratory-based experiments for heavily doped crystals and thin films. - Abstract: A tabletop setup composed of a collimating polycapillary optics and a highly oriented pyrolytic graphite monochromator (HOPG) was characterized and used for recording two-dimensional maps of X-ray absorption anisotropy (XAA). XAA originates from interference of X-rays directly inside the sample. Depending on experimental conditions, fine structures in XAA can be interpreted in terms of X-ray holograms or X-ray standing waves and can be used for an element selective atomic-resolved structural analysis. The implementation of polycapillary optics resulted in a two-order of magnitude gain in the radiant intensity (photons/s/solid angle) as compared to a system without optics and enabled efficient recording of XAA with a resolution of 0.15 Degree-Sign for Mo K{alpha} radiation. Element sensitivity was demonstrated by acquisition of distinct XAA signals for Ga and As atoms in a GaAs (1 1 1) wafer by using X-ray fluorescence as a secondary signal. These results indicate the possibility of performing laboratory-based XAA experiments for heavily doped single crystals or thin films. So far, because of the weak holographic modulation of XAA, such experiments could be only performed using synchrotron radiation.

A highly selective fluorescent chemosensor for CN- based on a novel bis(salamo)-type tetraoxime ligand

Science.gov (United States)

Wang, Fei; Gao, Lei; Zhao, Qing; Zhang, Yang; Dong, Wen-Kui; Ding, Yu-Jie

2018-02-01

The optical properties of a novel chemosensor for cyanide anions based on a symmetric bis(salamo)-type ligand (H3L) were investigated by UV-Vis and fluorescence spectroscopy in MeOH/H2O (1:1 v/v) solution. Sensor H3L can selectively sense CN- based on prominent color changes among other anions. The chemosensor exhibits an apparent fluorescence enhancement at 482 nm to CN- which because cyanide ions interact with Cdbnd N bonds. Combining the corrected Benesi-Hildebrand formula, the binding constant of the formed host-guest complex was calculated as 2.42 × 105 M- 1. Meanwhile, the detection limit of the sensor toward CN- was 8.91 × 10- 7 M. It is worth noting that the designed sensor can be used for rapid detection of cyanide anions in basic pH range, and has great practical value.

Reconstruction for limited-projection fluorescence molecular tomography based on projected restarted conjugate gradient normal residual.

Science.gov (United States)

Cao, Xu; Zhang, Bin; Liu, Fei; Wang, Xin; Bai, Jing

2011-12-01

Limited-projection fluorescence molecular tomography (FMT) can greatly reduce the acquisition time, which is suitable for resolving fast biology processes in vivo but suffers from severe ill-posedness because of the reconstruction using only limited projections. To overcome the severe ill-posedness, we report a reconstruction method based on the projected restarted conjugate gradient normal residual. The reconstruction results of two phantom experiments demonstrate that the proposed method is feasible for limited-projection FMT. © 2011 Optical Society of America

Quantum sized Ag nanocluster assisted fluorescence enhancement in Tm3+-Yb3+ doped optical fiber beyond plasmonics

International Nuclear Information System (INIS)

Chattopadhyay, Rik; Haldar, Arindam; Paul, Mukul C.; Das, Shyamal; Bhadra, Shyamal K.

2015-01-01

We report a process for enhancing fluorescence emission from conventional rare earth ions in optical fiber by metal nanocluster (MNC) in nonresonant indirect pumping. The process is completely different from formal metal enhanced fluorescence phenomenon as the MNCs are too small in size to support localized surface plasmon and the excitation wavelength is far from plasmon resonance frequency. We used an established theory of two coupled oscillators to explain the simultaneous enhancement of Ytterbium (Yb 3+ ) and Thulium (Tm 3+ ) emission by silver (Ag) NCs under nonresonant pumping in optical fiber. The fiber is pumped with a 980 nm fiber pigtailed laser diode with input power of 20–100 mW to excite the Yb 3+ . Four times enhancement of Yb 3+ emission of 900–1100 nm and Tm 3+ upconversion emission around 474 nm, 650 nm, and 790 nm is observed in the fiber with Ag NCs

Fluorescence-Based Bioassays for the Detection and Evaluation of Food Materials

OpenAIRE

Nishi, Kentaro; Isobe, Shin-Ichiro; Zhu, Yun; Kiyama, Ryoiti

2015-01-01

We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based mi...

Bright and photostable nitrogen-vacancy fluorescence from unprocessed detonation nanodiamond.

Science.gov (United States)

Reineck, P; Capelli, M; Lau, D W M; Jeske, J; Field, M R; Ohshima, T; Greentree, A D; Gibson, B C

2017-01-05

Bright and photostable fluorescence from nitrogen-vacancy (NV) centers is demonstrated in unprocessed detonation nanodiamond particle aggregates. The optical properties of these particles is analyzed using confocal fluorescence microscopy and spectroscopy, time resolved fluorescence decay measurements, and optically detected magnetic resonance experiments. Two particle populations with distinct optical properties are identified and compared to high-pressure high-temperature (HPHT) fluorescent nanodiamonds. We find that the brightness of one detonation nanodiamond particle population is on the same order as that of highly processed fluorescent 100 nm HPHT nanodiamonds. Our results may open the path to a simple and up-scalable route for the production of fluorescent NV nanodiamonds for use in bioimaging applications.

Oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor: Sensing ability, TD-DFT calculations and its application as an efficient solid state sensor

Science.gov (United States)

Lan, Linxin; Li, Tianduo; Wei, Tao; Pang, He; Sun, Tao; Wang, Enhua; Liu, Haixia; Niu, Qingfen

2018-03-01

An oligothiophene-based colorimetric and ratiometric fluorescence dual-channel cyanide chemosensor 3 T-2CN was reported. Sensor 3 T-2CN showed both naked-eye recognition and ratiometric fluorescence response for CN- with an excellent selectivity and high sensitivity. The sensing mechanism based on the nucleophilic attack of CN- on the vinyl Cdbnd C bond has been successfully confirmed by the optical measurements, 1H NMR titration, FT-IR spectra as well as the DFT/TD-DFT calculations. Moreover, the detection limit was calculated to be 0.19 μM, which is much lower than the maximum permission concentration in drinking water (1.9 μM). Importantly, test strips (filter paper and TLC plates) containing 3 T-2CN were fabricated, which could act as a practical and efficient solid state optical sensor for CN- in field measurements.

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)

Quantitative frequency-domain fluorescence spectroscopy in tissues and tissue-like media

Science.gov (United States)

Cerussi, Albert Edward

1999-09-01

In the never-ending quest for improved medical technology at lower cost, modern near-infrared optical spectroscopy offers the possibility of inexpensive technology for quantitative and non-invasive diagnoses. Hemoglobin is the dominant chromophore in the 700-900 nm spectral region and as such it allows for the optical assessment of hemoglobin concentration and tissue oxygenation by absorption spectroscopy. However, there are many other important physiologically relevant compounds or physiological states that cannot be effectively sensed via optical methods because of poor optical contrast. In such cases, contrast enhancements are required. Fluorescence spectroscopy is an attractive component of optical tissue spectroscopy. Exogenous fluorophores, as well as some endogenous ones, may furnish the desperately needed sensitivity and specificity that is lacking in near-infrared optical tissue spectroscopy. The main focus of this thesis was to investigate the generation and propagation of fluorescence photons inside tissues and tissue-like media (i.e., scattering dominated media). The standard concepts of fluorescence spectroscopy have been incorporated into a diffusion-based picture that is sometimes referred to as photon migration. The novelty of this work lies in the successful quantitative recovery of fluorescence lifetimes, absolute fluorescence quantum yields, fluorophore concentrations, emission spectra, and both scattering and absorption coefficients at the emission wavelength from a tissue-like medium. All of these parameters are sensitive to the fluorophore local environment and hence are indicators of the tissue's physiological state. One application demonstrating the capabilities of frequency-domain lifetime spectroscopy in tissue-like media is a study of the binding of ethidium bromide to bovine leukocytes in fresh milk. Ethidium bromide is a fluorescent dye that is commonly used to label DNA, and hence visualize chromosomes in cells. The lifetime of

A simple triazole-based “turn on” fluorescent sensor for Al3+ ion in MeCN–H2O and F− ion in MeCN

International Nuclear Information System (INIS)

Erdemir, Serkan; Malkondu, Sait

2015-01-01

A novel fluorescent sensor N-((2-hydroxynaphthalen-1-yl)methylene)-1H-1,2,4-triazole-3-carbohydrazide (NTA), based on triazole was synthesized in two facile steps, characterized systematically and used as a turn-on fluorescent sensor for both Al 3+ and F − . The fluorescence spectra changes showed that NTA is highly selective for Al 3+ over other metal ions in MeCN–H 2 O solution. The receptor NTA could also sense F − selectively in MeCN. The complexation properties of receptor NTA with Al 3+ and F − ions were observed by 1 H NMR titration experiments. - Highlights: • A novel fluorescent sensor based on triazole was synthesized in two steps and fully characterized. • The optical properties of NTA were observed by UV–visible and fluorescence spectroscopy. • NTA showed high selectivity and sensitivity to Al 3+ cation and F − anion

Automatic classification of fluorescence and optical diffusion spectroscopy data in neuro-oncology

Science.gov (United States)

Savelieva, T. A.; Loshchenov, V. B.; Goryajnov, S. A.; Potapov, A. A.

2018-04-01

The complexity of the biological tissue spectroscopic analysis due to the overlap of biological molecules' absorption spectra, multiple scattering effect, as well as measurement geometry in vivo has caused the relevance of this work. In the neurooncology the problem of tumor boundaries delineation is especially acute and requires the development of new methods of intraoperative diagnosis. Methods of optical spectroscopy allow detecting various diagnostically significant parameters non-invasively. 5-ALA induced protoporphyrin IX is frequently used as fluorescent tumor marker in neurooncology. At the same time analysis of the concentration and the oxygenation level of haemoglobin and significant changes of light scattering in tumor tissues have a high diagnostic value. This paper presents an original method for the simultaneous registration of backward diffuse reflectance and fluorescence spectra, which allows defining all the parameters listed above simultaneously. The clinical studies involving 47 patients with intracranial glial tumors of II-IV Grades were carried out in N.N. Burdenko National Medical Research Center of Neurosurgery. To register the spectral dependences the spectroscopic system LESA- 01-BIOSPEC was used with specially developed w-shaped diagnostic fiber optic probe. The original algorithm of combined spectroscopic signal processing was developed. We have created a software and hardware, which allowed (as compared with the methods currently used in neurosurgical practice) to increase the sensitivity of intraoperative demarcation of intracranial tumors from 78% to 96%, specificity of 60% to 82%. The result of analysis of different techniques of automatic classification shows that in our case the most appropriate is the k Nearest Neighbors algorithm with cubic metrics.

A dual-stimuli-responsive fluorescent switch ultrathin film

Science.gov (United States)

Li, Zhixiong; Liang, Ruizheng; Liu, Wendi; Yan, Dongpeng; Wei, Min

2015-10-01

Stimuli-responsive fluorescent switches have shown broad applications in optical devices, biological materials and intelligent responses. Herein, we describe the design and fabrication of a dual-stimuli-responsive fluorescent switch ultrathin film (UTF) via a three-step layer-by-layer (LBL) technique: (i) encapsulation of spiropyran (SP) within an amphiphilic block copolymer (PTBEM) to give the (SP@PTBEM) micelle; (ii) the mixture of riboflavin (Rf) and poly(styrene 4-sulfonate) (PSS) to enhance the adhesion ability of small molecules; (iii) assembly of negatively charged SP@PTBEM and Rf-PSS with cationic layered double hydroxide (LDH) nanoplatelets to obtain the (Rf-PSS/LDH/SP@PTBEM)n UTFs (n: bilayer number). The assembly process of the UTFs and their luminescence properties, as monitored by fluorescence spectroscopy and scanning electron microscopy (SEM), present a uniform and ordered layered structure with stepwise growth. The resulting Rf-PSS/LDH/SP@PTBEM UTF serves as a three-state switchable multicolor (green, yellow, and red) luminescent system based on stimulation from UV/Vis light and pH, with an acceptable reversibility. Therefore, this work provides a facile way to fabricate stimuli-responsive solid-state film switches with tunable-color luminescence, which have potential applications in the areas of displays, sensors, and rewritable optical memory and fluorescent logic devices.Stimuli-responsive fluorescent switches have shown broad applications in optical devices, biological materials and intelligent responses. Herein, we describe the design and fabrication of a dual-stimuli-responsive fluorescent switch ultrathin film (UTF) via a three-step layer-by-layer (LBL) technique: (i) encapsulation of spiropyran (SP) within an amphiphilic block copolymer (PTBEM) to give the (SP@PTBEM) micelle; (ii) the mixture of riboflavin (Rf) and poly(styrene 4-sulfonate) (PSS) to enhance the adhesion ability of small molecules; (iii) assembly of negatively charged SP

Quantitative estimation of the fluorescent parameters for crop leaves with the Bayesian inversion

Science.gov (United States)

In this study, the fluorescent parameters of crop leaves were retrieved from the leaf hyperspectral measurements by inverting the FluorMODleaf model, which is a leaf-level fluorescence model that is based on the widely used and validated PROSPECT (leaf optical properties) model and can simulate the ...

Study of the interaction of Tb (III) with dextran through fluorescence spectroscopy and optical rotatory dispersion

International Nuclear Information System (INIS)

Vasconcelos, Sandra S.; Rodrigues, J.F.

1984-01-01

A study of the interaction of Tb(III) with dextran in aqueous solution was perform using fluorescence spectroscopy and optical rotatory dispersion. The results indicate the formation of a complex with the displacent of water from the cation coordinated sphere by hydroxyl groups at the second and third carbon atoms of the monomer unit. (Author) [pt

Assisted Interpretation of Laser-Induced Fluorescence Spectra of Egg-Based Binding Media Using Total Emission Fluorescence Spectroscopy

International Nuclear Information System (INIS)

Anglos, D.; Nevin, A.

2006-01-01

Laser-induced fluorescence (LIF) spectroscopy can provide nondestructive, qualitative analysis of protein-based binding media found in artworks. Fluorescence emissions from proteins in egg yolk and egg white are due to auto fluorescent aromatic amino acids as well as other native and age-related fluorophores, but the potential of fluorescence spectroscopy for the differentiation between binding media is dependent on the choice of a suitable excitation wavelength and limited by problems in interpretation. However, a better understanding of emission spectra associated with LIF can be achieved following comparisons with total emission fluorescence spectra where a series of consecutive emission spectra are recorded over a specific range. Results using nanosecond UV laser sources for LIF of egg-based binding media are presented which are rationalised following comparisons with total emission spectra. Specifically, fluorescence is assigned to tryptophan and oxidation products of amino acids; in the case of egg yolk, fatty-acid polymerisation and age-related degradation products account for the formation of fluorophores.

Self-interference fluorescence microscopy with three-phase detection for depth-resolved confocal epi-fluorescence imaging.

Science.gov (United States)

Braaf, Boy; de Boer, Johannes F

2017-03-20

Three-dimensional confocal fluorescence imaging of in vivo tissues is challenging due to sample motion and limited imaging speeds. In this paper a novel method is therefore presented for scanning confocal epi-fluorescence microscopy with instantaneous depth-sensing based on self-interference fluorescence microscopy (SIFM). A tabletop epi-fluorescence SIFM setup was constructed with an annular phase plate in the emission path to create a spectral self-interference signal that is phase-dependent on the axial position of a fluorescent sample. A Mach-Zehnder interferometer based on a 3 × 3 fiber-coupler was developed for a sensitive phase analysis of the SIFM signal with three photon-counter detectors instead of a spectrometer. The Mach-Zehnder interferometer created three intensity signals that alternately oscillated as a function of the SIFM spectral phase and therefore encoded directly for the axial sample position. Controlled axial translation of fluorescent microsphere layers showed a linear dependence of the SIFM spectral phase with sample depth over axial image ranges of 500 µm and 80 µm (3.9 × Rayleigh range) for 4 × and 10 × microscope objectives respectively. In addition, SIFM was in good agreement with optical coherence tomography depth measurements on a sample with indocyanine green dye filled capillaries placed at multiple depths. High-resolution SIFM imaging applications are demonstrated for fluorescence angiography on a dye-filled capillary blood vessel phantom and for autofluorescence imaging on an ex vivo fly eye.

Spectroscopy and nonclassical fluorescence properties of single trapped Ba+ ions

International Nuclear Information System (INIS)

Bolle, J.

1998-06-01

This thesis reports on the setup and application of an experimental apparatus for spectroscopic and quantum optical investigations of a single Barium ion in a Paul trap. The realization of the apparatus, which consists of the ion trap in ultra high vacuum, two laser systems, and a photon counting detection system, is described in detail, with particular consideration of the noise sources like stray light and laser frequency instabilities. The two lasers at 493 nm and 650 nm needed to continuously excite resonance fluorescence from the Barium ion have been realized using diode lasers only. The preparation of a single localized Barium ion is described, in particular its optical cooling with the laser light and the minimization of induced vibration in the trapping potential. The purely quantum mechanical property of antibunching is observed by measuring the intensity correlation function of resonance fluorescence from the trapped and cooled ion. Interference properties of the single ion resonance fluorescence are investigated with a Mach-Zehnder interferometer. From the measured high-contrast interference signal it is proven that each individual fluorescence photon interferes with itself. The fluorescence excitation spectrum, on varying one laser frequency, is also measured and exhibits dark resonances. These measurements are compared to calculations based on optical Bloch equations for the 8 atomic levels involved. Future experiments, in particular the detection of reduced quantum fluctuations (squeezing) in one quadrature component of the resonance fluorescence, are discussed. (author)

Riboflavin enhanced fluorescence of highly reduced graphene oxide

Science.gov (United States)

Iliut, Maria; Gabudean, Ana-Maria; Leordean, Cosmin; Simon, Timea; Teodorescu, Cristian-Mihail; Astilean, Simion

2013-10-01

The improvement of graphene derivates' fluorescence properties is a challenging topic and very few ways were reported up to now. In this Letter we propose an easy method to enhance the fluorescence of highly reduced graphene oxide (rGO) through non-covalent binding to a molecular fluorophore, namely the riboflavin (Rb). While the fluorescence of Rb is quenched, the Rb - decorated rGO exhibits strong blue fluorescence and significantly increased fluorescence lifetime, as compared to its pristine form. The data reported here represent a promising start towards tailoring the optical properties of rGOs, having utmost importance in optical applications.

Validating Intravascular Imaging with Serial Optical Coherence Tomography and Confocal Fluorescence Microscopy.

Science.gov (United States)

Tardif, Pier-Luc; Bertrand, Marie-Jeanne; Abran, Maxime; Castonguay, Alexandre; Lefebvre, Joël; Stähli, Barbara E; Merlet, Nolwenn; Mihalache-Avram, Teodora; Geoffroy, Pascale; Mecteau, Mélanie; Busseuil, David; Ni, Feng; Abulrob, Abedelnasser; Rhéaume, Éric; L'Allier, Philippe; Tardif, Jean-Claude; Lesage, Frédéric

2016-12-15

Atherosclerotic cardiovascular diseases are characterized by the formation of a plaque in the arterial wall. Intravascular ultrasound (IVUS) provides high-resolution images allowing delineation of atherosclerotic plaques. When combined with near infrared fluorescence (NIRF), the plaque can also be studied at a molecular level with a large variety of biomarkers. In this work, we present a system enabling automated volumetric histology imaging of excised aortas that can spatially correlate results with combined IVUS/NIRF imaging of lipid-rich atheroma in cholesterol-fed rabbits. Pullbacks in the rabbit aortas were performed with a dual modality IVUS/NIRF catheter developed by our group. Ex vivo three-dimensional (3D) histology was performed combining optical coherence tomography (OCT) and confocal fluorescence microscopy, providing high-resolution anatomical and molecular information, respectively, to validate in vivo findings. The microscope was combined with a serial slicer allowing for the imaging of the whole vessel automatically. Colocalization of in vivo and ex vivo results is demonstrated. Slices can then be recovered to be tested in conventional histology.

Optical properties of individual nano-sized gold particle pairs. Mie-scattering, fluorescence, and Raman-scattering

Energy Technology Data Exchange (ETDEWEB)

Olk, Phillip

2008-07-01

This thesis examines and exploits the optical properties of pairs of MNPs. Pairs of MNPs offer two further parameters not existent at single MNPs, which both affect the local optical fields in their vicinity: the distance between them, and their relative orientation with respect to the polarisation of the excitation light. These properties are subject of three chapters: One section examines the distance-dependent and orientation-sensitive scattering cross section (SCS) of two equally sized MNPs. Both near- and far-field interactions affect the spectral position and spectral width of the SCS. Far-field coupling affects the SCS even in such a way that a two-particle system may show both a blue- and redshifted SCS, depending only on the distance between the two MNPs. The maximum distance for this effect is the coherence length of the illumination source - a fact of importance for SCS-based experiments using laser sources. Another part of this thesis examines the near-field between two MNPs and the dependence of the locally enhanced field on the relative particle orientation with respect to the polarisation of the excitation light. To attain a figure of merit, the intensity of fluorescence light from dye molecules in the surrounding medium was measured at various directions of polarisation. The field enhancement was turned into fluorescence enhancement, even providing a means for sensing the presence of very small MNPs of 12 nm in diameter. In order to quantify the near-field experimentally, a different technique is devised in a third section of this thesis - scanning particle-enhanced Raman microscopy (SPRM). This device comprises a scanning probe carrying an MNP which in turn is coated with a molecule of known Raman signature. By manoeuvring this outfit MNP into the vicinity of an illuminated second MNP and by measuring the Raman signal intensity, a spatial mapping of the field enhancement was possible. (orig.)

Characterization of tapered polymer optical fibers under side illumination for fluorescence sensing applications

Science.gov (United States)

Pulido, C.; Esteban, Ó.

2011-05-01

In this work we present the fabrication and characterization of tapered polymer fibers used as fluorescence based sensors with a side-illumination arrangement. The fabrication method consists of a travelling-heater that gives a tight control of the tapered fibers parameters, namely the taper waist and the profile of the transition length between the unaltered fiber and the taper waist. Furthermore, a different approach for using fluorophores in fluorescence based sensors has been developed. With our method, we can locally introduce a fluorescent dye inside the taper region, which could lead to the generation of cuasi-distributed sensors for lengths of hundred of meters.

Chemodosimeter-based fluorescent detection of L-cysteine after extracted by molecularly imprinted polymers.

Science.gov (United States)

Cai, Xiaoqiang; Li, Jinhua; Zhang, Zhong; Wang, Gang; Song, Xingliang; You, Jinmao; Chen, Lingxin

2014-03-01

A chemodosimeter-based fluorescent detection method coupled with molecularly imprinted polymers (MIPs) extraction was developed for determination of L-cysteine (L-Cys) by combining molecular imprinting technique with fluorescent chemodosimeter. The MIPs prepared by precipitation polymerization with L-Cys as template, possessed high specific surface area of 145 m(2)/g and good thermal stability without decomposition lower than 300 °C, and were successfully applied as an adsorbent with excellent selectivity for L-Cys over other amino acids, and enantioselectivity was also demonstrated. A novel chemodosimeter, rhodamine B1, was synthesized for discriminating L-Cys from its structurally similar homocysteine and glutathione as well as various possibly co-existing biospecies in aqueous solutions with notable fluorescence enhancement when adding L-Cys. As L-Cys was added with increasing concentrations, an emission band peaked at 580 nm occurred and significantly increased in fluorescence intensity, by which the L-Cys could be sensed optically. High detectability up to 12.5 nM was obtained. An excellent linearity was found within the wide range of 0.05-50 μM (r=0.9996), and reasonable relative standard deviations ranging from 0.3% to 3.5% were attained. Such typical features as high selectivity, high sensitivity, easy operation and low cost enabled this MIPs-fluorometry to be potentially applicable for routine detection of trace L-Cys. Copyright © 2013 Elsevier B.V. All rights reserved.

Simultaneous determination of glycols based on fluorescence anisotropy

International Nuclear Information System (INIS)

Garcia Sanchez, F.; Navas Diaz, A.; Lopez Guerrero, M.M.

2007-01-01

Simultaneous determination of non-fluorescent glycols in mixtures without separation or chemical transformation steps is described. Two methods based in the measure of fluorescence anisotropy of a probe such as fluorescein dissolved in the analyte or analyte mixtures are described. In the first method, the anisotropy spectra of pure and mixtures of analytes are used to quantitative determination (if the fluorophor concentration is in a range where fluorescence intensity is proportional to concentration). In the second method, a calibration curve anisotropy-concentration based on the application of the Perrin equation is established. The methods presented here are capable of directly resolving binary mixtures of non-fluorescent glycols on the basis of differences on the fluorescence anisotropy of a fluorescence tracer. Best analytical performances were obtained by application of the method based on Perrin equation. This method is simple, rapid and allows the determination of mixtures of glycols with reasonable accuracy and precision. Detection limits are limited by the quantum yield and anisotropy values of the tracer in the solvents. Recovery values are related to the differences in anisotropy values of the tracer in the pure solvents. Mixtures of glycerine/ethylene glycol (GL/EG), ethylene glycol/1,2-propane diol (EG/1,2-PPD) and polyethylene glycol 400/1,2-propane diol (PEG 400/1,2-PPD) were analysed and recovery values are within 95-120% in the Perrin method. Relative standard deviation are in the range 1.3-2.9% and detection limits in the range 3.9-8.9%

Polymer Optical Fiber Compound Parabolic Concentrator fiber tip based glucose sensor: In-Vitro Testing

DEFF Research Database (Denmark)

Hassan, Hafeez Ul; Janting, Jakob; Aasmul, Soren

2016-01-01

We present in-vitro sensing of glucose using a newly developed efficient optical fiber glucose sensor based on a Compound Parabolic Concentrator (CPC) tipped polymer optical fiber (POF). A batch of 9 CPC tipped POF sensors with a 35 mm fiber length is shown to have an enhanced fluorescence pickup...... efficiency with an average increment factor of 1.7 as compared to standard POF sensors with a plane cut fiber tip. Invitro measurements for two glucose concentrations (40 and 400 mg/dL) confirm that the CPC tipped sensors efficiently can detect both glucose concentrations. it sets the footnote at the bottom...

Dual-modal cancer detection based on optical pH sensing and Raman spectroscopy

Science.gov (United States)

Kim, Soogeun; Lee, Seung Ho; Min, Sun Young; Byun, Kyung Min; Lee, Soo Yeol

2017-10-01

A dual-modal approach using Raman spectroscopy and optical pH sensing was investigated to discriminate between normal and cancerous tissues. Raman spectroscopy has demonstrated the potential for in vivo cancer detection. However, Raman spectroscopy has suffered from strong fluorescence background of biological samples and subtle spectral differences between normal and disease tissues. To overcome those issues, pH sensing is adopted to Raman spectroscopy as a dual-modal approach. Based on the fact that the pH level in cancerous tissues is lower than that in normal tissues due to insufficient vasculature formation, the dual-modal approach combining the chemical information of Raman spectrum and the metabolic information of pH level can improve the specificity of cancer diagnosis. From human breast tissue samples, Raman spectra and pH levels are measured using fiber-optic-based Raman and pH probes, respectively. The pH sensing is based on the dependence of pH level on optical transmission spectrum. Multivariate statistical analysis is performed to evaluate the classification capability of the dual-modal method. The analytical results show that the dual-modal method based on Raman spectroscopy and optical pH sensing can improve the performance of cancer classification.

Full Field X-Ray Fluorescence Imaging Using Micro Pore Optics for Planetary Surface Exploration

Science.gov (United States)

Sarrazin, P.; Blake, D. F.; Gailhanou, M.; Walter, P.; Schyns, E.; Marchis, F.; Thompson, K.; Bristow, T.

2016-01-01

Many planetary surface processes leave evidence as small features in the sub-millimetre scale. Current planetary X-ray fluorescence spectrometers lack the spatial resolution to analyse such small features as they only provide global analyses of areas greater than 100 mm(exp 2). A micro-XRF spectrometer will be deployed on the NASA Mars 2020 rover to analyse spots as small as 120m. When using its line-scanning capacity combined to perpendicular scanning by the rover arm, elemental maps can be generated. We present a new instrument that provides full-field XRF imaging, alleviating the need for precise positioning and scanning mechanisms. The Mapping X-ray Fluorescence Spectrometer - "Map-X" - will allow elemental imaging with approximately 100µm spatial resolution and simultaneously provide elemental chemistry at the scale where many relict physical, chemical and biological features can be imaged in ancient rocks. The arm-mounted Map-X instrument is placed directly on the surface of an object and held in a fixed position during measurements. A 25x25 mm(exp 2) surface area is uniformly illuminated with X-rays or alpha-particles and gamma-rays. A novel Micro Pore Optic focusses a fraction of the emitted X-ray fluorescence onto a CCD operated at a few frames per second. On board processing allows measuring the energy and coordinates of each X-ray photon collected. Large sets of frames are reduced into 2d histograms used to compute higher level data products such as elemental maps and XRF spectra from selected regions of interest. XRF spectra are processed on the ground to further determine quantitative elemental compositions. The instrument development will be presented with an emphasis on the characterization and modelling of the X-ray focussing Micro Pore Optic. An outlook on possible alternative XRF imaging applications will be discussed.

Feasibility of Raman spectroscopy in vitro after 5-ALA-based fluorescence diagnosis in the bladder

Science.gov (United States)

Grimbergen, M. C. M.; van Swol, C. F. P.; van Moorselaar, R. J. A.; Mahadevan-Jansen, A.,; Stone, N.

2006-02-01

Photodynamic diagnosis (PDD) has become popular in bladder cancer detection. Several studies have however shown an increased false positive biopsies rate under PDD guidance compared to conventional cystoscopy. Raman spectroscopy is an optical technique that utilizes molecular specific, inelastic scattering of light photons to interrogate biological tissues, which can successfully differentiate epithelial neoplasia from normal tissue and inflammations in vitro. This investigation was performed to show the feasibility of NIR Raman spectroscopy in vitro on biopsies obtained under guidance of 5-ALA induced PPIX fluorescence imaging. Raman spectra of a PPIX solution was measured to obtain a characteristic signature for the photosensitzer without contributions from tissue constituents. Biopsies were obtained from patients with known bladder cancer instilled with 50ml, 5mg 5-ALA two hours prior to trans-urethral resection of tumor (TURT). Additional biopsies were obtained at a fluorescent and non-fluorescent area, snap-frozen in liquid nitrogen and stored at -80 °C. Each biopsy was thawed before measurements (10sec integration time) with a confocal Raman system (Renishaw Gloucestershire, UK). The 830 nm excitation (300mW) source is focused on the tissue by a 20X ultra-long-working-distance objective. Differences in fluorescence background between the two groups were removed by means of a special developed fluorescence subtraction algorithm. Raman spectra from ALA biopsies showed different fluorescence background which can be effectively removed by a fluorescence subtraction algorithm. This investigation shows that the interaction of the ALA induced PPIX with Raman spectroscopy in bladder samples. Combination of these techniques in-vivo may lead to a viable method of optical biopsies in bladder cancer detection.

Instrument for fluorescence sensing of circulating cells with diffuse light in mice in vivo.

Science.gov (United States)

Zettergren, Eric; Vickers, Dwayne; Runnels, Judith; Murthy, Shashi K; Lin, Charles P; Niedre, Mark

2012-03-01

Accurate quantification of circulating cell populations in mice is important in many areas of preclinical biomedical research. Normally, this is done either by extraction and analysis of small blood samples or, more recently, by using microscopy-based in vivo fluorescence flow cytometry. We describe a new technological approach to this problem using detection of diffuse fluorescent light from relatively large blood vessels in vivo. The diffuse fluorescence flow cytometer (DFFC) uses a laser to illuminate a mouse limb and an array of optical fibers coupled to a high-sensitivity photomultiplier tube array operating in photon counting mode to detect weak fluorescence signals from cells. We first demonstrate that the DFFC instrument is capable of detecting fluorescent microspheres and Vybrant-DiD-labeled cells in a custom-made optical flow phantom with similar size, optical properties, linear flow rates, and autofluorescence as a mouse limb. We also present preliminary data demonstrating that the DFFC is capable of detecting circulating cells in nude mice in vivo. In principle, this device would allow interrogation of the whole blood volume of a mouse in minutes, with sensitivity improvement by several orders of magnitude compared to current approaches. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE).

Three-dimensional fluorescent microscopy via simultaneous illumination and detection at multiple planes.

Science.gov (United States)

Ma, Qian; Khademhosseinieh, Bahar; Huang, Eric; Qian, Haoliang; Bakowski, Malina A; Troemel, Emily R; Liu, Zhaowei

2016-08-16

The conventional optical microscope is an inherently two-dimensional (2D) imaging tool. The objective lens, eyepiece and image sensor are all designed to capture light emitted from a 2D 'object plane'. Existing technologies, such as confocal or light sheet fluorescence microscopy have to utilize mechanical scanning, a time-multiplexing process, to capture a 3D image. In this paper, we present a 3D optical microscopy method based upon simultaneously illuminating and detecting multiple focal planes. This is implemented by adding two diffractive optical elements to modify the illumination and detection optics. We demonstrate that the image quality of this technique is comparable to conventional light sheet fluorescent microscopy with the advantage of the simultaneous imaging of multiple axial planes and reduced number of scans required to image the whole sample volume.

Project Title: Radiochemical Analysis by High Sensitivity Dual-Optic Micro X-ray Fluorescence

International Nuclear Information System (INIS)

Havrilla, George J.; Gao, Ning

2002-01-01

A novel dual-optic micro X-ray fluorescence instrument will be developed to do radiochemical analysis of high-level radioactive wastes at DOE sites such as Savannah River Site and Hanford. This concept incorporates new X-ray optical elements such as monolithic polycapillaries and double bent crystals, which focus X-rays. The polycapillary optic can be used to focus X-rays emitted by the X-ray tube thereby increasing the X-ray flux on the sample over 1000 times. Polycapillaries will also be used to collect the X-rays from the excitation site and screen the radiation background from the radioactive species in the specimen. This dual-optic approach significantly reduces the background and increases the analyte signal thereby increasing the sensitivity of the analysis. A doubly bent crystal used as the focusing optic produces focused monochromatic X-ray excitation, which eliminates the bremsstrahlung background from the X-ray source. The coupling of the doubly bent crystal for monochromatic excitation with a polycapillary for signal collection can effectively eliminate the noise background and radiation background from the specimen. The integration of these X-ray optics increases the signal-to-noise and thereby increases the sensitivity of the analysis for low-level analytes. This work will address a key need for radiochemical analysis of high-level waste using a non-destructive, multi-element, and rapid method in a radiation environment. There is significant potential that this instrumentation could be capable of on-line analysis for process waste stream characterization at DOE sites

Design and evaluation of capillary coupled with optical fiber light-emitting diode induced fluorescence detection for capillary electrophoresis.

Science.gov (United States)

Ji, Hongyun; Li, Meng; Guo, Lihong; Yuan, Hongyan; Wang, Chunling; Xiao, Dan

2013-09-01

A new detector, capillary coupled with optical fiber LED-induced fluorescence detector (CCOF-LED-IFD, using CCOF for short), is introduced for CE. The strategy of the present work was that the optical fiber and separation capillary were, in the parallel direction, fastened in a fixation capillary with larger inner diameter. By employing larger inner diameter, the fixation capillary allowed the large diameter of the optical fiber to be inserted into it. By transmitting an enhanced excitation light through the optical fiber, the detection sensitivity was improved. The advantages of the CCOF-CE system were validated by the detection of riboflavin, and the results were compared to those obtained by the in-capillary common optical fiber LED-induced fluorescence detector (IC-COF-LED-IFD, using COF for short). The LODs of CCOF-CE and COF-CE were 0.29 nM and 11.0 nM (S/N = 3), respectively. The intraday (n = 6) repeatability and interday (n = 6) reproducibility of migration time and corresponding peak area for both types of CE were all less than 1.10 and 3.30%, respectively. The accuracy of the proposed method was judged by employing standard addition method, and recoveries obtained were in the range of 98.0-102.4%. The results indicated that the sensitivity of the proposed system was largely improved, and that its reproducibility and accuracy were satisfactory. The proposed system was successfully applied to separate and determine riboflavin in real sample. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Second and third generation voltage-sensitive fluorescent proteins for monitoring membrane potential

Directory of Open Access Journals (Sweden)

Amelie Perron

2009-06-01

Full Text Available Over the last decade, optical neuroimaging methods have been enriched by engineered biosensors derived from fluorescent protein (FP reporters fused to protein detectors that convert physiological signals into changes of intrinsic FP fluorescence. These FP-based indicators are genetically encoded, and hence targetable to specific cell populations within networks of heterologous cell types. Among this class of biosensors, the development of optical probes for membrane potential is both highly desirable and challenging. A suitable FP voltage sensor would indeed be a valuable tool for monitoring the activity of thousands of individual neurons simultaneously in a non-invasive manner. Previous prototypic genetically-encoded FP voltage indicators achieved a proof of principle but also highlighted several difficulties such as poor cell surface targeting and slow kinetics. Recently, we developed a new series of FRET-based Voltage-Sensitive Fluorescent Proteins (VSFPs, referred to as VSFP2s, with efficient targeting to the plasma membrane and high responsiveness to membrane potential signaling in excitable cells. In addition to these FRET-based voltage sensors, we also generated a third series of probes consisting of single FPs with response kinetics suitable for the optical imaging of fast neuronal signals. These newly available genetically-encoded reporters for membrane potential will be instrumental for future experimental approaches directed toward the understanding of neuronal network dynamics and information processing in the brain. Here, we review the development and current status of these novel fluorescent probes.

Biological applications of near-field scanning optical microscopy

NARCIS (Netherlands)

Moers, M.H.P.; Moers, Marco H.P.; Ruiter, A.G.T.; Jalocha, A.; Jalocha, Alain; van Hulst, N.F.

1995-01-01

Near-field Scanning Optical Microscopy (NSOM) is a true optical microscopic technique allowing fluorescence, absorption, reflection and polarization contrast with the additional advantage of nanometer lateral resolution, unlimited by diffraction and operation at ambient conditions. NSOM based on

New radiological material detection technologies for nuclear forensics: Remote optical imaging and graphene-based sensors.

Energy Technology Data Exchange (ETDEWEB)

Harrison, Richard Karl [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Martin, Jeffrey B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wiemann, Dora K. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Choi, Junoh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2015-09-01

We developed new detector technologies to identify the presence of radioactive materials for nuclear forensics applications. First, we investigated an optical radiation detection technique based on imaging nitrogen fluorescence excited by ionizing radiation. We demonstrated optical detection in air under indoor and outdoor conditions for alpha particles and gamma radiation at distances up to 75 meters. We also contributed to the development of next generation systems and concepts that could enable remote detection at distances greater than 1 km, and originated a concept that could enable daytime operation of the technique. A second area of research was the development of room-temperature graphene-based sensors for radiation detection and measurement. In this project, we observed tunable optical and charged particle detection, and developed improved devices. With further development, the advancements described in this report could enable new capabilities for nuclear forensics applications.

Analysis of a photon number resolving detector based on fluorescence readout of an ion Coulomb crystal quantum memory inside an optical cavity

DEFF Research Database (Denmark)

Clausen, Christoph; Sangouard, N.; Drewsen, M.

2013-01-01

The ability to detect single photons with a high efficiency is a crucial requirement for various quantum information applications. By combining the storage process of a quantum memory for photons with fluorescence-based quantum state measurement, it is, in principle, possible to achieve high......-efficiency photon counting in large ensembles of atoms. The large number of atoms can, however, pose significant problems in terms of noise stemming from imperfect initial state preparation and off-resonant fluorescence. We identify and analyse a concrete implementation of a photon number resolving detector based...... larger than 93%. Moderate experimental parameters allow for repetition rates of about 3 kHz, limited by the time needed for fluorescence collection and re-cooling of the ions between trials. Our analysis may lead to the first implementation of a photon number resolving detector in atomic ensembles....

Fluorescence lifetime measurements to determine the core-shell nanostructure of FITC-doped silica nanoparticles: An optical approach to evaluate nanoparticle photostability

International Nuclear Information System (INIS)

Santra, Swadeshmukul; Liesenfeld, Bernd; Bertolino, Chiara; Dutta, Debamitra; Cao Zehui; Tan Weihong; Moudgil, Brij M.; Mericle, Robert A.

2006-01-01

In this paper, we described a novel fluorescence lifetime-based approach to determine the core-shell nanostructure of FITC-(fluorescein isothiocyanate, isomer I) doped fluorescent silica nanoparticles (FSNPs). Because of phase homogeneity between the core and the shell, electron microscopic technique could not be used to characterize such core-shell nanostructure. Our optical approach not only revealed the core-shell nanostructure of FSNPs but also evaluated photobleaching of FSNPs both in the solvated and non-solvated (dry) states. The FSNPs were produced via Stoeber's method by hydrolysis and co-condensation reaction of tetraethylorthosilicate (TEOS) and fluorescein linked (3-aminopropyl)triethoxysilane (FITC-APTS conjugate) in the presence of ammonium hydroxide catalyst. To obtain a pure silica surface coating, FSNPs were then post-coated with TEOS. The average particle size was 135 nm as determined by TEM (transmission electron microscope) measurements. Fluorescence excitation and emission spectral data demonstrated successful doping of FITC dye molecules in FSNPs. Fluorescence lifetime data revealed that approximately 62% of dye molecules remained in the solvated silica shell, while 38% of dye molecules remained in the non-solvated (dry) silica core. Photobleaching experiments of FSNPs were conducted both in DI water (solution state) and in air (dry state). Severe photobleaching of FSNPs was observed in air. However, FSNPs were moderately photostable in the solution state. Photostability of FSNPs in both solution and dry states was explained on the basis of fluorescence lifetime data

ONIOM Investigation of the Second-Order Nonlinear Optical Responses of Fluorescent Proteins.

Science.gov (United States)

de Wergifosse, Marc; Botek, Edith; De Meulenaere, Evelien; Clays, Koen; Champagne, Benoît

2018-05-17

The first hyperpolarizability (β) of six fluorescent proteins (FPs), namely, enhanced green fluorescent protein, enhanced yellow fluorescent protein, SHardonnay, ZsYellow, DsRed, and mCherry, has been calculated to unravel the structure-property relationships on their second-order nonlinear optical properties, owing to their potential for multidimensional biomedical imaging. The ONIOM scheme has been employed and several of its refinements have been addressed to incorporate efficiently the effects of the microenvironment on the nonlinear optical responses of the FP chromophore that is embedded in a protective β-barrel protein cage. In the ONIOM scheme, the system is decomposed into several layers (here two) treated at different levels of approximation (method1/method2), from the most elaborated method (method1) for its core (called the high layer) to the most approximate one (method2) for the outer surrounding (called the low layer). We observe that a small high layer can already account for the variations of β as a function of the nature of the FP, provided the low layer is treated at an ab initio level to describe properly the effects of key H-bonds. Then, for semiquantitative reproduction of the experimental values obtained from hyper-Rayleigh scattering experiments, it is necessary to incorporate electron correlation as described at the second-order Møller-Plesset perturbation theory (MP2) level as well as implicit solvent effects accounted for using the polarizable continuum model (PCM). This led us to define the MP2/6-31+G(d):HF/6-31+G(d)/IEFPCM scheme as an efficient ONIOM approach and the MP2/6-31+G(d):HF/6-31G(d)/IEFPCM as a better compromise between accuracy and computational needs. Using these methods, we demonstrate that many parameters play a role on the β response of FPs, including the length of the π-conjugated segment, the variation of the bond length alternation, and the presence of π-stacking interactions. Then, noticing the small diversity

Novel biosensor system model based on fluorescence quenching by a fluorescent streptavidin and carbazole-labeled biotin.

Science.gov (United States)

Zhu, Xianwei; Shinohara, Hiroaki; Miyatake, Ryuta; Hohsaka, Takahiro

2016-10-01

In the present study, a novel molecular biosensor system model was designed by using a couple of the fluorescent unnatural mutant streptavidin and the carbazole-labeled biotin. BODIPY-FL-aminophenylalanine (BFLAF), a fluorescent unnatural amino acid was position-specifically incorporated into Trp120 position of streptavidin by four-base codon method. On the other hand, carbazole-labeled biotin was synthesized as a quencher for the fluorescent Trp120BFLAF mutant streptavidin. The fluorescence of fluorescent Trp120BFLAF mutant streptavidin was decreased as we expected when carbazole-labeled biotin was added into the mutant streptavidin solution. Furthermore, the fluorescence decrease of Trp120BFLAF mutant streptavidin with carbazole-labeled biotin (100 nM) was recovered by the competitive addition of natural biotin. This result demonstrated that by measuring the fluorescence quenching and recovery, a couple of the fluorescent Trp120BFLAF mutant streptavidin and the carbazole-labeled biotin were successfully applicable for quantification of free biotin as a molecular biosensor system. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Note: Tormenta: An open source Python-powered control software for camera based optical microscopy.

Science.gov (United States)

Barabas, Federico M; Masullo, Luciano A; Stefani, Fernando D

2016-12-01

Until recently, PC control and synchronization of scientific instruments was only possible through closed-source expensive frameworks like National Instruments' LabVIEW. Nowadays, efficient cost-free alternatives are available in the context of a continuously growing community of open-source software developers. Here, we report on Tormenta, a modular open-source software for the control of camera-based optical microscopes. Tormenta is built on Python, works on multiple operating systems, and includes some key features for fluorescence nanoscopy based on single molecule localization.

Real-time label-free quantitative fluorescence microscopy-based detection of ATP using a tunable fluorescent nano-aptasensor platform

Science.gov (United States)

Shrivastava, Sajal; Sohn, Il-Yung; Son, Young-Min; Lee, Won-Il; Lee, Nae-Eung

2015-11-01

Although real-time label-free fluorescent aptasensors based on nanomaterials are increasingly recognized as a useful strategy for the detection of target biomolecules with high fidelity, the lack of an imaging-based quantitative measurement platform limits their implementation with biological samples. Here we introduce an ensemble strategy for a real-time label-free fluorescent graphene (Gr) aptasensor platform. This platform employs aptamer length-dependent tunability, thus enabling the reagentless quantitative detection of biomolecules through computational processing coupled with real-time fluorescence imaging data. We demonstrate that this strategy effectively delivers dose-dependent quantitative readouts of adenosine triphosphate (ATP) concentration on chemical vapor deposited (CVD) Gr and reduced graphene oxide (rGO) surfaces, thereby providing cytotoxicity assessment. Compared with conventional fluorescence spectrometry methods, our highly efficient, universally applicable, and rational approach will facilitate broader implementation of imaging-based biosensing platforms for the quantitative evaluation of a range of target molecules.Although real-time label-free fluorescent aptasensors based on nanomaterials are increasingly recognized as a useful strategy for the detection of target biomolecules with high fidelity, the lack of an imaging-based quantitative measurement platform limits their implementation with biological samples. Here we introduce an ensemble strategy for a real-time label-free fluorescent graphene (Gr) aptasensor platform. This platform employs aptamer length-dependent tunability, thus enabling the reagentless quantitative detection of biomolecules through computational processing coupled with real-time fluorescence imaging data. We demonstrate that this strategy effectively delivers dose-dependent quantitative readouts of adenosine triphosphate (ATP) concentration on chemical vapor deposited (CVD) Gr and reduced graphene oxide (r

Developing a New Biophysical Tool to Combine Magneto-Optical Tweezers with Super-Resolution Fluorescence Microscopy

Directory of Open Access Journals (Sweden)

Zhaokun Zhou

2015-06-01

Full Text Available We present a novel experimental setup in which magnetic and optical tweezers are combined for torque and force transduction onto single filamentous molecules in a transverse configuration to allow simultaneous mechanical measurement and manipulation. Previously we have developed a super-resolution imaging module which, in conjunction with advanced imaging techniques such as Blinking assisted Localisation Microscopy (BaLM, achieves localisation precision of single fluorescent dye molecules bound to DNA of ~30 nm along the contour of the molecule; our work here describes developments in producing a system which combines tweezing and super-resolution fluorescence imaging. The instrument also features an acousto-optic deflector that temporally divides the laser beam to form multiple traps for high throughput statistics collection. Our motivation for developing the new tool is to enable direct observation of detailed molecular topological transformation and protein binding event localisation in a stretching/twisting mechanical assay that previously could hitherto only be deduced indirectly from the end-to-end length variation of DNA. Our approach is simple and robust enough for reproduction in the lab without the requirement of precise hardware engineering, yet is capable of unveiling the elastic and dynamic properties of filamentous molecules that have been hidden using traditional tools.

Enhancing cell and gene therapy manufacture through the application of advanced fluorescent optical sensors (Review).

Science.gov (United States)

Harrison, Richard P; Chauhan, Veeren M

2017-12-15

Cell and gene therapies (CGTs) are examples of future therapeutics that can be used to cure or alleviate the symptoms of disease, by repairing damaged tissue or reprogramming defective genetic information. However, despite the recent advancements in clinical trial outcomes, the path to wide-scale adoption of CGTs remains challenging, such that the emergence of a "blockbuster" therapy has so far proved elusive. Manufacturing solutions for these therapies require the application of scalable and replicable cell manufacturing techniques, which differ markedly from the existing pharmaceutical incumbent. Attempts to adopt this pharmaceutical model for CGT manufacture have largely proved unsuccessful. The most significant challenges facing CGT manufacturing are process analytical testing and quality control. These procedures would greatly benefit from improved sensory technologies that allow direct measurement of critical quality attributes, such as pH, oxygen, lactate and glucose. In turn, this would make manufacturing more robust, replicable and standardized. In this review, the present-day state and prospects of CGT manufacturing are discussed. In particular, the authors highlight the role of fluorescent optical sensors, focusing on their strengths and weaknesses, for CGT manufacture. The review concludes by discussing how the integration of CGT manufacture and fluorescent optical sensors could augment future bioprocessing approaches.

Occlusal overload investigations by noninvasive technology: fluorescence microscopy and en-face optical coherence tomography

Science.gov (United States)

Marcauteanu, Corina; Negrutiu, Meda; Sinescu, Cosmin; Demjan, Enikö; Hughes, Michael; Bradu, Adrian; Dobre, George; Podoleanu, Adrian G.

2009-07-01

The aim of this study is the early detection and monitoring of occlusal overload in bruxing patients. En-Face Optical coherence tomography (eF-OCT) and fluorescence microscopy (FM) were used for the imaging of several anterior teeth extracted from patients with light active bruxism. We found a characteristic pattern of enamel cracks, that reached the tooth surface. We concluded that the combination of the en-Face OCT and FM is a promising non-invasive alternative technique for reliable monitoring of occlusal overload.

Feasibility of Optical Instruments Based on Multiaperture Optics.

Science.gov (United States)

1984-10-16

system may be configured. The optical elements may be nonimaging concentrators (light horns), the field of view (FOV) of which may be controlled by a...RD-RI58 868 FEASIBILITY OF OPTICAL INSTRUMENTS BASED ON i/I MULTIAPERTURE OPTICS (U) FLORIDA UNIV GAINESVILLE DEPT OF NUCLEAR ENGINEERING SCIENCES J D...d Subtitle) 5. TYPE OF REPORT & PERIOD COVERED ’ 0 Feasibility of Optical Instruments Based on Final Report * CD Multiaperature Optics 615/83 to 9/30

Dual-detection confocal fluorescence microscopy: fluorescence axial imaging without axial scanning.

Science.gov (United States)

Lee, Dong-Ryoung; Kim, Young-Duk; Gweon, Dae-Gab; Yoo, Hongki

2013-07-29

We propose a new method for high-speed, three-dimensional (3-D) fluorescence imaging, which we refer to as dual-detection confocal fluorescence microscopy (DDCFM). In contrast to conventional beam-scanning confocal fluorescence microscopy, where the focal spot must be scanned either optically or mechanically over a sample volume to reconstruct a 3-D image, DDCFM can obtain the depth of a fluorescent emitter without depth scanning. DDCFM comprises two photodetectors, each with a pinhole of different size, in the confocal detection system. Axial information on fluorescent emitters can be measured by the axial response curve through the ratio of intensity signals. DDCFM can rapidly acquire a 3-D fluorescent image from a single two-dimensional scan with less phototoxicity and photobleaching than confocal fluorescence microscopy because no mechanical depth scans are needed. We demonstrated the feasibility of the proposed method by phantom studies.

Micro sized implantable ball lens-based fiber optic probe design

Science.gov (United States)

Cha, Jaepyeong; Kang, Jin U.

2014-02-01

A micro sized implantable ball lens-based fiber optic probe design is described for continuous monitoring of brain activity in freely behaving mice. A prototype uses a 500-micron ball lens and a highly flexible 350-micron-diameter fiber bundle, which are enclosed by a 21G stainless steel sheath. Several types and thickness of brain tissue, consisting of fluorescent probes such as GFP, GCaMP3 calcium indicator, are used to evaluate the performance of the imaging probe. Measured working distance is approximately 400-μm, but is long enough to detect neural activities from cortical and cerebellar tissues of mice brain.

A spirobifluorene-based two-photon fluorescence probe for mercury ions and its applications in living cells

Energy Technology Data Exchange (ETDEWEB)

Xiao, Haibo, E-mail: xiaohb@shnu.edu.cn; Zhang, Yanzhen; Zhang, Wu; Li, Shaozhi; Tan, Jingjing; Han, Zhongying

2017-05-01

A novel spirobifluorene derivative SPF-TMS, which containing dithioacetal groups and triphenylamine units, was synthesized. The probing behaviors toward various metal ions were investigated via UV/Vis absorption spectra as well as one-photon fluorescence changes. The results indicated that SPF-TMS exhibits high sensitivity and selectivity for mercury ions. The detection limit was at least 8.6 × 10{sup −8}M, which is excellent comparing with other optical sensors for Hg{sup 2+}. When measured by two-photon excited fluorescence technique in THF at 800 nm, the two-photon cross-section of SPF-TMS is 272 GM. Especially, upon reaction with mercury species, SPF-TMS yielded another two-photon dye SPF-DA. Both SPF-TMS and SPF-DA emit strong two-photon induced fluorescence and can be applied in cell imaging by two-photon microscopy. - Highlights: • We report a spirobifluorene-based molecule as two-photon fluorescent probe with large two-photon cross-section. • The molecule has exclusive selectivity and sensitivity for mercury species. • The molecule has large two-photon emission changes before and after addition of Hg{sup 2+}. • Both the probe and the mercury ion-promoted reaction product can be applied in cell imaging by two-photon microscopy.

Synthesis, X-ray crystal structure and optical properties research of novel diphenyl sulfone-based bis-pyrazoline derivatives

International Nuclear Information System (INIS)

Gong Zhongliang; Zheng Liangwen; Zhao Baoxiang

2012-01-01

A series of novel bis-pyrazoline derivatives were synthesized by the reaction of chalcone and (sulfonylbis(3,1-phenylene))bis(hydrazine) in 20–34% yields. The structures of the compounds were determined by IR, 1 H NMR, HRMS spectra, and a representative compound 3b was confirmed based on the X-ray crystallographic analysis. Absorption and fluorescence spectra of these compounds in dichloromethane solution were investigated. The results showed that the emission maxima varied from 415 to 444 nm mainly depending on C3 substituents of pyrazoline moiety. The compounds had higher quantum yields, when C3 substituent was an electron-withdrawing p-chlorophenyl group. Moreover, absorption spectra and emission spectra exhibited a blue-shift and a red-shift with increasing the polarity of solvents, respectively. Fluorescent molecules happened to collide with each other and resulted in quench of the fluorescence when the concentration increased over to 10 −5 M. - Highlights: ► A series of novel diphenyl sulfone-based bis-pyrazoline derivatives were designed and synthesized. ► Their UV–vis absorption and fluorescence emission spectra were investigated. ► The relationship of substituents and the optical properties were discussed. ► With increasing the solvent polarity, fluorescence emission displayed a red-shift and fluorescence quantum yields decreased. ► Fluorescence was quenched when the concentration increased over to 10 −5 M.

Pado, a fluorescent protein with proton channel activity can optically monitor membrane potential, intracellular pH, and map gap junctions.

Science.gov (United States)

Kang, Bok Eum; Baker, Bradley J

2016-04-04

An in silico search strategy was developed to identify potential voltage-sensing domains (VSD) for the development of genetically encoded voltage indicators (GEVIs). Using a conserved charge distribution in the S2 α-helix, a single in silico search yielded most voltage-sensing proteins including voltage-gated potassium channels, voltage-gated calcium channels, voltage-gated sodium channels, voltage-gated proton channels, and voltage-sensing phosphatases from organisms ranging from mammals to bacteria and plants. A GEVI utilizing the VSD from a voltage-gated proton channel identified from that search was able to optically report changes in membrane potential. In addition this sensor was capable of manipulating the internal pH while simultaneously reporting that change optically since it maintains the voltage-gated proton channel activity of the VSD. Biophysical characterization of this GEVI, Pado, demonstrated that the voltage-dependent signal was distinct from the pH-dependent signal and was dependent on the movement of the S4 α-helix. Further investigation into the mechanism of the voltage-dependent optical signal revealed that inhibiting the dimerization of the fluorescent protein greatly reduced the optical signal. Dimerization of the FP thereby enabled the movement of the S4 α-helix to mediate a fluorescent response.

Optical Biosensors Based on Semiconductor Nanostructures

Directory of Open Access Journals (Sweden)

Raúl J. Martín-Palma

2009-06-01

Full Text Available The increasing availability of semiconductor-based nanostructures with novel and unique properties has sparked widespread interest in their use in the field of biosensing. The precise control over the size, shape and composition of these nanostructures leads to the accurate control of their physico-chemical properties and overall behavior. Furthermore, modifications can be made to the nanostructures to better suit their integration with biological systems, leading to such interesting properties as enhanced aqueous solubility, biocompatibility or bio-recognition. In the present work, the most significant applications of semiconductor nanostructures in the field of optical biosensing will be reviewed. In particular, the use of quantum dots as fluorescent bioprobes, which is the most widely used application, will be discussed. In addition, the use of some other nanometric structures in the field of biosensing, including porous semiconductors and photonic crystals, will be presented.

Synthesis, spectral and third-order nonlinear optical properties of terpyridine Zn(II) complexes based on carbazole derivative with polyether group

Science.gov (United States)

Kong, Ming; Liu, Yanqiu; Wang, Hui; Luo, Junshan; Li, Dandan; Zhang, Shengyi; Li, Shengli; Wu, Jieying; Tian, Yupeng

2015-01-01

Four novel Zn(II) terpyridine complexes (ZnLCl2, ZnLBr2, ZnLI2, ZnL(SCN)2) based on carbazole derivative group were designed, synthesized and fully characterized. Their photophysical properties including absorption and one-photon excited fluorescence, two-photon absorption (TPA) and optical power limiting (OPL) were further investigated systematically and interpreted on the basis of theoretical calculations (TD-DFT). The influences of different solvents on the absorption and One-Photon Excited Fluorescence (OPEF) spectral behavior, quantum yields and the lifetime of the chromophores have been investigated in detail. The third-order nonlinear optical (NLO) properties were investigated by open/closed aperture Z-scan measurements using femtosecond pulse laser in the range from 680 to 1080 nm. These results revealed that ZnLCl2 and ZnLBr2 exhibited strong two-photon absorption and ZnLCl2 showed superior optical power limiting property.

Environmentally Sensitive Fluorescent Sensors Based on Synthetic Peptides

Directory of Open Access Journals (Sweden)

Laurence Choulier

2010-03-01

Full Text Available Biosensors allow the direct detection of molecular analytes, by associating a biological receptor with a transducer able to convert the analyte-receptor recognition event into a measurable signal. We review recent work aimed at developing synthetic fluorescent molecular sensors for a variety of analytes, based on peptidic receptors labeled with environmentally sensitive fluorophores. Fluorescent indicators based on synthetic peptides are highly interesting alternatives to protein-based sensors, since they can be synthesized chemically, are stable, and can be easily modified in a site-specific manner for fluorophore coupling and for immobilization on solid supports.

Applications of optical imaging

International Nuclear Information System (INIS)

Schellenberger, E.

2005-01-01

Optical imaging in the form of near infrared fluorescence and bioluminescence has proven useful for a wide range of applications in the field of molecular imaging. Both techniques provide a high sensitivity (in the nanomolar range), which is of particular importance for molecular imaging. Imaging with near infrared fluorescence is especially cost-effective and can be performed, in contrast to radioactivity-based methods, with fluorescence dyes that remain stable for months. The most important advantage of bioluminescence, in turn, is the lack of background signal. Although molecular imaging with these techniques is still in the experimental phase, an application of near infrared fluorescence is already foreseeable for the imaging of superficial structures. (orig.)

Determination of basic state parameters and characterization of optical, dielectric and fluorescence properties of calcium boro lactate (CaBL)

International Nuclear Information System (INIS)

Vijayalakshmi, A.; Balraj, V.

2016-01-01

This paper describes the calculation of basic solid state parameters like penn gap, plasma energy, polarizability and fermi energy for calcium boro lactate single crystal. calcium boro lactate crystals were developed by solution growth method. Single crystal diffraction studies carried out and calculated basic solid state criterion for the CaBL compound. optical nature of these compound explained by using UV-Visible spectrum. Electro-optic behaviour of the crystal explained by dielectric studies. Light emitting properties explained by fluorescence studies. (author)

Autoindicating optical properties of laccase as the base of an optical biosensor film for phenol determination

Energy Technology Data Exchange (ETDEWEB)

Sanz, J.; Marcos, S. de; Galban, J. [University of Zaragoza, Analytical Biosensors Group (GBA), Analytical Chemistry Department, Faculty of Sciences, Zaragoza (Spain)

2012-08-15

In the context of sustainable analytical chemistry, phenol has been determined through its enzymatic reaction with laccase. The method has been studied and optimized through the autoindicating optical properties of laccase both by intrinsic molecular absorption and fluorescence. The method shows a linear range from 9.79.10{sup -6} to 7.50.10{sup -4} M with a relative standard deviation of 1.07 %. The molecular absorption methodology has been implemented in a polyacrylamide film for the design of an autoindicating optical sensor. In order to increase the lifetime of the sensor, the reversibility study of the enzymatic reaction has proposed, as a novelty, the regeneration of laccase with an oxidase-type enzyme (glucose oxidase). The lifetime of the sensor film has improved from 15 to 30 measurements. The reaction mechanism has also been studied and confirmed by fluorescence and molecular absorption. The method leads to the determination of phenol in environmental samples. (orig.)

Intermolecular G-quadruplex structure-based fluorescent DNA detection system.

Science.gov (United States)

Zhou, Hui; Wu, Zai-Sheng; Shen, Guo-Li; Yu, Ru-Qin

2013-03-15

Adopting multi-donors to pair with one acceptor could improve the performance of fluorogenic detection probes. However, common dyes (e.g., fluorescein) in close proximity to each other would self-quench the fluorescence, and the fluorescence is difficult to restore. In this contribution, we constructed a novel "multi-donors-to-one acceptor" fluorescent DNA detection system by means of the intermolecular G-quadruplex (IGQ) structure-based fluorescence signal enhancement combined with the hairpin oligonucleotide. The novel IGQ-hairpin system was characterized using the p53 gene as the model target DNA. The proposed system showed an improved assay performance due to the introduction of IGQ-structure into fluorescent signaling probes, which could inhibit the background fluorescence and increase fluorescence restoration amplitude of fluoresceins upon target DNA hybridization. The proof-of-concept scheme is expected to provide new insight into the potential of G-quadruplex structure and promote the application of fluorescent oligonucleotide probes in fundamental research, diagnosis, and treatment of genetic diseases. Copyright © 2012 Elsevier B.V. All rights reserved.

A fluorescence switch based on a controllable photochromic naphthopyran group

International Nuclear Information System (INIS)

Chen Lizhen; Wang Guang; Zhao Xiancai

2011-01-01

A fluorescence switch based on photoisomerization of naphthopyran (NP) has been designed by employing 2-(pyridin-2-yl)-benzimidazole (BPI) and the naphthopyran containing two pyran rings (NP) as fluorescent dye and photochromic compound, respectively. The fluorescence switch of benzimidazole derivative can be modulated either by controlling the irradiation time of UV light or by adjusting the amount ratio of fluorescent benzimidazole derivative to photochromic naphthopyran in both solution and polymethyl methacrylate (PMMA) film. The experimental results indicated that the decrease of fluorescence intensity of benzimidazole derivative is attributed to the interaction of benzimidazole with naphthopyran. - Highlights: → Naphthopyran was first used to fabricate fluorescence switch with benzimidazole derivative. → Fluorescence intensity can be modulated by controlling the UV irradiation time. → Fluorescence intensity can be adjusted by changing the ratio of benzimidazole derivative to naphthopyran. → Decrease of fluorescence intensity is attributed to the interaction of benzimidazole derivative and naphthopyran.

Semiconductor Nanomaterials-Based Fluorescence Spectroscopic and Matrix-Assisted Laser Desorption/Ionization (MALDI Mass Spectrometric Approaches to Proteome Analysis

Directory of Open Access Journals (Sweden)

Suresh Kumar Kailasa

2013-12-01

Full Text Available Semiconductor quantum dots (QDs or nanoparticles (NPs exhibit very unusual physico-chemcial and optical properties. This review article introduces the applications of semiconductor nanomaterials (NMs in fluorescence spectroscopy and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS for biomolecule analysis. Due to their unique physico-chemical and optical properties, semiconductors NMs have created many new platforms for investigating biomolecular structures and information in modern biology. These semiconductor NMs served as effective fluorescent probes for sensing proteins and cells and acted as affinity or concentrating probes for enriching peptides, proteins and bacteria proteins prior to MALDI-MS analysis.

Microwave heating of arginine yields highly fluorescent nanoparticles

International Nuclear Information System (INIS)

Philippidis, Aggelos; Stefanakis, Dimitrios; Anglos, Demetrios; Ghanotakis, Demetrios

2013-01-01

Brightly fluorescent nanoparticles were produced via a single-step, single-precursor procedure based on microwave heating of an aqueous solution of the amino acid arginine. Key structural and optical properties of the resulting Arg nanoparticles, Arg-dots, are reported and discussed with emphasis on the pH dependence of their fluorescence emission. The surface of the Arg-dots was functionalised through coupling to folic acid, opening up ways for connecting fluorescent nanoparticles to cancer cells. The generality and versatility of the microwave heating procedure was further demonstrated by the synthesis of different types of carbon nanoparticles, such as CE-dots, that were produced by use of citric acid and ethanolamine as precursors and compared to the Arg-dots.

Highly Sensitive Ratiometric Fluorescent Sensor for Trinitrotoluene Based on the Inner Filter Effect between Gold Nanoparticles and Fluorescent Nanoparticles.

Science.gov (United States)

Lu, Hongzhi; Quan, Shuai; Xu, Shoufang

2017-11-08

In this work, we developed a simple and sensitive ratiometric fluorescent assay for sensing trinitrotoluene (TNT) based on the inner filter effect (IFE) between gold nanoparticles (AuNPs) and ratiometric fluorescent nanoparticles (RFNs), which was designed by hybridizing green emissive carbon dots (CDs) and red emissive quantum dots (QDs) into a silica sphere as a fluorophore pair. AuNPs in their dispersion state can be a powerful absorber to quench CDs, while the aggregated AuNPs can quench QDs in the IFE-based fluorescent assays as a result of complementary overlap between the absorption spectrum of AuNPs and emission spectrum of RFNs. As a result of the fact that TNT can induce the aggregation of AuNPs, with the addition of TNT, the fluorescent of QDs can be quenched, while the fluorescent of CDs would be recovered. Then, ratiometric fluorescent detection of TNT is feasible. The present IFE-based ratiometric fluorescent sensor can detect TNT ranging from 0.1 to 270 nM, with a detection limit of 0.029 nM. In addition, the developed method was successfully applied to investigate TNT in water and soil samples with satisfactory recoveries ranging from 95 to 103%, with precision below 4.5%. The simple sensing approach proposed here could improve the sensitivity of colorimetric analysis by changing the ultraviolet analysis to ratiometric fluorescent analysis and promote the development of a dual-mode detection system.

Real-time label-free quantitative fluorescence microscopy-based detection of ATP using a tunable fluorescent nano-aptasensor platform.

Science.gov (United States)

Shrivastava, Sajal; Sohn, Il-Yung; Son, Young-Min; Lee, Won-Il; Lee, Nae-Eung

2015-12-14

Although real-time label-free fluorescent aptasensors based on nanomaterials are increasingly recognized as a useful strategy for the detection of target biomolecules with high fidelity, the lack of an imaging-based quantitative measurement platform limits their implementation with biological samples. Here we introduce an ensemble strategy for a real-time label-free fluorescent graphene (Gr) aptasensor platform. This platform employs aptamer length-dependent tunability, thus enabling the reagentless quantitative detection of biomolecules through computational processing coupled with real-time fluorescence imaging data. We demonstrate that this strategy effectively delivers dose-dependent quantitative readouts of adenosine triphosphate (ATP) concentration on chemical vapor deposited (CVD) Gr and reduced graphene oxide (rGO) surfaces, thereby providing cytotoxicity assessment. Compared with conventional fluorescence spectrometry methods, our highly efficient, universally applicable, and rational approach will facilitate broader implementation of imaging-based biosensing platforms for the quantitative evaluation of a range of target molecules.

A New Theoretical Approach to Single-Molecule Fluorescence Optical Studies of RNA Dynamics

International Nuclear Information System (INIS)

Zhao Xinghai; Shan Guangcun; Bao Shuying

2011-01-01

Single-molecule fluorescence spectroscopy in condensed phases has many important chemical and biological applications. The single-molecule fluorescence measurements contain information about conformational dynamics on a vast range of time scales. Based on the data analysis protocols methodology proposed by X. Sunney Xie, the theoretical study here mainly focuses on the single-molecule studies of single RNA with interconversions among different conformational states, to with a single FRET pair attached. We obtain analytical expressions for fluorescence lifetime correlation functions that relate changes in fluorescence lifetime to the distance-dependent FRET mechanism within the context of the Smoluchowski diffusion model. The present work establishes useful guideline for the single-molecule studies of biomolecules to reveal the complicated folding dynamics of single RNA molecules at nanometer scale.

Theoretical Foundation for Electric-Dipole-Allowed Chiral-Specific Fluorescence Optical Rotary Dispersion (F-ORD) from Interfacial Assemblies.

Science.gov (United States)

Deng, Fengyuan; Ulcickas, James R W; Simpson, Garth J

2016-11-03

Fluorescence optical rotary dispersion (F-ORD) is proposed as a novel chiral-specific and interface-specific spectroscopic method. F-ORD measurements of uniaxial assemblies are predicted to be fully electric-dipole-allowed, with corresponding increases in sensitivity to chirality relative to chiral-specific measurements in isotropic assemblies that are commonly interpreted through coupling between electric and magnetic dynamic dipoles. Observations of strong chiral sensitivity in prior single-molecule fluorescence measurements of chiral interfacial molecules are in excellent qualitative agreement with the predictions of the F-ORD mechanism and challenging to otherwise explain. F-ORD may provide methods to suppress background fluorescence in studies of biological interfaces, as the detected signal requires both polar local order and interfacial chirality. In addition, the molecular-level descriptions of the mechanisms underpinning F-ORD may also potentially apply to aid in interpreting chiral-specific Raman and surface-enhanced Raman spectroscopy measurements of uniaxially oriented assemblies, opening up opportunities for chiral-specific and interface-specific vibrational spectroscopy.

Quantum sized Ag nanocluster assisted fluorescence enhancement in Tm{sup 3+}-Yb{sup 3+} doped optical fiber beyond plasmonics

Energy Technology Data Exchange (ETDEWEB)

Chattopadhyay, Rik; Haldar, Arindam; Paul, Mukul C.; Das, Shyamal; Bhadra, Shyamal K., E-mail: skbhadra@cgcri.res.in [Fiber Optics and Photonics Division, CSIR-Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Road, Kolkata 700032 (India)

2015-12-07

We report a process for enhancing fluorescence emission from conventional rare earth ions in optical fiber by metal nanocluster (MNC) in nonresonant indirect pumping. The process is completely different from formal metal enhanced fluorescence phenomenon as the MNCs are too small in size to support localized surface plasmon and the excitation wavelength is far from plasmon resonance frequency. We used an established theory of two coupled oscillators to explain the simultaneous enhancement of Ytterbium (Yb{sup 3+}) and Thulium (Tm{sup 3+}) emission by silver (Ag) NCs under nonresonant pumping in optical fiber. The fiber is pumped with a 980 nm fiber pigtailed laser diode with input power of 20–100 mW to excite the Yb{sup 3+}. Four times enhancement of Yb{sup 3+} emission of 900–1100 nm and Tm{sup 3+} upconversion emission around 474 nm, 650 nm, and 790 nm is observed in the fiber with Ag NCs.

Optical biosensors.

Science.gov (United States)

Damborský, Pavel; Švitel, Juraj; Katrlík, Jaroslav

2016-06-30

Optical biosensors represent the most common type of biosensor. Here we provide a brief classification, a description of underlying principles of operation and their bioanalytical applications. The main focus is placed on the most widely used optical biosensors which are surface plasmon resonance (SPR)-based biosensors including SPR imaging and localized SPR. In addition, other optical biosensor systems are described, such as evanescent wave fluorescence and bioluminescent optical fibre biosensors, as well as interferometric, ellipsometric and reflectometric interference spectroscopy and surface-enhanced Raman scattering biosensors. The optical biosensors discussed here allow the sensitive and selective detection of a wide range of analytes including viruses, toxins, drugs, antibodies, tumour biomarkers and tumour cells. © 2016 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Bilayered near-infrared fluorescent nanoparticles based on low molecular weight PEI for tumor-targeted in vivo imaging

Energy Technology Data Exchange (ETDEWEB)

Liu, Hao; Li, Ke [Xi’an Jiaotong University, Key Laboratory of Biomedical Information Engineering of Education Ministry, School of Life Science and Technology (China); Xu, Liang [The University of Kansas, Department of Molecular Biosciences (United States); Wu, Daocheng, E-mail: wudaocheng@mail.xjtu.edu.cn [Xi’an Jiaotong University, Key Laboratory of Biomedical Information Engineering of Education Ministry, School of Life Science and Technology (China)

2014-12-15

To improve the tumor fluorescent imaging results in vivo, bilayered nanoparticles encapsulating a lipophilic near-infrared (NIR) fluorescent dye 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotri-carbocyanine iodide (DiR) were prepared using low molecular weight stearic acid-grafted polyethyleneimine and hyaluronic acid (DiR-PgSHA nanoparticles), which were investigated as a novel NIR fluorescent nano-probe for in vivo tumor-targeted optical imaging. These nanoparticles were characterized by transmission electron microscopy (TEM), infrared (IR) spectra, UV-visual absorption, and fluorescent emission spectra. Their cytotoxicity in vitro and hepatotoxicity in vivo were tested by MTT assay and histological study, respectively. In vivo NIR fluorescence imaging of the DiR-PgSHA nanoparticles was performed using a Carestream imaging system. The DiR-PgSHA nanoparticles were sphere shaped with a diameter of approximately 50 nm according to the TEM images. The DiR-PgSHA nanoparticles had a low cytotoxicity in vitro according to the MTT assay and low hepatotoxicity in vivo as determined in histological studies. The fluorescent emission of DiR-PgSHA nanoparticles was stable in pH values of 5–9 in solution, with only slight blue-shifts of the emission maxima at the basic pH range. The DiR-PgSHA nanoparticles exhibited a substantial tumor-targeting ability in the optical imaging with the use of tumor-bearing mice. These results demonstrated that the DiR-PgSHA nanoparticle is an excellent biocompatible nano-probe for in vivo tumor-targeted NIR fluorescence imaging with a potential for clinical applications.

Bilayered near-infrared fluorescent nanoparticles based on low molecular weight PEI for tumor-targeted in vivo imaging

International Nuclear Information System (INIS)

Liu, Hao; Li, Ke; Xu, Liang; Wu, Daocheng

2014-01-01

To improve the tumor fluorescent imaging results in vivo, bilayered nanoparticles encapsulating a lipophilic near-infrared (NIR) fluorescent dye 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotri-carbocyanine iodide (DiR) were prepared using low molecular weight stearic acid-grafted polyethyleneimine and hyaluronic acid (DiR-PgSHA nanoparticles), which were investigated as a novel NIR fluorescent nano-probe for in vivo tumor-targeted optical imaging. These nanoparticles were characterized by transmission electron microscopy (TEM), infrared (IR) spectra, UV-visual absorption, and fluorescent emission spectra. Their cytotoxicity in vitro and hepatotoxicity in vivo were tested by MTT assay and histological study, respectively. In vivo NIR fluorescence imaging of the DiR-PgSHA nanoparticles was performed using a Carestream imaging system. The DiR-PgSHA nanoparticles were sphere shaped with a diameter of approximately 50 nm according to the TEM images. The DiR-PgSHA nanoparticles had a low cytotoxicity in vitro according to the MTT assay and low hepatotoxicity in vivo as determined in histological studies. The fluorescent emission of DiR-PgSHA nanoparticles was stable in pH values of 5–9 in solution, with only slight blue-shifts of the emission maxima at the basic pH range. The DiR-PgSHA nanoparticles exhibited a substantial tumor-targeting ability in the optical imaging with the use of tumor-bearing mice. These results demonstrated that the DiR-PgSHA nanoparticle is an excellent biocompatible nano-probe for in vivo tumor-targeted NIR fluorescence imaging with a potential for clinical applications

Optimizing plasmon-enhanced fluorescence with nonlocal metallic nanospheres

DEFF Research Database (Denmark)

Tserkezis, Christos; Stefanou, Nikolaos; Wubs, Martijn

, through the recent Generalized Nonlocal Optical Response (GNOR) theory, the concurrent contribution of modal shifts and nonradiative losses, together with a reduced emitter excitation rate due to the decreased field intensity, lead always to a strong reduction of fluorescence (see Fig. 1). Finally, we...... identify situations where the common, intuitive recipe of tuning the NP modes to match λem can in fact lead to strong fluorescence quenching, instead of the anticipated enhancement. Our results highlight the necessity for careful modeling and design of plasmon-field-enhancement based applications....

Multimodality optical coherence tomography and fluorescence confocal scanning laser ophthalmoscopy for image-guided feedback of intraocular injections in mouse models

Science.gov (United States)

Benavides, Oscar R.; Terrones, Benjamin D.; Leeburg, Kelsey C.; Mehanathan, Sankarathi B.; Levine, Edward M.; Tao, Yuankai K.

2018-02-01

Rodent models are robust tools for understanding human retinal disease and function because of their similarities with human physiology and anatomy and availability of genetic mutants. Optical coherence tomography (OCT) has been well-established for ophthalmic imaging in rodents and enables depth-resolved visualization of structures and image-based surrogate biomarkers of disease. Similarly, fluorescence confocal scanning laser ophthalmoscopy (cSLO) has demonstrated utility for imaging endogenous and exogenous fluorescence and scattering contrast in the mouse retina. Complementary volumetric scattering and en face fluorescence contrast from OCT and cSLO, respectively, enables cellular-resolution longitudinal imaging of changes in ophthalmic structure and function. We present a non-contact multimodal OCT+cSLO small animal imaging system with extended working distance to the pupil, which enables imaging during and after intraocular injection. While injections are routinely performed in mice to develop novel models of ophthalmic diseases and screen novel therapeutics, the location and volume delivered is not precisely controlled and difficult to reproduce. Animals were imaged using a custom-built OCT engine and scan-head combined with a modified commercial cSLO scan-head. Post-injection imaging showed structural changes associated with retinal puncture, including the injection track, a retinal elevation, and detachment of the posterior hyaloid. When combined with imagesegmentation, we believe OCT can be used to precisely identify injection locations and quantify injection volumes. Fluorescence cSLO can provide complementary contrast for either fluorescently labeled compounds or transgenic cells for improved specificity. Our non-contact OCT+cSLO system is uniquely-suited for concurrent imaging with intraocular injections, which may be used for real-time image-guided injections.

Application of fluorescence spectroscopy and imaging in the detection of a photosensitizer in photodynamic therapy

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Zang, Lixin; Zhao, Huimin; Zhang, Zhiguo; Cao, Wenwu

2017-02-01

Photodynamic therapy (PDT) is currently an advanced optical technology in medical applications. However, the application of PDT is limited by the detection of photosensitizers. This work focuses on the application of fluorescence spectroscopy and imaging in the detection of an effective photosenzitizer, hematoporphyrin monomethyl ether (HMME). Optical properties of HMME were measured and analyzed based on its absorption and fluorescence spectra. The production mechanism of its fluorescence emission was analyzed. The detection device for HMME based on fluorescence spectroscopy was designed. Ratiometric method was applied to eliminate the influence of intensity change of excitation sources, fluctuates of excitation sources and photo detectors, and background emissions. The detection limit of this device is 6 μg/L, and it was successfully applied to the diagnosis of the metabolism of HMME in the esophageal cancer cells. To overcome the limitation of the point measurement using fluorescence spectroscopy, a two-dimensional (2D) fluorescence imaging system was established. The algorithm of the 2D fluorescence imaging system is deduced according to the fluorescence ratiometric method using bandpass filters. The method of multiple pixel point addition (MPPA) was used to eliminate fluctuates of signals. Using the method of MPPA, SNR was improved by about 30 times. The detection limit of this imaging system is 1.9 μg/L. Our systems can be used in the detection of porphyrins to improve the PDT effect.

Single-walled carbon nanotubes as near-infrared optical biosensors for life sciences and biomedicine.

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Jain, Astha; Homayoun, Aida; Bannister, Christopher W; Yum, Kyungsuk

2015-03-01

Single-walled carbon nanotubes that emit photostable near-infrared fluorescence have emerged as near-infrared optical biosensors for life sciences and biomedicine. Since the discovery of their near-infrared fluorescence, researchers have engineered single-walled carbon nanotubes to function as an optical biosensor that selectively modulates its fluorescence upon binding of target molecules. Here we review the recent advances in the single-walled carbon nanotube-based optical sensing technology for life sciences and biomedicine. We discuss the structure and optical properties of single-walled carbon nanotubes, the mechanisms for molecular recognition and signal transduction in single-walled carbon nanotube complexes, and the recent development of various single-walled carbon nanotube-based optical biosensors. We also discuss the opportunities and challenges to translate this emerging technology into biomedical research and clinical use, including the biological safety of single-walled carbon nanotubes. The advances in single-walled carbon nanotube-based near-infrared optical sensing technology open up a new avenue for in vitro and in vivo biosensing with high sensitivity and high spatial resolution, beneficial for many areas of life sciences and biomedicine. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Stochastic Optical Reconstruction Microscopy (STORM).

Science.gov (United States)

Xu, Jianquan; Ma, Hongqiang; Liu, Yang

2017-07-05

Super-resolution (SR) fluorescence microscopy, a class of optical microscopy techniques at a spatial resolution below the diffraction limit, has revolutionized the way we study biology, as recognized by the Nobel Prize in Chemistry in 2014. Stochastic optical reconstruction microscopy (STORM), a widely used SR technique, is based on the principle of single molecule localization. STORM routinely achieves a spatial resolution of 20 to 30 nm, a ten-fold improvement compared to conventional optical microscopy. Among all SR techniques, STORM offers a high spatial resolution with simple optical instrumentation and standard organic fluorescent dyes, but it is also prone to image artifacts and degraded image resolution due to improper sample preparation or imaging conditions. It requires careful optimization of all three aspects-sample preparation, image acquisition, and image reconstruction-to ensure a high-quality STORM image, which will be extensively discussed in this unit. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

Imaging a Large Sample with Selective Plane Illumination Microscopy Based on Multiple Fluorescent Microsphere Tracking

Science.gov (United States)

Ryu, Inkeon; Kim, Daekeun

2018-04-01

A typical selective plane illumination microscopy (SPIM) image size is basically limited by the field of view, which is a characteristic of the objective lens. If an image larger than the imaging area of the sample is to be obtained, image stitching, which combines step-scanned images into a single panoramic image, is required. However, accurately registering the step-scanned images is very difficult because the SPIM system uses a customized sample mount where uncertainties for the translational and the rotational motions exist. In this paper, an image registration technique based on multiple fluorescent microsphere tracking is proposed in the view of quantifying the constellations and measuring the distances between at least two fluorescent microspheres embedded in the sample. Image stitching results are demonstrated for optically cleared large tissue with various staining methods. Compensation for the effect of the sample rotation that occurs during the translational motion in the sample mount is also discussed.

Theoretical Investigation of Oxazine 170 Perchlorate Doped Polymeric Optical Fiber Amplifier

Directory of Open Access Journals (Sweden)

Piotr Miluski

2017-01-01

Full Text Available Optical signal amplification in the waveguiding structure of optical fibers can be used for optical telecommunication systems and new light sources constructions. Organic dyes doped materials are interesting for new applications in polymeric optical fibers technology due to their benefits (efficient fluorescence, high absorption cross section, and easy processing. This article presents a numerical simulation of gain in poly(methyl methacrylate optical fiber doped by Oxazine 170 Perchlorate. The calculated gain characteristic for the used dye molar concentration (0.2·10-6–1.4·10-6 and pump power (1–10 kW is presented. The fabricated fluorescent polymeric optical fiber is also shown. The presented analysis can be used for optical amplifier construction based on dye-doped polymeric optical fiber (POF.

Tracer-based laser-induced fluorescence measurement technique for quantitative fuel/air-ratio measurements in a hydrogen internal combustion engine.

Science.gov (United States)

Blotevogel, Thomas; Hartmann, Matthias; Rottengruber, Hermann; Leipertz, Alfred

2008-12-10

A measurement technique for the quantitative investigation of mixture formation processes in hydrogen internal combustion engines (ICEs) has been developed using tracer-based laser-induced fluorescence (TLIF). This technique can be employed to fired and motored engine operation. The quantitative TLIF fuel/air-ratio results have been verified by means of linear Raman scattering measurements. Exemplary results of the simultaneous investigation of mixture formation and combustion obtained at an optical accessible hydrogen ICE are shown.

Fluorescent strategy based on cationic conjugated polymer fluorescence resonance energy transfer for the quantification of 5-(hydroxymethyl)cytosine in genomic DNA.

Science.gov (United States)

Hong, Tingting; Wang, Tianlu; Guo, Pu; Xing, Xiwen; Ding, Fei; Chen, Yuqi; Wu, Jinjun; Ma, Jingwei; Wu, Fan; Zhou, Xiang

2013-11-19

DNA methylation is dynamically reprogrammed during early embryonic development in mammals. It can be explained partially by the discovery of 5-(hydroxymethyl)cytosine (5-hmC), 5-formylcytosine (5-fC), and 5-carboxylcytosine (5-caC), which are identified as key players involved in both active and passive demethylation pathways. As one of the ten-eleven translocation oxidation products, 5-hmC was found relatively abundant in neuron cells and embryonic stem cells. Herein we report a new method for 5-hmC quantification in genomic DNA based on CCP-FRET (cationic conjugated polymers act as the energy donor and induce fluorescence resonance energy transfer) assay combined with KRuO4 oxidation. 5-hmC in genomic DNA can be selectively transformed into 5-fC by the oxidation of KRuO4 and then labeled with hydroxylamine-BODIPY (BODIPY = 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) fluorophore through the reaction between 5-fC and hydroxylamine-BODIPY. After the fluorescently labeled DNA was captured by CCP through electrostatic interactions, a significant FRET between CCP and hydroxylamine-BODIPY fluorophore was observed. This CCP-FRET-based assay benefits from light-harvesting, large Stokes shift, and optical signal amplification properties of the CCP. Furthermore, this CCP-FRET-based assay was quite successfully demonstrated for the 5-hmC quantification in three types of cells (mESc, HeLa, HEK 293T), providing a much more convenient choice for 5-hmC quantification in genomic DNA.

Quantum-dot based nanothermometry in optical plasmonic recording media

International Nuclear Information System (INIS)

Maestro, Laura Martinez; Zhang, Qiming; Li, Xiangping; Gu, Min; Jaque, Daniel

2014-01-01

We report on the direct experimental determination of the temperature increment caused by laser irradiation in a optical recording media constituted by a polymeric film in which gold nanorods have been incorporated. The incorporation of CdSe quantum dots in the recording media allowed for single beam thermal reading of the on-focus temperature from a simple analysis of the two-photon excited fluorescence of quantum dots. Experimental results have been compared with numerical simulations revealing an excellent agreement and opening a promising avenue for further understanding and optimization of optical writing processes and media

CdTe Quantum Dots Embedded in Multidentate Biopolymer Based on Salep: Characterization and Optical Properties

Directory of Open Access Journals (Sweden)

Ghasem Rezanejade Bardajee

2013-01-01

Full Text Available This paper describes a novel method for surface modification of water soluble CdTe quantum dots (QDs by using poly(acrylic acid grafted onto salep (salep-g-PAA as a biopolymer. As-prepared CdTe-salep-g-PAA QDs were characterized by Fourier transform infrared (FT-IR spectrum, thermogravimetric (TG analysis, and transmission electron microscopy (TEM. The absorption and fluorescence emission spectra were measured to investigate the effect of salep-g-PAA biopolymer on the optical properties of CdTe QDs. The results showed that the optical properties of CdTe QDs were significantly enhanced by using salep-g-PAA-based biopolymer.

Novel fiber optic-based needle redox imager for cancer diagnosis

Science.gov (United States)

Kanniyappan, Udayakumar; Xu, He N.; Tang, Qinggong; Gaitan, Brandon; Liu, Yi; Li, Lin Z.; Chen, Yu

2018-02-01

Despite various technological advancements in cancer diagnosis, the mortality rates were not decreased significantly. We aim to develop a novel optical imaging tool to assist cancer diagnosis effectively. Fluorescence spectroscopy/imaging is a fast, rapid, and minimally invasive technique which has been successfully applied to diagnosing cancerous cells/tissues. Recently, the ratiometric imaging of intrinsic fluorescence of reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), as pioneered by Britton Chance and the co-workers in 1950-70's, has gained much attention to quantify the physiological parameters of living cells/tissues. The redox ratio, i.e., FAD/(FAD+NADH) or FAD/NADH, has been shown to be sensitive to various metabolic changes in in vivo and in vitro cells/tissues. Optical redox imaging has also been investigated for providing potential imaging biomarkers for cancer transformation, aggressiveness, and treatment response. Towards this goal, we have designed and developed a novel fiberoptic-based needle redox imager (NRI) that can fit into an 11G clinical coaxial biopsy needle for real time imaging during clinical cancer surgery. In the present study, the device is calibrated with tissue mimicking phantoms of FAD and NADH along with various technical parameters such as sensitivity, dynamic range, linearity, and spatial resolution of the system. We also conducted preliminary imaging of tissues ex vivo for validation. We plan to test the NRI on clinical breast cancer patients. Once validated this device may provide an effective tool for clinical cancer diagnosis.

Nanomaterials-Based Optical Techniques for the Detection of Acetylcholinesterase and Pesticides

Directory of Open Access Journals (Sweden)

Ning Xia

2014-12-01

Full Text Available The large amount of pesticide residues in the environment is a threat to global health by inhibition of acetylcholinesterase (AChE. Biosensors for inhibition of AChE have been thus developed for the detection of pesticides. In line with the rapid development of nanotechnology, nanomaterials have attracted great attention and have been intensively studied in biological analysis due to their unique chemical, physical and size properties. The aim of this review is to provide insight into nanomaterial-based optical techniques for the determination of AChE and pesticides, including colorimetric and fluorescent assays and surface plasmon resonance.

A miniaturized oxygen sensor integrated on fiber surface based on evanescent-wave induced fluorescence quenching

Energy Technology Data Exchange (ETDEWEB)

Xiong, Yan [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, 610500 (China); Tan, Jun; Wang, Chengjie; Zhu, Ying [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Fang, Shenwen [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, 610500 (China); Wu, Jiayi; Wang, Qing [School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Duan, Ming, E-mail: swpua124@126.com [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500 (China); School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu 610500 (China); Oil and Gas Field Applied Chemistry Key Laboratory of Sichuan Province, Southwest Petroleum University, Chengdu, 610500 (China)

2016-11-15

In this work, a miniaturized sensor was integrated on fiber surface and developed for oxygen determination through evanescent-wave induced fluorescence quenching. The sensor was designed by using light emitting diode (LED) as light source and optical fiber as light transmission element. Tris(2,2′-bipyridyl) ruthenium ([Ru(bpy){sub 3}]{sup 2+}) fluorophore was immobilized in the organically modified silicates (ORMOSILs) film and coated onto the fiber surface. When light propagated by total internal reflection (TIR) in the fiber core, evanescent wave could be produced on the fiber surface and excite [Ru(bpy){sub 3}]{sup 2+} fluorophore to produce fluorescence emission. Then oxygen could be determinated by its quenching effect on the fluorescence and its concentration could be evaluated according to Stern–Volumer model. Through integrating evanescent wave excitation and fluorescence quenching on fiber surface, the sensor was successfully miniaturized and exhibit improved performances of high sensitivity (1.4), excellent repeatability (1.2%) and fast analysis (12 s) for oxygen determination. The sensor provided a newly portable method for in-situ and real-time measurement of oxygen and showed potential for practical oxygen analysis in different application fields. Furthermore, the fabrication of this sensor provides a miniaturized and portable detection platform for species monitoring by simple modular design. - Highlights: • ORMOSILs sensing film immobilized with [Ru(bpy){sub 3}]{sup 2+} fluorophore was coated on fiber surface. • Evanescent wave on the fiber surface was utilized as excitation source to produce fluorescence. • Oxygen was measured based on its quenching effect on evanescent wave-induce fluorescence. • Sensor fabrication was miniaturized by integrating detection and sensing elements on the fiber. • The modular design sensor provides a detection platform for other species monitoring.

340 nm pulsed UV LED system for europium-based time-resolved fluorescence detection of immunoassays

DEFF Research Database (Denmark)

Rodenko, Olga; Fodgaard, Henrik; Tidemand-Lichtenberg, Peter

2016-01-01

We report on the design, development and investigation of an optical system based on UV light emitting diode (LED) excitation at 340 nm for time-resolved fluorescence detection of immunoassays. The system was tested to measure cardiac marker Troponin I with a concentration of 200 ng....../L in immunoassay. The signal-to-noise ratio was comparable to state-of-the-art Xenon flash lamp based unit with equal excitation energy and without overdriving the LED. We performed a comparative study of the flash lamp and the LED based system and discussed temporal, spatial, and spectral features of the LED...... excitation for time-resolved fluorimetry. Optimization of the suggested key parameters of the LED promises significant increase of the signal-to-noise ratio and hence of the sensitivity of immunoassay systems....

340 nm pulsed UV LED system for europium-based time-resolved fluorescence detection of immunoassays.

Science.gov (United States)

Rodenko, Olga; Fodgaard, Henrik; Tidemand-Lichtenberg, Peter; Petersen, Paul Michael; Pedersen, Christian

2016-09-19

We report on the design, development and investigation of an optical system based on UV light emitting diode (LED) excitation at 340 nm for time-resolved fluorescence detection of immunoassays. The system was tested to measure cardiac marker Troponin I with a concentration of 200 ng/L in immunoassay. The signal-to-noise ratio was comparable to state-of-the-art Xenon flash lamp based unit with equal excitation energy and without overdriving the LED. We performed a comparative study of the flash lamp and the LED based system and discussed temporal, spatial, and spectral features of the LED excitation for time-resolved fluorimetry. Optimization of the suggested key parameters of the LED promises significant increase of the signal-to-noise ratio and hence of the sensitivity of immunoassay systems.

Fluorescence-based bioassays for the detection and evaluation of food materials.

Science.gov (United States)

Nishi, Kentaro; Isobe, Shin-Ichiro; Zhu, Yun; Kiyama, Ryoiti

2015-10-13

We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based microarrays/biochips, such as antibody/protein microarrays, bead/suspension arrays, capillary/sensor arrays, DNA microarrays/polymerase chain reaction (PCR)-based arrays, glycan/lectin arrays, immunoassay/enzyme-linked immunosorbent assay (ELISA)-based arrays, microfluidic chips and tissue arrays, have been developed and used for the assessment of allergy/poisoning/toxicity, contamination and efficacy/mechanism, and quality control/safety. DNA microarray assays have been used widely for food safety and quality as well as searches for active components. DNA microarray-based gene expression profiling may be useful for such purposes due to its advantages in the evaluation of pathway-based intracellular signaling in response to food materials.

Fluorescence-Based Bioassays for the Detection and Evaluation of Food Materials

Directory of Open Access Journals (Sweden)

Kentaro Nishi

2015-10-01

Full Text Available We summarize here the recent progress in fluorescence-based bioassays for the detection and evaluation of food materials by focusing on fluorescent dyes used in bioassays and applications of these assays for food safety, quality and efficacy. Fluorescent dyes have been used in various bioassays, such as biosensing, cell assay, energy transfer-based assay, probing, protein/immunological assay and microarray/biochip assay. Among the arrays used in microarray/biochip assay, fluorescence-based microarrays/biochips, such as antibody/protein microarrays, bead/suspension arrays, capillary/sensor arrays, DNA microarrays/polymerase chain reaction (PCR-based arrays, glycan/lectin arrays, immunoassay/enzyme-linked immunosorbent assay (ELISA-based arrays, microfluidic chips and tissue arrays, have been developed and used for the assessment of allergy/poisoning/toxicity, contamination and efficacy/mechanism, and quality control/safety. DNA microarray assays have been used widely for food safety and quality as well as searches for active components. DNA microarray-based gene expression profiling may be useful for such purposes due to its advantages in the evaluation of pathway-based intracellular signaling in response to food materials.

The optical behavior of amorphous microribbons for hydroxy-naphthol based Schiff bases

Energy Technology Data Exchange (ETDEWEB)

Shen, Ping; Liu, Chunlin; Yang, Wei; Liu, Xuan; Du, Jinya [College of Biological and Pharmaceutical Science, China Three Gorges University, Yichang 443002 (China); Liu, Yi [College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072 (China); Yang, Changying, E-mail: changying.yang@ctgu.edu.cn [College of Biological and Pharmaceutical Science, China Three Gorges University, Yichang 443002 (China)

2017-05-15

The optical behaviors of three hydroxy-naphthol based Schiff bases, L1, L2 and L3, in aggregated states in 1,4-dioxane (Diox) – H{sub 2}O mixture, were investigated. The intermolecular hydrogen bond between luminogen and water resulted in the twisting of benzothiazole group, which is favorable for the assembly of organic molecules into J-aggregates. And also a bathochromic shift in absorption and enhancement of the fluorescence emission (aggregation-induced enhanced emission, AIEE) can be observed. L1 and L2 in Diox-H{sub 2}O mixture with water volume fractions (f{sub w}) 95% assembled into microribbons with 40–50 nm thickness, twisted together to make amorphous supramolecular organogels. Whereas L3 assembled into needle-like nanorods with the thickness up to ~200 nm, consistence with its lower emission intensity compared to L1, L2 aggregates. Moreover, a drastic blue-shift and an enhancement of emission efficiency of L1-L3 were also observed in solid states with the morphology change from the crystalline to the amorphous state by grinding. It was found that L1 aggregates showed fluorescence switch-off sensing towards Cu{sup 2+}, with higher selectivity and sensitivity compared to L1 in Diox solution. - Graphical abstract: Three Schiff bases derivatives, L1, L2 and L3, consisting of hydroxy-naphthol and thiazole group, exhibited AIEE effect in Diox-H{sub 2}O mixture with f{sub w} 95% (for L1 and L2) or 99% (for L3). The formation of amorphous nanoparticles is advantageous for emission enhancement. The drastic blue-shift and an enhancement of emission efficiency were also observed in L1-L3 with the morphology change from the crystalline to the amorphous state in solid by grinding. It was found that L1 AIEE system could be constructed as a chemoprobe towards Cu{sup 2+} fluorescence recognition, with higher selectivity and sensitivity compared to L1 in Diox solution.

Nonlinear adaptive optics: aberration correction in three photon fluorescence microscopy for mouse brain imaging

Science.gov (United States)

Sinefeld, David; Paudel, Hari P.; Wang, Tianyu; Wang, Mengran; Ouzounov, Dimitre G.; Bifano, Thomas G.; Xu, Chris

2017-02-01

Multiphoton fluorescence microscopy is a well-established technique for deep-tissue imaging with subcellular resolution. Three-photon microscopy (3PM) when combined with long wavelength excitation was shown to allow deeper imaging than two-photon microscopy (2PM) in biological tissues, such as mouse brain, because out-of-focus background light can be further reduced due to the higher order nonlinear excitation. As was demonstrated in 2PM systems, imaging depth and resolution can be improved by aberration correction using adaptive optics (AO) techniques which are based on shaping the scanning beam using a spatial light modulator (SLM). In this way, it is possible to compensate for tissue low order aberration and to some extent, to compensate for tissue scattering. Here, we present a 3PM AO microscopy system for brain imaging. Soliton self-frequency shift is used to create a femtosecond source at 1675 nm and a microelectromechanical (MEMS) SLM serves as the wavefront shaping device. We perturb the 1020 segment SLM using a modified nonlinear version of three-point phase shifting interferometry. The nonlinearity of the fluorescence signal used for feedback ensures that the signal is increasing when the spot size decreases, allowing compensation of phase errors in an iterative optimization process without direct phase measurement. We compare the performance for different orders of nonlinear feedback, showing an exponential growth in signal improvement as the nonlinear order increases. We demonstrate the impact of the method by applying the 3PM AO system for in-vivo mouse brain imaging, showing improvement in signal at 1-mm depth inside the brain.

Environmental effects on underwater optical transmission

Science.gov (United States)

Chu, Peter C.; Breshears, Brian F.; Cullen, Alexander J.; Hammerer, Ross F.; Martinez, Ramon P.; Phung, Thai Q.; Margolina, Tetyana; Fan, Chenwu

2017-05-01

Optical communication/detection systems have potential to get around some limitations of current acoustic communications and detection systems especially increased fleet and port security in noisy littoral waters. Identification of environmental effects on underwater optical transmission is the key to the success of using optics for underwater communication and detection. This paper is to answer the question "What are the transfer and correlation functions that relate measurements of hydrographic to optical parameters?" Hydrographic and optical data have been collected from the Naval Oceanographic Office survey ships with the High Intake Defined Excitation (HIDEX) photometer and sea gliders with optical back scattering sensor in various Navy interested areas such as the Arabian Gulf, Gulf of Oman, east Asian marginal seas, and Adriatic Sea. The data include temperature, salinity, bioluminescence, chlorophyll-a fluorescence, transmissivity at two different wavelengths (TRed at 670 nm, TBlue at 490 nm), and back scattering coefficient (bRed at 700 nm, bBlue at 470 nm). Transfer and correlation functions between the hydrographic and optical parameters are obtained. Bioluminescence and fluorescence maxima, transmissivity minimum with their corresponding depths, red and blue laser beam peak attenuation coefficients are identified from the optical profiles. Evident correlations are found between the ocean mixed layer depth and the blue and red laser beam peak attenuation coefficients, bioluminescence and fluorescence maxima in the Adriatic Sea, Arabian Gulf, Gulf of Oman, and Philippine Sea. Based on the observational data, an effective algorithm is recommended for solving the radiative transfer equation (RTE) for predicting underwater laser radiance.

Cucurbiturils: molecular nanocapsules for time-resolved fluorescence-based assays.

Science.gov (United States)

Marquez, Cesar; Huang, Fang; Nau, Werner M

2004-03-01

A new fluorescent host-guest system based on the inclusion of the fluorophore 2,3-diazabicyclo[2.2.2]oct-2-ene (DBO) into the cavity of the molecular container compound cucurbit[7]uril (CB7) has been designed which possesses an exceedingly long-lived emission (690 ns in aerated water). The large binding constant of (4 +/- 1) x 10(5) M(-1) along with the resistance of the CB7.DBO complex toward external fluorescence quenchers allow the use of CB7 as an enhancer in time-resolved fluorescence-based assays, e.g., to screen enzyme activity or inhibition by using DBO-labeled peptides as substrates. The response of CB7.DBO to different environmental conditions and possible quenchers are described.

Spectral filtering modulation method for estimation of hemoglobin concentration and oxygenation based on a single fluorescence emission spectrum in tissue phantoms.

Science.gov (United States)

Liu, Quan; Vo-Dinh, Tuan

2009-10-01

Hemoglobin concentration and oxygenation in tissue are important biomarkers that are useful in both research and clinical diagnostics of a wide variety of diseases such as cancer. The authors aim to develop simple ratiometric method based on the spectral filtering modulation (SFM) of fluorescence spectra to estimate the total hemoglobin concentration and oxygenation in tissue using only a single fluorescence emission spectrum, which will eliminate the need of diffuse reflectance measurements and prolonged data processing as required by most current methods, thus enabling rapid clinical measurements. The proposed method consists of two steps. In the first step, the total hemoglobin concentration is determined by comparing a ratio of fluorescence intensities at two emission wavelengths to a calibration curve. The second step is to estimate oxygen saturation by comparing a double ratio that involves three emission wavelengths to another calibration curve that is a function of oxygen saturation for known total hemoglobin concentration. Theoretical derivation shows that the ratio in the first step is linearly proportional to the total hemoglobin concentrations and the double ratio in the second step is related to both total hemoglobin concentration and hemoglobin oxygenation for the chosen fiber-optic probe geometry. Experiments on synthetic fluorescent tissue phantoms, which included hemoglobin with both constant and varying oxygenation as the absorber, polystyrene spheres as scatterers, and flavin adenine dinucleotide as the fluorophore, were carried out to validate the theoretical prediction. Tissue phantom experiments confirm that the ratio in the first step is linearly proportional to the total hemoglobin concentration and the double ratio in the second step is related to both total hemoglobin concentrations and hemoglobin oxygenation. Furthermore, the relations between the two ratios and the total hemoglobin concentration and hemoglobin oxygenation are insensitive

Clinical multi-colour fluorescence imaging of malignant tumours - initial experience

International Nuclear Information System (INIS)

Svanberg, K.; Wang, I.; Montan, S.; Andersson-Engels, S.; Svanberg, S.; Lund Inst. of Technology

1998-01-01

The purpose of this study was to present a new technique for non-invasive tumour detection based on tissue fluorescence imaging. A clinically adapted multi-colour fluorescence system was employed in the real-time imaging of malignant tumours of the skin, breast, head and neck region, and urinary bladder. Tumour detection was based on the contrast displayed in fluorescence between normal and malignant tissue, related to the selective uptake of tumour-marking agents and natural chromophore differences between various tissues. In order to demarcate basal cell carcinomas of the skin, ALA was applied topically 4-6 h before the fluorescence investigation. For urinary bladder tumour visualisation, ALA was instilled into the bladder 1-2 h prior to the study. Malignant and premalignant lesions in the head and neck region were imaged after i.v. injection of HPD (Photofrin). The tumour imaging system was coupled to an endoscope. Fluorescence light emission from the tissue surface was induced with 100-ns-long optical pulses at 390 nm, generated from a frequency-doubled alexandrite laser. With the use of special image-splitting optics, the tumour fluorescence, intensified in a micro-channel plate, was imaged in 3 selected wavelength bands. These 3 images were processed together to form a new optimised-contrast image of the tumour. This image, updated at a rate of about 3 frames/s was mixed with a normal colour video image of the tissue. A clear demarcation from normal surrounding tissue was found during in vivo measurements of superficial bladder carcinoma, basal cell carcinoma of the skin, and leukoplakia with dysplasia of the lip, and in vitro investigations of resected breast cancer. (orig./MG)

Combinatorial mutagenesis of the voltage-sensing domain enables the optical resolution of action potentials firing at 60 Hz by a genetically encoded fluorescent sensor of membrane potential.

Science.gov (United States)

Piao, Hong Hua; Rajakumar, Dhanarajan; Kang, Bok Eum; Kim, Eun Ha; Baker, Bradley J

2015-01-07

ArcLight is a genetically encoded fluorescent voltage sensor using the voltage-sensing domain of the voltage-sensing phosphatase from Ciona intestinalis that gives a large but slow-responding optical signal in response to changes in membrane potential (Jin et al., 2012). Fluorescent voltage sensors using the voltage-sensing domain from other species give faster yet weaker optical signals (Baker et al., 2012; Han et al., 2013). Sequence alignment of voltage-sensing phosphatases from different species revealed conserved polar and charged residues at 7 aa intervals in the S1-S3 transmembrane segments of the voltage-sensing domain, suggesting potential coil-coil interactions. The contribution of these residues to the voltage-induced optical signal was tested using a cassette mutagenesis screen by flanking each transmembrane segment with unique restriction sites to allow for the testing of individual mutations in each transmembrane segment, as well as combinations in all four transmembrane segments. Addition of a counter charge in S2 improved the kinetics of the optical response. A double mutation in the S4 domain dramatically reduced the slow component of the optical signal seen in ArcLight. Combining that double S4 mutant with the mutation in the S2 domain yielded a probe with kinetics voltage-sensing domain could potentially lead to fluorescent sensors capable of optically resolving neuronal inhibition and subthreshold synaptic activity. Copyright © 2015 the authors 0270-6474/15/350372-15$15.00/0.

Oxygen sensitive polymeric nanocapsules for optical dissolved oxygen sensors

Science.gov (United States)

Sun, Zhijuan; Cai, Chenxin; Guo, Fei; Ye, Changhuai; Luo, Yingwu; Ye, Shuming; Luo, Jianchao; Zhu, Fan; Jiang, Chunyue

2018-04-01

Immobilization of the oxygen-sensitive probes (OSPs) in the host matrix greatly impacts the performance and long-term usage of the optical dissolved oxygen (DO) sensors. In this work, fluorescent dyes, as the OSPs, were encapsulated with a crosslinked fluorinated polymer shell by interfacial confined reversible addition fragmentation chain transfer miniemulsion polymerization to fabricate oxygen sensitive polymeric nanocapsules (NCs). The location of fluorescent dyes and the fluorescent properties of the NCs were fully characterized by fourier transform infrared spectrometer, x-ray photoelectron spectrometer and fluorescent spectrum. Dye-encapsulated capacity can be precisely tuned from 0 to 1.3 wt% without self-quenching of the fluorescent dye. The crosslinked fluorinated polymer shell is not only extremely high gas permeability, but also prevents the fluorescent dyes from leakage in aqueous as well as in various organic solvents, such as ethanol, acetone and tetrahydrofuran (THF). An optical DO sensor based on the oxygen sensitive NCs was fabricated, showing high sensitivity, short response time, full reversibility, and long-term operational stability of online monitoring DO. The sensitivity of the optical DO sensor is 7.02 (the ratio of the response value in fully deoxygenated and saturated oxygenated water) in the range 0.96-14.16 mg l-1 and the response time is about 14.3 s. The sensor’s work curve was fit well using the modified Stern-Volmer equation by two-site model, and its response values are hardly affected by pH ranging from 2 to 12 and keep constant during continuous measurement for 3 months. It is believed that the oxygen sensitive polymeric NCs-based optical DO sensor could be particularly useful in long-term online DO monitoring in both aqueous and organic solvent systems.

Thermal lens study of thermo-optical properties and concentration quenching of Er3+-doped lead pyrophosphate based glasses

Energy Technology Data Exchange (ETDEWEB)

Santos, C. C. [Universidade Federal do Ceara, Ceara, Brazil; Rocha, U. [Grupo de Fotônica e Fluidos Complexos, Instituto de Física, Brazil; Guedes, Ilde [Universidade Federal do Ceara, Ceara, Brazil; Vermelho, M. V. D. [Instituto de Fisica, Universidade Federal de Alagoas, Brazil; Boatner, Lynn A [ORNL; Jacinto, C. [Instituto de Fisica, Universidade Federal de Alagoas, Brazil

2012-01-01

In this work, we have used the thermal lens technique combined with conventional spectroscopy to characterize the thermo-optical properties of Er3+-doped lead pyrophosphate-based glasses. More precisely, we have investigated and quantified experimentally the fluorescence quantum efficiencies of the Er3+ levels, and we describe the role of concentration quenching effects. The fluorescence quantum efficiency of the 4I13/2 level is very high when compared to other phosphate glasses, while that of the green-coupled levels is very small. Other important photonic materials parameters, such as the thermal diffusivity and temperature coefficient of the optical path length change, were obtained and compared with those of other glass systems. The cumulative results obtained here for the Er-doped lead pyrophosphate glass show that this material is a good candidate for photonic applications with a characteristic Er3+ infrared emission around 1550 nm.

Spectroscopic Analysis of Red Fluorescent Proteins and Development of a Microfluidic Cell Sorter for the Generation of Improved Variants

Science.gov (United States)

Lubbeck, Jennifer L.

The discovery of the green fluorescent protein (GFP) launched the development of a wide variety of fluorescent protein (FP) mutants whose spectral and photophysical diversity revolutionized in vivo imaging. The excitation and emission spectra of red fluorescent proteins (RFPs), in particular, have been ideally tuned to a window optically favorable for in vivo work. However, their quantum yields, photostabilities and fluorescence intermittency properties require improvement if they are to be broadly employed for low-copy or single-molecule measurements. Attempts to engineer improved RFPs often result in optimization of one photophysical property at the expense of others. We developed a microfluidic-based cytometer for screening HeLa cell-based genetic RFP-libraries simultaneously on the basis of fluorescence lifetime (a proxy for quantum yield), photostability, and brightness. Ten 532 nm excitation beams interrogate each cell in flow. The first is electro-optically modulated (30 MHz) to enable lifetime measurement with phase fluorimetry. The remaining beams act as a pulse sequence for isolating the irreversible photobleaching time constant. Optical-force switching is employed to sort cells based on any combination of the photophysical parameters. Screening with this instrument enables identification of regions of the structure that synergistically affect quantum yield and photostability and the sorting capability provides a new tool for accelerating the development of next generation RFPs.

Side Effect of Good's Buffers on Optical Properties of Gold Nanoparticle Solutions

DEFF Research Database (Denmark)

Engelbrekt, Christian; Wagner, Michal; Undall-Behrend Christiansen, Mikkel

2016-01-01

spectroscopy. Distinct absorption features at ca. 290 and 360 nm and fluorescence emission in the 408-484 nm range are observed in filtered AuNP-free solutions. Electrochemical oxidation of these buffers generates similar optical properties, suggesting that the degradation products of the buffers contribute...... to the optical properties of AuNP solutions. This work indicates deeper evaluation of fluorescence signals based on metal NPs or NCs is needed....

Evaluation of a fluorescence-based method for antibabesial drug screening.

Science.gov (United States)

Guswanto, Azirwan; Sivakumar, Thillaiampalam; Rizk, Mohamed Abdo; Elsayed, Shimaa Abd Elsalam; Youssef, Mohamed Ahmed; ElSaid, ElSaid El Shirbini; Yokoyama, Naoaki; Igarashi, Ikuo

2014-08-01

In vitro evaluation of chemotherapeutic agents against Babesia and Theileria parasites has become routine, and the effectiveness of these chemicals is usually determined by comparing the parasitemia dynamics of untreated and treated parasites. Although microscopy is widely used to calculate parasitemia, several disadvantages are associated with this technique. The present study evaluated a fluorescence-based method using SYBR green I stain (SG I) to screen antibabesial agents in in vitro cultures of Babesia bovis. The linearity between relative fluorescence units (RFU) and parasitemia was found to be well correlated with a 0.9944 goodness-of-fit (r(2)) value. Subsequently, 50% inhibitory concentration (IC50) values were calculated for 3 antiprotozoan agents, diminazene aceturate, nimbolide, and gedunin, by this method. For diminazene aceturate and nimbolide, the IC(50)s determined by the fluorescence-based method (408 nM and 8.13 μM, respectively) and microscopy (400.3 nM and 9.4 μM, respectively) were in agreement. Furthermore, the IC50 of gedunin determined by the fluorescence-based method (19 μM) was similar to the recently described microscopy-based value (21.7 μM) for B. bovis. Additionally, the Z' factor (0.80 to 0.90), signal-to-noise (S/N) ratio (44.15 to 87.64), coefficient of variation at the maximum signal (%CVmax) (0.50 to 2.85), and coefficient of variation at the minimum signal (%CVmin) (1.23 to 2.21) calculated for the fluorescence method using diminazene aceturate were comparable to those previously determined in malaria research for this assay. These findings suggest that the fluorescence-based method might be useful for antibabesial drug screening and may have potential to be developed into a high-throughput screening (HTS) assay. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Diode-Laser Induced Fluorescence Spectroscopy of an Optically Thick Plasma in Combination with Laser Absorption Spectroscopy

Directory of Open Access Journals (Sweden)

S. Nomura

2013-01-01

Full Text Available Distortion of laser-induced fluorescence profiles attributable to optical absorption and saturation broadening was corrected in combination with laser absorption spectroscopy in argon plasma flow. At high probe-laser intensity, saturated absorption profiles were measured to correct probe-laser absorption. At low laser intensity, nonsaturated absorption profiles were measured to correct fluorescence reabsorption. Saturation broadening at the measurement point was corrected using a ratio of saturated to non-saturated broadening. Observed LIF broadening and corresponding translational temperature without correction were, respectively, 2.20±0.05 GHz and 2510±100 K and corrected broadening and temperature were, respectively, 1.96±0.07 GHz and 1990±150 K. Although this correction is applicable only at the center of symmetry, the deduced temperature agreed well with that obtained by LAS with Abel inversion.

Wireless implantable electronic platform for chronic fluorescent-based biosensors.

Science.gov (United States)

Valdastri, Pietro; Susilo, Ekawahyu; Förster, Thilo; Strohhöfer, Christof; Menciassi, Arianna; Dario, Paolo

2011-06-01

The development of a long-term wireless implantable biosensor based on fluorescence intensity measurement poses a number of technical challenges, ranging from biocompatibility to sensor stability over time. One of these challenges is the design of a power efficient and miniaturized electronics, enabling the biosensor to move from bench testing to long term validation, up to its final application in human beings. In this spirit, we present a wireless programmable electronic platform for implantable chronic monitoring of fluorescent-based autonomous biosensors. This system is able to achieve extremely low power operation with bidirectional telemetry, based on the IEEE802.15.4-2003 protocol, thus enabling over three-year battery lifetime and wireless networking of multiple sensors. During the performance of single fluorescent-based sensor measurements, the circuit drives a laser diode, for sensor excitation, and acquires the amplified signals from four different photodetectors. In vitro functionality was preliminarily tested for both glucose and calcium monitoring, simply by changing the analyte-binding protein of the biosensor. Electronics performance was assessed in terms of timing, power consumption, tissue exposure to electromagnetic fields, and in vivo wireless connectivity. The final goal of the presented platform is to be integrated in a complete system for blood glucose level monitoring that may be implanted for at least one year under the skin of diabetic patients. Results reported in this paper may be applied to a wide variety of biosensors based on fluorescence intensity measurement.

Ambient light-based optical biosensing platform with smartphone-embedded illumination sensor.

Science.gov (United States)

Park, Yoo Min; Han, Yong Duk; Chun, Hyeong Jin; Yoon, Hyun C

2017-07-15

We present a hand-held optical biosensing system utilizing a smartphone-embedded illumination sensor that is integrated with immunoblotting assay method. The smartphone-embedded illumination sensor is regarded as an alternative optical receiver that can replaces the conventional optical analysis apparatus because the illumination sensor can respond to the ambient light in a wide range of wavelengths, including visible and infrared. To demonstrate the biosensing applicability of our system employing the enzyme-mediated immunoblotting and accompanying light interference, various types of ambient light conditions including outdoor sunlight and indoor fluorescent were tested. For the immunoblotting assay, the biosensing channel generating insoluble precipitates as an end product of the enzymatic reaction is fabricated and mounted on the illumination sensor of the smartphone. The intensity of penetrating light arrives on the illumination sensor is inversely proportional to the amount of precipitates produced in the channel, and these changes are immediately analyzed and quantified via smartphone software. In this study, urinary C-terminal telopeptide fragment of type II collagen (uCTX-II), a biomarker of osteoarthritis diagnosis, was tested as a model analyte. The developed smartphone-based sensing system efficiently measured uCTX-II in the 0-5ng/mL concentration range with a high sensitivity and accuracy under various light conditions. These assay results show that the illumination sensor-based optical biosensor is suitable for point-of-care testing (POCT). Copyright © 2016 Elsevier B.V. All rights reserved.

Three-dimensional simultaneous optical coherence tomography and confocal fluorescence microscopy for investigation of lung tissue.

Science.gov (United States)

Gaertner, Maria; Cimalla, Peter; Meissner, Sven; Kuebler, Wolfgang M; Koch, Edmund

2012-07-01

Although several strategies exist for a minimal-invasive treatment of patients with lung failure, the mortality rate of acute respiratory distress syndrome still reaches 30% at minimum. This striking number indicates the necessity of understanding lung dynamics on an alveolar level. To investigate the dynamical behavior on a microscale, we used three-dimensional geometrical and functional imaging to observe tissue parameters including alveolar size and length of embedded elastic fibers during ventilation. We established a combined optical coherence tomography (OCT) and confocal fluorescence microscopy system that is able to monitor the distension of alveolar tissue and elastin fibers simultaneously within three dimensions. The OCT system can laterally resolve a 4.9 μm line pair feature and has an approximately 11 μm full-width-half-maximum axial resolution in air. confocal fluorescence microscopy visualizes molecular properties of the tissue with a resolution of 0.75 μm (laterally), and 5.9 μm (axially) via fluorescence detection of the dye sulforhodamine B specifically binding to elastin. For system evaluation, we used a mouse model in situ to perform lung distension by application of different constant pressure values within the physiological regime. Our method enables the investigation of alveolar dynamics by helping to reveal basic processes emerging during artificial ventilation and breathing.

Extracting Optical Fiber Background from Surface-Enhanced Raman Spectroscopy Spectra Based on Bi-Objective Optimization Modeling.

Science.gov (United States)

Huang, Jie; Shi, Tielin; Tang, Zirong; Zhu, Wei; Liao, Guanglan; Li, Xiaoping; Gong, Bo; Zhou, Tengyuan

2017-08-01

We propose a bi-objective optimization model for extracting optical fiber background from the measured surface-enhanced Raman spectroscopy (SERS) spectrum of the target sample in the application of fiber optic SERS. The model is built using curve fitting to resolve the SERS spectrum into several individual bands, and simultaneously matching some resolved bands with the measured background spectrum. The Pearson correlation coefficient is selected as the similarity index and its maximum value is pursued during the spectral matching process. An algorithm is proposed, programmed, and demonstrated successfully in extracting optical fiber background or fluorescence background from the measured SERS spectra of rhodamine 6G (R6G) and crystal violet (CV). The proposed model not only can be applied to remove optical fiber background or fluorescence background for SERS spectra, but also can be transferred to conventional Raman spectra recorded using fiber optic instrumentation.

Angular shaping of fluorescence from synthetic opal-based photonic crystal.

Science.gov (United States)

Boiko, Vitalii; Dovbeshko, Galyna; Dolgov, Leonid; Kiisk, Valter; Sildos, Ilmo; Loot, Ardi; Gorelik, Vladimir

2015-01-01

Spectral, angular, and temporal distributions of fluorescence as well as specular reflection were investigated for silica-based artificial opals. Periodic arrangement of nanosized silica globules in the opal causes a specific dip in the defect-related fluorescence spectra and a peak in the reflectance spectrum. The spectral position of the dip coincides with the photonic stop band. The latter is dependent on the size of silica globules and the angle of observation. The spectral shape and intensity of defect-related fluorescence can be controlled by variation of detection angle. Fluorescence intensity increases up to two times at the edges of the spectral dip. Partial photobleaching of fluorescence was observed. Photonic origin of the observed effects is discussed.

A single-chip computer analysis system for liquid fluorescence

International Nuclear Information System (INIS)

Zhang Yongming; Wu Ruisheng; Li Bin

1998-01-01

The single-chip computer analysis system for liquid fluorescence is an intelligent analytic instrument, which is based on the principle that the liquid containing hydrocarbons can give out several characteristic fluorescences when irradiated by strong light. Besides a single-chip computer, the system makes use of the keyboard and the calculation and printing functions of a CASIO printing calculator. It combines optics, mechanism and electronics into one, and is small, light and practical, so it can be used for surface water sample analysis in oil field and impurity analysis of other materials

An optical method for reducing green fluorescence from urine during fluorescence-guided cystoscopy

DEFF Research Database (Denmark)

Lindvold, Lars René; Hermann, Gregers G

2016-01-01

Photodynamic diagnosis (PDD) of bladder tumour tissue significantly improves endoscopic diagnosis and treatment of bladder cancer in rigid cystoscopes in the operating theatre and thus reduces tumour recurrence. PDD comprises the use of blue light, which unfortunately excites green fluorescence...... this light source also is useful for exciting autofluorescence in healthy bladder mucosa. This autofluorescence then provides a contrast to the sensitized fluorescence (PDD) of tumours in the bladder....

Synthesis of dye/fluorescent functionalized dendrons based on cyclotriphosphazene

Directory of Open Access Journals (Sweden)

Aurélien Hameau

2011-11-01

Full Text Available Functionalized phenols based on tyramine were synthesized in order to be selectively grafted on to hexachlorocyclotriphosphazene, affording a variety of functionalized dendrons of type AB5. The B functions comprised fluorescent groups (dansyl or dyes (dabsyl, whereas the A function was provided by either an aldehyde or an amine. The characterization of these dendrons is reported. An unexpected behaviour of a fluorescent and water-soluble dendron based on dansyl groups in mixtures of dioxane/water was observed.

Fluorescence ELISA for sensitive detection of ochratoxin A based on glucose oxidase-mediated fluorescence quenching of CdTe QDs

International Nuclear Information System (INIS)

Liang, Yi; Huang, Xiaolin; Yu, Ruijin; Zhou, Yaofeng; Xiong, Yonghua

2016-01-01

The present study described a novel fluorescence enzyme-linked immunosorbent assay (ELISA) used to detect ochratoxin A (OTA) by using the glucose oxidase (GOx)-mediated fluorescence quenching of mercaptopropionic acid-capped CdTe quantum dots (MPA-QDs), in which GOx was used as an alternative to horseradish peroxidase (HRP) for the oxidization of glucose into hydrogen peroxide (H_2O_2) and gluconic acid. The MPA-QDs were used as a fluorescent signal output, whose fluorescence variation was extremely sensitive to the presence of H_2O_2 or hydrogen ions in the solution. Under the optimized conditions, the proposed fluorescence ELISA demonstrated a good linear detection of OTA in corn extract from 2.4 pg mL"−"1 to 625 pg mL"−"1 with a limit of detection of 2.2 pg mL"−"1, which was approximately 15-fold lower than that of conventional HRP-based ELISA. Our developed fluorescence immunoassay was also similar to HRP-based ELISA in terms of selectivity, accuracy, and reproducibility. In summary, this study was the first to use the GOx-mediated fluorescence quenching of QDs in immunoassay to detect OTA, offering a new possibility for the analysis of other mycotoxins and biomolecules. - Highlights: • A novel fluorescence ELISA was first developed for the detection of OTA by using GOx-mediated fluorescence quenching of QDs. • The pH- and H_2O_2-sensitive MPA-capped CdTe QDs were used as a fluorescent signal output to improve the detection sensitivity. • This novel method open up a different vision to detect other mycotoxins and biomolecules.

Optical and Microcantilever-Based Sensors for Real-Time In Situ Characterization of High-Level Waste

International Nuclear Information System (INIS)

Braun, Gilbert M.; Bryan, Samuel

2002-01-01

Fundamental research is being conducted to develop sensors for strontium that can be used in real-time to characterize high-level waste (HLW) process streams. Two fundamentally different approaches are being pursued, which have in common the dependence on highly selective molecular recognition agents. In one approach, an array of chemically selective sensors with sensitive fluorescent probes to signal the presence of the constituent of interest are coupled to fiber optics for remote analytical applications. The second approach employs sensitive microcantilever sensors that have been demonstrated to have unprecedented sensitivity in solution for Cs+ and CrO4 -. Selectivity in microcantilever-based sensors is achieved by modifying the surface of a gold-coated cantilever with a monolayer coating of an alkanethiol derivative of the molecular recognition agent. The approaches are complementary since fiber optic sensors can be deployed in the highly alkaline environment of HLW, bu t a method of immobilizing a fluorescent molecular recognition agents in a polymer film or bead on the surface of the optical fiber has yet to be demonstrated. The microcantilever-based sensors function by converting molecular complexation into surface stress, and they have been demonstrated to have the requisite sensitivity. However, we will investigate method of protecting Si or SiN microcantilever sensors in the highly alkaline environment of HLW while maintaining high selectivity. One objective of this project is to develop Sr(II) molecular recognition agents with rapidly established equilibria needed for real-time analysis, and initial research will focus on calixarene-crown ethers as a platform. Sensors for alkali metal ions, hydroxide, and temperature will be part of the array of sensor elements that will be demonstrated in this program for both the cantilever and fiber optic sensor approaches

Spectrally-resolved response properties of the three most advanced FRET based fluorescent protein voltage probes.

Directory of Open Access Journals (Sweden)

Hiroki Mutoh

Full Text Available Genetically-encoded optical probes for membrane potential hold the promise of monitoring electrical signaling of electrically active cells such as specific neuronal populations in intact brain tissue. The most advanced class of these probes was generated by molecular fusion of the voltage sensing domain (VSD of Ci-VSP with a fluorescent protein (FP pair. We quantitatively compared the three most advanced versions of these probes (two previously reported and one new variant, each involving a spectrally distinct tandem of FPs. Despite these different FP tandems and dissimilarities within the amino acid sequence linking the VSD to the FPs, the amplitude and kinetics of voltage dependent fluorescence changes were surprisingly similar. However, each of these fluorescent probes has specific merits when considering different potential applications.

Fluorescence-based classification of Caribbean coral reef organisms and substrates

Science.gov (United States)

Zawada, David G.; Mazel, Charles H.

2014-01-01

A diverse group of coral reef organisms, representing several phyla, possess fluorescent pigments. We investigated the potential of using the characteristic fluorescence emission spectra of these pigments to enable unsupervised, optical classification of coral reef habitats. We compiled a library of characteristic fluorescence spectra through in situ and laboratory measurements from a variety of specimens throughout the Caribbean. Because fluorescent pigments are not species-specific, the spectral library is organized in terms of 15 functional groups. We investigated the spectral separability of the functional groups in terms of the number of wavebands required to distinguish between them, using the similarity measures Spectral Angle Mapper (SAM), Spectral Information Divergence (SID), SID-SAM mixed measure, and Mahalanobis distance. This set of measures represents geometric, stochastic, joint geometric-stochastic, and statistical approaches to classifying spectra. Our hyperspectral fluorescence data were used to generate sets of 4-, 6-, and 8-waveband spectra, including random variations in relative signal amplitude, spectral peak shifts, and water-column attenuation. Each set consisted of 2 different band definitions: ‘optimally-picked’ and ‘evenly-spaced.’ The optimally-picked wavebands were chosen to coincide with as many peaks as possible in the functional group spectra. Reference libraries were formed from half of the spectra in each set and used for training purposes. Average classification accuracies ranged from 76.3% for SAM with 4 evenly-spaced wavebands to 93.8% for Mahalanobis distance with 8 evenly-spaced wavebands. The Mahalanobis distance consistently outperformed the other measures. In a second test, empirically-measured spectra were classified using the same reference libraries and the Mahalanobis distance for just the 8 evenly-spaced waveband case. Average classification accuracies were 84% and 87%, corresponding to the extremes in modeled

Gold and silver nanoparticles based superquenching of fluorescence: A review

Energy Technology Data Exchange (ETDEWEB)

Ghosh, Debanjana; Chattopadhyay, Nitin, E-mail: nitin.chattopadhyay@yahoo.com

2015-04-15

The short review highlights the recent advances on the gold and silver nanoparticles induced efficient quenching of fluorescence from various fluorophores looking at their promising use as optical rulers and chemo-/bio- sensors. The fluorescence quenching often leads to the increase in the Stern–Volmer constant (K{sub SV}~10{sup 7}–10{sup 10} mol{sup −1} dm{sup 3}) several orders of magnitude higher than the values observed for the normal photochemical quenching processes (~10{sup 2} mol{sup −1} dm{sup 3}). This amplified quenching has been termed as “super-quenching” or “hyper-quenching”. Energy transfer (ET) is established from the donor to the metal nanoparticles rationalizing these fast quenching processes. Considering the distance dependence of the ET process, Förster resonance energy transfer (FRET) and nanometal surface energy transfer (NSET) are ascribed to take place. These sensitive distance dependent phenomena serve as the spectroscopic ruler to measure the intra- or intermolecular distances between the interacting partners. In this account focus has been laid on the size dependent energy transfer and super- and hyper- quenching of the fluorescence of the donor moieties by the nanometals and their probable applications in sensing. Rationalization has been made for the nanoparticle induced huge enhancement in the quenching efficiency. The impact of this review lies in the possible application of these amplified quenching processes in designing high sensitive chemical and biological sensors. - Highlights: • Super efficient quenching of fluorescence of probes by gold and silver nanoparticles is highlighted. • The amplified fluorescence quenching of dyes and polymers is rationalized. • Energy transfer is assigned to be responsible for the efficient quenching process. • Amplified quenching has its potential use in designing sensitive chemical/biological sensors.

Gold and silver nanoparticles based superquenching of fluorescence: A review

International Nuclear Information System (INIS)

Ghosh, Debanjana; Chattopadhyay, Nitin

2015-01-01

The short review highlights the recent advances on the gold and silver nanoparticles induced efficient quenching of fluorescence from various fluorophores looking at their promising use as optical rulers and chemo-/bio- sensors. The fluorescence quenching often leads to the increase in the Stern–Volmer constant (K SV ~10 7 –10 10 mol −1 dm 3 ) several orders of magnitude higher than the values observed for the normal photochemical quenching processes (~10 2 mol −1 dm 3 ). This amplified quenching has been termed as “super-quenching” or “hyper-quenching”. Energy transfer (ET) is established from the donor to the metal nanoparticles rationalizing these fast quenching processes. Considering the distance dependence of the ET process, Förster resonance energy transfer (FRET) and nanometal surface energy transfer (NSET) are ascribed to take place. These sensitive distance dependent phenomena serve as the spectroscopic ruler to measure the intra- or intermolecular distances between the interacting partners. In this account focus has been laid on the size dependent energy transfer and super- and hyper- quenching of the fluorescence of the donor moieties by the nanometals and their probable applications in sensing. Rationalization has been made for the nanoparticle induced huge enhancement in the quenching efficiency. The impact of this review lies in the possible application of these amplified quenching processes in designing high sensitive chemical and biological sensors. - Highlights: • Super efficient quenching of fluorescence of probes by gold and silver nanoparticles is highlighted. • The amplified fluorescence quenching of dyes and polymers is rationalized. • Energy transfer is assigned to be responsible for the efficient quenching process. • Amplified quenching has its potential use in designing sensitive chemical/biological sensors

Graphene oxide based fluorescence resonance energy transfer and loop-mediated isothermal amplification for white spot syndrome virus detection.

Science.gov (United States)

Waiwijit, U; Phokaratkul, D; Kampeera, J; Lomas, T; Wisitsoraat, A; Kiatpathomchai, W; Tuantranont, A

2015-10-20

Graphene oxide (GO) is attractived for biological or medical applications due to its unique electrical, physical, optical and biological properties. In particular, GO can adsorb DNA via π-π stacking or non-covalent interactions, leading to fluorescence quenching phenomenon applicable for bio-molecular detection. In this work, a new method for white spot syndrome virus (WSSV)-DNA detection is developed based on loop-mediated isothermal amplification (LAMP) combined with fluorescence resonance energy transfer (FRET) between GO and fluorescein isothiocyanate-labeled probe (FITC-probe). The fluorescence quenching efficiency of FITC-probe was found to increase with increasing GO concentration and reached 98.7% at a GO concentration of 50 μg/ml. The fluorescence intensity of FITC-probe was recovered after hybridization with WSSV LAMP product with an optimal hybridization time of 10 min and increased accordingly with increasing amount of LAMP products. The detection limit was estimated to be as low as 10 copies of WSSV plasmid DNA or 0.6 fg of the total DNA extracted from shrimp infected with WSSV. In addition, no cross reaction was observed with other common shrimp viral pathogens. Therefore, the GO-FRET-LAMP technique is promising for fast, sensitive and specific detection of DNAs. Copyright © 2015 Elsevier B.V. All rights reserved.

Optically controllable molecular logic circuits

International Nuclear Information System (INIS)

Nishimura, Takahiro; Fujii, Ryo; Ogura, Yusuke; Tanida, Jun

2015-01-01

Molecular logic circuits represent a promising technology for observation and manipulation of biological systems at the molecular level. However, the implementation of molecular logic circuits for temporal and programmable operation remains challenging. In this paper, we demonstrate an optically controllable logic circuit that uses fluorescence resonance energy transfer (FRET) for signaling. The FRET-based signaling process is modulated by both molecular and optical inputs. Based on the distance dependence of FRET, the FRET pathways required to execute molecular logic operations are formed on a DNA nanostructure as a circuit based on its molecular inputs. In addition, the FRET pathways on the DNA nanostructure are controlled optically, using photoswitching fluorescent molecules to instruct the execution of the desired operation and the related timings. The behavior of the circuit can thus be controlled using external optical signals. As an example, a molecular logic circuit capable of executing two different logic operations was studied. The circuit contains functional DNAs and a DNA scaffold to construct two FRET routes for executing Input 1 AND Input 2 and Input 1 AND NOT Input 3 operations on molecular inputs. The circuit produced the correct outputs with all possible combinations of the inputs by following the light signals. Moreover, the operation execution timings were controlled based on light irradiation and the circuit responded to time-dependent inputs. The experimental results demonstrate that the circuit changes the output for the required operations following the input of temporal light signals

Tunable thin-film optical filters for hyperspectral microscopy

Science.gov (United States)

Favreau, Peter F.; Rich, Thomas C.; Prabhat, Prashant; Leavesley, Silas J.

2013-02-01

Hyperspectral imaging was originally developed for use in remote sensing applications. More recently, it has been applied to biological imaging systems, such as fluorescence microscopes. The ability to distinguish molecules based on spectral differences has been especially advantageous for identifying fluorophores in highly autofluorescent tissues. A key component of hyperspectral imaging systems is wavelength filtering. Each filtering technology used for hyperspectral imaging has corresponding advantages and disadvantages. Recently, a new optical filtering technology has been developed that uses multi-layered thin-film optical filters that can be rotated, with respect to incident light, to control the center wavelength of the pass-band. Compared to the majority of tunable filter technologies, these filters have superior optical performance including greater than 90% transmission, steep spectral edges and high out-of-band blocking. Hence, tunable thin-film optical filters present optical characteristics that may make them well-suited for many biological spectral imaging applications. An array of tunable thin-film filters was implemented on an inverted fluorescence microscope (TE 2000, Nikon Instruments) to cover the full visible wavelength range. Images of a previously published model, GFP-expressing endothelial cells in the lung, were acquired using a charge-coupled device camera (Rolera EM-C2, Q-Imaging). This model sample presents fluorescently-labeled cells in a highly autofluorescent environment. Linear unmixing of hyperspectral images indicates that thin-film tunable filters provide equivalent spectral discrimination to our previous acousto-optic tunable filter-based approach, with increased signal-to-noise characteristics. Hence, tunable multi-layered thin film optical filters may provide greatly improved spectral filtering characteristics and therefore enable wider acceptance of hyperspectral widefield microscopy.

Liposomal encapsulation of a near-infrared fluorophore enhances fluorescence quenching and reliable whole body optical imaging upon activation in vivo.

Science.gov (United States)

Tansi, Felista L; Rüger, Ronny; Rabenhold, Markus; Steiniger, Frank; Fahr, Alfred; Kaiser, Werner A; Hilger, Ingrid

2013-11-11

In the past decade, there has been significant progress in the development of water soluble near-infrared fluorochromes for use in a wide range of imaging applications. Fluorochromes with high photo and thermal stability, sensitivity, adequate pharmacological properties and absorption/emission maxima within the near infrared window (650-900 nm) are highly desired for in vivo imaging, since biological tissues show very low absorption and auto-fluorescence at this spectrum window. Taking these properties into consideration, a myriad of promising near infrared fluorescent probes has been developed recently. However, a hallmark of most of these probes is a rapid clearance in vivo, which hampers their application. It is hypothesized that encapsulation of the near infrared fluorescent dye DY-676-COOH, which undergoes fluorescence quenching at high concentrations, in the aqueous interior of liposomes will result in protection and fluorescence quenching, which upon degradation by phagocytes in vivo will lead to fluorescence activation and enable imaging of inflammation. Liposomes prepared with high concentrations of DY-676-COOH reveal strong fluorescence quenching. It is demonstrated that the non-targeted PEGylated fluorescence-activatable liposomes are taken up predominantly by phagocytosis and degraded in lysosomes. Furthermore, in zymosan-induced edema models in mice, the liposomes are taken up by monocytes and macrophages which migrate to the sites of inflammation. Opposed to free DY-676-COOH, prolonged stability and retention of liposomal-DY-676-COOH is reflected in a significant increase in fluorescence intensity of edema. Thus, protected delivery and fluorescence quenching make the DY-676-COOH-loaded liposomes a highly promising contrast agent for in vivo optical imaging of inflammatory diseases. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mechanical Damage Detection of Indonesia Local Citrus Based on Fluorescence Imaging

Science.gov (United States)

Siregar, T. H.; Ahmad, U.; Sutrisno; Maddu, A.

2018-05-01

Citrus experienced physical damage in peel will produce essential oils that contain polymethoxylated flavone. Polymethoxylated flavone is fluorescence substance; thus can be detected by fluorescence imaging. This study aims to study the fluorescence spectra characteristic and to determine the damage region in citrus peel based on fluorescence image. Pulung citrus from Batu district, East Java, as a famous citrus production area in Indonesia, was used in the experiment. It was observed that the image processing could detect the mechanical damage region. Fluorescence imaging can be used to classify the citrus into two categories, sound and defect citruses.

Fluorescence ELISA for sensitive detection of ochratoxin A based on glucose oxidase-mediated fluorescence quenching of CdTe QDs

Energy Technology Data Exchange (ETDEWEB)

Liang, Yi [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Jiangxi-OAI Joint Research Institute, Nanchang University, Nanchang 330047 (China); Huang, Xiaolin [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Yu, Ruijin [College of Science, Northwest A& F University, Yangling, Shaanxi 712100 (China); Zhou, Yaofeng [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Xiong, Yonghua, E-mail: yhxiongchen@163.com [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047 (China); Jiangxi-OAI Joint Research Institute, Nanchang University, Nanchang 330047 (China)

2016-09-14

The present study described a novel fluorescence enzyme-linked immunosorbent assay (ELISA) used to detect ochratoxin A (OTA) by using the glucose oxidase (GOx)-mediated fluorescence quenching of mercaptopropionic acid-capped CdTe quantum dots (MPA-QDs), in which GOx was used as an alternative to horseradish peroxidase (HRP) for the oxidization of glucose into hydrogen peroxide (H{sub 2}O{sub 2}) and gluconic acid. The MPA-QDs were used as a fluorescent signal output, whose fluorescence variation was extremely sensitive to the presence of H{sub 2}O{sub 2} or hydrogen ions in the solution. Under the optimized conditions, the proposed fluorescence ELISA demonstrated a good linear detection of OTA in corn extract from 2.4 pg mL{sup −1} to 625 pg mL{sup −1} with a limit of detection of 2.2 pg mL{sup −1}, which was approximately 15-fold lower than that of conventional HRP-based ELISA. Our developed fluorescence immunoassay was also similar to HRP-based ELISA in terms of selectivity, accuracy, and reproducibility. In summary, this study was the first to use the GOx-mediated fluorescence quenching of QDs in immunoassay to detect OTA, offering a new possibility for the analysis of other mycotoxins and biomolecules. - Highlights: • A novel fluorescence ELISA was first developed for the detection of OTA by using GOx-mediated fluorescence quenching of QDs. • The pH- and H{sub 2}O{sub 2}-sensitive MPA-capped CdTe QDs were used as a fluorescent signal output to improve the detection sensitivity. • This novel method open up a different vision to detect other mycotoxins and biomolecules.

Fluorescence microscopy.

Science.gov (United States)

Sanderson, Michael J; Smith, Ian; Parker, Ian; Bootman, Martin D

2014-10-01

Fluorescence microscopy is a major tool with which to monitor cell physiology. Although the concepts of fluorescence and its optical separation using filters remain similar, microscope design varies with the aim of increasing image contrast and spatial resolution. The basics of wide-field microscopy are outlined to emphasize the selection, advantages, and correct use of laser scanning confocal microscopy, two-photon microscopy, scanning disk confocal microscopy, total internal reflection, and super-resolution microscopy. In addition, the principles of how these microscopes form images are reviewed to appreciate their capabilities, limitations, and constraints for operation. © 2014 Cold Spring Harbor Laboratory Press.

A fibre optic chemical sensor for the detection of cocaine

Science.gov (United States)

Nguyen, T. Hien; Sun, Tong; Grattan, Kenneth T. V.; Hardwick, S. A.

2010-09-01

A fibre-optic chemical sensor for the detection of cocaine has been developed, based on a molecularly imprinted polymer (MIP) containing a fluorescein moiety as the signalling group. The fluorescent MIP was formed and covalently attached to the distal end of an optical fibre. The sensor exhibited an increase in fluorescence intensity in response to cocaine in the concentration range of 0 - 500 μM in aqueous acetonitrile mixtures with good reproducibility over 24 h. Selectivity for cocaine over others drugs has also been demonstrated.

Bead-based competitive fluorescence immunoassay for sensitive and rapid diagnosis of cyanotoxin risk in drinking water.

Science.gov (United States)

Yu, Hye-Weon; Jang, Am; Kim, Lan Hee; Kim, Sung-Jo; Kim, In S

2011-09-15

Due to the increased occurrence of cyanobacterial blooms and their toxins in drinking water sources, effective management based on a sensitive and rapid analytical method is in high demand for security of safe water sources and environmental human health. Here, a competitive fluorescence immunoassay of microcystin-LR (MCYST-LR) is developed in an attempt to improve the sensitivity, analysis time, and ease-of-manipulation of analysis. To serve this aim, a bead-based suspension assay was introduced based on two major sensing elements: an antibody-conjugated quantum dot (QD) detection probe and an antigen-immobilized magnetic bead (MB) competitor. The assay was composed of three steps: the competitive immunological reaction of QD detection probes against analytes and MB competitors, magnetic separation and washing, and the optical signal generation of QDs. The fluorescence intensity was found to be inversely proportional to the MCYST-LR concentration. Under optimized conditions, the proposed assay performed well for the identification and quantitative analysis of MCYST-LR (within 30 min in the range of 0.42-25 μg/L, with a limit of detection of 0.03 μg/L). It is thus expected that this enhanced assay can contribute both to the sensitive and rapid diagnosis of cyanotoxin risk in drinking water and effective management procedures.

Carbon quantum dots-based recyclable real-time fluorescence assay for alkaline phosphatase with adenosine triphosphate as substrate.

Science.gov (United States)

Qian, Zhaosheng; Chai, Lujing; Tang, Cong; Huang, Yuanyuan; Chen, Jianrong; Feng, Hui

2015-03-03

A convenient, reliable, and highly sensitive real-time assay for alkaline phosphatase (ALP) activity in the continuous and recyclable way is established on the basis of aggregation and disaggregation of carbon quantum dots (CQDs) through the competitive assay approach. CQDs and adenosine triphosphate (ATP) were used as the fluorescent indicator and substrate for ALP activity assessment, respectively. Richness of carboxyl groups on the surface of CQDs enables their severe aggregation triggered by cerium ions, which results in effective fluorescence quenching. Under the catalytic hydrolysis of ALP, ATP can be rapidly transformed to phosphate ions. Stronger affinity of phosphate ions to cerium ions than carboxyl groups is taken advantage of to achieve fluorescence recovery induced by redispersion of CQDs in the presence of ALP and ATP. Quantitative evaluation of ALP activity in a broad range from 4.6 to 383.3 U/L with the detection limit of 1.4 U/L can be realized in this way, which endows the assay with high enough sensitivity for practical detection in human serum. The assay can be used in a recyclable way for more than three times since the generated product CePO4 as a precipitate can be easily removed from the standard assay system. This strategy broadens the sensing application of fluorescent CQDs with excellent biocompatibility and provides an example based on disaggregation in optical probe development.

An eco-friendly molecularly imprinted fluorescence composite material based on carbon dots for fluorescent detection of 4-nitrophenol

International Nuclear Information System (INIS)

Hao, Tongfan; Wei, Xiao; Nie, Yijing; Zhou, Zhiping; Xu, Yeqing; Yan, Yongsheng

2016-01-01

We on report an eco-friendly molecularly imprinted material based on carbon dots (C-dots) via a facile and efficient sol–gel polymerization for selective fluorescence detection of 4-nitrophenol (4-NP). The amino-modified C-dots were firstly synthesized by a hydrothermal process using citric acid as the carbon source and poly(ethyleneimine) as the surface modifier, and then after a sol–gel molecular imprinting process, the molecularly imprinted fluorescence material was obtained. The material (MIP-C-dots) showed strong fluorescence from C-dots and high selectivity due to the presence of a molecular imprint. After the detection conditions were optimized, the relative fluorescence intensity (F_0/F) of MIP-C-dots presented a good linearity with 4-NP concentrations in the linear range of 0.2 − 50 μmol L"-"1 with a detection limit (3σ/k) of 0.06 μmol L"-"1. In addition, the correlation coefficient was 0.9978 and the imprinting factor was 2.76. The method was applicable to the determination of trace 4-NP in Yangtze River water samples and good recoveries from 92.6–107.3 % were obtained. The present study provides a general strategy to fabricate materials based on C-dots with good fluorescence property for selective fluorescence detection of organic pollutants. (author)

Fluorescence quenching of Rhodamine B base by two amines

Science.gov (United States)

Bakkialakshmi, S.; Selvarani, P.; Chenthamarai, S.

2013-03-01

Fluorescence quenching of Rhodamine B base (RhB) in DMF solution has been studied at different concentrations of the amine Triethyl amine (TEA) and n-butyl amine (NBA) at room temperature. It has been observed that the fluorescence intensity of RhB decrease with increase in the concentration of the TEA and NBA. It has been observed that the quenching due to amines proceeds via dynamic quenching process. The rate constants for the quenching process have been calculated using Stern-Volmer equation. Time resolved fluorescence study and 1H NMR spectral study have also been carried out and discussed.

Realization of an optical interferometer based on holographic optics ...

Indian Academy of Sciences (India)

The paper describes a simple and cost effective method for the realization of an optical interferometer based on holographic optics, which use minimal bulk optical components. The optical arrangement in the proposed method involves a very simple alignment procedure and inexpensive holographic recording material is ...

In Vivo Deep Tissue Fluorescence and Magnetic Imaging Employing Hybrid Nanostructures.

Science.gov (United States)

Ortgies, Dirk H; de la Cueva, Leonor; Del Rosal, Blanca; Sanz-Rodríguez, Francisco; Fernández, Nuria; Iglesias-de la Cruz, M Carmen; Salas, Gorka; Cabrera, David; Teran, Francisco J; Jaque, Daniel; Martín Rodríguez, Emma

2016-01-20

Breakthroughs in nanotechnology have made it possible to integrate different nanoparticles in one single hybrid nanostructure (HNS), constituting multifunctional nanosized sensors, carriers, and probes with great potential in the life sciences. In addition, such nanostructures could also offer therapeutic capabilities to achieve a wider variety of multifunctionalities. In this work, the encapsulation of both magnetic and infrared emitting nanoparticles into a polymeric matrix leads to a magnetic-fluorescent HNS with multimodal magnetic-fluorescent imaging abilities. The magnetic-fluorescent HNS are capable of simultaneous magnetic resonance imaging and deep tissue infrared fluorescence imaging, overcoming the tissue penetration limits of classical visible-light based optical imaging as reported here in living mice. Additionally, their applicability for magnetic heating in potential hyperthermia treatments is assessed.

State-of-the-Art Fluorescence Fluctuation-Based Spectroscopic Techniques for the Study of Protein Aggregation.

Science.gov (United States)

Kitamura, Akira; Kinjo, Masataka

2018-03-23

Neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease, Parkinson's disease, and Huntington's disease, are devastating proteinopathies with misfolded protein aggregates accumulating in neuronal cells. Inclusion bodies of protein aggregates are frequently observed in the neuronal cells of patients. Investigation of the underlying causes of neurodegeneration requires the establishment and selection of appropriate methodologies for detailed investigation of the state and conformation of protein aggregates. In the current review, we present an overview of the principles and application of several methodologies used for the elucidation of protein aggregation, specifically ones based on determination of fluctuations of fluorescence. The discussed methods include fluorescence correlation spectroscopy (FCS), imaging FCS, image correlation spectroscopy (ICS), photobleaching ICS (pbICS), number and brightness (N&B) analysis, super-resolution optical fluctuation imaging (SOFI), and transient state (TRAST) monitoring spectroscopy. Some of these methodologies are classical protein aggregation analyses, while others are not yet widely used. Collectively, the methods presented here should help the future development of research not only into protein aggregation but also neurodegenerative diseases.

Optical-optical double resonance, laser induced fluorescence, and revision of the signs of the spin-spin constants of the boron carbide (BC) free radical

Science.gov (United States)

Sunahori, Fumie X.; Nagarajan, Ramya; Clouthier, Dennis J.

2015-12-01

The cold boron carbide free radical (BC X 4Σ-) has been produced in a pulsed discharge free jet expansion using a precursor mixture of trimethylborane in high pressure argon. High resolution laser induced fluorescence spectra have been obtained for the B 4Σ--X 4Σ- and E 4Π-X 4Σ- band systems of both 11BC and 10BC. An optical-optical double resonance (OODR) scheme was implemented to study the finer details of both band systems. This involved pumping a single rotational level of the B state with one laser and then recording the various allowed transitions from the intermediate B state to the final E state with a second laser by monitoring the subsequent E-X ultraviolet fluorescence. In this fashion, we were able to prove unambiguously that, contrary to previous studies, the spin-spin constant λ is negative in the ground state and positive in the B 4Σ- excited state. It has been shown that λ″ expected based on a semiempirical second order perturbation theory calculation of the magnitude of the spin-spin constant. The OODR spectra have also been used to validate our assignments of the complex and badly overlapped E 4Π-X 4Σ- 0-0 and 1-0 bands of 11BC. The E-X 0-0 band of 10BC was found to be severely perturbed. The ground state main electron configuration is …3σ24σ25σ11π22π0 and the derived bond lengths show that there is a 0.03 Å contraction in the B state, due to the promotion of an electron from the 4σ antibonding orbital to the 5σ bonding orbital. In contrast, the bond length elongates by 0.15 Å in the E state, a result of promoting an electron from the 5σ bonding orbital to the 2π antibonding orbitals.

Fluorescence confocal microscopy for pathologists.

Science.gov (United States)

Ragazzi, Moira; Piana, Simonetta; Longo, Caterina; Castagnetti, Fabio; Foroni, Monica; Ferrari, Guglielmo; Gardini, Giorgio; Pellacani, Giovanni

2014-03-01

Confocal microscopy is a non-invasive method of optical imaging that may provide microscopic images of untreated tissue that correspond almost perfectly to hematoxylin- and eosin-stained slides. Nowadays, following two confocal imaging systems are available: (1) reflectance confocal microscopy, based on the natural differences in refractive indices of subcellular structures within the tissues; (2) fluorescence confocal microscopy, based on the use of fluorochromes, such as acridine orange, to increase the contrast epithelium-stroma. In clinical practice to date, confocal microscopy has been used with the goal of obviating the need for excision biopsies, thereby reducing the need for pathological examination. The aim of our study was to test fluorescence confocal microscopy on different types of surgical specimens, specifically breast, lymph node, thyroid, and colon. The confocal images were correlated to the corresponding histological sections in order to provide a morphologic parallel and to highlight current limitations and possible applications of this technology for surgical pathology practice. As a result, neoplastic tissues were easily distinguishable from normal structures and reactive processes such as fibrosis; the use of fluorescence enhanced contrast and image quality in confocal microscopy without compromising final histologic evaluation. Finally, the fluorescence confocal microscopy images of the adipose tissue were as accurate as those of conventional histology and were devoid of the frozen-section-related artefacts that can compromise intraoperative evaluation. Despite some limitations mainly related to black/white images, which require training in imaging interpretation, this study confirms that fluorescence confocal microscopy may represent an alternative to frozen sections in the assessment of margin status in selected settings or when the conservation of the specimen is crucial. This is the first study to employ fluorescent confocal microscopy on

Example-Based Super-Resolution Fluorescence Microscopy.

Science.gov (United States)

Jia, Shu; Han, Boran; Kutz, J Nathan

2018-04-23

Capturing biological dynamics with high spatiotemporal resolution demands the advancement in imaging technologies. Super-resolution fluorescence microscopy offers spatial resolution surpassing the diffraction limit to resolve near-molecular-level details. While various strategies have been reported to improve the temporal resolution of super-resolution imaging, all super-resolution techniques are still fundamentally limited by the trade-off associated with the longer image acquisition time that is needed to achieve higher spatial information. Here, we demonstrated an example-based, computational method that aims to obtain super-resolution images using conventional imaging without increasing the imaging time. With a low-resolution image input, the method provides an estimate of its super-resolution image based on an example database that contains super- and low-resolution image pairs of biological structures of interest. The computational imaging of cellular microtubules agrees approximately with the experimental super-resolution STORM results. This new approach may offer potential improvements in temporal resolution for experimental super-resolution fluorescence microscopy and provide a new path for large-data aided biomedical imaging.

An extremely sensitive monoboronic acid based fluorescent sensor for glucose

International Nuclear Information System (INIS)

Sun Xiangying; Liu Bin; Jiang Yunbao

2004-01-01