The Experts below are selected from a list of 12666 Experts worldwide ranked by ideXlab platform
Sergei G Kazarian - One of the best experts on this subject based on the ideXlab platform.
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Attenuated Total Reflection fourier transform infrared atr ftir imaging of tissues and live cells
Chemical Society Reviews, 2016Co-Authors: K Andrew L Chan, Sergei G KazarianAbstract:FTIR spectroscopic imaging is a label-free, non-destructive and chemically specific technique that can be utilised to study a wide range of biomedical applications such as imaging of biopsy tissues, fixed cells and live cells, including cancer cells. In particular, the use of FTIR imaging in Attenuated Total Reflection (ATR) mode has attracted much attention because of the small, but well controlled, depth of penetration and corresponding path length of infrared light into the sample. This has enabled the study of samples containing large amounts of water, as well as achieving an increased spatial resolution provided by the high refractive index of the micro-ATR element. This review is focused on discussing the recent developments in FTIR spectroscopic imaging, particularly in ATR sampling mode, and its applications in the biomedical science field as well as discussing the future opportunities possible as the imaging technology continues to advance.
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Attenuated Total Reflection-Fourier transform infrared spectroscopic imaging of pharmaceuticals in microfluidic devices
Biomicrofluidics, 2016Co-Authors: Andrew V. Ewing, Graham S Clarke, Sergei G KazarianAbstract:© 2016 Author(s).The poor aqueous solubility of many active pharmaceutical ingredients presents challenges for effective drug delivery. In this study, the combination of Attenuated Total Reflection (ATR)-FTIR spectroscopic imaging with specifically designed polydimethylsiloxane microfluidic devices to study drug release from pharmaceutical formulations has been developed. First, the high-throughput analysis of the dissolution of micro-formulations studied under flowing conditions has been introduced using a model formulation of ibuprofen and polyethylene glycol. The behaviour and release of the drug was monitored in situ under different pH conditions. In contrast to the neutral solution, where both the drug and excipient dissolved at a similar rate, structural change from the molecularly dispersed to a crystalline form of ibuprofen was characterised in the obtained spectroscopic images and the corresponding ATR-FTIR spectra for the experiments carried out in the acidic medium. Further investigations into the behaviour of the drug after its release from formulations (i.e., dissolved drug) were also undertaken. Different solutions of sodium ibuprofen dissolved in a neutral medium were studied upon contact with acidic conditions. The phase transition from a dissolved species of sodium ibuprofen to the formation of solid crystalline ibuprofen was revealed in the microfluidic channels. This innovative approach could offer a promising platform for high-throughput analysis of a range of micro-formulations, which are of current interest due to the advent of 3D printed pharmaceutical and microparticulate delivery systems. Furthermore, the ability to study dissolved drug in solution under flowing conditions can be useful for the studies of the diffusion of drugs into tissues or live cells.
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micro Attenuated Total Reflection fourier transform infrared micro atr ft ir spectroscopic imaging with variable angles of incidence
Applied Spectroscopy, 2015Co-Authors: Alessandra Vichi, Tomasz P Wrobel, Malgorzata Baranska, Sergei G KazarianAbstract:The control of the angle of incidence in Attenuated Total Reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy allows for the probing of the sample at different depths of penetration of the evanescent wave. This approach has been recently coupled with macro-imaging capability using a diamond ATR accessory. In this paper, the design of optical apertures for the micro-germanium (Ge) ATR objective is presented for an FT-IR spectroscopic imaging microscope, allowing measurements with different angles of incidence. This approach provides the possibility of three-dimensional (3D) profiling in micro-ATR FT-IR imaging mode. The proof of principle results for measurements of polymer laminate samples at different angles of incidence confirm that controlling the depth of penetration is possible using a Ge ATR objective with added apertures.
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high throughput thermal stability analysis of a monoclonal antibody by Attenuated Total Reflection ft ir spectroscopic imaging
Analytical Chemistry, 2014Co-Authors: Maxime Bouletaudet, Bernadette Byrne, Sergei G KazarianAbstract:The use of biotherapeutics, such as monoclonal antibodies, has markedly increased in recent years. It is thus essential that biotherapeutic production pipelines are as efficient as possible. For the production process, one of the major concerns is the propensity of a biotherapeutic antibody to aggregate. In addition to reducing bioactive material recovery, protein aggregation can have major effects on drug potency and cause highly undesirable immunological effects. It is thus essential to identify processing conditions which maximize recovery while avoiding aggregation. Heat resistance is a proxy for long-term aggregation propensity. Thermal stability assays are routinely performed using various spectroscopic and scattering detection methods. Here, we evaluated the potential of macro Attenuated Total Reflection Fourier transform infrared (ATR-FT-IR) spectroscopic imaging as a novel method for the high-throughput thermal stability assay of a monoclonal antibody. This chemically specific visualization method has the distinct advantage of being able to discriminate between monomeric and aggregated protein. Attenuated Total Reflection is particularly suitable for selectively probing the bottom of vessels, where precipitated aggregates accumulate. With focal plane array detection, we tested 12 different buffer conditions simultaneously to assess the effect of pH and ionic strength on protein thermal stability. Applying the Finke model to our imaging kinetics allowed us to determine the rate constants of nucleation and autocatalytic growth. This analysis demonstrated the greater stability of our immunoglobulin at higher pH and moderate ionic strength, revealing the key role of electrostatic interactions. The high-throughput approach presented here has significant potential for analyzing the stability of biotherapeutics as well as any other biological molecules prone to aggregation.
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micro and macro Attenuated Total Reflection fourier transform infrared spectroscopic imaging
Applied Spectroscopy, 2010Co-Authors: Sergei G Kazarian, K Andrew L ChanAbstract:Fourier transform infrared (FT-IR) spectroscopic imaging has become a very powerful method in chemical analysis. In this review paper we describe a variety of opportunities for obtaining FT-IR images using the Attenuated Total Reflection (ATR) approach and provide an overview of fundamental aspects, accessories, and applications in both micro- and macro-ATR imaging modes. The advantages and versatility of both ATR imaging modes are discussed and the spatial resolution of micro-ATR imaging is demonstrated. Micro-ATR imaging has opened up many new areas of study that were previously precluded by inadequate spatial resolution (polymer blends, pharmaceutical tablets, cross-sections of blood vessels or hair, surface of skin, single live cells, cancerous tissues). Recent applications of ATR imaging in polymer research, biomedical and forensic sciences, objects of cultural heritage, and other complex materials are outlined. The latest advances include obtaining spatially resolved chemical images from different depths within a sample, and surface-enhanced images for macro-ATR imaging have also been presented. Macro-ATR imaging is a valuable approach for high-throughput analysis of materials under controlled environments. Opportunities exist for chemical imaging of dynamic aqueous systems, such as dissolution, diffusion, microfluidics, or imaging of dynamic processes in live cells.
Koichiro Tanaka - One of the best experts on this subject based on the ideXlab platform.
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characterizing hydration state in solution using terahertz time domain Attenuated Total Reflection spectroscopy
Chemical Physics Letters, 2008Co-Authors: Takashi Arikawa, Masaya Nagai, Koichiro TanakaAbstract:We propose a novel method to characterize hydration states from dielectric responses of solutions in terahertz (THz) frequency region. Hydration states can be evaluated quantitatively from a complex dielectric function derived from a theory with a local field correction. We demonstrated this method in disaccharide (sucrose and trehalose) water solutions using the THz time-domain Attenuated Total Reflection (TD-ATR) spectroscopy. The method successfully evaluates the hydration state and its concentration dependence, providing a new tool to investigate the picosecond dynamics of hydration directly.
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Terahertz time-domain Attenuated Total Reflection spectroscopy in water and biological solution
International Journal of Infrared and Millimeter Waves, 2006Co-Authors: Masaya Nagai, Hiroyuki Yada, Takashi Arikawa, Koichiro TanakaAbstract:We demonstrate time-domain Attenuated Total Reflection spectroscopy in terahertz frequency region. Geometry of the Reflection measurement is well optimized to obtain accurate optical constants of water or aqueous biomolecular system. We determine the dielectric constants of distilled water and sucrose solutions with this technique. This technique will open new aspects in the research field of biological systems in water.
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destructive interference effect on surface plasmon resonance in terahertz Attenuated Total Reflection
Optics Express, 2005Co-Authors: Hideki Hirori, Masaya Nagai, Koichiro TanakaAbstract:We investigate the surface plasmon resonance at the interface between air and n-type (100) oriented-InAs as an active material with a time-domain Attenuated Total Reflection technique with coherent terahertz pulses. The characteristic spectra of the Attenuated Total reflectivity and phase shift caused by surface plasmon are observed in the Otto configuration. The surface plasmon resonance frequency and the phase jump strongly depend on the wave vector of the evanescent wave, the refractive index of the prism, and the incident angle of the terahertz pulses and the distance between the prism and active material. These features can no longer be explained with conventional Otto's approximation. We show that the interference effect between the electromagnetic wave reflected at the prism-air interface and that reemitted from excited surface plasmon plays a key role in the surface plasmon resonance.
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Attenuated Total Reflection spectroscopy in time domain using terahertz coherent pulses
Japanese Journal of Applied Physics, 2004Co-Authors: Hideki Hirori, Masaya Nagai, Kumiko Yamashita, Koichiro TanakaAbstract:We present a novel technique for time-domain Attenuated Total Reflection spectroscopy in the terahertz (THz) frequency region. The advantage of this technique is that it can be used to access samples with various shapes and optical properties without changing the optical setup. The technique is applied to determine the complex dielectric constants in InAs and distilled liquid water.
Xinghua Xia - One of the best experts on this subject based on the ideXlab platform.
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antenna array enhanced Attenuated Total Reflection ir analysis in an aqueous solution
Nanoscale, 2019Co-Authors: Zhendong Yan, Zhenlin Wang, William Morrison, Xinghua XiaAbstract:Attenuated Total Reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) is a powerful technique that provides structural and functional information during dynamic reactions in aqueous solutions. One existing limitation is the sensitivity to extract the signals of trace-level analytes from the background water in situ and in real time. Here, we proposed a novel ATR-SEIRAS platform that integrated a large-scale triangle gold antenna array onto a conventional ATR-IR platform to increase the sensitivity of this analytical technique. A square centimeter level well-ordered gold antenna array was fabricated onto an Si prism via nanosphere lithography. The size-dependent antenna array resonance had weak correlation with the incident polarization and antenna orientation, allowing antenna array-enhanced IR detection without the requirement of a microscope. In addition, the antenna resonance shift that occurred due to analyte adsorption-induced refractive index variation could be minimized benefiting from the high refractive index of Si (3.4). As a demonstration, we dynamically monitored the adsorption of the trace levels of proteins on top of the antenna array with a real signal enhancement factor larger than 300. Our platform opens an avenue to apply antenna array-enhanced IR spectroscopy in an aqueous environment measured via commercial IR instruments, which is extremely promising for the interfacial applications that require signal enhancement.
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water as a universal infrared probe for bioanalysis in aqueous solution by Attenuated Total Reflection surface enhanced infrared absorption spectroscopy
Analytical Chemistry, 2018Co-Authors: Yang Liu, Wenjing Bao, Xinghua Xia, Qianwen Zhang, Hongyuan ChenAbstract:Monitoring the properties and reactions of biomolecules at their interface has attracted ever-growing interest. Here, we propose an approach of infrared analysis technique that utilizes water molecule as a universal probe for in situ and label free monitoring of interfacial bioevents in aqueous solution with high sensitivity. The strong infrared (IR) signal of O–H stretching vibrations from the repelled water is used to sensitively reveal the kinetics of interfacial bioevents at molecular level based on the steric displacement of water using an Attenuated Total Reflection–surface enhanced infrared absorption spectroscopy. Using interfacial immuno-recognition and DNA hybridization as demonstrations, water IR probe offers 26 and 34 times higher sensitivity and even 200 and 86 times lower detection limit for immunosensing and DNA sensing, respectively, as compared to the traditional IR molecular fingerprints.
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graphene plasmon enhanced ir biosensing for in situ detection of aqueous phase molecules with an Attenuated Total Reflection mode
Analytical Chemistry, 2018Co-Authors: Bo Zheng, Zhenlin Wang, Caifeng Shi, Xin Yang, Xinghua XiaAbstract:Graphene plasmon has attracted extensive interest due to the unprecedented electromagnetic confinement, long propagation distance, and tunable plasmonic frequency. Successful applications of graphene plasmon as infrared sensors have been recently demonstrated, yet they are mainly focused on solid/solid and solid/gas interfaces analysis. Herein, we, for the first time, propose a graphene plasmon-enhanced infrared sensor based on Attenuated Total Reflection configuration for in situ analysis of aqueous-phase molecules. This IR sensor includes a boron-doped graphene (BG) nanodisk array fabricated on top of a ZnSe prism surface that supports Attenuated Total Reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRA). Our ATR-SEIRA platform is efficient and straightforward for in situ and label-free monitoring of the interaction of biomolecules without interference from the environments, allowing for the extraction of instant spectroscopic information in a complex biological event. Utilizing the ...
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Attenuated Total Reflection surface enhanced infrared absorption spectroscopy a powerful technique for bioanalysis
Journal of Analysis and Testing, 2017Co-Authors: Bo Zheng, Kang Wang, Qianwen Zhang, Yang Liu, Caifeng Shi, Fengbin Wang, Xinghua XiaAbstract:Attenuated Total Reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) has recently been proven to be a powerful tool for bioanalysis. It enables in situ and in real-time observation of dynamic processes occurring on specific interface, revealing rich structural and functional information of biomolecules at sub monolayer level. The aim of this general review was to give an overview of the cutting edge applications of ATR-SEIRAS. We start with description of the basic configuration of the standard ATR-SEIRAS platform. The enhanced mechanisms and methods to fabricate enhanced substrates are then presented. We discuss the recent developments, challenges and applications of ATR-SEIRAS in bioanalysis, mainly focusing on DNA analysis, protein behavior and cell properties. Finally, further development of the ATR-SEIRAS technique with enhanced sensitivity, improved time and spatial resolutions will be prospected.
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distance determined sensitivity in Attenuated Total Reflection surface enhanced infrared absorption spectroscopy aptamer antigen compared to antibody antigen
Chemical Communications, 2014Co-Authors: Wenjing Bao, Z B Yan, Min Wang, Yun Zhao, Kang Wang, Xinghua Xia, Zhenlin WangAbstract:Distance-dependent signal intensity in immunoassay by Attenuated Total Reflection-surface enhanced infrared absorption spectroscopy is demonstrated by controlling the distance of target proteins away from the enhancement substrate. Based on this optical near-field effect, sensitive detection of protein molecules with a detection limit of 0.6 nM and investigation of the kinetics and thermodynamics of protein–aptamer/antibody interactions can be achieved.
Igor K Lednev - One of the best experts on this subject based on the ideXlab platform.
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forensic hair differentiation using Attenuated Total Reflection fourier transform infrared atr ft ir spectroscopy
Applied Spectroscopy, 2016Co-Authors: Jeremy M Manheim, Kyle C Doty, Gregory Mclaughlin, Igor K LednevAbstract:Hair and fibers are common forms of trace evidence found at crime scenes. The current methodology of microscopic examination of potential hair evidence is absent of statistical measures of performance, and examiner results for identification can be subjective. Here, Attenuated Total Reflection (ATR) Fourier transform-infrared (FT-IR) spectroscopy was used to analyze synthetic fibers and natural hairs of human, cat, and dog origin. Chemometric analysis was used to differentiate hair spectra from the three different species, and to predict unknown hairs to their proper species class, with a high degree of certainty. A species-specific partial least squares discriminant analysis (PLSDA) model was constructed to discriminate human hair from cat and dog hairs. This model was successful in distinguishing between the three classes and, more importantly, all human samples were correctly predicted as human. An external validation resulted in zero false positive and false negative assignments for the human class. From a forensic perspective, this technique would be complementary to microscopic hair examination, and in no way replace it. As such, this methodology is able to provide a statistical measure of confidence to the identification of a sample of human, cat, and dog hair, which was called for in the 2009 National Academy of Sciences report. More importantly, this approach is non-destructive, rapid, can provide reliable results, and requires no sample preparation, making it of ample importance to the field of forensic science.
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identification of species blood by Attenuated Total Reflection atr fourier transform infrared ft ir spectroscopy
Analytical and Bioanalytical Chemistry, 2015Co-Authors: Ewelina Mistek, Igor K LednevAbstract:Blood is one of the most common and informative forms of biological evidence found at a crime scene. A very crucial step in forensic investigations is identifying a blood stain's origin. The standard methods currently employed for analyzing blood are destructive to the sample and time-consuming. In this study, Attenuated Total Reflection (ATR) Fourier transform infrared (FT-IR) spectroscopy is used as a confirmatory, nondestructive, and rapid method for distinction between human and animal (nonhuman) blood. Partial least squares-discriminant analysis (PLS-DA) models were built and demonstrated complete separation between human and animal donors, as well as distinction between three separate species: human, cat, and dog. Classification predictions of unknown blood donors were performed by the model, resulting in 100 % accuracy. This study demonstrates ATR FT-IR spectroscopy's great potential for blood stain analysis and species discrimination, both in the lab and at a crime scene since portable ATR FT-IR instrumentation is commercially available.
K Andrew L Chan - One of the best experts on this subject based on the ideXlab platform.
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Attenuated Total Reflection fourier transform infrared atr ftir imaging of tissues and live cells
Chemical Society Reviews, 2016Co-Authors: K Andrew L Chan, Sergei G KazarianAbstract:FTIR spectroscopic imaging is a label-free, non-destructive and chemically specific technique that can be utilised to study a wide range of biomedical applications such as imaging of biopsy tissues, fixed cells and live cells, including cancer cells. In particular, the use of FTIR imaging in Attenuated Total Reflection (ATR) mode has attracted much attention because of the small, but well controlled, depth of penetration and corresponding path length of infrared light into the sample. This has enabled the study of samples containing large amounts of water, as well as achieving an increased spatial resolution provided by the high refractive index of the micro-ATR element. This review is focused on discussing the recent developments in FTIR spectroscopic imaging, particularly in ATR sampling mode, and its applications in the biomedical science field as well as discussing the future opportunities possible as the imaging technology continues to advance.
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micro and macro Attenuated Total Reflection fourier transform infrared spectroscopic imaging
Applied Spectroscopy, 2010Co-Authors: Sergei G Kazarian, K Andrew L ChanAbstract:Fourier transform infrared (FT-IR) spectroscopic imaging has become a very powerful method in chemical analysis. In this review paper we describe a variety of opportunities for obtaining FT-IR images using the Attenuated Total Reflection (ATR) approach and provide an overview of fundamental aspects, accessories, and applications in both micro- and macro-ATR imaging modes. The advantages and versatility of both ATR imaging modes are discussed and the spatial resolution of micro-ATR imaging is demonstrated. Micro-ATR imaging has opened up many new areas of study that were previously precluded by inadequate spatial resolution (polymer blends, pharmaceutical tablets, cross-sections of blood vessels or hair, surface of skin, single live cells, cancerous tissues). Recent applications of ATR imaging in polymer research, biomedical and forensic sciences, objects of cultural heritage, and other complex materials are outlined. The latest advances include obtaining spatially resolved chemical images from different depths within a sample, and surface-enhanced images for macro-ATR imaging have also been presented. Macro-ATR imaging is a valuable approach for high-throughput analysis of materials under controlled environments. Opportunities exist for chemical imaging of dynamic aqueous systems, such as dissolution, diffusion, microfluidics, or imaging of dynamic processes in live cells.
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Attenuated Total Reflection ft ir spectroscopic imaging of protein crystallization
Analytical Chemistry, 2009Co-Authors: K Andrew L Chan, Lata Govada, Roslyn M Bill, Naomi E Chayen, Sergei G KazarianAbstract:Protein crystallization is of strategic and commercial relevance in the post-genomic era because of its pivotal role in structural proteomics projects. Although protein structures are crucial for understanding the function of proteins and to the success of rational drug design and other biotechnology applications, obtaining high quality crystals is a major bottleneck to progress. The major means of obtaining crystals is by massive-scale screening of a target protein solution with numerous crystallizing agents. However, when crystals appear in these screens, one cannot easily know if they are crystals of protein, salt, or any other molecule that happens to be present in the trials. We present here a method based on Attenuated Total Reflection (ATR)-FT-IR imaging that reliably identifies protein crystals through a combination of chemical specificity and the visualizing capability of this approach, thus solving a major hurdle in protein crystallization. ATR-FT-IR imaging was successfully applied to study the crystallization of thaumatin and lysozyme in a high-throughput manner, simultaneously from six different solutions. This approach is fast as it studies protein crystallization in situ and provides an opportunity to examine many different samples under a range of conditions.
