Author
G. V. Pavan Kumar
Other affiliations: Purdue University, Indian Institute of Science, Jawaharlal Nehru Centre for Advanced Scientific Research
Bio: G. V. Pavan Kumar is an academic researcher from Indian Institute of Science Education and Research, Pune. The author has contributed to research in topics: Plasmon & Raman scattering. The author has an hindex of 20, co-authored 105 publications receiving 3232 citations. Previous affiliations of G. V. Pavan Kumar include Purdue University & Indian Institute of Science.
Papers published on a yearly basis
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TL;DR: By utilizing dual excitation of plasmons at metal-fluid interface, this work creates interacting assemblies of metal nanoparticles, which may be further harnessed in dynamic lithography of dispersed nanostructures and have implications in realizing optically addressable, plasmofluidic, single-molecule detection platforms.
Abstract: Single-molecule surface-enhanced Raman scattering (SM-SERS) is one of the vital applications of plasmonic nanoparticles. The SM-SERS sensitivity critically depends on plasmonic hot-spots created at the vicinity of such nanoparticles. In conventional fluid-phase SM-SERS experiments, plasmonic hot-spots are facilitated by chemical aggregation of nanoparticles. Such aggregation is usually irreversible, and hence, nanoparticles cannot be re-dispersed in the fluid for further use. Here, we show how to combine SM-SERS with plasmon polariton-assisted, reversible assembly of plasmonic nanoparticles at an unstructured metal–fluid interface. One of the unique features of our method is that we use a single evanescent-wave optical excitation for nanoparticle assembly, manipulation and SM-SERS measurements. Furthermore, by utilizing dual excitation of plasmons at metal–fluid interface, we create interacting assemblies of metal nanoparticles, which may be further harnessed in dynamic lithography of dispersed nanostructures. Our work will have implications in realizing optically addressable, plasmofluidic, single-molecule detection platforms. Plasmonic hot-spot generation in solution is not reversible for single-molecule surface-enhanced Raman scattering, which limits its applications. Patra et al.tackle this problem by integrating this technique with thermo-plasmon-assisted reconfiguration of nanoparticles at a metal–fluid interface.
1,705 citations
TL;DR: This work synthesis and characterization of a set of p300-HAT-specific small-molecule inhibitors from a natural nonspecific HAT inhibitor, garcinol, found to be nontoxic to T cells, inhibit histone acetylation of HIV infected cells, and consequently inhibit the multiplication of HIV.
195 citations
TL;DR: The core-shell NP with hot spots can be used for ultratrace analysis of important biomolecules such as histone acetyltranferase p300, a human transcriptional coactivator protein this article.
Abstract: The vicinity of metallic nanostructures that provides intense optical fields is termed as "hot spot". Any molecule in close proximity to these hot spots will give rise to an increased surface-enhanced Raman spectroscopic (SERS) signal. We have synthesized Ag core-Au shell (core-shell) nanoparticles (NP) with nanopores, which act as hot spots in the SERS measurements. We have demonstrated a large enhancement in SERS studies of various molecules using core-shell NP with hot spots, which is better than using silver nanoparticles. The core-shell NP with hot spots can be used for ultratrace analysis of important biomolecules such as histone acetyltranferase p300, a human transcriptional coactivator protein. The core-shell NP does not change the biomolecule's physical and chemical property upon adsorption, which makes it biocompatible. The core-shell NP carrying hot spots with high SERS enhancement would be ideally suited for in vivo studies of biological systems.
159 citations
TL;DR: Recently, a number of plasmonic nano-architectures have been harnessed for surface enhanced Raman scattering (SERS) as discussed by the authors, including nanosphere dimers, individual nanocubes, nanotriangular arrays, nano-pyramid shells, individual and assembly of nanorods, nanowires, and nanotips.
Abstract: Surface enhanced Raman scattering (SERS) is an optical spectroscopy technique with single molecule sensitivity and chemical specificity. The electromagnetic enhancement mechanism of SERS is facilitated by the localized surface plasmons of metallic nanostructures utilized in experiments. The magnitude of the local optical field created by the plasmonic nanostructure depends on parameters such as size, shape, morphology, arrangement, and local environment of the nanostructure. By tuning these parameters, electromagnetic hot spots can be created to facilitate ultra-sensitive, subwavelength SERS detection platforms. In recent years, there have been a number of innovations in nanofabrication and synthesis of plasmonic nanostructures. This has led to a variety of plasmonic nano-architectures that can be harnessed for SERS. Recently investigated plasmonic nanostructures in the context of SERS include nanosphere dimers, individual nanocubes, nanotriangular arrays, nano-pyramid shells, individual and assembly of nanorods, nanowires, and nanotips, and some unconventional nano-architectures. Challenges in fundamental and application aspects of SERS remain for future research.
114 citations
TL;DR: The synthesis of trifluoromethyl phenyl benzamides and their effect on histone acetyltransferase (HAT) activity of p300 is reported and Raman spectroscopic analysis of the complexes of histone-modifying enzymes and their modulators are described, for the first time, which may be highly useful for therapeutic applications.
Abstract: Reversible acetylation of nucleosomal histones and nonhistone proteins play pivotal roles in the regulation of all the DNA templated phenomenon. Dysfunction of the enzymes involved in the acetylation/deacetylation leads to several diseases. Therefore, these enzymes are the targets for new generation therapeutics. Here, we report the synthesis of trifluoromethyl phenyl benzamides and their effect on histone acetyltransferase (HAT) activity of p300. One of these benzamides, CTPB (N-(4-chloro-3-trifluoromethyl-phenyl)-2-ethoxy-6-pentadecyl-benzamide), was discovered as a potent activator of the p300 HAT activity. We have found that pentadecyl hydrocarbon chain of CTPB is required to activate the HAT only under certain context. Furthermore, our results show that the relative position of -CF 3 and -Cl in CTB (N-(4-chloro-3-trifluoromethyl-phenyl)-2-ethoxy-benzamide) is also very critical for the activation. Surface-enhanced Raman spectroscopy (SERS) of p300 and the HAT activator complexes evidently suggest that the activation of HAT activity is achieved by the alteration of p300 structure. Therefore, apart from elucidating the chemical basis for small molecule mediated activation of p300, this report also describes, for the first time, Raman spectroscopic analysis of the complexes of histone-modifying enzymes and their modulators, which may be highly useful for therapeutic applications.
90 citations
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28 Jul 2005
TL;DR: PfPMP1）与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。
18,940 citations
2,702 citations
TL;DR: Chemical applications of SERS cover a broad range of topics such as catalysis and spectroelectrochemistry, single-molecule detection, and (bio)analytical chemistry.
Abstract: Surface-enhanced Raman scattering (SERS) has become a mature vibrational spectroscopic technique during the last decades and the number of applications in the chemical, material, and in particular life sciences is rapidly increasing. This Review explains the basic theory of SERS in a brief tutorial and-based on original results from recent research-summarizes fundamental aspects necessary for understanding SERS and provides examples for the preparation of plasmonic nanostructures for SERS. Chemical applications of SERS are the centerpiece of this Review. They cover a broad range of topics such as catalysis and spectroelectrochemistry, single-molecule detection, and (bio)analytical chemistry.
1,817 citations
TL;DR: By utilizing dual excitation of plasmons at metal-fluid interface, this work creates interacting assemblies of metal nanoparticles, which may be further harnessed in dynamic lithography of dispersed nanostructures and have implications in realizing optically addressable, plasmofluidic, single-molecule detection platforms.
Abstract: Single-molecule surface-enhanced Raman scattering (SM-SERS) is one of the vital applications of plasmonic nanoparticles. The SM-SERS sensitivity critically depends on plasmonic hot-spots created at the vicinity of such nanoparticles. In conventional fluid-phase SM-SERS experiments, plasmonic hot-spots are facilitated by chemical aggregation of nanoparticles. Such aggregation is usually irreversible, and hence, nanoparticles cannot be re-dispersed in the fluid for further use. Here, we show how to combine SM-SERS with plasmon polariton-assisted, reversible assembly of plasmonic nanoparticles at an unstructured metal–fluid interface. One of the unique features of our method is that we use a single evanescent-wave optical excitation for nanoparticle assembly, manipulation and SM-SERS measurements. Furthermore, by utilizing dual excitation of plasmons at metal–fluid interface, we create interacting assemblies of metal nanoparticles, which may be further harnessed in dynamic lithography of dispersed nanostructures. Our work will have implications in realizing optically addressable, plasmofluidic, single-molecule detection platforms. Plasmonic hot-spot generation in solution is not reversible for single-molecule surface-enhanced Raman scattering, which limits its applications. Patra et al.tackle this problem by integrating this technique with thermo-plasmon-assisted reconfiguration of nanoparticles at a metal–fluid interface.
1,705 citations
TL;DR: Luminescence in the visible region, especially by clusters protected with proteins, with a large Stokes shift, has been used for various sensing applications, down to a few tens of molecules/ions, in air and water.
Abstract: Atomically precise pieces of matter of nanometer dimensions composed of noble metals are new categories of materials with many unusual properties. Over 100 molecules of this kind with formulas such as Au25(SR)18, Au38(SR)24, and Au102(SR)44 as well as Ag25(SR)18, Ag29(S2R)12, and Ag44(SR)30 (often with a few counterions to compensate charges) are known now. They can be made reproducibly with robust synthetic protocols, resulting in colored solutions, yielding powders or diffractable crystals. They are distinctly different from nanoparticles in their spectroscopic properties such as optical absorption and emission, showing well-defined features, just like molecules. They show isotopically resolved molecular ion peaks in mass spectra and provide diverse information when examined through multiple instrumental methods. Most important of these properties is luminescence, often in the visible–near-infrared window, useful in biological applications. Luminescence in the visible region, especially by clusters prot...
1,443 citations