Hirdyesh Mishra

Bio: Hirdyesh Mishra is an academic researcher from Banaras Hindu University. The author has contributed to research in topics: Molecular orbital & Density functional theory. The author has an hindex of 20, co-authored 65 publications receiving 1086 citations. Previous affiliations of Hirdyesh Mishra include University of Maryland, Baltimore County & Kumaun University.

Surface plasmon coupled metal enhanced spectral and charge transport properties of poly(3,3'''-dialkylquarterthiophene) Langmuir Schaefer films.

Abstract: The coupling of organic molecule excitons with metal nano-structure surface plasmons can improve the performance of optoelectronic devices. This paper presents the effect of localized silver metal surface plasmons on spectral as well as charge transport properties of ordered molecular Langmuir Schaefer (LS) films of a fluorescent conducting multifunctional organic polymer: poly (3,3′′′-dialkylquarterthiophene) [PQT-12]. The stability and thickness of the PQT-12 LS film were studied by the pressure vs. area isotherm curve. Atomic force microscopy images indicate the formation of a smooth ordered polymer thin LS film of PQT-12 over silver nanostructure island films [SNIF] (∼40 to 50 nm in size). Raman, electronic absorption and fluorescence spectral measurements of the PQT-12 LS film, near SNIF i.e. the near field, show a plasmon coupled enhancement of ∼13 fold in the intensity of Raman bands along with a two-fold enhancement in the absorption band (531 nm) and a six-fold enhancement in the fluorescence band (665 nm) coupled with a decrease in fluorescence decay time with improved photostability as compared to an identical control sample containing no SNIF i.e. the far field condition. These results indicate the formation of a plasmon coupled unified fluorophore system due to adsorption of the PQT-12 LS film over SNIF. The effect of plasmonic coupling is also studied by applying an electric field in sandwiched structures of Al/PQT-12 LS/SNIF/ITO with respect to Al/PQT-12 LS/ITO. Nearly three orders of magnitude enhancement in the current density (J–V plot) of the PQT-12 LS film is observed in the presence of SNIF, which further increases, on illuminating the film by green laser light [532 nm], while the fluorescence intensity and decay time decrease. X-ray photoelectron spectroscopic measurements of SNIF also show a red shift in 3d3/2 and 3d5/2 transitions of silver in the PQT-12 coated LS film, which indicates partial charge transfer from the PQT-12 polymer backbone to SNIF and causes an enhancement in conductivity. This again supports the formation of a field controlled radiating plasmon coupled fluorophore unified system. These findings show greater potential in developing a voltage controlled high photon flux electroluminescent material for multifarious applications.

UV to NIR Surface Plasmon Coupled and Metal-Enhanced Fluorescence Using Indium Thin Films: Application to Intrinsic (Label-less) Protein Fluorescence Detection

Abstract: Surface plasmon coupled fluorescence (SPCF) and metal enhanced fluorescence (MEF) over a broad wavelength range from UV to NIR are demonstrated from 20 nm thin indium films. Steady-state and time-resolved fluorescence measurements of fluorophores deposited on the indium thin films indicate enhancement of the fluorescence intensity along with decreases in decay times, both in MEF and SPCF modes, accompanied by an increase in photostability. MEF was found to be more pronounced for the red emission dye with respect to a blue emission dye. A completely p-polarized directional emission for three fluorophores from a hemicylindrical prism at 44° indicates surface plasmons couple with the near field dipoles at the interface of the indium-sample. The evanescent waves generated at the interface are calculated to penetrate more deeply for longer wavelength excitation with respect to shorter wavelengths, and the penetration depth nearly doubles in comparison to that of the widely used silver thin films. As an applica...

New triorganotin(IV) complexes of quinolone antibacterial drug sparfloxacin: Synthesis, structural characterization, DFT studies and biological activity

Abstract: A new series of triorganotin(IV) complexes of sparfloxacin (HL) having general formula R3SnL (where L is the monoanion of sparfloxacin (HL) and R = Me (1)/n-Bu (2)/Ph (3)/Cy (4)) have been synthesized and characterized by elemental analysis, IR, NMR (1H, 13C, 119Sn), 2D-HETCOR, ESI-MS and UV-Vis studies. These investigations suggest that, in these 1:1 monomeric derivatives the sparfloxacin ligand acts as monoanionic bidentate coordinating through the Ocarboxylate and Opyridone, and the polyhedron around tin is intermediate between pseudotetrahedral and cis-trigonal bipyramidal, with Opyridone and two organic groups in equatorial plane and the carboxylate oxygen and the third organic group in axial positions. The proposed structures have been validated by density functional theory (DFT) based quantum chemical calculations at B3LYP/6-31G(d,p)/Def2-SVP(Sn) level of theory. A detailed electronic structure calculations were performed at this level of theory to calculate atomic charges at the selected atoms, molecular electrostatic potential (MEP) map to assign sites on the surface of the molecules, the selected conceptual-DFT based global reactivity descriptors to obtain an insight into the structure and reactivity behaviour, and the frontier molecular orbital analysis to analyze the nature of frontier orbitals. All the complexes were screened for their in vitro antibacterial activity against two Gram-positive and five Gram-negative bacterial strains. All the complexes exhibited promising antibacterial activity as compared to sparfloxacin against all the chosen strains.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

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。

Principles Of Fluorescence Spectroscopy

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The unique role of nanoparticles in nanomedicine: imaging, drug delivery and therapy

Abstract: This critical review will present the role of nanoparticles (NPs) in the directions that are vital to the new field of nanomedicine, including imaging and drug delivery. We reflect on the physical properties that make NPs advantageous for in vivo efficacy, and review recent advances in major NP based biomedical applications. Critical questions of transport, uptake, and clearance will be discussed and illustrated through the success and opportunities of NP imaging and therapy on a photodynamic therapy (PDT) based NP system that has been developed in our lab over the past decade (540 references).

Hybrid materials based on lanthanide organic complexes: a review

Abstract: A great deal of research has been carried out on lanthanide organic complex-based organic-inorganic hybrid materials in the last decade. This critical review begins with a formulation of the fundamentals of lanthanide organic complex luminescence, and presents various current designed ideas, synthetic routes, luminescence behaviors and potentials of the latest advanced (a) sol-gel materials, (b) mesoporous materials, (c) titania materials, (d) ionic liquids and ionogels, (e) polymers, and (f) bifunctional magnetic-optical composites based on lanthanide organic complexes. Finally, challenges and opportunities for further improvement of organic-inorganic hybrid luminescent materials based on lanthanide organic complexes will be discussed.