Ujjal Kumar Sur

SERS study of bacteria using biosynthesized silver nanoparticles as the SERS substrate

Surface-enhanced Raman scattering (SERS) spectroscopy has great advantages as a spectroscopic analytical tool due to the large enhancement of the weak Raman signal and thereby facilitates suitable identification of chemical and biological systems. SERS can be utilized as a powerful tool to identify pathogens like bacteria. However, it is difficult to fabricate a homogeneous SERS active substrate in biosensing applications to obtain a uniform, stable and highly reproducible SERS signal. In this paper, we have used biosynthesized silver nanoparticles as the SERS active substrate to identify bacteria with different cell wall compositions. The silver nanoparticles were synthesized using the leaf extract of Neolamarckia cadamba as the source of reducing and stabilizing agents. The pathogen detection by using the SERS technique using biosynthesized silver nanoparticles represents a novel approach for rapid microbial diagnostics, where SERS can be directly applied to clinical samples rather than pure cultured bacteria.

Synthesis and characterization of stable aqueous dispersions of graphene

A stable aqueous dispersion (5 mg ml−1) of graphene was synthesized by a simple protocol based on three-step reduction of graphene oxide (GO) dispersion synthesized using the modified version of Hummers and Offeman method. Reduction of GO was carried out using sodium borohydride, hydrazine hydrate and dimethyl hydrazine as reducing agents. The chemically synthesized graphene was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible absorption spectroscopy, Fourier transform infrared (FTIR) and Raman spectroscopy, thermogravimetric analysis (TGA), optical microscopy. The stability of aqueous dispersions of graphene was confirmed through zeta potential measurements and the negative zeta potentials of 55–60 mV were obtained indicating the high stability of aqueous graphene dispersions.

Room temperature green synthesis of anisotropic gold nanoparticles using novel biological fruit extract

ABSTRACT Herein, we reported the room temperature green synthesis of anisotropic gold nanoparticles from the aqueous Cordia myxa fruit extract, which can concurrently serve as the source for both the reducing and stabilizing agents. In the X-ray diffraction pattern, the identified Bragg reflections corresponded to the (111), (200), and (220) sets of lattice planes, which can be indexed based on the face center cubic structures of gold. They are in different morphologies such as multiple twinned pentagonal shaped octahedron and hexagonal shaped icosahedron with their size ranging from 20 to 50 nm as evident from the transmission electron microscopy images.

Synthesis of Mesoporous Nanocrystalline Zirconia by Surfactant-Assisted Hydrothermal Approach

In this paper, we have reported the chemical synthesis of thermally stable mesoporous nanocrystalline zirconia with high surface area using a surfactant-assisted hydrothermal approach. We have employed different type of surfactants such as CTAB, SDS and Triton X-100 in our synthesis. The synthesized nanocrystalline zirconia multistructures exhibit various morphologies such as rod, mortar-pestle with different particle sizes. We have characterized the zirconia multistructures by X-ray diffraction study, Field emission scanning electron microscopy, Attenuated total refection infrared spectroscopy, UV-Vis spectroscopy and photoluminescence spectroscopy. The thermal stability of as synthesized zirconia multistructures was studied by thermo gravimetric analysis, which shows the high thermal stability of nanocrystalline zirconia around 900 °C temperature.

Optical, dielectric, electronic and morphological study of biologically synthesized zinc sulphide nanoparticles using Moringa oleifera leaf extract and quantitative analysis of chemical components present in the leaf extract

The biosynthesis of zinc sulphide nanoparticles with ∼30 nm diameter using the leaf extract of Moringa oleifera is reported here. The biosynthesized nanoparticles exhibit high stability for a period of three months as supported by the observed negative zeta potential values of 45–55 mV. Two peaks were observed at 427 and 560 nm in the photoluminescence spectrum of ZnS nanoparticles. The dielectrics as well as electronic properties of ZnS nanoparticles were systematically investigated. Thin-layer-chromatography densitometric technique was employed for the simultaneous quantification of the major chemical components present in the extract of M. oleifera leaves. The average amount of observed biomolecules such as crypto-chlorogenic acid, isoquercetin and astragalin were found to be 0.0423, 0.0467 and 0.0634% dry weight, respectively.