Indian Association for the Cultivation of Science

About: Indian Association for the Cultivation of Science is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Excited state & Catalysis. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

Fabrication of luminescent CdS nanoparticles on short-peptide-based hydrogel nanofibers: tuning of optoelectronic properties.

Abstract: The pH-induced self-assembly of three synthetic tripeptides in water medium is used to immobilize luminescent CdS nanoparticles. These peptides form a nanofibrillar network structure upon gelation in aqueous medium at basic pH values (pH 11.0-13.0), and the fabrication of CdS nanoparticles on the gel nanofiber confers the luminescent property to these gels. Atomic force microscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy clearly reveal the presence of CdS nanoparticles in a well-defined array on the gel nanofibers. This is a convenient way to make organic nanofiber-inorganic nanoparticle hybrid nanocomposite systems. The size of the CdS nanoparticles remains almost same before and after deposition on the gel nanofiber. Photoluminescence (PL) measurement of the CdS nanoparticles upon deposition on the gel nanofibers shows a significant blue shift in the emission spectrum of the nanoparticles, and there is a considerable change in the PL gap energy of the CdS nanoparticles after immobilization on different gel nanofibrils. This finding suggests that the optoelectronic properties of CdS nanoparticles can be tuned upon deposition on gel nanofibers without changing the size of the nanoparticles.

Advances in Coating Chemistry in Deriving Soluble Functional Nanoparticle

Abstract: Nanoparticle-based probes are emerging as alternatives to molecular probes with several advantages. A variety of water-soluble functional nanoparticles and nanobioconjugates need to be prepared and tested for this research. Development of appropriate coating chemistries is the key in deriving such functional nanoparticles. Herein we summarize different coating approaches those we have developed and compared them in the context of currently available coating methods, for the synthesis of soluble functional nanoparticles. We have focused on conventional ligand exchange, interdigited bilayer strategy, silica coating, polyacrylate coating, and imidazole based polymer coating and found that cross-linked coating, specifically by polyacrylate, provides a superior colloidal stability of nanoparticles. The robust coating provides the opportunity to explore various conjugation chemistries involving nanoparticle and to derive different soluble nanobioconjugates. A library of functional nanoprobes with hydrodynamic d...

Controlled synthesis of spin glass nickel oxide nanoparticles and evaluation of their potential antimicrobial activity: A cost effective and eco friendly approach

Abstract: Development of an easy sustainable synthetic pathway towards oxide nanomaterials (NMs) is a necessary challenge for nanotechnology research workers. Additionally, antimicrobial activity of oxide nanoparticles against multi drug resistance pathogenic bacteria motivates scientists to focus their research on oxide materials. We report here a cost effective, simple and eco-friendly pathway of synthesizing NiO nanoparticles (NPs). X-ray diffraction and energy dispersive X-ray study confirmed their crystallinity and composition. Field emission scanning electron microscope (FESEM) was employed to understand their surface architecture and the dimension of synthesized NiO NPs were found to be 20–30 nm from transmission electron microscope (TEM) study. The as synthesized NiO demonstrated typical spin glass behaviour which is one advantage of our synthetic procedure. Antimicrobial properties of NiO NPs were investigated using Gram negative and Gram positive bacteria and their bactericidal effects were determined from minimum inhibitory concentrations (MIC) and Minimum bactericidal concentrations (MBC). Haemolytic activity revealed the nontoxic nature of the NPs towards the blood proteins at MBC. TEM images of bacteria cells treated with NiO NPs showed irreversible damages to the cell wall leading to cell death. In light of our findings a possible mechanism of the antimicrobial effect of NiO NPs has been proposed.

Fabrication and Luminescent Properties of c-Axis Oriented ZnO−ZnS Core−Shell and ZnS Nanorod Arrays by Sulfidation of Aligned ZnO Nanorod Arrays

Abstract: In this paper, we report the preparation of vertically aligned ZnO−ZnS core−shell and ZnS nanorod arrays with crystallographic orientation along the c-axis by sulfidation of aligned ZnO nanorod arrays. The ZnO nanorod arrays were prepared by a surfactant assisted soft chemical method on a sol−gel derived ZnO thin film. Partial conversion of the ZnO nanorod surface to ZnS at 400 °C in an H2S and argon gas mixture produces ZnO−ZnS core−shell structures, whereas the complete conversion at 600 °C produces well-aligned ZnS nanorods. The influence of the sulfidation time and annealing temperature on the conversion of ZnO nanorods to ZnO−ZnS core−shell nanorods is investigated. TEM studies revealed that the sulfidation process begins at the surface of the ZnO nanorods, which gradually increase inward, retaining the morphology and following the crystal orientation of the ZnO core. The nanostructures showed enhanced UV emission properties. The described procedures open a way to convert a microstructured material i...