Arup Ratan Mandal

Synthesis of five metal based nanocomposite via ultrasonic high temperature spray pyrolysis with excellent antioxidant and antibacterial activity

A unique five metal (Zn, Cu, Ni, Fe, and Mg) based nanocomposite material was prepared via ultrasonication high temperature spray pyrolysis maintained at 1200 °C. The influence of different concentrations (0.001 M, 0.01 M, and 1 M) on size and crystalline phase were analyzed. The nanocomposite exhibited excellent antioxidant and antibacterial activity.

Nitrobacter sp. extract mediated biosynthesis of Ag2O NPs with excellent antioxidant and antibacterial potential for biomedical application

In this study, extracellular extract of plant growth promoting bacterium, Nitrobacter sp. is used for the bioconversion of AgNO3 (silver nitrate) into Ag2O (silver oxide nanoparticles). It is an easy, ecofriendly and single step method for Ag2O NPs synthesis. The bio-synthesized nanoparticles were characterized using different techniques. UV-Vis results showed the maximum absorbance around 450 nm. XRD result shows the particles to have faced centered cubic (fcc) crystalline nature. FTIR analysis reveals the functional groups that are involved in bioconversion such as C-N, N-H and C=O. Energy-dispersive X-ray spectroscopy (EDAX) spectrum confirms that the prepared nanoparticle is Ag2O NPs. Particle size distribution result reveals that the average particle size is around 40 nm. The synthesized Ag2O NPs found to be almost spherical in shape. Biosynthesized Ag2O NPs possess good antibacterial activity against selected Gram positive and Gram negative bacterial strains namely Salmonella typhimurium, Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae when compared to standard antibiotic. In addition, Ag2O NPs exhibits excellent free radical scavenging activity with respect to dosage. Thus, this study is a new approach to use soil bacterial extract for the production of Ag2O NPs for biomedical application.

Direct experimental observation of salt induced aspect ratio tunable PFPT silver-nanowire formation: SERS-based ppt level Hg2+ sensing from ground water

A plausible explanation based on real-time direct experimental observation has been put forward to explain the formation of common salt (NaF, NaCl, NaBr, and NaI) induced aspect ratio tunable Pentagonal Faceted Pyramidal Tipped (PFPT) silver-nanowires by considering the solubility product of the in situ generated silver halides, binding affinity of the added halides at the {111} facets on the growing front, and the free energy associated with the crystallographic planes (obtained from HRTEM study) as the driving forces. Aspect ratio dependent Raman activity was verified by using 4-mercaptobenzoic acid (4-MBA) as a Raman tag and due to the preferential binding of Hg2+ on the pyramidal tip of the silver-nanowire [i.e., {111} facet], as all the {100} facets are blocked by insoluble silver halides, controlled leaching of the nanowires offers the best-possible Raman platform for the ultra sensitive detection of Hg2+ contamination (up to 50 ppt) from ground water.

Polymer Stabilized Undoped and Copper Doped Cadmium Sulphide Nanoparticles: Polymer Crosslinked, Optical, and Thermal Stability

Cadmium sulfide (CdS) nanoparticles synthesized by utilization of wet chemical technique are grown in polyvinyl alcohol (PVA) matrix. X-ray diffraction (XRD) pattern shows the typical inter-planar spacing corresponding to the cubic phase of CdS. High-resolution transmission electron microscopy (HRTEM) studies show the nanoparticles formation with diameter around 11 nm. Particle size is further determined by dynamic light scattering (DLS) measurement. The polymerization of PVA is confirmed by fourier transform infrared (FTIR) spectroscopy of CdS nanoparticles. UV-visible optical spectroscopy study shows that sharp excitonic bands are largely blue shifted from the absorption onset of bulk CdS and inter band transition of copper doped samples. Thermal stability of the samples is measured by thermogravimetric (TG) analysis which is also studied in details.