Raghunandan Deshpande

Biosynthesis and stabilization of Au and Au–Ag alloy nanoparticles by fungus, Fusarium semitectum

Abstract Crystallized and spherical-shaped Au and Au–Ag alloy nanoparticles have been synthesized and stabilized using a fungus, F . semitectum in an aqueous system. Aqueous solutions of chloroaurate ions for Au and chloroaurate and Ag+ ions (1 : 1 ratio) for Au–Ag alloy were treated with an extracellular filtrate of F . semitectum biomass for the formation of Au nanoparticles (AuNP) and Au–Ag alloy nanoparticles (Au–AgNP). Analysis of the feasibility of the biosynthesized nanoparticles and core–shell alloy nanoparticles from fungal strains is particularly significant. The resultant colloidal suspensions are highly stable for many weeks. The obtained Au and Au–Ag alloy nanoparticles were characterized by the surface plasmon resonance (SPR) peaks using a UV-vis spectrophotometer, and the structure, morphology and size were determined by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and transmission electron microscopy (TEM). Possible optoelectronics and medical applications of these nanoparticles are envisaged.

Preparation and Characterization of Polypyrrole Silver Nanocomposites via Interfacial Polymerization

Conducting polypyrrole silver (Ppy-AgNC) nanocomposite was synthesized by an interfacial polymerization method. Ag+ ions from the AgNO3 solution were taken in the formation of Ppy-AgNC. The incorporated silver was confirmed by X-ray diffraction (XRD). During the polymerization in a nitrate ion-containing solution, the impregnation leads to the formation of metallic silver. The size distribution of Ag into the polymer is confirmed by transmission electron microscopy (TEM), and proves the formation of a uniform species with spherical particles of Ag (mean diameter of 8-12 nm) branching at the border of Ppy. The thermal behavior of the material was studied by thermogravimetric measurements.

Emphasized Mechanistic Antimicrobial Study of Biofunctionalized Silver Nanoparticles on Model Proteus mirabilis

Antimicrobial study of biofunctionalized silver nanoparticles has been done with the emphasis on its mechanism on both gram positive and negative bacteria. The biofunctionalized silver nanoparticles are employed considering their importance in green chemistry with respect to easy synthesis, usefulness, and economic synthetic procedure involved. The stability of these nanoparticles was determined by zeta potential analyzer. The probable mechanism of antibacterial activity was performed on Proteus mirabilis by field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDAX) study which does not show the presence of silver. The free radicals generated by silver nanoparticles were responsible for lethal antibacterial activity by rupturing the cell surface which causes improper nutrient and signal supply. Free radical scavenging efficacy of silver nanoparticles was confirmed by 1,1-Diphenyl-2-picrylhydrazyl (DPPH) method. AgNP enhanced the membrane leakage of reducing sugars by destroying the proteins existing on the cell wall. These nanoparticles are found to be toxic against human pathogens and are highly effective on Staphylococcus aureus. The effect of silver nanoparticles is concentration dependent and independent of the type of strains used.

Bio-functionalized gold nanoparticles: Benign effect in Sprague-Dawley rats by intravenous administration

Gold nanoparticles offer a great promise in clinical research. Despite various applications of the metal nanoparticles it is challenging to implement in vivo in clinical applications. This aspect is deprived of understanding the biological mechanisms that occurs in the cells. In this report we have evaluated application of AuNP on the safety profile at different doses (100, 200, and 500 μg/kg Bwt/day) on intravenous administration in rats regularly for 28 days. The study was performed based on the OECD test guideline 407. No clinical signs and mortalities were observed in any groups of rat treated with AuNP. No evidence of toxicity was observed in any of the diverse studies performed which is noteworthy. The study includes survival, behavior, animal weight, organ morphology, blood biochemistry and tissue histology. The results indicate that tissue accumulation pattern of gold nanoparticles depends on the surface, size and doses of the nanoparticle. The accumulation of the particles does not produce subacute physiological damage.

MICROWAVE-ASSISTED RAPID BIOSYNTHESIS OF STABLE SILVER NANOPARTICLES USING CLOVE BUDS (SYZYGIUM AROMATICUM) SOLUTION

This is an extended work on the biosynthesis of noble metal nanoparticles using dried clove buds. Here microwave assistance is taken not only for accelerating the reaction rate but also for denaturing the proteins and other enzymes, which will prevent obtaining desired functionalized nanoparticles. FTIR studies infer that nanoparticles thus obtained are found adsorbed with water soluble organic moieties, mostly flavonoids. The bathochromic shift from 320 nm in ultra-violet range indicates the involvement of water soluble bio-moieties of the clove in the formation of AgNP. X-ray diffraction (XRD) spectrum confirmed that the AgNP are crystalline in nature. The surface morphology is studied using FESEM, TEM and AFM techniques infer that the AgNP are well dispersed, roughly spherical in shape and are in the range of 30–60 nm. The AgNP with the organic moiety will have synergic antimicrobial action.

Nanobiotechnology in the Health Care: The Game and the Goal

Nanomedicine plays an important role in the future advances of analytical and therapeutic methods. There are various methods to synthesize nanoparticles like biological, physical, and chemical. Nanomaterials are important materials used extensively to study its applications in therapeutic medicines, sensing, optoelectronic, molecular imaging and catalysis, etc. In recent years, nanotechnology has modernized the progress in developing the biological sensors. Nanobiosensor research focuses on the development of innovative technologies for significant contributions in the fields of detection of human and animal diseases. Nanomedicine attempts innovative solutions like glucose sensors, artificial pancreas, biodegradable nanocarriers, and oral delivery of insulin in treating diabetes mellitus. The cardiovascular nanoimaging is a simple diagnosis that helps in real-time tracking during surgery and treatment. Biofunctionalized nanoparticles are under extensive progress for the development of nanomaterial-based drugs and cancer detection. The study deals with the promising complex identification and analysis and treatment of various diseases. The size, shape, stability, and surface characteristics make nanoparticles more attractive and compatible in various fields. This chapter discusses briefly different practices of nanoparticles in important and vast medical areas.

In vivo efficacy of biocompatible silver nanoparticles cream for empirical wound healing

Wound healing is a complicated process that begins at the onset of injury and a continued process till complete healing. The emergence of nanotechnology has provided a new therapeutic modality to silver nanoparticles in treatment of wounds. However, the safety of these silver nanoparticles in the process of wound healing is yet to be elucidated; nevertheless, biocompatibility is the primary concern. Biosynthesis of silver nanoparticles was synthesized using aqueous clove extract and silver nitrate solution under microwave and the obtained particles size were 30-60 nm and roughly spherical in shape. The present study focused on the efficacy of biocompatible silver nanoparticles in vivo wound healing process. Consequently, this study supported the incorporation of biosynthesized silver nanoparticles in wound dressings as a cream formulation for improved healthcare.