Mayur Valodkar

Morphology and antibacterial activity of carbohydrate-stabilized silver nanoparticles

Silver nanoparticles were prepared by a simple hydrothermal route and chemical reduction using carbohydrates (sucrose, soluble and waxy corn starch) as reducing as well as stabilizing agents. The crystallite size of these nanoparticles was evaluated from X-ray diffraction (XRD) and transmission electron microscopy (TEM) and was found to be 25nm. The effect of carbohydrates on the morphology of the silver nanocomposites was studied using scanning EM (SEM). The nanocomposites exhibited interesting inhibitory as well as bactericidal activity against both Gram positive and Gram negative bacteria. Incorporation of silver also increased the thermal stability of the carbohydrates.

Cytotoxicity evaluation and antimicrobial studies of starch capped water soluble copper nanoparticles

Water soluble monodisperse copper nanoparticles of about 10nm diameter were prepared by microwave irradiation using starch as green capping agent. The resulting Cu-starch conjugate were characterized by FTIR and energy dispersive X-ray analysis (EDX). The study confirmed the presence of copper embedded in polysaccharide matrix. The aqueous solution of starch capped copper nanoparticles (SCuNPs) exhibited excellent bactericidal action against both gram negative and gram positive bacteria. The in vitro cytotoxicity evaluation of the nanoparticles was carried out using mouse embryonic fibroblast (3T3L1) cells by MTT cell viability assay, extracellular lactate dehydrogenase (LDH) release and dark field microscopy imaging. The capped nanoparticles exhibited cytotoxicity at much higher concentration compared to cupric ions. Minimum bactericidal concentration (MBC) of SCuNPs was well below the in vitro cytotoxic concentration. Statistical analysis demonstrated p<0.05 for significant results and p>0.05 for non-significant ones as compared to untreated cells. The non-cytotoxic green Cu-starch conjugate offers a rational approach towards antimicrobial application and for integration to biomedical devices.

Isocyanate crosslinked reactive starch nanoparticles for thermo-responsive conducting applications

Hydrophobic nanoparticles and nanocomposite films of 1,4-hexamethylene diisocyanate (HMDI)-modified starch nanoparticles (SNPs) have been synthesized at ambient temperatures. The platelet-like starch nanocrystals become pseudospherical after modification with HMDI and the size increases or decreases depending on diisocyanate concentration compared to the ungrafted particles as revealed by transmission electron microscopy (TEM) results. The obtained nanocrystals were characterized by means of the FT-IR and X-ray diffraction (XRD) techniques. When compared with the hydrophobic performance of the unmodified starch nanocrystals, that of crosslinked starch nanocrystals significantly increased. X-ray diffraction reveals that the crystalline structure of modified starch nanocrystals was preserved. The resulting hydrophobic starch nanoparticles are versatile precursors to the development of nanocomposites. The polyether-polyurethane crosslinked with SNPs nanocomposite film exhibited thermo-responsive electrical conductivity.

Oxidative stress induced apoptosis of human lung carcinoma (A549) cells by a novel copper nanorod formulation

This study elucidates the process of synthesis of copper (Cu) nanorods using almond skin extract as stabilizing cum capping agent. These nanorods were (about 200 nm long and 40 nm wide) characterized by transmission electron microscopy (TEM). Further, cytotoxicity potential of these nanorods was evaluated in A549 cells (Human lung carcinoma cell line) via cell viability assay and extracellular lactate dehydrogenase (LDH) release. Also, reduced glutathione (GSH), lipid peroxidation (LPO), cellular oxidative stress (Rhodamine 123 florescence) and apoptosis (Annexin V FITC/Propidium iodide staining) were also investigated in control and treated cells. Results indicated that Cu nanorods induced apoptotic death of cancer cells by induction of oxidative stress, depletion of cellular antioxidants and mitochondrial dysfunction. This study reports a novel process of synthesis of almond skin extract capped Cu nanorods and its potential as an anticancer agent against A549 lung carcinoma cells.

Conducting and Antimicrobial Properties of Silver Nanowire–Waxy Starch Nanocomposites

ABSTRACT Silver nanowires were prepared on a waxy corn starch matix by a simple and green hydrothermal route. Infrared (IR) spectroscopy and X-ray diffraction (XRD) confirmed the presence of nanostructured cubic silver embedded in waxy starch matrix. The particle size by Scherrer’s equation is calculated to be about 32 nm. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) revealed a uniform morphology, indicating intimate association of the metal-polysaccharide composite. The nanocomposites exhibited bactericidal effect and electrical conductivity, which was observed to be a function of temperature and metal concentration. The eco-friendly nanocomposites could be of potential biomedical application.

Thermal and Mechanical Properties of Natural Rubber and Starch Nanobiocomposites

Large-scale starch nanoparticles of about 10–50 nm were obtained by acidic hydrolysis of amylopectin-rich cornstarch (waxy starch). They were used to prepare nanobiocomposites with natural rubber by mastication technique. Up to 30 phr (parts per hundred of rubber) of the filler was successfully incorporated leading, to an enhancement in thermo-mechanical properties. Tensile and elongation were even higher than those of conventional composites of untreated waxy starch and amylose-rich starch as well as carbon black at all loadings. SEM revealed single-phase morphology of nanocomposites, indicating extremely uniform mixing. It was observed that starch could be a potential substitute for carbon black as filler.

Synthesis and cytotoxicity evaluation of novel acylated starch nanoparticles.

Starch nanoparticles (StNPs) were acylated under ambient conditions to obtain various nanosized derivatives formed stable suspension in water and soluble in organic solvents. The degree of substitution (DS) was determined using (1)H NMR technique. The cytotoxicity potential of the derivatised StNPs was evaluated in mouse embryonic fibroblast (3T3L1) cells and A549 tumor cell line using MTT cell viability assay. Other parameters that determine the oxidative stress viz., reactive oxygen species (ROS) generation, intracellular reduced glutathione (GSH), superoxide generation and acridine orange/ethidium bromide staining were also investigated. The present study led to the conclusion that cytotoxic activity of acylated starch nanoparticles was dependent on their dosage, DS and type of substitution. The non-toxic nature in non-cancerous cells reveals that the nanoparticles (NPs) can be used for cancer therapy and drug delivery. The nanoparticles also offered reasonable binding propensity with CT-DNA.

Polymer Nanocomposites for Energy and Fuel Cell Applications

This chapter provides an overview on the clay- and carbon-based polymer nanocomposites for fuel cell (FC), Li-ion battery, and supercapacitor (SC) applications. Fuel cell is responsible for conversion of chemical energy into electrical energy, whereas Li-ion battery and supercapacitor are mainly responsible for energy storage applications. Here, the applications of nanocomposite membranes for fuel cell application followed by Li-ion battery and supercapacitor applications are described. The working principle, purpose, and physical properties of the nanocomposites are critically described for the aforementioned applications. Finally, the summary and future scopes of the polymer nanocomposites in these fields are described.