Sonal Thakore

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.

Magnetically separable core–shell iron oxide@nickel nanoparticles as high-performance recyclable catalysts for chemoselective reduction of nitroaromatics

A magnetically separable core–shell iron oxide@nickel (IO@Ni) nanocatalyst was synthesized by reduction of Ni2+ ions in the presence of iron oxide (Fe2+, Fe3+) by a simple one-pot synthetic route using NaBH4 as a reducing agent and starch as a capping agent. The synthesized nanoparticles (NPs) were characterized by several techniques such as X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), and energy dispersive X-ray spectroscopy (EDS). The core–shell iron oxide@nickel nanoparticles (IO@NiNPs) were found to have excellent activity for the hydrogenation reactions of aromatic nitro compounds under mild conditions using water as a green solvent. Excellent chemoselectivity and recyclability up to 30 cycles for the nitro group reduction was demonstrated.

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.

Cellulose crosslinked pH-responsive polyurethanes for drug delivery: α-hydroxy acids as drug release modifiers.

Cellulose crosslinked waterborne polyurethanes (PUs) based on poly ɛ-caprolactone with lactic acid/glycolic acid/dimethylol-propionic acid as a drug release modifiers cum chain extenders were prepared. PUs were loaded with felodipine and drug release was monitored at different pH values. The structure of the polymers was characterized by FTIR, DSC & TGA and SEM. The encapsulation of dug inside PU matrix and the morphology of polymer after drug release were studied by using SEM. All the PUs were observed to degrade under highly basic conditions. The PUs act as pH sensitive drug carriers with an added advantage of modulated release rate as a function of acid chain extenders. The rate of release of the drug was significantly faster at pH 7.4 as compared to gastric pH 1.2, with same incubation time. The PUs reported in the present study may be suitable for medical applications like vaginal drug delivery and colon specific drug delivery.

Structure-property relationships and biocompatibility of carbohydrate crosslinked polyurethanes.

Biocompatible and biodegradable polyurethanes (PUs) based on castor oil and polypropylene glycols (PPGs) were prepared using various carbohydrate crosslinkers: monosaccharide (glucose), disaccharide (sucrose) and polysaccharides (starch and cellulose). The mechanical and thermal properties were investigated and interpreted on the basis of SEM study. The advantage of incorporating various carbohydrates is to have tunable mechanical properties and biodegradability due to variety in their structure. The glass transition temperature and sorption behavior were dominated by the type of polyol than by the type of crosslinker. All the PUs were observed to be biodegradable as well as non-cytotoxic as revealed by MTT assay in normal lung cell line L132. The study supports the suitability of carbohydrates as important components of biocompatible PUs for development of biomedical devices.

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.

Sunflower oil mediated biomimetic synthesis and cytotoxicity of monodisperse hexagonal silver nanoparticles.

In this work, sunflower oil was utilized for the biomimetic synthesis of silver (Ag) nanoparticles (NPs), leading to highly mono-dispersed hexagonal-shaped silver nanoparticles (NPs) at various concentrations. It was found that the biomolecules of the oil not only have the capability to reduce silver ions, due to its extended phenolic system, but also appear to recognize and affect the Ag nanocrystal growth on the (110) face, leading to hexagonal growth of the NPs of 50 nm size. Initially, some spherical AgNPs of less than 10nm diameter were observed; however, over a longer period of time, a majority of hexagonal-shaped nanocrystals were formed. The one step synthesis can be extended for other metals. The as prepared sunflower oil capped AgNPs being completely free of toxic chemicals can be directly utilized for in vitro studies and offer a more rational approach for cellular applications. The NP solution exhibited dose-dependent cytotoxicity in human lung carcinoma cells and physiologically relevant cell model (3T3L1 cells).