Chandrasekaran N

Electronics

School of Electronics Engineering

Chennai Campus

Amitava Mukherjee

Centre for Nanobiotechnology

Vellore Campus

Ida evangeline paul

D nanda kumar

A rajeshwari

Sruthi ann alex

D karthiga

Ashok m raichur

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Nanobiosensors

Detection of food contaminants by gold and silver nanoparticles

A simple rapid method was developed using gold nanorods for the colorimetric detection of lipopolysaccharide extracted from the generic strain, E. coli K12, which was used as a surrogate for the pathogenic strain, E. coli O157:H7. The principle is based on the aggregation of the cetyltrimethylammonium bromide-capped gold nanorods in the presence of lipopolysaccharide dispersed in phosphate buffer (pH 7.2). The interaction of the gold nanorods caused a rapid colour change from blue to black, which was visible through naked eye. The colour change was accompanied by a decrease in the absorbance of the longitudinal surface plasmon resonance (691 nm) of gold nanorods in the UV-visible spectra. The transmission electron microscopy confirmed the interaction of the gold nanorods with lipopolysaccharide. A good linearity (correlation coefficient R2 = 0.9725) was obtained between the concentration of lipopolysaccharide and absorbance ratio A/A0 of gold nanorods for the lipopolysaccharide concentration ranging from 200 ng/ml to 5 ng/ml. The limit of detection of the developed probe was found to be 1.11 ng/ml. Further, the developed probe was successfully employed in the detection of lipopolysaccharide spiked in food products like apple juice, mango juice, liquid milk, milk powder, and raw milk, and a good recovery percentage of 97%-106% was observed. © 2016 American Scientific Publishers.

Sensor Letters

Label-Free Colorimetric Detection of Bacterial Lipopolysaccharide in Food Samples Using Gold Nanorods

A simple colorimetric detection of melamine was studied using 15 nm (AuNPs-I), 30 nm (AuNPs-II), and 40 nm (AuNPs-III) citrate-capped gold nanoparticles (AuNPs).

Analytical Methods

Colorimetric detection of melamine based on the size effect of AuNPs

In the present study, silver nanoparticles were rapidly synthesized at room temperature by treating silver ions with the Citrus limon (lemon) extract. The effect of various process parameters like the reductant concentration, mixing ratio of the reactants and the concentration of silver nitrate were studied in detail. In the standardized process, 10(-2)M silver nitrate solution was interacted for 4h with lemon juice (2% citric acid concentration and 0.5% ascorbic acid concentration) in the ratio of 1:4 (vol:vol). The formation of silver nanoparticles was confirmed by Surface Plasmon Resonance as determined by UV-Visible spectra in the range of 400-500 nm. X-ray diffraction analysis revealed the distinctive facets (111, 200, 220, 222 and 311 planes) of silver nanoparticles. We found that citric acid was the principal reducing agent for the nanosynthesis process. FT-IR spectral studies demonstrated citric acid as the probable stabilizing agent. Silver nanoparticles below 50 nm with spherical and spheroidal shape were observed from transmission electron microscopy. The correlation between absorption maxima and particle sizes were derived for different UV-Visible absorption maxima (corresponding to different citric acid concentrations) employing "MiePlot v. 3.4". The theoretical particle size corresponding to 2% citric acid concentration was compared to those obtained by various experimental techniques like X-ray diffraction analysis, atomic force microscopy, and transmission electron microscopy.

Colloids and Surfaces B: Biointerfaces

Biomimetic synthesis of silver nanoparticles by Citrus limon (lemon) aqueous extract and theoretical prediction of particle size

Biofunctionalization of noble metal nanoparticles like Ag, Au is essential to obtain biocompatibility for specific biomedical applications. Silver nanoparticles are being increasingly used in bio-sensing applications owing to excellent optoelectronic properties. Among the serum albumins, the most abundant proteins in plasma, a wide range of physiological functions of Bovine Serum Albumin (BSA) has made it a model system for biofunctionalization. In absence of adequate prior reports, this study aims to investigate the interaction between silver nanoparticles and BSA. The interaction of BSA [0.05-0.85% concentrations] with Ag nanoparticles [50 ppm concentration] in aqueous dispersion was studied through UV-vis spectral changes, morphological and surface structural changes. At pH 7, which is more than the isoelectric point of BSA, a decrease in absorbance at plasmon peak of uninteracted nanoparticles (425 nm) was noted till 0.45% BSA, beyond that a blue shift towards 410 nm was observed. The blue shift may be attributed to enhanced electron density on the particle surfaces. Increasing pH to 12 enhanced the blue shift further to 400 nm. The conformational changes in BSA at alkaline pH ranges and consequent hydrophobic interactions also played an important role. The equilibrium adsorption data fitted better to Freundlich isotherm compared to Langmuir curve. The X-ray diffraction study revealed complete coverage of Ag nanoparticles by BSA. The scanning electron microscopic study of the interacted nanoparticles was also carried out to decipher morphological changes. This study established that tailoring the concentration of BSA and pH of the interaction it was possible to reduce aggregation of nanoparticles. Biofunctionalized Ag nanoparticles with reduced aggregation will be more amenable towards bio-sensing applications. © 2009 Elsevier B.V. All rights reserved.

Studies on interaction of colloidal Ag nanoparticles with Bovine Serum Albumin (BSA)

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