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Nithyaja B.,Cochin University of Science and Technology | Nithyaja B.,Sree Narayana College for Women | Vishnu K.,Cochin University of Science and Technology | Mathew S.,Cochin University of Science and Technology | And 2 more authors.
Journal of Applied Physics | Year: 2012

This paper discusses band gap tunability of CdS nanoparticles in biotemplates deoxyribonucleic acid (DNA) and bovine serum albumin (BSA). DNA is more efficient in controlling the size of the nanoparticles compared to BSA. Since nanoparticles are capped with biomaterials, they are very useful for biolabeling. The photo luminescence spectrum of CdS nanoparticles in DNA template shows sharp emission peak at 490 nm with shoulders at 430 nm and 530 nm while that of CdS in BSA template has emission peak at 530 nm with shoulders at 477 nm and 410 nm. The excitation wavelength dependent shift of photoluminescence peak is found to be between 40 and 50 nm for a change in excitation wavelength from 260 to 420 nm. We also studied excitation wavelength dependence on fluorescence emission of CdS nanoparticles stabilized with DNA and BSA. © 2012 American Institute of Physics. Source

Mary Nancy T.E.,Sree Narayana College for Women | Anithakumary V.,Sree Narayana College for Women | Kumara Swamy B.E.,Kuvempu University
Journal of Electroanalytical Chemistry | Year: 2014

Graphene was synthesized by solar exfoliation method. A glassy carbon electrode (GCE) modified with solar graphene (sG), was used for resolving the voltammetric signals of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The excellent resolution of the signals was due to the presence of edge planes and oxygenated defects in sG; which were confirmed by Raman and Fourier transform infrared (FTIR) spectra. This enabled the simultaneous detection of AA, DA and UA in 0.1 M phosphate buffer solution at the physiological pH. The sensor exhibited good stability, sensitivity and selectivity towards the analysis of the three components in their mixtures. Selective detection of DA using sG/GCE is also presented.© 2014 Elsevier B.V. All rights reserved. Source

Nancy T.E.M.,Sree Narayana College for Women | Kumary V.A.,Sree Narayana College for Women
Electrochimica Acta | Year: 2014

A novel solar graphene-nickel hydroxide modified glassy carbon electrode was developed and used for the simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The sensor exhibited appreciable electrocatalytic effect for the simultaneous detection of lower concentrations of the analytes compared to solar graphene modified glassy carbon electrode. The detection limits attained by differential pulse voltammetry (DPV) were 30 μM, 120 nM and 0.46 μM for AA, DA and UA respectively. Recovery values ranging from 98 - 104% were obtained for the analysis of real samples. © 2014 Elsevier Ltd. Source

Anitha Kumary V.,Sree Narayana College for Women | Mary Nancy T.E.,Sree Narayana College for Women | Divya J.,Sree Narayana College for Women | Sreevalsan K.,Sree Narayana College
International Journal of Electrochemical Science | Year: 2013

Graphene based sensors receive attention due to their enhanced surface area, unique two-dimensional structure, remarkable stability and excellent electrical conductivity. In the present work graphene-nickel/nickel oxide composite was prepared via solar exfoliation of graphite oxide/nickel acetate precursor. The morphology and structure of the as prepared composite has been characterized by transmission electron microscopy (TEM) & X-ray diffraction (XRD) techniques. The composite was used to modify the glassy carbon electrode surface. Its electrocatalytic activity for the oxidation of glucose in alkaline medium was investigated by cyclic voltammetry. The sensitivity and selectivity of the modified electrode towards glucose oxidation promises its effectiveness as a nonenzymatic glucose sensor for practical applications. © 2013 by ESG. Source

Vidyadharan A.K.,Sree Narayana College for Women | Jayan D.,Sree Narayana College for Women | Mary Nancy T.E.,Sree Narayana College for Women
Journal of Solid State Electrochemistry | Year: 2014

A novel electrochemical sensor based on nickel-doped cobalt ferrite nanoparticles (Ni0.1Co0.9Fe2O 4)-modified glassy carbon electrode (NCF/GCE) was presented for the sensitive detection of paracetamol. Experimental conditions such as pH, applied potentials and concentration were investigated using cyclic voltammetric and chronoamperometric techniques. The modified electrode exhibited excellent catalytic response towards the oxidation of paracetamol with good reproducibility. The overpotential for oxidation of paracetamol is decreased, and the current response enhanced significantly on the modified electrode in comparison with that of bare electrode. Linear calibration curve is obtained over the range 2 μM to 8,000 μM having a detection limit of 11 nM. The modified electrode facilitated the simultaneous detection of paracetamol, ascorbic acid, and dopamine with good reproducibility. © 2014 Springer-Verlag Berlin Heidelberg. Source

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