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Raghu P.,Sri Venkateswara University | Mohan Reddy M.R.,Sri Devaraj Urs Acedamy of Higher Education and Research SDUAHER | Reddy T.M.,Sri Venkateswara University | Kumara Swamy B.E.,Kuvempu University | Reddaiah K.,Sri Venkateswara University
Analytical and Bioanalytical Electrochemistry | Year: 2012

Acetylcholinesterase (AChE) was an important cholinesterase enzyme present in the living organisms, which is responsible for transmission of impulses through synaptic clefts by oxidation of acetylcholine to choline. Acetylcholinesterase enzyme was immobilized through silica sol-gel process on the surface of carbon paste electrode which was used to fabricate monoenzyme biosensor. It is a rapid, simple and sensitive biosensor used for determination of two organophosphorous pesticides monocrotophos and phosphamidon in 0.1 M phosphate buffer and in 0.1 M KCl. Acetylthiocholine chloride (ASChCl) was used as substrate by enzymatic hydrolysis it gives thiocholine which undergone electrochemical oxidation and produces anodic current around at 0.60 V vs. saturated calomel electrode. The effect of scan rate, pH, enzyme loading and substrate concentration on the biosensor response was studied. The biosensor provided a high sensitivity, large linear concentration range from 50-900 ppb, 0.1-1.25 ppm for monocrotophos and phosphamidon. The detection limits were found to be 45 ppb, 0.06 ppm for monocrotophos and phosphamidon respectively. The results showed the optimum conditions for pH, substrate concentration, and incubation time were at room temperature, pH 7.0, 1 mM, 4 and 3 min for monocrotophos and phosphamidon respectively. © 2012 by CEE. Source


Reddaiah K.,Sri Venkateswara University | Reddy M.M.,Sri Devaraj Urs Acedamy of Higher Education and Research SDUAHER | Raghu P.,Sri Venkateswara University | Reddy T.M.,Sri Venkateswara University
Colloids and Surfaces B: Biointerfaces | Year: 2013

In this paper, the carbon paste electrode (CPE) was modified with poly- Solochrome dark blue (poly-SDB), through polymerization process, and it was used for the sensitive and selective determination of dopamine (DA). The simultaneous determination of Dopamine (DA) Ascorbic acid (AA) and Uric acid (UA) in 0.1. M Phosphate buffer solution (PBS) of pH 6.0 was carried out by employing differential pulse voltammetric technique (DPV). The effect of pH, concentration, scan rate, accumulation time, repetability and reproducibility of DA was studied at poly-SDB film modified electrode. The poly-SDBCPE exhibited a strong electrocatalytic action toward the oxidation of DA, AA and UA. The overlapping voltammetric response of biomolecules separated in to three well defined peaks with lower oxidation potential and significant increase in the anodic peak currents in the presence of poly-SDBCPE was achieved. The results showed a good sensitivity, selectivity and high reproducibility of electro synthesized polymer electrode. The limit of detection, limit of quantification and correlation coefficient of DA at poly-SDBCPE was 0.8. μM, 2.8. μM and 0.99765 respectively. The effect of interference was studied by DPV technique. The developed modified electrode was used for the analysis of DA in pharmaceutical formulations with satisfactory results. The interfacial electron transfer behavior of DA was studied by electrochemical impedance spectroscopy (EIS) and results showed that the charge transfer rate was enhanced at poly- SDBCPE, when compared with bare CPE, glassy carbon electrode (GCE) and platinum electrode (Pt). © 2013 Elsevier B.V. Source


Narayana P.V.,Sri Venkateswara University | Madhusudana Reddy T.,Sri Venkateswara University | Gopal P.,Sri Venkateswara University | Mohan Reddy M.,Sri Devaraj Urs Acedamy of Higher Education and Research SDUAHER | Ramakrishna Naidu G.,Sri Venkateswara University
Materials Science and Engineering C | Year: 2015

Abstract The present paper describes the new strategy for the development of nanosensor based on dropcasting of multi-walled carbon nanotubes (MWCNTs) followed by electropolymerization of serine (ser) onto the glassy carbon electrode (GCE). The developed nanocomposite sensor was abbreviated as poly(ser)/MWCNTs/GCE and was characterized by using electrochemical impedance spectroscopy (EIS) technique. The EIS results confirmed the fast electron transfer rate at the surface of poly(ser)/MWCNTs/GCE. The proposed sensor exhibited good catalytic activity towards the sensing of epinephrine (EP) individually and simultaneously in the presence of serotonin (5-HT) and folic acid (FA) in 0.1 M phosphate buffer solution (PBS) at pH 7.0. The limit of detection (LOD) and limit of quantification (LOQ) of EP was found to be 6 × 10-7 M and 2 × 10-6 M respectively. The fabricated sensor showed excellent precision and accuracy with a relative standard deviation (RSD) of 4.86%. The proposed composite sensor was effectively applied towards the determination of EP in human blood serum and pharmaceutical injection sample. © 2015 Elsevier B.V. Source


Reddaiah K.,Sri Venkateswara University | Madhusudana Reddy T.,Sri Venkateswara University | Reddy M.M.,Sri Devaraj Urs Acedamy of Higher Education and Research SDUAHER | Raghu P.,Sri Venkateswara University
Sensor Letters | Year: 2013

The electrochemical behaviour of L-dopa (3,4-dihydroxy L-phenylalanine) was studied in a sensitive and selective manner through the surface modification with a poly-Xylene cyanol FF (poly-XCyFF) film on the carbon paste electrode (CPE) by employing voltammetric techniques. The modified electrode exhibited good promotion of electrocatalytic action towards the electrochemical investigation of L-dopa in 0.1 M phosphate buffer solution (PBS) of pH 5.0. Poly-XCyFFMCPE was found to exhibit good resolution and response towards the simultaneous determination of L-dopa in the presence of high concentration of ascorbic acid (AA) and uric acid (UA) in PBS. The effect of pH, scan rate, preconcentration time and concentration of L-dopa was studied at the fabricated polymer film electrode. The voltammetric peak currents showed a linear relation of L-dopa concentration in the range from 20×10-6 M to 9×10-3 M, with a detection limit of 1.8 μM, quantification limit of 6.0 μM and correlation coefficient of 0.9925 respectively. The poly-XCyFFMCPE was successfully applied towards the determination of L-dopa in pharmaceutical formulation. The electron transfer kinetics of redox probe at poly-XCyFFMCPE was studied by employing electrochemical impedance measurement. In conclusion this study illustrated that the proposed electrode modified with XCyFF is of high sensitive, more accurate, good precision and suitable for selective determination of L-dopa in comparison with bare CPE. © 2013 American Scientific Publishers. Source


Raghu P.,Sri Venkateswara University | Mohan Reddy M.,Sri Devaraj Urs Acedamy of Higher Education and Research SDUAHER | Madhusudana Reddy T.,Sri Venkateswara University | Kumara Swamy B.E.,Kuvempu University | Reddaiah K.,Sri Venkateswara University
Analytical and Bioanalytical Electrochemistry | Year: 2013

Acetylcholinesterase (AChE) enzyme was immobilized through the silica sol-gel process onto the surface of carbon paste electrode (CPE). This fabricated monoenzyme biosensor on CPE was used as a working electrode. The enzyme biosensor on reaction with acetylthiocholine chloride (ASChCl or substrate), was found to be enzymatically hydrolyzed to thiocholine and acetic acid, which intern gave a disulfide compound and produced a larger anodic current at 0.63 V. The AChE biosensor was used for determining the two organophosphorous pesticides i.e. quinalphos and malathion in 0.1 M phosphate buffer/0.1 M KCl. The effect of scan rate, pH, enzyme loading and substrate concentration on the biosensor response was studied. Calibration graphs were performed for a concentration range of 20-300 ppb and 0.07-1.3 ppm for quinalphos and malathion respectively by employing the fabricated biosensor electrode. The limit of detection and limit of quantification values was found to be 8 ppb, 0.058 ppm and 26 ppb, 0.194 ppm for quinalphos and malathion respectively. © 2013 by CEE. Source

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