Journal of Biotechnology & Biomaterials
Open Access

Abstract

Gold nano-particles have been known for their excellent biological compatibility, unique physico-chemical properties. Nano-structured gold has been used in recognition of biological events, facilitating better electronic signal transduction, leading to new generation of bio-electronic devices. We have fabricated gold nano aggregates (GNAs) based electrode via direct electrodeposition method onto indium tin oxide coated glass plates for its application towards development of electrochemical DNA biosensor for early detection of Typhoid. GNP-A/ITO electrode was characterized using X-Ray diffraction that reveals the deposition of metallic gold nano particles in fcc structure. The GNAs/ITO electrode exhibited good electro-analytical activity and shows quasi-reversible behaviour. GNAs/ITO electrode was modified with self assembled monolayer of 11-Mercaptoundecanoic acid (MUA) to immobilize amine modified ssDNA probe for fabrication of ssDNA/MUA/GNAs/ITO bio-electrode. Response studies of the ssDNA/MUA/GNAs/ITO bio-electrode towards target probes were done using differential pulse voltammetry (DPV) by monitoring direct guanine oxidation and with ethylene blue (MB) as redox indicator. Direct monitoring of guanine oxidation with complementary targets on ssDNA/MUA/GNP-A/ITO bio-electrode, limit of detection was found upto 150 ottomol whereas Methylene blue redox indicator exhibited improved limit of detection upto 4 ottomol at 25?C in phosphate buffer with in 60 s hybridization time. The bioelectrode shows 37 times enhanced sensitivity and was found efficiently able to distinguish complementary, non-complementary and one base mismatch target. This biosensor electrode has implications towards detection of other pathogens like M. tuberculosis, Campylobacter, H. Pylori, E. coli etc for clinical diagnostics, food quality control and environmental monitoring.

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