Biosensors And Bioelectronics Template

The present work encompasses a  novel combined approach of electrostatic functionalization  and thermally embedding of graphene oxide (GO) on a flexible substrate to fabricate a highly sensitive and selective amperometric lactate biosensor. GO was functionalized by non-chemical and dry-process using corona discharge tube method, i.e., electrostatic approach to yield oxygenated functional groups on their surfaces and transferred onto flexible substrate by thermal embedding technique, which acts as a working electrode. Commercial, lactate oxidase from Pediococcus species has been immobilized through glutaraldehyde coupling onto the surface of working electrode. The electrocatalytic activity of the modified electrodes towards lactic acid was investigated using amperometric technique. The enzyme electrode showed good electrocatalytic activity and optimum response when operated at 35oC in 0.05M sodium phosphate buffer at 0.4 V. A linear response with the lactic acid concentration range from 0.1 to 6mM/L and a high sensitivity of 0.1202 μA/mM/l with a detection limit of 0.1mM/L was observed. The serum values in healthy and diseased persons were in the range of 0.5-2.4 and 4.4mM to 8mM, respectively. The analytical recovery of added lactic acid was 84%. The biosensor sustained its stability for more than 25 days with 150 times of reusage without considerable loss of activity, when stored at 40C. The electrode significantly provides long term stability and highly reproducible detection of a key metabolite lactate in serum.
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L-lactate is an indispensable metabolite formed during anaerobic metabolism of glucose in muscles followed by a surge of proton concentration into the cell. An elevated lactate production results in decreased cellular pH leads to the cell acidosis and are indicative of various ischemic conditions including shock, heart stroke, respiratory insufficiencies, liver diseases and tissue hypoxia. Various commercial and analytical methods i.e., colorimetric tests, electrophoresis1 and spectrophotometric2 analysis are available for the detection of the key metabolite, L-lactate. Amongst all, biosensors have been the best suited devices for biochemical analysis due to their good stability, high sensitivity with reproducible results. Thus, the innate need of biosensor is extensively important for the current health-care applications for continuous real time monitoring of patients at close proximity3.  In addition to this, the intervention of nanotechnology and emergence of nanomaterials for the fabrication of biosensors has also gained a worldwide attention in recent years4, 5 for various electrochemical sensor and biosensor applications by virtue of their unique physical and chemical properties like small size and larger surface area to volume ratio with high conductivity6.