Development of nanobiosensors as freshness indicator for meat and fish

The main objective of this study is development of an amperometric based electrochemical enzyme nanobiosensor to determine the freshness of meat and fish. First, 2cm long gold wire of 99.9% purity was dissolved in royal water (aqua regia: HCl+3HNO3) acid solution. Then, [AuCl4]-(aq) solution was reduced with C6H5O7.2H2O.3Na (tri-Sodium citrate dihydrate) salt to produce (~50 nm) gold (Au) nanoparticles. Prior to coating of nanopowders on a pencil graphite working electrode (PGE), pyrolle monomer and hydrochloric acid were used to form a conductive composite film. Au nanoparticles were coated on PGE electrode by using potentiostat-galvanostat device based on the cyclic voltammetry method with applied potential values between -0,3 and +0,8 V, at a scanning rate of 0,1 V/s with 13 cycles. A xanthine oxidase (XOD) enzyme was immobilized with 5% glutaraldehyde on the coated PGE/PPy-Au electrode as biosensing agent. To characterize this immobilization, electrochemical impedimetric analysis (EIS) methods were used. To determine the working range of the biosensor, measurements were performed at different values of pH, temperature, and substrate concentrations. Amperometric method was used for the measurement of Xanthine (X). Based on the results obtained in this study, enyzme biosensing methods were compared with classical methods and performance characteristics have been reported.