Uricase grafted nanoconducting matrix based electrochemical biosensor for ultrafast uric acid detection in human serum samples

Gold nanoparticles decorated graphene oxide (Au-rGO) nanocomposite thin films with enhanced electro-active characteristics were prepared and covalently immobilized with uricase (U0x) enzyme for sensitive and selective detection of uric add (UA). Differential pulse voltammetry (DPV) studies revealed rapid response of fabricated electrode towards UA at low potential (0.228 V) in a wide concentration range of 50 similar to 800 mu M with a sensitivity of 86.62 +/- 0.19 mu A mM(-1) and very low detection limit of 732 +/- 021 mu M. The obtained Michaelis-Menten constant (k(m)) value of 51.75 mu m signifies high enzyme kinetics at electrode surface with UA. The developed biosensor was successfully applied to detect UA in human serum samples. Interferences due to components present in the real matrix were evaluated and UA determination in mixed sample was also performed. The fabricated UOx/Au-rGO/ITO biosensor demonstrated high reproducibility and a shelf-life of 6 months indicating the promising future of Au-rGO nanocomposite as an efficient transducer matrix for biosensing applications. The fast response time (1.0 +/- 0.6 s) and improved sensor performance is attributed to the synergistic electronic properties of Aunanoparticles and rGO that provided enhanced electron transfer and high electro-active species surface coverage at Au-rGO nanocomposite. (C) 2019 Elsevier B.V. All rights reserved.