Protein capped Cu nanoclusters-SWCNT nanocomposite as a novel candidate of high performance platform for organophosphates enzymeless biosensor

A biocompatible nanocomposite including bovine serum albumin (BSA) template Cu nanoclusters (CuNCs@BSA) and single-walled carbon nanotubes (SWCNT) was synthesized to fabricate a highly sensitive electrochemical biosensor for paraoxon as a model of organophosphates. The UV-vis, fluorescence and Fourier transform infrared (FTIR) demonstrated that BSA entrapped in the nanocomposite film have been changed in its secondary structure so that it provided an enzyme like activity attributing to the high electrical conductivity of the entrapped copper nanoclusters. Also, the morphology and structure of prepared nanocomposites were investigated by transmission electronic microscopy (TEM) and scanning electron microscopy (SEM). In the prepared nanocomposite, the CuNCs@BSA found to play as a conductive holder as well as an accumulator of redox active centers on the surface of the electrode, and SWCNT improves the electrocatalytic activity along with conductivity of glassy carbon electrode (GCE) surface. The fabricated biosensor exhibited excellent sensitivity, acceptable stability, fast response, and high electrocatalytic activity toward the reduction of paraoxon. The reduction peak current vs paraoxon concentration was linear over the range 50 nM to 0.5 μM and 0.5-35 μM, with a limit of detection of 12.8 nM. Notable electrocatalytic properties of the developed electrode toward paraoxon indicated that the nanocomposite possesses a promising potential to fabricate the third generation enzyme-free electrochemical biosensors, bioelectronics and state-of-the-art biomedical devices in the future.