Ultrasmall CuS-BSA-Cu(PO) nanozyme for highly efficient colorimetric sensing of HO and glucose in contact lens care solutions and human serum.

This work reports on the synthesis of organic-inorganic hybrid nanoscale materials, CuS-BSA-Cu(PO). The developed nanoparticles were characterized by various techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis absorption spectrophotometry, Fourier transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS). The CuS-BSA-Cu(PO) were successfully applied as artificial colorimetric probes in sensing HO, the final outcome of glucose oxidation, and proved to be efficient peroxidase mimics for the catalytic conversion of a chromogenic substrate, 3,3',5,5'-tetramethylbenzidine (TMB), into a blue colored oxidized product (oxTMB) which can be easily visualized by the naked eye and monitored by a great absorption peak at 654 nm in the UV-vis spectrophotometry. A highly efficient, rapid, sensitive, and selective determination of HO and glucose have been achieved with very low detection limits of 22 nM, and 27.6 nM over 0-8 μM and 0-1000 μM linear ranges, respectively. Compared to CuS-BSA, CuS-BSA-Cu(PO) exhibited improved peroxidase-like catalytic activity. Based on these observations, the performance of this approach was successfully validated in contact lens care solutions and human serum samples.