Green approach for in-situ growth of highly-ordered 3D flower-like CuS hollow nanospheres decorated on nitrogen and sulfur co-doped graphene bionanocomposite with enhanced peroxidase-like catalytic activity performance for colorimetric biosensing of glucose.

We describe a green and facile hydrothermal route to synthesize highly ordered 3D flower-like hierarchical CuS hollow nanospheres@N-S-rGO bionanocomposite used to detect glucose. After synthesis and comprehensive characterization of all potential catalysts, the peroxidase-like activity of 3D CuS NSs@N-S-rGO is compared extensively with pure 3D CuS NSs, N-S-rGO, N-rGO, and GO to monitor the effect of each modification and treatment on their catalytic properties. The results indicate promising peroxidase activity of 3D CuS NSs@N-S-rGO by possessing the highest catalytic activity and the Michaelis constant of ~93.5 times lower and 9.7 times higher than that of reported for HRP, respectively. The bionanocomposite is used to detect glucose in serum with and without light. The results show a remarkable enhancement in the limit of detection for glucose from 0.3 μM to 0.075 μM (40 folds) with visible light that can be attributed to the fast electron transfer on the surface of 3D CuS NSs@N-S-rGO and the synergistic interaction of 3D CuS NSs and N-S-rGO. The method was further applied to the colorimetric detection of glucose in human serum and showed high selectivity. Our result also show that this method based on 3D CuS NSs@N-S-rGO is economical, reliable, feasible, and highly efficient.