No abstract

The highly sensitive detection of hydrogen peroxide (H2O2) is of practical importance due to its involvement in the biofunction and signal transduction of cells. Various electrochemical techniques have been explored and studied for its detection, which can be realized through either enzymatic or non-enzymatic sensors. Particularly, non-enzymatic biosensors have been in great demand because of their high stability, high reproducibility, and less susceptible to environmental factors compared to the enzyme-based approach. However, many of them display inferior sensitivity or poor selectivity. Hence, this work aims to develop a highly sensitive non-enzymatic biosensor through structural and compositional approaches. From a structural point of view, Au inverse opals are utilized as the sensor scaffold due to their intriguing porous structure. The spatial arrangement of these materials resembles a honeycomb structure, which provides a high specific surface area, efficient mass transport, and strong mechanical stability. In addition to the benefits brought by inverse opals, we further incorporate a composite coating based on Cu2O to decorate the scaffold surface. Through the combination of a well-ordered pore structure with additional functionalization by composite formation, a synergistic improvement could be realized. To fabricate such structural biosensors, an expedited self-assembly process exploiting electrophoresis technique is first adopted to produce a colloidal crystal template. Subsequent electrodeposition processes are performed to construct the Au inverse opals and relevant functional coatings. The sensing performance of these 3D sensors is then evaluated by the detection of H2O2 using cyclic voltammetric analysis. Their structural and compositional characterizations are conducted by SEM, EDX, XPS, and Raman spectroscopy.

The detection of hydrogen peroxide (H2O2) is of practical importance due to its involvement in the functioning and signal transduction of living cells. Various electrochemical techniques have been explored using either enzymatic or non-enzymatic sensors. In particular, non-enzymatic biosensors have attracted considerable attention because of their impressive stability and reproducibility. In addition, they are less susceptible to environmental interferences. However, the primary drawback of non-enzymatic sensors is poor sensitivity and selectivity. Hence, we want to address this issue by fabricating Cu2O in an inverse opaline structure. Our process involves the preparation of Au inverse opals serving as a three-dimensional ordered macroporous conductive substrate that allows an excessive surface area and sufficient porosity for mass transport. The Cu2O is electrodeposited on the Au inverse opals for the detection of H2O2. Comprehensive electrochemical analysis and materials characterization are conducted and discussed.