Horseradish Peroxidase Immobilized in Metal Aerogels Boosts Electron Transfer and an Interfacial Reaction for Photoelectrochemical Immunoassay

Photoelectrochemical (PEC) enzymatic biosensors have attracted widespread attention for their specificity and sensitivity, but the charge migration between an enzyme and a semiconductor remains uncertain. In this work, horseradish peroxidase (HRP) was successfully immobilized on ionic liquid-functioned Cu@Cu₂O (IL-Cu@Cu₂O) aerogels to boost charge transfer and an interfacial redox reaction. The photogenerated electrons flow from the conduction band of Cu₂O to HRP under the assistance of Cu and are subsequently captured by [Fe(CN)₆]^3- in the electrolyte, which boosts the PEC response. The improved interfacial catalytic ability after the immobilization of HRP is proved by the enhanced redox ability under light irradiation. Benefiting from the excellent PEC activity and catalysis reaction of IL-Cu@Cu₂O@HRP, an immunoassay platform was constructed for sensing prostate-specific antigens, which presents a wide detection range and a low limit of detection. An in-depth understanding of the direct electronic communication between a photoactive material and an enzyme for boosted charge transfer and interfacial catalysis provides a new view for the design of advanced PEC sensing platforms.