Photoelectrochemical nanoprobe for combined monitoring of Cu2+ and β-amyloid peptide

Copper, an essential element to play significant roles in human health, can bind β -amyloid peptide (A β ) to form Cu 2+ -A β complexes and spontaneously generate harmful reduced oxygen species leading to oxidative stress in the brain. Herein, we present a simple, novel off–on photoelectrochemical (PEC) sensor for dual detection of Cu 2+ and A β based on V 2 O 5 nanofibers (NFs)/CdS nanoparticles (NPs) as the photoactive material. Specially, V 2 O 5 NFs were prepared by the recrystallization method and then modified onto indium tin oxide (ITO) electrode. CdS NPs were subsequently deposited onto the surface of V 2 O 5 NFs by electrochemical deposition method. The well-matched energy level between V 2 O 5 NFs and CdS NPs effectively suppresses the recombination of photogenerated electron and hole (e - /h + ) pairs, leading to the admirable photocurrent response. Cu 2+ specifically coordinated with CdS to produce a CuxS adduct, which quenched the PEC intensity due to the recombination of excited electrons and holes. Interestingly, the constructed PEC sensing platform also exhibited a sensitive response to A β based on the high affinity of Cu 2+ for A β . In the presence of A β , its recognition with Cu 2+ led to the generation of Cu 2+ -A β complexes onto the V 2 O 5 /CdS surface, resulting in the recovery of PEC response. Under optimal conditions, the proposed PEC sensor possessed the detection limits toward Cu 2+ and A β as low as 0.15 nM and 8.0 fM, respectively. The “off–on” PEC probe was successfully applied to the detection of Cu 2+ and A β in the practical samples. The simple and sensitive PEC probe of V 2 O 5 NFs/CdS NPs shows great potential applications in biological analysis and early disease diagnosis.