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

Abstract

Copper, an essential element to play significant roles in human health, can bind β-amyloid peptide (Aβ) to form Cu2+-Aβ 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 Cu2+ and Aβ based on V2O5 nanofibers (NFs)/CdS nanoparticles (NPs) as the photoactive material. Specially, V2O5 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 V2O5 NFs by electrochemical deposition method. The well-matched energy level between V2O5 NFs and CdS NPs effectively suppresses the recombination of photogenerated electron and hole (e-/h+) pairs, leading to the admirable photocurrent response. Cu2+ 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 Aβ based on the high affinity of Cu2+ for Aβ. In the presence of Aβ, its recognition with Cu2+ led to the generation of Cu2+-Aβ complexes onto the V2O5/CdS surface, resulting in the recovery of PEC response. Under optimal conditions, the proposed PEC sensor possessed the detection limits toward Cu2+ and Aβ as low as 0.15 nM and 8.0 fM, respectively. The “off–on” PEC probe was successfully applied to the detection of Cu2+ and Aβ in the practical samples. The simple and sensitive PEC probe of V2O5 NFs/CdS NPs shows great potential applications in biological analysis and early disease diagnosis.