Photoelectrochemical Immunoassay of Alpha-Fetoprotein Based on Au Nanoparticles-Decorated ZnO Microrods

Abstract

Herein a split-type photoelectrochemical (PEC) immunosensor based on in situ grown gold nanoparticles (Au NPs) on the surface of ZnO microrods (ZnO MRs) was devised for the detection of alpha-fetoprotein (AFP) by employing dopamine (DA)-loaded liposomes as the signal amplification strategy. Specifically, as the level of AFP rises, a proportional number of sandwich-type immunocomplexes form in the well of the microplate, which can introduce a corresponding amount of DA-encapsulated liposomes at the same time. Encapsulated DA molecules will be released with the stimulation of Triton X-100, thereby resulting in the marked enhancement of the PEC signal. Under optimized conditions, the proposed PEC immunosensing platform displays specific photocurrent responses toward AFP in a broad dynamic working range of 0.05 −50 ng mL⁻¹, achieving an impressively low limit of detection (LOD) of 18.7 pg mL⁻¹. Furthermore, this methodology not only displays high specificity, and satisfactory storage stability but also ensures acceptable accuracy and practicality for the analytical applications of human serum samples.