High-performance assaying phosphatidylinositol proteoglycan 3 based on a dual-mode biosensor coupling near-infrared photoelectrochemical with ratiometric electrochemical sensing

A dual-model biosensor was prepared for assaying phosphatidylinositol proteoglycan 3 (GPC3) by coupling near-infrared photoelectrochemical with ratiometric electrochemical sensing techniques. Nd-MOFs synthesized with ionic liquid and Nd3+ ions were integrated with gold nanoparticles (AuNPs) to form Nd-MOF@AuNPs nano-composites. Nd-MOF@AuNPs nanocomposites were used as a near-infrared photoactive element to construct a photoelectrochemical interface. Fc-Apt was fixed on the Nd-MOF@AuNPs based NIR photoelectrochemical interface by Au-S bond to provide electrochemical signal through the oxidation of Fc. The specific recognition of GPC3 can lead to the decrease of the photocurrent and the oxidation peak current of Fc (IFc). Subsequently, the methylene blue-labeled aptamer (MB-Apt@AuNRs) was introduced into the interface to form a sandwich immunocomplex, MB-Apt@AuNRs/GPC3/FC-Apt, resulting in the amplification of the photocurrent and the oxidation peak current of MB (IMB) and a decrease on the value of IFc. Under optimized experimental conditions, the linear response ranges for the ratiometric electrochemical (IMB/IFc) and photoelectrochemical sensing stra-tegies were 0.005-10 and 0.001-10 ng mL-1, respectively. The calculated detection limits were 0.66 and 1.9 pg/ mL. The dual-model biosensing system provides good performances in determining GPC3 in human serum samples, and can be considered as a potential tool for the diagnosis of tumor.