Label-free detection of glypican-3 using reduced graphene oxide /polyetherimide/gold nanoparticles enhanced aptamer specific sensing interface on light-addressable potentiometric sensor

Glypican-3 (GPC3) protein is considered as an effective and specific biomarker for the accurate diagnosis of hepatocellular carcinoma (HCC), and there is a critical demand to construct strategies with shorter time, lower cost noise and higher sensitivity. In this study, a biosensor for label-free detection of GPC3 was prepared by modifying GPC3 aptamer (GPC3Apt) on the surface of Si-based light addressable potentiometric sensor (LAPS) chip modified by reduced graphene oxide/polyetherimide/gold nanoparticles (rGO/PEI/AuNPs). Among them, GPC3Apt with a low equilibrium dissociation constant was used as a biorecognition molecule to recognize and capture GPC3. The rGO/PEI/AuNPs decorated on the LAPS surface could enlarge the surface area for GPC3Apt immobilization and provide more active sites for GPC3Apt to bind effectively with the target GPC3. When a bias voltage was provided to the LAPS system, the forming GPC3-GPC3Apt complexs on the sensing interface of LAPS would cause the potential of the sensitive membrane surface to change and generate a corresponding offset response in photocurrent-voltage (I-V) curves. The potential shift and GPC3 concentration showed a good linear range from 0.1 to 100.0 μg/mL with a detection limit of 40.0 ng/mL (S/N = 3) and a sensitivity of 1.33638 mV/μg/mL. In addition, the LAPS detection system also has good specificity and stability, which can be used for the detection of GPC3 in spiked serum samples.