Label-free determination of glypican-3 using PtPd@H-rGO nanocomposites decorated light-addressable potentiometric sensor

Glypican-3 (GPC3) is exclusively overexpressed in most Hepatocellular carcinoma (HCC) tissue but not in normal liver tissue, making it a promising biomarker for the precise detection of HCC. In this paper, a label-free light-addressable potentiometric sensor (LAPS) decorated by platinumpalladium-hemin-reduced graphene oxide nanocomposites (PtPd@H-rGO NCs) was constructed for determination of GPC3. The GPC3 aptamer (GPC3_Apt) and PtPd@H-rGO NCs were modified on the surface of silicon-based LAPS chip to build sensitive unit of LAPS system. A readout photocurrent elicited from a modulated light source, registers the localized surface potential change. When a bias voltage is provided to the LAPS system, the GPC3-GPC3_Apt complexes formed by the specific reaction between GPC3 and GPC3_Apt at the sensing interface can cause the sensitive membrane surface potential to change, resulting in the photocurrent-voltage (I-V) curves generate a corresponding offset response. Therefore GPC3 concentration can be determined by monitoring the potential shifts (△V). Under optimal conditions, the potential shift is linearly related to the concentration of GPC3 in the range of 0.001-3.00 μg/mL with the limit of detection (LOD) of 0.0001 μg/mL. The LAPS has a good analytical performance with good specificity, reproducibility and stability, and can be used for the detection of GPC3 in actual serum samples, which provides a broad application prospect for the combined application of LAPS and aptamers in biooassay.