A highly sensitive strategy for glypican-3 detection based on aptamer/gold carbon dots/magnetic graphene oxide nanosheets as fluorescent biosensor

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths in China. Glypican-3 (GPC3) is a specific antigen related to HCC, which is widely used in clinical detection as a reliable marker of HCC. In this paper, a highly sensitive homogeneous apatasensor was designed for GPC3 detection based on fluorescence resonance energy transfer (FRET) where the GPC3 aptamer labelled gold carbon dots (AuCDs-GPC3(Apt)) are used as a donor and magnetic graphene oxide (Fe3O4/GO) nanosheets are used as an acceptor. A one-step hydrothermal method was used to synthesize AuCDs to provide sufficient fluorescence. The FRET phenomenon exists between AuCDs-GPC3(Apt) and Fe3O4/GO, which weakens the fluorescence intensity of the whole system. When the target GPC3 is added to the FRET system, the fluorescent AuCDs-GPC3(Apt) binds to the GPC3 and forms a folded structure, which leads to AuCDs-GPC3(Apt) separation from Fe3O4/GO nanosheets. The Fe3O4/GO is then magnetically separated so that the fluorescence of free labelled AuCDs-GPC3(Apt) is restored. Under the optimum conditions, the fluorescence recovery rate is linearly correlated with the concentration of GPC3 (5-100 ng center dot mL(-1)) and the detection limit is 3.01 ng center dot mL(-1) (S/N = 3). This strategy shows recoveries from 98.76 to 101.29% in real human serum samples and provides an immediate and effective detection method for the quantification of GPC3 with great potential applications for early diagnosis of HCC.

Automated summary

In this study, a highly sensitive apatasensor for detecting GPC3 was designed based on FRET. The GPC3 aptamer labelled gold carbon dots were used as a donor and magnetic graphene oxide nanosheets were used as an acceptor. The detection method showed a linear correlation between the fluorescence recovery rate and the concentration of GPC3, with a low detection limit. Real human serum samples demonstrated good recovery rates, indicating the potential application of this method for early diagnosis of HCC.