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 (Fe 3 O 4 /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 Fe 3 O 4 /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 Fe 3 O 4 /GO nanosheets. The Fe 3 O 4 /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·mL −1 ) and the detection limit is 3.01 ng·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. Graphical abstract A sensitive homogeneous FRET-based apatasensor was designed for GPC3 detection where the AuCDs-GPC3 Apt is a donor and Fe 3 O 4 /GO nanosheets are an acceptor. The GPC3 fluorescent aptasensor combines wider output range with low cost, high specificity, and good anti-interference.