A magnetic separation-based dual-mode aptasensor integrating FRET fluorescence and UV absorption for early diagnosis of hepatocellular carcinoma.

Early diagnosis of hepatocellular carcinoma (HCC) is crucial for improving patient survival; however, conventional detection methods using HepG2 cells (a typical HCC cell line) have inherent limitations. To address this issue, we constructed a magnetic separation-based dual-mode aptasensor that integrates FRET fluorescence (using FAM-labeled aptamers and BHQ-modified P2 strands) with AgNPs-based UV absorption. This design enables dual-signal self-validation from the precipitate (fluorescence) and the supernatant (UV). Key experimental conditions were systematically optimized. Under optimal conditions, the aptasensor exhibited good linear responses to HepG2 cells in the range of 0-5 × 105 cells per mL. For the FRET fluorescence mode, the calibration curve was FL = 249.5C + 317.1 (R2 = 0.989), while for the UV mode, it was A = 0.0504C + 0.1154 (R2 = 0.981). The aptasensor also demonstrated excellent specificity. Furthermore, it effectively detected HepG2 cells in human serum, with regression equations of FL = 285C + 620 (R2 = 0.991) for the fluorescence mode and A = 0.0296C + 0.1405 (R2 = 0.978) for the UV mode. This dual-mode aptasensor provides a novel and reliable method for the early diagnosis of HCC, leveraging the complementary advantages of FRET fluorescence and UV absorption.