A homogeneous biosensor for carbohydrate antigen 153 detection in human serum based on upconversion fluorescence resonance energy transfer

Quantitative determination of carbohydrate antigen 153 (CA153) in human serum plays an important role in early diagnosis of breast cancer. In this work, a highly sensitive and selective biosensor for CA153 detection was developed based on a fluorescent resonance energy transfer (FRET) strategy, in which near-infrared (NIR)-excitable upconversion nanoparticles (UCNPs) and the commercial organic dye, FAM, were employed as energy donor and energy acceptor, respectively. The two components were linked by a molecular beacon (MB) containing CA153 aptamer sequence and the upconversion fluorescence (UCF) of UCNPs can be effectively quenched by FAM. In presence of CA153, the hairpin structure was opened, resulting in the separation of UCNPs and FAM and the inhibition of FRET. The UCF showed a linear relationship with the logarithm of CA153 concentration in the range from 0.01 to 150 U/mL, with a LOD of 4.5 mU/mL in HEPES buffer. This probe can be successfully applied for CA153 assay in human serum, which may be a useful tool for early diagnosis of breast cancer.