A fluorescence turn-on biosensor based on gold nanoclusters and aptamer for alpha fetoprotein detection

Abstract

Alpha-fetoprotein (AFP), an important tumor marker, is widely used for the diagnosis of patients with germ cell tumors and hepatocellular carcinoma. Herein, a highly sensitive aptasensor for AFP detection was constructed based on fluorescence resonance energy transfer (FRET) between 5-carboxyfluorescein (FAM) and gold nanoclusters (AuNCs). AuNCs can effectively quench the fluorescence of FAM-AFP aptamer via strong coordination interactions. When AFP was introduced into the FAM-AFP aptamer-AuNCs FRET system, the AFP aptamer preferentially combined with AFP accompanied by conformational change, which greatly weakened the coordination interaction between the AFP aptamer and AuNCs. Thus, fluorescence recovery of FAM was observed. In the range of 10.0 -100.0 ng/mL, a linear relationship between the fluorescence recovery rate and the concentration of AFP was obtained with the detection limit of 6.631ng/mL. The highly sensitive FRET aptasensor with simple configuration showed promising prospect in detecting a variety of biomarkes.