Highly sensitive detection for cocaine using an aptamer–cocaine–aptamer method

Abstract

In this study, a thiol-modified aptamer was immobilized on a gold nanoparticle-modified molybdenum disulfide composite material (MoS₂@AuNPs), which could remove the interference of physical adsorption and reduce false positive signals. Furthermore, a non-fluorescent dual-thiol aptamer was immobilized on the surface of MoS₂@AuNPs with a low background signal. After attaching the cocaine using a dual-thiol aptamer immobilized on the surface of MoS₂@AuNPs, cocaine could be detected using a cocaine aptamer with 5-carboxyfluorescein (FAM). The aptamer–cocaine–aptamer complex was used to form a fluorescence signal, which made the signal noise (S/N) relatively high and sensitive to cocaine detection with 0.54 pM. Under optimal conditions, the change in the fluorescence intensity of the sensor was proportional to the concentration of cocaine in the range of 0–0.1 nM. This experiment was carried out in a human serum sample, and results showed that the analysis of cocaine using this sensor was promising.