Highly Sensitive Detection for Cocaine Using Aptamer-Cocaine-Aptamer Method
In this study, the thiol-modified aptamer is immobilized on the gold nanoparticle-modified molybdenum disulfide composite material (MoS2@AuNPs), which can remove the interference of physical adsorption and reduce the false positive signal. Furthermore, non-fluorescent dual-thiol aptamer was immobilized on the surface of MoS2@AuNPs with low background signal. After attaching the cocaine using dual-thiol aptamer immobilized on the surface of MoS2@AuNPs, cocaine could be detected using a cocaine aptamer with FAM. The aptamer-cocaine-aptamer complex was used to form a fluorescent 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 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 human serum and results showed that the analysis of cocaine using this sensor was promising.