Highly Sensitive Detection For Cocaine Using Molybdenum Disulfide-DNA Based Sensors

Cocaine is a stimulant that can be harm to human physical and psychological health.It can cause a series of mental illnesses and even death for the drug abuser.The development of the highly sensitive detection is of great significance for treatment and prognosis of drugster.Molybdenum disulfide is functionalized by gold nanoparticles,and the molybdenum disulfide-gold nanoparticle complex has more excellent physical and chemical properties.The aptamer is a single stranded DNA or RNA that can bind to the target specially.This study constructs a molecular biology tool,the biosensor,based on molybdenum disulfide（MoS₂）-gold nanoparticles（AuNPs）nucleic acid compounds with aptamer of cocaine to develop a few new methods and technology for detecting cocaine with high sensitivity.（1）Detection of cocaine based on molybdenum-gold nanoparticles（AuNPs）using colorimetric method.The absorption spectrum of gold nanoparticles is closely related to its dispersion state.The complex of the aptamer and cocaine could enhance the dispersion of gold nanoparticles,and molybdenum disulfide can be used as a temporary repository for aptamer.Analyzing the cocaine is through measuring the values at 520 nm and 680 nm and the detection limit for cocaine is 7.49n M.（2）The detection of cocaine based on the surface of molybdenum disulfide-gold nanoparticles with aptamer.Tween 80 can promote combination between MoS₂@AuNPs and aptamer and eliminate efficiently nonspecific adsorption with the detection limit being 2 pM.On the basis of single-thiol aptamer,partially complementary aptamer with double thiol is used to strengthen the immobilization on surface of MoS₂@AuNPs and improve the sensitivity of detection.The detection limit is improved,which is 1.56 pM,compared to the results of the single-thiol aptamer.Furthermore,the free-label aptamer is linked to the surface of MoS₂@AuNPs which can realize the detection with low signal background and the detection limit is 0.54 pM.（3）The detection of cocaine based on molybdenum disulfide-gold nanoparticle with polyadenylic acid（Poly A）in the terminal.Poly adenosine can combine gold nanoparticles with strong ability.The surface of MoS₂@AuNPs binds aptamer modified by fluorescence with Poly A to detect cocaine,and its limit of detection is3.44 pM.（4）The detection of cocaine based on the molybdenum disulfide-gold nanoparticle chip.A sensor system for cocaine detection is constructed by Cy5-aptamer and the MoS₂@AuNPs which is fixed on amino-containing glass slide.The sensor is highly sensitive for cocaine and it can implement multi-sample analysis.Furthermore,it can detect cocaine as low as 0.304 nM.This can be developed into a chip with high-throughput detection.Developing several new techniques and methods are used to detect cocaine with high sensitivity using the above research and provide the support for human health.