Establishment And Application Of Self-Assembled Tetrahedral Electrochemical Aptasensor Targeting Chloramphenicol

As an antibacterial broad-spectrum antibiotic,chloramphenicol(CAP)has been banned in animal-sourced food by many countries because it has brought unpredictable adverse effects on human health and social environment while inhibiting and sterilizing.However,the problem of abuse still exists,and a large of CAP residues endangering human health.Therefore,there is a pressing need to construct an efficient,convenient and rapid detection method for CAP residues in animal-sourced foods.In this study,we developed an electrochemical aptasensor based on a tetrahedral structure for the detection of CAP residues.The aptasensor detection performance depends on the specific competition of CAP with the tetrahedral structure side chains for the limited Apt-CAP.Realized the quantitative detection of CAP concentration in real milk samples.The main research contents including:1.The synthesis process of DNA tetrahedral structure was characterized by electrophoresis,and the structure stability and CAP binding-related conformational changes of the tetrahedral structure and traditional doublestranded structure were compared.The results showed that the former has better placement stability and higher conformational changes related to CAP binding,and the tetrahedral structure is more suitable for the construction of aptasensors than the traditional double-stranded structure.2.Constructed an electrochemical aptasensor targeting CAP based on DNA tetrahedral structure.Based on the detection principle,the Apt-CAP loading capacity of the two sensors was compared,and the detection conditions were optimized.The Apt-CAP concentration loaded by the tetrahedral structure was 7.47 μM,which was approximately 3.5 times of the double-stranded structure.The optimal detection conditions for the fabricated aptasensor were as follows: tetrahedral-aptamer complex concentration of 2μM,12 h incubation time to immobilize tetrahedron-aptamer complex on the electrode,and the final detection duration time of 30 min.3.The aptasensor exhibited a high sensitivity and selectivity to detected CAP with the optimized conditions,the limit of detection(LOD)is 0.0676ng/mL,linear range from 0.19 ng/mL to 387.76 ng/mL.Moreover,the recoveries of CAP in the spiked milk samples were 100.57%—101.69%,and the single detection costs 9.78 (?).These results indicated that the constructed aptasensor can be applied to the detection of CAP in animal-derived food.