核酸适配体氯化血红素比色法检测牛奶中的氯霉素

利用一种基于适配体氯化血红素(hemin)比色分析法快速检测牛奶中的氯霉素(chloram-phenicol,CAP)含量.设计两条DNA链,其中一条为CAP的核酸适配体,在其3′端修饰氯化血红素;另一条为CAP核酸适配体的互补链(cDNA),在其5′端修饰hemin.当体系中无CAP时,两条DNA单链杂交形成DNA双...

Colorimetric Method for the Detection of Chloramphenicol in Milk Based on Aptamer and Hemin

A colorimetric method for rapid detection of chloramphenicol(CAP) in milk was developed based on hemin-modified aptamer.Two DNA strands,the aptamer of CAP and its complementary strand(cDNA),were introduced.The hemin molecules were modified at the 3-end of the aptamer and the 5′ end of the cDNA,respectively.In the absence of CAP,two DNA single strands hybridized to form a double strand.Two hemin monomers formed dimers which reduced their peroxidase activities and was thus unable to catalyze the oxidization of 3,3′,5,5′-tetramethylbenzidine(TMB) by H2O2 to produce a blue colored product.In the presence of CAP,the CAP specifically hybridized with the aptamer.The DNA double strands were dissociated and the peroxidase activity of hemin monomers was restored which effectively catalyzed the oxidization of TMB by H2O2 to present blue colored product.The absorbance at 452 nm was recorded after adding of the stop solution.Under the optimal conditions,the colorimetric method showed a good linear response for CAP detection in the range of 1 30 nmol/L.The detection limit based on the 3σ/k criterion reached 0.315 nmol/L.The recovery tested by the spiked CAP in milk samples was 95.5%-116.0%,showing that the method can be used to sensitively and accurately detect CAP in milk.