建立了一种高灵敏度阻抗电化学免疫分析法测定青霉素的方法。利用层层自组装技术将多壁碳纳米管（MWCNTs），壳聚糖（CS），和HRP标记青霉素抗体（HRP-Ab*）共固定于玻碳电极表面，利用HRP可以催化H2O2的还原进一步促进对苯二酚的氧化，从而引起阻抗的变化，然后根据电流的变化从而实现了对牛奶中青霉素的定量测量。对于牛奶样品，需要盐析以除去其蛋白质和脂肪，同时对缓冲液的pH、免疫温度和时间都进行了优化。实验表明，在优化条件下，该传感器的响应电流与青霉素的浓度在0.05~5 μg L-1范围内有较好的线性关系，相关系数为0.9853，检测限是1.05 μg/L。最后，通过和酶联免疫法（ELISA）对比，可知该法测定青霉素灵敏度高,重复性好,特异性高,可适合用于检测牛奶样品中的青霉素残留。

An amperometric immunosensor with enhanced sensitivity was successfully developed by co-immobilization of multi-walled carbon nanotubes (MWCNTs), Chitosan (CS), and HRP labled penicillin polyclonal antibody (HRP-Ab*) on glassy carbon electrode using a layer-by-layer assembly technique. HRP can catalyze the reduction of H2O2 to promote the oxidation of hydroquinone, causing the changes in impedance, thus realizing the quantitative detection of penicillin according to the current changes. The milk samples were pretreated by salting out to remove the protein and fat. And the effects of pH of buffer solution，immune temperature and time were investigated. Under optimized conditions, the current response of the sensor showed a good linear relationship with the concentration of penicillin in 0.05~5.00 μg/L, with the correlation coefficient of 0.9853 and the detection limit of 1.05 μg/L. This method was fast, simple and reliable, with high sensitivity, specificity compared to enzyme-linked immunosorbent assay (ELISA). It was proved to be suitable for detection of penicillin residues in milk samples .

国家科技支撑计划（2012BAK08B01）；宁波市创新团队（2012B82017）；宁波市人事局人才基金（ZX2012000380）