氧化苏木精复合电极测定牛奶中残留青霉素

Determination of Trace Penicillin in Milk By Self-made Hematein Modified Electrode

用戊二醛-牛血清白蛋白交联法将青霉素酶、纳米金胶和氧化苏木精同时修饰在铂电极上,制成电流型电化学生物传感器. 实验结果表明,当电位一定时,青霉素浓度的微小变化与氧化苏木精还原反应的计时电流值成正比,据此可测定牛奶中残留的青霉素. 传感器响应时间为4 s,在磷酸缓冲溶液和牛奶中,线性范围分别为2.81×10^-5～1.26×10^-2 mmol/L和5.61×10^-4～2.10×10^-3 mmol/L,电极使用寿命为15 d. 15 d内重现性较好,电极保存寿命为30 d. 同时应用电化学阻抗技术对传感器反应机理进行了探讨.

Penicillinase, hematein and nano gold colloid were immobilized, as a modified membrane, on a plane Pt electrode by glutaraldehyde-bovine serum albumin. The membrane-modified electrode was used to construct amperometric electrochemical biosensors for the determination of trace penicillin in milk. The principle is based on the use of pH-sensitive hematein as the redox-active probe molecule. At a suitable constant potential, when the local pH on the electrode surface or in its promixity changes as a consequence of the penicillin hydrolyzation, the current flow resulting from the electrochemical reaction of hematein also changes to an extent, which is correlated to the substrate concentration. To characterize the interactions of enzyme with nano Au colloid and hematein, electrochemical impedance spectroscopy （EIS） was used. The linear detection range of the modified Pt electrode is from 2. 81 ×10^-5 to 1.26×10^-2 mmol/L in PBS and from 5.61 ×10^-4 to 2. l0 ×10^-3mmol/L in milk. The response time is 4 s. The electrode can be used for at least 15 days with the perfect reproducibility, The life of the electrode is 30 days.