甲氨蝶呤的电化学测定及与溶菌酶相互作用的研究

Electrochemical determination of methotrexate and its interaction with lysozyme

研究甲氨蝶呤（MTX）在石墨烯修饰玻碳电极上的电化学行为，探讨MTX与溶菌酶（LYSO）的相互作用及其作用机理。结果发现，在pH4．5的HAc—NaAc缓冲溶液中，石墨烯修饰电极对MTX的电化学氧化具有明显的催化作用，氧化峰电流相对于在裸玻碳电极上增加了5倍。线性范围为0．05～3．0μmol／L，检出限（S/N=3）为0．02μmol／L。对0．8μmol／L的MTX11次平行测定，RSD为3．5％。当LYSO加入MTX溶液后，其峰电流降低。紫外光谱有红移增色效应。MTX与LYsO结合比为l：1，结合常数为4．9×10 5L／mol。方法可用于MTX片药物的检测及与蛋白相互作用的研究。

A novel electrochemical method was modified glassy carbon electrode （GP/GCE） developed for the determination of methotrexate at a graphene The interaction between methotrexate and Lysozyme was investigated by linear sweep voltammetry, UV-Vis spectrometry and IR spectroscopy, the mechanism of the interaction with Lysozyme was discussed. The results showed that in HAc-NaAc （pH 4.5 ） buffer, the GP/GCE exhibited excellent catalytic and enhancement effect on the electrochemical oxidation of methotrexate, and the oxidation peak current increased ca. 5 times compared with that at a bare GCE. A good linear relationship between the peak current and methotrexate concentration from 0. 05 to 3.0 μmol/L was obtained, and the detection limit （ S/N = 3 ） was 0. 02 μmol/L. The relative standard derivation was 3.5 for 0. 8 μmol/L methotrexate. In the presence of various concentrations of lysozyme, the redox peak current of MTX was decreased, which indicated that methotrexate could react with lysozyme and form an electrochemical inactive compound. The hyperchromic effect with red shift on the absorption spectrum proved that MTX could react with lysozyme. The binding ratio was calculated as 1 ： 1 and the binding equilibrium constant was 4.9 × 10 6 L/mol. The operation was simple, rapid, sensitive and accurate, and could be used in the detection of methotrexate pills and its interaction with protein.