对苯二胺在血红蛋白/聚L-谷氨酸/玻碳修饰电极上的可逆氧化

采用电聚合法在玻碳电极(GCE)表面得到导电性能良好的聚L-谷氨酸(PGA)薄膜，通过共价键合法将血红蛋白(Hb)固定于电极表面得到稳定且具有催化活性的Hb/PGA/GCE修饰电极，将其用于对苯二胺(PPD)的可逆氧化。 修饰电极交流阻抗及血红蛋白直接电化学实验表明，血红蛋白成功地固定于电极表面，保持良好的电催化活性，能有效催化H₂O₂的还原。 PPD在电极上表现为受吸附控制的准可逆氧化还原反应，I_p,a/I_p,c约为1.02，电极没有明显的钝化现象。 氧化还原峰电流与PPD的浓度均呈良好的线性关系，I_p,a(μA)=3.124+0.705c_PPD(mmol/L)(r=0.9973)。 H₂O₂的存在使PPD氧化还原峰型更对称，可逆性更好，表明体系中PPD氧化与过氧化酶催化途径一致。

Reversible Oxidation of p-Phenylenediamine on Hemoglobin/poly(L-glutamic acid)/Glassy Carbon Modified Electrode

A hemoglobin/poly(L-glutamic acid)/glassy carbon electrode(Hb/PGA/GCE), targeted for reversible oxidation of p-phenylenediamine(PPD), has been fabricated by covalently immobilizing Hb on GCE with a thin layer of conductive pre electropolymerized PGA. Electrochemical impedance spectra of the electrode confirmed the immobilization of Hb. The resulting modified electrode(Hb/PGA/GCE) gave a redox couple for Hb in PBS buffer and a better electrocatalytic performance to H₂O₂. This indicated that the direct electron transfer of the active group of the protein could be retained on the electrode surface. The oxidation of PPD was reversible on Hb/PGA/GCE instead of GCE or PGA/GCE. The redox peak current was proportional to the scan rate, and I_p,a/I_p,c about 1.02, indicating a characteristic of quasi-reversible, surface confined electrochemical behavior. Moreover, a new measurement method for PPD in samples was provided since the redox peak currents increased linearly with the concentration of PPD, I_p,a(μA)=3.124+0.705c_PPD(mmol/L)(r=0.9973). The enzymatic oxidation might be the plausible mechanism because the existence of H₂O₂ was in favor of the reversible redox of PPD.