建立了一种简单、可靠的基于载入树状分子内部的纳米金修饰电极用于亚硝酸根测定的电化学分析方法.将壳聚糖(Chit)修饰在玻碳电极表面,在偶联活化剂碳二亚胺存在的条件下,4.5代羧基末端的树状分子(Dendrimer)通过其外围的羧基与壳聚糖的氨基形成酰胺键而连接在电极表面.Au(Ⅲ)通过与树状分子内部氮的配位作用被结合在树状分子内部,再将其还原形成纳米金(AuNPs),构成Den (AuNPs)/Chit/GCE.采用循环伏安法、交流阻抗法研究了修饰电极的电化学行为.结果表明,Den (AuNPs)/Chit/GCE能显著提高电化学测定亚硝酸根的灵敏度,且计时电流响应快速、稳定,亚硝酸根浓度在2～20 μnol/L及0.07～ 1.12mmol/L范围内与其电化学氧化电流呈良好线性,检出限(S/N=3)可达1.0 μmol/L.将该方法用于实际样品的分析,结果满意.Den (AuNPs)/Chit/GCE为电化学传感器和生物传感器的进一步研究提供了平台.%A simple and reliable method was developed for the electrochemical determination of nitrite based on glassy carbon electrode (GCE) modified with Au nanoparticles(AuNPs) encapsulated in den-drimers. Firstly, chitosan(Chit) was modified on the GCE, and in the presence of coupling agent carbodiimide, carboxyl-terminated poly ( amidoamine ) ( generation 4. 5 ) dendrimers were covalently attached onto chitosan through the formation of amide bonds between carboxylic acid groups of the dendrimer and amine groups of chitosan. The Au ( Ⅲ) ions were coordinated in the interior of den-drimer with nitrogen ligands and then reduced to form AuNPs, which was written as Den ( AuNPs) / Chit/GC electrode. The Den( AuNPs)/Chit/GC electrodes were characterized with cyclic voltamme-try(CV) , electrochemical impedance spectroscopy(EIS). The experimental results showed that the present Den ( AuNPs) /Chit/GC electrodes have excellent sensitivity for nitrite determination. The chronoamperometric studies revealed that the amperometric response was rapid and stable, and offered a linear dependence over the ranges of nitrite concentrations from 2 μmol/L to 20 μmol/L and 0.07 mmol/L to 1. 12 mmol/L with a limit of detection( S/N = 3) down to 1.0 μmol/L. The method was applied in the determination of nitrite in real sample with satisfactory result. Den (AuNPs)/Chit/ GC electrodes are to provide a nanostructured platform for the development of electrochemical sensors and biosensors.
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