基于聚二硫二丙烷磺酸膜修饰FET延长栅极的L-胱氨酸传感器

L-Cystine Sensor Based on Modification of Extended Gate of FET with Polydithiodipropanesulfonic Acid Membrane

将场效应晶体管(FET)的栅极金电极(GGE)延长一定距离,在GGE表面自组装上聚二硫二丙烷磺酸(SPS)膜,构建了一种可检测L-胱氨酸(L-cystine)的新型传感装置.该传感界面的SEM表征、电化学性能测试和XPS分析结果表明,在溶液中带负电荷的SPS聚阴离子膜可通过静电作用吸附结合带正电荷的目标物L-胱氨酸,形成双电层结构而产生识别一价有机铵离子的膜电位.该电极在磷酸盐缓冲溶液(pH=5. 0)中对L-胱氨酸有良好的电位响应性能,线性范围为5. 0×10^(-6)～1. 0×10-3mol/L,响应灵敏度为(58. 25±1. 5)m V/-pc(25℃),检出限为2. 69×10^(-6)mol/L.该电极响应快(30 s),重现性及稳定性好.常见氨基酸如L-甘氨酸、L-丙氨酸、L-缬氨酸、L-天冬氨酸、L-脯氨酸、L-苏氨酸、L-组氨酸、L-亮氨酸、L-色氨酸及L-甲硫氨酸等均不干扰电极对L-胱氨酸的测定.该电极可用于实际猪血清样品中L-胱氨酸的测定,回收率为91. 2%～107. 8%,说明该方法是一种装置简便,能准确测定L-胱氨酸的新手段.

A novel sensing device capable of detecting L-cystine was constructed by designing the gate gold electrode(GGE)of a field effect transistor(FET)to extend a certain distance and self-assembly of polydithiodipropanesulfonic acid(SPS)on the surface of GGE.The topological structure of the modified GGE was characterized by means of scanning electron microscopy.Through electrochemical cyclic voltammetry and impedance analysis together with X-ray photoelectron spectroscopy,the response mechanism of the SPS modified GGE for the L-cystine detection has been well investigated.With electrostatic interaction,the SPS poly-anion membrane with negative charge in aqueous solution could adsorb the L-cystine molecules containing positive charge,which may form a double electric layer resulting in change of membrane potential on the sensing interface by recognition of monovalent organic ammonium ion.The electrode exhibited a nice linear potential performance to L-cystine in the range of 5.0×10-6~1.0×10-3 mol/L,with a slope of(58.25±1.5)mV/-p c(25℃)and a detection limit of 2.69×10-6 mol/L.The response time for L-cystine was very fast(30 s).The electrode also had good reproducibility and stability.Almost no interferences from common amino acids such as L-glycine,L-alanine,L-valine,L-aspartate,L-proline,L-threonine,L-histidine,L-leucine,L-tryptophan or L-methionine can be observed.Moreover,the electrode can be applied to the determination of L-cystine in real pig serum samples with recovery rate of 91.2%-107.8%.It shows that the sensing device is expected to become a kind of simple and accurate means for the L-cystine analysis.