Yang Wenrong, Chow Edith, Willett Gary D, Hibbert D Brynn, Gooding J Justin
School of Chemical Sciences, The University of New South Wales, Sydney 2052, Australia.
Analyst. 2003 Jun;128(6):712-8. doi: 10.1039/b212881k.
The modification of electrodes with the tripeptide Gly-Gly-His for the detection of copper in water samples is described in detail. The tripeptide modified electrode was prepared by first self-assembling 3-mercaptopropionic acid (MPA) onto the gold electrode followed by covalent attachment of the tripeptide to the self-assembled monolayer using carbodiimide coupling. The electrodes were characterized using electrochemistry, a newly developed mass-spectrometry method and quantum mechanical calculations. The mass spectrometry confirmed the modification to proceed as expected with peptide bonds formed between the carboxylic acids of the MPA and the terminal amine of the peptide. Electrochemical measurements indicated that approximately half the MPA molecules in a SAM are modified with the peptide. The peptide modified electrodes exhibited high sensitivity to copper which is attributed to the stable 4N coordinate complex the peptide formed around the metal ion to give copper the preferred tetragonal coordination. The formation of a 4 coordinate complex was predicted using quantum mechanical calculation and confirmed using mass spectrometry. The adsorption of the copper to the peptide modified electrode was consistent with a Langmuir isotherm with a binding constant of (8.1 +/- 0.4) 10(10) M(-1) at 25 degrees C.
详细描述了用三肽甘氨酰 - 甘氨酰 - 组氨酸修饰电极用于检测水样中的铜。三肽修饰电极的制备方法是先将3 - 巯基丙酸（MPA）自组装到金电极上，然后使用碳二亚胺偶联将三肽共价连接到自组装单分子层上。使用电化学、一种新开发的质谱方法和量子力学计算对电极进行了表征。质谱证实修饰按预期进行，MPA的羧酸与肽的末端胺之间形成了肽键。电化学测量表明，自组装单分子层中约一半的MPA分子被肽修饰。肽修饰电极对铜表现出高灵敏度，这归因于肽在金属离子周围形成的稳定的四配位络合物，使铜具有优选的四方配位。使用量子力学计算预测了四配位络合物的形成，并通过质谱得到证实。铜在肽修饰电极上的吸附符合朗缪尔等温线，在25℃下结合常数为(8.1±0.4)×10¹⁰ M⁻¹。
