Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box U1987, Perth, WA 6845, Australia.
Chem Asian J. 2013 Sep;8(9):2096-101. doi: 10.1002/asia.201300215. Epub 2013 Jun 7.
The behavior of proteins and polypeptides at electrified aqueous-organic interfaces is of benefit in label-free detection strategies. In this work, rat amylin (or islet amyloid polypeptide) was studied at the interface formed between aqueous liquid and gelled organic phases. Amylin is a polypeptide that is co-secreted with insulin from islet beta-cells and is implicated in fibril formation. In this study, rat amylin was used, which does not undergo aggregation. The polypeptide underwent an interfacial transfer process, from water to the gelled organic phase, under applied potential stimulation. Cyclic voltammetry revealed steady-state forward and peak-shaped reverse voltammograms, which were consistent with diffusion-controlled water-to-organic transfer and thin-film stripping or desorptive back-transfer. The diffusion-controlled forward current was greater when amylin was present in an acidic aqueous phase than when it was present in an aqueous phase at physiological pH; this reflects the greater charge on the polypeptide under acidic conditions. The amylin transfer current was concentration dependent over the range 2-10 μM, at both acidic and physiological pH. At physiological pH, amylin was selectively detected in the presence of a protein mixture, which illustrated the bioanalytical possibilities for this electrochemical behavior.
在非标记检测策略中，蛋白质和多肽在带电水-有机界面的行为是有益的。在这项工作中，研究了在由水相和凝胶有机相形成的界面处的大鼠胰岛淀粉样多肽（或胰岛淀粉样多肽）。胰岛淀粉样多肽是一种与胰岛素一起从胰岛β细胞分泌的多肽，与纤维形成有关。在这项研究中，使用了不会发生聚集的大鼠胰岛淀粉样多肽。在施加电势刺激下，多肽从水相向凝胶有机相经历界面转移过程。循环伏安法揭示了稳态正向和峰形反向伏安图，这与扩散控制的水-有机转移和薄膜剥离或解吸反向转移一致。当胰岛淀粉样多肽存在于酸性水相时，扩散控制的正向电流大于当它存在于生理 pH 的水相时；这反映了在酸性条件下多肽带更多的电荷。在酸性和生理 pH 条件下，在 2-10 μM 的范围内，胰岛淀粉样多肽的转移电流与浓度有关。在生理 pH 下，在蛋白质混合物存在的情况下可以选择性地检测到胰岛淀粉样多肽，这说明了这种电化学行为的生物分析可能性。
