Department of Chemistry and R.N. Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, Kansas 66045, United States.
Department of Analytical Chemistry, UNESCO Laboratory of Environmental Electrochemistry, Charles University, Prague 212843, Czech Republic.
Anal Chem. 2022 Feb 15;94(6):2942-2949. doi: 10.1021/acs.analchem.1c04879. Epub 2022 Feb 2.
Oxytocin is a nonapeptide hormone involved in numerous physiological functions. Real-time electrochemical measurements of oxytocin in living tissue are challenging due to electrode fouling and the large potentials needed to oxidize the tyrosine residue. Here, we used fast-scan cyclic voltammetry at carbon-fiber microelectrodes and flow injection analysis to optimize a waveform for the measurement of oxytocin. This optimized waveform employed an accumulation potential of -0.6 V, multiple scan rates, and a 3 ms holding potential at a positive, oxidizing potential of +1.4 V before linearly scanning the potential back to -0.6 V (versus Ag/AgCl). We obtained a limit of quantitation of 0.34 ± 0.02 μM, and our electrodes did not foul upon multiple injections. Moreover, to demonstrate the utility of our method, we measured the release of oxytocin, evoked by light application and mechanical perturbation, in whole brains from genetically engineered adult zebrafish that express channelrhodopsin-2 selectively on oxytocinergic neurons. Collectively, this work expands the toolkit for the measurement of peptides in living tissue preparations.
催产素是一种涉及多种生理功能的九肽激素。由于电极污垢和氧化酪氨酸残基所需的大电势，实时电化学测量活组织中的催产素具有挑战性。在这里，我们使用碳纤维微电极的快速扫描循环伏安法和流动注射分析来优化用于测量催产素的波形。该优化波形采用-0.6 V 的累积电位、多个扫描速率和 3 ms 的保持电位，在正、氧化电位+1.4 V 下保持 3 ms，然后在线性扫描回-0.6 V（相对于 Ag/AgCl）。我们得到的定量下限为 0.34±0.02 μM，并且我们的电极在多次注射后不会被污染。此外，为了证明我们的方法的实用性，我们测量了在表达通道视紫红质-2的成年斑马鱼的全脑中，通过光应用和机械扰动诱发的催产素释放。总的来说，这项工作扩展了在活组织制剂中测量肽的工具包。
