Marzouk S A, Ufer S, Buck R P, Johnson T A, Dunlap L A, Cascio W E
Department of Chemistry, University of North Carolina, Chapel Hill 27599-3290, USA.
Anal Chem. 1998 Dec 1;70(23):5054-61. doi: 10.1021/ac980608e.
In the present paper, fabrication, characterization, and physiological applications of a solid-state pH electrode are described. The pH sensing layer was based on an anodic electrodeposited iridium oxide film (AEIROF). Sputtered platinum electrodes (1 mm diameter) fabricated on flexible Kapton films or platinum wires were used as planar or cylindrical supports. Each electrode site was coated with Nafion to attenuate the interference of anionic redox species and to protect the electrode surface during in vivo measurements. Performance of the AEIROF was evaluated, for the first time, as a pH electrode and proved to have a slightly super-Nernstian response with slope of -63.5 +/- 2.2 mV/pH unit for both wire and planar sputtered platinum electrodes. Linear pH responses were obtained in the pH range 2-10. The electrodes have a working lifetime of at least 1 month with accuracy of about 0.02 pH unit and fast response time. The electrodes showed very low sensitivities for different species, such as Na+, K+, Li+, NH4+, Ca2+, Mg2+, dissolved oxygen, lactate, ascorbate, and urate, which are important for physiological applications. The electrodes were applied in extracellular pH measurements during brief regional ischemia in a swine heart and no-flow ischemia in an isolated rabbit papillary muscle. A first report on extracellular pH, K+, and lactate simultaneous measurements during no-flow ischemia using the AEIROF pH electrode and the previously described K+ and lactate electrodes is presented as well.
本文描述了一种固态pH电极的制备、表征及其生理应用。pH传感层基于阳极电沉积氧化铱薄膜（AEIROF）。在柔性聚酰亚胺薄膜或铂丝上制备的溅射铂电极（直径1 mm）用作平面或圆柱形支撑体。每个电极部位都涂有Nafion，以减弱阴离子氧化还原物质的干扰，并在体内测量过程中保护电极表面。首次将AEIROF作为pH电极进行性能评估，结果表明，对于丝状和平面溅射铂电极，其斜率为-63.5±2.2 mV/pH单位，具有略超能斯特响应。在pH范围2-10内获得了线性pH响应。这些电极的工作寿命至少为1个月，精度约为0.02 pH单位，响应时间快。对于Na+、K+、Li+、NH4+、Ca2+、Mg2+、溶解氧、乳酸、抗坏血酸和尿酸等对生理应用很重要的不同物质，该电极显示出非常低的灵敏度。这些电极被应用于猪心脏短暂局部缺血和离体兔乳头肌无血流缺血期间的细胞外pH测量。还首次报道了使用AEIROF pH电极以及先前描述的K+和乳酸电极在无血流缺血期间同时测量细胞外pH、K+和乳酸的情况。
