Direct Detection of <i>S</i>-Nitrosothiols Using Planar Amperometric Nitric Oxide Sensor Modified with Polymeric Films Containing Catalytic Copper Species
作者:Wansik Cha、Youngmi Lee、Bong Kyun Oh、Mark E. Meyerhoff
DOI:10.1021/ac048192u
日期:2005.6.1
The direct amperometric detection of S-nitrosothiol species (RSNOs) is realized by modifying a previously reported amperometric nitric oxide gas sensor with thin hydrophilic polyurethane films containing catalytic Cu(II)/(I) sites. Catalytic Cu(II)/(I)-mediated decomposition of S-nitrosothiols generates NO(g) in the thin polymeric film at the distal tip of the NO sensor. Three different species are examined to create the catalytic layer: (1) a lipophilic Cu(II)−ligand complex; (2) Cu(II)−phosphate salt; and (3) small (3-μm) metallic Cu0 particles. All three catalytic layers yield reversible amperometric response in proportion to the concentration of S-nitrosothiols (e.g., nitrosocysteine, nitrosoglutathione, S-nitroso-N-acetylcysteine, S-nitrosoalbumin) present in the aqueous test solution. Sensitivity toward the different RSNO species is dependent on the respective catalytic rates of decomposition of the RSNO species by reactive Cu(I), accessibility of the species into the polyurethane layer containing the catalyst, the level of reducing agents (ascorbate) used in solution to help generate reactive Cu(I) species, and the concentration of metal ion complexing agents present in the test solution (e.g., EDTA). Under optimized conditions, all RSNO species can be detected at ≤1 μM levels, with sensor lifetimes of at least 10 days for the sensors based on Cu(II)−phosphate and Cu0 particles. It is further shown that the new RSNO sensors can be used to assess the “NO-generating” ability of fresh blood samples by effectively detecting the total level of reactive RSNO species present in such samples.
通过对之前报道过的安培法一氧化氮气体传感器进行改良,使其具有含催化 Cu(II)/(I) 位点的亲水聚氨酯薄膜,从而实现了对 S-亚硝硫醇物种(RSNOs)的直接安培检测。催化 Cu(II)/(I)介导的 S-亚硝硫醇分解会在氮氧化物传感器远端聚合物薄膜中生成 NO(g)。我们研究了生成催化层的三种不同物质:(1) 亲脂性 Cu(II)-ligand 复合物;(2) Cu(II)-phosphate 盐;(3) 金属 Cu0 小颗粒(3-μm)。所有三个催化层都能产生可逆的安培反应,与水性测试溶液中的 S-亚硝硫醇(如亚硝基半胱氨酸、亚硝基谷胱甘肽、S-亚硝基-N-乙酰半胱氨酸、S-亚硝基白蛋白)浓度成比例。对不同 RSNO 物种的敏感性取决于活性 Cu(I)对 RSNO 物种各自的催化分解率、RSNO 物种进入含有催化剂的聚氨酯层的可及性、溶液中用于帮助生成活性 Cu(I) 物种的还原剂(抗坏血酸盐)的含量以及测试溶液中存在的金属离子络合剂(如 EDTA)的浓度。在优化条件下,所有 RSNO 物种的检测浓度均≤1 μM,基于磷酸铜(II)和 Cu0 粒子的传感器寿命至少为 10 天。研究进一步表明,新的 RSNO 传感器可用于评估新鲜血液样本的 "NO 生成 "能力,有效检测这些样本中存在的活性 RSNO 物种的总水平。