Precipitation of aqueous transition metals in particulate matter during the dithiothreitol (DTT) oxidative potential assay
Precipitation of aqueous transition metals in particulate matter during the dithiothreitol (DTT) oxidative potential assay
复制标题
二硫苏糖醇 (DTT) 氧化电位测定过程中颗粒物中水性过渡金属的沉淀
DOI：
10.1039/d2em00005a
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Reed, Brian E.
中科院分区：
文献类型：
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作者：
Yalamanchili, Jayashree;Hennigan, Christopher J.;Reed, Brian E.
根据颗粒物质（PM）中过渡金属的氧化电位（OP），假设它们具有增强的毒性。脱细胞二硫苏糖醇（DTT）法被广泛用于测定PM及其化学成分的OP。在我们之前的研究中，我们发现DTT法（pH 7.4, 0.1 M磷酸盐缓冲液，37°C）为PM中存在的多种金属的沉淀提供了有利的热力学条件。本研究利用多种技术表征水金属的沉淀存在于低浓度的DTT分析。利用激光粒子光散射分析、直接化学测量和显微成像技术确定了金属析出。实验用来自不同金属盐的水金属和具有良好特征的城市PM标准（NIST SRM-1648a，城市颗粒物）进行。我们的结果表明，在DTT分析快速沉淀金属。金属析出与DTT无关，但与金属浓度有关。在化学复杂的城市PM样品中，金属的去除超过了热力学预测和单金属盐实验中看到的去除，表明可能发生了共沉淀和/或吸附。这些结果对使用磷酸盐缓冲液研究PM金属的其他脱细胞分析以及随后从这些分析中推断的PM毒性具有广泛的意义。
Transition metals in particulate matter (PM) are hypothesized to have enhanced toxicity based on their oxidative potential (OP). The acellular dithiothreitol (DTT) assay is widely used to measure the OP of PM and its chemical components. In our prior study, we showed that the DTT assay (pH 7.4, 0.1 M phosphate buffer, 37 °C) provides favorable thermodynamic conditions for precipitation of multiple metals present in PM. This study utilizes multiple techniques to characterize the precipitation of aqueous metals present at low concentrations in the DTT assay. Metal precipitation was identified using laser particle light scattering analysis, direct chemical measurement of aqueous metal removal, and microscopic imaging. Experiments were run with aqueous metals from individual metal salts and a well-characterized urban PM standard (NIST SRM-1648a, Urban Particulate Matter). Our results demonstrated rapid precipitation of metals in the DTT assay. Metal precipitation was independent of DTT but dependent on metal concentration. Metal removal in the chemically complex urban PM samples exceeded the thermodynamic predictions and removal seen in single metal salt experiments, suggesting co-precipitation and/or adsorption may have occurred. These results have broad implications for other acellular assays that study PM metals using phosphate buffer, and subsequently, the PM toxicity inferred from these assays.