Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, College of Chemistry & Chemical Engineering, Northwest Normal University, Lanzhou 730070, China.
College of Chemistry and Chemical Engineering, Lanzhou City University, Lanzhou, 730070, China.
Anal Chim Acta. 2020 Aug 15;1125:114-127. doi: 10.1016/j.aca.2020.05.047. Epub 2020 May 23.
Advanced oxidation processes (AOPs) have recently proposed for advancing colorimetric sensing applications, owing to their excellent performance of sensitive color readout that generated from the oxidation of chromogenic substrates like 3,3',5,5'-tetramethylbenzidine (TMB) by reactive oxygen species (ROS) of AOPs such as ·OH and ·O radicals. However, the efficiency of ROS generation and the related HO decomposition in most AOPs is quite low especially at neutral pH, which greatly hampered the practical sensing applications of the AOPs. We herein communicated that β-cyclodextrin (β-CD)-capped gold nanoparticles (β-CD@AuNPs) can promote catalysis at neutral pH for AOP as an excellent co-catalyst. In this strategy, inorganic pyrophosphate (PPi) ions was first used to coordinate with Cu and form Cu-PPi complex. In the presence of hydrogen peroxide, target inorganic pyrophosphatase (PPase) can hydrolyze PPi into inorganic phosphate (Pi) and release free Cu simultaneously, resulting in a Cu-triggered Fenton-like AOP reaction. The introduced β-CD@AuNPs acts as a co-catalyst, analogous to mediators in the most co-catalyzed system, to enhance the rate-limiting step of Cu/Cu conversion in Cu/HO Fenton-like AOP and resulting in an efficient generation of ·OH and ·O radicals, which further producing an intense blue color by oxidizing TMB into its oxidation product (TMBox) within a short time. Finally, this reaction system was used to simply detecting target PPase with the colorimetric and photothermal readout based on the in-situ generated TMBox indicator. More significantly, we successfully demonstrated nanozyme can serve as a co-catalyst to promote the AOP catalysis at neutral pH, and inspire other strategies to overcome the pH limitation in the AOP catalysis and expand its colorimetric and photothermometric application.
高级氧化工艺（AOPs）最近因其出色的氧化显色性能而被提出，用于推进比色传感应用，这些显色底物如 3,3',5,5'-四甲基联苯胺（TMB）被 AOPs 产生的活性氧物种（ROS）如·OH 和·O 自由基氧化后会产生敏感的颜色读数。然而，大多数 AOPs 中 ROS 的生成效率及其相关的 HO 分解效率相当低，特别是在中性 pH 下，这极大地阻碍了 AOPs 的实际传感应用。我们在此传达，β-环糊精（β-CD）封端的金纳米颗粒（β-CD@AuNPs）可以作为一种出色的共催化剂，在中性 pH 下促进 AOP 的催化作用。在这种策略中，首先使用无机焦磷酸根（PPi）离子与 Cu 配位形成 Cu-PPi 配合物。在过氧化氢存在的情况下，目标无机焦磷酸酶（PPase）可以将 PPi 水解为无机磷酸盐（Pi）并同时释放游离的 Cu，导致 Cu 触发的类芬顿 AOP 反应。引入的β-CD@AuNPs 作为共催化剂，类似于大多数共催化体系中的介体，增强了 Cu/HO 类芬顿 AOP 中 Cu/Cu 转化的限速步骤，并导致·OH 和·O 自由基的有效生成，这些自由基通过在短时间内将 TMB 氧化成其氧化产物（TMBox）进一步产生强烈的蓝色。最后，该反应系统用于通过基于原位生成的 TMBox 指示剂的比色和光热读出来简单地检测目标 PPase。更重要的是，我们成功地证明了纳米酶可以作为共催化剂来促进中性 pH 下的 AOP 催化，并激发了其他策略来克服 AOP 催化中的 pH 限制，扩大其比色和光热应用。
