School of Chemistry and Chemical Engineering, Yangzhou University , Yangzhou 225002, Jiangsu People's Republic of China.
Langmuir. 2017 Dec 5;33(48):13811-13820. doi: 10.1021/acs.langmuir.7b03430. Epub 2017 Nov 20.
In the present work, we use β-casein as a model protein to prepare a smart β-casein stabilized Pt nanoparticle (CM-PtNP) with peroxidase mimicking activity and systematically investigate sulfide-mediated switching effect and mechanism of CM-PtNP nanozyme's activity. Sulfide-mediated activity switching effect depends heavily on the physicochemical properties of nanozymes and the identity of substrate. On one hand, the binding of sulfide to a Pt nanozyme surface leads to the transform from Pt to Pt, resulting in more active sites and the activity "switching on"; on the other hand, the binding of sulfide ions via Pt-S interaction blocks the active sites, resulting in the activity "switching off". For substrates 3,3',5,5'-tetramethylbenzidine and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt, the two factors play different decisive roles since the interaction of substrate molecules with nanozyme allows their different distributions on nanozyme surfaces. By virtue of this specific response, excellent sulfide colorimetric sensors with different limits of detection were developed based on CM-PtNP with different substrates. This is the first report about a fundamental understanding of how substrates influence the anion-mediated activity switching effect by illuminating the nature of anion-nanozyme interaction and nanozyme-substrate interaction. This may be useful to rationally predict the environment factors on the activities of the nanozyme and to design an effective signal amplification based on target-induced nanozyme deactivation/activation.
在本工作中，我们以 β-乳球蛋白为模型蛋白，制备了具有过氧化物酶模拟活性的智能β-乳球蛋白稳定的 Pt 纳米粒子（CM-PtNP），并系统研究了硫化物介导的 CM-PtNP 纳米酶活性的开关效应及其机制。硫化物介导的活性开关效应强烈依赖于纳米酶的物理化学性质和底物的特性。一方面，硫化物与 Pt 纳米酶表面的结合导致从 Pt 到 Pt 的转变，从而产生更多的活性位点，实现“开启”活性；另一方面，通过 Pt-S 相互作用结合的硫化物离子会封锁活性位点，从而导致“关闭”活性。对于底物 3,3',5,5'-四甲基联苯胺和 2,2'-联氮双（3-乙基苯并噻唑啉-6-磺酸）二铵盐，这两个因素起着不同的决定性作用，因为底物分子与纳米酶的相互作用允许它们在纳米酶表面上的不同分布。基于具有不同底物的 CM-PtNP，我们开发了具有不同检测限的出色硫化物比色传感器，利用了这种特定的响应。这是首次报道了关于阴离子如何通过阐明阴离子-纳米酶相互作用和纳米酶-底物相互作用的本质来影响阴离子介导的活性开关效应的基本理解。这可能有助于合理预测环境因素对纳米酶活性的影响，并设计基于目标诱导的纳米酶失活/激活的有效信号放大。
