Shanghai Key Laboratory for Urban Ecological Process and Eco-Restoration, School of Ecological and Environmental Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.
Institute of Eco-Chongming, 3663 Zhongshan Road, Shanghai 200062, China.
ACS Appl Mater Interfaces. 2020 Sep 16;12(37):42119-42128. doi: 10.1021/acsami.0c11834. Epub 2020 Aug 31.
In this study, by rationally designing the stimulus response of graphene quantum dot (GQD)-sensitized terbium/guanine monophosphate (Tb/GMP) infinite coordination polymer (ICP) nanoparticles, we have constructed a smartphone-based colorimetric assay with ratiometric fluorescence, which could be applied for the detection of acetylcholinesterase (AChE) and organophosphorus pesticides (OPs) directly. First, GQDs with abundant functional groups were chosen as the guest, which not only could be used as one of the signal readouts but also served as the antenna ligand to further sensitize the fluorescence of the host Tb/GMP. Upon being excited at 330 nm, the green fluorescence of the Tb/GMP host is highly enhanced, while the blue fluorescence of GQDs is suppressed due to the confinement of the ICP host. With the presence of thiocholine (TCh), an enzymatic product hydrolyzed from acetylthiocholine (ATCh) by AChE, the competitive coordination of Tb between GMP and TCh results in the collapse of the ICP network and thereby the release of GQDs into the solution; thus, the fluorescence of Tb/GMP turns off and the fluorescence of GQDs turns on. The dual-responsive ratiometric fluorescent intensity change leads to the corresponding green-to-blue fluorescent color change obviously, which constitutes a novel mechanism for the colorimetric analysis of AChE. Moreover, when OPs are subsequently introduced, the activity of AChE is blocked, thus preventing the stimulus response of GQD@Tb/GMP ICP nanoparticles, leading to the fluorescent color change from greenish-blue to green, which could also be employed for OP detection. Benefitting from the high sensitivity, good reliability, and the obvious color changes, the method demonstrated here is a promising candidate to realize smartphone-based point-of-use applications, which is of great importance for timely clinical diagnosis and treatment of OPs related to health issues with AChE as an exposure biomarker in less industrialized countries, in remote settings, or even in home care services.
在这项研究中，通过合理设计石墨烯量子点（GQD）敏化铽/鸟嘌呤单磷酸（Tb/GMP）无限配位聚合物（ICP）纳米粒子的刺激响应，我们构建了一种基于智能手机的比率荧光比色分析方法，可直接用于乙酰胆碱酯酶（AChE）和有机磷农药（OPs）的检测。首先，选择具有丰富官能团的 GQD 作为客体，它不仅可以用作信号读出之一，还可以作为天线配体进一步敏化主体 Tb/GMP 的荧光。在 330nm 激发下，Tb/GMP 主体的绿色荧光得到高度增强，而由于 ICP 主体的限制，GQD 的蓝色荧光受到抑制。当存在硫代胆碱（TCh）时，TCh 是 AChE 从乙酰硫代胆碱（ATCh）水解产生的酶产物，Tb 与 GMP 之间的竞争性配位导致 ICP 网络崩溃，从而将 GQD 释放到溶液中；因此，Tb/GMP 的荧光关闭，而 GQD 的荧光打开。双响应比率荧光强度变化导致相应的绿-蓝荧光颜色变化明显，这构成了 AChE 比色分析的新机制。此外，当随后引入 OPs 时，AChE 的活性被阻断，从而阻止 GQD@Tb/GMP ICP 纳米粒子的刺激响应，导致荧光颜色从蓝绿色变为绿色，这也可用于 OPs 检测。受益于高灵敏度、良好的可靠性和明显的颜色变化，这里展示的方法是实现基于智能手机的现场应用的有前途的候选方法，这对于在欠发达国家、偏远地区甚至家庭护理服务中，以 AChE 作为暴露生物标志物，及时进行与 OPs 相关的健康问题的临床诊断和治疗非常重要。
