Zhang Chunhong, Ren Hao, Jiang Xiangkui, Jia Guangfeng, Pan Zhigang, Liu Yongchun
Xi'an Key Laboratory of Advanced Control and Intelligent Process, School of Automation, Xi'an University of Posts & Telecommunications, Xi'an 710121, China.
Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, China.
Nanomaterials (Basel). 2022 Jun 23;12(13):2152. doi: 10.3390/nano12132152.
An aggregation or assembly of Ag triangular nanoplates (Ag TNPs) can cause dramatic changes in their optical properties, which is widely used in applications in the field of sensing. The assembly forms of nanoparticles are crucial for obtaining sensitive sensing signals, but it is unknown what kind of assembly dominates the aggregated Ag TNPs in aqueous solutions. Herein, using thiram-induced Ag TNP aggregation as a model, six different assembly models were established, including three planar (side-by-side, side-to-tip, and tip-to-tip) assemblies and three tridimensional (plane-to-plane, plane-to-tip, and plane-to-side) assemblies. The corresponding optical properties were then investigated. Both theoretical and experimental findings indicate that three-dimensional assemblies, especially plane-to-plane assembly, dominate the Ag TNPs aggregation solution, causing a blue shift of the absorption spectrum. Analysis of charge distribution patterns in Ag TNPs indicates that such a blue shift is caused by the electrostatic repulsive force in plane-to-plane assembly. Thus, we propose a simple colorimetric method for thiram detection using Ag TNPs as an indicator. The method exhibits a selective and sensitive response to thiram with a limit of detection of 0.13 μM in the range of 0.2-0.5 μM, as well as excellent performance in real samples like wheat.
银三角形纳米片（Ag TNPs）的聚集或组装会使其光学性质发生显著变化，这在传感领域的应用中被广泛使用。纳米颗粒的组装形式对于获得灵敏的传感信号至关重要，但尚不清楚在水溶液中哪种组装形式在聚集的Ag TNPs中占主导地位。在此，以福美双诱导的Ag TNP聚集为模型，建立了六种不同的组装模型，包括三种平面（并排、边对尖和尖对尖）组装和三种三维（面对面、面到尖和面到边）组装。然后研究了相应的光学性质。理论和实验结果均表明，三维组装，尤其是面对面组装，在Ag TNPs聚集溶液中占主导地位，导致吸收光谱发生蓝移。对Ag TNPs中电荷分布模式的分析表明，这种蓝移是由面对面组装中的静电排斥力引起的。因此，我们提出了一种以Ag TNPs为指示剂检测福美双的简单比色法。该方法对福美双表现出选择性和灵敏的响应，在0.2 - 0.5 μM范围内检测限为0.13 μM，并且在小麦等实际样品中具有优异的性能。
