Michalska Agnieszka, Golczak Sebastian, Langer Krzysztof, Langer Jerzy J
Laboratory for Materials Physicochemistry and Nanotechnology, Faculty of Chemistry, Umultowska 89b; Wielkopolska Centre for Advanced Technologies (WCZT), Umultowska 89c, Adam Mickiewicz University in Poznań, Poznań, Poland.
Nanomaterials (Basel). 2019 Feb 8;9(2):231. doi: 10.3390/nano9020231.
The unique properties of nanomaterials enable the creation new analytical devices. Polyaniline (PANI) micro- and nanofiber network, freestanding in the gap between two gold microelectrodes, has been used in a new nanodetector for metal ions in solutions. The gold electrodes were modified with the aid of alkanethiols, forming a self-assembled monolayer (SAM), which is able to block the ion current flow, but also to interact with metal ions when specific functional molecules are incorporated into the layer. The electric field of the trapped metal ions induces change of the electrical conductivity of polyaniline nanofibers in vicinity. A small injected sample (75 μL) of a solution of salt (about 0.5 μg of salt) was enough to induce a reproducible change in the electrical conductivity of polyaniline nano-network, which was registered as a function of time within 10⁻20 s. The response was proportional to the concentration of ions. It also depends on properties of ions, e.g., the ionic radius, which allows for identification of metal ions by analyzing the parameters of the signal: the retention time (RT), half width (HW), amplitude (A) and integral intensity (INT). The advantage of the new device is the instant responsiveness and easy operation, but also the simple construction based on organic (polymer) technology. The system is "open"-when learned and calibrated adequately, other metal ions can be analyzed. The nanodetector can be used in cases where monitoring of the presence and concentration of metal ions is important.
纳米材料的独特性能使得新型分析设备的制造成为可能。独立于两个金微电极之间间隙的聚苯胺（PANI）微纳纤维网络已被用于一种新型的溶液中金属离子纳米探测器。金电极借助链烷硫醇进行修饰，形成自组装单分子层（SAM），该单分子层既能阻断离子电流，又能在特定功能分子掺入该层时与金属离子相互作用。捕获的金属离子的电场会引起附近聚苯胺纳米纤维电导率的变化。一小份注入的盐溶液样品（75 μL，约含0.5 μg盐）足以引起聚苯胺纳米网络电导率的可重复变化，该变化在10⁻²⁰ s内作为时间的函数被记录下来。响应与离子浓度成正比。它还取决于离子的性质，例如离子半径，这使得通过分析信号参数：保留时间（RT）、半高宽（HW）、幅度（A）和积分强度（INT）来识别金属离子成为可能。这种新设备的优点是响应迅速、操作简便，而且基于有机（聚合物）技术的结构简单。该系统是“开放式”的——经过充分学习和校准后，可以分析其他金属离子。这种纳米探测器可用于监测金属离子的存在和浓度很重要的情况。
