Huang Weiwen, Wang Yichen, Wang Lumei, Pan Chaoqiang, Shen Guoqing
School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China.
Anal Methods. 2021 Jan 7;13(1):90-98. doi: 10.1039/d0ay01811b. Epub 2020 Dec 10.
A colorimetric method is described for detection of the antibiotic ciprofloxacin (CIP) in aqueous solutions based on an unmodified CIP-aptamer and gold nanoparticles (AuNPs), which are regarded as a probe and an indicator, respectively. In the absence of CIP, aptamers can hybridize with poly dimethyl diallyl ammonium chloride (PDDA) to form a 'duplex' structure through electrostatic interactions, and AuNPs remain dispersed in solution, leading to a red solution and an obvious absorption peak at 520 nm. Contrarily, the CIP-aptamer can specifically bind to CIP after the introduction of CIP into the solution. Then PDDA is thus free to aggregate AuNPs. The solution turns blue from red accordingly, presenting a strong absorption at 650 nm. Hence, the concentration of CIP can be quantified through the changes of the absorption. This sensitive and selective colorimetric method for CIP detection has a good linear response (R = 0.9935) in the 20 to 300 nM CIP concentration range, with a limit of detection (LOD) of 0.215 nM. Importantly, the proposed aptasensor demonstrates great application potential in CIP determination in aqueous samples.
本文描述了一种基于未修饰的环丙沙星适配体和金纳米颗粒（AuNPs）的比色法，用于检测水溶液中的抗生素环丙沙星（CIP），其中金纳米颗粒和未修饰的环丙沙星适配体分别被视为探针和指示剂。在不存在环丙沙星的情况下，适配体可以通过静电相互作用与聚二甲基二烯丙基氯化铵（PDDA）杂交形成“双链体”结构，金纳米颗粒仍分散在溶液中，溶液呈红色，在520nm处有明显的吸收峰。相反，将环丙沙星引入溶液后，环丙沙星适配体可以特异性地与环丙沙星结合。然后，PDDA从而能够使金纳米颗粒聚集。溶液相应地从红色变为蓝色，在650nm处有强烈吸收。因此，可以通过吸收变化来定量环丙沙星的浓度。这种用于检测环丙沙星的灵敏且选择性比色法在20至300 nM的环丙沙星浓度范围内具有良好的线性响应（R = 0.9935），检测限（LOD）为0.215 nM。重要的是，所提出的适配体传感器在水性样品中环丙沙星的测定中显示出巨大的应用潜力。
