Department of Chemistry and Materials Science, Jiangsu Key Laboratory of Green Synthesis for Functional Materials , Jiangsu Normal University , Xuzhou , Jiangsu 221116 , P. R. China.
Department of Chemistry, Waterloo Institute for Nanotechnology , University of Waterloo , Waterloo , Ontario N2L 3G1 , Canada.
Langmuir. 2019 Jun 4;35(22):7304-7311. doi: 10.1021/acs.langmuir.9b01161. Epub 2019 May 22.
Gold nanoparticles (AuNPs) have been extensively used for detecting arsenite, As(III). Many methods rely on a DNA aptamer that claimed to bind specifically to inorganic arsenic. In these cases, the focus was on arsenic binding to the aptamer, while the potential interactions between As(III) and the AuNP surface were ignored. Herein, a set of spectroscopic and isothermal titration calorimetry (ITC) experiments were conducted to measure the adsorption of As(III) by AuNPs and its competition with DNA adsorption. With 10 mM As(III), 18% of adsorbed DNA was displaced from AuNPs, while preadsorption of only 20 μM As(III) inhibited DNA adsorption by around 50%. The affinity of As(III) on AuNPs is comparable to Br and guanosine. ITC and Raman spectroscopy both indicated that only As(III) can be adsorbed, while As(V) had no measurable interactions with the AuNPs. Based on this understanding, a random DNA sequence was used and a similar colorimetric response in the presence of As(III) was observed. This study confirmed the affinity between As(III) and the gold surface. The As(III)/gold interaction is strong enough to affect DNA adsorption, and care should be taken to interpret the observations based on the color change of AuNPs for the detection of As(III).
金纳米粒子（AuNPs）已被广泛用于检测亚砷酸盐，As（III）。许多方法都依赖于一种据称能特异性结合无机砷的 DNA 适体。在这些情况下，重点是砷与适体的结合，而忽略了 As（III）与 AuNP 表面之间的潜在相互作用。在此，进行了一组光谱和等温滴定量热法（ITC）实验，以测量 As（III）被 AuNPs 吸附及其与 DNA 吸附的竞争。当存在 10 mM As（III）时，有 18%的吸附 DNA 从 AuNPs 上被取代，而仅预吸附 20 μM 的 As（III）就可抑制约 50%的 DNA 吸附。As（III）在 AuNPs 上的亲和力可与 Br 和鸟嘌呤核苷相媲美。ITC 和拉曼光谱都表明只有 As（III）可以被吸附，而 As（V）与 AuNPs 没有可测量的相互作用。基于这一认识，使用了随机 DNA 序列，并在存在 As（III）的情况下观察到了类似的比色响应。本研究证实了 As（III）与金表面之间的亲和力。As（III）/金的相互作用足够强，会影响 DNA 的吸附，因此在基于 AuNPs 颜色变化检测 As（III）时，应注意根据其变化来解释观察结果。
