Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan, ROC.
Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan, ROC; Center for Emergent Functional Matter Science, National Chiao Tung University, Hsinchu, Taiwan, ROC.
Anal Chim Acta. 2018 Dec 26;1042:86-92. doi: 10.1016/j.aca.2018.08.030. Epub 2018 Aug 18.
In this paper we describe a label-free biosensor for coralyne, prepared by combining DNA-stabilized silver nanoclusters (Ag NCs) with an exonuclease III amplification strategy. An artificial DNA probe having a polyadenine (poly-A) sequence at both the 3'- and 5'-ends was used as a probe to detect coralyne. In the absence of coralyne, the probe existed in a hairpin conformation that left both its 3'- and 5'-ends free. In the presence of coralyne, two adjacent adenine (A) bases in the poly-A sequence of the probe formed an A unit and then coordinated with coralyne through non-Watson-Crick base pairing. The DNA probe, having captured coralyne, was subsequently digested by exonuclease III, even though the distance between the A units in the A-coralyne-A complex would be much larger than that found in common Watson-Crick base pairing. After digestion, the DNA probe became a single-stranded DNA (ssDNA) residue and released its captured coralyne. The liberated coralyne was then coordinated by another DNA probe having the hairpin conformation; as a result, many ssDNA residues formed after digestion. Two kinds of Ag NCs having different optical utilities were obtained: one corresponding to the hairpin conformational DNA probe and the other to the ssDNA residue. The difference in fluorescence intensity at 588 nm of these two kinds of Ag NCs reflected the concentration of coralyne. The linear range (on a logarithmic scale) for detecting coralyne spanned from 5 to 1000 nM, with an estimated detection limit of 1.83 nM.
在本文中，我们描述了一种用于珊瑚素的无标记生物传感器，该传感器通过将 DNA 稳定的银纳米簇（Ag NCs）与外切酶 III 扩增策略结合而制备。使用具有聚腺苷酸（poly-A）序列的人工 DNA 探针作为探针来检测珊瑚素。在不存在珊瑚素的情况下，探针以发夹构象存在，使其 3'和 5'末端均游离。在存在珊瑚素的情况下，探针的 poly-A 序列中的两个相邻腺嘌呤（A）碱基形成一个 A 单元，然后通过非 Watson-Crick 碱基配对与珊瑚素配位。捕获了珊瑚素的 DNA 探针随后被外切酶 III 消化，尽管 A 单元在 A-珊瑚素-A 复合物中的距离会比在常见的 Watson-Crick 碱基对中发现的距离大得多。消化后，DNA 探针变成单链 DNA（ssDNA）残基并释放其捕获的珊瑚素。然后，另一个具有发夹构象的 DNA 探针与释放的珊瑚素配位；结果，消化后形成了许多 ssDNA 残基。获得了两种具有不同光学用途的 Ag NCs：一种对应于发夹构象的 DNA 探针，另一种对应于 ssDNA 残基。这两种 Ag NCs 在 588nm 处的荧光强度差异反映了珊瑚素的浓度。检测珊瑚素的线性范围（对数刻度）为 5 至 1000nM，估计检测限为 1.83nM。
