Hunan Provincial Key Laboratory of Micro Materials Interface Science, College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, P. R. China.
Department of Geriatrics, The Third Xiangya Hospital of Central South University, Changsha, Hunan 510060, P. R. China.
ACS Sens. 2020 Sep 25;5(9):2959-2965. doi: 10.1021/acssensors.0c01511. Epub 2020 Sep 16.
Apolipoprotein E (apoE) polymorphic genes are one of the main genetic determinants of Alzheimer's disease (AD) risk. Relying on the toehold-mediated strand displacement reaction (SDR), the dual-signal electrochemical assay of apoE genotyping with potential applications in the early diagnosis of AD has been achieved. The displacement of the surface-confined methylene blue- and ferrocene-capped detection probe-modified gold nanoparticles (AuNPs) by the complementary sequences (Tc 1 and Tc 2, fragment of allele ε4 at codon 112 and that of allele ε3 or ε4 at codon 158, respectively), triggered by the highly specific SDR, results in decreased voltammetric signals. In contrast, partial strand displacement caused by the single mismatched sequences (Tsm 1 and Tsm 2, fragment of allele ε2 or ε3 at codon 112 and that of allele ε2 at codon 158, respectively) produces larger voltammetric signals. The proposed method serves as a versatile platform for the discrimination of six apoE genotypes, including three homozygotes (ε2/2, ε3/3, and ε4/4) and three heterozygotes (ε2/3, ε2/4, and ε3/4), and for the quantification of apoE ε3/3 from genomic DNA extracts of AD patients.
载脂蛋白 E (apoE) 多态性基因是阿尔茨海默病 (AD) 风险的主要遗传决定因素之一。基于适体介导的链置换反应 (SDR)，实现了载脂蛋白 E 基因分型的双信号电化学分析，具有 AD 早期诊断的应用潜力。由于高度特异性的 SDR，由互补序列 (Tc1 和 Tc2，分别为等位基因 ε4 在密码子 112 处和等位基因 ε3 或 ε4 在密码子 158 处的片段) 引发的表面受限的亚甲基蓝和二茂铁封端的检测探针修饰的金纳米粒子 (AuNP) 的置换，导致伏安信号降低。相比之下，由于单错配序列 (Tsm1 和 Tsm2，分别为等位基因 ε2 或 ε3 在密码子 112 处和等位基因 ε2 在密码子 158 处的片段) 引起的部分链置换会产生更大的伏安信号。所提出的方法可作为区分六种载脂蛋白 E 基因型的通用平台，包括三种纯合子 (ε2/2、ε3/3 和 ε4/4) 和三种杂合子 (ε2/3、ε2/4 和 ε3/4)，并用于从 AD 患者的基因组 DNA 提取物中定量载脂蛋白 E ε3/3。
