功能化纳米金增强的DNA电化学检测和序列分析

Functional Gold Nanoparticle-enhanced Electrochemical Determination of DNA Hybridization and Sequence-specific Analysis

用冠以大量二茂铁的纳米金微粒 /抗生蛋白链菌素结合物为标记物 ,将其标记于生物素修饰的寡聚核苷酸片段上 ,制成了具有电化学活性和纳米金放大作用的DNA电化学生物传感器 .首先采用巯基DNA和巯基烷烃混合自组装膜制备了金修饰电极 ,将探针DNA分子固定在了电极表面 ,运用杂交原则结合靶点分子在电极表面形成了双螺旋的DNA链 ,然后借助抗生蛋白链菌素和生物素之间的强亲和作用 ,引入了功能化的纳米金 .通过伏安法测定了修饰在纳米金上的二茂铁的氧化还原电流 ,可以识别和测定溶液中互补的靶点DNA ,17 mer靶点DNA的浓度在 0 .0 0 1～ 10nmol/L范围内有线性关系 ,检测限可达 0 .75× 10 -12 mol/L .

An electrochemical determination method for the analyzing sequence-specific DNA using ferrocene-capped gold nanoparticles/streptavidin conjugates has been developed in this work. Thiolated DNA probes were covalently immobilized on a gold electrode with hexanethiol (HT) forming mixed self-assembled monolayer and hybridized with target DNA, containing a complementary sequence. Duplex (Double-stranded) DNA was formed on the gold surface. Then functional gold nanoparticles were introduced via strong interaction effect between biotin and streptavidin. Binding events were monitored by electrochemical signal of ferrocene covering on the gold nanoparticles by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The signal differences permitted to distinguish the match of two perfectly complementary DNA strands from the near-perfect match where just one base pair was wrong. The sensitivity of this electrochemical DNA biosensor has been detected and an excellent linearity of 0.001～10 nmol/L for 17-mer target concentration with the oxidation peak current and the limit of detection of 0.75×10^(-12) mol/L were also achieved.