聚多巴胺包埋G-四联体/血红素DNA酶制备过氧化氢生物传感器

An Electrochemical Hydrogen Peroxide Biosensor Based on Polydopamine-Entrapped G-Quadruplex-Hemin DNAzyme

利用多巴胺的氧化自聚实现对G-四联体/血红素DNA酶的包埋,成功构建了H2O2电化学生物传感器。DNA和血红素混合得到G-四联体/血红素复合物;DNA酶物理吸附在玻碳电极上后,将10μL 5 g/L多巴胺的磷酸盐缓冲液(pH 8.0)滴在表面,空气中的氧气氧化多巴胺形成聚多巴胺膜,实现DNA酶的固定。考察了不同DNA序列对传感器性能的影响,表明电化学与光学传感过程具有不同序列响应。此传感器对H2O2的检出限为2.2μmol/L;线性范围为0.01～1.5 mmol/L。本研究证实了利用聚多巴胺固定酶和用DNA酶代替天然酶构筑传感器的可行性。

The complex of G-quadruplex-hemin,also named peroxidase-mimicking DNAzyme,shows a catalytic activity towards hydrogen peroxide,which is rarely used as a catalyst in the assembly of electrochemical biosensors.Meanwhile,it is of significance to develop novel method in immobilizing DNA for the purpose of fabrication of DNA-based biosensors.Dopamine can form polydopamine film via self-polymerization.In this study,an electrochemical hydrogen peroxide biosensor was successfully constructed using polydopamine-entrapped G-quadruplex-hemin DNAzyme.The mixture of DNA and hemin achieved the formation of G-quadruplex-hemin complex.After the physical adsorption of DNAzyme on the glassy carbon electrode,a droplet containing 5 g/L dopamine in PBS（pH 8.0） was cast onto the surface.Ambient oxygen in the air oxidized dopamine for the formation of polydopamine to retain DNAzyme.The influence of DNA sequence to electrochemistry was investigated,showing a different phenomenon to optical sensors.The proposed biosensor was sensitive to hydrogen peroxide with the linear range spans the concentration from 10 μmol/L to 1.5 mmol/L and the limit of detection of 2.2 μmol/L.The results demonstrated the possibility of enzyme immobilization on the electrode through polydopamine and the substitution of G-quadruplex-hemin DNAzyme for natural enzyme.