基于Fe3O4-Au磁性纳米粒子的双酚A电化学发光适配体传感器研究

In this paper, magnetic Fe3O4 nanoparticles were prepared by chemical coprecipitation method. Silicon dioxide layer is coated on the surface of Fe3O4 nanoparticles, and then the magnetic particles was functionalized with amino groups. Core shell composites of Fe3O4@SiO2@Au were prepared by electrostatic adsorption between the negatively charge gold nanoparticles (AuNPs) and positively charged protonated amino groups of the magnetic nanoparticles. The laboratory self-made magnetic glassy carbon electrodes (MGCE) were used as basic electrodes and Fe3O4@SiO2@Au composites were modified onto the surface of the electrodes. Double stranded DNA (dsDNA) was synthesized by hybridization between bisphenol A aptamers (Apt) functionalized with amino and thiol functionalized complementary DNA chains (cDNA) of bisphenol A aptamer. CdS quantum dots (QDs) functionalized with carboxyl groups were prepared. The covalent bonds were formed between the amino group of Apt in dsDNA and the carboxyl group of CdS QDs to prepare dsDNA-CdS. The dsDNA-CdS was modified the surface of above-mentioned electrode by forming Au-S chemical bonds to prepare bisphenol A aptamer sensor (denoted as MGCE/Fe3O4@SiO2@Au-dsDNA-CdS). After being bound with bisphenol A, the aptamer and the connected CdS QDs will fall off from the electrode surface. The electrochemiluminescence (ECL) signals of bisphenol A aptamer sensor showed a good linear relationship with bisphenol A concentration in the range of 0.100 nmol/L ~ 10.0 μmol/L, with a detection limit of 0.08 nmol/L. The experimental results indicated that the aptamer sensor for bisphenol A possesses both good selectivity and high sensitivity.