Study On Electrochemiluminescence DNA Sensor Based On Molecular Group Sensitization And Poly (Aniline-luminol)

The electrochemiluminescence method has the advantages of high sensitivity,high precision and wide detection range.As a commonly used electrochemiluminescence reagent,luminol is favored by researchers because of its advantages such as low cost and easy preparation.In this paper,luminol was used as electrochemiluminescence reagent,and luminescent functional materials based on poly(aniline-luminol)nanomaterials were synthesized by electrochemical and chemical oxidation methods,respectively.Based on the electrochemiluminescence signal amplification effect of ferrocene(Fc)and gold nanoparticles(Au NPs)on luminol,ferrocene cluster@gold nanoparticles molecular groups with strong sensitization to luminol were synthesized.Combined with the high specificity and conformational change of molecular beacons,two kinds of electrochemilumine-scence DNA sensors with high specificity and high sensitivity were developed.The main research contents are as follows:1.Poly(aniline-luminol)nanowires were synthesized on electrode surface by direct electrochemical synthesis.6-ferrocenylhexanethiol were attached on gold nanoparticles/streptavidin conjugates with Au-S bond to form ferrocene molecular cluster@gold nanoparticles(Fc@Au NPs).Then a biotinylated molecular beacon probe was attached onto Fc@Au NPs through streptavidin-biotin interaction.Then Fc@Au NPs@MB was modified on poly(aniline-luminol)nanowires by aldehyde ammonia condensation reaction.Because Fc@Au NPs was close to the surface of the electrode,it could effectively catalyze the electrochemiluminescence reaction of luminol.When the special Fc@Au NPs@MB reactd with the target DNA and then changed its structure,ECL intensity changed.Under the optimal conditions,the difference of ECL intensity before and after the hybridization reaction was linearly related to the concentration of the complementary sequence in the range of 1.0×10^-8?1.0×10^-14 mol·L^-1,and the detection limit was down to 4.4×10^-15 mol·L^-1.2.Poly(aniline-luminol)/CoC₂O₄ nanocomposites were synthesized by chemical oxidation.Based on the composites,two electrochemiluminescence DNA sensors based on"signal off"were prepared and used to detect Salmonella typhimurium.The first kind of electrochemiluminescence DNA sensor uses poly(aniline-luminol)/CoC₂O₄ as the electrochemiluminescence functionalized nano interface and Fc@MB as the electrochemiluminescence intensity controller.When the special Fc@MB reacts with the target DNA and changes its structure,the electrochemiluminescence intensity changes.Under the best experimental conditions,the linear range of the sensor is 1.0×10^-13?1.0×10^-7 mol L^-1,and the lowest detection limit is 3.79×10^-14 mol·L^-1.The second kind of electrochemiluminescence DNA sensor uses poly(aniline-luminol)/CoC₂O₄ as the electrochemiluminescence functionalized nano-interface and Fc@Au NPs@MB as the electrochemilumine-scence intensity controller.When Fc@Au NPs@MB reacts with the target DNA,the electrochemiluminescence intensity of the system changes.Under the optimum experimental conditions,the linear range of the sensor is 1.0×10^-15?1.0×10^-9mol L^-1,and the detection limit is 4.78×10^-16 mol·L^-1.This experiment once again proves that Fc@Au NPs is of practical significance and extensive in reducing the detection limit of the sensor,which can broaden the idea for the construction of electrochemiluminescence DNA sensor based on luminol signal amplification.