DNA Sensor Based On Polyaniline And Three-dimensional Reduced Graphene Oxide

In this work,a new type of DNA electrochemical sensor was established to detect breast cancer susceptibility gene BRCA1.Breast cancer is the most frequently diagnosed among women and affects their health globally.The early and precise detection of breast cancer BRCA1 biomarker is of great importance in facilitating diagnosis and improving the cure rate.In this work,a label-free DNA biosensor based on three-dimensional reduced graphene oxide（3D-rGO）and polyaniline（PANI）nanofibers modified glassy carbon electrode（GCE）was successfully developed for supersensitive detection of breast cancer BRCA1.First,GO was prepared by the Hummers’method using flake graphite,then3D-GO was obtained through a one-step hydrothermal method,and finally reduced with hydrazine hydrate.Using aniline polymerization to prepare polyaniline nanofibers（PANI）,ultrasonically treat the two materials,and obtain 3D-rGO-PANI nanocomposites byπ-πconjugated non-covalent bonding.Analyze and verify the surface morphology,composition,and bonding methods of materials through a series of characterizations such as SEM,TEM,XPS and so on.The electrochemical behaviors of 3D-rGO-PANI/GCE were investigated by cyclic voltammetry（CV）,differential pulse voltammetry（DPV）and electrochemical impedance spectroscopy（EIS）methods.The results demonstrated that 3D-rGO and PANI nanofibers had synergic effects for reducing the charge transfer resistance（Rct）and enhance electronic transmission capabilities,meaning a huge enhancement in electrochemical activity of 3D-rGO-PANI/GCE.Under optimum conditions(ssDNA fixation for 10 h,hybridization time of 40minutes,temperature of 37℃,pH of 7.4,MB concentration of 2.0×10^-5 M,incubation for 25 min)investigated by DPV,probe DNA（ssDNA）could be immobilized on the 3D-rGO-PANI/GCE for special and sensitive recognition of target DNA(1.0×10^-15～1.0×10^-7 M)through forming double strand DNA（dsDNA）,with a theoretical LOD of 3.01×10^-16 M.At the same time,the DNA sensor specificity,stability and repeatability are in line with expectations.Furthermore,this proposed nano-biosensor could directly detect BRCA1 under the interference of real blood samples.