Construction Of GO/AuNPs Composite-Based Electrochemical Sensor And Its Application In Detection Of DNA Or Cadmium Ions

Many reports suggested that graphene oxide metal nanoparticles composites has become an interesting material with application prospect in the field of electrochemical,due to the advantages of its unique structure,excellent performance,simple preparation process and easy to operate.For GO-based nanocomposites,the unique properties of the GO nanosheets make them particularly useful as the nanoparticle support.This is because the high surface area is essential for the dispersion of the nanoparticles and in order to maintain their electrochemical activities.At the same time,the GO-supporting materials not only maximize the availability of the nanosized surface area for electron transfer but also provide better mass transport of the reactants to the electroactive sites on the electrode surface.Moreover,the conductive GO support facilitates the efficient collection and transfer of electrons to the collecting electrode surface.And GO-based nanopartical composite-modified electrodes present unusual advantages over ordinary GO-based composite-modified electrodes in electrochemical applications.These include excellent catalytic activity,enhancement of mass transport,a high effective surface area,and control over the electrode microenvironment.Bea use of its unique physicalchemical properties,Graphene oxide nanoparticles composite structure owns synergy in many reactions,which gives it great advantages in sensing applications.Remarkably,when the special structure of graphene oxide nanoparticles composites was applied in sensors,not only show their own characteristic,but also show their synergy.Their synergy does not exist when they were applicated separately.So the compound can be applied to various kinds of sensing mechanism,in order to imp rove the sensitivity and selectivity of chemical sensor.As we know,when introduce a different molecule to the graphene oxide nanoparticles composites,the properyies of graphene oxide nanoparticles composites will change.By this way,we can design different materials to detect different target.Based on this,this paper carries out the following two specific research work:?1?Using a one-pot strategy synthesized ternary reduced graphene oxide-Hemin-Au?rGO-H-Au?nanohybrids by simply heating the mixed solution of GO,hemin and HAuCl₄ under alkaline conditions,without adding any additional surfactant,stabilizing agent and reducing agents.The synthesized composite can catalyze H₂O₂,in this compound,GO was reduced to rGO.rGO act as a supporting material,which overcame the disadvantages of Hemin insoluble in water and inhibited the aggregation of AuNPs.Because of single-stranded DNA and rGO can work together through?-stacking interactions between nucleotide bases and the rGO surface,which inhibit the catalytic activity of the rGO-H-AuNPs composite.When in the presence of targets,the single-stranded DNA combineed with the targets away from the surface of the rGO-H-AuNPs composite,and the catalytic activity of rGO-H-AuNPs composite recoved.By replacing the single-stranded DNA,different targets can be detected.When specific DNA strands are detected,the DNA strand that binds to the rGO-H-AuNPs composite could be replaced with its complementary strand.When protein or cell is detected,the DNA strand that binds to the rGO-H-AuNPs composite could be replaced by an aptamer of protein or cell.Based on this,a novel electrochemical sensor based on rGO-H-AuNPs composite was constructed for detecting different targets.?2?A novel electrochemical sensor is proposed based on graphene oxide?GO?/gold nanoparticles?AuNPs?/tetraphenylporphyrin?TPP??GO/AuNPs/TPP?nanocomposite for the detection of cadmium ions(Cd²⁺).The sensing mechanism is based on acoordination interaction between metal cations and porph yrin.GO was employed to accelerate the incorporation of Cd²⁺and tetraphenylporphyrin.Besides,the AuNPs was introduced to enhance the sensitivity of electrochemical detection.Accordingly,the proposed electrochemical sensor showed high selectivity towa rd Cd²⁺over other mental ions(e.g.,Ca²⁺,Fe³⁺,Mg²⁺,etc.).Moreover,the sensor was further applied to determination of Cd²⁺in real water samples with satisfactory results.