Preparation And Electrochemical Sensing Applications Based On Functional Carbon Material And Single-stranded DNA

The development of nanomaterials stimulates scientists to study them by electrochemical analysis due to their excellect electrical propertie.In this paper,the electrochemical detection is based on the construction of electrochemical sensing of functionalized carbon materials or deoxyribonucleotides sensing for biomolecules.Functional carbon material not only preserving casid properties,but also owing the functional properties.Deoxyribonucleic acid plays an extremely important role in genetic material.DNA as an electrochemical biosensing material for small molecules is becoming an important issue,because of its high specificity and sensitivity.The first part of this paper is the applicating functional carbon material composite midified electrode to detect small molecules.Another part of the paper is using deoxyribonucleotides(DNA)as a sensing material to analysis small molecules.The reaearch works are summarized as follow:1.amino-reduced graphene oxide(NH2-rGO)/β-cyclodextrin(β-CD)that were self-assembled on the surface of a glassy carbon electrode(GCE)by drop-casting method,and characterized by static contact angles,cyclic voltammetry and electrochemical impedance spectroscopy.The detection of Cu(II)was used SWASV.Under optimum experimental conditions,the modified GCE exhibited excellent SWASV response in the concentration of Cu(II)in the 30 nM to 100 μM range.The limit of detection is 2.8 nM(at 3σ/slope).The modified GCE displaying good reproducibility,is stable,highly sensitive and selective.It was successfully applied to the determination of Cu(II)in real water samples.2.Using N-doped carbon dots/β-cyclodextrin nanocomposites modified glassy carbon electrodes(N-CDs/β-CD/GCE)to enantioselective recognice tryptophan(Trp)enantiomers.The nano composite was characterized by SEM,FT-IR,FL and XPS.The electrochemical behavior of Trp on N-CDs/β-CD composite modified electrode was studied by DPV.Such N-CDs/β-CD/GCE generated a significantly lower Ip and more negative Ep in the presence of L-Trp in DPVs,which was used for the enantioselective recognition of Trp enantiomers.The N-CDs/β-CD nanocomposites showed different binding constants for tryptophan enantiomers,and they further selectively bonded with L-Trp to form inclusion complexes.This strategy provided the possibility of using a nanostructured sensor to discriminate the chiral molecules in bioelectroanalytical applications.3.The electrochemical behavior of Asp on GCE was studied by DPV contain Trp solution.The fomation of Trp and Asp via hydrophobic interaction.Different potential voltammogram was employed to interact between Asp and Trp.The influences of buffer、pH and temperature for Trp-Asp complex were discussion.For the first time,different oxidation peak potentials(Ep)of Asp were observed in the differential pulse voltammograms obtained in the solution containing tryptophan(Trp).Further study showed that the Ep of that peak shifted positively and linearly with an increasing concentration of Asp.The detection limits of Asp was 3×10-5 M.4.This biosensor was prepared by effective self-assembling process of thiol group functionalized single-stranded DNA(ssDNA)on the surface of gold electrode(GE)through specific Au Scovalent bond,and characterized with CV and EIS.The ssDNA/GE showed a single strong DPV oxidation peak,which was used as the electrochemical signal for AA sensing.The bonding interaction between AA and ssDNA was confirmed by UV–vis absorption spectrometry and DPV.Under optimum conditions,ssDNA/GE exhibited excellent DPV response depending on the concentration of AA in 0.4–200μM range.The limit of detection was 8.1 nM(3α/slope).This electrochemical biosensor displayed good reproducibility and high stability.This electrochemical platform is convenient and efficient,offering great potential for construction of electrochemical biosensors toward various toxic substances.