Electrochemical Sensor For The Determination Of Dopamine Based On Carbon Dots

Based on the special properties of large surface area,high catalytic efficiency and multiple active sites of carbon dots,a series of carbon dots-based modified electrodes were prepared and used for the determination of dopamine(DA).Some novel electrochemical sensors for assaying of DA were' constructed.The main contents are as follows:(1)Carbon dots(CDs)and chitosan(CS)composite film modified glassy carbon electrode(CDs-CS/GCE)was prepared.The morphology of CDs was characterized by Transmission electron microscope(TEM),UV-vis absorption spectra and fluorescence spectra.The electrodes were characterized by atomic force microscope(AFM),cyclic voltammetry(CV)and electrochemical impedance spectra(EIS).Then the CDs-CS/GCE was applied to determine the biological molecules of dopamine(DA).Under the optimal conditions,the CDs-CS/GCE showed that it was better electrochemical response for the detection of DA than that of the glassy carbon electrode(GCE).Furthermore,CDs-CS/GCE exhibited good ability to suppress the background current from large excess ascorbic acid(AA)and uric acid(UA)due to the CDs had carboxyl and hydroxyl.The oxidation peak current(Ipa)of DA was linear with concentration of DA in the range from 0.1?M to 30.0 ?M with the limit of detection as 11.2 nM(3S/N).The CDs-CS/GCE was applied to the detection of DA content in injection solution of DA with satisfactory results,and the biosensor could keep its activity for at least two weeks.(2)A novel composite film of Au@carbon dots(Au@CDs)-chitosan(CS)modified glassy carbon electrode(Au@CDs-CS/GCE)was prepared simply and applied in the sensitive and reliable determination of dopamine(DA).The CDs had carboxyl groups with negative charge,which not only made it have good stability but also enables interaction with amine functional groups in DA through electrostatic interaction to multiply recognize DA with high specificity,and the Au nanoparticles could make the surface of the electrode more conductive.Comparing with the bare GCE,CS/GCE,Au-CS/GCE and CDs-CS/GCE electrodes,the Au@CDs-CS/GCE had higher catalytic activity toward the oxidation of DA.Furthermore,Au@CDs-CS/GCE exhibited good ability to suppress the background current from large excess ascorbic acid(AA)and uric acid(UA).Under the optimal conditions,selective detection of DA in a linear concentration range of 0.01 to 100.0?M was obtained with the limit of 0.001?M(3S/N).At the same time,The Au@CDs-CS/GCE also was applied to the detection of DA content in DA's injection with satisfactory results,and the biosensor could keep its activity for at least two weeks.(3)In this study,we developed and characterized a new dopamine(DA)sensor based on the reduced graphene oxide(rGO)-carbon dot composite film with high sensitivity,nice specificity and good stability.The carbon dots(CDs)had carboxyl groups with negative charge,which not only provided good stability,but also enabled interaction with amine functional groups in DA through electrostatic interaction to enhance the specificity of DA with high specificity,and the interaction and electron communication between rGO and DA can be further strengthened via ?-? stacking force.Under optimal conditions,the rGO-CDs electrode(GCE)showed better electrochemical response towards the detection of DA than the bare GCE,GO/GCE and CDs/GCE.A linear relationship between the oxidation peak current of DA and its concentration could be obtained in a range from 0.01 ?M to 450.0 ?M with the limit of detection as 1.5 nM(3S/N).Furthermore,rGO-CDs/GCE exhibited good ability to suppress the background current from large excess ascorbic acid(AA)and uric acid(UA).Meanwhile,the rGO-CDs/GCE also was applied to the detection of DA content in the injection of DA with satisfactory results,and the biosensor could keep its activity for at least six weeks.