Construction Of Three-dimensional Graphene-based Electrochemical Sensors And Detection Of Biological Small Molecules

Because of its large specific surface area,excellent mechanical properties and good electrical properties,graphene is considered to be a revolutionary material in the future and owns promising applications in biosensors,energy storage,adsorption and other fields.However,biosensors sensor own the advantages of high sensitivity,easily operable,cost effective and quick response,which show a promising application prospect in many aspects.Combing with the graphene materials,not only enriched the sensor electrode modified material,but also build unique electrochemical sensor,the performance of small molecules in the detection and diagnosis has got rapid development.In this study,three-dimensional graphene oxide(3D-G)and nitrogen-doped three-dimensional graphene(3D-NG)were synthesized successfully,and we use it to build series of graphene based electrochemical biosensors for quantitative detection of ascorbic acid(AA),dopamine(DA),uric acid(UA)and acetaminophen(AP),the contents are summarized as follows:(1)Based on the synthetic graphene oxide(GO)which under the induction of ethylenediamine(EDA)and the cross-linking of saturated sodium tetraborate(SBS),further through hydrothermal reaction in the reaction kettle.Then,3D-G hydrogels were obtained by dialysis and freeze-drying.Then,based on 3D-G hydrogel,and urea as the nitrogen source and reducing agent.After further hydrothermal reaction,3D-NG was obtained through freeze-drying.In addition,TEM,SEM,Raman,XRD,XPS and electrochemical detection were used to characterize the above materials.The results showed that although both 3D-G and 3D-NG had uniform three-dimensional porous structure,3D-NG showed better electrochemical performance and could be used as a good electrode for sensor construction.(2)3D-G dispersed in N,N-dimethylformamide(DMF)was added to the surface of the glassy carbon electrode,and 3D-G-based electrochemical sensor platform was constructed after natural drying.The electrochemical behaviors of AA,DA,UA and AP on 3D-G electrochemical sensor were systematically investigated.Due to more active sites of 3D-G,the peak potential differences of AA,DA,UA and AP were all above 0.083 V in DPV detection,and the peaks could be effectively distinguished.For individual detection of AA,DA,UA and AP on 3D-G/GCE,the linear ranges for AA,DA,UA and AP are 500-8000,20-800,20-1000 and 5-800 ?M with detection limits of 91.2,4.1,4.2 and 1.1 ?M(S/N=3),respectively.For simultaneous detection,the corresponding linear ranges for AA,DA,UA and AP are 300-5000,40-500,60-400 and 40-400?M with detection limits of 61.2,8.2,12.1 and 8.2 ?M(S/N=3).The 3D-G nanocomposites have promising applications in highly sensitive and selective electrochemical sensing.(3)3D-NG dispersed in DMF was added to the surface of the glassy carbon electrode,and 3D-NG electrochemical sensor platform was constructed after natural drying.Because doped nitrogen atoms can bond with carbon atoms in graphene and open the energy band gap of graphene,more active sites are provided for subsequent electrochemical detection,further improving the detection performance of the sensor.According to the experimental results,compared with 3D-G-based electrochemical sensors,3D-NG-based electrochemical sensors have a wider linear range and lower detection limit when detecting AA,DA,UA and AP separately and simultaneously.Due to more active sites of 3D-NG,the peak potential differences of AA,DA,UA and AP were all above 0.080 V in DPV detection,and the peaks could be effectively distinguished.When conducting individual detection,the linear ranges for AA,DA,UA and AP of 3D-NG-based electrochemical sensor are 20-10000,1-1000,0.5-1000 and 0.1-600 ?M and the detection limits are 3.91,0.26,0.12 and 0.02 ?M(S/N=3),respectively.For simultaneous detection,the corresponding linear ranges for AA,DA,UA and AP are 100-7000,2-600,1-800 and 10-550 ?M with detection limits of 24.33,0.37,0.21 and 1.87 ?M(S/N=3).Therefore,this sensor has greater application potential in the design of electrochemical sensors capable of simultaneous detection.