Construction And Application Of Electrochemical Biosensor Based On Carbon Nanomaterials

The electrochemical biosensor is a promising device for detection and diagnosis.It has the advantages of high sensitivity,high specificity,continuous online detection,low requirement on turbidity,and no complicated pretreatment process.However,with the increase in demand,the electrochemical biosensor is faced with the problem s of limited recognition receptors and low sensitivity.In this paper,two kinds of electrochemical biosensors were constructed using novel recognition receptors and different carbon nanomaterials as electrode support materials.They were used for the first detection of linear microcystin toxin(L-MC-LR)and high sensitivity detection of lung cancer biomarker gastrin-releasing peptide(Pro GRP).After proving the feasibilities of the sensors,the experimental conditions were optimized.The analysis performance of the constructed biosensors was tested under the optimal conditions.We come to the following conclusions:(1)The degrading enzyme Mlr B can specifically degrade L-MC-LR,and Mlr B is used as a recognition receptor for the first time.Multi-walled carbon nanotube(MWCNT)has a large specific surface area and high electrical conductivity,which can not only amplify the signal but also improve the load rate of M lr B.Therefore,MWCNT is used as the electrode support material.Based on this,an electrochemical biosensor was prepared for the first concentration detection of L-MC-LR.The functionalized MWCNT-COOH was characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier transform infrared spectroscopy(FT-IR),Raman spectroscopy(Raman),and X-ray photoelectron spectroscopy(XPS).The results show that there are a lot of oxygen-containing functional groups on the surface,and the struct ure is complete without obvious defect or fracture.After the feasibility was demonstrated by cyclic voltammetry(CV),the constructed sensor was used to detect L-MC-LR under optimal conditions.The detection range was 1 pg/m L-100 ng/m L,and the limit of detection was 0.127 pg/m L(S/N=3).The results showed good selectivity,reproducibility,and time stability.A satisfactory recovery rate was also shown when the lake water samples were tested.(2)Three-dimensional carbon nanomaterials 3D-rGO@Au were synthesized as electrode support material,and sandwich electrochemical immunosensors were prepared by using antibodies as recognition receptors for high sensitivity detection of Pro GRP.First,3D-rGO@Au was characterized by SEM,TEM,FT-IR,Raman,XPS,and X-ray energy spectroscopy(EDS).The analysis showed that the chip was a three-dimensional porous spatial network structure,which had larger effective specific surface area than two-dimensional graphene and could load more antibodies.Electrochemical data show that it has high electrical conductivity.The sandwich structure amplifies the signal so the sensor has high sensitivity.Compared with the reported sensor for Pro GRP detection,the prepared sensor has obvious advantages in detection range(1 fg/m L-10 ng/m L),the limit of detection(0.136 fg/m L(S/N=3)),sensitivity,selectivity,preparation reproducibility,and long-term stability under the optimal experimental conditions.The sensor also showed a good recovery rate when testing serum samples.