Research On The Electrochemical Immunosensor For Highly Specific Detection Of Bioactive Substances In Vivo Based On The Nanocomposite Materials

With the continuous research and development in the field of electrochemical sensors,it has become more and more widely used in the medical field.As a kind of electrochemical biosensor,immunosensor has the advantages of specificity,high sensitivity,simple operation,etc.It has become a new ideal technique for biomarkers analysis.Through the continuous improvement of nanotechnology,electrocatalytic nanocomposites and nano-metal materials are widely used because of their unique electrochemical properties and good biocompatibility in the construction of immunosensors.Given these advantages,we constructed two kinds of electrochemical immunosensor for the determination of leptin(LP)and pentrxin-3(PTX-3)in serum.Glassy carbon electrodes(GCE)were modified by functionalized single-walled carbon nanotubes/chitosan composites(COOH-SWCNTs/CS),functionalized multi-walled carbon nanotubes/gold nanowires composites(COOH-MWCNTs/AuNWs)and other materials,respectively.Detailed are as follows: 1.A sensitive leptin immunosensor based on functionalized singlewalled carbon nanotubes/chitosan nanocompositesThis work shows a novel immunosensor platform based on a simple nanocomposite(COOH-SWCNTs/CS)for the ultrasensitive detection of leptin.Label-free detection of LP was accomplished by differential voltammetry technique(DPV)that demonstrated a good linear response within 0.01-1000 ng/mL with a minimum detection limit of 5 pg/mL(S/N=3).The proposed immunosensor was also successfully applied in detecting LP in human serum samples and the present results showed no significant difference from classical enzyme-linked immunosorbent assay(ELISA)results.The single-walled carbon nanotubes(SWCNTs)are dispersed into the chitosan(CS)solution to form a stable complex.Compared with pure SWCNTs,CS makes it more uniform and stable.A fixed amount of leptin is captured by the complex(SWCNTs/CS)directly applied to the surface of the electrode and then competed with free LP to bind anti-LP,subsequently react with primary anti-LP antibody with alkaline phosphatase(ALP)-labeled anti-rabbit immunoglobulin G(secondary antibody),and utilize ALP and reaction with the substrate(Diethanolamine,DEA)to produce an electrochemical signal.Therefore,the immunosensor constructed in this experiment is a potential alternative for the clinical detection of LP,and it presents considerable application potential in future clinical and experimental analyses.2.An efficiently pentraxin-3 immunosensor based on functionalized multi-walled carbon nanotubes/gold nanowires nanocompositesIn this study,we used a novel electrochemical immunosensor platform based on nanocomposites formed by multiwalled carbon nanotubes(MWCNTs)and Au nanowires(AuNWs)for ultrasensitive detection of PTX-3 in serum.Quantitative detection of PTX-3 antigen was achieved by DPV technique,and this immunosensor showed good detection performance.It had a wide detection range(0.001-1000 ng/ml),a low detection limit(0.16 pg/ml),good selectivity,repeatability,and stability.Therefore,it can potentially be used for efficient detection in clinical settings.MWCNTs and AuNWs are closely integrated by physical complexation.Compared with pure MWCNTs,nanocomposites have higher electrochemical activity,and functionalized carbon nanotubes can combine more biomolecules.Through the antigen and antibody specific identification roles,a simple one-step method that can detect the antigen concentration was used without further labeling.