Research On Electrochemical Immunosensor Based On Anti-opal Structure And Graphene Composite Materials

Due to asymptomatic nature of the most kind of cancer,effective determination of tumor biomarkers is very important for the early diagnosis,evaluating the extent of disease,and pharmacological response to therapeutic intervention.Tumor markers are generally produced or released by cancerous cells,and are generally lower in normal people than in cancer patients.Thus,sensitive detection of tumor marker is of great importance in clinical research for cancer patients screening and diagnosing.Among different technologies,label–free electrochemical immunosensor has attracted much attention in tumor marker tracking,because of its high-accuracy,easy operation,simplicity,cheapness and high biocompatibility.Especially it can be directly used to monitor the binding process of antibody(Ab)–antigen reaction and avoid disturbances from conjugated markers or handling with hazardous materials.As is known,electrode material is the most essential component in label–free electrochemical immunosensor which needs better conductivity and larger specific surface area of electrode so as not to hinder the electron transfer and to immobilize more antibodies.From this view,great efforts have been made to enhance the detection sensitivity and/or obtain low detection limits through exploring different sensing materials,such as noble metal or carbon based immunosensor.Our recent work about immunosensor based on Au nanorods and IrO_x wire-in-tube nanofibers also successfully obtained highly improved sensing behavior to AFP.However,although the effective surface area has been considerably improved through adjusting the nanostructure and the composition of the sensing materials,it is still a challenge to obtain further improved sensing behavior due to the inflexible of traditional electrode.For instance,in the case of glass carbon electrode(GCE)which is the most widely used electrode in electrochemical sensing,it generally needs to print the nano-object slurry onto its conductive substrate to form a film in the typical produce.This doubtless has limited the variety of nanomaterials on the electrode surface and the carrying capacity for material modified(9 mm~2 working area),and as consequence discounts the performance of the immnuosensor.Therefore,in the present work,we have focused on the three-dimensional ordered IrO_x photonic crystal and graphene composite materials,which modified in fluorine doped tin conductive glass(FTO).(1)Being a special kind of nanostructure,3DOM material with controllable microporous has become a promising strategy for sensing applications and also has been considered to enhance the performance of an individual electrode,due to its periodic structure,high surface area,easily controlled pore size,as well as interconnected macrospores.Thus,the advantages of using such 3DOM architecture to construct sensing electrodes are manifold:the highly open and interconnected macrospores architecture effectively shortens the diffusion pathways for mass transport,and is also very helpful of increasing conductivity.Meanwhile,a larger interfacial area can make target analyses molecules readily access,thus obtain an improvement in the apparent reaction rate,as well as the accuracy of alpha-fetoprotein(AFP)detection was also enhanced in human serum.At 500 degrees the 3DOM IrO_x were synthesized,we obtained the optimal structure and sensor performance of the immune sensor.(2)In addition,we did some extension work.We used the improved hummers method to synthesize reduced graphene oxide(rGO),the AuNRs are made from seeds,and AuNRs are modified into rGO and spun onto FTO.Thanks to the high specific surface area,chemical stability,biocompatibility and high mechanical strength of rGO,and high conductivity of AuNRs,we prepared an electrochemical immunosensor based on Au NRs/rGO,for test the prostate specific antigen(PSA).