Electrochemical Immunosensors Based On Ferrocene-tagged Peptide Nanomaterials

Because of its high sensitivity, rapid analysis, simple operation and low cost, electrochemical immunosensor has been developed rapidly in recent years and gradually applied in the fields of clinical diagnosis, food safety and environmental monitoring. Therefore, the future development of electrochemical immunosensor can be summarized as follows:preparing different types of electrochemical immunosensor to extend their applications, improving their detection sensitivity by combining nano-technology and achieving commercialization of electrochemical immunosensor.Herein, we introduce two novel electroactive peptides nanomaterials, i.e., ferrocene-peptide nanowire(Fc-PNW) and Fc-Phe-OH hydrogel. They were prepared by Fc-phenylalanine(Fc-Phe-Phe-OMe) and Fc-phenylalanine(Fc-Phe-OH) through self-assembly, respectively. Fc-PNW and Fc-Phe-OH hydrogel were used as mediators to build new electrochemical immunosensors and their electrochemical properties were studied. The main research work is as follows:Fc-Phe-Phe-OMe, which can self-assemble into Fc-PNW was synthesized and poly diallyldimethylammonium chloride(PDDA) was adsorbed onto its surface. Then, nano-Au particles(AuNPs) were immobilized onto the surface of PDDA coated Fc-PNW by electrostatic adsorption to capture detection antibody(Ab2) to form Fc-PNW-Ab2. Finally, amperometric immunosensor with the structure as Fc-PNW-Ab2/IgG/AuNPs-GN-Ab]/GCE was prepared through sandwich method. The electrochemical properties of the immunosensor were carefully explored by cyclic voltammetry (CV) and square wave voltammetry (SWV). The results show that the sensor has high sensitivity, good stability and selectivity. There was good linear relationship between IgG concentration and Fc-PNW redox peak current value in the IgG concentration range from10fg/mL to1ng/mL with a detection limit is5fg/mL. Moreover, the results of human serum recovery rate are between92.8%and96.3%, which are satisfied. Thus, the immnosensor has potential clinical applications and can also be applied in detecting other types of biomarkers.Fc-Phe-OH hydrogel that used as mediator to construct label-free electrochemical immunosensor for the detection of prostate specific antigen was prepared through self-assembly process. Glassy carbon electrode was modified with Fc-Phe-OH hydrogel, graphene incorporated chitosan, AuNPs and antibody sequentially. An amperometric immunosensor with structure of Fc-Phe-OH hydrogel/CS-GN-AuNPs/anti-PSA was constructed. The electrochemical performance of the sensor was studied carefully by CV and SWV. The data show that the immunosensor has high sensitivity, good stability and selectivity. Good linear relationship between PSA concentration and Fc-PNW redox peak current was obtained with PSA concentration in the range from1pg/mL to10ng/mL. The detection limit was calculated to be500fg/mL. The human serum recovery rate is between90.99%and108.2%, which is satisfied. The immunosensor has potential applications in clinical diagnosis and also can be used in detecting other types of biomarkers.