An ultrasensitive label-free electrochemical impedimetric immunosensor for vascular endothelial growth factor based on specific phage via negative pre-screening

As a vascular growth regulator, vascular endothelial growth factor (VEGF) exerts significant biological roles through specific binding to its receptors on the vascular endothelial cells. VEGF165 is generally referenced as a potential therapeutic target of many malignant tumors. In this study, a negative pre-screening strategy with structurally analogous members of VEGF121, VEGFC and VEGFD was first proposed for VEGF165 biopanning, aiming at significantly improving the specificity of the selected phage monoclones. Indirect ELISA experiment showed that the phage monoclone expressing peptide SPFLLRM demonstrates excellent affinity and specificity. Then a VEGF165 electrochemical impedimetric spectroscopy (EIS) immunosensor was constructed by above specific phage modified electrode. After optimizing the experimental conditions, the as-explored EIS immuno-sensor had a linear range of 0.5-1000 pg/mL with the limit of detection of 0.15 pg/mL VEGF165. In addition, the developed phage-based EIS immunosensor was applied to satisfactorily detect VEGF165 in human serum sam-ples. Considering its ultra-sensitivity, good selectivity, batch reproducibility and stability, the screened selective phage-based EIS sensor is envisioned potential application in diagnosis and therapy.

Automated summary

In this study, a negative pre-screening strategy was proposed to improve the specificity of selected phage monoclonal antibody clones for VEGF165 biopanning. The developed phage-based EIS immunosensor showed excellent affinity and specificity for VEGF165, and it had a linear range of 0.5-1000 pg/mL with a limit of detection of 0.15 pg/mL. This selective phage-based EIS immunosensor has potential applications in diagnosis and therapy.