Immunosensor incorporating half-antibody fragment for electrochemical monitoring of amyloid-β fibrils in artificial blood plasma.

In this report, an electrochemical immunosensor for the selective and sensitive monitoring of Aβ1-42 fibrils is presented. The sensing platform was prepared by the formation of a 4,4'-thiobisbenzenethiol (TBBT) self-assembled monolayer on a clean gold surface followed by the covalent entrapment of gold nanoparticles (AuNPs). The half-antibody fragments of the Anti-Amyloid Fibrils antibody were immobilized on AuNPs via S-Au covalent bonds. Each step of immunosensor fabrication was characterized with cyclic voltammetry and electrochemical impedance spectroscopy. The biosensor was successfully used for the sensing of Aβ1-42 fibrils in both phosphate saline buffer (PBS) and artificial blood plasma (ABP). The immunosensor sensitivity estimated based on calibration slopes was better in the presence of APP in the comparison to PBS. The LOD values obtained for both measuring media were of 0.6 pM level. The moderate response towards Aβ1-42 oligomers demonstrated the immunosensor selectivity.