A specific microgravimetric immunobiosensor for monitoring insulin concentration

We have developed a microgravimetric immunobiosensor for the determination of insulin concentration. The system consisted of a modified piezoelectric quartz crystal having bound to its electrode surface an antibody specific to insulin molecules. The antibody to insulin was covalently immobilized on the modified crystal surface via a direct protein A-gold immobilization method using dimethyl pimelimidate (DMP) as the cross linker. The antibody immobilized via the avidin-biotin immobilization method showed low sensitivity and poor stability of the immune biosensor system. Tests of the activity of the resulting immobilized antibody, uniformly oriented using the protein A-gold immobilization method, indicated that surface density close to the theoretical maximum (close packed) was achieved. A comparison between the present study and the well established radioimmunoassay (RIA) revealed that the described microgravimetric immunoassay technique could be developed as a potential alternate to RIA.