Generally, in clinical diagnosis of various conditions, ELISA is used for the immunologic analysis of bioactive substances such as the cytokines. For this reason, immunologic analysis methods are indispensable in dentistry. However, conventional immunoassays such as ELISA have some limitations, such as complicated procedures, extended analysis time, and the quantity of the sample needed. With the development of biomicrosensing technology, an experiment to measure bioactive substance is made possible by using an extremely small sample. The author developed an immunosensor that utilizes dielectric polarization and examined its clinical application in the field of dentistry. A sensor electrode coated with an insulation layer packed with immobilized antibody molecules was fabricated for microsensing. This appliance detects any difference in density as a change in voltage as soon as even an extremely small sample is placed on the sensor cell. The film which shows the change in voltage is called a response film.
The author investigated the followings: first, a material with an insulation property that is suitable for placing over the sensor electrode;second, a suitable time and density for antibodies to be immobilized on the insulation layer;third, the detection of mouse IgG antigen with a sensor which has been immobilized by an anti-mouse IgG antibody;fourth, the detection of various cytokines (IL-1α, IL-1β and TNF-α).
Firstly, it was revealed that a surface-etched film with SiO₂ particles into an insulation layer was most suitable for the response film. Secondly, it was also revealed that an antibody density of at least 100μg/ml, and an immobilization of time at least 30 minutes was best suited for the response film. Under these optimal conditions, the proposed immune sensor immobilized anti-mouse IgG on the insulation layer and exhibited a good electrochemical reaction towards mouse IgG. When the inflammatory mediators IL-1α, IL1-β, and TNF-α were measured, the sensor showed a good electrochemical reaction for each of the cytokines with differing voltages.
The present immunosensor utilizing specific polarization is able to evaluate antigen-antibody reactions as a voltage change and shows a strong potential for future use in clinical laboratory procedures.