earticle

영어

A capacitive biosensor was developed for the medical diagnosis of menginitis by detection of S100B protein in the patient cerebrospinal fluid (CSF). S100 protein is a calcium-binding protein and consists of two monomers, and it is overproduced during gliosis in patients with Alzheimer disease, Down syndrome and related dementia. Therefore, overproduction of S100B protein was reported to implicate the developmental brain dysfunction. In this work, a capacitive biosensor based on chronoamperometry was applied for the detection of S100B protein. For the improvement of the capacitive biosensor, the outer membrane (OM) layer with autodisplayed Z-domains was used to immobilize anti-S100B protein. In the previous work, we reported that the immunoaffinity layer based on the OM layer could far improve the sensitivity and limit of detection of immunoassays through the orientation control of the immobilized antibodies. For the
comparison of sensitivity, different immunoaffinity layers were prepared: self-assembled
monolayer (SAM) of 11-mercaptoundecanoic acid combined with covalent coupling of anti-S100B antibodies, physical adsorption of antibodies to the electrode surface. The immunoassay by using the OM layer with Z-domains showed the limit of detection was improved as much as 100-fold higher than the conventional SAM. For the capacitive sensor based on the OM layer with autodisplayed Z-domains, a standard curve at the S100B protein concentration of 1 pg/ml – 10 ng/ml was prepared by using standard samples by spiking S100B protein to CSF. The feasibility of the capacitive biosensor for the medical diagnosis was confirmed by comparison with the test results (n=20) from the conventional immunoassay.