title: A self-amplified transistor immunosensor under dual gate operation: highly sensitive detection of hepatitis B surface antigen.
abstract: Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor based on a self-amplified transistor under dual gate operation (immuno-DG ISFET) for the detection of hepatitis B surface antigen. To address the challenges in current ISFET-based immunosensors, we have enhanced the sensitivity of an immunosensor by precisely tailoring the nanostructure of the transistor. In the pH sensing test, the immuno-DG ISFET showed superior sensitivity (2085.53 mV per pH) to both standard ISFET under single gate operation (58.88 mV per pH) and DG ISFET with a non-tailored transistor (381.14 mV per pH). Moreover, concerning the detection of hepatitis B surface antigens (HBsAg) using the immuno-DG ISFET, we have successfully detected trace amounts of HBsAg (22.5 fg mL(-1)) in a non-diluted 1× PBS medium with a high sensitivity of 690 mV. Our results demonstrate that the proposed immuno-DG ISFET can be a biosensor platform for practical use in the diagnosis of various diseases.
authors.affiliation: Center for Biomaterials, Biomedical Research Institute, Korea Institute of Science and Technology (KIST), 5 Hwarang-ro 14-gil, Seongbuk-gu, Seoul 136-791, Republic of Korea. kwanhyi@kist.re.kr.
authors.forename: I-K
authors.initials: IK
authors.lastname: Lee
authors.forename: M
authors.initials: M
authors.lastname: Jeun
authors.forename: H-J
authors.initials: HJ
authors.lastname: Jang
authors.forename: W-J
authors.initials: WJ
authors.lastname: Cho
authors.forename: K H
authors.initials: KH
authors.lastname: Lee
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods*; D006509:Hepatitis B / Q000175:diagnosis* / Q000276:immunology; D006514:Hepatitis B Surface Antigens / Q000032:analysis* / Q000276:immunology; D006515:Hepatitis B virus / Q000737:chemistry* / Q000276:immunology; D014173:Transistors, Electronic
chemical_list: D006514:Hepatitis B Surface Antigens