title: Development of a label-free impedance biosensor for detection of antibody-antigen interactions based on a novel conductive linker.
abstract: We developed a label-free impedance biosensor based on an innovative conductive linker for detecting antibody-antigen interactions. As the often used conventional long chain thiol is a poor conductor, it is not a suitable material for use in a faradaic biosensor. In this study, we adopted a thiophene-based conductive bio-linker to form a self-assembled monolayer and to immobilize the bio-molecules. We used cyclic voltammetry and impedance spectroscopy to verify the enhanced conductivity properties. Results showed that the electron transfer resistance of this new conductive linker was 3 orders of a magnitude lower than for a case using a conventional long chain thiol linker. With the decreased impedance (i.e. increased faradaic current), we can obtain a higher signal/noise ratio such that the detection limit is improved. Using fluorescence microscopy, we verified that our new conductive linker has a protein immobilization capability similar to a conventional long chain thiol linker. Also, using S100 proteins, we verified the protein interaction detection capability of our system. Our obtained results showed a linear dynamic range from 10 ng/ml to 10 μg/ml and a detection limit of 10 ng/ml. With our new conductive linker, an electrochemical impedance biosensor shows great potential to be used for point-of-care applications.
authors.affiliation: Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan.
authors.forename: Ching-Sung
authors.initials: CS
authors.lastname: Chen
authors.forename: Ku-Ning
authors.initials: KN
authors.lastname: Chang
authors.forename: Ying-Hua
authors.initials: YH
authors.lastname: Chen
authors.forename: Chih-Kung
authors.initials: CK
authors.lastname: Lee
authors.forename: Bryan Yong-Jay
authors.initials: BY
authors.lastname: Lee
authors.forename: Adam Shih-Yuan
authors.initials: AS
authors.lastname: Lee
mesh_terms: D055910:Antibodies, Immobilized; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions; D015374:Biosensing Techniques / Q000379:methods* / Q000706:statistics & numerical data; D002097:C-Reactive Protein / Q000032:analysis; D004553:Electric Conductivity; D017097:Electric Impedance; D055664:Electrochemical Techniques; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D055767:Immobilized Proteins; D008856:Microscopy, Fluorescence; D009418:S100 Proteins / Q000032:analysis; D012709:Serum Albumin / Q000032:analysis; D013876:Thiophenes
chemical_list: D055910:Antibodies, Immobilized; D055767:Immobilized Proteins; D009418:S100 Proteins; D012709:Serum Albumin; D013876:Thiophenes; D002097:C-Reactive Protein