Development of a label-free impedance biosensor for detection of antibody-antigen interactions based on a novel conductive linker
Journal
Biosensors and Bioelectronics
Journal Volume
26
Journal Issue
6
Pages
3072-3076
Date Issued
2011
Author(s)
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. © 2010 Elsevier B.V.
Type
journal article