We describe a rapid, sensitive, and label-free method to detect interferon-gamma (IFN-γ), a biomarker of latent tuberculosis infection (LTBI). IFN-γ is detected by measuring the capacitance change caused by its binding to an anti-IFN-γ antibody. The antibody is immobilized on the surface of an anodized aluminum oxide (AAO)-based capacitive sensor. With this technique, IFN-γ can be detected in the range of ~0.1. pg/ml to ~10. ng/ml, with a detection limit of 0.2. pg/ml. We have also measured the concentration of IFN-γ in clinical samples using the AAO-based capacitive sensor and compared this concentration with the results of the commercial QuantiFERON-TB Gold (QFT-G) ELISA kit to determine whether the two sets of data are consistent. Comparable results were obtained with the two measurement strategies, demonstrating the applicability of the AAO-based capacitive sensor to the diagnosis of LTBI.
Bibliographical noteFunding Information:
This work was financially supported by MEST through the National Research Foundation (NRF) of Korea (Nos. 2011-0017486, 2012R1A4A1029061, and 2011-0017611) and by Korea Center for Disease Control and Prevention ( 2012E4600700 ).
All Science Journal Classification (ASJC) codes
- Biomedical Engineering