Deflection cantilever detection of interferon gamma

Interferon-gamma (IFN-γ) is a biomarker protein and an indicator of relapse in multiple sclerosis (MS) patients. Treatment of diseases and conditions like MS may be time sensitive, and deflection cantilevers are a promising platform for real-time measurement of biomarker proteins. Additionally, linking procedures have a substantial effect on the sensitivity of deflection cantilever measurements. Therefore, successful detection of IFN-γ using three different linking procedures is presented. Enzyme-linked immunosorbent assays were used to confirm the efficacy of the linking procedures before they were implemented on cantilever deflection arrays. The steady state change in surface stress due to IFN-γ binding was determined to be 0.16 ± 0.09, −0.11 ± 0.04 and −0.08 ± 0.06 N/m for the glutaraldehyde, Prolinker B and 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC)/N-hydroxysulfosuccinimide (Sulfo-NHS) linking procedures, respectively. Furthermore, R2 values near 1 indicate good correlation between an exponential model for antibody–antigen binding and cantilever deflection. Steady state deflection of 667.3 ± 0.1, −452.0 ± 0.0, and −406.2 ± 0.2 nm and rate constants of 0.4582 ± 0.0003, 0.4737 ± 0.0000 and 0.1766 ± 0.0002 1/h were calculated for the glutaraldehyde, Prolinker B and EDC/Sulfo-NHS linking procedures, respectively.