AFM cantilevers (PNP‐TR‐20, Nanoworld, Switzerland) were used to measure neutravidin‐biotin binding forces. Prior to measurements, cantilevers were functionalized with PEG‐biotin (QBD10200, Sigma‐Aldrich, MO, USA)[82
] and treated using oxygen plasma at 600 mTorr and 100 W for 10 min. For forming amino groups, cantilevers were immersed in a 5% APTMS and absolute ethanol solution for 12 h. After rinsing with toluene, cantilevers were incubated in 1 mg ml−1 PEG‐biotin in chloroform with 0.5% trimethylamine catalysts for 2 h. Neutravidin‐biotin binding forces were measured using an AFM (NX‐10, Park systems) under 0.1 µm −1s in a PBS more than 50 points.
] and treated using oxygen plasma at 600 mTorr and 100 W for 10 min. For forming amino groups, cantilevers were immersed in a 5% APTMS and absolute ethanol solution for 12 h. After rinsing with toluene, cantilevers were incubated in 1 mg ml−1 PEG‐biotin in chloroform with 0.5% trimethylamine catalysts for 2 h. Neutravidin‐biotin binding forces were measured using an AFM (NX‐10, Park systems) under 0.1 µm −1s in a PBS more than 50 points.
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