Membrane surface functionalization via theophylline derivative coating and streptavidin immobilization

• Modification of membrane surfaces by using bioactive materials.
• Theophylline derivative as an alternative to biotin for monitoring streptavidin interaction.
• Easy procedure for monitorization of the protein interaction by bright field microscopy.

Poly(vinylidene fluoride) (PVDF) and regenerated cellulose (RC) membranes were surface-modified by the adsorption of one adenosine receptor antagonist: the theophylline-oligo(ethylene glycol)-alkene derivative, Theo1. Surface modification was carried out by immersion of the membrane in a dichloromethane solution of Theo1 (PVDF + Theo1 and RC + Theo1 samples). Membrane surfaces with partial coverage by theophylline and/or its inclusion in the membrane structures were studied by X-ray photoelectron spectroscopy (XPS), solid-state nuclear magnetic resonance (SNMR), impedance spectroscopy (IS) and contact angle (CA) measurements. The Theo1 orientation was inferred from the data. Streptavidin (SA) was immobilized onto the membrane/Theo1 hybrid material. The protein–theophylline Theo1 interaction was visualized with bright field microscopy (BFM).

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