Reactivity and kinetics of vinyl sulfone-functionalized self-assembled monolayers for bioactive ligand immobilization

A new vinyl sulfone (VS) disulfide, 1,2-bis(11-(vinyl sulfonyl)undecyl)disulfane, was synthesized to enable the preparation of VS-presenting self-assembled monolayers (VS SAMs) on Au substrates. The VS SAMs were used as a model system to assess the reaction kinetics of bioactive ligands, i.e., glutathione (GSH), N-(5-amino-1-carboxypentyl)iminodiacetic acid (ab-NTA), and mannose, toward the VS groups on the SAM surface. The VS SAMs and the ligand immobilization were characterized by X-ray photoelectron spectroscopy (XPS), contact angle goniometry, and protein-binding experiments using a quartz crystal microbalance (QCM). Kinetic studies showed that the surface VS groups undergo pseudo-first-order reactions with various ligands, with the observed rate constant being 0.057 min(-1) for GSH at pH 7.5, 0.011 min(-1) for ab-NTA at pH 8.5, and 0.009 min(-1) for mannose at pH 10.5. This work advanced our understanding of the reactivity of VS-bearing functional surfaces and further demonstrated the versatile potential of VS chemistry to prepare ligand-immobilized bioactive surfaces.