Photochemical microcontact printing by thiol-ene and thiol-yne click chemistry

This article describes the microstructured immobilization of functional thiols on alkene- and alkyne-terminated self-assembled monolayers on silicon oxide substrates by photochemical microcontact printing. A photochemical thiol-ene or thiol-yne “click” reaction was locally induced in the area of contact between stamp and substrate by irradiation with UV light (365 nm). The immobilization reaction by photochemical microcontact printing was verified by contact angle measurements, X-ray photoelectron spectroscopy, atomic force microscopy, and time-of-flight secondary ion mass spectrometry. The reaction rate of photochemical microcontact printing by thiol-ene chemistry was studied using time dependent contact angle measurements. The selective binding of lectins to galactoside microarrays prepared by photochemical microcontact printing was also demonstrated. It was found that photochemical microcontact printing results in a high surface coverage of functional thiols within 30 s of printing even for dilute (mM) ink solutions.