An anchoring strategy for photoswitchable biosensor technology: Azobenzene-modified SAMs on Si(111)

Reviews and Highlights	Quantum Science	Molecular and Soft-matter	Ultrafast Nano-optics and Nanophotonics	Mineralogy and Geochemistry

Paul Dietrich , Fabian Michalik , Richard Schmidt , Cornelius Gahl , Guoqiang Mao , Markus Breusing , Markus B. Raschke, Beate Priewisch, Thilo Elsässer, Robert Mendelsohn, Martin Weinelt, and Karola Rück-Braun
Appl. Phys. A 93, 285 (2008).
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A mild and efficient procedure has been developed to obtain covalently attached self-assembled monolayers (SAMs) on Si(111) with photochromic azobenzene head-groups. Starting from neat or diluted carboxylic acid functionalized monolayers on-chip coupling reactions were applied to attach hydroxyl-functionalized azobenzene units to the SAMs by ester bond formation. The modified surfaces were characterized by high-resolution X-ray photoelectron spectroscopy (XPS), transmission Fourier transform infrared spectroscopy (FT-IR), and contact angle measurements. Reversible cis ↔ trans isomerizations of photoswitchable SAMs were monitored by wettability measurements.