Fabrication Of Photo-controlled Silicon Surfaces Based On Inclusion Complexation Between β-Cyclodextrin And Azobenzene

Surface modification based on host-guest chemistry has aroused great interests in the past few years. Here, we describe a new strategy for the preparation of a functional silicon wafer surface with photo-controlled reversibility based on host-guest chemistry between β-cyclodextrin and azobenzene.1. Triethoxysilane-terminated azobenzene derivative (Azo-PTES) was firstly synthesized via copper-catalyzed azide-alkyne "click chemistry" between propargyl azobenzene derivative and (3-azidopropyl) triethoxysilane. The silicon wafer was first modified with the guest molecule Azo to form Azo-terminated silicon wafer (Si-Azo) surface via a silanization reaction; subsequently, a series of polymers with different polarities including poly(ethylene glycol)(PEG), polymethyl methacrylate (PMMA) and poly(methyl methacrylate β-co-hexafluorobutyl methacrylate)(P(MMA-co-HFBMA)) were attached to the host molecule β-cyclodextrin (β-CD) to prepare β-CD-containing hemi-telechelic polymers via "click chemistry". The photo-controlled silicon wafer surfaces with polymers were finally constructed via inclusion complexation between β-CD and Azo, and the wettability of the substrate is dependent on the polymers we used. The elemental composition, surface morphology and the hydrophilic/hydrophobic property of the modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscope (AFM), contact angle (CA) measurements, respectively. The antifouling properties of poly(ethylene glycol)(PEG) functionalized surfaces were evaluated by a protein adsorption assay using bovine serum albumin (BSA).2. We had constructed β-CD-based sensors for detecting Hg2+in aqueous media. β-cyclodextrin-terminated rhodamine derivative (β-CD-SRhB) was synthesized firstly, which shows a high selectivity and sensibility for detecting Hg2+β-CD-SRhB was further used to construct photo-controlled solid-state sensors for detecting Hg2+via inclusion complexation between β-CD and Azo.