A reversible light-responsive assembly system based on host–guest interaction for controlled release

Abstract

Here, we established a reversible light-responsive assembly system, which consisted of azobenzene grafted mesoporous silica nanoparticles (MSN–AZO) and cyclodextrin-functionalized Au nanoparticles (AuNP@CD). The assembly system was constructed by the host–guest interaction between azobenzene and β-cyclodextrin. For controlled release, the cargo molecule fluorescein isothiocyanate (FITC) in the pores of the MSNs can be regulated or triggered by different wavelengths. Under visible light irradiation, the azobenzene on the MSN surface exhibits a trans-configuration, and can bind with β-cyclodextrin on the AuNPs by host–guest interaction. Thus the mesopores were closed by the AuNP@CD caps and cargo molecules were locked in the pores. While under UV irradiation, the azobenzene changed to cis-configuration, which cannot bind with β-cyclodextrin, leading to the disaggregation of the caps from the outer surface of the MSNs. Thus the cargo molecules were released from the pores. This light-responsive triggered system may have potential applications in drug-controlled release, light-responsive devices and novel catalytic processes.