Construction and transmembrane dissociation behavior of supramolecular assembly of quinolinocyclodextrin with porphyrin

Through the stoichiometric 2 : 1 coordination of Zn2+ with 4-amino-N-(2-methylquinolin-8-yl)benzenesulfonamide-modified per-methyl-beta-cyclodextrin (MQAS-PMCD) and the strong inclusion complexation of permethyl-beta-cyclodextrin cavity with meso-tetrakis-(4-sulfonatophenyl)-porphyrin (TSPP), an environment-sensitive Zn2+/cyclodextrin/porphyrin triad supramolecular assembly was constructed, and its structure was fully characterized by UV/vis spectroscopy, fluorescence spectroscopy, powder X-ray diffraction (XRD), scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). Fluorescence spectrometric studies showed that this supramolecular assembly was stable and barely emitted green fluorescence in water due to the energy transfer process, but gave the strong green fluorescence when changing to a hydrophobic environment due to the disruption of the assembly. Further studies on the cell staining experiments by means of fluorescence microscopy showed that this supramolecular assembly was disrupted to release the MQAS-PMCD/Zn2+ and porphyrin components when interacting with the cell membrane. Subsequently, the released MQAS-PMCD/Zn2+ complex remained in the cell membrane, while the porphyrin component entered the cells. This transmembrane dissociation property of the supramolecular assembly will enable its application in the delivery of biological and drug molecules containing the anionic porphyrin skeleton such as beta-octaphenyl-meso-tetra(4-carboxyl)-phenylporphyrin and so on.