Dendritic Structures As Photo-responsive Monolayers And Double Shell Structures As Unimolecular Nonocarriers

In this paper, we have studied two kind dendric macromolecules with different structures. These contents were divided into two parts to say, i.e., photo-responsive azobenzene-dendron monolayers, and dendritic double shell structures as unimolecular nanocarriers.In the first part, we prepared azobenzene dendron (with generations of 1-4) monolayers on Au or quartz substrates by DCC-catalyzed surface amidation reactions between the carboxyl acid group at the focal point of the dendrons and surface amine groups. IRRAS, UV–vis. absorption and Raman were performed to characterize these azobenzene dendron monolayers. Photo-isomerization of the monolayers of the dendron of four generations (G-4) was studied by using UV–vis. spectra, and was found to obey by the first-order kinetics. The thickness of the G-4 monolayers at different isomer forms were measured by using ellipsometry spectra, i.e., 23.8±0.9 ? at trans-form, and 18.8±0.8 ? at cis-form. The interaction between G-4 monolayers in different isomer forms and proteins with different isoelectric points (pI) was studied by using SPR whose results demonstrated that G-4 monolayers had a negative-charged surface that preferentially adsorbed positive-charged proteins, and the surface potential of the dendron monolayers became more negative when the monolayers changed from trans-form to cis-form.In the second, novel amphiphilic hyperbranched-upon-hyperbranched polymers with star-shaped core, and a hydrophilic hyperbranched polymer outer shell have been prepared. Hyperbranched polyesters (G2) with 16 hydroxyl end groups were used as the macroinitiators for the ring-opening polymerization ofε-CL to prepare G2-PCL star polymers. Then, the hyperbranched-upon-hyperbranched copolymers G2-PCL-HPGs were prepared by the ring-opening polymerization of glycidol initiated from the hydroxyl group of G2-PCL. The studies of G2-PCL-HPG unimolecular nanocarriers in water solution showed that G2-PCL-HPG unimolecular can well carry polar or no-polar molecules. And we demonstrated that indometacin-carried G2-PCL-HPG had the ability that can be controlled delivery in water.