Multi-responsive poly(amidoamine)-initiated dendritic-star supramolecular structures containing UV cross-linkable coumarin groups for smart drug delivery

Dendritic-star supramolecular structure of poly(amidoamine)-g-[polystyrene-b-(2-(dimethylamino)ethyl methacrylate-co-11((4-methyl-2-oxo-2H-chromen-7-yl)oxy)undecyl acrylate)] (PAMAM-g-P(St-b-(DMAEMA-co-CuA))) was synthesized via grafting-from atom transfer radical polymerization (ATRP) by using PAMAM-initiator as smart drug carrier. This structure consisted of multi-responsive unites of hydrophilic PDMAEMA regarding to pH change, temperature, and CO2 gas and the coumarin molecule as photocrosslinking agent. Photocrosslinking agent is efficient for controlling DOX release after dimerization under UV light. The chemical structure of samples was confirmed by proton nuclear magnetic resonance (H-1 NMR) and their molecular weight was studied by gel permeation chromatography (GPC). The change of hydrophilic length of PDMAEMA and pH media resulted in various morphologies induding hollow sphere, snowman- and dumbbell-like particles. The morphology of supramolecular assemblies was not changed after photocrosslinking, which confirmed the structure stabilization under UV light irradiation of 365 nm. Fluorescence microscopy was confirmed the presence of fluoresce segments in self-assembled supramolecular structures. Dynamic light scattering (DLS) indicated that the size of supramolecular assemblies was changed through the response to external stimuli such as pH, temperature, and CO2 gas. The DOX release behavior was investigated in different conditions such as pH, temperature, and after photocrosslinking under UV light of 365 nm. (C) 2020 Elsevier B.V. All rights reserved.