Abstract
Most of reported polymeric light-responsive nanocarriers make use of UV light to trigger morphological changes and the subsequent release of encapsulated cargoes. Moving from UV- to visible-responsive units is interesting for the potential biomedical applications of these materials. Herein we report the synthesis by ring opening polymerization (ROP) of a series of amphiphilic diblock copolymers, into which either UV or visible responsive azobenzenes have been introduced via copper(I) catalyzed azide-alkyne cycloaddition (CuAAC). These copolymers are able to self-assemble into spherical micelles or vesicles when dispersed in water. The study of the response of the self-assemblies upon UV (365 nm) or visible (530 or 625 nm) light irradiation has been studied by Transmission Electron Microscopy (TEM), Cryogenic Transmission Electron Microscopy (Cryo-TEM), and Dynamic Light Scattering (DLS) studies. Encapsulation of Nile Red, in micelles and vesicles, and Rhodamine B, in vesicles, and its light-stimulated release has been studied by fluorescence spectroscopy and confocal microscopy. Appreciable morphological changes have been induced with green light, and the subsequent release of encapsulated cargoes upon green light irradiation has been confirmed.
Highlights
Over the last years, polymeric micelles and vesicles formed through the self-assembly of amphiphilic copolymers have deserved great interest as nanocarriers of therapeutic agents since their physicochemical properties and performance can be adjusted by fine-tuning of the polymers chemical structure [1,2]
We described a series of light responsive amphiphilic linear-dendritic diblock copolymers consisting of a linear hydrophilic segment of poly (PEG) linked to a 2,2-di(hydroxymethyl)propionic acid based dendron as the hydrophobic block whose periphery was decorated with azobenzenes [19,20]
The length of the hydrophilic segment has influence in the morphology of the self-assemblies, length of the hydrophilic segment has influence in the morphology of the self-assemblies, micelles micelles are formed for PEG113 -b-PCAzo23 and PEG113 -b-PCAzoOMe23, while PEG45 -b-PCAzo18 and are formed for PEG113-b-PCAzo and
Summary
Polymeric micelles and vesicles formed through the self-assembly of amphiphilic copolymers have deserved great interest as nanocarriers of therapeutic agents since their physicochemical properties and performance can be adjusted by fine-tuning of the polymers chemical structure [1,2]. In polymeric vesicles, which are larger in size, the hydrophilic chains assemble forming two coronas that face the internal aqueous cavity and the surrounding aqueous medium, with the hydrophobic chain separating them. These vesicular self-assemblies can be used for the encapsulation and transport of both hydrophilic and hydrophobic small molecules inside the hollow cavity or the bilayer, respectively. This encapsulation ability of micelles and vesicles can be exploited
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