Synthesis and Self-Assembly of o -Nitrobenzyl-Based Amphiphilic Hybrid Polymer with Light and pH Dual Response

Abstract

In this paper, novel light‐responsive polyhedral oligomeric silsesquioxane (POSS) end‐capped poly(o‐nitrobenzyl methacrylate) (POSS–PNBMA) are synthesized by the combination of atom transfer radical polymerization (ATRP) and click chemistry. After subsequent partial photocleavage of PNBMA yielding poly(methacrylic acid) (PMAA), pH‐ and light‐responsive random copolymer of POSS–P(NBMA‐co‐MAA) is obtained. The o‐nitrobenzyl‐based amphiphilic hybrid polymer can self‐assemble into spherical micelles in aqueous solution. Hydrophobic POSS and PNBMA segments aggregate into the inner core, and the hydrophilic PMAA chains tend to stretch from the core. The micellar morphology can be tuned by pH changes and UV irradiation. Light irradiation leads to the transformation of P(NBMA‐co‐MAA) into PMAA and to the reorganization of the assemblies, causing the release of encapsulated guest molecule Nile Red into water. This dual‐responsive polymer has a broad potential use in targeted drug delivery.

Temperature and Photo Dual‐Stimuli Responsive Block Copolymer Self‐Assembly Micelles for Cellular Controlled Drug Release

“…[ 27 ] The hydrophobic trans‐ form of the azobenzene transforms into the strong polar cis‐ form under UV irradiation, and the tight cores of regular trans‐ form azobenzene with an ordered array transforms to the cis‐ form, which packs into the loose cores as an unordered array, leading to an increased micelle size from 125 to 210 nm with the average size approaching to be about 165 nm. [ 14,19 ] As expected, though the polarity of side azo moieties on the hydrophobic block shifts the hydrophilic–hydrophobic balance, it is not enough to destabilize or dissociate the micelles. [ 27,48 ] Therefore, spherical nanoparticles remain observable from TEM photographs after UV irradiation, but the micelle cores become fluffy due to the increased hydrophilicity and swelling of the chain segments.…”

“…Therefore, it is very necessary for us to engineer dual‐ and/or multi‐stimuli responsive copolymer drug carriers for tracking these signal changes and more effective drug release. [ 14 ] Pan et al developed temperature and pH dual sensitive smart hydrogels by crosslinking PNIPAM with dimethylaminoethyl methacrylate (PDMAEMA). [ 15 ] PNIPAM can be made to have light and temperature dual sensitive properties by incorporating photosensitive groups or molecules such as azobenzenes, stilbenes, spiropyrans (SPA), spirooxazines fulgides, and diarylethenes into the end groups or side chains of PNIPAM.…”

“…[ 15 ] PNIPAM can be made to have light and temperature dual sensitive properties by incorporating photosensitive groups or molecules such as azobenzenes, stilbenes, spiropyrans (SPA), spirooxazines fulgides, and diarylethenes into the end groups or side chains of PNIPAM. [ 14,16–18 ] Light‐responsive materials receive particular attention in many research fields including biomedicine as light sources are safe, clean, easy to use, and controlled. [ 19 ] Many researchers reported dual‐/tri‐/multi‐responsive random and/or block copolymers consisting of photo‐responsive SPA and temperature‐, pH‐ and/or CO 2 ‐ sensitive segments because of the quick response rate and reversible isomerization of SPA molecules.…”

Thermosensitive and photocleavable polyaspartamide derivatives for drug delivery

“…It can be seen from Figure that the transparent colorless aqueous solution of NB ‐g‐ PHPA‐3, irradiated under UV light at 365 nm and at low temperature such as 2 °C (below the CP), gradually turned into light yellow with the increase of irradiation time. The same aqueous solution became opaque at a higher temperature such as 35 °C (above the CP), which turned gradually into more transparent with light yellow after UV light irradiation …”

Polymerization of a Photocleavable Monomer Using Visible Light

“…As a result, there have been limited reports on the polymerization of NBMA using controlled radical polymerization techniques with a high degree of polymerization control. A more systematic and controlled polymerization of this monomer is therefore desirable due to its potential application in the field of light‐responsive polymeric materials …”