Photo-induced hydrogen-bonding complexes for drug periodic release.

The construction of intelligent supramolecular nanocarriers has received much attention for their potential application in chemotherapy. Herein, we report the successful design and synthesis of a photoreactive monomer, N'-(2-nitrobenzyl)-N-acryloyl glycinamide (NBNAGA). Using a poly(ethylene glycol) (PEG)-based macro-RAFT agent, the amphiphilic diblock copolymer (BCP), PEG-b-PNBNAGA, was prepared through a reversible addition-fragmentation chain-transfer (RAFT) polymerization. Then, photoresponsive polymeric micelles (PMs) were fabricated with the hydrophilic PEG shielding coronas and hydrophobic PNBNAGA inner cores via the self-assembly of PEG-b-PNBNAGA BCPs. Upon 365 nm UV light irradiation, the o-nitrobenzyl groups in the micellar cores were removed with freshly formed amide moieties. 1. Combined with the original amide moieties dual hydrogen bond interactions in the side chains came into being, subsequently changing the PMs' cores from hydrophobic to hydrophilic. Thus, the photo-induced dual hydrogen-bonding complex rather than a hydrophobic interaction assembly with inviable nanostructures was achieved, which gave rise to the first stage of doxorubicin (DOX) release. During the second period, the noncovalent cross-linked PMs underwent further structural disintegration upon heating with dissociation of the dual hydrogen bonds, resulting in the sequential DOX release. In other words, periodic drug release was successfully accomplished via a photoirradiation-induced mechanism modification of micellar cores formation and then by subsequent heating-induced hydrogen-bonding complex disruption, thus indicating its promise for use in therapeutics synergistic delivery in severe disease therapy.