Reactive oxygen species have drawn attention owing to their strong oxidation ability. In particular, the singlet oxygen ( 1 O 2 ) produced by energy transfer is the predominant species for controlling oxidation reactions efficiently. However, conventional 1 O 2 generators, which rely on enhanced energy transfer, frequently suffer from poor solubility, low stability, and low biocompatibility. Herein, we introduce a hyperbranched aliphatic polyaminoglycerol (hPAG) as a 1 O 2 generator, which relies on spin-flip-based electron transfer. The coexistence of a lone pair electron on the nitrogen atom and a hydrogen-bonding donor (the protonated form of nitrogen and hydroxyl group) affords proximity between hPAG and O 2 . Subsequent direct electron transfer after photo-irradiation induces hPAG •+ -O 2 •– formation, and the following spin-flip process generates 1 O 2 . The spin-flip-based electron transfer pathway is analyzed by a series of photophysical, electrochemical, and computational studies. The 1 O 2 generator, hPAG, is successfully employed in photodynamic therapy and as an antimicrobial reagent.

Functional hyperbranched polyglycerols (PGs) have recently garnered considerable interest due to their potential in biomedical applications. Here, we present a one-pot synthesis of hyperbranched PGs possessing amine functionality using a novel amino glycidyl ether monomer. A Boc-protected butanolamine glycidyl ether (BBAG) monomer was designed and polymerized with glycidol (G) through anionic ring-opening multibranching polymerization to yield a series of hyperbranched P(G-co-BBAG) with controlled molecular weights (4800-16700 g/mol) and relatively low molecular weight distributions (1.2-1.6). The copolymerization and subsequent deprotection chemistry allow the incorporation of an adjustable fraction of primary amine moieties (typically, 5-20% monomer ratio) within the hyperbranched PG backbones, thus providing potentials for varying charge densities and functionality in PGs. The copolymerization kinetics of G and BBAG was also evaluated using a quantitative in situ C NMR spectroscopic analysis, which revealed gradient copolymerization between the comonomers. The free amine groups within the deprotected P(G-co-BAG) copolymer were further utilized for a facile conjugation chemistry with a model molecule in a quantitative manner. Furthermore, the superior biocompatibility of the prepared P(G-co-BAG) polymers was demonstrated via cell viability assays, outperforming many existing polyamines possessing relatively high cytotoxicity. Taken together, the biocompatibility with facile conjugation chemistry of free amine groups sheathed within the framework of hyperbranched PGs holds the prospect of advancing biological and biomedical applications.

We report a one-pot synthesis of hyperbranched polyglycerols possessing amino functionality by using a novel Boc-protected aminoethanol glycidyl ether monomer (BAG). A series of hyperbranched Boc-protected polyamino glycerols (PBAG) were prepared through a one-pot anionic ring opening multibranching polymerization to yield PBAG with controlled molecular weights (3500-17400 g/mol). Subsequent deprotection of PBAG yielded hyperbranched polyamino glycerols (PAG) with a globular polymeric structure that comprises a randomly branched structure with a large number of functional amine and hydroxyl groups. 1 H, 13 C, and 15 N-NMR, GPC, and MALDI-TOF measurements confirmed the successful polymerization of the hyperbranched PAG polymers. With its superior biocompatibility of PAG, we anticipate the prospective potentials for the applications in biological and biomedical fields.