Versatile, Highly Controlled Synthesis of Hybrid (Meth)acrylate–Polyester–Carbonates and their Exploitation in Tandem Post‐Polymerization–Functionalization

Aluminum Salen Complexes Modified with Unsaturated Alcohol: Synthesis, Characterization, and Their Activity towards Ring-Opening Polymerization of ε-Caprolactone and D,L-Lactide

A highly efficient one-step approach to the macromonomer synthesis using modified aluminum complexes as catalysts of ring-opening polymerization (ROP) of ε-caprolactone and D,L-lactide was developed. The syntheses, structures, and catalytic activities of a wide range of aluminum salen complexes, 3a-c, functionalized with unsaturated alcohol (HO(CH₂)₄OCH=CH₂) are reported. X-Ray diffraction studies revealed a tetragonal pyramidal structure for 3c. Among the complexes 3a-c, the highest activity in bulk ROP of ε-caprolactone and D,L-lactide was displayed by 3b, affording polyesters with controlled molecular weights at low monomer to initiator ratios (M_n up to 15,000 g mol^-1), relatively high polydispersities (Ð~1.8) and high number-average functionalities (F_n up to 85%).

N-Hydroxyethyl acrylamide as a functional eROP initiator for the preparation of nanoparticles under "greener" reaction conditions

N-Hydroxyethyl acrylamide was used as a functional initiator for the enzymatic ring-opening polymerisation of ε-caprolactone and δ-valerolactone. N-Hydroxyethyl acrylamide was found not to undergo self-reaction in the presence of Lipase B from Candida antarctica under the reaction conditions employed. By contrast, this is a major problem for 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate which both show significant transesterification issues leading to unwanted branching and cross-linking. Surprisingly, N-hydroxyethyl acrylamide did not react fully during enzymatic ring-opening polymerisation. Computational docking studies helped us understand that the initiated polymer chains have a higher affinity for the enzyme active site than the initiator alone, leading to polymer propagation proceeding at a faster rate than polymer initiation leading to incomplete initiator consumption. Hydroxyl end group fidelity was confirmed by organocatalytic chain extension with lactide. N-Hydroxyethyl acrylamide initiated polycaprolactones were free-radical copolymerised with PEGMA to produce a small set of amphiphilic copolymers. The amphiphilic polymers were shown to self-assemble into nanoparticles, and to display low cytotoxicity in 2D in vitro experiments. To increase the green credentials of the synthetic strategies, all reactions were carried out in 2-methyl tetrahydrofuran, a solvent derived from renewable resources and an alternative for the more traditionally used fossil-based solvents tetrahydrofuran, dichloromethane, and toluene.

Antimicrobial Hyperbranched Polymer-Usnic Acid Complexes through a Combined ROP-RAFT Strategy

Polymer-drug conjugates have received considerable attention over the last decades due to their potential for improving the clinical outcomes for a range of diseases. It is of importance to develop methods for their preparation that have simple synthesis and purification requirements but maintain high therapeutic efficacy and utilize macromolecules that can be cleared via natural excretory pathways upon breakdown. Herein, the combination of ring-opening polymerization (ROP) and reversible addition-fragmentation chain-transfer (RAFT) polymerization is described for the straightforward synthesis of amphiphilic, stimuli-responsive, biodegradable, and highly functionalizable hyperbranched polymers. These unimolecular nanoparticles demonstrate a versatile platform for the synthesis of polymer-drug conjugates owing to the inclusion of a Boc-protected polycarbonate moiety in either a block or random copolymer formation. A proof-of-concept study on the complexation of the poorly water-soluble antimicrobial drug usnic acid results in polymer-drug complexes with powerful antimicrobial properties against gram-positive bacteria. Therefore, this work highlights the potential of amphiphilic and biodegradable hyperbranched polymers for antimicrobial applications.

Enhancing doxorubicin anticancer activity with a novel polymeric platform photoreleasing nitric oxide

Combination of Doxorubicin with light-regulated NO release achieved through formulation strategy of tailored polymeric conjugate nanoparticles may open new treatment modalities to improve cancer therapies.