Multicyclic topology-enhanced anticancer drug delivery.

Inspired by the biological use of a combination of precision and self-assembly to achieve exquisite control and diversity from 20 natural amino acids, there is considerable scope for the development of synthetic precision materials with complex architecture that can access advanced function for biomedical applications. Single cyclic polymers (SCPs) have been shown to offer different and often better performance compared to their linear analogues. Because multicyclic topology in nature offers enhanced effects relative to single cyclization, we hypothesize that multicyclic polymers (MCPs) would access unique features compared to SCPs. However, there are currently quite limited ways to efficiently synthesize MCPs and to precisely modulate the valency of cyclic units. In this work, we report for the first time a straightforward and robust strategy to synthesize MCPs with controllable valency via facile one-pot statistical reversible addition-fragmentation chain transfer (RAFT) copolymerization. We use this strategy to synthesize biocompatible MCPs based on the most classic and important biocompatible polymers of oligo (ethylene glycol) (OEG) and cyclic poly(ε-caprolactone) (cPCL), which can further self-assemble into well-defined nanostructures. We then apply these MCP-based formulations as drug delivery vehicles and demonstrate greater colloidal stability with a low critical micelle concentration (CMC) of 80.3 nM, larger drug loading capacity, higher cellular uptake efficiency, more tumor accumulation, and increased anti-tumor efficacy in murine tumor models compared to SCP-based analogues. We believe this cumulative work demonstrating facile synthesis of MCPs and demonstration of multicyclic topology-enhanced anti-cancer efficiency in vivo provides key technologies and concepts to the burgeoning field of cyclic topology-derived biomaterials.

Expanding Cyclic Topology-Based Biomedical Polymer Panel: Universal Synthesis of Hetero-"8"-Shaped Copolymers and Topological Modulation of Polymer Degradation.

8-Shaped copolymers with two macrocycles connected together represent an interesting cyclic topology-derived polymer species due to the simultaneous incorporation of two cyclic moieties and the reported unique physical and chemical properties. To provide a proof-of-concept for a broad readership on biomedical polymers, a well-defined hetero-8-shaped amphiphilic copolymer, cyclic-poly(oligo(ethylene glycol)monomethyl ether methacrylate)-b-cyclic PCL (cPOEGMA-b-cPCL) is synthesized by an elegant integration of intrachain click cyclization and interchain click coupling. The potential of the self-assembled micelles of cPOEGMA-b-cPCL for controlled drug release is evaluated by in vitro drug loading and drug release, cellular uptake, cytotoxicity, and degradation studies. Most importantly, the micelles based on cPOEGMA-b-cPCL show much slower degradation profiles than the previously reported linear counterpart, POEGMA-b-PCL and tadpole-shaped analog, PEG-b-cPCL because of the presence of cyclic hydrophilic POEGMA segment. Therefore, this study not only develops a robust strategy for a universal precise synthesis of well-defined hetero-8-shaped copolymers based on diverse vinyl and ring-structured monomers, but also reveals the first modulation of polymer degradation property by topological control of the nondegradable moiety in the polymer construct through advanced macromolecular engineering.