No abstract

Delicate control over architectures via crystallization-driven self-assembly (CDSA) in aqueous solution, particularly combined with external stimuli, is rare and challenging. Here, we report a stepwise CDSA process thermally initiated from amphiphilic poly(N-allylglycine)-b-poly(Noctylglycine) (PNAG-b-PNOG) conjugated with thiol-terminated triethylene glycol monomethyl ethers ((PNAG-g-EG 3 )-b-PNOG) in aqueous solution. The diblock copolymers show a reversible thermoresponsive behavior with nearly identical cloud points in both heating and cooling runs. In contrast, the morphology transition of the assemblies is irreversible upon a heating− cooling cycle because of the presence of a confined domain arising from crystalline PNOG, which allows for the achievement of different nanostructured assemblies by the same polymer. We demonstrated that the thermoresponsive property of PNAG-g-EG 3 initiates assembly kinetically that is subsequently promoted by crystallization of PNOG thermodynamically. The irreversible morphology transition behavior provides a convenient platform for comparing the cellular uptake efficiency of nanostructured assemblies with various morphologies that are otherwise similar.

No abstract

Self‐assembled cationic polymeric nanostructures have been receiving increasing attention for efficient antibacterial agents. In this work, a new type of antibacterial agents is developed by preparing pH‐dependent nanostructured assemblies from cationic copolypeptoid poly(N‐allylglycine)‐b‐poly(N‐octylglycine) (PNAG‐b‐PNOG) modified with cysteamine hydrochloride ((PNAG‐g‐NH2)‐b‐PNOG) driven by crystallization and hydrophobicity of the PNOG blocks. Due to the presence of confined domains arising from crystalline PNOG, persistent spheres and fiber‐like assemblies are obtained from the same polymer upon a heating‐cooling cycle. This allows for direct comparison of antimicrobial efficiency of nanostructured assemblies with various morphologies that are otherwise similar. Both nanostructured assemblies exhibit extremely low toxicity to human red blood cells, irrespective of the presence of the hydrophobic block. Enhanced antimicrobial performance of the fiber‐like micelles compared to the spheres, which result in high selectivity of the fibers, is shown. Notably, the fiber‐like micelles show great efficacy in inhibition of the Staphylococcus aureus (S. aureus) biofilm formations and eradication of the mature biofilms, superior to vancomycin. The micelles also show potent in vivo antimicrobial efficacy in a S. aureus infection mouse skin model. With a systematic study, it is demonstrated that both micelles kill the bacteria through a membrane disruption mechanism. These results imply great potential of polypeptoid assemblies as promising excellent candidates for antibacterial treatment and open up new possibilities for the preparation of a new generation of nanostructured antimicrobials.

In this work, a series of PLGA-PEG diblock copolymers were synthesized by ring-opening polymerization of L-lactide and glycolide using mPEG as macroinitiator and stannous octoate as catalyst. Spherical micelles were obtained from the various copolymers by using co-solvent evaporation method. The biocompatibility of micelles was evaluated with the aim of assessing their potential in the development of drug delivery systems. Various aspects of biocompatibility were considered, including MTT assay, agar diffusion test, release of cytokines, hemolytic test, dynamic clotting time, protein adsorption in vitro, and zebrafish embryonic compatibility in vivo.The combined results revealed that the micelles present good cytocompatibility and hemocompatibility in vitro. Moreover, the cumulative effects of micelles throughout embryos developing stages have no toxicity in vivo. It is thus concluded that micelles prepared from PLGA-PEG copolymers present good biocompatibility as potential drug carrier.