The high incidence of bacterial infection and the growing resistance of bacteria to conventional antibiotics have resulted in the strong need for the development of new generation of antibiotics. Nano-sized particles have been considered as novel antibacterial agents with high surface area and high reactivity. The overall antibacterial properties of antimicrobial nanostructures can be significantly enhanced compared with conventional antibacterial agents not in a regular nanostructure, showing a better effect in inhibiting the growth and reproduction of microbials such as bacteria and fungi, etc. In this review, recent advances in the research and applications of antimicrobial polymeric nanostructures have been highlighted, including silver-decorated polymer micelles and vesicles, antimicrobial polymer micelles and vesicles, and antimicrobial peptide-based vesicles, etc. Furthermore, we proposed the current challenges and future research directions in the field of antibacterial polymeric nanostructures for the real-world biomedical applications.

Constructing artificial helical structures through hierarchical self-assembly and exploring the underlying mechanism are important, and they help gain insight from the structures, processes, and functions from the biological helices and facilitate the development of material science and nanotechnology. Herein, the two enantiomers of chiral Au­(I) complexes ( S )-1 and ( R )-1 were synthesized, and they exhibited impressive spontaneous hierarchical self-assembly transitions from vesicles to helical fibers. An impressive chirality inversion and amplification was accompanied by the assembly transition, as elucidated by the results of in situ and time-dependent circular dichroism spectroscopy and scanning electron microscope imaging. The two enantiomers could serve as ideal chiral templates to co-assemble with other achiral luminogens to efficiently induce the resulting co-assembly systems to show circularly polarized luminescence (CPL). Our work has provided a simple but efficient way to explore the sophisticated self-assembly process and presented a facile and effective strategy to fabricate architectures with CPL properties.

The efficient intracellular drug delivery is an important challenge due to the slow endocytosis and inefficient drug release of traditional delivery vehicles such as symmetrical polymer vesicles, which have the same coronas on both sides of the membrane. Presented in this paper is a noncytotoxic poly(ethylene oxide)-block-poly(caprolactone)-block-poly(acrylic acid) (PEO113-b-PCL132-b-PAA15) triblock copolymer vesicle with an asymmetrical structure. The biocompatible exterior PEO coronas are designed for stealthy drug delivery; The pH-responsive interior PAA chains are designed for rapid endosomal escape and enhanced drug loading efficiency. The hydrophobic PCL vesicle membrane is for biodegradation. Such asymmetrical polymer vesicle showed high doxorubicin (DOX) loading efficiency and good biodegradability under extracellular enzymatic conditions. Compared with three traditional symmetrical vesicles prepared from PEO113-b-PCL110, PEO43-b-PCL98-b-PAA25, and PAA21-b-PCL75 copolymers, the DOX-loaded asymmetrical PEO113-b-PCL132-b-PAA15 polymer vesicles exhibited rapid endocytosis rate and much faster endosomal escape ability, demonstrating promising potential applications in nanomedicine.

We have previously reported the preparation of a novel pH-sensitive and biocompatible polymer vesicle in pure water based on the spontaneous self-assembly of a diblock copolymer, PMPC-b-PDPA, where PMPC is poly[2-(methacryloyloxy)ethyl phosphorylcholine] and PDPA is poly[2-(diisopropylamino)ethyl methacrylate] (J. Am. Chem. Soc.200512717982). Herein, we intend to report the strategy for controlling the pH trigger points of association/dissociation of pH-responsive polymer vesicles for anticancer drug delivery. We introduced a reactive block, poly[2-(dimethylamino)ethyl methacrylate] (PDMA) into the above diblock copolymer to form reactive PMPC-b-PDMA-b-PDPA and PMPC-b-PDPA-b-PDMA triblock copolymers, as well as PMPC-b-P(DMA-stat-DPA) block-statistical copolymer by atom transfer radical polymerization (ATRP) in methanol at room temperature. As a result of different block length of PDPA, the introduction of PDMA chain at different positions, and different initial copolymer concentrations, those block copolymer vesicles showed tunable pH trigger points and various isoelectric points (IEPs) in aqueous solution. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) studies confirmed that the block copolymers with relatively long PDPA block form polymer vesicles by simply tuning the solution pH in pure water. Above pH 6.2, the PDPA block becomes hydrophobic so it forms the vesicle membrane. In all cases, the hydrophilic PMPC chains form the vesicle coronas. The PDMA chains are designed in three different positions. In PMPC-b-PDMA-b-PDPA vesicles, the PDMA chains form the middle shell between the PDPA vesicle membrane and the PMPC vesicle corona. In PMPC-b-PDPA-b-PDMA vesicles, the PDMA can mix with PMPC to serve as mixed coronas. In PMPC-b-P(DMA-stat-DPA) vesicles, the reactive PDMA chains can be incorporated into the vesicle membrane, which provides an effective strategy regarding the immobilization of vesicles by selective quaternization of PDMA with a bifunctional cross-linker, such as 1,2-bis(2-iodoethoxy)ethane (BIEE). The degree of cross-linking can be tuned by varying the molar ratio of PDMA to BIEE, which was further investigated by 1H NMR, DLS, and TEM, suggesting tunable permeability of vesicle membrane. The triblock copolymer vesicles were able to encapsulate anticancer drugs such as DOX, exhibiting obviously retarded release profile at physiological conditions.

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Traditional T 1 magnetic resonance imaging (MRI) contrast agents such as diethylenetriaminepentacetatic acid (DTPA) chelated gadolinium [Gd(III)] have poor sensitivity, leading to a risk of accumulated toxicity in vivo.To significantly improve the sensitivity of a T 1 MRI contrast agent and to enhance the efficacy of cancer chemotherapy, herein for the first time we report a noncytotoxic asymmetrical cancer targeting polymer vesicle based on R-poly(L-glutamic acid)-block-poly(ε-caprolactone) [R is folic acid (FA) or DTPA]. Such asymmetrical vesicles have a cancer-targeting outer corona and a Gd(III)-chelating and drug-loading-enhancing inner corona, exhibiting an extremely high T 1 relaxivity (42.39 mM −1 s −1 , 8-fold better than DTPA-Gd) and anticancer drug loading efficiency (52.6% for doxorubicin hydrochloride, DOX·HCl). Moreover, the DOX-loaded vesicles exhibited excellent antitumor activity (2-fold better than free DOX). This "chelating-just-inside" strategy for synthesizing asymmetrical polymer vesicles demonstrated promising potential theranostic applications in magnetic resonance imaging and cancer-targeted drug delivery.

Presented in this article is the synthesis of a new class of block copolymer, poly(ethylene oxide)-blockpoly(tert-butyl acrylate-stat-acrylic acid) [PEO-b-P(AA-stat-tBA)], which can self-assemble into polymer vesicles with tuneable sizes at various conditions. The biocompatible and hydrophilic PEO chains form the vesicle coronas, while the PAA-stat-PtBA chains form the membrane. Superparamagnetic iron oxide nanoparticles (SPIONs) were generated in situ within the membrane of the polymer vesicles by nanoprecipitation. 1 H NMR, GPC, DLS, TGA, VSM and TEM were employed to characterize the structure and properties of the block copolymer, polymer vesicles and Fe 3 O 4 -decorated magnetic polymer vesicles. The water-dispersible, biocompatible, drug deliverable and superparamagnetic polymer vesicles exhibited excellent colloidal stability at a range of pH conditions and very high T 2 relaxivity, demonstrating ultra-sensitivity for magnetic resonance imaging and promising potential applications in nanomedicine.

The AIE chiral polytriazole has the capacity to self-assemble into diverse fluorescent nano/micro architectures at different water contents and polymer concentrations.