Utilizing CO2 as one of the monomer resource, poly(vinylcyclohexene carbonates) (PVCHCs) are used as the precursor for preparing cationic PVCHCs (CPVCHCs) via thiol-ene click functionalization. Through the functionalization, CPVCHC-43 with a tertiary amine density of 43% relative to the backbone is able to display a significantly antibacterial ability against Staphylococcus aureus (S. aureus). Blending CPVCHC-43 with polyacrylonitrile (PAN), CPVCHC/PAN nanofiber meshes (NFMs) have been successfully prepared by electrospinning. More importantly, two crucial fibrous structural factors including CPVCHC/PAN weight ratio and fiber diameter have been systematically investigated for the effects on the antibacterial performance of the NFMs. Sequentially, a quaternization treatment has been employed on the NFMs with an optimal fibrous structure to enhance the antibacterial ability. The resulting quaternized NFMs have demonstrated the great biocidal effects against Gram-positive and Gram-negative bacteria. Moreover, the excellent biocompatibility of the quaternized NFMs have also been thoroughly evaluated and verified. This article is protected by copyright. All rights reserved.

Preparation of CO2 -based Cationic Polycarbonate/Polyacrylonitrile Nanofibers with an Optimal Fibrous Microstructure for Antibacterial Applications.

The development of new techniques to rapidly and accurately detect bacteria has drawn continuous attention due to the potential threats posed by bacteria to human health and safety. Recently, a novel strategy based on fluorescent probes has drawn considerable interest for the detection of bacteria due to its high selectivity, fast response, and simple operation. In this review, we summarize the recent progress on fluorescent probes for the specific recognition and discrimination of Gram-negative and Gram-positive bacteria. In particular, we outline current design strategies, such as targeting of the differences in surface components, cell wall components, endogenous enzymes, surface charge, and hydrophobicity of various kinds of bacteria to develop various fluorescent sensors (organic small-molecule fluorescent probes, nanoprobes, and metal ion probes). We also emphasize the application of organic molecules in probe recognition elements. We hope that this review can stimulate this research area in bacterial detection and imaging in the future.

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Recent Progress in Identifying Bacteria with Fluorescent Probes

Enhancing the interactions between photosensitizers and bacteria is key to developing effective photodynamic antibacterial agents. However, the influence of different structures on the therapeutic effects has not been systematically investigated. Herein, 4 BODIPYs with distinct functional groups, including the phenylboronic acid (PBA) group and pyridine (Py) cations, were designed to explore their photodynamic antibacterial activities. The BODIPY with the PBA group (IBDPPe-PBA) exhibits potent activity against planktonic Staphylococcus aureus (S. aureus) upon illumination, while the BODIPY with Py cations (IBDPPy-Ph) or both the PBA group and Py cations (IBDPPy-PBA) can significantly minimize the growth of both S. aureus and Escherichia coli (E. coli). In particular, IBDPPy-Ph can not only eliminate the mature S. aureus biofilm and E. coli biofilm in vitro, but also promote the healing of the infected wound. Our work provides an alternative for reasonable design of photodynamic antibacterial materials.

Structural optimization of BODIPY photosensitizers for enhanced photodynamic antibacterial activities.

Recent advancements in aggregation-induced emission (AIE) macromolecular materials have brought their attention as potential antibacterial solutions, these materials offer new approaches to cure multidrug-resistant infections and biofilms in bacterial infections as well as real-time monitoring and specific targeting of bacteria. This review provides an overview of the three main categories of AIE macromolecular materials with antibacterial properties; namely AIE-active polymers, AIEgen@polymer complexes, and CTE-based polymers. The mechanisms and applications of these materials in antibacterial treatment, wound care, and protective equipment are also discussed. The potential for future developments and application directions of AIE-based antimicrobial materials are finally highlighted. This article is protected by copyright. All rights reserved.

AIE Macromolecular Materials for Antibacterial Applications.

Owing to the outstanding photophysical properties, organic luminescent materials featuring aggregation-induced emission (AIE) characteristics have attracted wide attention in various fields. Numerous researches focused on low-mass AIE luminogens, and relatively less attention has been paid on AIE polymers and the related applications, in spite of the fact that AIE polymers exhibit excellent advantages of processability, multifunctional integration and synergistic effects. In this review, we briefly summarize and discuss the superiorities of AIE polymers in preparation, properties and bio-applications, and the considerable progress in these aspects are introduced as well. Finally, the structure-property relationship, challenges and opportunities are also discussed. Hopefully, this review will be a trigger for smart AIE polymer research and further broaden their applications. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/smo.20220008

Smart aggregation‐induced emission polymers: Preparation, properties and bio‐applications

Combining rapid microbial discrimination with antibacterial properties, multi-functional biomacromolecules allow the timely diagnosis and effective treatment of infectious diseases. Through a two-step approach involving organocatalytic ring-opening copolymerization and thiol-ene modification, aggregation-induced emission (AIE) polycarbonates decorated with tertiary amines were prepared. After being ionized using acetic acid, the obtained cationic AIE polycarbonate with excellent water solubility showed bacteria imaging capabilities and antibacterial activities toward both Gram-positive S. aureus and Gram-negative E. coli. It was indicated via scanning electron microscope images that the bactericidal mechanism involved membrane lysis, consistent with most cationic polymers. Through further co-grafting carboxyl and tertiary amine groups, mixed-charge AIE polycarbonates were obtained. The isoelectric points of such mixed-charge AIE polycarbonates could be simply tuned based on the grafting ratio of positive and negative moieties. Compared with the cationic AIE polycarbonate, mixed-charge AIE polycarbonates allowed the rapid and selective imaging of S. aureus, but not E. coli. The selectivity probably arose from the lower binding forces between the mixed-charge AIE polycarbonates and the low-negative-charge components of the E. coli surface. Therefore, these biodegradable polycarbonates, which integrated selective bacteria imaging and antibiotic abilities, potentially suggest a precision medicine approach for infectious diseases. The overall synthesis approach and mixed-charge AIE polycarbonates provide new references for the design and application of bio-related AIE polymers.

Zhimin Lu

Papers

Antibacterial AIE polycarbonates endowed with selective imaging capabilities by adjusting the electrostaticity of the mixed-charge backbone