An injectable hydrogel wound dressing based on an oxidized dextran and ε-poly-l-lysine network has multiple biological activities.

Bacterial resistance caused by the overuse of antibiotics and the shelter of biofilms has evolved into a global health crisis, which drives researchers to continuously explore antimicrobial molecules and strategies to fight against drug-resistant bacteria and biofilm-associated infections. Cationic antimicrobial peptides (AMPs) are considered to be a category of potential alternative for antibiotics owing to their excellent bactericidal potency and lesser likelihood of inducing drug resistance through their distinctive antimicrobial mechanisms. In this review, the hitherto reported plentiful action modes of AMPs are systematically classified into 15 types and three categories (membrane destructive, nondestructive membrane disturbance, and intracellular targeting mechanisms). Besides natural AMPs, cationic polypeptides, synthetic polymers, and biopolymers enable to achieve tunable antimicrobial properties by optimizing their structures. Subsequently, the applications of these cationic antimicrobial agents at the biointerface as contact-active surface coatings and multifunctional wound dressings are also emphasized here. At last, we provide our perspectives on the development of clinically significant cationic antimicrobials and related challenges in the translation of these materials.

Despite the excellent antimicrobial activity, the high toxicity and low selectivity of cationic antimicrobial peptides (AMPs) and their synthetic analogues impede their biomedical applications. In this study, we report a series of cationic peptidopolysaccharides synthesized by thiol−ene click chemistry of grafting antimicrobial polypeptides, methacrylate-ended poly(lysine-random-phenylalanine) (Me-K n F m ), onto a thiolated polysaccharide (dextran, Dex) backbone. Their copolymers (Dex-g-K n F m ) exhibit potent broad-spectrum antibacterial and antifungal activity against Gram-negative bacteria (Pseudomonas aeruginosa and Escherichia coli), Gram-positive bacteria [methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis], and fungi (Candida albicans) with minimal inhibitory concentrations in the range of 31.25−500 μg•mL −1 . More importantly, Dex-g-K n F m copolymers did not induce drug resistance of MRSA up to 17 passages. In addition, these copolymers have an improved hemocompatibility and exhibit good in vitro biocompatibility with murine myoblast (C2C12) cells. Among the synthesized peptidopolysaccharides, Dex L -g-K 12.5 F 12.5 -50%, as the optimal agent, displayed a selectivity more than 200 times the maximum value of polypeptide molecules. Furthermore, a strong in vivo antimicrobial efficacy with a log reduction above 3 in a mouse bacterial sepsis model has been obtained. These excellent biological properties present a promising prospect for Dexg-K n F m in biomedical applications.

treatments. [2] Especially, compared with conventional chemotherapy, PDT acts its biocidal activity mainly through the oxidative damage of biological macromolecules such as phospholipids, enzymes, proteins, and DNA in pathological tissue/cells, and therefore is difficult to induce drug resistance. [3] The drastic emergence of antibiotic resistance has evolved into a worldwide health crisis, and PDT is considered as a promising technology to combat drugresistant bacteria. [4] Although it shows strong curative antibacterial effect, PDT usually needs to be driven by external physical light, which makes it available in special environment or assisted by bulky equipment. [5] Therefore, the development of more convenient, universal, and manipulatable driving PDT strategies is highly desired.Recently, several attempts have been made to use in situ self-luminescence, such as bioluminescence, electrochemiluminescence (ECL), and chemiluminescence (CL), as excitation light source for driving PDT. [6] For example, a bioluminescent luciferase conjugated quantum dot was prepared, which could emit light and excite commercial photosensitizer micelles (Foscan) while interacting with coelenterazine, and successfully generated ROS and killed ≈50% lung cancer cells. [7] In 2018, Wang et al. exploited an electric-driven device to emit ECL by electrochemical reaction of luminescent agent (luminol) and H 2 O 2 , which further excited their synthesized polythiophene photosensitizer to produce ROS, and achieved 67-79% sterilization of bacteria and yeast. [8] More recently, Fan and co-workers also prepared a penetration-independent nano-photosensitizer Photodynamic therapy (PDT) has attracted wide attention in antibacterial applications due to its advantages of spatial-temporal selectivity, noninvasiveness, and low incidence to develop drug resistance. To make it more convenient, universal, and manipulatable for clinical application, a conceptually antibacterial strategy, namely "electroluminodynamic therapy" (ELDT), is presented by nanoassembly of an electroluminescent (EL) material and a photosensitizer, which is capable of generating reactive oxygen species (ROS) in situ under an electric field, i.e., the fluorescence emitted by the EL molecules excites the photosensitizer to generate singlet oxygen ( 1 O 2 ), for the oxidative damage of pathogens. Based on the scheme of ELDT, a flexible therapeutic device is fabricated through a hydrogel loading with ELDT nanoagents, followed by integration with a flexible battery, satisfying the requirements of being light and wearable for wound dressings. The ELDT-based flexible device presents potent ROS-induced killing efficacies against drug-resistant bacteria (>99.9%), so as to effectively inhibit the superficial infection and promote the wound healing. This research reveals a proof-of-concept ELDT strategy as a prospective alternative to PDT, which avoids the utilization of a physical light source, and achieves convenient and effective killing of drug-resistant bacteria through a hydrogel-ba...

An antibacterial and self-healing coating was fabricated via LbL assembly based on N-decyl PEI (DPEI) micelles.

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As the development of new antibiotics lags far behind the emergence of drug-resistant bacteria, alternative strategies to resolve this dilemma are urgently required. Antibody-drug conjugate is a promising therapeutic platform to delivering cytotoxic payloads precisely to target cells for efficient disease treatment. Antibody-antimicrobial conjugates (AACs) have recently attracted considerable interest from researchers as they can target bacteria in the target sites and improve the effectiveness of drugs (i.e., reduced drug dosage and adverse effects), abating the upsurge of antimicrobial resistance. In this review, the selection and progress of three essential blocks that compose the AACs: antibodies, antimicrobial payloads, and linkers are discussed. The commonly used conjugation strategies and the latest applications of AACs in recent years are also summarized. The challenges and opportunities of this booming technology are also discussed at the end of this review.