Biodegradable Antibacterial Polymeric Nanosystems: A New Hope to Cope with Multidrug-Resistant Bacteria

Functionalized aliphatic polyketones with germicide activity

Surfaces coated by polyketones bearing quaternary ammonium compounds showed excellent bactericidal properties with antibacterial rate of 99%.

Optical clearing of tissues: Issues of antimicrobial phototherapy and drug delivery

This review presents principles and novelties in the field of tissue optical clearing (TOC) technology, as well as application for optical monitoring of drug delivery and effective antimicrobial phototherapy. TOC is based on altering the optical properties of tissue through the introduction of immersion optical cleaning agents (OCA), which impregnate the tissue of interest. We also analyze various methods and kinetics of delivery of photodynamic agents, nanoantibiotics and their mixtures with OCAs into the tissue depth in the context of antimicrobial and antifungal phototherapy. In vitro and in vivo studies of antimicrobial phototherapies, such as photodynamic, photothermal plasmonic and photocatalytic, are summarized, and the prospects of a new TOC technology for effective killing of pathogens are discussed.

A Self-defense Hierarchical Antibacterial Surface with Inherent Antifouling and Bacteria-activated Bactericidal Properties for Infection Resistance

Biomedical device-associated infection (BAI) is one of the main reasons for the function failure of implants in clinic practices. Development of high-efficiency antibacterial materials is of great significance to reduce...

All-in-One: Multifunctional Hydrogel Accelerates Oxidative Diabetic Wound Healing through Timed-Release of Exosome and Fibroblast Growth Factor

The treatment of diabetic wounds remains a major challenge in clinical practice, with chronic wounds characterized by multiple drug-resistant bacterial infections, angiopathy, and oxidative damage to the microenvironment. Herein, a novel in situ injectable HA@MnO₂ /FGF-2/Exos hydrogel is introduced for improving diabetic wound healing. Through a simple local injection, this hydrogel is able to form a protective barrier covering the wound, providing rapid hemostasis and long-term antibacterial protection. The MnO₂ /ε-PL nanosheet is able to catalyze the excess H₂ O₂ produced in the wound, converting it to O₂ , thus not only eliminating the harmful effects of H₂ O₂ but also providing O₂ for wound healing. Moreover, the release of M2-derived Exosomes (M2 Exos) and FGF-2 growth factor stimulates angiogenesis and epithelization, respectively. These in vivo and in vitro results demonstrate accelerated healing of diabetic wounds with the use of the HA@MnO₂ /FGF-2/Exos hydrogel, presenting a viable strategy for chronic diabetic wound repair.

Superfast and Water-Insensitive Polymerization on α-Amino Acid N-Carboxyanhydrides to Prepare Polypeptides Using Tetraalkylammonium Carboxylate as the Initiator

We design the tetraalkylammonium carboxylate-initiated superfast polymerization on α-amino acid N-carboxyanhydrides (NCA) for efficient synthesis of polypeptides. Carboxylates, as a new class of initiator for NCA polymerization, can initiate the superfast NCA polymerization without the need of extra catalysts and the polymerization can be operated in open vessels at ambient condition without the use of glove box. Tetraalkylammonium carboxylate-initiated polymerization on NCA easily affords block copolymers with at least 15 blocks. Moreover, this method avoids tedious purification steps and enables direct polymerization on crude NCAs in aqueous environments to prepare polypeptides and one-pot synthesis of polypeptide nanoparticles. These advantages and the mild polymerization condition of tetraalkylammonium carboxylate-initiated NCA polymerization imply its great potential in functional exploration and application of polypeptides.

Antibacterial Polymers Based on Poly(2-hydroxyethyl methacrylate) and Thiazolium Groups with Hydrolytically Labile Linkages Leading to Inactive and Low Cytotoxic Compounds

Herein, we develop a well-defined antibacterial polymer based on poly(2-hydroxyethyl methacrylate) (PHEMA) and a derivative of vitamin B1, easily degradable into inactive and biocompatible compounds. Hence, thiazole moiety was attached to HEMA monomer through a carbonate pH-sensitive linkage and the resulting monomer was polymerized via reversible addition-fragmentation chain transfer (RAFT) polymerization. N-alkylation reaction of the thiazole groups leads to cationic polymer with thiazolium groups. This polymer exhibits excellent antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) with an MIC value of 78 µg mL-1, whereas its degradation product, thiazolium small molecule, was found to be inactive. Hemotoxicity studies confirm the negligible cytotoxicity of the degradation product in comparison with the original antibacterial polymer. The degradation of the polymer at physiological pH was found to be progressive and slow, thus the cationic polymer is expected to maintain its antibacterial characteristics at physiological conditions for a relative long period of time before its degradation. This degradation minimizes antimicrobial pollution in the environment and side effects in the body after eradicating bacterial infection.

Nanomedicine to advance the treatment of bacteria-induced acute lung injury

Bacteria-induced acute lung injury (ALI) is associated with a high mortality rate due to the lack of an effective treatment. Patients often rely on supportive care such as low tidal volume ventilation to alleviate the symptoms. Nanomedicine has recently received much attention owing to its premium benefits of delivering drugs in a sustainable and controllable manner while minimizing the potential side effects. It can effectively improve the prognosis of bacteria-induced ALI through targeted delivery of drugs, regulation of multiple inflammatory pathways, and combating antibiotic resistance. Hence, in this review, we first discuss the pathogenesis of ALI and its potential therapeutics. In particular, the state-of-the-art nanomedicines for the treatment of bacteria-induced ALI are highlighted, including their administration routes, in vivo distribution, and clearance. Furthermore, the available bacteria-induced ALI animal models are also summarized. In the end, future perspectives of nanomedicine for ALI treatment are proposed.

Facile Homobifunctional Imidoester Modification of Advanced Nanomaterials for Enhanced Antibiotic Synergistic Effect

Resistance to antibiotics because of misuse and overuse is one of the greatest public health challenges worldwide. Despite the introduction of advanced nanotechnology in the production of antibiotics, the choice of appropriate medicines is limited due to side effects such as blood coagulation, toxicity, low efficacy, and low biocompatibility; therefore, novel nanomaterial composites are required to counter these repercussions. We first introduce a facile method for synthesizing a homobifunctional imidoester-coated nanospindle (HINS) zinc oxide composite for enhancement of antibiotic efficacy and reduction of toxicity and blood coagulation. The antibiotic efficacy of the composites is twice that of commercialized zinc nanoparticles; in addition, they have good biocompatibility, have increased surface charge and solubility owing to the covalent acylation groups of HI, and produce a large number of Zn⁺ ions and defensive reactive oxygen species (ROS) that effectively kill bacteria and fungi. The synergistic effect of a combination therapy with the HINS composite and itraconazole shows more than 90% destruction of fungi in treatments with low dosage with no cytotoxicity or coagulation evident in intravenous administration in in vitro and in vivo experiments. Thus, HINS composites are useful in reducing the effect of misuse and overuse of antibiotics in the medical field.

Stimuli-responsive nanocarriers for bacterial biofilm treatment

ABSTRACT

Bacterial biofilm infections have been threatening the human's life and health globally for a long time because they typically cause chronic and persistent infections. Traditional antibiotic therapies can hardly eradicate biofilms in many cases, as biofilms always form a robust fortress for pathogens inside, inhibiting the penetration of drugs. To address the issues, many novel drug carriers emerged as promising strategies for biofilm treatment. Among them, stimuli-responsive nanocarriers have attracted much attentions for their intriguing physicochemical properties, such as tunable size, shape and surface chemistry, especially smart drug release characteristic. Based on the microenvironmental difference between biofilm infection sites and normal tissue, many stimuli, such as bacterial products accumulating in biofilms (enzymes, glutathione, etc.), lower pH and higher H₂O₂ levels, have been employed and proved in favor of "on-demand" drug release for biofilm elimination. Additionally, external stimuli including light, heat, microwave and magnetic fields are also able to control the drug releasing behavior artificially. In this review, we summarized recent advances in stimuli-responsive nanocarriers for combating biofilm infections, and mainly, focusing on the different stimuli that trigger the drug release.

摘要

, , 。 , , 。 , , 。 , -, , , , 。 , , (, ), pHH₂O₂, ""。 , , , , 。 , , 。.

Hyaluronidase-responsive phototheranostic nanoagents for fluorescence imaging and photothermal/photodynamic therapy of methicillin-resistant Staphylococcus aureus infections

Infectious diseases associated with antibiotic-resistant bacteria are ever-growing threats to public health. Effective treatment and detection methods of bacterial infections are in urgent demand. Herein, novel phototheranostic nanoagents (MoS2@HA-Ce6 nanosheets, MHC NSs) with hyaluronidase (HAase)-responsive fluorescence imaging (FLI) and photothermal/photodynamic therapy (PTT/PDT) functions were prepared. In this design, Ce6 is used as both a photosensitizer and a fluorescent probe, while MoS2 nanosheets (MoS2 NSs) serve as both a fluorescence quencher and a photothermal agent. Hyaluronic acid conjugated with Ce6 (HA-Ce6) was assembled on the surface of MoS2 NSs to form MHC NSs. Without the HAase secreted by methicillin-resistant Staphylococcus aureus (MRSA), the fluorescence of Ce6 is quenched by MoS2 NSs, while in the presence of MRSA, HAase can degrade the HA and release Ce6, which restores the fluorescence and photodynamic activity of Ce6. The experimental results show that MHC NSs can fluorescently image the MRSA both in vitro and in vivo by HAase activation. Meanwhile, MHC NSs can serve as PTT/PDT dual-mode antibacterial agents for MRSA. In vitro antibacterial results show that MHC NSs can kill 99.97% MRSA under 635 nm and 785 nm laser irradiation. In vivo study further shows that MHC NSs can kill 99.9% of the bacteria in MRSA infected tissues in mice and prompt wound healing by combined PTT/PDT. This work provides novel HAase-responsive phototheranostic nanoagents for effective detection and treatment of bacterial infections.

A green electrolysis of silver-decorated MoS2 nanocomposite with an enhanced antibacterial effect and low cytotoxicity

To tackle the devastating microbial infections for the public health, a continuous search for effective and safe nanobiocides based on their prominent nanoscale effects has been extensively explored during past decades. In this study, a green electrolysis method was employed to synthesize silver-doped molybdenum sulfide (Ag@MoS₂) composite materials. The obtained nanocomposites exhibited a sheet-like structure with a large specific surface area, which contributed to the efficient loading and refined distribution of silver nanoparticles. G^- E. coli and G ⁺ S. aureus were used as model bacteria for the antibacterial test, which revealed enhanced antibacterial activity of produced nanocomposites with an identified destructive effect on preformed biofilms. It was found that within 72 hour incubation, 20 μg mL^-1 Ag@MoS₂ was sufficient to inhibit the growth of E. coli and S. aureus without visible colony formation, pointing to a desirable long-term antibacterial activity. Further a mechanistic antibiosis study of Ag@MoS₂ indicated the involvement of a generation of reactive oxygen species. Notably, owing to the well-distributed silver nanoparticles on the nontoxic MoS₂ nanosheet, the cytotoxicity evaluation results revealed that produced nanocomposites exhibited negligible toxicity to mammalian cells, and thereby held promising potential for biomedical applications.

Facile antibacterial materials with turbine-like structure for P. aeruginosa infected scald wound healing

Pseudomonas aeruginosa (P. aeruginosa) is a popular hospital pathogen and the major cause of morbidity and mortality in patients with cystic fibrosis (CF) and impaired immune system. Herein, we designed and synthesized a series of organic molecules MTEBT-n (n = 1, 2, 3) to specifically and effectively kill P. aeruginosa. Hydrophobic triphenylamine was selected as the skeleton, and hydrophilic primary ammonium salts that can easily penetrate the cell walls of Gram-negative bacteria and accumulate in the bacteria were used to adjust the hydrophilic-hydrophobic ratio of the molecules, resulting in different antibacterial activity. As the hydrophilic-hydrophobic ratio increased in the structures from MTEBT-1 to MTEBT-3, the antibacterial activity of the three molecules were gradually enhanced with killing effects of 25%, 75% and 95% against P. aeruginosa, respectively. The antibacterial mechanisms of MTEBT-n were demonstrated to destroy the bacterial membrane, which could effectively prevent the development of drug resistance. In addition, MTEBT-3 with the highest antibacterial activity could inhibit P. aeruginosa biofilm very well, and heal the P. aeruginosa infected scald wounds. This work provides a potential organic antimicrobial material for clinical antimicrobial therapy of P. aeruginosa infection, and offers a molecular engineering strategy for designing new antimicrobials.

Design of nanoengineered antibacterial polymers for biomedical applications

Pathogenic bacteria have become global threats to public health. Since the advent of antibiotics about 100 years ago, their use has been embraced with great enthusiasm because of their effective treatment of bacterial infections. However, the evolution of pathogenic bacteria with resistance to conventional antibiotics has resulted in an urgent need for the development of a new generation of antibiotics. The use of antimicrobial polymers offers the promise of enhancing the efficacy of antimicrobial agents. Of the various antibacterial polymers that effectively eradicate pathogenic bacteria, those that are nanoengineered have garnered significant research interest in their design and biomedical applications. Because of their high surface area and high reactivity, these polymers show greater antibacterial activity than conventional antibacterial agents, by inhibiting the growth or destroying the cell membrane of pathogenic bacteria. This review summarizes several strategies for designing nanoengineered antibacterial polymers, explores the factors that affect their antibacterial properties, and examines key features of their design. It then comments briefly on the future prospects for nanoengineered antibacterial polymers. This review thus provides a feasible guide to developing nanoengineered antibacterial polymers by presenting both broad and in-depth bench research, and it offers suggestions for their potential in biomedical applications.

Synthesis and self-assembly of curcumin-modified amphiphilic polymeric micelles with antibacterial activity

BACKGROUND

The ubiquitous nature of bacterial biofilms combined with the enhanced resistance towards antimicrobials has led to the development of an increasing number of strategies for biofilm eradication. Such strategies must take into account the existence of extracellular polymeric substances, which obstruct the diffusion of antibiofilm agents and assists in the maintenance of a well-defended microbial community. Within this context, nanoparticles have been studied for their drug delivery efficacy and easily customised surface. Nevertheless, there usually is a requirement for nanocarriers to be used in association with an antimicrobial agent; the intrinsically antimicrobial nanoparticles are most often made of metals or metal oxides, which is not ideal from ecological and biomedical perspectives. Based on this, the use of polymeric micelles as nanocarriers is appealing as they can be easily prepared using biodegradable organic materials.

RESULTS

In the present work, micelles comprised of poly(lactic-co-glycolic acid) and dextran are prepared and then functionalised with curcumin. The effect of the functionalisation in the micelle's physical properties was elucidated, and the antibacterial and antibiofilm activities were assessed for the prepared polymeric nanoparticles against Pseudomonas spp. cells and biofilms. It was found that the nanoparticles have good penetration into the biofilms, which resulted in enhanced antibacterial activity of the conjugated micelles when compared to free curcumin. Furthermore, the curcumin-functionalised micelles were efficient at disrupting mature biofilms and demonstrated antibacterial activity towards biofilm-embedded cells.

CONCLUSION

Curcumin-functionalised poly(lactic-co-glycolic acid)-dextran micelles are novel nanostructures with an intrinsic antibacterial activity tested against two Pseudomonas spp. strains that have the potential to be further exploited to deliver a secondary bioactive molecule within its core.

Recent Advances in Peptide Nucleic Acids as Antibacterial Agents

The emergence of antibiotic-resistant bacteria and the slow progress in searching for new antimicrobial agents makes it hard to treat bacterial infections and cause problems for the healthcare system worldwide, including high costs, prolonged hospitalizations, and increased mortality. Therefore, the discovery of effective antibacterial agents is of great importance. One attractive alternative is antisense peptide nucleic acid (PNA), which inhibits or eliminates gene expression by binding to the complementary messenger RNA (mRNA) sequence of essential genes or the accessible and functionally important regions of the ribosomal RNA (rRNA). Following 30 years of development, PNAs have played an extremely important role in the treatment of Gram-positive, Gram-negative, and acidfast bacteria due to their desirable stability of hybrid complex with target RNA, the strong affinity for target mRNA/rRNA, and the stability against nucleases. PNA-based antisense antibiotics can strongly inhibit the growth of pathogenic and antibiotic-resistant bacteria in a sequence-specific and dose-dependent manner at micromolar concentrations. However, several fundamental challenges, such as intracellular delivery, solubility, physiological stability, and clearance still need to be addressed before PNAs become broadly applicable in clinical settings. In this review, we summarize the recent advances in PNAs as antibacterial agents and the challenges that need to be overcome in the future.

Synthesis and antibacterial activity of polymer-antibiotic conjugates incorporated into a resin-based dental adhesive

This work reports on polymer-antibiotic conjugates (PACs) as additives to resin-based restorative dental materials as a new strategy to convey sustained antibacterial character to these materials. Such antibacterial performance is expected to improve their longevity in the oral cavity. Using the previously reported ciprofloxacin (Cip)-based PAC as a control, a penicillin V (PV)-based PAC was investigated. The monomer-antibiotic conjugate (MAC) containing a methacrylate monomer group and a PV moiety was prepared via nucleophilic substitution between 2-chloroethyl methacrylate (CEMA) and penicillin V potassium (PVK). The PV-based PAC was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization of the MAC with hydroxyethyl methacrylate (HEMA), and further characterized by 1H NMR and gel permeation chromatography (GPC) analysis. Antibiotic resistance was investigated by passaging bacteria in low concentrations of the antibiotic for 19 days, followed by a 48 h challenge at higher concentrations. Our results suggest that the development of antibiotic resistance is unlikely. Zone of inhibition (ZOI) assays revealed no clearing zones around PV-containing resins indicating minimal antibiotic leakage from the material. Similarly, MTT assay demonstrated that the antibiotic-containing specimens did not release cytotoxic byproducts that may inhibit human gingival fibroblast growth. Counting of colony-forming units in an S. mutans biofilm model was used to assess bacterial survival at baseline and after subjecting the antibiotic-containing resin specimens to an enzymatic challenge for 30 days. Significantly reduced bacterial counts were observed as the biofilm aged from 24 to 72 h, and salivary enzymatic exposure did not reduce the antibacterial efficacy of the discs, suggesting that PV-resin will be effective in reducing the re-incidence of dental caries.

Novel Strategy to Combat Antibiotic Resistance: A Sight into the Combination of CRISPR/Cas9 and Nanoparticles

Antibiotic resistance is a significant crisis that threatens human health and safety worldwide. There is an urgent need for new strategies to control multidrug-resistant (MDR) bacterial infections. The latest breakthrough in gene-editing tools based on CRISPR/Cas9 has potential application in combating MDR bacterial infections because of their high targeting ability to specifically disrupt the drug resistance genes that microbes use for infection or to kill the pathogen directly. Despite the potential that CRISPR/Cas9 showed, its further utilization has been hampered by undesirable delivery efficiency in vivo. Nanotechnology offers an alternative way to overcome the shortcomings of traditional delivery methods of therapeutic agents. Advances in nanotechnology can improve the efficacy and safety of CRISPR/Cas9 components by using customized nanoparticle delivery systems. The combination of CRISPR/Cas9 and nanotechnology has the potential to open new avenues in the therapy of MDR bacterial infections. This review describes the recent advances related to CRISPR/Cas9 and nanoparticles for antimicrobial therapy and gene delivery, including the improvement in the packaging and localizing efficiency of the CRISPR/Cas9 components in the NP (nanoparticle)/CRISPR system. We pay particular attention to the strengths and limitations of the nanotechnology-based CRISPR/Cas9 delivery system to fight nosocomial pathogens.We highlight the need for more scientific research to explore the combinatorial efficacy of various nanoparticles and CRISPR technology to control and prevent antimicrobial resistance.

Polymeric Nanoparticles for Antimicrobial Therapies: An Up-To-Date Overview

Despite the many advancements in the pharmaceutical and medical fields and the development of numerous antimicrobial drugs aimed to suppress and destroy pathogenic microorganisms, infectious diseases still represent a major health threat affecting millions of lives daily. In addition to the limitations of antimicrobial drugs associated with low transportation rate, water solubility, oral bioavailability and stability, inefficient drug targeting, considerable toxicity, and limited patient compliance, the major cause for their inefficiency is the antimicrobial resistance of microorganisms. In this context, the risk of a pre-antibiotic era is a real possibility. For this reason, the research focus has shifted toward the discovery and development of novel and alternative antimicrobial agents that could overcome the challenges associated with conventional drugs. Nanotechnology is a possible alternative, as there is significant evidence of the broad-spectrum antimicrobial activity of nanomaterials and nanoparticles in particular. Moreover, owing to their considerable advantages regarding their efficient cargo dissolving, entrapment, encapsulation, or surface attachment, the possibility of forming antimicrobial groups for specific targeting and destruction, biocompatibility and biodegradability, low toxicity, and synergistic therapy, polymeric nanoparticles have received considerable attention as potential antimicrobial drug delivery agents. In this context, the aim of this paper is to provide an up-to-date overview of the most recent studies investigating polymeric nanoparticles designed for antimicrobial therapies, describing both their targeting strategies and their effects.

Nickel-Catalyzed Amination of Aryl Chlorides with Amides

A nickel-catalyzed amination of aryl chlorides with diverse amides via C-N bond cleavage has been realized under mild conditions. A broad substrate scope with excellent functional group tolerance at a low catalyst loading makes the protocol powerful for synthesizing various aromatic amines. The aryl chlorides could selectively couple to the amino fragments rather than the carbonyl moieties of amides. Our protocol complements the conventional amination of aryl chlorides and expands the usage of inactive amides.

DNA pom-pom nanostructure as a multifunctional platform for pathogenic bacteria determination and inactivation

Pathogenic bacteria levels are significantly related with disease control, clinical diagnosis, and even environmental monitoring. It is becoming highly urgent to achieve ultrasensitive detection of pathogenic bacteria and efficient combat of bacterial infection. Toward this end, we have assembled a DNA Pom-Pom nanostructure (PP-N) based multifunctional platform for pathogenic bacteria determination and inactivation. In particular, one DNA oligonucleotide probe that serve as a trigger was specifically designed for the autonomous cross-opening of metastable DNA hairpin probes and long dsDNA structure formation, achieving a catalytic self-assembly of DNA nanostructure. Numerous DNA strands in this PP-N assembly provide sufficient interaction sites for functional domains and connector, showing high programmability, excellent biostability, as well as selective target recognition. With these properties, the fluorescence dyes modified PP-N platform showed excellent bacteria analysis with both excellent selectivity and ultrasensitive determination limit as low as 2.0 CFU/mL. Furthermore, the aptamer-functionalized and antibiotics loaded PP-N platform demonstrate excellent merits of high antibiotics-loading capacity and negligible cytotoxicity to targets. Therefore, this DNA PP-N assembly based multifunctional platform promise its great application in targeted sensing, combating bacterial infection, and potential clinic therapy.

Nanotheranostics: A Possible Solution for Drug-Resistant Staphylococcus aureus and their Biofilms?

Staphylococcus aureus is a notorious pathogen that colonizes implants (orthopedic and breast implants) and wounds with a vicious resistance to antibiotic therapy. Methicillin-resistant S. aureus (MRSA) is a catastrophe mainly restricted to hospitals and emerged to community reservoirs, acquiring resistance and forming biofilms. Treating biofilms is problematic except via implant removal or wound debridement. Nanoparticles (NPs) and nanofibers could combat superbugs and biofilms and rapidly diagnose MRSA. Nanotheranostics combine diagnostics and therapeutics into a single agent. This comprehensive review is interpretative, utilizing mainly recent literature (since 2016) besides the older remarkable studies sourced via Google Scholar and PubMed. We unravel the molecular S. aureus resistance and complex biofilm. The diagnostic properties and detailed antibacterial and antibiofilm NP mechanisms are elucidated in exciting stories. We highlight the challenges of bacterial infections nanotheranostics. Finally, we discuss the literature and provide "three action appraisals". (i) The first appraisal consists of preventive actions (two wings), avoiding unnecessary hospital visits, hand hygiene, and legislations against over-the-counter antibiotics as the general preventive wing. Our second recommended preventive wing includes preventing the adverse side effects of the NPs from resistance and toxicity by establishing standard testing procedures. These standard procedures should provide breakpoints of bacteria's susceptibility to NPs and a thorough toxicological examination of every single batch of synthesized NPs. (ii) The second appraisal includes theranostic actions, using nanotheranostics to diagnose and treat MRSA, such as what we call "multifunctional theranostic nanofibers. (iii) The third action appraisal consists of collaborative actions.

A pH/H2O2 dual triggered nanoplatform for enhanced photodynamic antibacterial efficiency

Bacterial infection and biofilms cause non-healing chronic wounds and threaten human health. Although antibiotics still play an irreplaceable role to treat infectious diseases in clinics, increasing attention has been paid to the problem of multidrug resistance (MDR). As a novel strategy to deal with bacterial infection, photodynamic antimicrobial therapy (PDAT) has shown promising potential to reduce bacterial infection, and stimuli-responsive nanomaterials have been shown to enhance the antibacterial efficiency and postpone the emergence of drug-resistant bacteria. In this work, we developed a bacterial microenvironment-responsive nanoplatform to eliminate bacteria and bacterial biofilms under 650 nm laser irradiation. Reversible addition-fragmentation chain transfer (RAFT) polymerization was applied to synthesize an H2O2 responsive block copolymer of POEGMA-b-PBMA, and the antibacterial drug of porphyrin TAPP was loaded to form nanoparticles (PT) by a co-assembled approach. At the infection area with overexpressed peroxide, nanoparticles were disintegrated due to the cleaved boronic ester leading to the release of TAPP. Furthermore, the released TAPP became protonated in the acidic infection area (pH = 5.5) and then enhanced its photodynamic antibacterial efficacy by producing higher singlet oxygen (1O2) levels under light irradiation. Both in vitro and in vivo antimicrobial and biofilm elimination experiments demonstrated that the responsive nanoplatform combined with PDAT has tremendous potential for the treatment of infections.

Smart nanomicelles with bacterial infection-responsive disassembly for selective antimicrobial applications

Electrostatic nanomicelles remain stable and biocompatible under physiological conditions, but readily burst and spill out cationic antimicrobial peptide to kill bacteria at infection sites.

Synthesis of cationic acrylate copolyvidone-iodine nanoparticles with double active centers and their antibacterial application

Antibacterial materials are rapidly emerging as a primary component in the mitigation of bacterial pathogens, and functional polymers play a vital role in the preparation of antibacterial coatings. In this study, a novel antibacterial polymer with double active centers was synthesized. Firstly, using one-pot soap-free emulsion polymerization technology, the cationic acrylate copolymeric polyvidone (CACPV) was synthesized by copolymerization of four monomers with different functions, which were methyl methacrylate (MMA), N-vinyl-2-pyrrolidone (NVP), γ-methacryloxypropyltrimethoxysilane (MAPTS) and [3-(methacryloylamino)propyl]trimethylammonium chloride (MAPTAC). Secondly, using iodine complexation, the cationic acrylate copolyvidone-iodine (CACPVI) nanoparticles were prepared. After being characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS) and contact angle test, the antibacterial activity of CACPVI was evaluated against the typical human pathogens Escherichia coli (E. coli, Gram-negative) and Staphylococcus aureus (S. aureus, Gram-positive). Additionally, CACPVI was used to improve the antibacterial activities of some materials, such as ink, dye and coatings. It was found that CACPVI presented an excellent antibacterial synergy. When the antibacterial activities were more than 99% at a concentration of 40.00 μg mL-1, CACPVI exhibited long-term antibacterial performance as expected. The antibacterial mechanism of this synergy was also investigated. In summary, a novel antibacterial polymer material with double active centers was successfully synthesized and was widely applied in coating, dye and ink materials for minimizing bacterial infection.

Phototherapy-based combination strategies for bacterial infection treatment

The development of nanomedicine is expected to provide an innovative direction for addressing challenges associated with multidrug-resistant (MDR) bacteria. In the past decades, although nanotechnology-based phototherapy has been developed for antimicrobial treatment since it rarely causes bacterial resistance, the clinical application of single-mode phototherapy has been limited due to poor tissue penetration of light sources. Therefore, combinatorial strategies are being developed. In this review, we first summarized the current phototherapy agents, which were classified into two functional categories: organic phototherapy agents (e.g., small molecule photosensitizers, small molecule photosensitizer-loaded nanoparticles and polymer-based photosensitizers) and inorganic phototherapy agents (e.g., carbo-based nanomaterials, metal-based nanomaterials, composite nanomaterials and quantum dots). Then the development of emerging phototherapy-based combinatorial strategies, including combination with chemotherapy, combination with chemodynamic therapy, combination with gas therapy, and multiple combination therapy, are presented and future directions are further discussed. The purpose of this review is to highlight the potential of phototherapy to deal with bacterial infections and to propose that the combination therapy strategy is an effective way to solve the challenges of single-mode phototherapy.

Supramolecular antibiotics: a strategy for conversion of broad-spectrum to narrow-spectrum antibiotics for Staphylococcus aureus

The propensity of broad-spectrum antibiotics to indiscriminately kill both pathogenic and beneficial bacteria has a profound impact on the spread of resistance across multiple bacterial species. Alternative approaches that narrow antibacterial specificity towards desired pathogenic bacterial population are of great interest. Here, we report an enzyme-responsive antibiotic-loaded nanoassembly strategy for narrow delivery of otherwise broad-spectrum antibiotics. We specifically target Staphylococcus aureus (S. aureus), an important blood pathogen that secretes PC1 β-lactamases. Our nanoassemblies selectively eradicate S. aureus grown in vitro with other bacteria, highlighting its potential capability in targeting the desired pathogenic bacterial population.

An enzyme-responsive and photoactivatable carbon-monoxide releasing molecule for bacterial infection theranostics

Infections caused by pathogenic bacteria, especially the drug-resistant bacteria, are posing a devastating threat to public health, which underscores the urgent needs for advanced strategies to effectively prevent and treat these intractable issues. Here we report a feasible and effective theranostic platform based on an enzyme-sensitive and photoactivatable carbon monoxide releasing molecule (CORM-Ac) for the successive detection and elimination of bacterial infection. The extracellular bacterial lipase can trigger the excited state intramolecular proton transfer (ESIPT) via elimination of the ester group in CORM-Ac, thus providing a fluorescence switch for an early warning of infection. Subsequently, the potent bactericidal therapy against the model bacterial strains, Staphylococcus aureus (S. aureus) and notorious methicillin-resistant Staphylococcus aureus (MRSA), was readily realized via photoinduced release of CO. In addition, the CORM-Ac and CORM showed good biocompatibility within a wide range of concentrations. The results of an infected animal wound test also demonstrated that the CORM-Ac-loaded gauze was effective in indicating the wound infection and accelerating the wound healing via the photoinduced CO release. The simplicity, functional integration, good biocompatibility and broad adaptability make CORM-Ac very attractive for bacterial theranostic applications.

Antibacterial Hybrid Hydrogels

Bacterial infectious diseases and bacterial-infected environments have been threatening the health of human beings all over the world. In view of the increased bacteria resistance caused by overuse or improper use of antibiotics, antibacterial biomaterials are developed as the substitutes for antibiotics in some cases. Among them, antibacterial hydrogels are attracting more and more attention due to easy preparation process and diversity of structures by changing their chemical cross-linkers via covalent bonds or noncovalent physical interactions, which can endow them with various specific functions such as high toughness and stretchability, injectability, self-healing, tissue adhesiveness and rapid hemostasis, easy loading and controlled drug release, superior biocompatibility and antioxidation as well as good conductivity. In this review, the recent progress of antibacterial hydrogel including the fabrication methodologies, interior structures, performances, antibacterial mechanisms, and applications of various antibacterial hydrogels is summarized. According to the bacteria-killing modes of hydrogels, several representative hydrogels such as silver nanoparticles-based hydrogel, photoresponsive hydrogel including photothermal and photocatalytic, self-bacteria-killing hydrogel such as inherent antibacterial peptides and cationic polymers, and antibiotics-loading hydrogel are focused on. Furthermore, current challenges of antibacterial hydrogels are discussed and future perspectives in this field are also proposed.

Self-targeting, zwitterionic micellar dispersants enhance antibiotic killing of infectious biofilms-An intravital imaging study in mice

Extracellular polymeric substances (EPS) hold infectious biofilms together and limit antimicrobial penetration and clinical infection control. Here, we present zwitterionic micelles as a previously unexplored, synthetic self-targeting dispersant. First, a pH-responsive poly(ε-caprolactone)-block-poly(quaternary-amino-ester) was synthesized and self-assembled with poly(ethylene glycol)-block-poly(ε-caprolactone) to form zwitterionic, mixed-shell polymeric micelles (ZW-MSPMs). In the acidic environment of staphylococcal biofilms, ZW-MSPMs became positively charged because of conversion of the zwitterionic poly(quaternary-amino-ester) to a cationic lactone ring. This allowed ZW-MSPMs to self-target, penetrate, and accumulate in staphylococcal biofilms in vitro. In vivo biofilm targeting by ZW-MSPMs was confirmed for staphylococcal biofilms grown underneath an implanted abdominal imaging window through direct imaging in living mice. ZW-MSPMs interacted strongly with important EPS components such as eDNA and protein to disperse biofilm and enhance ciprofloxacin efficacy toward remaining biofilm, both in vitro and in vivo. Zwitterionic micellar dispersants may aid infection control and enhance efficacy of existing antibiotics against remaining biofilm.

Nanoenzyme-Reinforced Injectable Hydrogel for Healing Diabetic Wounds Infected with Multidrug Resistant Bacteria

Diabetic wound healing remains a critical challenge due to its vulnerability to multidrug-resistant (MDR) bacterial infection, as well as the hyperglycemic and oxidative wound microenvironment. Herein, an injectable multifunctional hydrogel (FEMI) was developed to simultaneously overcome these hurdles. The FEMI hydrogel was fabricated through a Schiff-based reaction between ε-polylysine (EPL)-coated MnO₂ nanosheets (EM) and insulin-loaded self-assembled aldehyde Pluronic F127 (FCHO) micelles. Through a synergistic combination of EPL and "nanoknife-like" MnO₂ nanosheets, the FEMI hydrogel exhibited extraordinary antimicrobial capacities against MDR bacteria. The MnO₂ nanoenzyme reshaped the hostile oxidative wound microenvironment by decomposing the endogenous H₂O₂ into O₂. Meanwhile, the pH/redox dual-responsive FEMI hydrogel achieved a sustained and spatiotemporal controlled release of insulin to regulate the blood glucose. Our FEMI hydrogel demonstrated an accelerated MDR bacteria-infected diabetic wound healing in vivo and represents a versatile strategy for healing a broad range of tissue damages caused by diabetes.

Polymeric nanoencapsulation of alpha interferon increases drug bioavailability and induces a sustained antiviral response in vivo

Polymeric nanoparticulate systems allow the encapsulation of bio-active substances, giving them protection against external agents and increasing the drug's bioavailability. The use of biocompatible and biodegradable polymers usually guarantees the harmless character of the formulation, and a controlled drug release is also assured. A relatively easy procedure to obtain polymeric formulations of bioactive agents is ionotropic gelation, which allows the synthesis of chitosan (CS) - sodium tri-polyphosphate nanoparticles (NPs) loading encapsulated proteins. In this work, Bovine serum albumin (BSA) model protein and a recombinant porcine alpha interferon variant were used to obtain nanoparticulate formulations. The internalization of the encapsulated material by cells was studied using a BSA-fluorescein system; the fluorescent conjugate was observable inside the cells after 20 h of incubation. The therapeutic CS-alpha interferon formulation showed a maximum of protein released in vitro at around 90 h. This system was found to be safe in a cytotoxicity assay, while biological activity experiments in vitro showed antiviral protection of cells in the presence of encapsulated porcine alpha interferon. In vivo experiments in pigs revealed a significant and sustained antiviral response through overexpression of the antiviral markers OAS2 and PKR. This proves the preservation of porcine alpha interferon biological activity, and also that a lasting response was obtained. This procedure is an effective and safe method to formulate drugs in nanoparticulate systems, representing a significant contribution to the search for more effective drug delivery strategies.

Ultra-efficient Antibacterial System Based on Photodynamic Therapy and CO Gas Therapy for Synergistic Antibacterial and Ablation Biofilms

In recent years, with the emergence of various kinds of drug-resistant bacteria, existing antibiotics have become inefficient in killing these bacteria, and the formation of biofilms has further weakened the therapeutic effect. More problematically, the massive use and abuse of antibiotics have caused severe side effects. Thus, the development of ultra-efficient and safe antibacterial systems is urgently needed. Herein, a photodynamic therapy (PDT)-driven CO-controlled delivery system (Ce6&CO@FADP) is developed for synergistic antibacterial and ablation biofilms. Ce6&CO@FADP is constructed using a fluorinated amphiphilic dendritic peptide (FADP) and physically loaded with Ce6 and CORM-401. After efficiently entering the bacteria, Ce6&CO@FADP can rapidly release CO intracellularly by the massive consumption of the H₂O₂ generated during the PDT process, without affecting the generation of singlet oxygen (¹O₂). As such, the combination of CO and ¹O₂ exerts notable synergistic antibacterial and biofilm ablation effects both in vitro and in vivo (including subcutaneous bacterial infection and biofilm catheter models) experiments. More importantly, all biosafety assessments suggest the good biocompatibility of Ce6&CO@FADP. Together, these results reveal that Ce6&CO@FADP is an efficient and safe antibacterial system, which has essential application prospects for the treatment of bacterial infections and ablation of biofilms in vivo.

Organic Polymer Nanoparticles with Primary Ammonium Salt as Potent Antibacterial Nanomaterials

Bacterial infections induced by drug-resistant strains have become a global crisis. A membrane-disrupted mechanism is considered as an effective way to kill bacteria with little chance to trigger drug resistance. It is necessary to explore and develop new materials based on the membrane-disrupted mechanism to combat bacterial resistance. Here we report the design of organic nanoparticles based on a polymer (PDCP) as highly effective inhibition and bactericidal reagents. The PDCP is devised to have a hydrophobic skeleton and hydrophilic side chain modified with protonated primary amines, which could self-assemble to form organic nanoparticles (PDCP-NPs). By taking advantage of the large surface to volume ratio of nanoparticles, the synthesized PDCP-NPs have enriched positive charges and multiple membrane-binding sites. Research results display that PDCP-NPs have highly potent antibacterial activity in vitro and vivo, especially for Gram-negative bacteria with low toxicity against mammalian cells. This work design will inspire researchers to develop more membrane-disrupted bactericide and advance the applications of organic nanoparticles in the antibacterial area.

Synthetic macromolecules as therapeutics that overcome resistance in cancer and microbial infection

Synthetic macromolecular antimicrobials have shown efficacy in the treatment of multidrug resistant (MDR) pathogens. These synthetic macromolecules, inspired by Nature's antimicrobial peptides (AMPs), mitigate resistance by disrupting microbial cell membrane or targeting multiple intracellular proteins or genes. Unlike AMPs, these polymers are less prone to degradation by proteases and are easier to synthesize on a large scale. Recently, various studies have revealed that cancer cell membrane, like that of microbes, is negatively charged, and AMPs can be used as anticancer agents. Nevertheless, efforts in developing polymers as anticancer agents has remained limited. This review highlights the recent advancement in the development of synthetic biodegradable antimicrobial polymers (e.g. polycarbonates, polyesters and polypeptides) and anticancer macromolecules including peptides and polymers. Additionally, strategies to improve their in vivo bioavailability and selectivity towards bacteria and cancer cells are examined. Lastly, future perspectives, including use of artificial intelligence or machine learning, in the development of antimicrobial and anticancer macromolecules are discussed.

Nanomedicine Fight against Antibacterial Resistance: An Overview of the Recent Pharmaceutical Innovations

Based on the recent reports of World Health Organization, increased antibiotic resistance prevalence among bacteria represents the greatest challenge to human health. In addition, the poor solubility, stability, and side effects that lead to inefficiency of the current antibacterial therapy prompted the researchers to explore new innovative strategies to overcome such resilient microbes. Hence, novel antibiotic delivery systems are in high demand. Nanotechnology has attracted considerable interest due to their favored physicochemical properties, drug targeting efficiency, enhanced uptake, and biodistribution. The present review focuses on the recent applications of organic (liposomes, lipid-based nanoparticles, polymeric micelles, and polymeric nanoparticles), and inorganic (silver, silica, magnetic, zinc oxide (ZnO), cobalt, selenium, and cadmium) nanosystems in the domain of antibacterial delivery. We provide a concise description of the characteristics of each system that render it suitable as an antibacterial delivery agent. We also highlight the recent promising innovations used to overcome antibacterial resistance, including the use of lipid polymer nanoparticles, nonlamellar liquid crystalline nanoparticles, anti-microbial oligonucleotides, smart responsive materials, cationic peptides, and natural compounds. We further discuss the applications of antimicrobial photodynamic therapy, combination drug therapy, nano antibiotic strategy, and phage therapy, and their impact on evading antibacterial resistance. Finally, we report on the formulations that made their way towards clinical application.

Gradient Functionalization of Various Quaternized Polyethylenimines on Microfluidic Chips for the Rapid Appraisal of Antibacterial Potencies

The ability to appraise antibacterial potencies of surface-immobilized bactericidal polymers is still a major challenge in the engineering of antibacterial surfaces to combat hospital-acquired (nosocomial) infections. In this work, we fabricated a microfluidic platform with gradiently immobilized bactericidal polymers to enable the rapid appraisal of antibacterial potencies by in situ live/dead staining of bacteria. To this end, a variety of synthetic quaternary polymers, named QPEI-C₁, QPEI-C₆, QPEI-C₈, and QPEI-C₁₀, were gradiently immobilized in microfluidic channels, and their surface densities at different distances along the channels were quantified by using fluorescein-labeled polymers. We found that the surface densities of quaternary polymers could be well-tuned, and the length of the channel, resulting in a 50% reduction of live bacteria (L₅₀), can be used to appraise the antibacterial potency of each bactericidal polymer. For instance, the L₅₀ values of QPEI-C₆-, QPEI-C₈-, and QPEI-C₁₀-modified channels against Escherichia coli were 35.5, 44.7, and 49.2 mm, respectively, indicating that QPEI-C₁₀ exerted the most potent antibacterial efficacy. More importantly, this microfluidic platform enabled the rapid discrimination of antibacterial potencies of polymers (e.g., QPEI-C₈, and QPEI-C₁₀) while the conventional live/dead staining method found no significant difference. This work provides a powerful toolkit by combining advances of microfluidic systems and polymer science for the rapid screening of antibacterial coatings, which would find applications in surface modification of medical devices to combat bacterial infections.

The synergistic effect of hierarchical structure and alkyl chain length on the antifouling and bactericidal properties of cationic/zwitterionic block polymer brushes

A well-organized hierarchical structure and appropriate alkyl chain length facilitate the synergistic anti-biofilm effect.

Low-toxicity carbon quantum dots derived from gentamicin sulfate to combat antibiotic resistance and eradicate mature biofilms

Carbon quantum dots derived from gentamicin sulfate show low drug resistance, eradication of mature Staphylococcus aureus biofilm and low toxicity to mammalian cells.

A novel nanoparticle loaded with methyl caffeate and caffeic acid phenethyl ester against Ralstonia solanacearum—a plant pathogenic bacteria

Developing a novel agent and understanding the interaction model between multipolymer nanoparticles and bacteria could be worthwhile to induce the protection of crops with the prevalence of frequent hazards because of the use of pesticides and chemical resistance. Unlike metal nanoparticles, multipolymer nanoparticles have bacteriostatic properties against Ralstonia solanacearum that can trigger bacterial wilt by infecting the plant. Therefore, a novel poly(lactic-co-glycolic acid) nanoparticle containing caffeic acid phenethyl ester (CAPE) and methyl caffeate (MC) was prepared with the sustained-release property (for 10 d at pH 6.5); here, 50% of the cumulative release rate was achieved. It was observed that the cytomembrane of R. solanacearum was jeopardized by the nanoparticle by the creation of large holes on the bacterial surface. The nanoparticle has an approximate EC₅₀ value of 0.285 mg mL⁻¹ with active pharmaceutical ingredients (APIs), while the drug dosage could be reduced by 2/3. Furthermore, to reveal the possible mechanism of interaction between the multipolymer nanoparticles and bacteria, a formidable inhibition effect was observed; the pathogenicity-related genes, namely, phcA, phcB, pehC, egl, pilT, and polA, of R. solanacearum were downregulated by 1/2, 1/42, 1/13, 1/6, 1/2, and 1/8, respectively, showing significant effects on the major virulence-related genes. Hence, a novel nanoparticle with excellent antibacterial and sustained-release properties has been prepared, possessing the potential to replace chemical pesticides and serve as a new control strategy for mulberry blight disease.

Developing a novel agent and understanding an interaction model between multipolymer nanoparticles and bacteria could be worthwhile to induce the protection of crops with the prevalence of frequent hazards because of the use of chemical pesticides.

Plug-In Safe-by-Design Nanoinorganic Antibacterials

Due to antimicrobial resistance and the adverse health effects that follow broad and inappropriate use of antibacterial agents, new classes of antibacterials with broad and strong bactericidal activity and safety for human use are urgently required globally, increasingly so with the onset of climate change. However, R&D in this field is known to be rarely profitable, unless a cost-effective, flexible, and convenient platform that ensures the production of workable candidate antibacterials can be developed. To address this issue, inorganic nanomaterials have been considered for their bactericidal activities, yet further investigations of composition crystalline modifications and/or surface biomaterial coatings are still required to provide effective and safe antibacterial nanoparticles. In this study, we developed a plug-in system comprising a spark plasma reactor and a flow heater under nitrogen gas flow to supply precursor inorganic nanoparticles (Cu-Te configuration) that can be modulated in-flight at different temperatures. From antibacterial and toxicological assays in both in vitro and in vivo models, bactericidal and toxicological profiles showed that the plug-in system-based platform can be used to identify key parameters for producing safe-by-design agents with antibacterial activity [>88% (in vitro) and >80% (in vivo) in antibacterial efficiency] and safety (>65% in in vitro viability and >60% in in vivo survival rate).