In Situ Preparation of Chlorine-Regenerable Antimicrobial Polymer Molecular Sieve Membranes

Microbial contamination has profoundly impacted human health, and the effective eradication of widespread microbial issues is essential for addressing serious hygiene concerns. Taking polystyrene (PS) membrane as an example, we herein developed report a robust strategy for the in situ preparation of chlorine-regenerable antimicrobial polymer molecular sieve membranes through combining post-crosslinking and nucleophilic substitution reaction. The cross-linking PS membranes underwent a reaction with 5,5-dimethylhydantoin (DMH), leading to the formation of polymeric N-halamine precursors (PS-DMH). These hydantoinyl groups within PS-DMH were then efficiently converted into biocidal N-halamine structures (PS-DMH-Cl) via a simple chlorination process. ATR-FTIR and XPS spectra were recorded to confirm the chemical composition of the as-prepared PS-DMH-Cl membranes. SEM analyses revealed that the chlorinated PS-DMH-Cl membranes displayed a rough surface with a multitude of humps. The effect of chlorination temperature and time on the oxidative chlorine content in the PS-DMH-Cl membranes was systematically studied. The antimicrobial assays demonstrated that the PS-DMH-Cl membranes could achieve a 6-log inactivation of E. coli and S. aureus within just 4 min of contact time. Additionally, the resulting PS-DMH-Cl membranes exhibited excellent stability and regenerability of the oxidative chlorine content.

Quaternary ammonium salts for water treatment with balanced rate of sterilization and degradation

The growing number of infections caused by drug-resistant bacteria which arise from the overuse of antibiotics has severely affected the normal operation of human society. The high antibacterial activity of QAS makes it promising as an alternative to antibiotics, but it suffers from secondary pollution due to its non-degradation. Here we have synthesized a class of gemini quaternary ammonium salts (GQAS) with different carbon chain lengths containing ester groups by using facile methylation reaction. Quaternary ammonium groups contribute to insert negatively charged bacterial membranes, resulting in membrane damage and bacteria death. Compared with conventional single-chain QAS, except for the more efficient antibacterial efficiency attribute to the presence of the second carbon chain, GQAS with alterable antibacterial properties can minimize the possibility of bacterial resistance and reduce the accumulation of GQAS in the environment through the introduction of degradable ester groups. GQAS is completely superior to the commercial bactericide benzalkonium chloride (BAC) in both antibacterial activity and degrade performance, which can be used as a more environmentally friendly bactericide.

Antibacterial Mesoporous Silica Granules Containing a Stable N-Halamine Moiety

High-efficacy and regenerable antimicrobial silica granules were prepared via oxa-Michael addition between poly(vinyl alcohol) (PVA) and methylene-bis-acrylamide (MBA) under the catalysis of sodium carbonate in an aqueous solution. Diluted water glass was added, and the solution pH was adjusted to about 7 to precipitate PVA-MBA modified mesoporous silica (PVA-MBA@SiO₂) granules. N-Halamine-grafted silica (PVA-MBA-Cl@SiO₂) granules were achieved by adding diluted sodium hypochlorite solution. It was found that a BET surface area of about 380 m² g^-1 for PVA-MBA@SiO₂ granules and a Cl⁺% of about 3.80% for PVA-MBA-Cl@SiO₂ granules could be achieved under optimized preparation conditions. Antimicrobial tests showed that the as-prepared antimicrobial silica granules were capable of about a 6-log inactivation of Staphylococcus aureus and Escherichia coli O157:H7 within 10 min of contact. Furthermore, the as-prepared antimicrobial silica granules can be recycled many times due to the excellent regenerability of their N-halamine functional groups and can be saved for a long time. With the above-mentioned advantages, the granules have potential applications in water disinfection.

Quaternary Ammonium Salts: Insights into Synthesis and New Directions in Antibacterial Applications

The overuse of antibiotics has led to the emergence of a large number of antibiotic-resistant genes in bacteria, and increasing evidence indicates that a fungicide with an antibacterial mechanism different from that of antibiotics is needed. Quaternary ammonium salts (QASs) are a biparental substance with good antibacterial properties that kills bacteria through simple electrostatic adsorption and insertion into cell membranes/altering of cell membrane permeability. Therefore, the probability of bacteria developing drug resistance is greatly reduced. In this review, we focus on the synthesis and application of single-chain QASs, double-chain QASs, heterocyclic QASs, and gemini QASs (GQASs). Some possible structure-function relationships of QASs are also summarized. As such, we hope this review will provide insight for researchers to explore more applications of QASs in the field of antimicrobials with the aim of developing systems for clinical applications.

QCM-Based HCl Gas Detection on Dimethylamine-Functionalized Crosslinked Copolymer Films

In this work, sensing behaviors and mechanisms of two crosslinked copolymers with dimethylamine and dimethylamide functional groups were compared and investigated for their ability to detect hydrogen chloride (HCl) gas. The crosslinked copolymer films were photopolymerized on quartz crystal electrodes using a micro-contact printing technique. The gas sensing behaviors were analyzed by measuring resonant frequency (Δf) of quartz crystal microbalance (QCM). The HCl binding capacity of photopolymerized films, with a mass between 4.6 and 5.9 μg, was optimized. Under optimized film mass conditions, the poly(2-dimethylaminoethyl methacrylate-co-ethylene glycol dimethacrylate) (DMAEMA-co-EGDMA), poly(DMAEMA-co-EGDMA), film, C2-DMA, showed a 13.9-fold higher binding capacity than the poly(N,N-dimethylacrylamide-co-ethylene glycol dimethacrylate, poly(DMAA-co-EGDMA), film, C0-DMA, during HCl gas adsorption. HCl gas was effectively adsorbed on the C2-DMA film because of the formation of tertiary amine salts through protonation and strong ionic bonding. Furthermore, the C2-DMA film exhibited excellent sensitivity, of 2.51 (ng/μg) (1/ppm), and selectivity coefficient (k* = 12.6 for formaldehyde and 13.5 for hydrogen fluoride) compared to the C0-DMA film. According to the experimental results, and due to its high functionality and stability, the C2-DMA film-coated QC electrode could be used as an HCl gas sensor, with low-cost and simple preparation, in future endeavors.

An N-Halamine/Graphene Oxide-Functionalized Electrospun Polymer Membrane That Inactivates Bacteria on Contact and by Releasing Active Chlorine

The emergence of antibiotic-resistant "superbugs" in recent decades has led to widespread illness and death and is a major ongoing public health issue. Since traditional antimicrobials and antibiotics are in many cases showing limited or no effectiveness in fighting some emerging pathogens, there is an urgent need to develop and explore novel antibacterial agents that are both powerful and reliable. Combining two or more antibiotics or antimicrobials has become a hot topic in antibacterial research. In this contribution, we report on using a simple electrospinning technique to create an N-halamine/graphene oxide-modified polymer membrane with excellent antibacterial activity. With the assistance of advanced techniques, the as-obtained membrane was characterized in terms of its chemical composition, morphology, size, and the presence of active chlorine. Its antibacterial properties were tested with Escherichia coli (E. coli) as the model bacteria, using the colony-counting method. Interestingly, the final N-halamine/graphene oxide-based antibacterial fibrous membrane inactivated E. coli both on contact and by releasing active chlorine. We believe that the synergistic antimicrobial action of our as-fabricated fibrous membrane should have great potential for utilization in water disinfection, air purification, medical and healthcare products, textile products, and other antibacterial-associated fields.

Quaternary Ammonium Compounds (QACs) and Ionic Liquids (ILs) as Biocides: From Simple Antiseptics to Tunable Antimicrobials

Quaternary ammonium compounds (QACs) belong to a well-known class of cationic biocides with a broad spectrum of antimicrobial activity. They are used as essential components in surfactants, personal hygiene products, cosmetics, softeners, dyes, biological dyes, antiseptics, and disinfectants. Simple but varied in their structure, QACs are divided into several subclasses: Mono-, bis-, multi-, and poly-derivatives. Since the beginning of the 20th century, a significant amount of work has been dedicated to the advancement of this class of biocides. Thus, more than 700 articles on QACs were published only in 2020, according to the modern literature. The structural variability and diverse biological activity of ionic liquids (ILs) make them highly prospective for developing new types of biocides. QACs and ILs bear a common key element in the molecular structure-quaternary positively charged nitrogen atoms within a cyclic or acyclic structural framework. The state-of-the-art research level and paramount demand in modern society recall the rapid development of a new generation of tunable antimicrobials. This review focuses on the main QACs exhibiting antimicrobial and antifungal properties, commercial products based on QACs, and the latest discoveries in QACs and ILs connected with biocide development.

Structure-dependent antimicrobial mechanism of quaternary ammonium resins and a novel synthesis of highly efficient antimicrobial resin

The demand for powerful and multifunctional water-treatment materials and reagents is increasing, because we are facing worse raw water quality, various tolerant bacteria, and risky disinfection by-products (DBPs) in drinking water. Quaternary ammonium resins (QARs) are promising candidates for water disinfection and purification, but their limited bactericidal capacities are difficult to improve because of the lack of guidelines for enhancing antibacterial efficiency. Therefore, we first systematically studied the structure-dependent antimicrobial mechanism of QARs and found that the best resin skeleton is acrylic-type, the optimal bactericidal alkyl is hexyl or octyl, the most applicable sizes are 80-100 meshes, the best counter anion is iodide ion, and the optimum quaternization reagent is iodoalkane. Moreover, the antibacterial capacity was demonstrated to depend on surficial N⁺ groups, correlating with surficial N⁺ charge density (R² of 0.98) but not with exchange capacity (R² of 0.26), physical adsorption of resin skeleton, or electrostatic adsorption of N⁺ groups. Based on these principles, we synthesized a new resin, Ac-81, with a surficial antibacterial design, which simultaneously exhibited better antimicrobial efficiency (two orders of magnitude) as well as higher contaminant removal potential (61.92%) compared to the traditional Ac-8C antibacterial resin. Furthermore, the new resin showed remarkable broad-spectrum antibacterial effects against Gram-negative E. coli and P. aeruginosa and Gram-positive B. subtilis and S. aureus in simulated water and actual water. Simultaneously, water quality was significantly improved, with HCO₃^-, SO₄^2-, TN, TP, and TOC reduced by 79-90%, >99%, 66-85%, >99%, and 22-26%, respectively. Ac-81 is characterized by facile reusability, high treatment capacity of 1500 bed volume, and good adaptability for treating actual water, providing a promising alternative for drinking-water disinfection and purification.

Polymeric antibacterial materials: design, platforms and applications

Over the past decades, the morbidity and mortality caused by pathogen invasion remain stubbornly high even though medical care has increasingly improved worldwide. Besides, impacted by the ever-growing multidrug-resistant bacterial strains, the crisis owing to the abuse and misuse of antibiotics has been further exacerbated. Among the wide range of antibacterial strategies, polymeric antibacterial materials with diversified synthetic strategies exhibit unique advantages (e.g., their flexible structural design, processability and recyclability, tuneable platform construction, and safety) for extensive antibacterial fields as compared to low molecular weight organic or inorganic antibacterial materials. In this review, polymeric antibacterial materials are summarized in terms of four structure styles and the most representative material platforms to achieve specific antibacterial applications. The superiority and defects exhibited by various polymeric antibacterial materials are elucidated, and the design of various platforms to elevate their efficacy is also described. Moreover, the application scope of polymeric antibacterial materials is summarized with regard to tissue engineering, personal protection, and environmental security. In the last section, the subsequent challenges and direction of polymeric antibacterial materials are discussed. It is highly expected that this critical review will present an insight into the prospective development of antibacterial functional materials.

Long-Chained Pyridinium N-Chloramines: Synthesis and Remarkable Biocidal Efficacies for Antibacterial Application

Two types of long-chained pyridinium N-chloramines were designed and synthesised by covalent linking a N-chloramine unit and a long intact alkyl chain via varied alkylation of 3-hydroxypyridine. Preliminary antibacterial tests showed that both synthetic pyridinium N-chloramines exerted distinctively elevated biocidal efficacy in contrast to previously reported pyridinium N-chloramines that lack a long chain. Such enhanced bactericidal behaviour was probably caused by ‘synergistic’ biocidal action between the N-chloramine moiety and the long-chained pyridinium moiety.

Advancements in the Development of Non-Nitrogen-Based Amphiphilic Antiseptics to Overcome Pathogenic Bacterial Resistance

The prevalence of quaternary ammonium compounds (QACs) as common disinfecting agents for the past century has led bacteria to develop resistance to such compounds. Given the alarming increase in resistant strains, new strategies are required to combat this rise in resistance. Recent efforts to probe and combat bacterial resistance have focused on studies of multiQACs. Relatively unexplored, however, have been changes to the primary atom bearing positive charge in these antiseptics. Here we review the current state of the field of both phosphonium and sulfonium amphiphilic antiseptics, both of which hold promise as novel means to address bacterial resistance.

Surficial N+ charge density indicating antibacterial capacity of quaternary ammonium resins in water environment

The antibacterial effects of quaternary ammonium resins (QARs) have been reported for decades, but there are few practical applications because of limited improvements in bactericidal capacity and the absence of an efficient antibacterial-indicating parameter. An in-situ determination method of surficial N⁺ groups for QARs, defined as surficial N⁺ charge density, was first established to merely quantify the exposed surficial quaternary ammonium groups (QAs). The mechanism of the new method depends on the tetraphenylboron sodium standard solution (TS), which is a colloidal solution with high steric hindrance, making it difficult to permeate into QARs and further react with the inner QAs. The results showed that the antibacterial efficacy of QARs correlates with the surficial N⁺ charge density with R² > 0.95 (R² of 0.97 for Escherichia coli, R² of 0.96 for Staphylococcus aureus) but not with the strong-base group exchange capacity or zeta potential. Furthermore, the surficial N⁺ charge density was demonstrated efficient to indicate the antibacterial capacities against both gram-negative and gram-positive bacteria for commercial QARs, including acrylic, styrene and pyridine resin skeletons, especially for the QARs with similar skeletons and similar QAs. Based on the finding that the bactericidal groups merely involve the surficial QAs of QARs, this study proposes a new direction for improving the antibacterial capacity by enriching the surficial QAs and enhancing the bactericidal property of these surficial QAs, and provides a practicable synthesis with two-step quaternization.

Porous antimicrobial starch particles containing N-halamine functional groups

The porous antimicrobial starch particles containing N-Halamine functional groups (PST-MBA-Cl particles) were synthesized by a crosslinking polymerization between starch (ST) and N, N'-methylenebisacrylamide (MBA), and then a chlorination of amide groups of MBA. The synthetic process used only water as the solvent and was environmentally friendly. The results showed that under the optimal preparation conditions, the as-synthesized PST-MBA-Cl particles could have a Cl⁺% of 8.60 %. Antimicrobial tests showed that PST-MBA-Cl particles had very powerful antimicrobial efficacy against both Staphylococcus aureus and Escherichia coli and could completely kill Staphylococcus aureus with a concentration of 2.1 × 10⁶ CFU/mL and Escherichia coli with a concentration of 5.6 × 10⁶ CFU/mL within a contact time of one minute. Furthermore, the N-Halamine functional groups of PST-MBA-Cl particles also showed excellent stability under storage and reproducibility. Therefore, the as-synthesized PST-MBA-Cl particles will have potential applications in water disinfection.

Synthesis of sulfonium N-chloramines for antibacterial applications

Sulfonium N-chloramines were synthesized with significantly higher antibacterial efficacy than previous quaternary ammonium counterpart 1, and the highest efficacy was achieved for dodecyl chained N-chloramine 9 due to a synergistic biocidal effect.

Combinations of Antimicrobial Polymers with Nanomaterials and Bioactives to Improve Biocidal Therapies

The rise of antibiotic-resistant microorganisms has become a critical issue in recent years and has promoted substantial research efforts directed to the development of more effective antimicrobial therapies utilizing different bactericidal mechanisms to neutralize infectious diseases. Modern approaches employ at least two mixed bioactive agents to enhance bactericidal effects. However, the combinations of drugs may not always show a synergistic effect, and further, could also produce adverse effects or stimulate negative outcomes. Therefore, investigations providing insights into the effective utilization of combinations of biocidal agents are of great interest. Sometimes, combination therapy is needed to avoid resistance development in difficult-to-treat infections or biofilm-associated infections treated with common biocides. Thus, this contribution reviews the literature reports discussing the usage of antimicrobial polymers along with nanomaterials or other inhibitors for the development of more potent biocidal therapies.

Electrospun Sesbania Gum-Based Polymeric N-Halamines for Antibacterial Applications

Microorganism pollution induced by pathogens has become a serious concern in recent years. In response, research on antibacterial N-halamines has made impressive progress in developing ways to combat this pollution. While synthetic polymer-based N-halamines have been widely developed and in some cases even commercialized, N-halamines based on naturally occurring polymers remain underexplored. In this contribution, we report for the first time on a strategy for developing sesbania gum (SG)-based polymeric N-halamines by a four-step approach Using SG as the initial polymer, we obtained SG-based polymeric N-halamines (abbreviated as cSG-PAN nanofibers) via a step-by-step controllable synthesis process. With the assistance of advanced techniques, the as-synthesized cSG-PAN nanofibers were systematically characterized in terms of their chemical composition and morphology. In a series of antibacterial and cytotoxicity evaluations, the as-obtained cSG-PAN nanofibers displayed good antibacterial activity against Escherichia coli and Staphylococcus aureus, as well as low cytotoxicity towards A549 cells. We believe this study offers a guide for developing naturally occurring polymer-based antibacterial N-halamines that have great potential for antibacterial applications.

Antimicrobial resins with quaternary ammonium salts as a supplement to combat the antibiotic resistome in drinking water treatment plants

The increasing finding of pathogens and antibiotic resistance genes (ARGs) in drinking water has become one of the most challenging global health threats worldwide. However, conventional disinfection strategies in drinking water treatment plants (DWTPs) require further optimization in combating the antibiotic resistome. Here, we show that antimicrobial resins with quaternary ammonium salts (AMRs-QAS) exhibit great potentials in diminishing specific potential pathogens that relatively resist chlorine or UV disinfection in DWTPs, and comprehensive analyses using microscopy and fluorescence techniques revealed that the antimicrobial capacity of AMRs-QAS mainly proceed via the bacterial adsorption and cell membrane dissociation. Moreover, a total of 15 among 30 selected ARGs, as well as 4 selected potential pathogens including Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli and Staphylococcus aureus were all detected in the source water. Coupling the AMRs-QAS with 0.2 mg/L chlorine resulted in higher removal efficiencies than chlorination (2 mg/L) or UV disinfection (400 mJ cm^-2) for all the detected pathogens and ARGs in drinking water and significantly decreased the relative abundances of Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, as well as all the detected ARGs (p < 0.05). Co-occurrences of pathogens and ARGs were revealed by a correlation network and possibly accounts for the ARGs removal. This coupled disinfection strategy overcomes the limitations of individual disinfection methods, i.e. the enrichment of specific pathogens and ARGs among bacterial populations, and provides an alternative for minimizing health risks induced by the antibiotic resistome in DWTPs.

Construction of Antibacterial N-Halamine Polymer Nanomaterials Capable of Bacterial Membrane Disruption for Efficient Anti-Infective Wound Therapy

The increasing occurrence of bacterial infection at the wound sites is a serious global problem, demanding the rapid development of new antibacterial materials for wound dressing to avoid the abuse of antibiotics and thereby antibiotic resistance. In this work, the authors first report on antibacterial N-halamine polymer nanomaterials based on a strategic copolymerization of 3-allyl-5,5-dimethylhydantoin (ADMH) and methyl methacrylate (MMA), which exhibits in vitro and in vivo antimicrobial efficacy against pathogenic bacteria including Staphylococcus aureus and Escherichia coli. Particularly, when a biological evaluation is run for wound therapy, the N-halamine polymer nanomaterials exhibit a powerful antibacterial efficiency and wound healing ability after a series of histological examination of mouse wound. After the evaluation of biological and chemical surroundings, the proposed four-stage mechanism suggests that, with unique antibacterial NCl bonds, the N-halamine polymer nanomaterials can disrupt the bacterial membrane, as a result causing intracellular content leaked out and thereby cell death. Based on the synergistic action of antibacterial and wound therapy, the N-halamine polymer nanomaterials are expected to be promising as wound dressing materials in medical healing and biomaterials.

Tailored synthesis of polymer-brush-grafted mesoporous silicas with N-halamine and quaternary ammonium groups for antimicrobial applications

Antimicrobial mesoporous materials with polymer brushes on the surface were prepared, and their structure and antimicrobial performance investigated. Poly ((3-acrylamidopropyl) trimethylammonium chloride) (PAPTMAC) modified mesoporous silica was prepared by a polymer-brush-grafted method through treatment with the initiator 4,4'-azobis (4-cyanovaleric acid) (ACVA) and polymerized with (3-acrylamidopropyl) trimethylammonium chloride (APTMAC). A covalent bond was formed between mesoporous silica and N-halamine precursor; N-H bonds were successfully transformed to N-Cl bonds after chlorination. Morphology and structure of mesoporous silica were affected to some extent after modification. The surface area of the polymerized sample decreased, but was sufficient for further applications. Compare to the original sample, antimicrobial properties of the polymerized samples with quaternary ammonium groups (QAS) increased slightly. After exposure to dilute household bleach, the chlorinated samples showed excellent antimicrobial properties against 100% of S. aureus (ATCC 6538) (7.63 log) and E. coli O157:H7 (ATCC 43895) (7.52 log) within 10 min. The prepared mesoporous silicas with effective antimicrobial properties could be very useful for potential application in water filtration.

Electrofabrication of functional materials: Chloramine-based antimicrobial film for infectious wound treatment

Electrical signals can be imposed with exquisite spatiotemporal control and provide exciting opportunities to create structure and confer function. Here, we report the use of electrical signals to program the fabrication of a chloramine wound dressing with high antimicrobial activity. This method involves two electrofabrication steps: (i) a cathodic electrodeposition of an aminopolysaccharide chitosan triggered by a localized region of high pH; and (ii) an anodic chlorination of the deposited film in the presence of chloride. This electrofabrication process is completed within several minutes and the chlorinated chitosan can be peeled from the electrode to yield a free-standing film. The presence of active NCl species in this electrofabricated film was confirmed with chlorination occurring first on the amine groups and then on the amide groups when large anodic charges were used. Electrofabrication is quantitatively controllable as the cathodic input controls film growth during deposition and the anodic input controls film chlorination. In vitro studies demonstrate that the chlorinated chitosan film has antimicrobial activities that depend on the chlorination degree. In vivo studies with a MRSA infected wound healing model indicate that the chlorinated chitosan film inhibited bacterial growth, induced less inflammation, developed reorganized epithelial and dermis structures, and thus promoted wound healing compared to a bare wound or wound treated with unmodified chitosan. These results demonstrate the fabrication of advanced functional materials (i.e., antimicrobial wound dressings) using controllable electrical signals to both organize structure through non-covalent interactions (i.e., induce chitosan's reversible self-assembly) and to initiate function-conferring covalent modifications (i.e., generate chloramine bonds). Potentially, electrofabrication may provide a simple, low cost and sustainable alternative for materials fabrication.

STATEMENT OF SIGNIFICANCE

We believe this work is novel because this is the first report (to our knowledge) that electronic signals enable the fabrication of advanced antimicrobial dressings with controlled structure and biological performance. We believe this work is significant because electrofabrication enables rapid, controllable and sustainable materials construction with reduced adverse environmental impacts while generating high performance materials for healthcare applications. More specifically, we report an electrofbrication of antimicrobial film that can promote wound healing.

A Schiff base/quaternary ammonium salt bifunctional graphene oxide as an efficient adsorbent for removal of Th(IV)/U(VI)

A novel approach for facile covalent functionalization of graphene oxide (GO) was proposed in the present study in order to effectively avoid necessary anhydrous conditions and the usage of harsh reagents during the chemical functionalization of GO. Herein, a GO derivative that was functionalized with a primary amine derivative bearing a positively charged quaternary ammonium group, GO-S, was synthesized through a Schiff base condensation reaction between the amine groups of the primary amine derivative and the aldehyde groups of GO. The introduction of the quaternary ammonium groups can prevent GO from stacking and improve the dispersibility of GO after modification. The formation of imine bonds (NCH) between the primary amine and GO has been confirmed by Fourier transform infrared and X-ray photoelectron spectroscopy. The GO-S demonstrated good dispersion stability in aqueous medium and also exhibited better adsorption performance than GO for Th(IV) and U(VI), with a maximum thorium adsorption capacity of 2.22mmol/g and a maximum uranium adsorption capacity of 0.83mmol/g, suggesting a great potential for the application of graphene oxide-based materials for facilitating the removal of Th(IV) and U(VI) from nuclear waste solutions.

Synthesis of quaternary phosphonium N-chloramine biocides for antimicrobial applications

We synthesized a phosphoniumN-chloramine biocide which has distinctively higher antimicrobial efficacy than the previously developed ammonium counterpart.

Design of polyurethane acrylic antimicrobial films via one-step UV curing

A series of films with excellent antimicrobial properties is prepared from QACs bearing hydrophobic tails and a polyurethane acrylate prepolymer via one-step UV curing.

N-Halamine-Containing Electrospun Fibers Kill Bacteria via a Contact/Release Co-Determined Antibacterial Pathway

N-Halamine-based antibacterial materials play a significant role in controlling microbial contamination, but their practical applications are limited because of their complicated synthetic process and indistinct antibacterial actions. In this study, novel antibacterial N-halamine-containing polymer fibers were synthesized via an one-step electrospinning of N-halamine-containing polymers without any additives. By adjusting the concentration of precursor and the molecular weight of polymers, the morphology and size of the as-spun N-halamine-containing fibers can be regulated. The as-spun fibers showed antibacterial activity against both Gram-positive and Gram-negative bacteria. After an antibacterial assessment using different biochemical techniques, a combined mechanism of contact/release co-determined killing action was evidenced for the as-spun N-halamine-containing fibers. With the aid of contact action and/or release action, this combined mechanism can allow N-halamines to attack bacteria, making the as-spun fibers wide in the application of antibacterial fields, whatever it is in dry or wet environment. Also, a recycle antibacterial test demonstrated that the as-spun fibers can still offer antibacterial property after five recycle experiments.

H5PMo10V2O40 immobilized on functionalized chloromethylated polystyrene by electrostatic interactions: a highly efficient and recyclable heterogeneous catalyst for hydroxylation of benzene

PMoV₂/DMA16-CMPS was used as a highly efficient and recyclable heterogeneous catalyst for hydroxylation of benzene.

Cytocompatible antibacterial fibrous membranes based on poly(3-hydroxybutyrate-co-4-hydroxybutyrate) and quaternarized N-halamine polymer

A novel polymeric N-halamine-containing quaternary ammonium salt (PHQS) was synthesized and used to make antibacterial electrospun fibrous membranes by blending with biodegradable poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB-4HB)).

Evaluation of Novel Antibacterial N-Halamine Nanoparticles Prodrugs towards Susceptibility of Escherichia coli Induced by DksA Protein

Novel N-halamine nanoparticles potentially useful for killing pathogenic bacteria, i.e., SiO2@PS/N-halamine NPs, were successfully synthesized via the immobilization of N-halamines onto the polystyrene-coated silica nanoparticles (SiO2@PS NPs). The effect of reaction conditions, i.e., chlorination temperature, bleaching concentration, chlorination time, on the oxidative chlorine content in the products was systematically investigated. The antibacterial activity of the products was tested via the modified plate counting methd using Escherichia coli (E. coli) as a model bacterium. The possible mechanism of the antibacterial action of the products was also studied using scanning electron microscopy combined with a inhibition zone study. The antimicrobial capability of the products was well controlled by tuning the oxidative chlorine content in the products. More importantly, the role of DksA protein in the susceptibility of E. coli against the products was proven using a time-kill assay. This in-depth investigation of the sensitivity of E. coli towards N-halamine NPs provides a systematic understanding of the utility of N-halamines for deactivating bacteria or even disease control.

Synthesis and bactericidal evaluation of imide N-halamine-loaded PMMA nanoparticles

Antibacterial imide N-halamine-loaded PMMA nanoparticles were fabricated, and their bactericidal activities were systematically evaluated.