Search Results (5)

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. Full article

Reducing microbial infections associated with biomedical devices or articles/furniture noted in a hospital or outpatient clinic remains a great challenge to researchers. Due to its stability and low toxicity, the N-halamine compound has been proposed as a potential antimicrobial agent. It can be incorporated into or blended with the FDA-approved biomaterials. Surface grafting or coating of N-halamine was also reported. Nevertheless, the hydrophobic nature associated with its chemical configuration may affect the microbial interactions with the chlorinated N-halamine-containing substrate. In this study, a polymerizable N-halamine compound was synthesized and grafted onto a polyurethane surface via a surface-initiated atom transfer radical polymerization (SI-ATRP) scheme. Further, using the sequential SI-ATRP reaction method, different hydrophilic monomers, namely poly (ethylene glycol) methacrylate (PEGMA), hydroxyethyl methacrylate (HEMA), and [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA), were also grafted onto the polyurethane (PU) substrate before the N-halamine grafting reaction to change the surface properties of the N-halamine-modified substrate. It was noted that the chains containing the hydrophilic monomer and the polymerizable N-halamine compound were successfully grafted onto the PU substrate. The degree of chlorination was improved with the introduction of a hydrophilic monomer, except the HEMA. All of these hydrophilic monomer-containing N-halamine-modified PU substrates demonstrated a more than 2 log CFU reduction after microbial incubation. In contrast, the surface modified with N-halamine only exhibited significantly less antimicrobial efficacy instead. This is likely due to the synergistic effects caused by the reduced chlorine content, as well as the reduced surface interactions with the microbes. Full article

Microbial contamination is a significant issue in various areas, especially in the food industry. In this study, to overcome microbial contamination, cross-linked polymer brushes containing N-halamine were synthesized, characterized, and investigated for antibacterial properties. The cross-linked polymer brushes with different N-halamine ratios were synthesized by in-situ cross-linking methods with reversible addition−fragmentation chain transfer (RAFT) polymerization using a bifunctional cross-linker. The RAFT agent was immobilized on an amine-terminated silicon wafer surface and utilized in the surface-initiated RAFT polymerization of [N-(2-methyl-1-(4-methyl-2,5-dioxoimidazolidin-4-yl)propane-2-yl)acrylamide] (hydantoin acrylamide, HA), and N-(2-hydroxypropyl)methacrylamide) (HPMA) monomers. Measurement of film thickness, contact angle, and surface morphology of the resulting surfaces were used to confirm the structural characteristics of cross-linked polymer brushes. The chlorine content of the three different surfaces was determined to be approximately 8–31 × 10¹³ atoms/cm². At the same time, it was also observed that the activation–deactivation efficiency decreased during the recharge–discharge cycles. However, it was determined that the prepared N-halamine-containing cross-linked polymer brushes inactivated approximately 96% of Escherichia coli and 91% of Staphylococcus aureus. In conclusion, in the framework of this study, high-performance brush gels were produced that can be used on antibacterial surfaces. Full article

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. Full article

Rechargeable disinfectant performance of a microfiber fabric grafted with a halamine precursor, 3-allyl-5,5-dimethylhydantoin (ADMH), was tested in an actual use situation in a university student dining hall. The precursor was successfully incorporated onto the surfaces of polyester fibers by using a radical graft polymerization process through a commercial finishing facility. The N–H bonds of ADMH moieties on the fibers can be converted to biocidal N–Cl bonds, when the fabrics are washed in a diluted chlorine bleach containing 3000 ppm available chlorine, providing a refreshable disinfectant function. By wiping the surfaces of 30 tables (equivalent to 18 m²) with wet chlorinated fabrics, both Staphylococcus aureus and Escherichia coli in concentrations of 10⁵ CFU/mL were totally killed in a contact time of 3 min. The disinfectant properties of the fabrics were still superior after 10 times successive machine washes (equivalent to fifty household machine washes), and rechargeable after wiping 30 tables before each recharge. Recharging conditions, such as temperature, time, active chlorine concentration and pH value of sodium hypochlorite solution, as well as the addition of a detergent, were studied. The product has the potential to improve public safety against biological contaminations and the transmission of diseases. Full article