Porous antimicrobial starch particles containing N-halamine functional groups

Nanofibers in Respiratory Masks: An Alternative to Prevent Pathogen Transmission

Recent global outbreak of COVID-19 has raised serious awareness about our abilities to protect ourselves from hazardous pathogens and volatile organic compounds. Evidence suggests that personal protection equipment such as respiratory masks can radically decrease rates of transmission and infections due to contagious pathogens. To increase filtration efficiency without compromising breathability, application of nanofibers in production of respiratory masks have been proposed. The emergence of nanofibers in the industry has since introduced a next generation of respiratory masks that promises improved filtration efficiency and breathability via nanometric pores and thin fiber thickness. In addition, the surface of nanofibers can be functionalized and enhanced to capture specific particles. In addition to conventional techniques such as melt-blown, respiratory masks by nanofibers have provided an opportunity to prevent pathogen transmission. As the surge in global demand for respiratory masks increases, herein, we reviewed recent advancement of nanofibers as an alternative technique to be used in respiratory mask production.

Construction of compostable packaging with antibacterial property and improved performance using sprayed coatings of modified cellulose nanocrystals

Increasing concerns about food safety and the environment have facilitated the development of eco-friendly antibacterial packaging. This study aimed to demonstrate a facile way to fabricate active packaging materials with modified cellulose nanocrystals (CNCs) and compare the effects of different modified CNCs on the performance of compostable materials. Polylactic acid (PLA) film was selected as a model, and CNCs were modified with methacrylamide, cetyltrimethylammonium bromide, and zinc oxide, respectively, and then applied on the surface of PLA films by spray-coating. All modified CNCs showed excellent antibacterial activity against S. aureus and E. coli (>99.999 %). The effects of different CNC modifications on the performance of PLA films were investigated. Compared to neat PLA films, PLA/CNC films exhibited improved mechanical strength with maintained flexibility, lower gas permeability, and faster compost disintegration rate, and extended the shelf life of wrapped pork samples from 3 days to >10 days. Therefore, this work will also facilitate the applications of PLA materials in eco-friendly packaging.

High-efficacy antimicrobial acyclic N-halamine-grafted polyvinyl alcohol film

With N,N'-methylenebisacrylamide (MBA) and polyvinyl alcohol (PVA) as raw materials, a polymer (PVA-MBA) containing N-halamine precursor functional groups was obtained via grafting reaction between the active hydroxyl groups on PVA and α, β-unsaturated functional groups of MBA under the catalysis of sodium carbonate in an aqueous solution. An acyclic N-halamine precursor-grafted PVA (MBA-PVA) film was formed by simply spreading PVA-MBA aqueous solution in a glass dish and drying it. An antimicrobial acyclic N-halamine-grafted PVA (PVA-MBA-Cl) film was achieved by spraying the diluted sodium hypochlorite solution onto the surface of PVA-MBA film. The performance test of PVA-MBA-Cl film under the optimal preparation conditions showed that the tensile performance and the hydrophobicity were improved, compared to the PVA film. The storage stability test indicated that the oxidative chlorine content Cl+ (atoms/cm2) of the as-prepared PVA-MBA-Cl film only reduced by 14.3% after storage for 9 weeks, showing that the antibacterial N-halamine functional groups in PVA-MBA-Cl film has excellent storage stability under room temperature. Antibacterial test showed that the PVA-MBA-Cl film had very strong antibacterial efficacies and could completely kill 1.28 × 106 CFU/mL S. aureus and 1.89 × 106 CFU/mL E. coli within 1 min. Therefore, PVA-MBA-Cl film will have more potential applications in food package.

Red mud conserved compost nitrogen by enhancing nitrogen fixation and inhibiting denitrification revealed via metagenomic analysis

The objective of this study was to investigate the effects of adding red mud (RM) on denitrification and nitrogen fixation in composting. The results revealed that the retentions of NH₄⁺-N and NO₃^--N in experimental group (T) with RM were 16.20% and 7.27% higher than that in control group (CK) at the mature stage, respectively. The composition and structure of RM can effectively inhibit denitrification and enhance nitrogen fixation. Moreover, metagenomic analysis revealed that Actinobacteria and Proteobacteria were the main microorganisms in denitrification process, while Firmicutes were the main microorganisms in nitrogen fixation process. In T, denitrifying genes nirK and nosZ were 11% and 18% lower than those in CK, respectively, while nitrogen-fixing genes nifK and nifD were 18% and 34% higher than those in control group, respectively. Therefore, adding RM could reduce nitrogen loss and improve the quality of compost via enhancing nitrogen fixation and inhibiting denitrification process.

Non-Leaching, Rapid Bactericidal and Biocompatible Polyester Fabrics Finished with Benzophenone Terminated N-halamine

Pathogenic bacteria can proliferate rapidly on porous fabrics to form bacterial plaques/biofilms, resulting in potential sources of cross-transmissions of diseases and increasing cross-infection in public environments. Many works on antibacterial modification of cotton fabrics have been reported, while very few works were reported to endow poly(ethylene terephthalate) (PET) fabrics with non-leaching antibacterial function without compromising their innate physicochemical properties though PET is the most widely used fabric. Therefore, it is urgent to impart the PET fabrics with non-leaching antibacterial activity. Herein, a novel N-halamine compound, 1-chloro-3-benzophenone-5,5-dimethylhydantoin (Cl-BPDMH), was developed to be covalently bonded onto PET fabrics, rendering non-leaching antibacterial activity while negligible cytotoxicity based on contact-killing principle. Bacterial was easily adhered to Cl-BPDMH finished PET fabrics, and then it was inactivated quickly within 10 s. Furthermore, the breaking strength, breaking elongation, tearing strength, water vapor permeability, air permeability and whiteness of Cl-BPDMH finished PET fabrics were improved obviously compared to raw PET fabrics. Hence, this work developed a facile approach to fabricate multifunctional synthetic textiles to render outstanding and rapid bactericidal activity without compromising their physicochemical properties and biocompatibility.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s42765-021-00100-z.

Development of PET Fabrics Containing N-halamine Compounds with Durable Antibacterial Property

Antibacterial textile materials are widely used in daily life, but most are disposable products with poor antibacterial durability. N-halamine can rapidly inactivate microorganisms, has good stability, and shows great potential applications in antibacterial fabrics. In this study, an N-halamine monomer precursor was synthesized and treated onto PET fabrics. The treated PET fabrics were rendered antibacterial functionality after chlorination, and exhibited good antibacterial properties with inactivation rate of 100.0 % for both E. coli O157:H7 and S. aureus. After 50 wash cycles, the chlorinated treated PET fabrics could maintain 80.0 % antibacterial efficacy, demonstrating durable antibacterial properties. Storage stability and UV irradiation tests showed that the treated PET fabrics had remarkable regenerable properties. The reduction of the breaking strength was within 12 % after treatment, which is in a satisfying range in antimicrobial finishing.