Glycopolymer N-halamine-modified biochars with high specificity for Escherichia coli eradication

Antibiotic-resistant bacteria contamination in environments imposes great threats to human life health.This research aims to develop novel targeted antibacterial biochars for achieving high selectivity to kill pathogenic Escherichia coli(E.coli).The glycopolymer N-halamine-modified biochars(i.e.,BCPMA-Cl)were synthesized by the modification of biochars with poly[2-(methacrylamido)glucopyranose-coacrylamide](P(MAG-co-AM),followed by chlorination treatment.Based on the results of FTIR,turbidity,XPS,and UV–vis,BCPMA-Cl was successfully synthesized and demonstrated to be able to eliminate Staphylococcus aureus(S.aureus)and E.coli.Especially,BCPMA-Cl possessed extremely potent to specific-killing 10^(4) CFU·ml^(-1) of E.coli with lower hemolytic activity(<5%).Additionally,the antibacterial mechanisms of BCPMA-Cl against bacteria were contact-killing and release-killing contributed by active chlorine(i.e.,Cl^(+)).Therefore,this work provided a cost-effective and facile approach for preparation of functional biochars used for bacteria-specific therapeutic applications via livestock pollutants as well as showing a promising strategy to avoid bacterial resistance.

Antibacterial Cellulose Coated with N-halamine by Pad-Cure Process

In order to improve the antibacterial property of cellulose,a new N-halamine antibacterial material precursor was synthesized.1,2,3,4-Butanetetracarboxylic acid( BTCA) was used to attach the N-halamine precursor onto cotton fabric as the cross-linking agent. The synthesized compound was characterized by1 H nuclear magnetic resonance(1H NMR). The cotton fabric treated with Nhalamine precursor was characterized by Fourier transform infrared spectroscopy( FT-IR) and scanning electron microscopy( SEM).The antimicrobial efficacy, washing durability and UVA light stability were investigated. The cotton fabric treated with the Nhalamine precursor could be rendered biocidal after exposure to dilute household bleach. The chlorinated cotton fabric shows great antimicrobial efficacy,100% of Staphylococcus aureus( S. aureus)with 1.00 ×10~7 CFU and 99. 998% of Escherichia coli (E. coli)O157∶H7 with 2. 20 × 10~7 CFU can be inactivated with 30 min of contact. Washing durability tests indicate that over 55% of the chlorine can be regained upon rechlorination after 50 washing cycles,and UVA light stability tests show that over 62% of the chlorine can be regenerated after irradiation of 12 h.

Electro-spinning Antimicrobial N-halamine Modified Poly(vinyl alcohol)Nanofibers

Antimicrobial poly( vinyl alcohol)( PVA) nanofibrous composites were prepared by adding 3-( 2,3-dihydroxypropyl)-5,5-dimethylimidazolidine-2,4-dione( N-halamine diol) to the PVA solution using electro-spinning technique upon curing and exposure to diluted sodium hypochlorite. Scanning electron microscopy( SEM) demonstrates that PVA nanofibers formed with diameters of( 255 ±94) nm. Cross-linked PVA nanofibers with N-halamine diol precursor and 1,2,3,4-butanetetracarboxylic( BTCA) showed good water resistance. The chlorinated PVA nanofibrous mats completely inactivated Staphylococcus aureus( Gram-positive) and Escherichia coli O157: H7( Gram-negative) with 7 log reductions( the reduction of the bacterial concentration in logarithm) within 5min and 1 min of contact time,respectively.

Electrospun N-halamine/ZnO-based platform eradicates bacteria through multimodal antimicrobial mechanism of action

The emergence and prevalence of antibiotic-resistant bacteria demands powerful antibacterial tactics to combat infectious microorganisms.Enhanced combinational therapy based on synergistic hybrid antibacterial materials is a promising approach to realize effective sterilization through the rational integration of distinct bactericides into one compact platform.In this work,we constructed a microfiber-based antibacterial platform(PAM-Cl/ZnO MFs)by electrospinning N-halamine polymers(PAM-Cl)loaded with zinc oxide(ZnO)nanoparticles.The as-designed PAM-Cl/ZnO MFs inherited the intrinsic antibacterial effects of both PAM-Cl microfibers(PAM-Cl MFs)and ZnO microfibers(ZnO MFs),and the material exhibited enhanced synergistic antibacterial performance against Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli)in vitro.The bactericidal effect was multimodal and included contact killing based on the N-Cl bond of N-halamine,multiple-release killing,such as reactive oxygen species(ROS)under light irritation,and Zn^(2+)and Cl^(+)acting as antibacterial agents.Importantly,PAM-Cl/Zno MFs worked on inactivate bacteria even under harsh temperatures and atmospheric conditions.Additionally,PAM-Cl/ZnO MFs exhibited good biocompatibility and performed outstanding acceleration of wound healing with in vivo mouse skin defect models using S.aureus.This work advances the design of antibacterial hybrid materials with the potency to eradicate bacteria in biological systems in multiple settings through the superiority of multimodal synergistic therapy.

Preparation of quaternarized N-halamine-grafted graphene oxide nanocomposites and synergetic antibacterial properties

At present,frequent outbreaks of bacteria and viruses have seriously affected people's normal lives.Therefore,the study of broad-spectrum antibacterial nanocomposites is very promising.However,most antibacterial materials have some disadvantages,such as single bactericidal mechanisms and unrepeatable use.Based on the current situation,a kind of nanocomposite with three structures of graphene oxide(GO),quaternary ammonium salt(QAs)and N-halamine was prepared,which showed synergistic effect to improve antibacterial activity and combined with a variety of sterilization mechanisms.Meanwhile,GO can provide richer ways of sterilization and high specific surface area,which is conducive to the grafting of quaternarized N-halamine.The advantages of physical sterilization of GO,charge adsorption of QAs,reuse of N-halamine and efficient sterilization are fully utilized.The results showed that the quaternarized N-halamine-grafted GO was obtained successfully.GO grafted with quaternarized N-halamine polymer showed strong speedy bactericidal activity against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)(99%).It had good storage and regeneration properties.

新合成橡胶可触杀细菌

Aubum大学的Sehelby Davis Worley博士报告，他们的实验证明，向含有聚苯乙烯的橡胶中加入氯和与有氯结合的N-halamines，这种经过改造的橡胶可在30分钟内杀死高浓度的病原菌。经过一段时间橡胶中的氯气耗尽，仅将其浸入家用浓度的氯漂白剂中就可恢复。母亲每个月可以将橡胶奶头浸入氯漂白剂一次，

Promotion of reactive oxygen species activated by nanosilver surface engineering for resistant bacteria-infected skin tissue therapy

Nanosilver has been regarded as a promising alternative to traditional antibiotics for fighting pathogenassociated infections due to its efficacy toward a broad spectrum of pathogens.However,bacterial resistance to nanosilver has emerged recently.In this contribution,a surface engineering strategy based on N-halamine chemistry to address bacterial resistance to nanosilver was proposed.Using 1,3-dichloro-5,5-dimethylhydantoin(DCDMH)as an N-halamine source,AgCI nanodots were deposited on the surface of Ag nano wires(Ag NWs)via in situ redox reaction to prepare AgCl-on-Ag NWs.After in vitro and in vivo tests,AgCl-on-Ag NWs effectively inactivated two antibiotic-resistant bacteria,ampicillinresistant Escherichia coli(AREC)and methicillin-resistant Staphylococcus aureus(MRSA)with the minimum bactericidal concentration(MBC)as low as 10μg·ml~(-1)and exhibited good biosafety against normal cells.The experimental and theoretical tests demonstrated that AgCl-onAg NWs worked on AREC and MAS A by generating high level of reactive oxygen species under visible light irradiation,coupled with the sustained Ag ion release.Meanwhile,the antibacterial mechanism of AgCl-on-Ag NWs against MRSA was verified at the gene level by transcriptome analysis(RNA sequencing).Moreover,the fullthickness defect model verified that AgCl-on-Ag NWs reduced inflammatory cell infiltration and dramatically accelerated wound healing.This work provides a synergistic mechanism based on nanosilver surface engineering to eradicate the resistant bacteria that can alleviate drug resistance and develop an innovative approach for the treatment of bacterial infections.

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/bioflms,resulting in potential sources of cross-transmissions of diseases and increasing cross-infection in public environments.Many works on antibacterial modifcation 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 fnished 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 fnished 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.

FUNCTIONALIZING PS MICROSPHERES BY SUPERCRITICAL DEPOSITION OF P(S-b-tBA) FOR DIVERSE INTERFACIAL PROPERTIES EXEMPLIFIED WITH BIOCIDAL ABILITY

Polystyrene （PS） microsphel＂es were functionalized with poly（styrene-b-tert-butyl acrylate） （P（S-b-tBA）） by adsorption from supereritical mixture of CO2 and hexane. Supercritical deposition formed a shell-core structure that contained a shell ofpoly（tert-butyl acrylate） （PtBA） blocks and a core of the PS blocks entangling with the PS microspheres. The thickness of the PtBA layer and thereby the areal density of ten-butyl ester groups increased v;ith the deposition pressure until plateau values attained at 20 MPa and higher. The tert-butyl ester groups were hydrolyzed to earboxyl groups for conjugation with tert-butylamine molecules via amide bonds that were further chlorinated into biocidal N-halamine moieties. The functionalization layer and its bonded N-halamine moieties were stable in flowing watel and the chlorine could be regenerated upon eventual loss. This functionalization concept is applicable to polymers of any external and internal surfaces to achieve diverse surface properties by varying block eopolymer and conjugated mo：ieties.