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.

Recovery and in-situ reduction of precious metals by graphdiyne and graphdiyne oxide for antibacterial use

Based on the in-situ self-reduction and chemical stability,graphdiyne(GDY)and graphdiyne oxide(GDYO)are used as trapping agents to investigate the ability for recovering Au^(3+),Ag^+,and Pd^(2+)under different pH values and interfering ions.Under strong acidity at pH=1,these two agents demonstrate high select recovery towards the three precious metal ions,which could be insitu reduced to nanoparticles(NPs).In addition,superparamagnetic Fe_(3)O_(4)NPs are deposited on the surfaces of GDY and GDYO.The magnetic responses enable GDYFe_(3)O_(4)to recover precious metals conveniently and efficiently by the aid of an external magnetic field.This study also confirms the antibacterial activity of the as-recovered NPs deposited on GDY and GDYO against Escherichia coli and Staphylococcus aureus(1×10^(5)colony-forming unit(CFU)·mL^(-1)),and the antibacterial rates are 100%.This strategy of recovering precious metals and subsequently reusing to combat pathogens will be of great significance for environmental remediation and biomedical applications.

Ag/AgX nanostructures serving as antibacterial agents:achievements and challenges

Bacterial infections,especially the frequently emerging "superbugs",seriously affect the quality of human life and even threaten human health.As the emerging antimicrobial agents that effectively eradicate pathogens,nanomaterials have been widely explored due to their effectiveness against wide-spectrum bacteria and“superbugs”.Of them,Ag/AgX nanostructures(X representing Cl,Br or I)have emerged as an excellent antibacterial agent because of their excellent photocatalytic performance in inactivating pathogens under light irradiation,which provides a new opportunity for the development of high-efficient visible-light driven photocatalytic sterilization.To date,Ag/AgX nanostructures have been widely employed in antibacterial associated fields because they are efficient in producing reactive oxygen species(ROS)and reactive chlorine species(RCS)under visible light irradiation.In this review,we summarized the recent progress of Ag/AgX nanostructures as plasmonic photocatalysts in the antibacterial field,focusing on the antibacterial effects and mechanisms of Ag/AgX nanostructures,as well as their potent applications.Finally,the challenges and prospects of Ag/AgX nanostructures acting as active antibacterial agents were discussed.

Cow dung-derived biochars engineered as antibacterial agents for bacterial decontamination

Disposal of the pollutants arising from farming cattle and other livestock threatens the environment and public safety in diverse ways.Herein,we report on the synthesis of engineered biochars using cow dung as raw material,and investigating these biochars as antibacterial agents for water decontamination.By coating the biochars with N-halamine polymer and loading them with active chlorine (i.e.,Cl+),we were able to regulate them on demand by tuning the polymer coating and bleaching conditions.The obtained N-halamine-modified biochars were found to be extremely potent against Escherichia coli and Staphylococcus aureus.We also investigated the possibility of using these N-halamine-modified biochars for bacterial decontamination in real-world applications.Our findings indicated that a homemade filter column packed with N-halamine-modified biochars removed pathogenic bacteria from mining sewage,dairy sewage,domestic sewage,and artificial seawater.This proposed strategy could indicate a new way for utilizing livestock pollutants to create on-demand decontaminants.

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.

Dual Functional Diblock Amino Acid Copolymer Displaying Synergistic Effect with Curcumin against MRSA and Encapsulation of Curcumin

The intensive use of antibiotics intensifies the development of bacterial resistance,which has become a serious problem globally.Methicillin-resistant Staphylococcus aureus(MRSA)has resulted in significant morbidity and mortality.Therefore,it is an urgent need to develop new antimicrobial drugs and administration methods.Herein,we report a dual functional diblock copolymer PLL20-b-PBLG20,which was prepared by superfast and water-insensitive polymerization on N-carboxyanhydrides(NCA)initiated by tetraalkylammonium carboxylate.In addition to direct antimicrobial activity,PLL20-b-PBLG20 also exerts a synergistic bactericidal effect against MRSA with curcumin,a plant extract with antibacterial property.Moreover,PLL20-b-PBLG20 successfully encapsulates curcumin to form nanoparticles via self-assembly.The combination of dual functional PLL20-b-PBLG20 and curcumin holds promise in combating MRSA infections.

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.