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Abstract It is of great significance to develop a novel approach to treat bacterial infections, as the frequent misuse of antibiotics leads to the serious problem of bacterial resistance. This study proposed antibiotic-free antibacterial nanoparticles for eliminating methicillin-resistant Staphylococcus aureus (MRSA) based on a multi-model synergistic antibacterial ability of chemodynamic therapy (CDT), photothermal effect, and innate immunomodulation. Specifically, a polydopamine (PDA) layer coated and Ag nanoparticles loaded core-shell structure Fe3O4 nanoparticles (Fe3O4@PDA-Ag) is prepared. The Fe3O4 catalyzes H2O2 present in acidic microenvironment of bacterial infection into more toxic reactive oxygen species (ROS) and synergizes with the released Ag ions to exert a stronger bactericidal capacity, which can be augmented by photothermal action of PDA triggered by near-infrared light and loosen the biofilm by photothermal action to promote the penetration of ROS and Ag ion into the biofilm, result in disrupting biofilm structure along with killing encapsulated bacteria. Furthermore, Fe3O4@PDA-Ag exerts indirect antibacterial effects by promoting M1 macrophage polarizing. Animal models demonstrated that Fe3O4@PDA-Ag effectively controlled MRSA-induced infections through photothermal enhanced CDT, Ag+ releasing, and macrophage-mediated bactericidal properties. The acid-triggered antibacterial nanoparticles are expected to combat drug-resistant bacteria infection. Graphical abstract

In this study, a SiO2 support was modified with zinc and cerium to obtain a material with excellent antibacterial properties. The optimal preparation conditions resulting in the highest antibacterial efficiency (cZn = 0.83 M, cCe = 0.005 M, reaction time = 1.6 h) were identified by applying response surface methodology. The antibacterial experiments were carried out based on the coating plate method using Escherichia coli. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses revealed an evenly distributed composition with a lamellar structure in the samples. Further analysis through X-ray photoelectron spectroscopy (XPS) indicated that zinc and cerium were successfully modified onto the silica carriers in the form of oxides. The high percentage of Ce4+/Ce3+ ions promotes an increase in anti-inflammatory cytokines and a decrease in pro-inflammatory cytokines, thereby enhancing antimicrobial properties. The detection of ion dissolution and specific surface area and particle size explained that the addition of cerium promoted the loading and release of antimicrobial zinc ions. The introduction of cerium into the ZnO lattice results in the replacement of zinc atomic sites with cerium atomic sites. This substitution causes disorganization in the arrangement of zinc ions in certain regions, leading to a weakening of the Zn–O bond and an increased release of zinc ions. The content of zinc ions increased from 1.06% to 1.79%, which increased the specific surface area of the composites from 214.50803 m2/g to 308.86977 m2/g, which gave the materials high adsorption properties, thus improving their antimicrobial performance. Combined with the positive synergistic effect factor and synergistic coefficient of 1.89 calculated by the response surface method, it was observed that a notable synergistic effect exists between zinc and cerium. [ABSTRACT FROM AUTHOR]

It is of great significance to develop a novel approach to treat bacterial infections, as the frequent misuse of antibiotics leads to the serious problem of bacterial resistance. This study proposed antibiotic-free antibacterial nanoparticles for eliminating methicillin-resistant Staphylococcus aureus (MRSA) based on a multi-model synergistic antibacterial ability of chemodynamic therapy (CDT), photothermal effect, and innate immunomodulation. Specifically, a polydopamine (PDA) layer coated and Ag nanoparticles loaded core-shell structure Fe3O4 nanoparticles (Fe3O4@PDA-Ag) is prepared. The Fe3O4 catalyzes H2O2 present in acidic microenvironment of bacterial infection into more toxic reactive oxygen species (ROS) and synergizes with the released Ag ions to exert a stronger bactericidal capacity, which can be augmented by photothermal action of PDA triggered by near-infrared light and loosen the biofilm by photothermal action to promote the penetration of ROS and Ag ion into the biofilm, result in disrupting biofilm structure along with killing encapsulated bacteria. Furthermore, Fe3O4@PDA-Ag exerts indirect antibacterial effects by promoting M1 macrophage polarizing. Animal models demonstrated that Fe3O4@PDA-Ag effectively controlled MRSA-induced infections through photothermal enhanced CDT, Ag+ releasing, and macrophage-mediated bactericidal properties. The acid-triggered antibacterial nanoparticles are expected to combat drug-resistant bacteria infection. [ABSTRACT FROM AUTHOR]

The problem of antibiotic misuse leading to bacterial resistance is a significant challenge currently faced. The rapid adaptability and evolutionary capabilities of microorganisms have caused strains that were initially sensitive to antibiotics to gradually become resistant, posing a threat to traditional antibacterial treatments. Therefore, the search for antibacterial treatment methods, especially those less likely to induce resistance, has become crucial. Photodynamic antibacterial therapy is an emerging method with efficient antibacterial and selective effects, reducing the risk of resistance. A two-dimensional nanocomposite material, modified with quaternized ruthenium complexes on MXene, has been developed. The minimum inhibitory concentrations against Escherichia coli and Staphylococcus aureus were found to be 23.4 and 29.0 μg/mL, respectively, under xenon lamp irradiation with a light power intensity of 100 mW/cm² for 20 min. The bactericidal effects of the Q/Ru-MXene composite system were quantitatively and qualitatively confirmed through plate counting and live/dead staining. This system integrates the chemical antibacterial properties of quaternary ammonium salts, the photodynamic antibacterial effects of ruthenium complexes, and the photothermal antibacterial properties of MXene. The simultaneous application of these three therapeutic approaches allows for the development of a chemical/photodynamic/photothermal antibacterial strategy that can attack bacteria on multiple levels, enhancing treatment efficacy, slowing down the development of bacterial resistance, and adapting better to different types of infections. Research and the application of this comprehensive strategy have the potential to bring breakthroughs and innovations to the field of antibacterial treatment. [ABSTRACT FROM AUTHOR]

Postharvest fruits, especially climacteric fruits, are prone to ethylene ripening, browning and aging, microbial growth accelerated decay and other problems in natural environment. Herein, a carboxylated cellulose nanofibers/phytic acid‑titanium dioxide nanoparticles (CPT) biodegradable coating with "photocatalytic antibacterial barrier" structure，was developed by homogeneous dispersion of phytic acid(PA) complexed titanium dioxide nanoparticles (TNPs) in carboxylated cellulose nanofibers(CCNF). The CPT coating achieves effective dispersion and efficient utilization of TNPs through the complexation of PA. The coating ethylene clearance rate of CPT up to 70.89 %. Meanwhile, the coating exhibits excellent antibacterial (99.67 %), UV resistance, gas barrier. It was found that the CPT coating delays fruit ripening caused by ethylene, which effectively maintaining the quality of respiratory climacteric fruits and non- climacteric fruits, extending the shelf life of perishable fruit by up to 9 days. In particular, the coating is virtually biodegradable in soil after 21 days, which offers the possibility of replacing non-biodegradable multifunctional coatings in food packaging. [Display omitted] • CPT coatings prepared by the one-pot method have excellent UV protection. • Coating has the ability to decompose ethylene and enhance antibacterial activity. • Synergistic effect of the coating for freshness preservation of different fruits. [ABSTRACT FROM AUTHOR]

The purpose of this study was to prepare Pickering emulsion with synergistic antibacterial effect using whey protein isolated-citral (WPI-Cit) nanoparticles with eugenol for grape preservation. In this emulsion, eugenol was encapsulated in oil phase. The particle size, ζ– potential, and antibacterial mechanism of the nanoparticles were characterized. The rheological properties, antibacterial effects and preservation effects of WPI-Cit Pickering emulsion were measured. The results showed that the optimal preparation condition was performed at WPI/Cit mass ratio of 1:1, WPI-Cit nanoparticles were found to damage the cell wall and membrane of bacteria and showed more effective inhibition against S. aureus. Pickering emulsion prepared with WPI-Cit nanoparticles exhibited a better antibacterial effect after eugenol was encapsulated in it, which extended the shelf life of grapes when the Pickering emulsion was applied as a coating. It demonstrated that the Pickering emulsion prepared in this study provides a new way to extend the shelf life. [Display omitted] • Whey protein isolate and citral nanoparticles were prepared by Schiff reaction. • Whey protein isolate and citral nanoparticles damaged bacteria cell wall and DNA. • Whey protein isolate-citral Pickering emulsion had antibacterial properties. • Whey protein isolate-citral Pickering emulsion and eugenol extend grape shelf life. [ABSTRACT FROM AUTHOR]

Excessive use of antibiotics and the formation of bacterial biofilms can lead to persistent infections caused by drug-resistant bacteria, rendering ineffective immune responses and even life-threatening. There is an urgent need to explore synergistic antibacterial therapies across all stages of infection. Drawing inspiration from the antibacterial properties of neutrophil extracellular traps (NETs) and integrating the bacterial biofilm dispersal mechanism involving boronic acid-catechol interaction, the multifunctional bismuth-based polypeptide nanonets (PLBA-Bi-Fe-TA) are developed. These nanonets are designed to capture bacteria through a coordination complex involving cationic polypeptides (PLBA) with boronic acid-functionalized side chains, alongside metal ions (bismuth (Bi) and iron (Fe)), and tannic acid (TA). Leveraging the nanoconfinement-enhanced high-contact network-driven multiple efficiency, PLBA-Bi-Fe-TA demonstrates the excellent ability to swiftly capture bacteria and their extracellular polysaccharides. This interaction culminates in the formation of a highly hydrophilic complex, effectively enabling the rapid inhibition and dispersion of antibiotic-resistant bacterial biofilms, while Fe-TA shows mild photothermal ability to further assist fluffy mature biofilm. In addition, Bi is beneficial to regulate the polarization of macrophages to pro-inflammatory phenotype to further kill escaping biofilm bacteria. In summary, this novel approach offers a promising bionic optimization strategy for treating bacterial-associated infections at all stages through synergetic treatment., (© 2024 Wiley‐VCH GmbH.)

Bacterial resistance to antibiotics can negatively affect the treatment of infected skin wounds. The combination of synergistic antibacterial therapies with photodynamic, photothermal, and chemodynamic therapies has been recognized as one of the most promising approaches. In this study, we have developed MSN@Ce6@MnO 2 -CS/Ag (MCMA) nanoparticles to serve as powerful antibacterial agents when exposed to both 660 nm visible light and 808 nm near-infrared (NIR) light. Through dual-light irradiation, MCMA can induce hyperthermia and generate reactive oxygen species (ROS), leading to a remarkable enhancement in photothermal antibacterial effects and accelerating wound healing. It has a peroxidase-like catalytic activity and promotes the generation of hydroxyl radicals (·OH) by catalyzing the decomposition of H 2 O 2 . In vitro antibacterial experiments demonstrated the excellent antibacterial activity of MCMA. The antibacterial efficacy of MCMA at a concentration of 250 μg ml -1 was found to be 99.6 and 100% toward Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli , respectively, under irradiation with an 808 and 660 nm laser. The results of the animal experiments demonstrated that MCMA can effectively accelerate wound healing through wound ulceration inhabitation. These findings substantiate the assertion that synthetic MCMA represents an efficacious strategy for bacterial inhibition and wound healing.

[Display omitted] • A novel MoS 2 /Cu 3 Mo 2 O 9 intelligent antibacterial nano-platform has been designed and synthesized based on DFT simulations. • The structure can effectively absorb near-infrared light, accelerate electron transfer, reduce migration resistance, and possess enhanced photothermal and photocatalytic antibacterial activity. • The structure features a unique 'activation' mechanism that can freely select and switch between 'passive defense,' 'secondary sterilization,' and 'active attack' antibacterial functions as needed. • The synergistic effect of multi-modal antibacterial capabilities was achieved, and the synergistic mechanism was investigated in detail. In this era of high drug resistance, there is an urgent need for novel antimicrobial agents and strategies to achieve smarter sterilization effects. However, developing an environmentally friendly, controllable, and self-cleaning smart antimicrobial material remains a formidable challenge. In this work, a smart antimicrobial nanoplatform composed of Cu 3 Mo 2 O 9 and MoS 2 has been successfully designed and synthesized. The computational findings reveal that, owing to the interfacial coupling between the two substances at the solid junction, this architecture can effectively absorb near-infrared light, significantly reduce migration resistance, and improve carrier separation efficiency. Empirical observations demonstrate that with a sample concentration of 100 μg/mL, under near-infrared (NIR) laser irradiation, the microenvironmental temperature proximal to the bacteria can be swiftly elevated from 28.6 °C to in excess of 50 °C within a mere 6 min. The overall photothermal conversion efficiency is 32.6 %, and it exhibits an active oxygen level nearly 5 times higher than that of Cu 3 Mo 2 O 9. Furthermore, the permeability of the cell membrane was greatly improved with the increased temperature, which is beneficial for the generated reactive oxygen species (ROS) entering the bacterial cells. After synergistic antimicrobial treatment, the antibacterial rate against Escherichia coli can reach over 99 %. More importantly, this nano-platform features a unique 'activation' mechanism that uses NIR as an 'activation switch' to selectively toggle between 'passive defense,' 'secondary sterilization,' and 'active attack' antibacterial modes as needed. Upon interaction with aqueous environments, its reusability and favorable biocompatibility with terrestrial and aquatic life promise to facilitate the intelligent eradication of deleterious microorganisms in aquatic systems via the diurnal cycle of sunrise and sunset. This is highly significant for the ongoing management and maintenance of public resources such as amusement parks, artificial fish ponds, and urban water features. [ABSTRACT FROM AUTHOR]

[Display omitted] • Multifunctional nanozymes with space-confinement effect were synthesized. • Space-confined nanozymes significantly improve catalytic effects. • Cascade nanozymes have synergistic antibacterial effects. • Nanozymes with nanoconfinement can be used for synergistic antibacterial treatment and fluorescence imaging of bacterial infections. The rapid development of bacterial infections has become a significant global health challenge. The overuse or prolonged use of antibiotics is considered a major contributor to the development of bacterial resistance. Therefore, there is an urgent need to develop a new therapeutic approach to combat infectious diseases caused by bacteria. In this study, we demonstrate the effectiveness of a novel strategy for synergistic antibacterial therapy and fluorescence imaging of wound bacterial infections through the nano-confined construction of LL-37-HA-Au-Pt@PCN-224 nanozymes. The nanozyme is composed of Au NPs and Pt NPs confined to PCN-224 through in situ reduction, with its outer layer modified with HA and LL-37. The nanozyme catalyzes the conversion of low-concentration H 2 O 2 into O 2 and •OH, with the generated O 2 further catalyzed into 1O 2 by PCN-224. In vivo imaging experiments demonstrate that LL-37-HA-Au-Pt@PCN-224 labeled with near-infrared fluorescent dye MPA can effectively realize fluorescence imaging of wound bacterial infections and real-time monitoring of the wound healing process. In vitro and in vivo antibacterial experiments reveal that LL-37-HA-Au-Pt@PCN-224 enhances the healing efficiency of bacteria-infected wounds due to its synergistic antibacterial effect. The multifunctional nanozyme offers various synergistic antibacterial therapies, including antimicrobial peptides, peroxide nanozymes, hydrogen peroxide nanozymes, and photodynamic therapy. Moreover, it provides real-time wound imaging and monitoring of the wound healing process, while maintaining high biocompatibility. Overall, this study presents a promising perspective on the potential use of nanozymes as antibacterial agents against wound bacterial infections in the future. [ABSTRACT FROM AUTHOR]

• Supramolecular binding strategy was developed to prepare novel COFs. • β-CD inclusion was used as building block for the preparation of COFs. • Por-CD-COF could greatly reduce the use of photoactive ingredients. • The threading of CD could significantly enhance the photoactivity of COFs. • Por-CD-COF exerted cyclodextrin enhanced PTT and PDT. As an emerging artificial porous material, covalent organic frameworks (COFs) with customizable structure and function, have always been the focus of polymer science. Controllable fabrication of COFs with brand-new structure is the top priority for its development. Here, the 'supramolecular binding' strategy is developed as a simple but efficient method to prepare COFs with novel structures and functions. By this means, polymeric rotaxanes threaded COFs, denoted as Por-CD-COF, was facilely prepared via the combination of dynamic covalent imine-bond formation with supramolecular self-assembly, in which the polyrotaxane formed via inclusion of aromatic linker with bactericidal active β-cyclodextrin macrocycle (CD) was condensed with the photosensitive porphyrin via the combination of mechanical grinding and solvothermal synthesis. The formation of polyrotaxane could change the distance between layers, avoiding the quench of photoactivity caused by the severe aggregation of layered structure. Under the same molar amount of reaction monomers, the weight of the Por-CD-COF is approaching five times of the CD-free COF, which could greatly reduce the use of photoactive ingredients. Further experiments demonstrated the introduction of CDs could also significantly improve the biocompatibility. Impressively, this special porphyrin-involved CD-COF, displays excellent photo activity, which could act as an efficient broad spectrum antibacterial agents realizing the combinational action of cyclodextrin enhanced photothermal and photodynamic antimicrobial at an extremely low quality of the effective photosensitizer (Porphyrin). Meanwhile, even at the same dose of fungicide, the bactericidal effect of Por-CD-COF is far exceeding the CD-free therapeutic agent. This novel synthetic strategy allows the incorporation of mechanically interlocked CDs (MIMs) into the porous polymeric materials, providing an easy access to low-cost preparation of COFs for the specific applications. [ABSTRACT FROM AUTHOR]

Bacterial biofilm formation is associated with the pathogenicity of pathogens and poses a serious threat to human health and clinical therapy. Complex biofilm structures provide physical barriers that inhibit antibiotic penetration and inactivate antibiotics via enzymatic breakdown. The development of biofilm-disrupting nanoparticles offers a promising strategy for combating biofilm infections. Hence, polyethyleneimine surface-modified silver-selenium nanocomposites, Ag@Se@PEI (ASP NCs), were designed for synergistic antibacterial effects by destroying bacterial biofilms to promote wound healing. The results of in vitro antimicrobial experiments showed that, ASP NCs achieved efficient antibacterial effects against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) by disrupting the formation of the bacterial biofilm, stimulating the outbreak of reactive oxygen species and destroying the integrity of bacterial cell membranes. The in-vivo bacterial infection in mice model showed that, ASP NCs further promoted wound healing and new tissue formation by reducing inflammatory factors and promoting collagen fiber formation which efficiently enhanced the antibacterial effect. Overall, ASP NCs possess low toxicity and minimal side effects, coupled with biocompatibility and efficient antibacterial properties. By disrupting biofilms and bacterial cell membranes, ASP NCs reduced inflammatory responses and accelerated the healing of infected wounds. This nanocomposite-based study offers new insights into antibacterial therapeutic strategies as potential alternatives to antibiotics for wound healing., (© 2024 IOP Publishing Ltd.)

Bacterial invasion hinders the healing process of wound, leading to the formation of chronic infected wound; meanwhile, the misuse of antibiotics has resulted in the emergence of numerous drug-resistant bacteria. The application of conventional antimicrobial methods and wound treatment techniques is not appropriate for wound dressings. In this paper, quaternized poly(vinyl alcohol) (QPVA) and pomegranate-like copper uniformly doped polydopamine nanoparticles (PDA@Cu) were introduced into a gelatin-oxidized carboxymethyl cellulose system to form a multicomponent synergistic antibacterial hydrogel (GOQ 3 P 3 ). Polydopamine improves the biocompatibility and prevents the detachment of Cu nanoparticles. It can achieve synergistic antibacterial effects through quaternary ammonium salt-inorganic nanoparticle photothermal treatment under 808 nm near-infrared (NIR) irradiation. It exhibits highly efficient and rapid bactericidal properties against Escherichia coli , Staphylococcus aureus , and MRSA (methicillin-resistant Staphylococcus aureus ) with an antibacterial rate close to 100%. The gel scaffold composed of macromolecules gives the hydrogel excellent mechanical properties, adhesive capabilities, self-healing characteristics, biocompatibility, and pH degradation and promotes cell adhesion and migration. In a full-thickness wound healing model infected with MRSA , GOQ 3 P 3 controls inflammatory responses, accelerates collagen deposition, promotes angiogenesis, and enhances wound closure in the wound healing cascade reaction. This study provides a feasible strategy for constructing dressings targeting chronic infection wounds caused by drug-resistant bacteria.

[Display omitted] • The NIR-responsive of Mo/Fe@CuO 2 nanozyme was synthesized successfully. • Mo/Fe@CuO 2 nanozyme could achieve H 2 O 2 self-supply and highly efficient peroxidase-like activity by CuO 2 NPs and Mo/Fe CDs. • Mo/Fe@CuO 2 nanozyme possessed strong antibacterial activities under NIR irradiation. • Mo/Fe@CuO 2 nanozyme exhibited excellent photodynamic performance, and photostability during NIR irradiation. Nanozymes have drawn increasing attention due to unique enzyme-mimic catalytic activities for the treatment of bacterial infections. Herein, a novel tri-metal nanozyme for synergistic eradication of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was generated by Mo/Fe doped carbon dots (Mo/Fe-CDs) wrapping copper peroxide (CuO 2) nanozyme (Mo/Fe@CuO 2). Mo/Fe@CuO 2 showed near-infrared (NIR) light-enhanced peroxidase-like catalytic activity, and H 2 O 2 self-supply to promote the generation of reactive oxygen species (ROS) for highly efficient antibacterial photothermal therapy. The CuO 2 could generate H 2 O 2 in the acidic microenvironment, and Mo/Fe-CDs consequently could convert H 2 O 2 to hydroxyl radicals (·OH), resulting in the improvement of sterilization efficiency. Interestingly, Mo/Fe-CDs could activate the transformation of Cu2+ to Cu+ through the co-catalytic reaction based on the Mo4+/Mo6+ and Fe3+/Fe2+ redox couples, and provided photonic hyperthermia (PTT) to enhance the peroxidase-like activity. Meanwhile, Mo/Fe@CuO 2 showed glutathione (GSH) oxidase-like activity, which can achieve the depletion of glutathione (GSH) in bacteria, thus significantly improving the bactericidal effect. The collaborative eradication of bacteria, through innovative metal carbon-based nanozyme technology, provides a powerful and feasible approach to treating bacterial infections that threaten human health. [ABSTRACT FROM AUTHOR]

Antimicrobial packing showed great potential in extending the shelf life of food. However, developing a new biocomposite film with an intelligent and efficient antimicrobial performance is still desirable. Herein, a Fe-MoO x encapsulated with curcumin (Cur) filled chitosan-based composite film (CCF films) was prepared by solvent casting method. The total color differences of the CCF films were less than 30%, and satisfactory surface color, transparency, hydrophobicity, and thermal stability were also obtained. Besides, the UV-light/water/oxygen barrier capability and mechanical properties were enhanced with the incorporation of Cur@Fe-MoO x . Moreover, CCF films showed photothermal performance and thermal-controlled curcumin release ability, which endowed the CCF 0.15 film with excellent antibacterial capability toward E. coli (≥99.95%) and S. aureus (≥99.96%) due to the synergistic antibacterial effect. Fe-MoO x exhibited high cell viability and less than 5% hemolysis even under the concentration of 500 μg mL -1 . Based on those unique characteristics, the CCF 0.15 film was chosen for tangerine preservation. The CCF 0.15 film could prolong the shelf life of tangerine by at least 9 days compared with the unpacking group, and the tangerines could maintain the freshness characteristics over a 24 day storage period. Such thermal-mediated antibacterial film proposed by our work showed promising potential in food packaging.