Antibacterial Experiments Research Articles

Interspecies interactions mediated by arginine metabolism enhance the stress tolerance of Fusobacterium nucleatum against Bifidobacterium animalis.

Colorectal cancer (CRC) is a common cancer accompanied by microbiome dysbiosis. Exploration of probiotics against oncogenic microorganisms is promising for CRC treatment. Here, differential microorganisms between CRC and healthy control were analyzed. Antibacterial experiments, whole-genome sequencing, and metabolic network reconstruction were combined to reveal the anti-Fusobacterium nucleatum mechanism, which was verified by co-culture assay and mendelian randomization analysis. Sequencing results showed that F. nucleatum was enriched in CRC, yet Bifidobacterium animalis decreased gradually from healthy to CRC. Additionally, F. nucleatum could be inhibited by B. animalis. Whole-genome sequencing of B. animalis showed high phylogenetic similarity with known probiotic strains and highlighted its functions for amino acid and carbohydrate metabolism. Metabolic network reconstruction demonstrated that cross-feeding and specific metabolites (acidic molecules, arginine) had a great influence on the coexistence relationship. Finally, the arginine supplement enhanced the competitive ability of F. nucleatum against B. animalis, and the mendelian randomization and metagenomic sequencing analysis confirmed the positive relationship among F. nucleatum, arginine metabolism, and CRC. Thus, whole-genome sequencing and metabolic network reconstruction are valuable for probiotic mining and patient dietary guidance.IMPORTANCEUsing probiotics to inhibit oncogenic microorganisms (Fusobacterium nucleatum) is promising for colorectal cancer (CRC) treatment. In this study, whole-genome sequencing and metabolic network reconstruction were combined to reveal the anti-F. nucleatum mechanism of Bifidobacterium animalis, which was verified by co-culture assay and mendelian randomization analysis. The result indicated that the arginine supplement enhanced the competitive ability of F. nucleatum, which may be harmful to F. nucleatum-infected CRC patients. B. animalis is a potential probiotic to relieve this dilemma. Thus, using in silico simulation methods based on flux balance analysis, such as genome-scale metabolic reconstruction, provides valuable insights for probiotic mining and dietary guidance for cancer patients.

Reactive Oxygen Species-Responsive Gel-Based Microneedle Patches with Antimicrobial and Immunomodulating Properties for Oral Mucosa Disease Treatment.

Oral ulcer wounds are difficult to heal due to bacterial infections, persistent inflammatory responses, and excessive reactive oxygen species (ROS). Therefore, the elimination of bacteria, removal of ROS, and reduction of inflammation are prerequisites for the treatment of mouth ulcer wounds. In this study, oligomeric proanthocyanidins (OPC) and 3-(aminomethyl)phenylboronic acid-modified hyaluronic acid (HP) were used to form polymer gels through dynamic covalent borate bonds. Minocycline hydrochloride (MH) was then loaded into the polymer gel, and a multifunctional MH/OPC-HP microneedles (MNs) with ROS-responsive properties was prepared using a vacuum method. The MH/OPC-HP MNs can rapidly release MH in a diffusive manner and sustainably release OPC in response to ROS. The gel-based MH/OPC-HP MNs extended the retention of OPC in oral ulcers, leading to prolonged ROS scavenging effects. Cytocompatibility and hemocompatibility tests showed that MH/OPC-HP MNs had good biocompatibility. Antibacterial experiments demonstrated that MNs loaded with MH exhibited excellent antibacterial effects. In vitro experiments indicated that MH/OPC-HP MNs could effectively clear ROS, reduce oxidative stress damage, inhibit M1-type macrophage polarization, and induce M2-type polarization. Furthermore, in vivo experiments revealed that MH/OPC-HP MNs could inhibit pro-inflammatory cytokines, promote neovascularization, accelerate epithelial healing of ulcers, and significantly promote healing in a rat model of oral ulcer wound infection. In summary, MH/OPC-HP MNs hold promise as a therapeutic strategy for enhancing the healing of oral ulcer wounds.

Preparation, characterisation, and application of gelatin/sodium carboxymethyl cellulose/peach gum ternary composite microcapsules for encapsulating sweet orange essential oil.

This study successfully developed a gelatin-sodium carboxymethyl cellulose-peach gum composite microcapsule system using the complex coacervation method. Optimal preparation conditions were determined by turbidity, complex condensate yield and encapsulation efficiency: the ratio of gelatin to sodium carboxymethyl cellulose was 7:1, the ratio of gelatin/sodium carboxymethyl cellulose to peach gum was 4:1, and the pH value was 4.2. The morphology of the system was evaluated using scanning electron microscopy and laser confocal microscopy. Structural properties and viscoelasticity were analyzed through Fourier-transform infrared spectroscopy, Raman spectroscopy, and rheology. Results indicated that adding peach gum enhanced the system's structural stability and solid behavior. Thermogravimetric analysis, differential scanning calorimetry, swelling, release, antioxidant, and antibacterial experiments confirmed that the addition of peach gum increased the thermal decomposition temperature of the microcapsule system to 246 °C, enhanced the sustained release capacity, and improved both the antioxidant effects and antibacterial properties. The highest lipid antioxidant value was 1.1 mg MDA/kg, while the total bacterial count reached a maximum of 5.3 log CFU/g, both of which remained below the threshold of food spoilage, thereby confirming the role of the gelatin-carboxymethyl cellulose sodium-peach gum composite system in meat preservation. The gelatin-sodium carboxymethyl cellulose-peach gum composite system's excellent sustained-release capacity, antioxidant effect, and the antibacterial properties of the gelatin-sodium carboxymethyl cellulose-peach gum composite system could provide a new carrier for the application of active substances in the food sector.

Study of an arginine- and tryptophan-rich antimicrobial peptide in peri-implantitis.

The combination of hydrophilic arginine residues and hydrophobic tryptophan residues is considered to be the first choice for designing short-chain antimicrobial peptides (AMPs) due to their potent antibacterial activity. Based on this, we designed an arginine- and tryptophan-rich short peptide, VR-12. Peri-implantitis is a significant microbial inflammatory disorder characterized by the inflammation of the soft tissues surrounding an implant, which ultimately leads to the progressive resorption of the alveolar bone. This study found through antibacterial experiments, wound healing promotion experiments, and anti-inflammatory experiments that VR-12 inhibited and killed planktonic peri-implantitis-associated bacteria, inhibited biofilm formation, and disrupted mature biofilms. Additionally, VR-12 exhibited good biocompatibility with RAW264.7 cells and human gingival fibroblasts (HGFs) cells, promoting proliferation of both cell types. Moreover, VR-12 induced HGFs migration by promoting expression of migration-related factors, thereby promoting soft tissue healing. VR-12 also acted on lipopolysaccharide (LPS)-induced RAW264.7 cells, exerting excellent anti-inflammatory properties by affecting the secretion/expression of inflammation-related factors/genes. Therefore, VR-12 may be a good option for both warding off and treatmenting peri-implantitis.

Preparation of eco-friendly multifunctional lyocell fabric with flame retardant, antibacterial and UV resistant using glucose-derived NP compounds.

A biomass-based finishing agent (ArCP) rich in nitrogen and phosphorus was synthesized from glucose, arginine and phosphorous acid, which was then used for lyocell fabrics to prepare flame retardant, antibacterial and UV resistant properties lyocell fabrics (ArCP-lyocell). The elemental composition, surface morphology, combustion performance, antibacterial and UV resistant properties for the lyocell fabrics before and after modification were investigated. ArCP-lyocell fabrics showed excellent self-extinguishing properties with a limiting oxygen index (LOI) of 35.1% and maintained an LOI of 30.7% even after 30 laundering cycles (LCs). Antibacterial experiments confirmed the antibacterial effect of ArCP-lyocell against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with 99.9% and 92.8% inhibition rates, respectively. In addition, the modified fabrics exhibited excellent UV resistant properties with a UV production factor (UPF) of up to 184.54, and lower transmittance both UVA and UVB rays under 2%. This study provides a simple and efficient approach for developing eco-friendly multifunctional textiles.

Contribution of Phosphorylation Modification to Stability and Antibacterial Activity of Egg White Protein Nanogels Loaded with Cinnamon Bark Essential Oil.

This study evaluated the potential usage of phosphorylated egg white protein (P-EWP) nanogels fabricated via microwave-induced phosphorylation modification and gel process and further ultrasonic nanometrization as novel delivery systems for cinnamon bark essential oil (CBEO). Compared to EWP-CBEO nanogels without chemical phosphorylation, the obtained P-EWP-CBEO nanogels have shown smaller average hydrodynamic diameter (133.6 nm), relatively uniform size distribution (polydispersity index around 0.265), enhanced negative surface charge (-35.4 mV), and improved stability under the conditions of high temperature (up to 90 °C) and ionic strength (up to 200 mM NaCl). Moreover, P-EWP-CBEO nanogels, with hydrophobic interactions and disulfide bonds as the main intermolecular forces, exhibited a remarkable conformational change in microstructures. In addition, the results of the antibacterial experiments on Escherichia coli, Staphylococcus aureus, and Listeria monocytogenes showed that the MIC values of P-EWP-CBEO nanogels were two times lower than those of EWP-CBEO nanogels and could completely inhibit the growth of pathogenic bacteria within 108 h. Hence, we have suggested that P-EWP-CBEO nanogels are successfully fabricated with improved physicochemical properties as novel potential natural preservatives in the food industry.

Antibacterial and osteogenic gain strategy on titanium surfaces for preventing implant-related infections.

Infection and insufficient osseointegration are the primary factors leading to the failure of titanium-based implants. Surface coating modifications that combine both antibacterial and osteogenic properties are commonly employed strategies. However, the challenge of achieving rapid antibacterial action and consistent osteogenesis with these coatings remains unresolved. In this study, a functional composite coating (PDA/PPy@Cu/Dex) was prepared on titanium surfaces using layer-by-layer self-assembly and electrochemical deposition techniques. The hydroxyl groups grafted by polydopamine's (PDA) self-polymerization and the enhanced conductivity and uniform electric field distribution provided by polypyrrole (PPy) allowed for the even dispersion of copper nanoparticles and dexamethasone (Dex) on the titanium surface. This synergistically coupled the photothermal ion antibacterial properties of copper nanoparticles with the osteogenic promotion of dexamethasone. In vitro antibacterial experiments revealed that the heat generated by photothermal effects and reactive oxygen species enhanced the antibacterial activity of copper ions, reducing the antibacterial time to six h and achieving antibacterial enhancement. In vitro cell experiments showed that the long-term slow release of copper ions and dexamethasone enhanced the osteogenic differentiation of stem cells, thereby achieving osteogenic benefits. Moreover, in vivo toxicity experiments demonstrated that the composite coating had no adverse effects on normal tissues. Therefore, the antibacterial and osteogenic enhancement strategy for titanium surfaces presented in this study offers a new potential approach for preventing implant-associated infections.

The Leaf Essential Oils of Syzygium oblatum and Syzygium abortivum: Chemical Composition, Antimicrobial Activity, and Molecular Docking Study

Background and Objectives Syzygium (the family Myrtaceae) is a well-known genus in the field of food chemistry and medicinal purposes. The current study aims to provide a chemical analysis of essential oils from the fresh leaves of two Vietnamese Syzygium species Syzygium oblatum (Roxb.) Wall. ex Steudel and S. abortivum (Gagnep.) Merr. & L.M.Perry. Methods Chemical compounds in essential oils were identified using GC-FID/MS (gas chromatography-flame ionization detection/mass spectrometry) analysis. The broth microdilution method was used for the antimicrobial assay. Docking stimulation aided experimental results. Results ( E)-Caryophyllene (27.89%), α-selinene (18.34%), β-selinene (17.48%), and α-pinene (5.20%) were identified to be the main compounds in S. oblatum leaf essential oil, whereas the leaf essential oil of S. abortivum was dominated by ( E)-caryophyllene (19.56%), δ-cadinene (11.03%), germacrene D (10.34%), and γ-muurolene (5.50%). It noted that both studied oil samples with the MIC/IC50 values of 8-32 µg/mL/4.56-10.37 µg/mL were comparable to the standard drugs in antimicrobial experiments against the Gram-positive bacteria Bacillus cereus and Enterococcus faecalis, and yeast Candida albicans. Molecular docking results showed that the main compound ( E)-caryophyllene primarily formed hydrophobic interactions with the microbial proteins C. albicans N-myristoyl transferase B. cereus patB1, and E. faecalis carbamate kinase with the binding affinities of −6.969, −6.342, and −5.530 kcal/mol, respectively Conclusion It is advised to isolate the main chemicals and conduct in vivo antibacterial experiments for both essential oils and their main compounds.

3D printing of antimicrobial adsorbents using Mercapto-graphene oxide / chitosan / ε-Polylysine: Elucidating adsorption mechanisms and antimicrobial performance

Cu2+ in wastewater is hazardous to human health, and adsorption technology can effectively remove heavy metal ions. In this study, sulfhydryl graphene oxide/chitosan/ε-polylysine (SGCS-E) polymeric antimicrobial materials were prepared using 3D printing technology. These materials were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and XPS. The effects of temperature and other influencing factors on the adsorption performance were systematically investigated. The adsorption process followed pseudo-second-order kinetics and the Langmuir model. The maximum adsorption capacity of the adsorbent was 313 mg/g at an initial Cu2+ concentration of 20 mg/L, pH 5, and a temperature of 303.15 K. The study on the adsorption mechanism showed that the adsorption of Cu2+ by SGCS-E was mainly controlled by chemical interactions. Antibacterial experiments showed that SGCS-E has a good growth inhibition effect on E. coli and S. aureus. The antibacterial process of SGCS-E is mainly achieved by interfering with the synthesis of proteins and DNA in bacterial cells. Therefore, SGCS-E can not only adsorb and remove Cu2+ from wastewater but also inhibit the overgrowth of microorganisms in the porous adsorbent and improve its reusability, making it a dual-functional adsorbent-antibacterial material with high stability.

Tourmaline nanoparticles applying in chitosan/polyvinyl alcohol fibrous membrane for hemostatic and antibacterial wound dressing

The development of a wound dressing with good hemostatic and antibacterial properties is of great significance for functional wound healing. As possessing the negative charges, mineral tourmaline may be used as an additive to enhance the functionality of wound dressings. In this study, tourmaline/chitosan/polyvinyl alcohol (TM/CS/PVA) fibrous membrane was prepared through electrospinning technology. The addition of tourmaline nanoparticles (TM NPs) improved the mechanical properties, hydrophilicity and swelling properties of fibrous membrane (the swelling ratio was as high as 400 %). 5 %TM/CS/PVA fibrous membrane have a high porosity of 92.18 ± 2.71 %. The cytotoxicity and hemolysis ratio of 5 %TM/CS/PVA fibrous membrane are very low, demonstrating favorable biocompatibility. In vitro coagulation test showed that compared with CS/PVA fibrous membrane, the hemostatic effect of 5 %TM/CS/PVA fibrous membrane (BCI 18.59 ±1.62 %) was increased by 61.17 %. The antibacterial experiment showed that compared with CS/PVA fibrous membrane, the antibacterial activity (percentage inhibition) of fibrous membrane after adding TM NPs increased against E. coli and S. aureus were increased by 3.54 % and 34.27 %, respectively. This kind of fibrous membrane with hemostatic and antibacterial properties has potential application value as functional wound dressings.

Multifunctional Polysaccharide Self-Healing Wound Dressing: NIR-Responsive Carboxymethyl Chitosan / Quercetin Hydrogel.

As the misuse of antibiotics increases bacterial resistance, the treatment of infected wounds caused by bacteria encounters significant challenges. Conventional antimicrobial dressings often fall short in their ability to inhibit bacterial infections while simultaneously promoting wound healing. To address this issue, a polysaccharide self-healing hydrogel (CPP@PDA/Que3) wound dressing is successfully developed by incorporating quercetin and polydopamine nanoparticles into a carboxymethyl chitosan matrix. The dressing can be easily injected locally to create a protective barrier over the wound, effectively stopping bleeding and rapidly inhibiting inflammation. Furthermore, the CPP@PDA/Que3 hydrogel exhibits remarkable antioxidant and antibacterial properties, stemming from the combination of quercetin and near-infrared (NIR) photothermal therapy. It demonstrates the ability to eliminate 99.52% of Staphylococcus aureus and 99.39% of Escherichia coli in in vitro antibacterial experiments. Additionally, the in vivo wound healing experiment shows a healing rate of ≈97%. The experimental results indicate that under NIR laser (808nm) irradiation, the polysaccharide-based hydrogel dressing significantly inhibits bacterial growth, reduces oxidative stress, expedites angiogenesis, and thereby accelerates the transition from inflammation to wound healing. In summary, the CPP@PDA/Que3 hydrogel exhibits significant potential as a wound dressing, providing a novel approach for clinically advancing the treatment of bacterial wounds.

Metabolic Flux Analysis of Xanthomonas oryzae Treated with Bismerthiazol Revealed Glutathione Oxidoreductase in Glutathione Metabolism Serves as an Effective Target.

Bacterial blight (BB) of rice caused by Xanthomonas oryzae pathovar oryzae (Xoo) is a serious global rice disease. Due to increasing bactericide resistance, developing new inhibitors is urgent. Drug repositioning offers a potential strategy to address this issue. In this study, we integrated transcriptional data into a genome-scale metabolic model (GSMM) to screen novel anti-Xoo targets. Two RNA-seq datasets (before and after bismerthiazol treatment) were used to constrain the GSMM and simulate metabolic processes. Metabolic fluxes were calculated using parsimonious flux balance analysis (pFBA) identifying reactions with significant changes for target screening. Glutathione oxidoreductase (GSR) was selected as a potential anti-Xoo target and validated through antibacterial experiments. Virtual screening based on the target identified DB12411 as a lead compound with the potential for new antibacterial agents. This approach demonstrates that integrating metabolic networks and transcriptional data can aid in both understanding antibacterial mechanisms and discovering novel drug targets.

Microneedles based on hyaluronic acid-polyvinyl alcohol with antibacterial, anti-inflammatory, and antioxidant effects promote diabetic wound healing

Diabetic wound healing has become one of the major clinical burdens due to uncontrolled bacterial growth and an increase in the risk of various microbial infections. Despite excellent antioxidant properties, the poor aqueous solubility of resveratrol (RES) hampers its applicability. In this study, we proposed a novel multifunctional microneedle patch loaded with RES-encapsulated polymeric micelles. Resveratrol micelles (RES MC) were loaded in the microneedle tip, while the base part was coated with the antibiotic gentamicin (GEN) to promote wound healing. The microneedle tip composed of sodium hyaluronate (HA) could effectively deliver the anti-inflammatory and antioxidant RES MC. Furthermore, the base of the microneedle patch composed of polyvinyl alcohol (PVA) offered excellent flexibility, releasing GEN and providing resistance to bacterial contamination, thereby further promoting wound repair. In vitro antibacterial experiments indicated that the bactericidal rate reached 99 %. Further, the wound healing rate was recorded as 86.05 % on the 11th day of diabetes wound treatment. Together, the multifunctional microneedle patch with excellent biocompatibility exhibited anti-inflammatory, antioxidant, and antibacterial effects on the wound healing process, potentiating its efficacy in the treatment of diabetic wounds.

Coral-like AgNPs hybrided MOFs modulated with biopolymer polydopamine for synergistic antibacterial and biofilm eradication

Bacterial contamination is an intractable challenge in food safety, environments and biomedicine fields, and places a heavy burden on society. Polydopamine (PDA), a high molecular biopolymer, is considered as a promising candidate to participate in the design of novel antibacterial agents with unique contributions in biocompatibility, adherence, photothermal and metal coordination ability. In this study, coral-like ZIFL-PDA@AgNPs with excellent antibacterial properties and biocompatibility were prepared by embedding AgNPs into the biopolymer PDA-modulated ZIFL-PDA nanostructures by green reduction method to solve the problem with poor stability of AgNPs. Based on the plasma resonance effect of AgNPs, coral-like ZIFL-PDA@AgNPs had enhanced photothermal properties compared with ZIFL-PDA. Due to the synergistic effect between antibacterial metal ions mainly Ag+ and the photothermal effect, coral-like ZIFL-PDA@AgNPs showed enhanced anti-mature biofilm and antibacterial properties, which was dependent on its concentration and sterilization time. In addition, regulated by the ZIFL-PDA nanostructure, coral-like ZIFL-PDA@AgNPs demonstrated a unique Ag+ long-time sustained release behavior, giving it an extended antibacterial validity period and good biocompatibility. Antibacterial mechanism experiments indicated that coral-like ZIFL-PDA@AgNPs can significantly damage the integrity of bacterial cell membrane, reduce the content of ATP in bacterial by affecting the activity of succinate dehydrogenase, and induce the accumulation of reactive oxygen species, ultimately leading to bacterial death.

In-Situ and Green Synthesis of Silk Fibroin-Silver Nanoparticles Composite Microfibers for Enhanced Antibacterial Applications.

The antibacterial properties of modified silk fibroin microfibers (SF MFs) have been widely studied. Among various modifications, integration of silver nanoparticles (Ag NPs) and SF MFs has garnered significant attention due to the broad-spectrum antibacterial activities and long-term antibacterial effect of Ag nanomaterials. However, the traditional introduction of reducing agents or other additives during the synthesis of Ag-SF composite MFs potentially affects their structure and antibacterial properties. Facile, green and effective methods for the preparation of Ag-SF MFs with enhanced antibacterial properties are therefore highly desired. In this study, Ag NPs were uniformly in-situ deposited onto the optimized SF MFs by adjusting the pH and duration conditions under the guidance of green chemistry. The loaded Ag NPs have a good dispersibility and an average size of ~10 nm. The stability of SF MFs after the deposition of Ag NPs and the crystalline features of the loaded Ag NPs have been carefully investigated. Moreover, antibacterial experiments confirmed that Ag-SF MFs exhibited superior antibacterial activities. After co-incubating Ag-SF MFs with L929 cells, the cell viability reached 90 %, demonstrating the great biocompatibility of the modified fibers. This green in-situ synthetic method will promote the further medical use of Ag-SF MFs in antibacterial fields.

Synthesis, Characterizationand Antibacterial Activity Studyof Para-substituted Derivatives of N -benzyl-3-methylbuten-2-enamides.

In order to deeply explorethe effect of para-substituentson the antibacterial activity ofN-benzyl-3-methylbuten-2-enamidederivatives,we elaborately synthesizedthreesuchpara-substituted derivatives(compounda: N-(4-hydroxybenzyl)-3-methylbut 2-enamide;compoundb:N-(4-isobutoxybenzyl)-3-methylbut-2-enamide;compoundc:N-(4-isopropoxybenzyl)-3-methylbut-2-enamide),of which thestructures were determined by ways of single crystal X-ray diffraction data analysis mainly. The antibacterial performance experiments showed thatcompounds a, band cwere evaluated for their antibacterial (Escherichia coli, Staphylococcus aureus,andEnterobacter aerogenes)activities.Among them, compounds a, band chavean effective antibacterial reagents forE.coliexhibiting MIC values of 0.01,0.01 and0.01g/mL, respectively, but inactive for E. aerogenes.In addition, compounds band chave better activity than compounda against S. aureuswithMIC values of 0.01 and0.02g/mL.These results provide an important basis for further study of the antibacterial properties and structure-activity relationship of these compounds, and are expected to provide valuable reference for the development of new antibacterial drugs.

Bimetallic FeCo metal–organic framework based cascade reaction system: Enhanced peroxidase activity for antibacterial performance

Metal-organic frameworks (MOFs), as a peroxidase (POD), can catalyze the conversion of H2O2 to reactive oxygen species (ROS) for antibacterial application. To achieve strong antibacterial activity, it is necessary to improve the enzyme-like activity of MOFs. In this study, FexCoMOF was synthesized by incorporating Co(II) to improve the electron transfer of Fe(III)/Fe(II), which enhanced its redox capacity as a nanozyme and further promoted the generation of hydroxyl radical (⋅OH), exhibiting higher POD activity. Doping with different amounts of Co(II) altered the particle size, specific surface area, and surface defects of FexCoMOF, thus exhibiting differential enzyme-like activities. Additionally, a glucose-responsive enzyme cascade reaction system based on Fe4CoMOF/glucose oxidase (GOx) was established. In the presence of glucose, the in situ-generated substrate H2O2 was in contact with the catalytic site and the generated gluconic acid enabled Fe4CoMOF to maintain maximum enzyme activity under physiological pH conditions, avoiding damage caused by the use of exogenous high concentrations of H2O2. In the in vitro antibacterial experiment, the minimum inhibitory concentration (MIC) of Fe4CoMOF/GOx was 10 μg mL−1 for Escherichia coli (E. coli) and 5 μg mL−1 for Staphylococcus aureus (S. aureus) (∼108 CFU mL−1). The increase in enzyme activity resulted in a considerable reduction in the dose of the antibacterial agent, which was conducive to improving bio-safety. The in vivo experiment in mice demonstrated that the glucose-responsive Fe4CoMOF-based cascade reaction system had excellent antibacterial properties and remarkably promoted wound healing. The antibacterial agent based on bimetallic MOF developed in this work provides a new idea for cascade catalytic antibacterial therapy and will have remarkable application prospects in biomaterials and nanomedicine.

Optimization of White Tea Flavanol Extraction Process by the Ultrasonic‐Assisted Deep Eutectic Solvent Method and Determination of the Antioxidant and Antibacterial Activity

ABSTRACTFlavanols have a variety of health benefits and biological activities and become the hotspot of the food development and research. In this research, flavanols were extracted from white tea by ultrasonic‐assisted deep eutectic solvent (DES) method. High‐performance liquid chromatography was used to determine the content of flavanols. The influence of four factors on the flavanol extraction yield was analyzed by single factor experiments, including deep eutectic solvent mole ratio (the mole of hydrogen bond acceptors: the mole of hydrogen bond donors), solid–liquid ratio (white tea sample weight/g: the volume of DES/mL), extraction time and extraction temperature. On the basis of single factor experiments, the factors which had significant effects on the flavanol extraction yield were further optimized by the response surface test. The results showed that the optimized extraction conditions were as follows: the mole ratio of DES 1: 4 (choline chloride: 1,2‐propanediol), the solid–liquid ratio 1:30, the extraction temperature 56°C, the extraction time 53 min, and the ultrasonic power 341 W. Under the above parameters, the extraction yield of white tea flavanols was 9.63 mg/g. After purification with macroporous resin, antioxidation and antibacterial experiments were carried out. The results showed that the antioxidant and antibacterial effects of white tea flavanols were remarkable. The antibacterial effects performed best on Escherichia coli, followed by Bacillus subtilis and Staphylococcus aureus. The maximum diameter of the antibacterial zone on Escherichia coli was 0.95 ± 0.11 mm. The best radical scavenging rates of OH, ABTS+ and DPPH were 97.1%, 97.5%, and 88.4%, respectively, when the flavanol concentration was 9.5 mg/mL. The conclusions of this research can provide theoretical foundation for the further study of white tea flavanols.

Enhancing antibacterial performance and stability of implant materials through surface modification with polydopamine/silver nanoparticles

Implants and various medical devices possess surfaces that are prone to bacterial colonization due to bacterial adhesion and the formation of biofilms. Therefore, inhibiting bacterial colonization is a crucial strategy for preventing infections. Although there have been reports on antibacterial surfaces, the synthetic processes involved are often complex and labor-intensive, which significantly limits their practical applications. Furthermore, there is a lack of studies investigating the interplay between antibacterial performance and stability. In this study, silver ions were reduced to form silver nanoparticles, which were then loaded onto polydopamine (PDA) particles. The successful assembly of PDA-Ag on the surface of the titanium alloy was confirmed through X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS). The morphologies of the micro- and nanoparticles, as well as the surface morphology after deposition, were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and a 3D optical profilometer. The abrasion experiments conducted on the three surfaces demonstrated that the TC4@PDA–Ag3 surface exhibited superior friction performance compared to the other two surfaces. Antibacterial and antibacterial stability experiments were conducted on this series of surfaces. The results indicated that the adhesion rate of TC4@PDA–Ag3 on Escherichia coli (E. coli) was 99.68 %, while the antibacterial efficiency against Staphylococcus aureus (S. aureus) was 95.97 %. This study presents a novel approach to address the issue of implant surface infections by demonstrating resistance to bacterial adhesion and colonization, specifically against E. coli and S. aureus.

Preparation of Polyvinyl Alcohol–Chitosan Nanocellulose–Biochar Nanosilver Composite Hydrogel and Its Antibacterial Property and Dye Removal Capacity

In this research, silver-loaded biochar (C-Ag) was acquired from a waste fish scale, and nanocellulose (CNF) was prepared from the waste wheat stalk. Then C-Ag was loaded into chitosan-polyvinyl alcohol hydrogel (CTS-PVA) with CNC as a reinforcement agent, and a novel nanocomposite material was acquired, which could be efficiently applied for antibacterial and dye removal. By plate diffusion analysis, the inhibition areas of C-Ag-CTS-PVA-CNF (C/CTS/PVA/CNF) hydrogel against E. coli ATCC25922, S. aureus ATCC6538, and P. aeruginosa ATCC9027 could reach 22.5 mm, 22.0 mm, and 24.0 mm, respectively. It was found that the antibacterial rate was 100% in the water antibacterial experiment for 2 h, and the antibacterial activity was more than 90% within 35 days after preparation, and the antibacterial rate was more than 90% after repeated antibacterial tests for five times. Through swelling, water adsorption, water loss rate, and water content tests, the hydrogel manifested good moisturizing properties and could effectually block the loss of water and improve the stability of the C/CTS/PVA/CNF hydrogel. The pseudo-first-order and pseudo-second-order models were built, and the adsorption capacity of hydrogel to dye was analyzed, and the dye removal was more consistent with the pseudo-first-order kinetic model. The best removal effect for Congo red was 96.3 mg/g. The C/CTS/PVA/CNF hydrogel had a remarkable removal efficacy on Malachite green, Methyl orange, Congo red, and Methylene blue. As a result, the C/CTS/PVA/CNF hydrogels had robust antibacterial properties and reusability. In addition, the present research developed a facile strategy for effectual dyes removal from the aqueous medium.