Excellent Antibacterial Activity Research Articles

Investigating the synergistic antibacterial effects of chlorogenic and p-coumaric acids on Shigella dysenteriae

Chlorogenic acid (CGA) is a well-known plant secondary metabolite exhibiting multiple physiological functions. The present study focused on screening for synergistic antibacterial combinations containing CGA. The combination of CGA and p-coumaric acid (pCA) exhibited remarkably enhanced antibacterial activity compared to that when administering the treatment only. Scanning electron microscopy revealed that a low-dose combination treatment could disrupt the Shigella dysenteriae cell membrane. A comprehensive analysis using nucleic acid and protein leakage assay, conductivity measurements, and biofilm formation inhibition experiments revealed that co-treatment increased the cell permeability and inhibited the biofilm formation substantially. Further, the polyacrylamide protein- and agarose gel-electrophoresis indicated that the proteins and DNA genome of Shigella dysenteriae severely degraded. Finally, the synergistic bactericidal effect was established for fresh-cut tomato preservation. This study demonstrates the remarkable potential of strategically selecting antibacterial agents with maximum synergistic effect and minimum dosage exhibiting excellent antibacterial activity in food preservation.

Designing double-layer smart packaging with sustained-release antibacterial and antioxidant activities for efficient preservation and high-contrast monitoring

In this study, a double-layer intelligent packaging, which is designed by a layer-by-layer casting strategy, is employed for efficient food preservation and high contrast monitoring. Specifically, novel zein/tannic acid (TA) composite colloidal particles (ZTs) were prepared by manipulating the non-covalent interaction between zein and TA using an easy antisolvent method. The stable oregano essential oil (OEO) Pickering emulsion (ZTOEO) with varying concentrations of ZTs (0.1%–1.0%) was successfully prepared. The optimized ZTOEO, containing 0.8% ZTs, was then integrated into the emulsified hydrophobic layer of the konjac glucomannan (Kgm) matrix. Finally, the carrageenan (Car) matrix containing alizarine (Al) as an indicator was added to construct the bilayer structure. The outer Car/Al layer serves as an acid/base responsive indicator layer, while the inner Kgm/ZTOEO layer functions as a high-barrier bacteriostatic layer. The double-layer Kgm/ZTOEO-Car/Al is integrated through intermolecular hydrogen bonding and dehydration condensation. Kgm/ZTOEO-Car/Al exhibits excellent slow-release antibacterial and antioxidant activity, with a sensitive, repeatable and accurate visual response to pH/NH3. The composite film demonstrates good mechanical strength, thermal stability, light blocking, and water vapor and oxygen permeability. The individual inner Kgm/ZTOEO film effectively prolonged the shelf-life and quality of fruits, which the double-layer Kgm/ZTOEO-Car/Al film showed minimal changes in TVB-N (16.65 mg/100 g) even after monitoring and maintaining the shrimp freshness for 48 h. It can be easily processed on a large scale into packaging bags and indicator labels. This packaging is expected to be an eco-friendly, low-cost, bacteriostatic, suitable for applications requiring real-time monitoring and maintenance of fruit/seafood freshness.

Visible light-driven Synergetic antimicrobial activity of Cu2O quantum dots and electrospun PAN/PCL nanofiber matrix

This work reported a successful observation of the synergistic rapid antibacterial activity of the Electrospun PAN/PCL Nanofiber (NF) with Cuprous Oxide -based Quantum Dots (QDs). Our findings reveal that the NF-QDs nanostructure exhibits excellent antibacterial activity that eliminated more than 98% of antimicrobial-resistant bacteria in 30 s under visible light. The characterization including X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), UV–Vis spectrophotometer (UV–Vis), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), Brunauer-Emmet-Teller (BET) analysis exhibits good physicochemical properties of both synthesized quantum dots and nanofiber. A desired hydrophobic NF with an average surface roughness of 219.40 nm and 243.46 nm for NF–Cu2O and NF–Cu2O/TiO2 was achieved with an average diameter of 502.54 nm and 343.02 nm, respectively. The antibacterial activity was tested against antibiotics-resistance strains, Klebsiella pneumoniae and Methicillin-resistant Staphylococcus aureus, as well as non-resistance strains, Escherichia coli and Staphylococcus aureus. Our results indicate the promising potential of NF-QDs as antibacterial fabric to halt antibiotic resistance infections and mitigate outbreaks in various sectors.

Oral Administration of Berberine Hydrochloride Based on Chitosan/Carboxymethyl-β-Cyclodextrin Hydrogel.

In this study, a novel oral formulation of berberine hydrochloride (BBH) hydrogel was successfully synthesized through physical cross-linking using chitosan (CS) and carboxymethyl-β-cyclodextrin (CMCD). The characterization results confirmed the successful synthesis of the CS/CMCD hydrogel and the subsequent loading of BBH into this composite (CS/CMCD/BBH) was effectively accomplished. The BBH was used as a model drug and the resulting hydrogel demonstrated a sustained drug release profile. In addition to its improved solubility and sustained release characteristics, the hydrogel exhibited excellent antibacterial activity against common pathogens such as Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and Candida albicans (C. albicans). Additionally, in vitro studies indicated that the hydrogel was not cytotoxic to NIH3T3 and HaCaT cells, suggesting its safety for biomedical applications. This lack of cytotoxic effects, combined with the mechanical strength, solubility improvements, and antibacterial properties of the hydrogel, positions the CS/CMCD/BBH hydrogel as a promising candidate for the effective oral delivery of BBH. By addressing the solubility and delivery challenges of BBH, this hydrogel offers a viable solution for the oral administration of BBH, with potential applications in various biomedical fields.

Design, synthesis and biological evaluation of amphiphilic benzopyran derivatives as potent antibacterial agents against multidrug-resistant bacteria

Antimicrobial resistance has emerged as a significant threat to global public health. To develop novel, high efficiency antibacterial alternatives to combat multidrug-resistant bacteria, A total of thirty-two novel amphiphilic benzopyran derivatives by mimicking the structure and function of antimicrobial peptides were designed and synthesized. Among them, the most promising compounds 4h and 17e displayed excellent antibacterial activity against Gram-positive bacteria (MICs = 1–4 μg/mL) with weak hemolytic activity and good membrane selectivity. Additionally, compounds 4h and 17e had rapid bactericidal properties, low resistance frequency, good plasma stability, and strong capabilities of inhibiting and eliminating bacterial biofilms. Mechanistic studies revealed that compounds 4h and 17e could effectively disrupt the integrity of bacterial cell membranes, and accompanied by an increase in intracellular reactive oxygen species and the leakage of proteins and DNA, ultimately leading to bacterial death. Notably, compound 4h exhibited comparable in vivo antibacterial potency in a mouse septicemia model infected by Staphylococcus aureus ATCC43300, as compared to vancomycin. These findings indicated that 4h might be a promising antibacterial candidate to combat antimicrobial resistance.

Artificial Bacteriophages for Treating Oral Infectious Disease via Localized Bacterial Capture and Enhanced Catalytic Sterilization.

With the rapid emergence of antibiotic-resistant pathogens, nanomaterial-assisted catalytic sterilization has been well developed to combat pathogenic bacteria by elevating the level of reactive oxygen species including hydroxyl radical (·OH). Although promising, the ultra-short lifetime and limited diffusion distance of ·OH severely limit their practical antibacterial usage. Herein, the rational design and preparation of novel virus-like copper silicate hollow spheres (CSHSs) are reported, as well as their applications as robust artificial bacteriophages for localized bacterial capture and enhanced catalytic sterilization in the treatment of oral infectious diseases. During the whole process of capture and killing, CSHSs can efficiently capture bacteria via shortening the distance between bacteria and CSHSs, produce massive ·OH around bacteria, and further iinducing the admirable effect of bacterial inhibition. By using mucosal infection and periodontitis as typical oral infectious diseases, it is easily found that the bacterial populations around lesions in animals after antibacterial treatment fall sharply, as well as the well-developed nanosystem can decrease the inflammatory reaction and promote the hard or soft tissue repair. Together, the high Fenton-like catalytic activity, strong bacterial affinity, excellent antibacterial activity, and overall safety of the nanoplatform promise its great therapeutic potential for further catalytic bacterial disinfection.

Molecularly engineered chitosan-derived poly(aprotic/protic ionic liquids) double-network hydrogel electrolytes for flexible supercapacitors and wearable strain sensors

Polymeric conductive hydrogels have been highlighted for use in flexible electronics, and there is still a challenge to design and fabricate a high-performance hydrogel electrolyte with integrated and multiple properties, such as sustainability, stretchability and compressibility, ionic conductivity, antibacterial property, strain sensitivity, and low-temperature tolerance. Herein, chitosan (CS) derived poly(aprotic/protic ionic liquids) (CS-PAPILs) are facilely prepared by taking the structural and sustainable features of chitosan and betaine hydrochloride, which are used as a functional component for the fabrication of CS-PAPILs/polyacrylamide (PAM)/LiCl (CS-PAPILs/PAM/LiCl) double-network (DN) hydrogel electrolyte via an in situ polymerization of AM and then a soaking strategy in LiCl aqueous solution. The achieved DN hydrogels exhibit tunable mechanical performance (tensile strength of 70–900 kPa, elastic modulus of 31.5–484 kPa, high compressibility (4450 kPa at 80 % strain), superior low-temperature tolerance (freezing point < -85 °C), anti-dehydration performance, high ionic conductivity at 25/-50 °C (94.8/4.6 mS cm−1), and excellent antibacterial activity. As a proof of concept, an assembled flexible and anti-freezing supercapacitor by the as-prepared DN hydrogel electrolyte demonstrated a high specific capacitance of 108.4F/g (at 2 A/g) and impressive cycling stability over 50,000 cycles at temperature as low as −50 °C. Furthermore, a wearable strain sensor based on the DN hydrogel was also demonstrated, and the sensor can be successfully attached to the human joints to monitor various human motions.

Baicalein-modified chitosan nanofiber membranes with antioxidant and antibacterial activities for chronic wound healing

Diabetic foot ulcers, burns and many other trauma can lead to the formation of skin wounds, which often remain open for a long period of time, seriously affecting the quality of patient's life. Oxidative stress and infection are the main factors affecting the healing of chronic wounds, so it is important to develop dressings with dual antioxidant and antimicrobial properties for wound management. In this study, functionalized chitosan was synthesized by modifying chitosan with antioxidant baicalein to enhance the antimicrobial and antioxidant activities of chitosan. Then the obtained baicalein-modified chitosan was prepared into nanofibrous membranes by electrospinning. The membrane structures were characterized, and the antioxidant and antibacterial activities were evaluated by in vivo and in vitro experiments. The results showed that the prepared wound dressings had excellent antioxidant and antibacterial activities and significantly accelerated the wound process. This study provided a reference for the development of novel dressing materials to promote wound healing.

Studies on chlorophenyl, thiophenyl, and biphenyl clubbed tetrahydro bipyrazole carbaldehydes: Synthesis, antimicrobial and antioxidant activity, SAR study, in-silico pharmacokinetics, toxicity, and molecular modeling

A library of chlorophenyl, thiophenyl, and biphenyl clubbed 3′,4,4′,5-tetrahydro-2′H-[1,3′-bipyrazole]-2′-carbaldehydes was produced via aldolic condensation followed by hetero-cyclization. Synthesized moieties were characterized by IR, 1H, and 13CNMR spectral analysis. The molecular docking was conducted utilizing microbial target proteins, 1JX9, and 5C1P to explore the binding interactions of scaffolds. Analogues 4f, 4l, 4r, and 4x exhibited the best docking score of -10.3 kcal/mol with 1JX9 whereas scaffolds 4l and 4o showed maximum docking of -10.4 and -10.2 kcal/mol with target protein 5C1P. Further, scaffolds 4f, 4I, 4l, 4o, 4 u, and 4v showed excellent (pMIC: 1.92 µM/mL) antibacterial activity against S. aureus, B. subtilis, E. coli, P. aeruginosa whereas; analogues 4c, 4l, 4o, 4r, and 4v exhibited admirable (pMIC: 1.92 µM/mL) antifungal activity against R. oryzae fungal strain. Also, analogues were tested for their radical scavenging ability and 4a, 4 g, 4i, 4p, and 4x exhibited good antioxidant activity with 4i standing out as a propitious scaffold with 93.25 % radical scavenging activity. SAR study revealed that biphenyl, 4‑hydroxy-3‑methoxy phenyl, and thiophenyl moieties on the bipyrazole-carbaldehyde scaffold are accountable for virtuous antibacterial, antifungal, and antioxidant activity, respectively. Further in-silico ADME, pharmacokinetic, and toxicity properties were studied, forecasting less-toxic analogues (300 < LD50 ≤ 5000). These findings collectively underscore the potential of the synthesized compounds, with 4l, 4o, 4v and 4x standing out as particularly promising candidates for further exploration.

A novel biosynthesis of activated carbon manganese oxide nanocomposite and assessment of the biomedical role in fabricated cotton fabric nanocomposite

Ordinary products undergo a transformation to imbue new functional characteristics through the incorporation of nanocomposites into textile fabrics due to their high surface-volume ratio. In the present research, activated carbon (AC) manganese oxide nanocomposite was prepared through the sonochemical method using almond leaves and incorporated into cotton fabric via ultrasonic and dip coating methods to enhance the antibacterial activity. The characterization of the nanocomposite was conducted using various techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy,energy-dispersive X-ray spectroscopy, UV–vis spectroscopy, and photoluminescence spectroscopy. The photo luminescence spectra showed a predominant yellow emission at 572 nm. The AC-Mn3O4 nanocomposite exhibited excellent antibacterial activity against gram-positive and -negative bacteria. Notably, AC-Mn3O4 nanocomposite-loaded cotton fabric showed tremendous activity toward Staphylococcus and Escherichia coli bacteria. The antioxidant evaluation using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay revealed a higher antioxidant activity with a lower IC50 value. In vitro cytotoxicity of AC-Mn3O4 nanocomposite was examined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetazolium bromide (MTT) assay against normal mouse fibroblast cells(NIH3T3 cell line) at different concentrations with an IC50 value of 187.6 μg/ml. These results confirm the simple, nontoxic and eco-friendly protocol for the coating of AC-Mn3O4 nanocomposite on cotton fabric, which could be used as a safer alternative approach in health-care applications.

Guar gum enhanced sustained release and therapy effects of tilmicosin-loaded sodium alginate gelatin nanogels against porcine pleuropneumonia

Actinobacillus pleuropneumoniae is an important pathogen of porcine pleuropneumonia, causing huge economic losses to the global pig industry. In order to effectively treat pleuropneumonia infections, a novel tilmicosin-loaded pH-responsive sodium alginate gelatin nanogels with excellent sustained-release was designed by modifying with guar gum (GG). The nanogels modified with GG had uniform size and smooth surface, and its drug loading capacity was 58.2 ± 1.3 %. The nanogels had good palatability and more excellent antibacterial activity compared to tilmicosin solution. Its release rate was faster at pH = 5.5 release medium than those at pH = 7.4 medium. Compared to tilmicosin sodium alginate gelatin nanogels and tilmicosin solution, the mean residence time (MRT) and area under the drug-time curve (AUC) of tilmicosin nanogels modified with GG was enhanced by 3.74 and 1.47, and 3.53 and 1.60 folds, respectively. The excellent sustained-release, pH responsiveness and enhanced absorption of tilmicosin nanogel modified with GG made it more effective in the treatment of infections than that of tilmicosin solution and tilmicosin nanogels.The GG modified tilmicosin nanogels might be an promising formulation for treatment of porcine pleuropneumonia.

3D-printed multifunctional biomass hydrogel device for controlled photothermal distribution and molecular release

Photothermal therapy based on photothermal conversion has received increasing attention due to its non-invasiveness and low side effects. In this study, a 3D-printed biomass photothermal therapy device was prepared for accurate control of photothermal conversion and molecular release. The prepared black phosphorus nanosheets (BPNSs) showed excellent photothermal performance and antibacterial activity. A temperature-regulated sol-gel reversible system was prepared with konjac glucomannan (KGM), tara gum (TG), BPNSs, and manganese dioxide (MnO2) nanoparticles. The sol-gel transition was attributed to the change of interactions of hydrogen bond, and molecular entanglement. Photothermal conversion films with accurate multi-layer and array structures were prepared by 3D printing using the biomass sol-gel conversion system. The photothermal conversion efficiency was regulated by the concentration of BPNSs and MnO2. Under infrared radiation (808 nm, 1 W/cm2) for 5 min, the temperatures of hydrogel films with a MnO2 concentration of 0, 0.5, and 1 % were raised from 25 to 29.3, 61.8, and 90.8 °C, respectively. The accurate temperature distribution induced the controlled release of small active molecules such as epigallocatechin gallate (EGCG) loaded in hydrogels, which was resulted from the changes in the hydrogel structure and the decrease in adsorption energy between polysaccharide and EGCG at high temperatures. This study provides a biomass 3D-printed multifunctional photothermal therapy device and more understanding of the molecular release during photothermal conversion.

Fabrication and characterization of TPGS-modified chlorogenic acid liposomes and its bioavailability in rats.

Chlorogenic acid (CGA), a polyphenol compound, exhibits excellent anti-oxidative, anti-hypoxic, antibacterial, antiviral, and anti-inflammatory activities, however the bioactivity of it has not been fully utilized in vivo due to its instability and low bioavailability. To address these issues, we prepared and characterized CGA-TPGS-LP, which is a TPGS-modified liposome loaded with CGA. The pharmacokinetics of CGA-TPGS-LP were studied in rats after oral administration. CGA-TPGS-LP was fabricated using a combination of thin film dispersion and ion-driven methods. The liposomes were observed to be uniformly small and spherical in shape. Their membranes were composed of lecithin, cholesterol, and TPGS lipophilic head with a TPGS hydrophilic tail chain coating on its surface. The loading efficiency and encapsulation efficiency were found to be 11.21% and 83.22%, respectively. The physicochemical characterisation demonstrated that the CGA was present in an amorphous form and retained its original structural state within the liposomal formulation. The stability of CGA was significantly improved by fabricating TPGS-LP. CGA-TPGS-LP exhibited good sustained-release properties in both simulated gastric and intestinal fluids. Following oral administration, ten metabolites were identified in rat plasma using UPLC-QTOF-MS. UPLC-QqQ-MS/MS quantitative analysis demonstrated that the oral bioavailability of CGA encapsulated in TPGS-modified liposomes was enhanced by 1.52 times. In addition, the three main metabolites of CGA had higher plasma concentrations and slower degradation rate. These results demonstrate that TPGS-modified liposomes could be a feasible strategy to further enhance the oral bioavailability of CGA, facilitating its clinical use.

Development of superhydrophilic ZnOX/TiO2 with visible light-induced self-cleaning and antibacterial properties

Many studies aimed to improve the antibacterial ability and applicability of antibacterial surface materials by altering their chemical composition and structure. In this study, we successfully prepared a multifunctional ZnOX/TiO2 (0<X ≤ 2) nanocomposites by a sol-gel method, which exhibits visible light responsive self-cleaning, antibacterial adhesion, and antimicrobial properties. In the comparison of the three zinc sources, it was found that the ZnOX/TiO2 prepared with zinc sulfate doping had a water contact angle of only 1.7°, with enhanced hydrophilicity, and exhibited the best photocatalytic activity under visible light, with a removal rate of up to 90.2% of methylene orange (MO). Antibacterial tests revealed the average diameters of the inhibition halos for Escherichia coli and Staphylococcus aureus were 10 and 12 mm, respectively, thereby showing excellent antibacterial activity under visible light. The low photogenerated electron-hole recombination and the high rates of ·OH and ·O2- generation through photo-induced interface charge transfer in ZnOX/TiO2 composite, which is the main reason for enhancing the photocatalytic antibacterial activity under visible light irradiation. Release of Zn2+ species, resulting in significant antibacterial performance even under dark conditions. This study combines doping and surface modification, introduce abundant surface hydroxyl groups to endow the composite material surface with superhydrophilicity, anti-bacterial adhesion, and antibacterial properties that can meet the needs of clean and antibacterial surfaces in medical.

Discovery of quaternized pyridine-thiazole-ruthenium complexes as potent anti-Staphylococcus aureus agents

Quaternization of ruthenium complexes may be a promising strategy for the development of new antibiotics. In response to the increasing bacterial resistance, we integrated the quaternary amine structure into the design of ruthenium complexes and evaluated their antibacterial activity. All the ruthenium complexes showed good antibacterial activity against the tested Staphylococcus aureus (S. aureus). Ru-8 was the most effective antibacterial agent that displayed excellent antibacterial activity against S. aureus (MIC = 0.78–1.56 μg/mL). In vitro experiments showed that all nine ruthenium complexes had low hemolytic toxicity to rabbit erythrocytes. Notably, Ru-8 was found to disrupt bacterial cell membranes, alter their permeability, and induce ROS production in bacteria, all the above leading to the death of bacteria without inducing drug resistance. To further explore the antibacterial activity of Ru-8in vivo, we established a mouse skin wound infection model and a G. mellonella larvae infection model. Ru-8 exhibited significant antibacterial efficacy against S. aureus in vivo and low toxicity to mouse tissues. The Ru-8 showed low toxicity to Raw264.7 cells (mouse monocyte macrophage leukemia cells). This study indicates that the ruthenium complex ruthenium quaternary was a promising strategy for the development of new antibacterial agents.

A 3D bioprinted antibacterial hydrogel dressing of gelatin/sodium alginate loaded with ciprofloxacin hydrochloride.

Skin plays a crucial role in human physiological functions, however, it was vulnerable to bacterial infection which delayed wound healing. Nowadays, designing an individual wound dressing with good biocompatibility and sustaining anti-infection capability for healing of chronic wounds are still challenging. In this study, various concentrations of the ciprofloxacin (CIP) were mixed with gelatine (Gel)/sodium alginate (SA) solution to prepare Gel/SA/CIP (GAC) bioinks, following the fabrication of GAC scaffold by an extrusion 3D bioprinting technology. The results showed that the GAC bioinks had good printability and the printed GAC scaffolds double-crosslinked by EDC/NHS and CaCl2 had rich porous structure with appropriate pore size, which were conducive to drug release and cell growth. It demonstrated that the CIP could be rapidly released by 70% in 5min, which endowed the GAC composite scaffolds with an excellent antibacterial ability. Especially, the antibacterial activities of GAC7.5 against Escherichia coli and Staphylococcus aureus within 24h were even close to 100%, and the inhibition zones were still maintained 14.78±0.40mm and 14.78±0.40mm, respectively, after 24h. Meanwhile, GAC7.5 also demonstrated impressive biocompatibility which can promote the growth and migration of L929 and accelerate wound healing. Overall, the GAC7.5 3D bioprinting scaffold could be used as a potential skin dressing for susceptible wounds with excellent antibacterial activity and good biocompatibility to meet urgent clinical needs.

Synthesis and analysis of multifunctional graphene oxide/Ag2O-PVA/chitosan hybrid polymeric composite for wound healing applications

The requirement for accurate treatments for skin diseases and wounds, generated a rising interest towards multifunctional polymer composites, that are capable of mimicking the natural compositions in human body. Also, electroactive composite films disseminate endogenous electrical stimulations that encourage cell migration and its proliferation at wound site, proposing greater opportunities in upgrading the conventional wound patches. In this work, the composite film made of graphene oxide, Ag2O, PVA and chitosan were developed for wound healing applications, by the solution casting method. The even dispersibility of nanofiller in polymeric matrix was validated from the physicochemical analyses. The increment in roughness of the composite film surface was noted from AFM images. The thermal stability and porous nature of the polymer composite were also verified. A conductivity value of 0.16 × 10−4 Scm−1 was obtained for the film. From MTT assay, it was noted that the films were non-cytotoxic and supported cell adhesion along with cell proliferation of macrophage (RAW 264.7) cells. Moreover, the composite film also demonstrated non-hemolytic activity of <2 %, as well as excellent antibacterial activity towards E. coli and S. aureus. Thus, the obtained results validated that the prepared composite film could be chosen as an innovative candidate for developing state-of-the-art wound dressings.

Maleated epoxidized natural rubber grafted cassava starch/silver composite coating for cloth glove: Preparation and physical properties

The green composite was obtained from maleated epoxidized natural rubber (MENR) latex grafted cassava starch (CS) (MNS) and silver nanoparticles (AgNPs) by using a green route process. The immersion of AgNPs in the MNS matrix was checked with UV–visible spectrometer. The SEM was applied to study the morphology of AgNPs particle. The thermal stability of the MNSAg composite increased with increasing AgNPs. The AgNPs well distributed in the MNS matrix. The silver was used to facilitate the facile and fast preparation and to improve the mechanical strength and thermal stability at 420–450 °C of the MNSAg composites. The MNSAg composite containing AgNPs exhibited excellent antibacterial activities against both Escherichia coli and Staphylococcus aureus. Moreover, it showed the high UV absorption. It was used to coat with cloth gloves. The degree of biodegradation of this sample was about 80–90 % after being buried in soil.

Highly active carbon dots based nanozyme for enhanced cholesterol detection and antibacterial activity

Recently, nanozyme have emerged as promising direction for chemical sensing, biomedicine, environmental monitoring. However, the novel nanozyme with better catalytic activity and specificity is urgently required realized great application performance. Herein, Fe doped carbon dots (Cit-Fe-CDs) with peroxidase (POD) like activity are synthesized by hydrothermal treatment of ferric ammonium citrate. Due to the strong coordination capacity between Fe(Ⅲ) and citric acid, the Cit-Fe-CDs exhibited excellent POD activity. Namely the catalytic constant (Kcat) and catalytic efficiency (Kcat /Km) are determined, which are much higher than previous work. Highly effective colorimetric detection of cholesterol in human serum have been realized by the POD activity of Cit-Fe-CDs. Under optimal conditions, the linear range is determined to be 10 and 100 μM with a detection limit (LOD) of 0.061 μM. The LOD is two orders of magnitude lower than most of the existing analysis method. Since substantial amounts of free radicals are involved in the catalytic cycle of POD activity, excellent antibacterial activity against Methicillin-Resistant Staphylococcus aureus (MRSA) should be realized by Cit-Fe-CDs. Notably, about 99.999 % inactivation rate towards MRSA can be realized by 125 μg/mL Cit-Fe-CDs, which showcases promising prospects in addressing bacterial resistance concerns. And we have confirmed that the antibacterials mechanism is related to the generation of hydroxyl radicals by the excellent POD activity of Cit-Fe-CDs.

Development and characterization of multifunctional fish gelatin composite films reinforced with ε‐polylysine and zinc oxide nanoparticles

AbstractActive compounds were usually incorporated into biopolymer films to enhance their properties. The tensile strength (TS) and elongation at break (EAB) of the gelatin composite films increased along with the addition of ε‐polylysine (ε‐PL) and zinc oxide nanoparticles (nano‐ZnO). When the concentrations of ε‐PL and nano‐ZnO were 4% and 0.5%, TS and EAB reached to the maximum which were 53.98 ± 2.61 MPa and 16.05 ± 1.76%. The water vapor permeability, water solubility, and water content of the composite films decreased from 2.01 ± 0.04 10−10 g m−1 Pa−1 s−1 to 1.56 ± 0.07 × 10−10 g m−1 Pa−1 s−1, from 45.23 ± 1.54% to 31.39 ± 1.24% and from 23.89 ± 1.41% to 17.34 ± 2.61%, respectively, compared with gelatin film. The light barrier capacity of the composite film was improved. The surface of the film was relatively smooth, and the cross‐section was overall flat. FTIR results indicated that no chemical reaction occurred among ε‐PL, nano‐ZnO and gelatin. The chemical structure of the films remained unchanged throughout the heat‐sealing process. Moreover, the gelatin films containing ε‐PL and nano‐ZnO showed excellent antibacterial activity. Our findings suggest that the gelatin composite films with antibacterial property hold promise for the application in food packaging materials.