Superior Antibacterial Effect Research Articles

Phytocure drug alternatives to manage antimicrobial resistance in poultry transmitted human pathogens

ABSTRACT This research aimed to explore natural, cost-effective alternatives to conventional antibiotics, focusing on Citrus sinensis peel and Moringa oleifera leaf extracts. The objectives were to extract, characterize, and evaluate the antimicrobial potential of these extracts against common poultry pathogens. The proximate analysis of M. oleifera leaf powder revealed 22% protein, 10% fat, 10% ash, and 10% fiber. Phytochemical screening of both aqueous and ethanol extracts of M. oleifera and orange peel indicated the presence of alkaloids, flavonoids, saponins, tannins, and total phenolics. These extracts exhibited significant antimicrobial activity against bacterial strains like E. coli, S. gallinarum, P. aeruginosa, B. cereus, Campylobacter, S. aureus and M. gallisepticum. In a study involving 30 broilers, those treated with M. oleifera extract showed superior antibacterial effects compared to other treatment groups. These findings suggest that M. oleifera leaf extract could serve as an effective, affordable alternative to antibiotics in broiler diets, potentially improving disease management in the poultry industry.

Mechanisms of slow-release antibacterial properties in chitosan‑titanium dioxide stabilized perilla essential oil Pickering emulsions: Focusing on oil-water interfacial behaviors

Perilla essential oil (PLEO) offers benefits for food preservation and healthcare, yet its instability restricts its applications. In this study, chitosan (CS) and TiO2 used to prepare composite particles. TiO2, after being modified with sodium laurate (SL), was successfully introduced at 0.1 %–3 % into the CS matrix. The resulting CS-SL-TiO2 composite particles can be formed by intertwining and rearranging through intramolecular and intermolecular interactions, and form an O/W interface with stability and viscoelasticity. The Pickering emulsions stabilized by these particles exhibit non-Newtonian pseudoplastic behavior, shear-thinning properties, and slow-release characteristics, along with antibacterial activity. Emulsions with 0.5 % and 1 % CS-SL-TiO2 composites demonstrated superior antibacterial effects against Escherichia coli and Staphylococcus aureus. The study revealed that all emulsions undergo Fickian diffusion and a sustained release of PLEO, with the Ritger-Peppas model best describing this release mechanism. The slow-release behaviors positively correlates with interfacial pressure, composite particle size, composite particle potential, composite contact angle, emulsion particle size and emulsion potential, but negatively correlates with diffusion rate, penetration rate, release kinetics and release rate. The findings lay groundwork for developing slow-release antimicrobial emulsions within polysaccharide matrices, showcasing promise for antimicrobial packaging solutions and enhanced food preservation techniques.

Enhancing plant fiber antibacterial and antiviral performance through synergistic action of amino and sulfonic acid groups

As the most abundant renewable resource, cellulose fibers are potential candidates for use in health-protective clothing. Herein, we demonstrate a novel strategy for preparing cellulose fiber with prominent antibacterial and antiviral performance by the synergistic effect of amino groups and sulfonic acid groups. Specifically, guanylated chitosan oligosaccharide (GCOS) and N-sulfopropyl chitosan oligosaccharide (SCOS) were synthesized and chemically grafted onto cellulose fibers (CFs) to endow the fibers with antibacterial and antiviral properties. Moreover, a compounding strategy was applied to make the fibers with simultaneously high antibacterial and antiviral activity, especially in short contact time. The bacteriostatic rate (against S. aureus: 95.81 %, against E. coli: 92.07 %, 1 h) of the compounded fibers improved substantially when a few GCOS-CFs were mixed with SCOS-CFs; especially, it was much higher than both the individual GCOS-CFs and SCOS-CFs. By contrast, the improvement of the antiviral properties was less dramatic; however, even a few SCOS-CFs was mixed, the antiviral properties increased pronouncedly. Although the electrostatic interaction between SCOS and GCOS can make the SCOS-GCOS mixture lose some extent of antibacterial activity, the long chains of cellulose restrain the electrostatic interaction between sulfonic and amino groups, leading to their synergistic action and eventually superior antibacterial and antiviral effects.

Preparation of Luvangetin Nanoemulsions: Antimicrobial Mechanism and Role in Infected Wound Healing.

Incorporation of luvangetin in nanoemulsions for antimicrobial and therapeutic use in infected wound healing. Luvangetin nanoemulsions were prepared by high-speed shear method and characterized based on their appearance structure, average droplet size, polydispersity index (PDI), electric potential, storage stability. Optimized formulation of luvangetin nanoemulsion by Box-Behnken design (BBD). The antimicrobial activity and antimicrobial mechanism of luvangetin nanoemulsions against common hospital pathogens, ie, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), were investigated using luvangetin nanoemulsions. The biosafety of luvangetin nanoemulsion was evaluated through cytotoxicity, apoptosis, and reactive oxygen species (ROS) assay experiments using human normal epidermal cells and endothelial cells. Finally, the effect of luvangetin nanoemulsion on healing of infected wounds was investigated in B6 mice. Luvangetin nanoemulsion formulation consists of 2.5% sunflower seed oil, 10% emulsifier Span-20 and 7 minutes of shear time, and with good stability. Luvangetin nanoemulsion produces antibacterial activity against S. aureus and E. coli by disrupting the structure of bacterial cell membranes. Luvangetin nanoemulsion are biologically safe for HaCat and HUVEC. Luvangetin nanoemulsion showed good therapeutic effect on MRSA infected wounds in mice. For the first time, developed a new formulation called luvangetin nanoemulsion, which exhibited superior antibacterial effects against Gram-positive bacteria. Luvangetin nanoemulsion has a favorable effect in promoting infected wound healing. We have combined luvangetin, which has multiple activities, with nanoemulsions to provide a new topical fungicidal formulation, and have comprehensively evaluated its effectiveness and safety, opening up new possibilities for further applications of luvangetin.

The high-throughput solid-phase extraction of cis-cyclo(L-Leu-L-Pro) and cis-cyclo(L-Phe-L-Pro) from Lactobacillus plantarum demonstrates efficacy against multidrug-resistant bacteria and influenza A (H3N2) virus.

Introduction: 2,5-diketopiperazines are the simplest forms of cyclic dipeptides (CDPs) and have diverse frameworks with chiral side chains that are useful for drug development. Previous research has investigated the antimicrobial properties of proline-linked CDPs and their combinations in the culture filtrate (CF) of Lactobacillus plantarum LBP-K10 using anion exchange chromatography (AEC). However, the quantity of CDPs showcasing notable anti-influenza virus activity derived from AECs was generally lower than those originating from Lactobacillus CF. Methods: To address this issue, the study aims to propose a more efficient method for isolating CDPs and to introduce the antiviral combinations of CDPs obtained using a new method. The study employed a novel technique entailing high-throughput C18-based solid-phase extraction with a methanol gradient (MeSPE). The MeSPE method involved increasing the methanol concentration from 5% to 50% in 5% increments. Results: The methanol SPE fractions (MeSPEfs) eluted with methanol concentrations between 35% and 45% evinced substantial efficacy in inhibiting the influenza A/H3N2 virus via plaque-forming assay. MeSPEf-45, the 45% MeSPEf, exhibited exceptional efficacy in preventing viral infections in Madin-Darby kidney cells, surpassing both individual CDPs and the entire set of MeSPEfs. To identify the specific antiviral components of MeSPEf-45, all MeSPEfs were further fractionated through preparative high-performance liquid chromatography (prep-HPLC). MeSPEf-45 fractions S8 and S11 presented the highest activity against multidrug-resistant bacteria and influenza A/H3N2 virus among all MeSPEfs, with 11 common fractions. Antiviral fractions S8 and S11 were identified as proline-based CDPs, specifically cis-cyclo(L-Leu-L-Pro) and cis-cyclo(L-Phe-L-Pro), using gas chromatography-mass spectrometry. The combination of MeSPEf-45 fractions S8 and S11 displayed superior antibacterial and anti-influenza virus effects compared to the individual fractions S8 and S11. Discussion: High-throughput MeSPE-derived MeSPEfs and subsequent HPLC-fractionated fractions presents an innovative approach to selectively purify large amounts of potent antimicrobial CDPs from bacterial CF. The findings also show the effectiveness of physiologically bioactive combinations that utilize fractions not containing CDP. This study provides the initial evidence demonstrating the antimicrobial properties of CDPs acquired through high-throughput SPE techniques.

Lack of the IFN-γ signal leads to lethal Orientia tsutsugamushi infection in mice with skin eschar lesions.

Scrub typhus is an acute febrile disease due to Orientia tsutsugamushi (Ot) infection and can be life-threatening with organ failure, hemorrhage, and fatality. Yet, little is known as to how the host reacts to Ot bacteria at early stages of infection; no reports have addressed the functional roles of type I versus type II interferon (IFN) responses in scrub typhus. In this study, we used comprehensive intradermal (i.d.) inoculation models and two clinically predominant Ot strains (Karp and Gilliam) to uncover early immune events. Karp infection induced sequential expression of Ifnb and Ifng in inflamed skin and draining lymph nodes at days 1 and 3 post-infection. Using double Ifnar1-/-Ifngr1-/- and Stat1-/- mice, we found that deficiency in IFN/STAT1 signaling resulted in lethal infection with profound pathology and skin eschar lesions, which resembled to human scrub typhus. Further analyses demonstrated that deficiency in IFN-γ, but not IFN-I, resulted in impaired NK cell and macrophage activation and uncontrolled bacterial growth and dissemination, leading to metabolic dysregulation, excessive inflammatory cell infiltration, and exacerbated tissue damage. NK cells were found to be the major cellular source of innate IFN-γ, contributing to the initial Ot control in the draining lymph nodes. In vitro studies with dendritic cell cultures revealed a superior antibacterial effect offered by IFN-γ than IFN-β. Comparative in vivo studies with Karp- and Gilliam-infection revealed a crucial role of IFN-γ signaling in protection against progression of eschar lesions and Ot infection lethality. Additionally, our i.d. mouse models of lethal infection with eschar lesions are promising tools for immunological study and vaccine development for scrub typhus.

Antibacterial and anti-inflammatory polyethyleneimine/polyacrylic acid hydrogel loaded with CeO2 quantum dots for wet tissue wound dressings

Searching for an antibacterial and anti-inflammatory dressing that can stably adhere to wet tissues remains a momentous clinical challenge, especially in the context of treatment failure due to multi-drug-resistant bacteria. Using a hard template method in combination with an in situ chelating strategy, three-dimensional nitrogen-doped graded porous carbon anchored 1.5–2.5 nm CeO2 quantum dots (CeO2-QDs) were tailor-designed in this study. Using the size effect, CeO2-QDs have a higher percentage of Ce3+ and oxygen vacancies that could amplify their antibacterial effects. Polyethyleneimine/polyacrylic acid (PEA) powder could self-gel and be adhesive due to its strong physical interactions, which make it an ideal carrier for CeO2-QDs. PEA@50 (mg/mL) CeO2-QDs hydrogel and PEA@75 (mg/mL) CeO2-QDs hydrogel with moderate doses of CeO2-QDs show a superior antibacterial effect against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) strains. Furthermore, PEA@50CeO2-QDs hydrogels possess excellent anti-inflammatory capacity through their antioxidant activity, which could promote macrophage M2 phenotype polarization. More importantly, cytotoxicity assays on L929 fibroblasts show that PEA@CeO2-QDs hydrogels have no significant toxicity, and a significant proliferative effect could be observed. Overall, PEA@50CeO2-QDs hydrogels have the potential to become a multifunctional wet tissue dressing with anti-inflammatory and antiseptic properties to promote the healing of infected wounds.

More than the barrier effect: Biodegradable Mg-Ag alloy membranes for guided bone/tissue regeneration

Magnesium (Mg) and its alloys have emerged as promising candidates for guided bone/tissue regeneration (GBR/GTR) due to their good mechanical properties, biosafety, and biodegradability. In this study, we present a pioneering application of Mg-Ag alloys featuring tunable corrosion behaviors for GBR/GTR membranes, showcasing their in vitro antibacterial effects, cell migration, and osteogenic differentiation abilities. Mg-Ag alloys with different Ag contents were engineered to facilitate the cell migration of murine fibroblasts (L929) and the osteogenic differentiation of rat bone mesenchymal stem cells (rBMSCs). The Mg-Ag alloy consisted of recrystallized α-Mg grains and fine Mg4Ag second phases, with an observable refinement in the average grain size to 5.6 µm with increasing Ag content. Among the alloys, Mg-9Ag exhibited optimal mechanical strength and moderate plasticity (tensile yield strength of 205.7 MPa, elongation of 20.3%, and a maximum bending load of 437.2 N). Furthermore, the alloying of Ag accelerated the cathodic reaction of pure Mg, leading to a slightly increased corrosion rate of the Mg-Ag alloys while maintaining acceptable general corrosion. Notably, compared with pure Mg, Mg-Ag alloys had superior antibacterial effects against Porphyromonas gingivalis (P. gingivalis) and Staphylococcus aureus (S. aureus). Taken together, these results provide evidence for the significant clinical potential of Mg-Ag alloys as GBR/GTR membranes.

Efficacy of BioMin F and NovaMin toothpastes against streptococcus mutans: an in vitro study

ObjectiveThis in vitro study was accomplished to demonstrate the antibacterial efficacy of BioMin F and NovaMin toothpastes against the recently-isolated Streptococcus Mutans in comparison with a commonly used fluoride toothpaste.Materials and methodsDental plaque collection method was adopted to isolate streptococcus mutans in children with dental caries. Then an ideal Streptococcus Mutans colony was incubated in 20 Petri dishes that contained Mueller-Hinton medium. Each dish had 3 wells; one well for each toothpaste (BioMin F, NovMin, and Signal) to perform the agar diffusion test. After incubating for 24 hours, the inhabitation zone around each well of each Petri dish was noticed and measured. Statistical Analysis was achieved using a statistical package, SPSS Windows version 17, by applying Kruskal-Wallis with Mann–Whitney U test (α = 0.05).ResultsBioMin F showed the highest mean of inhibition zone diameter (x¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\bar{x}$$\\end{document} = 2.67 mm) in compared with NovaMin and Signal (x¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\bar{x}$$\\end{document} = 0.39 mm and x¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\bar{x}$$\\end{document} = 2.19 mm; p < 0.001 in each pairwise comparison).ConclusionBioMin F toothpaste showed superior antibacterial effect against Streptococcus mutans to Signal and NovaMin toothpastes. Novamin showed the lowest antibacterial effect. This in vitro study suggests that BioMin F toothpaste shows encouraging potential to be recommended as a preventive measure to reduce the caries risk.

Natural Clay-Modified Piezocatalytic Membrane for Efficient Removal of Coliform Bacteria from Wastewater.

In the modern era, water pollution, especially from industries, agricultural farms, and residential areas, is caused by the release of a large scale of heavy metals, organic pollutants, chemicals, etc., into the environment, posing a serious threat to aquatic ecosystems and nature. Moreover, untreated sewage waste discharged directly into nearby water bodies can cause various diseases to mankind due to the high load of fecal coliform bacteria. This work demonstrates the development of a biocompatible, cost-effective, highly robust, efficient, flexible, freestanding, and reusable membrane using naturally formed biocompatible kaolinite clay-doped poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) for effective piezodynamic destruction of coliform bacteria. In this study, Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) have been used to evaluate the mechanical stimulus-responsive antibacterial efficacy of the nanocomposite membrane. The membrane can effectively eradicate nearly 99% viable E. coli and 97% E. faecalis within a span of 40 min under mechanical stimulation (soft ultrasound ∼15 kHz). To further understand the mechanism, an evaluation of reactive oxygen species and bacterial FESEM was performed. These studies revealed that bacterial cells suffered severe visible cell damage after 40 min of piezocatalysis, elucidating the fact that the synthesized membrane is capable of producing a superior piezodynamic antibacterial effect.

Novel Vesicular Formulation Based on a Herbal Extract Loaded with Niosomes and Evaluation of Its Antimicrobial and Anticancer Potential

This study aimed to enhance the anticancer and antibacterial properties of Pistacia atlantica through a new parenteral formulation. The innovative approach involved loading P. atlantica fruit extract onto a novel Pluronic vesicular nano platform (Nio), analyzed using various techniques like GC-Mass, SEM, DLS, and UV-vis. The results revealed a stable, spherical Nio/Extract formulation of 103 ± 4.1 nm, possessing a high zeta potential of −30 ± 2.3 mV, with an impressive encapsulation efficiency of nearly 90 ± 3.5%. This formulation exhibited heightened cytotoxicity against BT-20 and MCF-10 cell lines compared to the extract alone, indicating its potential as a drug carrier with prolonged release characteristics. Additionally, the Nio/Extract demonstrated superior antibacterial effects against Pseudomonas aeruginosa, Staphylococcus epidermidis, and Candida albicans compared to the free extract, showcasing MIC values of 211, 147, and 187 ug/mL, respectively, versus 880, 920, and 960 ug/mL for the pathogens. These findings highlight the potential of niosomal nano-carriers housing P. atlantica extract as a viable therapeutic strategy for combating both malignancies and microbial infections.

Strong infiltrative HHC36 antimicrobial peptide/silver nanoparticles-loaded carboxymethyl chitosan/sodium alginate hydrogel for acne vulgaris therapy

Acne is a common chronic skin inflammatory disease closely related to Cutibacterium acnes (C. acnes), which affects the life quality of patients worldwide, especially adolescents and young adults. However, the physical barrier of the skin makes drugs difficult to infiltrate effectively into infected site, causing acne hard to cure and easy to recur. Herein, we developed an antibacterial skin dressing with strong infiltration of antibacterial agents which can co-delivery small-molecular antimicrobial agents through stratum corneum deeply into dermis, achieving high antimicrobial efficacy. The antibacterial dressings were constructed with carboxymethyl chitosan/sodium alginate (CMCS/SA) hydrogel loading with HHC36 (an antimicrobial peptide) and silver nanoparticles (AgNPs) conjugates (Ag–H2/CMCS/SA hydrogel). The released Ag–H2 from Ag–H2/CMCS/SA hydrogel can early infiltrate into dermis, co-delivery HHC36 and AgNPs due to the infiltration and targeting of HHC36, presenting the superior antibacterial effect compared to HHC36 or AgNPs alone and killing 100% C. acnes and 100% Staphylococcus epidermidis (S. epidermidis) at a very low concentration of Ag–H2 (15 μg ml−1 A g with 7.1 μg ml−1 HHC36). Meanwhile, Ag–H2/CMCS/SA hydrogel was biocompatible due to the natural polysaccharides carboxymethyl chitosan and sodium alginate. The HaCaT cells spread well in Ag–H2/CMCS/SA hydrogel. These results indicate that the co-delivery small-molecular antimicrobial agents is a promising strategy and Ag–H2/CMCS/SA hydrogel has a great potential in the therapy of acne.

Multifunctional nanozyme-reinforced copper-coordination polymer nanoparticles for drug-resistance bacteria extinction and diabetic wound healing

BackgroundDrug-resistant bacterial infections in chronic wounds are a persistent issue, as they are resistant to antibiotics and can cause excessive inflammation due to generation of reactive oxygen species (ROS). An effective solution would be to not only combat bacterial infections but also scavenge ROS to relieve inflammation at the wound site. Scaffolds with antioxidant properties are attractive for their ability to scavenge ROS, and there is medical demand in developing antioxidant enzyme-mimicking nanomaterials for wound healing.MethodsIn this study, we fabricated copper-coordination polymer nanoparticles (Cu-CPNs) through a self-assembly process. Furthermore, ε-polylysine (EPL), an antibacterial and cationic polymer, was integrated into the Cu-CPNs structure through a simple one-pot self-assembly process without sacrificing the glutathione peroxidase (GPx) and superoxide dismutase (SOD)-mimicking activity of Cu-CPNs.ResultsThe resulting Cu-CPNs exhibit excellent antioxidant propertiesin mimicking the activity of glutathione peroxidase and superoxide dismutase and allowing them to effectively scavenge harmful ROS produced in wound sites. The in vitro experiments showed that the resulting Cu-CPNs@EPL complex have superior antioxidant properties and antibacterial effects. Bacterial metabolic analysis revealed that the complex mainly affects the cell membrane integrity and nucleic acid synthesis that leads to bacterial death.ConclusionsThe Cu-CPNs@EPL complex has impressive antioxidant properties and antibacterial effects, making it a promising solution for treating drug-resistant bacterial infections in chronic wounds. The complex’s ability to neutralize multiple ROS and reduce ROS-induced inflammation can help relieve inflammation at the wound site.Graphical Schematic illustration of the ROS scavenging and bacteriostatic function induced by Cu-CPNs@EPL nanozyme in the treatment of MRSA-infected wounds.

Bis-quaternary ammonium betulin-based dimethacrylate: synthesis, characterization, and application in dental restorative resins

Bis-quaternary ammonium betulin-based dimethacrylate derivatives (Bis-QADM-Bet) were synthesized. Regulating the alkyl chain length of Bis-QADM-Bet endows dental resins with superior antibacterial effects and acceptable physicochemical properties.

Droplet-based energy harvesting superhydrophobic membrane with bacterial sensing ability for continuous monitoring

Among the polymeric membranes used in various fields, antibacterial membranes are notable due to their direct relation to health and function issues. Therefore, the physical/chemical stability and long-term antibacterial effects of such membranes are significant for their applications. However, the antibacterial membranes could be inevitably contaminated due to continuous usage and membrane damage, which would be significantly detrimental to human health. Herein, a polysilsesquioxane (PSQ)-based superhydrophobic smart membrane with antibacterial and bacterial sensing ability is introduced that can applied to various types of membrane. The PSQ membrane has superior antibacterial effect via contact-killing/repulsion due to quaternary ammonium and long alkyl chains on surfaces, and has the additional function of water-droplet based energy harvesting. The harvested energy is utilized as for sensing, and the membrane sensor is able to continuously monitor the damage level of the membrane and the degree of bacterial contamination. Hence, this droplet-based energy harvesting superhydrophobic membrane (DESm) is expected to prevent any infection that could otherwise arise due to membrane contamination during daily use.

Butelase 1-Mediated Enzymatic Cyclization of Antimicrobial Peptides: Improvements on Stability and Bioactivity.

Antimicrobial peptides (AMPs) have broad-spectrum antibacterial properties and safety as food preservatives, whereas the stability and antibacterial activity require improvement. Here, the "head-to-tail" cyclization of linear AMP GKE was catalyzed by butelase 1, which resulted in an improved pronouncedly antibacterial effect. Cell morphology and propidium iodide uptake revealed that the increased membrane permeability was one of the bacteriostatic mechanisms of GKE and could be enhanced after cyclization. As cyclic GKE (cGKE) exhibited more stability than the linear counterpart under the microorganism culture environment, the increase in effective bacteriostatic concentration should be a reason for the superior antibacterial effect. Moreover, cGKE exhibited the ordered secondary structure, while GKE possessed a similar structure only in sodium dodecyl sulfate micelles. The structure was also beneficial to improve the antibacterial activity caused by the increased affinity of cGKE to the membranes. Overall, butelase 1-mediated cyclization is a promising strategy for enhancing the antibacterial activity of linear AMPs.

Gold Nanorod-Incorporated Halloysite Nanotubes Functionalized with Antibody for Superior Antibacterial Photothermal Treatment.

The global spread of antibiotic-resistant strains, and the need to protect the microflora from non-specific antibiotics require more effective and selective alternatives. In this work, we demonstrate for the first time a superior antibacterial photothermal effect of plasmonic gold nanorods (AuNRs) via their incorporation onto natural clay halloysite nanotubes (HNTs), which were functionalized with anti-E. coli antibodies (Ab-HNTs). AuNRs were incorporated onto the Ab-HNTs through a facile freeze–thaw cycle, and antibody integrity following the incorporation was confirmed via infrared spectroscopy and fluorescence immunolabeling. The incorporation efficiency was studied using UV-Vis absorption and transmission electron microscopy (TEM). Mixtures of E. coli and AuNR-Ab-HNTs hybrids or free AuNRs were irradiated with an 808 nm laser at 3–4 W cm−2, and the resulting photothermal antibacterial activity was measured via plate count. The irradiated AuNR-Ab-HNTs hybrids exerted an 8-fold higher antibacterial effect compared to free AuNR under 3.5 W cm−2; whereas the latter induced a 6 °C-higher temperature elevation. No significant antibacterial activity was observed for the AuNR-Ab-HNTs hybrid against non-target bacteria species (Serratia marcescens and Staphylococcus epidermidis). These findings are ascribed to the localization of the photothermal ablation due to the binding of the antibody-functionalized clay to its target bacteria, as supported through TEM imaging. In the future, the HNTs-based selective carriers presented herein could be tailored with other antibacterial nanoparticles or against another microorganism via the facile adjustment of the immobilized antibody.

Keratin-Based Composite Bioactive Films and Their Preservative Effects on Cherry Tomato.

In this study, keratins were extracted from pig nail waste through the reduction method using L-cysteine as a reductant. Curcumin was successively incorporated in a mixed solution including keratin, gelatin, and glycerin to prepare different kinds of keratin/gelatin/glycerin/curcumin composite films. The morphology of the keratin/ gelatin/glycerin/curcumin composite films were examined using scanning electron microscopy. The structures and the molecular interactions between curcumin, keratin, and pectin were examined using Fourier transform infrared spectroscopy and X-ray diffraction, and the thermal properties were determined through thermogravimetric analysis. The tensile strengths of keratin/gelatin/glycerin/curcumin and keratin/gelatin/curcumin composite films are 13.73 and 12.45 MPa, respectively, and their respective elongations at break are 56.7% and 4.6%. In addition, compared with the control group (no film wrapped on the surface of tomato), the ratio of weight loss of the keratin (7.0%)/gelatin (10%)/glycerin (2.0%)/curcumin (1.0%) experimental groups is 8.76 ± 0.2%, and the hardness value of the tomatoes wrapped with composite films is 11.2 ± 0.39 kg/cm3. Finally, the composite films have a superior antibacterial effect against Staphylococcus aureus and Escherichia coli because of the addition of curcumin. As the concentration of curcumin reaches 1.0%, the antibacterial activity effect of the film is significantly improved. The diameter of the inhibition zone of E. coli is (12.16 ± 0.53) mm, and that of S. aureus is (14.532 ± 0.97) mm. The multifunctional keratin/gelatin/glycerin/curcumin bioactive films have great potential application in the food packaging industry.

Dual-modified starch nanoparticles containing aromatic systems with highly efficient encapsulation of curcumin and their antibacterial applications

A series of cinnamic acid (CA)-esterified debranched starch (CDS) containing aromatic systems were prepared and successfully fabricated as nanoparticles to encapsulate curcumin by taking advantage of the additional π-π interactions provided from CA. The CDS nanoparticles (CDS NPs) have good dispersion (polydispersity index of 0.124–0.314) and sizes range of 130–330 nm. The excellent biosafety of CDS NPs was demonstrated by hemolysis, cytotoxicity and mutagenicity assays. Efficient encapsulation (LC = 26.86 %) and sustained release of curcumin were achieved, and the curcumin-encapsulated CDS NPs (CDS-Cur NPs) increased 266-fold water solubility and 2.3–6.5-fold photothermal stability for curcumin, compared to free curcumin. Functional studies showed that CDS-Cur NPs exhibited superior biofilm scavenging ability, with a 2–4.3-fold improvement compared to free curcumin. In addition, CDS-Cur NPs also exhibited far superior antibacterial effects than free curcumin in a bacteriostatic food model of chicken breast. This study not only provides a new scheme for the efficient loading of curcumin, but also provides new ideas for the usage of starch-based materials in antibacterial applications.

Studies on Phytoconstituents, Antioxidant and Antimicrobial Activity of Trachyspermum ammi Seed Oil Extract with Reference to Specific Foodborne Pathogens

Trachyspermum ammi L. is a medicinal plant as a source of many secondary metabolites with potential bioactivities. The most valuable components of oil are used in the food industry as flavouring agents, preservatives, and food additives. The objective of this study is to assess the phytoconstituents of seed essential oil from Eastern Odisha (India), as well as its antibacterial and antioxidant activities. The GC-MS analysis found a total of 14 metabolites (98.70%), with thymol (60.71%) being the most abundant one followed by p-cymene (20.58 %), γ-terpinene (13.38 %) and others (4.03%). The well diffusion assay demonstrated an inhibitory effect against two gram-positive and six gram-negative pathogens with ZOI (Zone of Inhibition) between 17 and 20 mm at same 2 µl of oil. E. coli, Citrobacter koseri, Salmonella typhi, and Klebsiella pneumoniae exhibited the most promising antibacterial activity, with MIC range from 15.62 to 31.25 µg/ml and MBC 31.25 to 62.5 µg/ml, respectively. In addition, Klebsiella pneumoniae DR (drug resistance) had a superior antibacterial effect at the same MIC and MBC value of 7.81 µg/ml compared to standard antibiotic Ciprofloxacin, which acted at 50 µg/ml. The growth reduction assay of oil showed the sub-MIC dose effectively restricted the bacterial growth of 8 tested microorganisms. The DPPH assay reveals that essential oil has similar antioxidant potential compared to ascorbic acid. Thus, the present study demonstrates potential of thymol-rich T. ammi essential oil as an antibacterial agent against foodborne diseases.