Strong Antibacterial Effect Research Articles

Sol-gel derived ternary CrxCuCx-1 compounds: Characterization, structural insights and biological properties

This research explores a novel method for synthesizing Cr-Cu-C ternary carbide using a sol-gel technique. The study targeted to produce a wide range of transition metal carbides within the Cr-Cu-C system by varying the elemental ratios. The primary goal was to observe how compositional changes affect the morphological, structural, and chemical properties of the resulting ternary compounds resembling the MAX phase. Another focus is to establish a practical synthesis route and evaluating the materials' suitability for different applications. The synthesis process involved combining metal nitrates and citric acid, followed by carbothermal reduction. Comprehensive characterization techniques, including FTIR, XRD, SEM, EDX, XPS, and Raman spectroscopy, were employed to thoroughly recognize the prepared materials. In XRD, the calculated lattice parameters indicated hexagonal structures for all the prepared ratios, confirming successful synthesis and providing insights into their morphological and chemical properties. This has also been supported with other characterization techniques, Additionally, the Cr-Cu-C materials demonstrated strong antifungal and antibacterial effects against Candida albicans, E. coli, and B. cereus, highlighting their potential for biomedical applications. Furthermore, their anti-cancer potential against HepG2 liver cancer cells was assessed, showing effectiveness and inhibition among the samples. These findings highlight the potential of the synthesized Cr-Cu-C materials in diverse biomedical applications, supported by their structural integrity, morphological features, and antimicrobial properties.

Sustainable synthesis of zinc oxide nanoparticles using Piper betle petiole leaf extract: Antibacterial, antioxidant, and cytotoxic potential

The present study used Piper betle petiole leaf extract as an efficient reducing agent to produce zinc oxide nanoparticles (ZnO NPs). The change in the color of reaction mixture from brown to white indicates the formation of ZnO NPs, which is also noticed in UV–Visible spectral analysis (peak at 320 nm). Investigations using X-ray diffraction (XRD) revealed that the particles were crystalline. Additionally, scanning electron microscopy (SEM), Energy Dispersive X-ray diffraction (EDAX), dynamic light scattering (DLS), and Fourier transform infrared (FTIR) techniques were used to understand the structural, and elemental aspects of the as-prepared ZnO NPs. The antibacterial activity of ZnO NPs was assessed using the disc diffusion approach method against clinical strains of Escherichia coli, Pseudomonas fluorescence, Micrococcus luteus, and Bacillus subtilis. The zone of inhibition and minimum inhibitory indices (MIC) were used in this process. The as-prepared ZnO NPs showed strong antibacterial effects. In addition, the anticancer efficacy of the material was tested against MDA-MB-231 breast cancer cell lines, the results of which revealed that the tested ZnO NPs was potent in inhibiting the growth of the cancer cells. The mechanistic evaluation of such an activity carried out using in silico methods suggested that the anti-breast cancer activity of L-ZnONPs was mediated by human HER2 kinase domain. This suggests that preparation of ZnO NPs from plant sources can be an excellent method of producing biomedical goods that are both environmentally friendly and versatile.

Effect and mechanism of Qingre Huashi decoction on drug-resistant Helicobacter pylori.

Helicobacter pylori (HP), the most common pathogenic microorganism in the stomach, can induce inflammatory reactions in the gastric mucosa, causing chronic gastritis and even gastric cancer. HP infection affects over 4.4 billion people globally, with a worldwide infection rate of up to 50%. The multidrug resistance of HP poses a serious challenge to eradication. It has been de-monstrated that compared to bismuth quadruple therapy, Qingre Huashi decoction (QHD) combined with triple therapy exhibits comparable eradication rates but with a lower incidence of adverse reactions; in addition, QHD can directly inhibit and kill HP in vitro. To explore the effect and mechanism of QHD on clinically multidrug-resistant and strong biofilm-forming HP. In this study, 12 HP strains were isolated in vitro after biopsy during gastroscopy of HP-infected patients. In vitro, the minimum inhibitory concentration (MIC) values for clinical HP strains and biofilm quantification were determined through the E-test method and crystal violet staining, respectively. The most robust biofilm-forming strain of HP was selected, and QHD was evaluated for its inhibitory and bactericidal effects on the strain with strong biofilm formation. This assessment was performed using agar dilution, E-test, killing dynamics, and transmission electron microscopy (TEM). The study also explored the impact of QHD on antibiotic resistance in these HP strains with strong biofilm formation. Crystalline violet method, scanning electron microscopy, laser confocal scanning microscopy, and (p)ppGpp chromatographic identification were employed to evaluate the effect of QHD on biofilm in strong biofilm-forming HP strains. The effect of QHD on biofilm and efflux pump-related gene expression was evaluated by quantitative polymerase chain reaction. Non-targeted metabolomics with UHPLC-MS/MS was used to identify potential metabolic pathways and biomarkers which were different between the NC and QHD groups. HP could form biofilms of different degrees in vitro, and the intensity of formation was associated with the drug resistance of the strain. QHD had strong bacteriostatic and bactericidal effects on HP, with MICs of 32-64 mg/mL. QHD could inhibit the biofilm formation of the strong biofilm-forming HP strains, disrupt the biofilm structure, lower the accumulation of (p)ppGpp, decrease the expression of biofilm-related genes including LuxS, Spot, glup (HP1174), NapA, and CagE, and reduce the expression of efflux pump-related genes such as HP0605, HP0971, HP1327, and HP1489. Based on metabolomic analysis, QHD induced oxidative stress in HP, enhanced metabolism, and potentially inhibited relevant signaling pathways by upregulating adenosine monophosphate (AMP), thereby affecting HP growth, metabolism, and protein synthesis. QHD exerts bacteriostatic and bactericidal effects on HP, and reduces HP drug resistance by inhibiting HP biofilm formation, destroying its biofilm structure, inhibiting the expression of biofilm-related genes and efflux pump-related genes, enhancing HP metabolism, and activating AMP in HP.

Investigating the Effectiveness of Ceragenins against Acinetobacter baumannii to Develop New Antimicrobial and Anti-Adhesive Strategies.

A growing body of experimental data indicates that ceragenins (CSAs), which mimic the physicochemical properties of the host's cationic antimicrobial peptide, hold promise for the development of a new group of broad-spectrum antimicrobials. Here, using a set of in vivo experiments, we assessed the potential of ceragenins in the eradication of an important etiological agent of nosocomial infections, Acinetobacter baumannii. Assessment of the bactericidal effect of ceragenins CSA-13, CSA-44, and CSA-131 on clinical isolates of A. baumannii (n = 65) and their effectiveness against bacterial cells embedded in the biofilm matrix after biofilm growth on abiotic surfaces showed a strong bactericidal effect of the tested molecules regardless of bacterial growth pattern. AFM assessment of bacterial cell topography, bacterial cell stiffness, and adhesion showed significant membrane breakdown and rheological changes, indicating the ability of ceragenins to target surface structures of A. baumannii cells. In the cell culture of A549 lung epithelial cells, ceragenin CSA-13 had the ability to inhibit bacterial adhesion to host cells, suggesting that it interferes with the mechanism of bacterial cell invasion. These findings highlight the potential of ceragenins as therapeutic agents in the development of antimicrobial strategies against bacterial infections caused by A. baumannii.

An organometallic hybrid antibiotic of metronidazole with a Gold(I) N-Heterocyclic Carbene overcomes metronidazole resistance in Clostridioides difficile

Antimicrobial resistance (AMR) has been emerging as a major global health threat and calls for the development of novel drug candidates. Metal complexes have been demonstrating high efficiency as antibacterial agents that differ substantially from the established types of antibiotics in their chemical structures and their mechanism of action. One strategy to exploit this potential is the design of metal-based hybrid organometallics that consist of an established antibiotic and a metal-based warhead that contributes an additional mechanism of action different from that of the parent antibiotic. In this communication, we describe the organometallic hybrid antibiotic 2c, in which the drug metronidazole is connected to a gold(I) N-heterocyclic carbene warhead that inhibits bacterial thioredoxin reductase (TrxR). Metronidazole can be used for the treatment with the obligatory anaerobic pathogen Clostridioides difficile (C. difficile), however, resistance to the drug hampers its clinical success. The gold organometallic conjugate 2c was an efficient inhibitor of TrxR and it was inactive or showed only minor effects against eucaryotic cells and bacteria grown under aerobic conditions. In contrast, a strong antibacterial effect was observed against both metronidazole-sensitive and -resistant strains of C. difficile. This report presents a proof-of-concept that the design of metal-based hybrid antibiotics can be a viable approach to efficiently tackle AMR.Graphical abstractA metronidazole-gold hybrid metalloantibiotic with high efficacy against resistant C. difficile

Reversal of carbapenem resistance in Pseudomonas aeruginosa by camelid single domain antibody fragment (VHH) against the C4-dicarboxylate transporter.

Antimicrobial resistance is emerging as the new healthcare crisis necessitating the development of newer classes of drugs using non-traditional approaches. Pseudomonas aeruginosa, one of the most common pathogens involved in nosocomial infections, is extremely difficult to treat even with the last resort frontline drug, the carbapenems. As the pathogen has the ability to acquire resistance to new small-molecule antibiotics, being deployed, a novel biological approach has been tried using antibody fragments in combination with carbapenems and β-lactams as adjunct therapy for an enduring solution to the problem. In this study, we developed a camelid antibody fragment (VHH) library against P. aeruginosa and isolated a highly potent hit, PsC23. Mass spectrometry identified the target to be a component of the C4-dicarboxylate transporter that feeds metabolites to the glyoxylate shunt particularly under conditions of oxidative stress. PsC23 is bacteriostatic at a concentration of 1.66 µM (25 µg ml-1) and shows a synergistic effect with both the classes of drugs at an effective concentration of 100-200 nM (1.5-3.0 µg ml-1) when co administered with them. In combination with meropenem the VHH completely cleared the infection from a neutropenic mouse with a carbapenem-resistant P. aeruginosa systemic infection. Blocking the glyoxylate shunt by PsC23 resulted in disruption of energy transduction due to a respiratory shift to the oxygen-depleted TCA cycle causing inhibition of efflux and increased free radical generation from carbapenems and β-lactams exerting a strong bactericidal effect that reversed the resistance to multiple unrelated drugs.

Chitosan-derivative nanoparticles loaded with dihydromyricetin: Characterization, antibacterial and antioxidant activities

Bovine mastitis is a global problem and is mainly treated with antimicrobial agents that can significantly affect milk quality and threaten human health. The mammary gland can be damaged by the accumulation of reactive oxygen species (ROS), particularly during the perinatal period. Dihydromyricetin (DHM) has a wide range of pharmacological activities and is considered safe. However, its poor solubility, absorption, and bioavailability have limited its application. To address this issue, we designed and synthesized new chitosan-derivative nanoparticles (HACC-NPs) loaded with DHM, which have the potential to overcome its bioabsorption problems and enhance its antibacterial and antioxidant effects. We used the emulsification/crosslinking method to load DHM into chitosan-derivative nanoparticles (DHM/HACC-NPs); then, SEM, TEM and FTIR analyses were used to show a denser, more tightly packed matrix for the DHM/HACC-NPs, which were successfully prepared. The size (176.4 nm), polydispersity index (PDI, 0.21), and absolute value of the zeta potential (+26.3 mV) confirmed the stability of the DHM/HACC-NPs. More importantly, DHM/HACC-NPs had a stronger antibacterial effect on S. aureus (MIC = 0.52 mg/mL and MBC = 1.02 mg/mL) than on E. coli (MIC = 1.02 mg/mL and MBC = 2.05 mg/mL). Notably, DHM/HACC-NPs were concentration-dependent scavengers of DPPH and hydroxyl radicals. In summary, DHM/HACC-NPs exhibited superior biocompatibility and antimicrobial and antioxidant activities, offering new insights into the development of a robust, udder-stable drug platform as a promising strategy for treating dairy cow mastitis.

A biguanide chitosan-based hydrogel adhesive accelerates the healing of bacterial-infected wounds

The development of tissue adhesives with good biocompatibility and potent antimicrobial properties is crucial for addressing the high incidence of surgical site infections in emergency and clinical settings. Herein, an injectable hydrogel adhesive composed of chitosan biguanidine (CSG), oxidized dextran (ODex) and tannin (TA) was synthesized primarily through Schiff-base reactions, hydrogen bonding, and electrostatic interactions. TA was introduced into the CSG/ODex hydrogel to prepare a physicochemically double cross-linked hydrogel. The hydrogel formulation incorporating 2 wt% TA (CSG/ODex-TA2) exhibited rapid gelation, moderate mechanical properties, good tissue adhesion, and sustained release behavior of TA. Both in vitro and in vivo studies demonstrated that CSG/ODex-TA2 showed significantly enhanced adhesion and antibacterial effectiveness compared to the CSG/ODex hydrogel and commercial fibrin glue. Leveraging the positive charge of CSG, the CSG/ODex-TA2 hydrogel demonstrated a strong contact antibacterial effect, while the sustained release of TA provided diffusion antibacterial capabilities. By integrating contact and diffusion antibacterial mechanisms into the hydrogel, a promising approach was developed to boost antibacterial efficiency and accelerate the healing of wounds infected with methicillin-resistant Staphylococcus aureus (MRSA). The CSG/ODex-TA2 hydrogel has excellent biocompatibility, hemostatic properties, and antibacterial capabilities, making it a promising candidate for improving in vivo wound care and combating bacterial infections.

Targeted suppression of MEP pathway genes DXS, IspD and IspF to explore the mycobacterial metabolism and survival

Due to the uniqueness and essentiality of MEP pathway for the synthesis of crucial metabolites- isoprenoids, hopanoids, menaquinone etc. in mycobacterium, enzymes of this pathway are considered promising anti-tubercular drug targets. In the present study we seek to understand the consequences of downregulation of three of the essential genes- DXS, IspD, and IspF of MEP pathway using CRISPRi approach combined with transcriptomics in Mycobacterium smegmatis. Conditional knock down of either DXS or IspD or IspF gene showed strong bactericidal effect and a profound change in colony morphology. Impaired MEP pathway due to downregulation of these genes increased the susceptibility to frontline anti-tubercular drugs. Further, reduced EtBr accumulation in all the knock down strains in the presence and absence of efflux inhibitor indicated altered cell wall topology. Subsequently, transcriptional analysis validated by qRT-PCR of +154DXS, +128IspD, +104IspF strains showed that modifying the expression of these MEP pathway enzymes affects the regulation of mycobacterial core components. Among the DEGs, expression of small and large ribosomal binding proteins (rpsL, rpsJ, rplN, rplX, rplM, rplS, etc), essential protein translocases (secE, secY and infA, infC), transcriptional regulator (CarD and SigB) and metabolic enzymes (acpP, hydA, ald and fabD) were significantly depleted causing the bactericidal effect. However, mycobacteria survived under these damaging conditions by upregulating mostly the genes needed for the repair of DNA damage (DNA polymerase IV, dinB), synthesis of essential metabolites (serB, LeuA, atpD) and those strengthening the cell wall integrity (otsA, murA, D-alanyl-D-alanine dipeptidase etc.).

An on-demand antibacterial hydrogel for precise and rapid elimination of bacterial infection in a murine partial thickness scald burn wound

Burn wounds trigger prolonged inflammation, impair healing, and result in a high mortality rate. The effective management of burn patients requires a targeted approach to regulate the wound microenvironment, maintaining sterility while fostering conditions conducive to healing and functionality. Here, we developed a targeted antibacterial pH/temperature-responsive silver nanoparticle (AgNP) hydrogel triggering the release of silver ions based on changes in the burn wound microenvironment. The delivery system not only exerts a strong antibacterial effect owing to the localization and interfacial interaction of ultrasmall AgNPs against the bacterial surface and deeply embedded cells within the biofilm but also downregulates the bacterial pore-forming genes, thereby overwhelmingly deactivating bacterial responses through a multifaceted mechanism of action. We demonstrate that the application of AgNP hydrogel results in pH-dependent bacterial killing and elimination of over 95 % of pathogens while being non-toxic to mammalian cell viability and migration. Furthermore, the in vivo preclinical burn infection murine model demonstrates the eradication of S. aureus infection leading to a progressive burn repair supported by increased collagen deposition, anti-inflammatory properties, and increased burn angiogenesis. Overall, this strategy provides a targeted approach to addressing drug-resistant chronic burn infections, thereby contributing to improved management of burn injuries.

Biodegradable polyhydroxybutyrate microfiber membranes decorated with photoactive Ag‐TiO2 nanoparticles for enhanced antibacterial and anti‐biofouling activities

AbstractDeveloping advanced materials with antibacterial and antifouling activities offers an adequate protection solution against surface bacterial contamination—a common cause of infection threatening human health. The current work reports the preparation of polyhydroxybutyrate (PHB) microfiber membranes decorated with photoactive Ag‐TiO2 nanoparticles using electrospinning coupled with dip‐coating methods. The decoration of Ag‐TiO2 nanoparticles strongly enhances the antibacterial properties of prepared membranes, particularly under light illumination, thanks to their photocatalytic activity. The best‐performing sample exhibits potent antibacterial efficiency exceeding 99% against Escherichia coli and Staphylococcus epidermidis after 3 and 1 h of exposure to low‐power commercial LED light, respectively. The prepared samples also display excellent reusability with an insignificant antibacterial activity decrease after three cycles (<2% loss in antibacterial efficiency). Furthermore, these samples effectively prevent bacterial fouling due to their potent antibacterial properties. Notably, despite the strong antibacterial effect, decorated Ag‐TiO2 nanoparticles promote the adhesion of microorganisms, accelerating the biodegradation of PHB microfibers. As a result, the prepared microfiber membranes with nanoparticle decoration exhibit biodegradability comparable to the non‐decorated membrane, with the soil degradation rates reaching almost 99% after only 6 weeks.

Platelet-Rich Plasma/Chitosan/Chondroitin sulfate immunomodulatory hydrogel Co-Networks for diabetic wound Repair: Functions and molecular mechanisms

Diabetic wound healing encounters numerous challenges including bacterial infection, macrophage dysfunction, excessive inflammation, and oxidative stress, causing delays in the overlapping processes of inflammation, proliferation, and remodeling and thus imposing a high burden on patients. Platelet-rich plasma (PRP) has demonstrated significant potential for diabetic wound treatment by promoting granulation tissue formation, collagen deposition, re-epithelialization, and angiogenesis. However, the underlying molecular and cellular mechanisms remain unclear. Here, immunomodulatory hydrogel co-networks based on PRP, with strong hemostatic, antibacterial, and free radical scavenging effects, are developed for diabetic wound treatment. In vitro and in vivo, the hydrogels can reduce endothelial cell apoptosis and promote tube formation by regulating the oxidative stress microenvironment. For anti-inflammatory and tissue repair, the hydrogels can facilitate the M2 macrophage polarization by inhibiting phosphorylation of p-IκBα and p-P65 in the NF-κB signaling pathway. Through increasing the expression of key angiogenic factors (HIF-1α, VEGF, and FGF2), the hydrogels can significantly promote angiogenesis and the formation of endothelial cell tubular structures. These findings offer new insight into the synergistic regulatory contributions of the PRP-based therapy throughout multiple stages of healing, thereby establishing a biomolecular and cellular foundation for advanced diabetic wound management.

Phytic Acid-Promoted Deposition of Gold Nanoparticles with Grafted Cationic Polymer Brushes for the Construction of Synergistic Contact-Killing and Photothermal Bactericidal Coatings.

Medical implants are constantly facing the risk of bacterial infections, especially infections caused by multidrug resistant bacteria. To mitigate this problem, gold nanoparticles with alkyl bromide moieties (Au NPs-Br) on the surfaces were prepared. Xenon light irradiation triggered the plasmon effect of Au NPs-Br to induce free radical graft polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA), leading to the formation of poly(DMAEMA) brush-grafted Au NPs (Au NPs-g-PDM). The Au NPs-g-PDM nanocomposites were conjugated with phytic acid (PA) via electrostatic interaction and van der Waals interaction. The as-formed aggregates were deposited on the titanium (Ti) substrates to form the PA/Au NPs-g-PDM (PAP) hybrid coatings through surface adherence of PA and the gravitational effect. Synergistic bactericidal effects of contact-killing caused by the cationic PDM brushes, and local heating generated by the Au NPs under near-infrared irradiation, conferred strong antibacterial effects on the PAP-deposited Ti (Ti-PAP) substrates. The synergistic bactericidal effects reduced the threshold temperature required for the photothermal sterilization, which in turn minimized the secondary damage to the implant site. The Ti-PAP substrates exhibited 97.34% and 99.97% antibacterial and antiadhesive efficacy, respectively, against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), compared to the control under in vitro antimicrobial assays. Furthermore, the as-constructed Ti-PAP surface exhibited a 99.42% reduction in the inoculated S. aureus under in vivo assays. In addition, the PAP coatings exhibited good biocompatibility in the hemolysis and cytotoxicity assays as well as in the subcutaneous implantation of rats.

Transcriptome analysis reveals important regulatory factors for condensed tannins synthesis in acorn.

Condensed tannins are widely present in the fruits and seeds of plants and effectively prevent them from being eaten by animals before maturity due to their astringent taste. In addition, condensed tannins are a natural compound with strong antioxidant properties and significant antibacterial effects. Four samples of mature and near-mature Quercus fabri acorns, with the highest and lowest condensed tannin content, were used for genome-based transcriptome sequencing. The KEGG enrichment analysis revealed that the differentially expressed genes (DEGs) were highly enriched in phenylpropanoid biosynthesis and starch and sucrose metabolism. Given that the phenylpropanoid biosynthesis pathway is a crucial step in the synthesis of condensed tannins, we screened for significantly differentially expressed transcription factors and structural genes from the transcriptome data of this pathway and found that the expression levels of four MADS-box, PAL, and 4CL genes were significantly increased in acorns with high condensed tannin content. The quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) experiment further validated this result. In addition, yeast one-hybrid assay confirmed that three MADS-box transcription factors could bind the promoter of the 4CL gene, thereby regulating gene expression levels. This study utilized transcriptome sequencing to discover new important regulatory factors that can regulate the synthesis of acorn condensed tannins, providing new evidence for MADS-box transcription factors to regulate the synthesis of secondary metabolites in fruits.

Bioactive Lyocell Fibers with Inherent Antibacterial, Antiviral and Antifungal Properties.

Functional Lyocell fibers gain interest in garments and technical textiles, especially when equipped with inherently bioactive features. In this study, Lyocell fibers are modified with an ion exchange resin and subsequently loaded with copper (Cu) ions. The modified Lyocell process enables high amounts of the resin additive (>10%) through intensive dispersion and subsequently, high uptake of 2.7% Cu throughout the whole cross-section of the fiber. Fixation by Na2CO3 increases the washing and dyeing resistance considerably. Cu content after dyeing compared to the original fiber value amounts to approx. 65% for reactive, 75% for direct, and 77% for HT dyeing, respectively. Even after 50 household washes, a recovery of 43% for reactive, 47% for direct and 26% for HT dyeing is proved. XRD measurements reveal ionic bonding of Cu fixation inside the cellulose/ion exchange resin composite. A combination of the fixation process with a change in Cu valence state by glucose/NaOH leads to the formation of Cu2O crystallites, which is proved by XRD. Cu fiber shows a strong antibacterial effect against Staphylococcus aureus and Klebsiella pneumonia bacteria, even after 50 household washing cycles of both >5 log CFU. In nonwoven blends with a share of only 6% Cu fiber, a strong antimicrobial (CFU > log 5) and full antiviral effectiveness (>log 4) was received even after 50 washing cycles. Time-dependent measurements already show strong antiviral behavior after 30 s. Further, the fibers show an increased die off of the fungal isolate Candida auris with CFU log 4.4, and nonwovens made from 6% Cu fiber share a CFU log of 1.7. Findings of the study predestines the fiber for advanced textile processing and applications in areas with high germ loads.

Antibacterial and cytotoxicity activity of green synthesized silver nanoparticles using aqueous extract of naartjie (Citrus unshiu) fruit peels

The application of plant extracts in the green synthesis of silver nanoparticles (AgNPs) has attracted significant attention owing to their eco-friendliness and cost-effective features. However, nanoparticles synthesized from plant materials may also display unique physicochemical properties. This study described an improved synthesis process for silver nanoparticles (AgNPs) from the peel of the Citrus unshiu fruit, an agricultural waste product. In addition to evaluating the produced AgNPs' physico-chemical characteristics, the research also examines their antibacterial and cytotoxic/anticancer capabilities. The color change from yellow to dark brown was observed immediately when 20 ml of Citrus unshiu fruit peel extract was added to 0.5 g of silver nitrate. A surface plasmon resonance band at 424 nm revealed by ultra-violet spectroscopy was used as additional confirmation that AgNP had formed. The scanning electron microscope (SEM), and the transmission electron microscope (TEM), revealed spherical-shaped NPs with a mean size of 23 nm. Furthermore, X-ray diffraction (XRD) confirmed the high crystallinity of the obtained NPs while Fourier transform infrared spectroscopy (FTIR) confirmed the bioreducing capacity of the Citrus unshiu fruit peel extract. The minimum inhibitory concentration (MIC) (31.25 μg/mL) of AgNPs significantly revealed a strong dose-dependent antibacterial effect on Staphylococcus aureus and Bacillus cereus. In contrast, their impact on gram-negative bacteria, such as Escherichia coli and Salmonella typhimurium, displayed an MIC of 250 μg/mL. The assessment of cytotoxicity on human embryonic kidney cells (HEK293) and lung cancer cells (A549) through a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay revealed no detectable cytotoxic effects. The IC50 values were determined as 37.73 ± 0.34 μg/mL for HEK293 and 56.37 ± 0.73 μg/mL for A549, indicating the absence of significant adverse impacts on these cell lines. The anticancer drug doxorubicin was used as a reference standard, and had an IC50 value of 1.22 ± 0.09 and 0.76 ± 0.12 μg/mL against HEK293 and A549 cells, respectively. The results show that AgNPs synthesized from Citrus unshiu fruit peel could serve as antibacterial agents that may in the future be optimized for us in for example nanofiltration systems.

Nanoparticles on pathogenic strains of Staphylococcus aureus and Escherichia coli

Background: Nanoparticles are increasingly being used as an alternative antibiotic to target microorganisms, particularly for treating bacterial infections. In current study it was recognized processes such as metal ion release, induction of oxidative stress, and non-oxidative mechanisms. Developing resistance to nanoparticles is challenging for bacterial cells due to the multiple simultaneous actions against microorganisms, and require several simultaneous gene alterations within the same bacterial cell. Objective: To determine the effect of the titanium dioxide nanoparticles (TiO2NPs) on the activity of the same bacteria that participate in dental caries (Staphylococcus aureus and Escherichia coli). Patients and Methods: The study included 50 patients who attended the dental clinic and took the samples by the wooden swap from the molar area (cervical area of inflamed gingiva and same samples taken from occlusal surface of molar). The collected samples were cultured on “Mannitol salt agar, Blood agar, and MacConkey's agar plates” for separation of the needed bacteria (Staphylococcus aureus and Escherichia coli) that showed wide spreading in the oral cavities and dental carries. TiO2NPs are then created using pulse laser ablation, followed by coating preparation the nanoparticles materials (using a hybrid sol-gel and organ silicate nanoparticles), and finally the prepared nanoparticles to the coating solution and local paint were used for antimicrobial activity of the separated bacteria using different concentrations of TiO2 in the cultures. Results: Characterization showed the phase of the TiO2NPs was spherical, with very few irregularly shaped particles, and had an average small size in millimeters. Antimicrobial activity results showed a strong bactericidal effect against Gram-positive bacteria and demonstrated greater sensitivity to TiO2 nanoparticles at lower concentrations when compared to Gram-negative bacteria. Conclusion: It was shown that nanotechnology promise in treating various infections caused by bacteria, including dental caries. Notably, nanoparticles have demonstrated broad-spectrum antibacterial effects against Gram-positive bacteria. Keywords: TiO2, nanoparticles, Staphylococcus aureus, and E. coli

Electron Microscope Scanning, and Antibacterial Activity of Tio2 Nanoparticles on pathogenic strains of Staphylococcus aureus and Escherichia coli

Background: Nanoparticles are increasingly being used as an alternative antibiotic to target microorganisms, particularly for treating bacterial infections. In current study it was recognized processes such as metal ion release, induction of oxidative stress, and non-oxidative mechanisms. Developing resistance to nanoparticles is challenging for bacterial cells due to the multiple simultaneous actions against microorganisms, and require several simultaneous gene alterations within the same bacterial cell. Objective: To determine the effect of the titanium dioxide nanoparticles (TiO2NPs) on the activity of the same bacteria that participate in dental caries (Staphylococcus aureus and Escherichia coli). Patients and Methods: The study included 50 patients who attended the dental clinic and took the samples by the wooden swap from the molar area (cervical area of inflamed gingiva and same samples taken from occlusal surface of molar). The collected samples were cultured on “Mannitol salt agar, Blood agar, and MacConkey's agar plates” for separation of the needed bacteria (Staphylococcus aureus and Escherichia coli) that showed wide spreading in the oral cavities and dental carries. TiO2NPs are then created using pulse laser ablation, followed by coating preparation the nanoparticles materials (using a hybrid sol-gel and organ silicate nanoparticles), and finally the prepared nanoparticles to the coating solution and local paint was used for antimicrobial activity of the separated bacteria using different concentrations of TiO2 in the cultures. Results: Characterization showed the phase of the TiO2NPs was spherical, with very few irregularly shaped particles, and had an average small size in millimeters. Antimicrobial activity results showed a strong bactericidal effect against Gram-positive bacteria and demonstrated greater sensitivity to TiO2 nanoparticles at lower concentrations when compared to Gram-negative bacteria. Conclusion: It was shown that nanotechnology promise in treating various infections caused by bacteria, including dental caries. Notably, nanoparticles have demonstrated broad-spectrum antibacterial effects against Gram-positive bacteria.

Efficient chlorine evolution of CuO modified RuO2 electrode and its application in preparation of electrochemical disinfectant

Electrochemical chlorine evolution reaction (CER) is one of the most important practical applications of electrochemical reaction, which can be used for electrochemical disinfection. The electrochemical disinfectant of acidic electrolyzed water (AEW) is obtained by electrolyzing extremely dilute chlorine-containing solution in ion-exchange membrane electrolyzer. In the anode area, HClO is produced by CER, which has a strong bactericidal effect. Due to the low concentration of chloride ion, it is necessary to improve the CER selectivity of the electrode in order to improve the efficiency of chlorine electrolysis. In this paper, CuO/RuO2 electrode was prepared by the two-step thermal decomposition method, and the surface morphology and electronic structure of RuO2 electrode were modified. Compared with the ordinary RuO2 electrode, the CER activity of CuO/RuO2 electrode is improved. For the oxygen evolution reaction (OER), the activity of CuO/RuO2 electrode is significantly lower than that of RuO2 electrode. The CER mechanism of CuO/RuO2 electrode is the second electron transfer, and the OER mechanism is the formation and transformation of OHads. The potential difference between CER and OER of CuO/RuO2-3 electrode is 105 mV, which is 52 mV higher than that of RuO2 electrode, so the selectivity of CER of CuO/RuO2 electrode is remarkably improved. During the preparation of AEW, the HClO of AEW2 (prepared by CuO/RuO2-3 electrode) is 0.72 mmol/L, which is 2.5 times that of AEW1 (prepared by RuO2 electrode). In the sterilization experiments on E. coli and B. subtilis, the germicidal efficacy of AEW2 (3.71 and 2.99 log10 CFU/mL) is obviously superior to that of AEW1 (0.76 and 0.61 log10 CFU/mL).

Silver Organometallics that are Highly Potent Thioredoxin and Glutathione Reductase Inhibitors: Exploring the Correlations of Solution Chemistry with the Strong Antibacterial Effects.

The antibacterial activity of silver species is well-established; however, their mechanism of action has not been adequately explored. Furthermore, issues of low-molecular silver compounds with cytotoxicity, stability, and solubility hamper their progress to drug leads. We have investigated silver N-heterocyclic carbene (NHC) halido complexes [(NHC)AgX, X = Cl, Br, and I] as a promising new type of antibacterial silver organometallics. Spectroscopic studies and conductometry established a higher stability for the complexes with iodide ligands, and nephelometry indicated that the complexes could be administered in solutions with physiological chloride levels. The complexes showed a broad spectrum of strong activity against pathogenic Gram-negative bacteria. However, there was no significant activity against Gram-positive strains. Further studies clarified that tryptone and yeast extract, as components of the culture media, were responsible for this lack of activity. The reduction of biofilm formation and a strong inhibition of both glutathione and thioredoxin reductases with IC50 values in the nanomolar range were confirmed for selected compounds. In addition to their improved physicochemical properties, the compounds with iodide ligands did not display cytotoxic effects, unlike the other silver complexes. In summary, silver NHC complexes with iodide secondary ligands represent a useful scaffold for nontoxic silver organometallics with improved physicochemical properties and a distinct mechanism of action that is based on inhibition of thioredoxin and glutathione reductases.