Antibacterial action and target mechanisms of zinc oxide nanoparticles against bacterial pathogens

ZnO nanoparticles enhance the efficiency of sodium hypochlorite disinfectant in reducing the adhesion of pathogenic bacteria to stainless steel surfaces

The use of commercial disinfectant in combination with other antimicrobial agent such as ZnO nanoparticles to improve disinfection efficacy could be a promising strategy in the control of pathogenic bacteria. In this context, the aim of study was to determine the minimum inhibitory concentration (MIC) of sodium hypochlorite disinfectant, ZnO nanoparticles as well as Mn-, Ce-, and Co-doped ZnO nanoparticles (doping concentrations 10%, 20%, 30%) against gram-negative bacteria Escherichia coli and Salmonella Typhimurium, and gram-positive bacteria Staphylococcus aureus and Listeria monocytogenes using the broth microdilution method CLSI M07-A10, while the checkerboard microdilution method was carried out to assess the type interaction of sodium hypochlorite in combination with pure ZnO nanoparticles. The results specified that ZnO nanoparticles were agents that required higher concentrations to inhibit bacterial growth than sodium hypochlorite, whereby a synergistic effect was achieved in their combination. It was also revealed that doping of Mn and Co in ZnO nanoparticles improved antibacterial activity against gram-positive bacteria. Generally, this study aimed to evaluate the effectiveness of individual treatments (sodium hypochlorite and ZnO nanoparticles) and their combination on initial bacterial adhesion to stainless steel surfaces (AISI 304) exposed to different temperatures (7 °C, 25 °C, 37 °C) and pH (4.5, 7.0, 8.5) using colony-forming units count method. It was evident that ZnO nanoparticles were more effective than sodium hypochlorite in reducing bacterial adherence, while the combined tretmant showed a better effect than any individual treatment alone, highlighting its advantages as a novel disinfectant to prevent bacterial biofilms. Furthermore, data that temperature and pH affected bacterial adhesion provide comprehensive insight how bacteria survive in the food processing environments, which could assist in assessment the risk of contamination.

Cardamom essential oil-loaded zinc oxide nanoparticles: A sustainable antimicrobial strategy against multidrug-resistant foodborne pathogens

The globalization of the food trade has escalated challenges in ensuring food safety due to foodborne pathogens, including multidrug-resistant (MDR) strains, which pose significant public health risks and economic burdens. Innovative antimicrobial strategies are urgently required. In this study, cardamom essential oil-loaded zinc oxide nanoparticles (CEO-ZnO-NPs) were synthesized and evaluated for their antimicrobial potential and mechanisms of action against MDR Escherichia coli and Staphylococcus aureus. Dynamic light scattering and the transmission electron microscopy (TEM) micrograph confirmed a spherical nanocomposite with an average size of 141.4 nm with good dispersion and stability over 180 days. Antimicrobial activity assessed via the agar well diffusion method showed dose-dependent inhibition, with zones of 25.75 ± 0.90 mm for E. coli and 31.05 ± 0.46 mm for S. aureus at 400 μg/mL. Minimum inhibitory concentrations (MIC) were 25 μg/mL (E. coli) and 12.5 μg/mL (S. aureus), while minimum bactericidal concentrations (MBC) were 50 μg/mL and 25 μg/mL, respectively. Kill-time analysis revealed a marked reduction in bacterial viability after 120 min of exposure. Mechanistic studies using scanning electron microscopy showed structural damage, including disrupted membranes and cell shrinkage. Also, protein levels significantly decreased, with DNA and ATP levels reduced by 74.51 % and 91.15 % in E. coli and 79.40 % and 90.81 % in S. aureus. Enzymatic activities, including ATPase and alkaline phosphatase, were inhibited by up to 84.63 %. In addition, the low cytotoxicity of CEO-ZnO-NPs against Vero cells supporting their potential biosafety for food safety applications. These findings demonstrate that CEO-ZnO-NPs disrupt bacterial processes such as protein synthesis, membrane integrity, and enzymatic activity, offering a promising approach that aligns with the United Nations Sustainable Development Goals (SDGs), particularly SDGs 2, 3, and 12, while promoting circular economy principles by reducing reliance on synthetic preservatives to address antimicrobial resistance in foodborne pathogens.

Enhanced photocatalytic degradation of norfloxacin and amido black 10B using bael gum-infused ZnO/Ag₂CO₃ nanocomposites for sustainable approach to environmental remediation and antimicrobial activity

The presence of antibiotics and dyes as organic contaminants has caused severe wastewater pollution, posing a significant environmental concern globally. To address this issue, this study highlights the green synthesis of ZnO/Ag₂CO₃ nanocomposites using bael gum (BG) for the photocatalytic degradation of norfloxacin (NOF) and Amido Black 10B (AB 10B), along with their antimicrobial activity. The synthesized BG-ZnO/Ag₂CO₃ nanocomposites were extensively characterized for their optical, structural, morphological, chemical purity, crystal structure, and surface area properties using XPS, XRD, FT-IR, FESEM, EDS, photoluminescence (PL) spectra, Raman analysis, HR-TEM, BET, and LC-MS. The nanocomposites materials exhibited excellent photocatalytic performance under visible light irradiation, achieving the degradation efficiencies of 91.03 % for AB 10B and 81.5 % for NOF,with corresponding rate constants of 0.017 min-1 and 0.0028 min-1. The study further evaluated the influence of catalyst dosage, effect of pH, radical scavengers, reusability, and the stability. Kinetic analysis revealed that the bio-nanocomposite follows first-order kinetics for both pollutants. Scavenger studies identified hydroxyl radicals (•OH) as the primary active species in the degradation process. LC-MS analysis confirmed the formation of degradation intermediates for NOF and AB 10B. Additionally, the bio-nanocomposite demonstrated significant antibacterial activity against various bacterial strains using the agar well diffusion method, exhibiting strong bactericidal effects against pathogenic bacteria. This study emphasizes the potential of bael gum-based bio-nanocomposites for improved photocatalytic degradation and antibacterial activity in wastewater treatment across various industries.

Functionalization of cotton fabric using the biogenic synthesized silver nanoparticles for enhanced dye reduction and antimicrobial efficiency: Response surface methodology

This study explores the eco-friendly synthesis of silver nanoparticles (AgNPs) using Spirulina extract and their application for cotton fabrics functionalization in order to enhance the photocatalytic and antimicrobial properties. The small size of the synthesized AgNPs was confirmed using Transmission Electron Microscopy (TEM) and dynamic light scattering (DLS), revealing a spherical morphology with an average size of 8.6 nm. The functionalized cotton fabric exhibited excellent catalytic activity, achieving 100 % Congo red (CR) dye reduction at pH 9, and 45 °C for 120 min. Response surface methodology (RSM) optimization using the Box-Behnken Design (BBD) demonstrated a high correlation (R2 = 0.987) between process variables and catalytic performance. The recyclability of the AgNPs-coated cotton fabric was evaluated over 5 cycles, showing a slight decrease in efficiency to 81.6 % in the 5th cycle, indicating its durability and potential for repeated use. In antimicrobial evaluations, the AgNPs-coated fabric exhibited superior inhibition against multiple pathogenic microorganisms, including Acinetobacter baumannii (42 mm inhibition zone), Klebsiella pneumoniae (39 mm), Pseudomonas aeruginosa (41 mm), Staphylococcus aureus (37 mm), Enterococcus faecalis (35 mm), and Candida albicans (34 mm). The antibacterial efficiency exceeded that of standard ciprofloxacin, highlighting the significant potential of AgNPs-coated cotton fabric in biomedical and industrial applications. These results establish AgNPs-coated cotton fabric as a promising material for wastewater treatment and antimicrobial applications, supporting sustainable advancements in nanotechnology and textile engineering.

Developing sustainable approach for controlling foodborne pathogens, based on chlorella vulgaris extract/alginate nanoemulsion, and enhanced via the dispersed zinc oxide nanoparticles

A promising antibacterial strategy was developed in this study to effectively eradicate foodborne pathogens via the synergism of Chlorella vulgaris extract (CVE) with zinc oxide nanoparticles (ZNPs) combined into a single nanoform. CVE-alginate nanoemulsion with enhanced antimicrobial and antioxidant properties via the dispersed ZNPs, were prepared and characterized using UV-Vis spectra, FE-SEM-EDX, TEM, DLS, FTIR. The CVE methanol extract was analyzed to record total phenolic and total flavonoid contents. Drug release pattern, encapsulation efficiency, antioxidant, antimicrobial, hemolysis and cytotoxicity were demonstrated. According to TEM and SEM imaging, produced NEs appeared spherical in nanoscale with the range of 17-23.6 nm. The results showed that when the active CVE-NE I dispersed with 1 % or 2 % ZNPs, was applied, exhibited more potent antibacterial properties against the tested foodborne pathogens, including S. aureus, E. coli, S. typhimurium, and B. subtilis, compared to CVE-NE I. CVE was released in slow and sustained manner by addition of ZNPs. All NE samples showed no obvious hemolysis or cytotoxicity when applied on fibroblast cells. These encouraging results offer a fresh approach to the efficient removal of foodborne pathogens, which may be used in food industry.

Antimicrobial and antibiofilm activity of prepared thymol@UIO-66 and thymol/ZnONPs@UIO-66 nanoparticles against Methicillin-resistant Staphylococcus aureus: A synergistic approach

This study introduces a novel approach to enhance the antibacterial properties of UIO-66 by incorporating both Thymol and ZnO nanoparticles within its framework which represents a significant advancement like exhibiting a synergistic antibacterial effect, providing a prolonged and controlled release, and mitigating cytotoxicity associated with the release of free ZnO nanoparticles by combining these two antimicrobial agents within a single, well-defined metal-organic framework. UIO-66 frameworks are investigated as carriers for the natural antimicrobial agent, Thymol, and ZnONPs offering a novel drug delivery system for antibacterial applications. Results demonstrated 132, 90, 184, and 223 nm sizes for UIO-66, ZnONPs, UIO-66 encapsulated Thymol, and UIO-66 encapsulated both Thymol and ZnONPs, respectively. Successful encapsulation of the antibacterial drug with a high entrapment efficiency of 64 % for Thymol was approved, and 49 % in-vitro release of Thymol was achieved for 72 hours. In-vitro antibacterial assays revealed promising results, with the drug-loaded nanoparticles exhibiting significantly lower MIC values and enhanced bactericidal activity against S. Aureus bacterial strains compared to the free drug, as demonstrated by agar disk diffusion and time-kill assays. MIC values reduced from a range of 31.25-250 µg/ml for free Thymol and 12.5-100 µg/ml for free ZnONPs to 3.9-62.5 µg/ml for Thymol@UIO-66 and 1.95-15.63 µg/ml for Thymol/ZnONPs@UIO-66. According to the results, the mixture of both Thymol and ZnONPs had 41 % and 16 % more antibiofilm activities in comparison with free Thymol and free ZnONPs, respectively. Furthermore, Thymol@UIO-66 had 25 % higher antibiofilm activities relative to not-encapsulated Thymol and ZnONPs, and this improvement was even 46 % more in Thymol/ZnONPs@UIO-66 in comparison with Thymol@UIO-66. Overall, this study demonstrates the potential of Thymol/ZnONPs@UIO-66 frameworks as a promising drug delivery platform for effective antibacterial therapy. This approach to overcome antibiotic resistance and improve treatment efficacy potentially.

Exploring the antivirulence mechanisms of ZnO-PEG-quercetin nanoparticles: Biofilm disruption, attenuation of virulent factors, and cell invasion suppression against pathogenic Pseudomonas aeruginosa

The dense biofilm architecture and efflux pump activity play critical roles in Pseudomonas aeruginosa infections by hindering the accumulation and long-term efficacy of antibacterial agents within bacterial cells. The development of engineered nanoparticles capable of penetrating the polysaccharide matrix of biofilms represents a promising strategy for addressing bacterial infections. This is the first report on the synthesis of quercetin-functionalized PEGylated ZnO nanoparticles (ZnO-PEG-QUE NPs) and the evaluation of their anti-biofilm activity against pathogenic strains of P. aeruginosa. The synthesized NPs exhibited spherical shapes with an average size of 59.52 nm. ZnO-PEG-QUE NPs demonstrated biofilm inhibitory levels between 49 % and 67 %, and significantly reduced the production of total exopolysaccharides, alginate, and pellicle by 64.61 %-71.69 %, 30.47 %-45.36 %, and 24.22 %-85.97 %, respectively. ZnO-PEG-QUE NPs not only inhibited early-stage biofilm formation but also disrupted mature biofilms, indicating a dual mode of action against both biofilm development and persistence. Based on our findings, ZnO-PEG-QUE NPs effectively eradicated mature biofilms by 67.2 %-72 % and significantly reduced the metabolic activity and viable cells of preformed biofilms to 34.12 %-55.57 % and 6.25-8.15 log CFU, respectively. Electron and fluorescence microscopy analyses also confirmed the antibiofilm potential of ZnO-PEG-QUE NPs. Furthermore, bacterial adhesion and invasion to HDF cells were significantly diminished in the NP-treated groups. The attenuation of efflux pump activity in the NP-treated strains was confirmed using the EtBr-agar cartwheel assay. Taken together, these findings highlight the therapeutic potential of ZnO-PEG-QUE NPs as a novel and effective strategy to combat biofilm-associated infections, warranting further investigation in preclinical models.

Carboxymethyl bacterial cellulose electrospun nanofibers loaded with zinc oxide nanoparticles and polyhexamethylene biguanide for wound healing promotion

This study explores the development of a novel wound dressing incorporating bacterial cellulose (BC) produced by Acetobacter xylinum, which was carboxymethylated to enhance its biomedical applicability. Zinc oxide nanoparticles (ZnONPs) were biosynthesized using a green method with Quercus infectoria gall extracts (QIG). The composite dressing, composed of BC and polyurethane (PU) nanofibers, was further functionalized with ZnONPs and polyhexamethylene biguanide (PHMB) to provide enhanced antibacterial and wound healing properties. The PU/BC/ZnONPs/PHMB nanofiber mat exhibited strong antibacterial activity against Methicillin-resistant Staphylococcus aureus (MRSA), with inhibition zones of 28 and 29 mm for PU/BC/ZnONPs and PU/BC/ZnONPs/PHMB, respectively, surpassing the 12 mm inhibition zone of the Cefoxitin control. The nanofibers had an optimal mean diameter of 71.12 nm, ensuring a high surface area for cell attachment. Mechanical tests confirmed excellent tensile strength and flexibility, while an optimized water vapor transmission rate (∼2000-3000 g/m2/day) facilitated a moist wound environment for enhanced healing. L929 fibroblast studies demonstrated high cell viability (∼95-98%) and enhanced migration, confirming the nanofiber mat's biocompatibility. In vivo wound healing tests showed that PU/BC/ZnONPs/PHMB significantly accelerated wound closure, achieving 90-100% healing by day 10, outperforming PU and PU/BC groups. Bacterial counts were significantly reduced, with complete bacterial inhibition observed by day 5. In conclusion, the PU/BC/ZnONPs/PHMB nanofiber dressing demonstrated superior antibacterial activity, mechanical strength, moisture regulation, and wound healing potential, making it a promising candidate for advanced clinical wound management.

Novel ZnO/polyacrylate composites with antibacterial activity against C. ammoniagenes to prevent skin infections

Much of the older population experiences urinary incontinence disorders and often relies on medical supplies such as diapers or pads. However, frequent use of these supplies can lead to unpleasant odors, skin irritations, and infections caused by a bacterium found in human urine called Corynebacterium ammoniagenes. To address the hygiene and health concerns associated with these supplies, novel composite materials consisting of zinc oxide impregnated on sodium polyacrylate were synthesized through diverse methods. These composites were then tested against the C. ammoniagenes bacterium to assess their viability as components of urinary incontinence supplies. Overall, the synthesized composites exhibited considerable efficacy against the targeted bacterium. Moreover, the sample synthesized with more water used in sodium polyacrylate dispersion demonstrated the highest level of inhibition. Complete bacterial inhibition was achieved within 24 h of contact, with a minimum inhibitory concentration of 1.66 mg/mL. The results indicate that the synthesized composites hold significant potential for addressing the hygiene and health concerns associated with urinary incontinence supplies, presenting a promising avenue for improving the quality of life of individuals affected by this condition.

Potential Therapeutic Effect of ZnO/CuO Nanocomposite as an Acaricidal, Immunostimulant, and Antioxidant in Rabbits

The present study aimed to identify a safe and novel approach using zinc oxide/copper oxide nanocomposites (AZ) to enhance growth parameters, immunity, and fight Sarcoptic mange in vitro and in vivo in rabbits. In vitro: the acaricidal activity of AZ was assessed at concentrations of AZ-25: 2.5% w/w AZ/molasses, AZ-125: 12.5% w/w AZ/molasses, and controls (normal saline, molasses, and Ivermectin) every hour for seven hours under a stereoscopic microscope. In vivo: involved 40 rabbits (10 replicates/group). G1 served as the control negative group (normal un-infected rabbits), G2 served as the control negative group (infected rabbits), the animals in the G3 group were given a combination of AZ (40 mg/kg body weight (BW)) and molasses (5 mg/mL), and G4 served as the control to the vehicle; receiving molasses 8 mL/kg BW twice weekly for 6 weeks. Blood, serum, and tissue samples were collected at the middle and the end of the trial. AZ was made using the sonication sol-gel method. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were performed to confirm the crystal structure, purity, particle size, and oxidation states. AZ showed immunostimulant, acaricidal, and antioxidant effects with normal tissue histological structure and low tissue residual levels. Additionally, there were improvements in blood interferon-gamma, immunoglobulin (Ig) M, IgG, phagocytic activity, phagocytic index, globulin, and total protein in the AZ group. The XRD patterns of AZ were coordinated by XRD reference codes Crystallography Open Database (COD): 9016326 for Tenorite (CuO) and by XRD reference COD: 9004179 for Zincite (ZnO). The CuO and ZnO crystal sizes were 21.87 Å and 24.89 Å, respectively. The XPS spectra indicated the presence of Cu as Cu (II) and Zn as ZnO.OH and ZnO. In conclusion, AZ exhibited antioxidant, acaricidal, and immunostimulant effects, with mild residues in the brain, liver, and kidney tissues, while maintaining a normal histological structure of tissues.

Synthesis, characterization, anticancer, antibacterial and antifungal activities of nanocomposite based on tertiary metal oxide Fe2O3@CuO@ZnONPs, starch, ethylcellulose and collagen

This study aimed to synthesize a nanocomposite based on tertiary metal oxide Fe2O3@CuO@ZnONPs, starch, ethylcellulose, and collagen, as well as evaluate its biological activities. The prepared nanocomposites were characterized using physicochemical analysis, which included FTIR, XRD, and DLS. Additionally, topographical analysis using FI-SEM, EDX, mapping, HR-TEM, and SAED affirmed the molecular structure and nanosized of formulated nanocomposites. Moreover, DLS performed a size of free nanocomposite (Bnanocomp) and trimetallic loaded nanocomposite (Lnanocomp) as 158 and 105 nm, respectively. The synthesized loaded nanocomposite with metal oxides (Lnanocomp) was assessed for cytotoxicity on normal and cancerous cell lines. Results revealed that the IC50 of Lnanocomp toward Wi-38 normal cell line was 196.4 μg/mL; this confirms that Lnanocomp is non-toxic and safe in use. Moreover, Lnanocomp displayed anticancer activity against Hep-G2 with IC50 53.7 μg/mL. Furthermore, Lnanocomp displayed potential antibacterial activity toward E. coli, P. aeruginosa, S. typhimurium, S. aureus, and B. subtilis with MICs 50, 50, 12.5, 50, and 25 μg/mL, respectively. Also, Lnanocomp exhibited antifungal activity where MIC was 200, 50, and 100 μg/mL toward C. albicans, A. fumigatus, and A. brasilienisis respectively. In conclusion, the prepared Fe2O3@CuO@ZnONPs-based nanocomposite shows promising synergetic antibacterial, antifungal, and anticancer activities with state biocompatibility.

Evaluation of the interface of metallic-coated biodegradable polymeric stents with prokaryotic and eukaryotic cells

Polymeric coronary stents, like the ABSORB™, are commonly used to treat atherosclerosis due to their bioresorbable and cell-compatible polymer structure. However, they face challenges such as high strut thickness, high elastic recoil, and lack of radiopacity. This study aims to address these limitations by modifying degradable stents produced by additive manufacturing with poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) with degradable metallic coatings, specifically zinc (Zn) and magnesium (Mg), deposited via radiofrequency (rf) magnetron sputtering. The characterisation included the evaluation of the degradation of the coatings, antibacterial, anti-thrombogenicity, radiopacity, and mechanical properties. The results showed that the metallic coatings inhibited bacterial growth, though Mg exhibited a high degradation rate. Thrombogenicity studies showed that Zn-coated stents had anticoagulant properties, while Mg-coated and controls were thrombogenic. Zn coatings significantly improved radiopacity, enhancing contrast by 43 %. Mechanical testing revealed that metallic coatings reduced yield strength and, thus, diminished elastic recoil after stent expansion. Zn-coated stents improved cyclic compression resistance by 270 % for PCL stents, with PLA-based stents showing smaller improvements. The coatings also enhanced crush resistance, particularly for Zn-coated PCL stents. Overall, Zn-coated polymers have emerged as the premier prototype due to their superior biological and mechanical performance, appropriate degradation during the stent life, and ability to provide the appropriate radiopacity to medical devices.

Single-atom Zr doped heterojunction enhanced piezocatalysis for implant infection therapy through synergistic metal immunotherapy with sonodynamic and physical puncture

Recent common clinical treatments for implant bacterial infections involve replacing inert implants and using antibiotics. However, these methods remain limited in their effectiveness for pathogen clearance, immune regulation, and osteogenesis. In this study, we developed a Zr-doped heterointerface of SrTiO3 and Hap (SrTiZrO3/Hap) heterojunction coating with single-atom Zr doping and heterogeneous interfaces designed for ultrasound-responsive antimicrobial activity and bone formation. Under ultrasound, the mechanical force exerted by SrTiZrO3/Hap enhances its physical puncture and sonodynamic activity, synergizing with the metalloimmunotherapy effect of Zr4+ for efficient antimicrobial activity. The primary mechanism enhancing sonodynamic activity involves local interfacial polarization from single-atom Zr doping, achieving piezoelectric catalysis in conjunction with electronic polarization from the built-in electric field. SrTiZrO3/Hap achieved a 99.3% antibacterial rate against S. aureus and 99.7% against E. coli under ultrasound. Additionally, SrTiZrO3/Hap promoted osteogenic differentiation after ultrasound irradiation by activating the PI3K/Akt pathway via its piezoelectric, needle-like topological surface and the release of functional ions, thus accelerating bone repair.

Anticancer, antioxidant and antibacterial potential of L-Glutaminase (Streptomyces roseolus strain ZKB1) capped silver and zinc oxide nanoparticles and its molecular characterization

The current investigation reports anti-cancer, antioxidant and antibacterial potential of L-Glutaminase (Streptomyces roseolus strain ZKB1) and L-Glutaminase capped nanoparticles. The highest L-Glutaminase production of 9.57 U/mL was achieved on the 4th day of fermentation when L-Glutamine was used as the sole carbon and nitrogen source. Enhanced recycling stability was observed after 6 cycles using L-Glutaminase immobilized in 3% agar and agarose matrices. Free and immobilized L- Glutaminase showed Km of 13.89 ± 0.8 and 7.13 ± 0.3 mM and Vmax of 18.40 ± 1.5 and 24.21 ± 1.7 U/mg respectively. L- Glutaminase capped silver (AgNP) and zinc oxide (ZnONP) nanoparticles were synthesized and structurally characterized using UV visible spectroscopy, FTIR, SEM-EDS, XRD and AFM. L- Glutaminase capped AgNP and ZnONP exhibited good thermal stability with five and three stages weight loss pattern respectively based on TGA. L-Glutaminase capped AgNP exhibited highest inhibitory activity against B. subtilis (45 ± 0.5 mm) and E. coli (33 ± 0.8 mm) whereas, L-Glutaminase capped ZnONP demonstrated highest inhibition against E. coli (30 ± 0.3 mm) and B. cereus (25 ± 0.5 mm). Increased nanoparticles concentration exhibited increased inhibitory potential as compared to wild L-Glutaminase and lowest MIC of 0.09 µg/mL was exhibited against B. cereus. L-Glutaminase capped nanoparticles demonstrated significant antioxidant properties through in-vitro ABTS and DPPH radical scavenging assays in a dosage-dependent manner. L-Glutaminase and capped AgNP and ZnONP, demonstrated pronounced cell cytotoxicity against MCF-7 cancerous cell line with 57.17 µg/mL, 8.13 µg/mL and 28.31 µg/mL IC50 values respectively, suggesting promising properties as anticancer agents in enzyme-based therapy. The results reveal promising biological activities with potential applications in healthcare sector.

ZnO-Cu/Mn nanozyme for rescuing the intestinal homeostasis in Salmonella-induced colitis

Salmonella is one of the most common foodborne pathogens, which can cause severe enteritis and intestinal microbiota imbalance. However, there are limited strategies currently available for preventing or treating Salmonella-induced colitis. Herein, we developed the Cu/Mn-co-doped ZnO tandem nanozyme (ZnO-CM) with pH-responsive multienzyme-mimicking activities via doping engineering for the treatment of Salmonella-induced colitis. Benefiting from the co-doping of Cu and Mn, ZnO-CM nanospheres exhibit remarkable peroxidase-like activity in acidic condition and superoxide dismutase- and catalase-like activities in neutral environment. Animal experiments show that ZnO-CM can efficiently inhibit bacterial growth, alleviate inflammation, and restore the intestinal barrier, resulting in good antibacterial and anti-inflammatory effects on Salmonella-induced colitis. Mechanistically, ZnO-CM functions through inhibiting the continuous accumulation of ROS, increasing the levels of tight junction proteins occludin and claudin-1, and decreasing the expression of pro-inflammatory cytokines IL-1β and IL-6 in intestine. This work not only presents an effective paradigm for Salmonella-induced colitis therapy, but also provides new sights into the prevention and treatment of other bacterial enteritis.

Dual-responsive polydopamine-embellished Zn-MOFs enabling synergistic photothermal and antibacterial metal ion therapy for oral biofilm eradication

Oral biofilms are associated with various oral diseases causing pain and discomfort, and pose a severe threat to general health. Conventional surgical debridement and antibacterial therapy often yield unsatisfactory outcomes because they either fail to fully and painlessly eliminate biofilms or increase the risk of bacterial resistance. In this study, we synthesized polydopamine-embellished Zn-MOFs (ZIF-8@PDA NPs), which can degrade under mildly acidic conditions to release Zn2+. These nanoparticles also convert near-infrared light energy into heat, thereby enabling synergistic photothermal and antibacterial metal ion therapy for oral biofilm eradication. Our findings reveal that therapy with ZIF-8@PDA NPs, when exposed to near-infrared radiation, demonstrates exceptional antibacterial efficacy and is highly effective in eradicating oral biofilms both in vitro and ex vivo. Furthermore, we used an in vivo rodent tooth biofilm model to demonstrate the suppression of dental caries. This work presents a promising solution for preventing and suppressing dental caries as well as other treating diseases linked to oral biofilm infections.

Harnessing Stevia rebaudiana for Zinc Oxide Nanoparticle Green Synthesis: A Sustainable Solution to Combat Multidrug-Resistant Bacterial Pathogens

The rise of multidrug-resistant (MDR) bacteria in food products poses a significant threat to public health, necessitating innovative and sustainable antimicrobial solutions. This study investigates the green synthesis of zinc oxide nanoparticles (ZnO-NPs) using Stevia rebaudiana extracts to evaluate their antibacterial and antibiofilm activities against MDR Staphylococcus aureus strains isolated from sold fish samples. The obtained results show that the contamination with S. aureus reached 54.2% in the tested fish samples (n = 120), underscoring the urgent need for effective interventions. ZnO-NPs were successfully synthesized and characterized using UV-visible spectroscopy, FT-IR, XRD, and TEM, confirming their formation with an average size of 15.7 nm and reflecting their suitability for antimicrobial and biological applications. ZnO-NPs exhibited potent antibacterial activity, with a maximum inhibition zone of 24.4 ± 0.4 mm at 20 μg/disk, MIC values of 6.25-25 μg/mL, and MBC values of 12.5-50 μg/mL. Additionally, biofilm formation was inhibited by up to 92.1% at 250 μg/mL. Our mechanistic study confirmed that ZnO-NPs damage bacterial membranes and DNA, leading to the intracellular leakage of cell components that lead to bacterial cell lysis. The use of S. rebaudiana in ZnO-NP synthesis aligns with green chemistry principles, offering an eco-friendly alternative to conventional antibiotics and enhancing the bioactivity of ZnO-NPs, and may address the growing issue of antimicrobial resistance, thereby contributing to improved food safety and public health protection.

Green Nanotechnology: Naturally Sourced Nanoparticles as Antibiofilm and Antivirulence Agents Against Infectious Diseases

The escalating threat of infectious diseases, exacerbated by antimicrobial resistance (AMR) and biofilm formation, necessitates innovative therapeutic strategies. This review presents a comprehensive exploration of the potential of nanoparticles synthesized from natural sources, including plant extracts, microbial products, and marine compounds, as antimicrobial agents. These naturally derived nanoparticles demonstrated significant antibiofilm and antivirulence effects, with specific examples revealing their capacity to reduce biofilm mass by up to 78% and inhibit bacterial quorum sensing by 65%. The integration of bioactive compounds, such as polyphenols and chitosan, facilitates nanoparticle stability and enhances antimicrobial efficacy, while green synthesis protocols reduce environmental risks. Notably, the review identifies the potential of silver nanoparticles synthesized using green tea extracts, achieving 85% inhibition of polymicrobial growth in vitro. Despite these promising results, challenges such as standardization of synthesis protocols and scalability persist. This study underscores the transformative potential of leveraging naturally sourced nanoparticles as sustainable alternatives to conventional antimicrobials, offering quantitative insights for their future application in combating mono- and polymicrobial infections.

Acentric Order-Disorder Zn3Sb4CO6F6: Crystal Structure, Dye Degradation, Cr(VI) Removal, Antibacterial Activity, and Catalytic C-C Bond Formation

Acentric Zn3Sb4CO6F6 has been synthesized by a hydrothermal technique. Single crystal X-ray diffraction study reveals that it crystallizes in cubic symmetry with a = 8.1480 (5) Å and Z = 2 (I4̅3 m). The carbon atom has tetrahedral coordination by Sb, either as an ordered structure at the center of the tetrahedron or as a disordered structure with carbon displaced toward three Sb atoms; the latter model leads to more acceptable Sb-C interatomic distances. Zn3Sb4CO6F6 has been established as the first multifunctional [M-L-C-O-F] compound, with exceptional properties, i.e., photocatalyst, adsorbent, catalyst for organic reactions, and antibacterial agent. This compound successfully degraded 89.5% of 50 mg/L methylene blue dye under solar illumination. It was also proved to be a proficient adsorbent toward Cr(VI) removal with qmax of 47.18 mg/g. The antibacterial activity was investigated by "agar cup assay" against both Gram-positive and Gram-negative bacterial strains. Zn3Sb4CO6F6 also functions as an excellent catalyst for the solvent-free Knoevenagel condensation reaction, with more than 90% yield. Theoretical investigations further proved that Zn3Sb4CO6F6 exhibits a direct band gap energy of 1.76 eV, which is consistent with the experimental findings. The synthesized compound was also characterized through fourier transform infrared spectroscopy, powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and selected area electron diffraction study.

Development of Glutathione Hydrogel Carriers Containing Zinc Oxide Microparticles for Skin Regeneration Processes

Skin represents the largest organ in the human body, functioning as a protective barrier against environmental factors while playing a critical role in thermoregulation. Acne vulgaris is recognized as the most common dermatological condition affecting adolescents, and if left untreated, it can result in lasting skin damage and associated psychosocial challenges. This study aims to develop innovative polymeric biomaterials that could effectively support the treatment of acne vulgaris. The synthesis of these biomaterials involves the use of polyethylene glycol 6000, sodium alginate, and the antioxidant protein glutathione (GHS) to create polymeric hydrogels. These hydrogels were generated via a UV-mediated crosslinking process. To enhance the functional properties of the hydrogels, zinc oxide microparticles (ZnO), synthesized through a wet precipitation method, were incorporated into the formulations. Characterization of the ZnO was performed using Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), particle sizer analysis, and Scanning Electron Microscopy (SEM). Additionally, the bioactivity of the synthesized materials was evaluated through incubation in media simulating physiological body fluids. The cytotoxic effects of the biomaterials were assessed using an indirect test on mouse fibroblast (L929) cells, in accordance with ISO 10993-5 guidelines. The results of our research indicate that the developed biomaterials exhibit potential as a carrier for active substances, contributing positively to the treatment of acne vulgaris and potentially improving overall skin health.

Evaluation of Antibacterial Properties of Zinc Oxide Nanoparticles Against Bacteria Isolated from Animal Wounds

Background/Objectives: This research aimed to determine the efficacy of metallic oxide nanoparticles, especially zinc oxide nanoparticles (ZnO-NPs), in inhibiting a wide range of bacteria isolated from animal wounds, indicating their potential as alternative antimicrobial therapies in veterinary medicine. Method: The disc diffusion technique, broth microdilution technique, and time-kill kinetic assay were performed to determine the antibacterial activity of the ZnO-NPs. Results: Transmission electron microscopy (TEM) and scanning electron microscopy (SEM showed that the ZnO-NPs were spherical and polygonal with sizes ranging from 50 to 100 nm, while DLS (NanoSizer) measured an average size of 512.3 to 535.7 nm with a polydispersity index (PDI) of 0.50 to 0.63 due to particle size agglomeration. The ZnO-NPs exhibited antibacterial activity against several bacterial strains isolated from animal wounds, including Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae, with inhibition zones ranging from 10.0 to 24.5 mm, average MIC values ranging from 1.87 ± 0.36 to 3.12 ± 0.62 mg/mL, and an optimum inhibitory effect against Staphylococcus spp. The time-kill kinetic assay revealed that the Zn-ONPs eradicated Staphylococcus spp. and Klebsiella pneumoniae, as well as Escherichia coli and Pseudomonas aeruginosa (99.9% or 3-log10 reduction), within 30 min of treatment. They also demonstrated a varying degree of antibiofilm formation activity, as indicated by the percentage reduction in biofilm formation compared to the untreated biofilm-forming bacterial strains. Conclusion: ZnO-NPs effectively inhibit bacterial growth and biofilm formation in animal wound isolates.

Biosynthesis of a range of ZnO nanoparticles utilising Salvia hispanica L. seed extract and evaluation of their bioactivity

Zinc deficiency precipitates considerable health problems in developing countries, affecting development, growth, and immunological function. The main issue is that zinc exhibits limited bioavailability in diets, sometimes compounded by the high concentration of phytate molecules in staple foods, which impedes zinc absorption. Nanoparticles offer a promising approach to improve zinc bioavailability and address deficiency through the application of advanced agricultural techniques. The study introduces a novel method for synthesizing Zinc oxide (ZnO) biometallic nanoparticles by employing aqueous extracts of Salvia hispanica L. (Chia seed) as a reducing and capping agent in an environmentally sustainable way. Their active phytoconstituents acted as a stabilising agent and facilitated the conversion of ionic zinc (Zn2+) into elemental zinc. The study synthesized the diverse forms of zinc oxide nanoparticles (NP-α, NP-β, NP-γ, NP-δ, NP-ε, and NP-η) utilising various molar concentrations (0.5mM, 1.0mM, 3.0mM, 5.0mM, 7.0mM, and 9.0mM) of a precursor solution, zinc nitrate [(ZnNO3)2]. The synthesized NPs were evaluated using UV-Vis spectroscopy, FTIR spectroscopy, XRD, SEM, EDX, TEM, SAED, and HR-TEM methods to determine their characteristics. The standard particle size varies from 40 to 80 nm, exhibiting a consistent hexagonal morphology and a polydispersed characteristic with minimal size fluctuation. The molarity substantially influenced the shape of NPs, particularly concerning their size and surface area. An in vitro evaluation was performed to investigate the antibacterial activity against Staphylococcus aureus and the possible degradation of the hazardous dye Congo red. The particles exhibited antibacterial efficacy at a concentration of 40 ppm ZnO, antidiabetic qualities at 10 µl/ml ZnONPs, antioxidant activity at concentrations ranging from 100 to 900 µl/ml showing 89.47 ± 0.022 µg AAE/mg, maximum activity with total antioxidant capacity (TAC), and dye degradation potential at a concentration of 50 mg ZnONPs, revealed 50.78% CR degradation after 90 min of irradiation. Additionally, it had significant inhibitory effects on the enzymes α-amylase (72.93%) and α-glucosidase (60.48%) by ZnONP-η. The efficacy of dye degradation with synthesized nanoparticles seems to enhance with increased particle sizes and reduced specific surface areas. The antioxidant, antidiabetic, and catalytic capabilities improved with an increase in particle size. Nevertheless, it was found that an increase in particle size corresponded with a substantial reduction in antibacterial activity. The study presents an efficient approach for the eco-friendly synthesis of ZnONPs, highlighting their significant potential for many biological applications.

Rat model evaluation for healing-promoting effectiveness and antimicrobial activity of electron beam synthesized (polyvinyl alcohol-pectin)- silver doped zinc oxide hydrogel dressings enriched with lavender oil

Ag/ZnO NPs and lavender oil (LVO) were incorporated into (polyvinyl alcohol/pectin) (PVA/Pet) dressings using electron beam irradiation technology. The Ag/ZnO NPs were prepared using the precipitation method and characterized using XRD, FTIR, and EDX techniques. TEM micrograph shows their spherical appearance with an average size of around 27.4 nm. The increase in the (PVA: Pet) feed solution concentration up to 30% enhances the gel content to 92%. The swelling degree reaches 1674% using 80 wt% pectin content. Meanwhile, increasing the irradiation dose up to 45 kGy increases the gel fraction and negatively affects the swelling capabilities. Incorporating Ag/ZnO NPs and LVO slightly decreased the gel fraction, the swelling degree, and the dressing's porosity reached 87%. In pseudo extracellular fluids, dressings with 10% LVO demonstrate 419% swelling capacities, and their WVTR reaches 271.1 g/m2h. Dressings show biocompatibility, antimicrobial potential, and excellent wound healing capacity towards the excisional wound model in rats, as confirmed by the histological and biochemical results. LVO-(PVA/Pet)-Ag/ZnO dressings may accelerate tissue granulation and remodeling by replacing lost collagen and cause the wound to constrict by upregulating markers associated with wound healing so that it can be recommended as a wound healing candidate.

Growth of ZnO Nanoparticles Using Microwave Hydrothermal Method-Search for Defect-Free Particles

This study investigated the influence of chemical reagent selection on the properties of ZnO nanoparticles synthesized using the microwave-assisted hydrothermal method to control the intensities of near-band-edge (NBE) and defect-related deep-level (DLE) emissions. Two zinc precursors-zinc nitrate and zinc chloride-along with three different precipitating agents (NaOH, KOH, and NH4OH) were used. ZnO nanoparticles from the ZnCl2 precursor exhibited two orders of magnitude higher NBE/DLE intensity ratio compared to those obtained from zinc nitrate characterized by a higher contribution from defect-related emissions. Chlorine ions in ZnO nanoparticles play a key role in passivating defects by forming V0-Cl2 complexes, quenching luminescence associated with oxygen vacancies (V0). Thermal treatment in a nitrogen atmosphere enhanced defect-related luminescence, possibly due to chlorine atom diffusion. This study highlights a successful synthesis of ZnO nanoparticles with low defect-related luminescence (DLE) achieved via the microwave-assisted hydrothermal method, a result rarely reported in the literature. The results emphasize the importance of reagent selection in controlling the morphology and optical properties, especially the defect density of ZnO nanoparticles. Optimizing these properties is crucial for biomedical applications such as bioimaging, antibacterial treatments, and photocatalysis.

Eco-friendly zinc oxide nanoparticle biosynthesis powered by probiotic bacteria

The rapid advancement of nanotechnology, particularly in the realm of pharmaceutical sciences, has significantly transformed the potential for treating life-threatening diseases. A pivotal aspect of this evolution is the emergence of "green nanotechnology," which emphasizes the environmentally sustainable synthesis of raw materials through biological processes. This review focuses on the biological synthesis and application of zinc oxide (ZnO) nanoparticles (NPs) from probiotic bacteria, particularly those sourced from wastewater. Microorganisms from wastewater tolerate harmful elements and enzymatically convert toxic heavy metals into eco-friendly materials. These probiotic bacteria are instrumental in the synthesis of ZnO NPs and exhibit remarkable antimicrobial properties with diverse industrial applications. As the challenge of drug-resistant pathogens escalates, innovative strategies for combating microbial infections are essential. This review explores the intersection of nanotechnology, microbiology, and antibacterial resistance, highlighting the importance of selecting suitable probiotic bacteria for synthesizing ZnO NPs with potent antibacterial activity. Additionally, the review addresses the biofunctionalization of NPs and their applications in environmental remediation and therapeutic innovations, including wound healing, antibacterial, and anticancer treatments. Eco-friendly NP synthesis relies on the identification of these suitable microbial "nano-factories." Targeting probiotic bacteria from wastewater can uncover new microbial NP synthesis capabilities, advancing environmentally friendly NP production methods. KEY POINTS: • Innovative strategies are needed to combat drug-resistant pathogens like MRSA. • Wastewater-derived probiotic bacteria are an eco-friendly method for ZnO synthesis. • ZnO NPs show significant antimicrobial activity against various pathogens.

Enhancing Mechanical and Antibacterial Performance of Tire Waste/Epoxidized Natural Rubber Blends Using Modified Zinc Oxide-Silica

This study investigates the synergistic effects of incorporating modified zinc oxide-silica (ZnO-SiO2) into tire waste (TW) and epoxidized natural rubber (ENR) blends, with a focus on crosslinking dynamics, mechanical reinforcement, and antibacterial activity. The addition of ZnO-SiO2 significantly enhanced crosslink density, as evidenced by increased torque and accelerated cure rates. An optimal concentration of 10 phr was found to yield the highest performance. This optimal balance between chemical activation and mechanical reinforcement resulted in exceptional tensile properties, including notable improvements in Young's modulus, tensile strength, and strain-induced crystallization (SIC). These enhancements were attributed to the strong interactions between ENR molecular chains and SiO2 surfaces. However, excessive ZnO-SiO2 concentrations caused filler agglomeration, which reduced both mechanical and antibacterial performances. An antibacterial analysis revealed a remarkable 99.9% bacterial reduction at 10 phr ZnO-SiO2, attributed to the Zn2+ ion release and reactive oxygen species (ROS) generation, with sustained activity even after thermal aging. This durability underscores the composites' potential for long-term applications. The findings establish ZnO-SiO2 as a dual-functional filler that optimizes crosslinking, enhances mechanical properties, and provides durable antibacterial efficiency. These results highlight the potential of TW/ENR blends while offering critical insights into mitigating filler agglomeration to improve overall material performance.

Enhancing the efficacy of zinc oxide nanoparticles by beta-carotene conjugation for improved anti-microbial and anti-tumor therapy for dental application

Zinc oxide NPs (ZnO NPs) are notable in nanomedicine for their exceptional physicochemical and biological properties. This study synthesizes and characterizes beta-carotene-coated ZnO NPs (BT-ZnO NPs) for potential anti-cancer and antimicrobial applications, demonstrating significant efficacy against dental pathogens and oral cancer cells. Scanning Electron Microscopy, EDAX, UV, FTIR, XRD, and Zeta potential analysis of prepared BT-ZnO NPs revealed uniform flower-like crystalline structures with intricate morphology and an average particle size of 38.06 nm. FTIR spectra identified various functional groups, suggesting a complex organic compound coated with ZnO NPs. Zeta potential measurements showed pH-dependent surface charge variations, which are crucial for understanding colloidal stability. The antimicrobial activity was potent against dental pathogens, with minimum inhibitory concentration (MIC) values of 50 µg/mL highlighting significant inhibition. Molecular docking studies demonstrated strong binding affinities of BT to key receptor proteins of dental pathogens. BT-ZnO NPs exhibited notable antioxidant activity of 68%, comparable to ascorbic acid, and significant anti-inflammatory effects of 75.1% at 100 µg/mL. Cytotoxicity assays indicated a concentration-dependent suppression of KB cell proliferation, decreasing cell viability to 37.19%, and gene expression studies showed elevated P53 expression, suggesting a strong apoptotic response. These multifaceted properties underscore the potential of BT-ZnO NPs as an integrated therapeutic approach for dental healthcare and oncology.

ZnO-Rutin nanostructure as a potent antibiofilm agent against Pseudomonasaeruginosa

Pseudomonas aeruginosa is a common human pathogen that is resistant to multiple antibiotics due to its ability to form biofilms. Developing novel nanoformulations capable of inhibiting and removing biofilms offers a promising solution for controlling biofilm-related infections. In this study, we investigated the anti-biofilm activity of rutin-conjugated ZnO nanoparticles (ZnO-Rutin NPs) in pathogenic strains of P. aeruginosa. The synthesized ZnO-Rutin NPs had amorphous shapes with sizes ranging from 14 to 100 nm. The broth microdilution assay revealed that ZnO-Rutin NPs, with an MIC value of 2 mg/mL, exhibit greater antimicrobial activity than ZnO NPs and rutin alone. Based on crystal violet staining, the biofilm inhibition rate by ½ MIC of the conjugated nanoparticles was recorded at above 90 %. The significant reduction in exopolysaccharide (62.75-66.37 %) and alginate (38.3-57.61 %) levels, as well as the formation of thin biofilms in the ZnO-Rutin NP-treated group, confirmed the anti-biofilm potential of these nanoparticles. Additionally, a significant decrease in the metabolic activity and viable cells of mature biofilms was observed after exposure to the conjugated nanoparticles. Furthermore, ZnO-Rutin NPs considerably attenuated the expression of the Las-Rhl quorum-sensing transcriptional regulator genes (lasR and rhlR) in P. aeruginosa by 0.39-0.40 and 0.25-0.42 folds, respectively. This work demonstrated that ZnO-Rutin NPs are remarkably capable of inhibiting the initial stage of biofilm formation and eradicating mature biofilms, suggesting they could be a useful agent for treating P. aeruginosa biofilm-related infections.

Application of green silver nano-particles as anti-bacterial and photo-catalytic degradation of azo dye in wastewater

Ensuring everyone enjoys healthy lifestyles and well-being at all ages, Progress has been made in increasing access to clean water and sanitation facilities and reducing the spread of epidemics and diseases. The synthesis of nano-particles (NPs) by using microalgae is a new nanobiotechnology due to the use of the biomolecular (corona) of microalgae as a capping and reducing agent for NP creation. This investigation explores the capacity of a distinct indigenous microalgal strain to synthesize silver nano-particles (AgNPs), as well as its effectiveness against multi-drug resistant (MDR) bacteria and its ability to degrade Azo dye (Methyl Red) in wastewater. An extract of Spirulina platensis was obtained from a local source to synthesize silver nano-particles (AgNPs). The synthesized AgNPs were subsequently subjected to characterization utilizing several analytical methods, namely UV-visible spectroscopy, scanning electron microscopy (SEM), X-ray diffraction, and Fourier transform infrared spectroscopy (FTIR analysis). Subsequently, the disc diffusion method assessed their anti-bacterial efficacy against multi-drug resistant (MDR) bacteria and their ability to degrade Azo dye (Methyl Red) in wastewater. The nano-particles produced through biological synthesis exhibited a prominent peak in the UV-visible spectrum at a wavelength of 430 nm. Furthermore, these nano-particles were determined to possess a crystalline nature, with an average size of 28.72 nm and a distinctive star-like shape. The synthesized silver nano-particles (AgNPs) exhibited a dose-dependent anti-bacterial effect against some clinical bacterial isolates as multi-drug resistant (MDR), including Gram- ve bacteria such as Pseudomonas aeruginosa and Escherichia coli, as well as Gram+ ve bacteria like Staphylococcus aureus and Streptococcus pneumoniae. The action can be ascribed to the unique biological and physicochemical features of AgNPs, which facilitate the disruption of bacterial cell membranes. The UV-visible analysis solution after the introduction of AgNPs indicated that the decrease in the absorbance peak of methyl red was attributed to the existence of silver nano-particles. Metal nano-particles can be synthesized using environmentally friendly processes and hold great potential for combating multi-drug resistant bacteria and degrading Azo dyes. Silver nano-particles (AgNPs) are synthesized with an extract derived from the algae Spirulina platensis, which is a sustainable and eco-friendly alternative.

The Impact of Nickel-Zinc Ferrite Nanoparticles on the Mechanical and Barrier Properties of Green-Synthesized Chitosan Films Produced Using Natural Juices

A trend has been established concerning the research and development of various green and biodegradable plastics for multi-purpose applications, aiming to replace petroleum-based plastics. Herein, we report the synthesis of chitosan (CH) films using lemon juice; these were reinforced with NiZnFe2O4 nanoparticles (NiZnFe2O4 NPs) to obtain improved mechanical and barrier properties, facilitating their future application as sustainable, corrosion-resistant coatings for medical instruments. The synthesized NiZnFe2O4 NPs had a crystallite size of ~29 nm. Reinforcement with the nanoparticles in bio-sourced chitosan films was conducted at two concentrations: 1% and 2%. The mechanical strength of the CH film was found to be 1.52 MPa, while the 2% NiZnFe2O4 NP-containing films showed stress-bearing potential of 1.04 MPa with a larger strain value, confirming the elastic nature of the films. Furthermore, the % elongation was directly proportional to the NP concentration, with the highest value of 36.833% obtained for the 2% NP-containing films. The CH films presented improved barrier properties with the introduction of the NiZnFe2O4 NPs, making them promising candidates for coatings in medical instruments; this could protect such instruments from corrosion under controlled conditions. This approach not only broadens the application range of biopolymeric films but also aligns with global sustainability goals, serving to reduce the reliance on non-renewable corrosion-resistant coatings.

Green Synthesis of Zinc Oxide Nanoparticles: Preparation, Characterization, and Biomedical Applications - A Review

Over the last decade, biomedical nanomaterials have garnered significant attention due to their remarkable biological properties and diverse applications in biomedicine. Metal oxide nanoparticles (NPs) are particularly notable for their wide range of medicinal uses, including antibacterial, anticancer, biosensing, cell imaging, and drug/gene delivery. Among these, zinc oxide (ZnO) NPs stand out for their versatility and effectiveness. Recently, ZnO NPs have become a primary material in various sectors, such as pharmaceutical, cosmetic, antimicrobials, construction, textile, and automotive industries. ZnO NPs can generate reactive oxygen species and induce cellular apoptosis, thus underpinning their potent anticancer and antibacterial properties. To meet the growing demand, numerous synthetic approaches have been developed to produce ZnO NPs. However, traditional manufacturing processes often involve significant economic and environmental costs, prompting a search for more sustainable alternatives. Intriguingly, biological synthesis methods utilizing plants, plant extracts, or microorganisms have emerged as ideal for producing ZnO NPs. These green production techniques offer numerous medicinal, economic, environmental, and health benefits. This review highlights the latest advancements in the green synthesis of ZnO NPs and their biomedical applications, showcasing their potential to revolutionize the field with eco-friendly and cost-effective solutions.

A combined therapy of meropenem-ZnO nanoparticles efficiently eliminates carbapenem-resistant Klebsiella pneumoniae biofilms, with reduced nephrotoxicity (in vitro)

In response to the World Health Organization's research agenda of antimicrobial resistance in human health, this study appraised the antibacterial and antibiofilm synergistic activity of meropenem and ZnO nanoparticles (ZnO-NPs) combination against carbapenem-resistant Klebsiella pneumoniae (CRKP). The minimum inhibitory concentration (MIC) of meropenem in combination was found to be ~1/12 of its MIC alone. The results of microtiter dilution assay showed that the combination was more efficient in reducing the biofilm biomass than meropenem alone or ZnO-NPs alone. The scanning-electron-microscopy micrographs elucidated that the combination of meropenem with ZnO-NPs has significantly enhanced its competence in eradicating the preformed biofilms of CRKP strains. In addition, the relative gene expression results showed that the combination compared to the meropenem alone and ZnO-NPs alone eloquently down-regulated the expression of biofilm genes (mrkA, fimA, and ecpA). Besides, the MTT-assay demonstrated that the combination has limited cytotoxicity against Vero-cells (in vitro). Overall, this study represents an efficient safe enhancement of meropenem to tackle the growing health threat of CRKP and carbapenem-resistant Enterobacterals prevalence.

High-frequency ultrasound modulation of Zn2+ release from nanoclay supported ZnO antibacterial composites

Bacterial infections pose considerable health risks, emphasising the critical need for effective and biocompatible antibacterial drugs. Considerably, we developed an efficient antimicrobial system incorporating the combined potential of high-frequency ultrasound and antimicrobial drugs against bacterial infections. A ZnO-kaolinite (Kaol) composite with antibacterial properties was synthesised by growing ZnO on the Kaol nano-clay surface using the co-precipitation method. High-frequency ultrasound efficiently promotes the release of Zn2+, which enhances the antibacterial properties. Furthermore, in-depth in vitro antibacterial studies and bacterial live/dead staining experiments validate the exceptionally high antibacterial performance of the composite. Therefore, owing to the synergistic effects of high-frequency ultrasound and antibacterial properties, the as-prepared novel antibacterial composite is a promising potential substitute for conventional antibacterial agents.

ZnO nanoparticles induced biofilm formation in Klebsiella pneumoniae and Staphylococcus aureus at sub-inhibitory concentrations

Biofilm formation by the pathogenic bacteria generates a serious threat to the public health as it can increase the virulence potential, resistance to drugs, and escape from the host immune response mechanisms. Among the environmental factors that influence the biofilm formation, there are only limited reports available on the role of antimicrobial agents. During the antimicrobial drug administration or application for any purpose, the microbial population can expect to get exposed to the sub-minimum inhibitory concentration (sub-MIC) of the drug which will have an unprecedented impact on microbial responses. Hence, the study has been conducted to investigate the effects of sub-MIC levels of zinc oxide nanoparticles (ZnO NPs) on the biofilm formation of Klebsiella pneumoniae and Staphylococcus aureus. Here, the selected bacteria were primarily screened for the biofilm formation by using the Congo red agar method, and their susceptibility to ZnO NPs was also evaluated. Quantitative difference in biofilm formation by the selected organisms in the presence of ZnO NPs at the sub-MIC level was further carried out by using the microtiter plate-crystal violet assay. Further, the samples were subjected to atomic force microscopy (AFM) analysis to evaluate the properties and pattern of the biofilm modulated under the experimental conditions used. From these, the organisms treated with sub-MIC levels of ZnO NPs were found to have enhanced biofilm formation when compared with the untreated sample. Also, no microbial growth could be observed for the samples treated with the minimum inhibitory concentration (MIC) of ZnO NPs. The results observed in the study provide key insights into the impact of nanomaterials on clinically important microorganisms which demands critical thinking on the antimicrobial use of nanomaterials.

Bioactive ECM-mimicking nerve guidance conduit for enhancing peripheral nerve repair

Extensive research efforts are being directed towards identifying alternatives to autografts for the treatment of peripheral nerve injuries (PNIs) with engineered nerve conduits (NGCs) identified as having potential for PNI patients. These NGCs, however, may not fulfill the necessary criteria for a successful transplant, such as sufficient mechanical structural support and functionalization. To address the aforementioned limitations of NGCs, the present investigation explored the development of double cross-linked hydrogels (o-CSMA-E) that integrate the biocompatibility of porcine tendon extracellular matrix (ECM) with the antimicrobial and conductive properties of methacrylated quaternary chitosan. The hydrogels had matrices that could promote the growth of axons and the transmission of neural signals. The hydrogels were subsequently incorporated into a nanofibrous PLLA-ZnO sheath scaffold (ZnO@PLLA) to emulate the natural nerve structure, guiding cell growth and facilitating nerve regeneration. The collaboration of core and sheath materials in ZnO@PLLA/o-CSMA-E nerve guidance conduits resulted in enhanced migration of Schwann cells, formation of myelin sheaths, and improved locomotion performance in rats with sciatic nerve defects when in vivo studies were undertaken. Notably, the in vivo studies demonstrated the similarity between the newly developed engineered NGCs and autologous transplants, with the newly engineered NGCs possessing the potential to promote functional recovery by mimicking the tubular structure and ECM of nerves.

Neuroprotective properties of zinc oxide nanoparticles: therapeutic implications for Parkinson's disease

Parkinson's disease (PD) significantly affects millions of people worldwide due to the progressive degeneration of dopamine-producing neurons in the substantia nigra pars compacta. Despite extensive research efforts, effective treatments that can halt or reverse the progression of PD remain elusive. In recent years, nanotechnology has emerged as a promising new avenue for addressing this challenge, with zinc oxide nanoparticles (ZnO-NPs) standing out for their extensive therapeutic potential. ZnO-NPs have shown remarkable promise in neuroprotection through several key mechanisms. The multifaceted properties of ZnO-NPs suggest that they could play a crucial role in intervening across various fundamental mechanisms implicated in PD. By targeting these mechanisms, ZnO-NPs offer new insights and potential strategies for managing and treating PD. This review aims to provide a thorough examination of the molecular mechanisms through which ZnO-NPs exert their neuroprotective effects. It highlights their potential as innovative therapeutic agents for PD and outlines directions for future research to explore and harness their full capabilities.

Synthesis, Crystal Structures, Antimicrobial Activity, and Acute Toxicity Evaluation of Chiral Zn(II) Schiff Base Complexes

Four mononuclear bioefficient zinc coordination complexes [Zn(NN)3](ClO4)2 (A-D) involving chiral bidentate Schiff base ligands have been synthesized and characterized by IR, 1H, and 13C NMR spectroscopy and mass spectrometry. X-ray crystal structures of three of the zinc complexes revealed that the zinc metal ion is hexacoordinated, exhibiting a distorted octahedral geometry where both the nitrogen atoms (NN = pyridyl and imine) of imines are coordinated to the central zinc ion. The isolated zinc complexes were evaluated for their antimicrobial activity in vitro against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, displaying varying levels of growth inhibition. An acute toxicity test conducted using Artemia salina and Swiss albino mice showed that the zinc complexes A-D were non-toxic towards A. salina at concentrations below 414, 564, 350, and 385 µM, respectively, and did not affect liver biochemical parameters, although pyknosis was induced in hepatocytes of the treated mice.

Green Synthesis of Al-ZnO Nanoparticles Using Cucumis maderaspatanus Plant Extracts: Analysis of Structural, Antioxidant, and Antibacterial Activities

Nanoparticles derived from biological sources are currently garnering significant interest due to their diverse range of potential applications. The purpose of the study was to synthesize Al-doped nanoparticles of zinc oxide (ZnO) from leaf extracts of Cucumis maderaspatanus and assess their antioxidant and antimicrobial activity using some bacterial and fungal strains. These nanoparticles were analyzed using X-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), and thermogravimetric analysis/differential thermal analysis (TG-DTA). The average crystalline size was determined to be 25 nm, as evidenced by the XRD analysis. In the UV-vis spectrum, the absorption band was observed around 351 nm. It was discovered that the Al-ZnO nanoparticles had a bandgap of 3.25 eV using the Tauc relation. Furthermore, by FTIR measurement, the presence of the OH group, C=C bending of the alkene group, and C=O stretching was confirmed. The SEM analysis revealed that the nanoparticles were distributed uniformly throughout the sample. The EDAX spectrum clearly confirmed the presence of Zn, Al, and O elements in the Al-ZnO nanoparticles. The TEM results also indicated that the green synthesized Al-ZnO nanoparticles displayed hexagonal shapes with an average size of 25 nm. The doping of aluminum may enhance the thermal stability of the ZnO by altering the crystal structure or phase composition. The observed changes in TG, DTA, and DTG curves reflect the impact of aluminum doping on the structural and thermal properties of ZnO nanoparticles. The antibacterial activity of the Al-ZnO nanoparticles using the agar diffusion method showed that the maximum zone of inhibition has been noticed against organisms of Gram-positive S. aureus compared with Gram-negative E. coli. Moreover, antifungal activity using the agar cup method showed that the maximum zone of inhibition was observed on Aspergilus flavus, followed by Candida albicans. Al-doping nanoparticles increases the number of charge carriers, which can enhance the generation of reactive oxygen species (ROS) under UV light exposure. These ROS are known to possess strong antimicrobial properties. Al-doping can improve the crystallinity of ZnO, resulting in a larger surface area that facilitates more interaction with microbial cells. The structural and biological characteristics of Al-ZnO nanoparticles might be responsible for the enhanced antibacterial activity exhibited in the antibacterial studies. Al-ZnO nanoparticles with Cucumis maderaspatanus leaf extract produced via the green synthesis methods have remarkable antioxidant activity by scavenging free radicals against DPPH radicals, according to these results.

Facile assembly of flexible humidity sensors based on nanostructured graphite/zinc oxide-coated cellulose fibrous frameworks for human healthcare

The development of flexible, cost-effective, highly efficient, and reliable humidity monitoring sensors is in high demand owing to their wide-range of applications in industrial domains. In this study, a humidity sensor was fabricated based on graphite/zinc oxide nanoparticle (G/ZnO-NP)-coated cellulose paper. A bar device was designed using computer software, and its sketch was printed on cellulose paper, with graphite bars then added using the pencil-drawing method, and then ZnO-NP paste was coated on the graphite patterns. Scanning electron microscopy and X-ray diffraction analysis were used to respectively inspect the morphological and structural features of the samples. For sensor fabrication, copper wires were attached to the electrodes using copper tape. The fabricated device was placed into a chamber with varying relative humidity (RH) levels of 11%, 24%, 43%, 62%, 84%, and 97%, controlled using the salt solutions inside the chamber. The response of the sensor was recorded in terms of the change in resistance of the device upon exposure to different humidity environments. The sensor delivered a response time as short as 4.31 s for the 24% RH condition, and a recovery time as short as 10.05 s for 43% RH. Moreover, the sensor exhibited a sensitivity of 717% for the 97% RH condition. The sensor was also evaluated for human breath monitoring, showing distinctive responses for inhalation and exhalation.

Eco-friendly synthesis of betanin-conjugated zinc oxide nanoparticles: antimicrobial efficacy and apoptotic pathway activation in oral cancer cells

BACKGROUND

Phytochemical-based synthesis of nanoparticles (NPs) is an eco-friendly approach with various biomedical applications. Betanin, a natural pigment in beetroot, has antioxidant, anti-inflammatory, and antimicrobial properties. When conjugated with zinc oxide nanoparticles (ZnO NPs), these properties are enhanced. This study aimed to synthesize betanin-ZnO nanoparticles (BE-ZnO-NPs) and evaluate their biological potential.

METHODS

BE-ZnO-NPs were synthesized and characterized using UV-Visible spectroscopy, FTIR, FE-SEM, HR-TEM, EDX, XRD, DLS, and zeta potential analysis. In silico studies assessed interactions with oral pathogen proteins, and antibacterial activity was tested against Enterococcus faecalis, Candida albicans, Staphylococcus aureus and Streptococcus mutans. Antioxidant potential and cytotoxicity on KB cells were evaluated through scavenging assays, MTT assay, and qRT-PCR.

RESULTS

Betanin synthesized ZnO NPs UV-Vis results showed surface plasmon resonance at 388 nm, and FTIR confirmed betanin role as a capping agent. FE-SEM and TEM revealed particles of 37 nm. EDX confirmed zinc content, and XRD showed a hexagonal structure. Zeta potential was - 3.3 mV, and DLS indicated a size of 38.73 nm. In silico analysis showed strong binding to E. faecalis (- 8.0 Kcal/mol). BE-ZnO-NPs demonstrated antibacterial activity at 100 µg/mL, with inhibition zones of 18 ± 0.14 mm for E. faecalis and 14 ± 0.18 mm for S. mutans. In contrast, BE demonstrated antibacterial activity at 100 µg/mL, with zone of inhibition of 10.6 ± 0.14 mm for E. faecalisand 11.4 ± 0.18 mm for S. mutans.Antioxidant assays revealed dose-dependent scavenging activity. Cytotoxicity showed an IC50 of 24.29 µg/mL, with qRT-PCR indicating apoptosis through the BCL2/BAX/P53 pathway.

CONCLUSIONS

BE-ZnO-NPs exhibited significant antibacterial and antioxidant activities and demonstrated the ability to induce apoptosis in oral cancer cells via the BCL-2/BAX/P53 signalling pathway. These findings highlight the potential of BE-ZnO-NPs as promising antimicrobial agents for tooth infections and as therapeutic agents for oral tumour treatment.

Gamma-irradiated copper-based metal organic framework nanocomposites for photocatalytic degradation of water pollutants and disinfection of some pathogenic bacteria and fungi

BACKGROUND

Although there are many uses for metal-organic framework (MOF) based nanocomposites, research shows that these materials have received a lot of interest in the field of water treatment, namely in the photodegradation of water contaminants, and disinfection of some pathogenic bacteria and fungi. This is brought on by excessive water pollution, a lack of available water, low-quality drinking water, and the emergence of persistent micro-pollutants in water bodies. Photocatalytic methods may be used to remove most water contaminants, and pathogenic microbes, and MOF is an excellent modifying and supporting material for photocatalytic degradation.

METHODS

This work involved the fabrication of a unique Cu-MOF based nanocomposite that was exposed to gamma radiation. The nanocomposite was subsequently employed for photocatalytic degradation and as an antimicrobial agent against certain harmful bacteria and fungi. The produced Cu-MOf nanocomposite was identified by XRD, SEM, and EDX. Growth curve analysis, UV lighting impact, and antibiofilm potential have been carried out to check antimicrobial potential. Additionally, the membrane leakage test was used to determine the mechanism of the antimicrobial action. In an experimental investigation of photocatalytic activity, a 50 mL aqueous solution including 10.0 ppm of Rhodamine B (RB) was used to solubilize 10 mg of Cu-MOF. It has been investigated how pH and starting concentration affect RB elimination by Cu-MOF. Ultimately, RB elimination mechanism and kinetic investigations have been carried out.

RESULTS

SEM images from the characterization techniques demonstrated the fact that the Cu-MOF was synthesized effectively and exhibited the Cu-MOF layers' flake-like form. Uneven clusters of rods make up each stratum. The primary peaks in the Cu-MOF's diffraction pattern were found at 2θ values of 8.75◦, 14.83◦, 17.75◦, 21.04◦, 22.17◦, 23.31◦, 25.41◦, and 26.38◦, according to the XRD data. After 135 min of UV irradiation, only 8% of RB had undergone photolytic destruction. On the other hand, the elimination resulting from adsorption during a 30-min period without light was around 16%. Conversely, after 135 min, Cu-MOF's photocatalytic breakdown of RB with UV light reached 81.3%. At pH 9.0, the greatest removal of RB at equilibrium was found, and when the amount of photocatalyst rose from 5 to 20 mg, the removal efficiency improved as well. The most sensitive organism to the synthesized Cu-MOF, according to antimicrobial data, was Candida albicans, with a documented MIC value of 62.5 µg mL-1 and antibacterial ZOI as 32.5 mm after 1000 ppm treatment. Cu-MOF also showed the same MIC (62.5 µg mL-1) values against Staphylococcus aureus and Escherichia coli, and 35.0 and 32.0 mm ZOI after 1000 ppm treatment, respectively. Ultimately, it was found that Cu-MOF (1000 µg/mL) after having undergone gamma irradiation (100.0 kGy) was more effective against S. aureus (42.5 mm ZOI) and E. coli (38.0 mm ZOI).

CONCLUSION

From the obtained results, the synthesized MOF nanocomposites had promising catalytic degradation of RB dye and high antimicrobial potential which encouraging their use in wastewater treatment against some pathogenic microbes and polluted dyes. Due to the exceptional physicochemical characteristics of MOF nanocomposites, it is possible to create and modify photocatalytic nanocomposites in a way that improves their recovery, efficiency, and recyclability.

From e-waste to eco-sensors: synthesis of reduced graphene oxide/ZnO from discarded batteries for a rapid electrochemical bisphenol A sensor

Improper disposal of used dry cell batteries and the leaching of bisphenol A (BPA), a prevalent endocrine disruptor present in food packaging, into surface water pose a significant threat to both the environment and drinking water, threatening the sustainability of the ecosystem. Thus, it is imperative to manage detrimental e-waste and regularly monitor BPA using a sensitive and reliable technique. This study proposes a cost-effective reduced graphene oxide/zinc oxide (rGO/ZnO) nanohybrid, entirely synthesized from electronic waste, for electrochemically detecting BPA in an aqueous medium. Graphite and metallic Zn precursors obtained from discarded batteries were employed to synthesize rGO/ZnO. The successful characterization of the prepared rGO and rGO/ZnO nanohybrid was conducted through different state-of-the-art techniques. An rGO/ZnO-modified glassy carbon electrode (GCE) exhibited superior conductivity and a larger surface area. Voltammetric study at the rGO/ZnO-modified GCE successfully detected BPA in an aqueous medium, demonstrating a one-electron and proton pathway for BPA oxidation. The sensor demonstrated a linear response within the concentration range of 1-30 μM, with a limit of detection of 0.98 nM and sensitivity of 0.055 μA μM-1. The developed electrode could also detect BPA in real water samples with reasonable recovery. These findings imply that the developed sensor has the potential to be a sensitive, practical, and economical monitoring system for BPA in water.

Single-step hydrothermal synthesis of zinc oxide nanorods for potential use as nano-antibiotics without seeding or bases

The alarming global rise in antibiotic resistance, driven by the widespread overuse of traditional antibiotics, has created an urgent demand for new antimicrobial solutions. This study presents zinc oxide (ZnO) nanorods as a potential nano-antibiotic agent. ZnO nanorods, with a 2:3 aspect ratio, were synthesized using an efficient one-step hydrothermal method at a low temperature of 100°C, reducing the synthesis time to just 5 hours. The synthesized ZnO nanorods' morphology, structure, and composition were characterized using scanning electron microscopy, x-ray diffraction, and energy dispersive x-ray spectroscopy. The potent antimicrobial activity of these nanorods against common bacterial strains such as Escherichia coli, Bacillus subtilis, and Vibrio parahaemolyticus was examined through optical density at 600 nm (OD600) measurements and inhibition zone analysis, demonstrating substantial inhibition of bacterial growth. In particular, at a concentration of 5 mg/mL, ZnO nanorods achieved a 96% reduction of B. subtilis bacteria in OD600 and an impressive 99.87% reduction in culturing assays within one day, showcasing bactericidal efficiency on par with tetracycline at 0.003 mg/mL. Furthermore, a predictive model of bacterial growth was developed and validated, providing insights into the time-dependent bactericidal efficiency of the synthesized nanorods. These results highlight the potential of ZnO-based composites as a promising solution to combat antibiotic resistance, paving the way for next-generation antimicrobial materials.

Toxicity, Antibacterial, Antioxidant, Antidiabetic, and DNA Cleavage Effects of Dextran-Graft-Polyacrylamide/Zinc Oxide Nanosystems

Synthesis of metal oxide nanoparticles-polymer nanocomposites is an emerging strategy in nanotechnology to improve targeted delivery and reduce the toxicity of nanoparticles. In this study, we report biological effects of previously described hybrid nanocomposites containing dextran-graft-polyacrylamide/zinc oxide nanoparticles (D-PAA/ZnO NPs) prepared from zinc sulfate (D-PAA/ZnONPs(SO42-)) and zinc acetate (D-PAA/ZnONPs(-OAc)) focusing primarily on their antimicrobial activity. D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems were tested in a complex way to assess their antioxidant activity (DPPH assay), antidiabetic potential (α-amylase inhibition), DNA cleavage activity, antimicrobial, and antibiofilm activity. In addition, the toxicity of D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems against primary murine splenocytes was tested using MTT assay. The studied nanosystems inhibited E.coli growth. For all the investigated strains, minimum inhibitory concentrations (MICs) of D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) were in the range of 8 mg/L-128 mg/L and 16 mg/L-128 mg/L, respectively. The nanocomposites demonstrated effective antibiofilm properties as 94.27% and 86.43%. The compounds showed good antioxidant, anti-α-amylase, and DNA cleavage activities. D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems reduced cell viability and promoted cell death of primary murine spleen cells at concentrations higher than those that proved to be antibacterial indicating the presence of therapeutic window. D-PAA/ZnONPs(SO42-) and D-PAA/ZnONPs(-OAc) nanosystems show antioxidant, antidiabetic, DNA cleavage, antimicrobial, and antibiofilm activity against the background of good biocompatibility suggesting the presence of therapeutic potential, which should be further investigated in vivo.

Molecular mechanisms of zinc oxide nanoparticles neurotoxicity

Zinc oxide nanoparticles (ZnONPs) are widely used in industry and biomedicine. A growing body of evidence demonstrates that ZnONPs exposure may possess toxic effects to a variety of tissues, including brain. Therefore, the objective of the present review was to summarize existing evidence on neurotoxic effects of ZnONPs and discuss the underlying molecular mechanisms. The existing laboratory data demonstrate that both in laboratory rodents and other animals ZnONPs exposure results in a significant accumulation of Zn in brain and nervous tissues, especially following long-term exposure. As a result, overexposure to ZnONPs causes oxidative stress and cell death, both in neurons and glial cells, by induction of apoptosis, necrosis and ferroptosis. In addition, ZnONPs may induce neuroinflammation through the activation of nuclear factor kappa B (NF-κB), extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK), and lipoxygenase (LOX) signaling pathways. ZnONPs exposure is associated with altered cholinergic, dopaminergic, serotoninergic, as well as glutamatergic and γ-aminobutyric acid (GABA)-ergic neurotransmission, thus contributing to impaired neuronal signal transduction. Cytoskeletal alterations, as well as impaired autophagy and mitophagy also contribute to ZnONPs-induced brain damage. It has been posited that some of the adverse effects of ZnONPs in brain are mediated by altered microRNA expression and dysregulation of gut-brain axis. Furthermore, in vivo studies have demonstrated that ZnONPs exposure induced anxiety, motor and cognitive deficits, as well as adverse neurodevelopmental outcome. At the same time, the relevance of ZnONPs-induced neurotoxicity and its contribution to pathogenesis of neurological diseases in humans are still unclear. Further studies aimed at estimation of hazards of ZnONPs to human brain health and the underlying molecular mechanisms are warranted.

Synthesis and antibacterial activity of silver doped zinc sulfide/chitosan bionanocomposites: A new frontier in biomedical applications

Numerous microbial species have caused infectious diseases worldwide, which have become a social burden and a menace to the community. So, there is a need to develop antimicrobial materials and specialized materials for biomedical applications. In the present investigation, we report the simple synthesis, the physicochemical, and antibacterial activity of Silver doped zinc sulfide (ZnS: Ag) capped with Chitosan (CS) to produce ZnS: Ag/CS bionanocomposites (BNCs). The prepared BNCs was evaluated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX) mapping, and UV-Vis spectroscopy. According to the XRD results, ZnS: Ag/CS particles with semicrystalline chitosan/hexagonal ZnS phase structures and an average crystallite size in the range of 30-40 nm was formed. According to FESEM images, a spherical/hexagonal shape of ZnS: Ag particles embedded in the polymeric chitosan matrix. The colony counting method was employed to investigate the antibacterial activity on Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The results revealed that ZnS: Ag particles and ZnS: Ag/CS BNCs have stronger antibacterial activities than pure CS and ZnS. The reduction percentage of ZnS: Ag/CS BNCs against S. aureus and E. coli after 6 h of treatment was >99.9 % and 70 % respectively. These findings suggest that ZnS: Ag/CS BCs not only offer superior antimicrobial properties compared to individual ZnS and CS but also have great potential for advancing biomedical applications due to their enhanced antibacterial performance. The simplicity of the synthesis method and the use of non-toxic materials like chitosan make this a sustainable approach for developing antimicrobial agents, which is a key advantage of this study.

The antibacterial activity of the copper for Staphylococcus aureus 124 and Pseudomonas aeruginosa 18 depends on its state: metalized, chelated and ionic

The hypothesis that the antibacterial effect of copper depends on its state was tested. It was studied the antibacterial effect of copper applied to the fabric, copper in chelated and free (ionic) forms on the growth intensity of Staphylococcus aureus 124 and Pseudomonas aeruginosa 18 in the in vitro system after a single or "primary" contact. Classical microbiology methods were used. Copper was applied to the fabric by magnetron and arc planar discharge systems, and the culture of microalgae Dunaliella viridis, resistant to the action of high concentrations of copper, was used to obtain copper in chelated form. It was shown that a thin layer of copper (3 μm) applied to the fabric showed pronounced antibacterial activity against Staphylococcus (85 % compared to the antibiotic meropenem) and less pronounced activity against Pseudomonas, which is resistant to meropenem. Copper in ionic form inhibited the growth of Staphylococcus aureus 124 as well as the antibiotic, and also effectively inhibited the growth of Pseudomonas aeruginosa 18 i.e., copper ions did not have species specificity like the antibiotic. Components of Dunaliella viridis microalgae cells had weakly expressed antibacterial effect to these types of bacteria, and supplementary addition of copper sulfate to the biomass of microalgae led to an increase of their antibacterial activity and this is more pronounced for microalgae culture in which the ratio « chelated/ionic » forms of copper is shifted to the ionic form. It was shown that the antibacterial activity of microalgae biomass after the first introduction into the tested bacterial cultures depends on the amount of free or "weakly bound" with cell components copper ions. It is suggested that the antibacterial effect of fabric with a thin layer of copper may be determined by two mechanisms: the action of copper ions and mechano-bactericidal effects, while chelated forms of copper may have a prolonged effect on bacterial cultures.

Green synthesis of anethole-loaded zinc oxide nanoparticles enhances antibacterial strategies against pathogenic bacteria

The threat of antibiotic resistance is escalating, diminishing the effectiveness of numerous antibiotics due to the rapid development of resistant bacteria. In response, the use of green-synthesized nanoparticle, alone or combined with antimicrobial agents, appears promising. This study explores the effectiveness of zinc oxide nanoparticles (ZnONPs) synthesized using Loranthus cordifolius leaf extracts and subsequently coated with anethole. The fabrication of these nanoparticles was confirmed via UV-Vis, FTIR and TEM analyses, ensuring the nanoparticles were produced as intended. Utilizing a nanoprecipitation process that excludes evaporation and drying, a high drug loading capacity of 16.59% was accomplished. The encapsulation efficiency for anethole was recorded at 88.23 ± 4.98%. Antibacterial efficacy was assessed by com paring the green-synthesized ZnONPs (average size: 14.47 nm), anethole-loaded ZnONPs (average size: 14,75 nm), and commercially sourced ZnONPs. The ZnONPs with anethole demonstrated superior inhibition against all tested bacterial strains, including Gram-negative species like Pseudomonas aeruginosa and Escherichia coli, and Gram-positive species like Bacillus subtilis and Staphylococcus aureus, outperforming the commercially available ZnONPs. Additionally, anethole-coated ZnONPs showed the greatest inhibition of Gyr-B activity (IC50 = 0.78 ± 0.2 M), better than both green-synthesized and commercially available ZnONPs. These findings emphasize the enhanced antimicrobial properties of ZnONPs, particularly when combined with green synthesis and anethole loading, highlighting their potential in various biomedical applications.

Nanomedicines as a cutting-edge solution to combat antimicrobial resistance

Antimicrobial resistance (AMR) poses a critical threat to global public health, necessitating the development of novel strategies. AMR occurs when bacteria, viruses, fungi, and parasites evolve to resist antimicrobial drugs, making infections difficult to treat and increasing the risk of disease spread, severe illness, and death. Over 70% of infection-causing microorganisms are estimated to be resistant to one or several antimicrobial drugs. AMR mechanisms include efflux pumps, target modifications (e.g., mutations in penicillin-binding proteins (PBPs), ribosomal subunits, or DNA gyrase), drug hydrolysis by enzymes (e.g., β-lactamase), and membrane alterations that reduce the antibiotic's binding affinity and entry. Microbes also resist antimicrobials through peptidoglycan precursor modification, ribosomal subunit methylation, and alterations in metabolic enzymes. Rapid development of new strategies is essential to curb the spread of AMR and microbial infections. Nanomedicines, with their small size and unique physicochemical properties, offer a promising solution by overcoming drug resistance mechanisms such as reduced drug uptake, increased efflux, biofilm formation, and intracellular bacterial persistence. They enhance the therapeutic efficacy of antimicrobial agents, reduce toxicity, and tackle microbial resistance effectively. Various nanomaterials, including polymeric-based, lipid-based, metal nanoparticles, carbohydrate-derived, nucleic acid-based, and hydrogels, provide efficient solutions for AMR. This review addresses the epidemiology of microbial resistance, outlines key resistance mechanisms, and explores how nanomedicines overcome these barriers. In conclusion, nanomaterials represent a versatile and powerful approach to combating the current antimicrobial crisis.

Antimicrobial activity and nanoremediation of heavy metals using biosynthesized CS/GO/ZnO nanocomposite by Bacillus subtilis ATCC 6633 alone or immobilized in a macroporous cryogel

BACKGROUND

The world society is still suffering greatly from waterborne infections, with developing countries bearing most of the morbidity and death burden, especially concerning young children. Moreover, microbial resistance is one of the most prevalent global problems that extends the need for self-medication and the healing period, or it may be linked to treatment failure that results in further hospitalization, higher healthcare expenses, and higher mortality rates. Thus, innovative synthesis of new antimicrobial materials is required to preserve the environment and enhance human health.

RESULTS

The present study highlighted a simple and cost-effective approach to biosynthesize a chitosan/graphene oxide/zinc oxide nanocomposite (CS/GO/ZnO) alone and immobilized in a macroporous cryogel as a new antimicrobial agent. Bacillus subtilis ATCC 6633 was used as a safe and efficient bio-nano-factory during biosynthesis. The formation of CS/GO/ZnO was confirmed and characterized using different analyses including ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), selective area diffraction pattern (SADP), Zeta analyses, scanning electron microscope (SEM) and transmission electron microscopy (TEM). GO combined with ZnO NPs successfully and displayed an adsorption peak at 358 nm. The XRD results showed the crystalline composition of the loaded ZnO NPs on GO sheets. FTIR spectrum confirmed the presence of proteins during the synthesis which act as stabilizing and capping agents. The nanocomposite has a high negative surface charge (-32.8 ± 5.7 mV) which increases its stability. SEM and TEM showing the size of biosynthesized ZnO-NPs was in the range of 40-50 nm. The CS/GO/ZnO alone or immobilized in cryogel revealed good antimicrobial activities against B. cereus ATCC 14,579, Escherichia coli ATCC 25,922, and Candida albicans ATCC 10,231 in a dose-dependent manner. The CS/GO/ZnO cryogel revealed higher antimicrobial activity than GO/ZnO nanocomposite and standard antibiotics (amoxicillin and miconazole) with inhibition zones averages of 24.33 ± 0.12, 15.67 ± 0.03, and 17.5 ± 0.49 mm, respectively. The MIC values of the prepared nanocomposite against B. cereus, E. coli, and C. albicans were 80, 80, and 90 µg/ml compared to standard drugs (90, 120 and 150 µg/ml, respectively). According to the TEM ultrastructure studies of nanocomposite-treated microbes, treated cells had severe deformities and morphological alterations compared to the untreated cells including cell wall distortion, the separation between the cell wall and plasma membrane, vacuoles formation moreover complete cell lyses were also noted. In the cytotoxicity test of CS/GO/ZnO alone and its cryogel, there was a significant reduction (p˂0.05) in cell viability of WI-38 normal lung cell line after the concentration of 209 and 164 µg/ml, respectively. It showed the low toxic effect of the nanocomposite and its cryogel on the WI-38 line which implies its safety. In addition, water treatment with the CS/GO/ZnO cryogel decreased turbidity (0.58 NTU), total coliform (2 CFU/100 ml), fecal coliform (1 CFU/100 ml), fecal Streptococcus (2 CFU/100 ml), and heterotrophic plate counts (53 CFU/1 ml) not only in comparison with the chlorine-treated samples (1.69 NTU, 4 CFU/100 ml, 6 CFU/100 ml, 57 CFU/100 ml, and 140 CFU/1 ml, respectively) but also with the raw water samples (6.9 NTU, 10800 CFU/100 ml, 660 CFU/100 ml, 800 CFU/100 ml, and 4400 CFU/1 ml, respectively). Moreover, cryogel significantly decreased the concentration of different heavy metals, especially cobalt compared to chlorine (0.004 ppm, 0.002 ppm, and 0.001 ppm for raw water, chlorine-treated, and cryogel-treated groups, respectively) which helped in the reduction of their toxic effects.

CONCLUSION

This study provides an effective, promising, safe, and alternative nanocomposite to treat different human and animal pathogenic microbes that might be used in different environmental, industrial, and medical applications.