Preparation, characterization, antimicrobial and cytotoxicity studies of copper/zinc- loaded montmorillonite

Analytical and Antimicrobial Characterization of Zn-Modified Clays Embedding Thymol or Carvacrol

Carvacrol and thymol are broad-spectrum natural antimicrobial agents. To reduce their volatility and improve their antimicrobial performance, synergistic systems were prepared loading the active molecules in zinc-modified clays. Montmorillonite (MMT) and zeolite (ZEO) were modified with zinc ions (ZnMMT and ZnZEO), with well-known antimicrobial properties, and then with carvacrol or thymol, reaching the 26 ± 3% and 33 ± 2% w/w of loading, respectively. The resulting hybrid materials were characterized by FT-IR, XPS, XRD, TGA, and GC-MS to evaluate carvacrol/thymol release in simulating food matrices. Antimicrobial assays carried out using spoiler and pathogenic bacterial strains showed that the antimicrobial activity of both thymol and carvacrol was largely preserved once they were loaded into Zn-modified clays. However, MMT hybrids showed an antibacterial activity significantly higher than ZEO hybrids at 50 mg/mL of thymol and carvacrol. For this reason, deeper antimicrobial evaluations were carried out only for ZnMMT composites. ZnMMT loaded with thymol or carvacrol produced inhibition zones against most of the target strains, also at 3.12 mg/mL, while the positive controls represented by the single molecule thymol or carvacrol were not active. The hybrid materials can be useful for applications in which the antimicrobial activity of natural molecules need to be displayed over time as requested for the control of microbial pathogens and spoilage bacteria in different applications, such as active packaging, biomaterials, and medical devices.

Metakaolin-Based Geopolymers Filled with Industrial Wastes: Improvement of Physicochemical Properties through Sustainable Waste Recycling

The increasing global demand for cement significantly impacts greenhouse gas emissions and resource consumption, necessitating sustainable alternatives. This study investigates fresh geopolymer (GP) pastes incorporating 20 wt.% of five industrial wastes-suction dust, red mud from alumina production, electro-filter dust, and extraction sludges from food supplement production and from partially stabilized industrial waste-as potential replacements for traditional cement. Consistent synthesis methods are used to prepare the geopolymers, which are characterized for their physicochemical, mechanical, and biological properties. Ionic conductivity and pH measurements together with integrity tests, thermogravimetry analysis (TGA), and leaching analysis are used to confirm the stability of the synthesized geopolymers. Fourier-transform Infrared (FT-IR) spectroscopy is used to follow geopolymerization occurrences. Results for ionic conductivity, pH, and integrity revealed that the synthesized GPs were macroscopically stable. TGA revealed that the main mass losses were ascribable to water dehydration and to water entrapped in the geopolymer networks. Only the GP filled with the powder of the red mud coming from alumina production experienced a mass loss of 23% due to a partial waste degradation. FT-IR showed a red shift in the main Si-O-(Si or Al) absorption band, indicating successful geopolymer network formations. Additionally, most of the GPs filled with the wastes exhibited higher compressive strength (37.8-58.5 MPa) compared to the control (22 MPa). Only the GP filled with the partially stabilized industrial waste had a lower mechanical strength as its structure was highly porous because of gas formation during geopolymerization reactions. Despite the high compressive strength (58.5 MPa) of the GP filled with suction dust waste, the concentration of Sb leached was 25 ppm, which limits its use. Eventually, all samples also demonstrated effective antimicrobial activity against Escherichia coli and Staphylococcus aureus due to the alkaline environment and the presence of metal cations able to react with the bacterial membranes. The findings revealed the possibility of recycling these wastes within several application fields.

Effects of exposing Japanese quail eggs to a low dose of gamma radiation and in ovo feeding by two sources of trace elements on embryonic development activities

The present study investigated the influence of exposing quail eggs to low-dose gamma radiation (GR) and in ovo feeding with 2 sources of a mixture of trace elements (Zn, Fe, and Cu), including sulfate (TES) and loaded with montmorillonite (TEM), on embryonic development activities and prehatch quality. A total of 960 eggs on the seventh day of incubation were randomly divided into 6 groups (160 eggs/group) with 4 replicate of 40 eggs in each. A 3 × 2 factorial arrangement experiment was performed and included 3 sources in ovo feeding with a mixture of trace elements (Zn, Fe, and Cu), including 0 mg/egg, 50 mg TES/egg, and 50 mg TEM/egg with egg irradiation using 0 and 0.2 Gy from GR. Eggs injected with 50 mg TEM/egg and exposed to 0.2 Gy from GR (TEM/GR) was significantly (P ≤ 0.05 and 0.01) higher in hatchability, hatch body weight, and relative organ weight (liver, gizzard, proventriculus, heart, and intestine). The obtained results indicated significant (P ≤ 0.05) decreased in the serum concentration of malondialdehyde (MDA) in TEM/GR group. There was significant (P ≤ 0.05) increased of catalase (CAT) activity and the concentrations of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in TEM/GR group; however; total antioxidant capacity (T-AOC) was significant (P ≤ 0.05) increased in CT/GR group. Serum concentrations of immunoglobulin M (IgM) (P ≤ 0.05) and tumor necrosis factor-alpha (TNF-α) were increased in the TEM/CR group; the concentration of transforming growth factor beta (TGF-β) significant (P ≤ 0.05) increased in the TEM/GR group; and interleukins (IL6 and IL10) showed no significant differences among the groups. Our results showed increase in thyroxine and myostatin concentrations with TES/CR and CT/GR of our study groups, respectively. The relative mRNA expression levels of the GH, IGF-1, and Fas cell surface death receptor (FAS) genes were significantly (P ≤ 0.05 and 0.01) upregulated in the liver tissue of the TEM/GR group compared with the other groups. In conclusion, TEM/GR was the best treatment for improving prehatch quality, increasing serum antioxidant enzyme activities, and promoting the expression of growth and immune genes in fertilized quail eggs.

Synergistic Promotion System of Montmorillonite with Cu2+ and Benzalkonium Chloride for Efficient and Broad-Spectrum Antibacterial Activity

By intercalating montmorillonite (MMT) with Cu2+ and benzalkonium chloride (BAC), the present work constructed a synergistic promotion system (Cu2+/BAC/MMT). MMT not only enhances the thermal stability of Cu2+ and BAC but also facilitates the controlled release of Cu2+ and BAC. Concurrently, the introduction of BAC improves the material's organic compatibility. In vitro assays show that the "MIC+" of Cu2+/BAC/MMT against Staphylococcus aureus is merely 7.32 mg/L and 55.56 mg/L against Escherichia coli. At concentrations of 10 and 25 mg/L, Cu2+/BAC/MMT inactivates 100% of S. aureus and E. coli within 2 h, respectively. Furthermore, it is confirmed that the prepared Cu2+/BAC/MMT exhibits a long-term antibacterial ability through antibacterial experiments and release tests. Also, the biosafety of this material was also substantiated by in vitro cytotoxicity tests. These comprehensive findings indisputably portend that Cu2+/BAC/MMT holds promise to supplant antibiotics as an efficacious treatment modality for bacterial infections.

A Review on Montmorillonite-Based Nanoantimicrobials: State of the Art

One of the crucial challenges of our time is to effectively use metal and metal oxide nanoparticles (NPs) as an alternative way to combat drug-resistant infections. Metal and metal oxide NPs such as Ag, Ag₂O, Cu, Cu₂O, CuO, and ZnO have found their way against antimicrobial resistance. However, they also suffer from several limitations ranging from toxicity issues to resistance mechanisms by complex structures of bacterial communities, so-called biofilms. In this regard, scientists are urgently looking for convenient approaches to develop heterostructure synergistic nanocomposites which could overcome toxicity issues, enhance antimicrobial activity, improve thermal and mechanical stability, and increase shelf life. These nanocomposites provide a controlled release of bioactive substances into the surrounding medium, are cost effective, reproducible, and scalable for real life applications such as food additives, nanoantimicrobial coating in food technology, food preservation, optical limiters, the bio medical field, and wastewater treatment application. Naturally abundant and non-toxic Montmorillonite (MMT) is a novel support to accommodate NPs, due to its negative surface charge and control release of NPs and ions. At the time of this review, around 250 articles have been published focusing on the incorporation of Ag-, Cu-, and ZnO-based NPs into MMT support and thus furthering their introduction into polymer matrix composites dominantly used for antimicrobial application. Therefore, it is highly relevant to report a comprehensive review of Ag-, Cu-, and ZnO-modified MMT. This review provides a comprehensive overview of MMT-based nanoantimicrobials, particularly dealing with preparation methods, materials characterization, and mechanisms of action, antimicrobial activity on different bacterial strains, real life applications, and environmental and toxicity issues.

Zinc Oxide Nanoparticles Boost the Immune Responses in Oreochromis niloticus and Improve Disease Resistance to Aeromonas hydrophila Infection

Zinc is an essential element affecting immune responses in aquatic organisms. In the present research, the immunomodulating effect of zinc oxide nanoparticles (ZnO NPs) was studied in Nile tilapia (Oreochromis niloticus). The minimum inhibitory concentration of zinc oxide nanoparticles (ZnO NPs) for Aeromonas hydrophila was estimated at 60 µg/mL. To evaluate the efficacy of ZnO NPs for improving disease resistance against A. hydrophila, three hundred fish were divided into 5 groups. Fish in the group T1 maintained on the control feed, T2 and T3 feed on ZnO at 60 and 30 µg/g, while T4 and T5 received ZnO NPs at 60 and 30 µg/g, respectively for 8 weeks. Immune responses were evaluated by determining the phagocytic activity, serum antibacterial activity, lysozymes, respiratory burst activity, and also gene expression of immunoglobin M-2, tumor necrosis factor-α, interleukin (IL)-1β, heat shock proteins, IL-10, insulin growth factor 1, transforming growth factor-β2, superoxide dismutase enzyme, and catalase enzyme genes. Results indicated that groups that received ZnO NPs have exaggerated immune response and upregulation in the most of expressed immune-related genes. After the feeding trial, all groups were experimentally infected with A. hydrophila, and the mortality rate was monitored. Among all the treated groups, a higher survival rate and disease resistance were observed for fish that received ZnO NPs at 30 and 60 µg/g. The inclusion of ZnO NPs in O. niloticus feed improves both fish immune response and disease resistance against A. hydrophila.

Water-fueled autocatalytic bactericidal pathway based on e-Fenton-like reactions triggered by galvanic corrosion and extracellular electron transfer

Water is generally considered to be an undesirable substance in fuel system, which may lead to microbial contamination. The antibacterial strategies that can turn water into things of value with high disinfection efficacy have been urgently needed for fuel system. Here, we reveal a water-fueled autocatalytic bactericidal pathway comprised by bi-metal micro-electrode system, which can spontaneously produce reactive oxygen species (mainly H₂O₂ and O₂^•-) by the electron Fenton-like reaction in water medium without external energy., The respiratory chain component of bacteria and the galvanic corrosion on the coated metals were two electron sources in the system. The specific model of Ag-Ru water-fueled autocatalytic (WFA) microelectrode particles presents extremely high disinfection efficiency (>99.9999%) in less than one hour for three aerobic bacteria (Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis) in LB media and high disinfection efficiency for the anaerobic bacteria (Desulfovibrio alaskensis) in Postgate E media without natural light irradiation. Overall, the novel WFA Ag-Ru antibacterial material explored in this study has a high potential for sterilizing applications in fuel system and this work provides the potential for the development of non-chemical and water-based antibacterial materials, such as WFA Ag-Ru antibacterial coating on stainless steel.

Bioactive compounds, antibiotics and heavy metals: effects on the intestinal structure and microbiome of monogastric animals – a non-systematic review

The intestinal structure and gut microbiota are essential for the animals‘ health. Chemical components taken with food provide the right environment for a specific microbiome which, together with its metabolites and the products of digestion, create an environment, which in turn is affects the population size of specific bacteria. Disturbances in the composition of the gut microbiota can be a reason for the malformation of guts, which has a decisive impact on the animal‘ health. This review aimed to analyse scientific literature, published over the past 20 years, concerning the effect of nutritional factors on gut health, determined by the intestinal structure and microbiota of monogastric animals. Several topics have been investigated: bioactive compounds (probiotics, prebiotics, organic acids, and herbal active substances), antibiotics and heavy metals (essentaial minerals and toxic heavy metals).

Modified Montmorillonite Improved Growth Performance of Broilers by Modulating Intestinal Microbiota and Enhancing Intestinal Barriers, Anti-Inflammatory Response, and Antioxidative Capacity

This study aims to explore the effects of modified montmorillonite (MMT, copper loading) on the growth performance, gut microbiota, intestinal barrier, antioxidative capacity and immune function of broilers. Yellow-feathered broilers were randomly divided into control (CTR), modified montmorillonite (MMT), and antibiotic (ANTI) groups. Results revealed that MMT supplementation increased the BW and ADG and decreased the F/R during the 63-day experiment period. 16S rRNA sequencing showed that MMT modulated the cecal microbiota composition of broilers by increasing the relative abundance of two phyla (Firmicutes and Bacteroidetes) and two genera (Bacteroides and Faecalibacterium) and decreasing the abundance of genus Olsenella. MMT also improved the intestinal epithelial barrier indicated by the up-regulated mRNA expression of claudin-1, occludin, and ZO-1 and the increased length of microvilli in jejunum and the decreased levels of DAO and D-LA in serum. In addition, MMT enhanced the immune function indicated by the increased levels of immunoglobulins, the decreased levels of MPO and NO, the down-regulated mRNA expression of IL-1β, IL-6, and TNF-α, and the up-regulated mRNA expression of IL-4 and IL-10. Moreover, MMT down-regulated the expression of jejunal TLRs/MAPK/NF-κB signaling pathway-related genes (TLR2, TLR4, Myd88, TRAF6, NF-κB, and iNOS) and related proteins (TRAF6, p38, ERK, NF-κB, and iNOS). In addition, MMT increased the antioxidant enzyme activities and the expression of Nrf2/HO-1 signaling pathway-related genes and thereby decreased the apoptosis-related genes expression. Spearman’s correlation analysis revealed that Bacteroides, Faecalibacterium, and Olsenella were related to the inflammatory index (MPO and NO), oxidative stress (T-AOC, T-SOD, and CAT) and intestinal integrity (D-LA and DAO). Taken together, MMT supplementation improved the growth performance of broilers by modulating intestinal microbiota, enhancing the intestinal barrier function, and improving inflammatory response, which might be mediated by inhibiting the TLRs/MAPK/NF-κB signaling pathway, and antioxidative capacity mediated by the Nrf2/HO-1 signaling pathway.

Preventive effects of the Rehmannia glutinosa Libosch and Cornus officinalis Sieb herb couple on chronic kidney disease rats via modulating the intestinal microbiota and enhancing the intestinal barrier

CKD is a clinical syndrome with slow development and gradual deterioration of renal function. At present, modern medicine still lacks an ideal treatment method for this disease, while TCM has accumulated rich clinical experience in the treatment of CKD, which can effectively improve renal function and delay renal failure, and has unique advantages. RC is widely used in clinical practice to treat CKD, especially the “Kidney-Yin” deficiency syndrome. However, the compatibility mechanisms responsible for its effects in experimental studies, including preclinical and clinical research studies, are still not fully understood. Adenine-induced CKD rats were used to investigate the preventive effect of RC on CKD rats. Based on the high-throughput 16S rRNA gene sequencing results from Illumina, we discussed the intestinal flora abundance in rats in different treatment groups. According to a PCA and a PCoA based on a distance matrix, there was a clear separation of gut microbiome profiles between normal rats and model rats in terms of beta diversity. The abundance of Firmicutes in CKD rats was relatively increased, while that of Bacteroidetes was decreased. It is clear that the plot for the RC group was closer to that of the normal group, suggesting that the RC group had higher similarities among bacterial members with N rats. Ussing chamber, Western blot, and PCR assays were used to investigate the effects of RC on intestinal barrier function and its molecular mechanism in model animals. The results indicated that the protein expressions of ZO-1, claudin-1, and occludin-1 were decreased significantly in chronic kidney disease rats with the induction of adenine. With the treatment of RG, CO, and RC, the intestinal barrier was repaired due to the upregulated expressions of the aforementioned proteins in CKD rats. Based on our findings, RC appears to strengthen the intestinal barrier and modulate gut microbiota in adenine-induced CKD rats. This project revealed the compatibility mechanism of RC in regulating the intestinal microecology and barrier function to intervene in CKD and provided the basis and ideas for the clinical application of RC and the development of innovative drugs for CKD.

A super absorbent polymer containing copper to control Plenodomus tracheiphilus the causative agent of mal secco disease of lemon

The aim of this study was to determine the effectiveness of a Super absorbent polymer (SAP) containing copper (SAP-Cu) in controlling mal secco disease (MSD) of lemon caused by the fungus Plenodomus tracheiphilus. Super absorbent polymer containing copper was characterized by atomic absorption spectrometry (AAS) and UV-VIS spectroscopy. In vitro tests were performed to determine the inhibitory effects of SAP-Cu against the pathogen on both potato-dextrose-agar medium and naturally infected lemon cuttings. Super absorbent polymer was able to absorb up to about 200 and 30 times its weight of ionized water and copper (II) sulfate solution (Cu²⁺ ions at the concentration 236 mM), respectively. The distribution of copper released on twigs after 24 h of contact with SAP-Cu was determined by secondary ion mass spectrometry with time-of-flight analyzer (ToF-SIMS). Super absorbent polymer containing copper significantly inhibited the viability of P. tracheiphilus in lemon twigs. Overall, the results of this study showed that the SAP could be a suitable carrier of antifungal compounds.

Mechanical and antibacterial properties of ZnO/chitosan bio-composite films

In the current study, ZnO/chitosan bio-composite films were produced via solution-casting method. Two different ZnO powders, micrometer (d50 ≅ 1.5 μm) and nanometer sized (d50 ≅ 100 nm), were used to investigate the effect of ZnO particle size and concentration (0, 2, and 8% w/w of chitosan) on the mechanical and antibacterial properties of the ZnO/chitosan bio-composite films. The incorporation of the ZnO powders into the chitosan film resulted in an increase in the tensile strength (TS) and a decrease in the elongation at break (EB) values. Mechanical test results revealed that TS and EB properties were considerably affected (p < 0.05) by the concentration and particle size of the ZnO reinforcement. Disc diffusion method demonstrated good antibacterial activities of bio-composite films containing high amount of ZnO (8% w/w of chitosan) against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, and Bacillus subtilis. The growth-limiting effect of the films was more pronounced for S. aureus and K. pneumoniae. Due to enhanced TS and imparted antibacterial activity of the produced ZnO/chitosan bio-composite films, these materials are promising candidates for applications such as food packaging, wound dressing, and antibacterial coatings for various surfaces.

Chemical Profile, Antioxidant, Antimicrobial, and Anticancer Activities of the Water-Ethanol Extract of Pulicaria undulata Growing in the Oasis of Central Saudi Arabian Desert

Pulicaria undulata (L.) C. A. Mey has multiple uses as part of the traditional medicament, and several biological activities of the plant have been corroborated in the scientific literature. The current work evaluates the phytochemical constituents and biological properties of the water-ethanol extract of the P. undulata growing in Qassim, the central arid regions of the Kingdom of Saudi Arabia. Qualitative UPLC-ESIQ-TOF analysis identified 27 compounds belonging to the phenolics, flavonoids, triterpenes, coumarins, and of fatty acids chemical classes. The quantitative analysis exhibited 33.3 mg/g GAE (Gallic Acid Equivalents), and 10.8 mg/g QE (Quercetin Equivalents) of the phenolics and flavonoids in the plant’s concentrated (to dryness) water-ethanol extract. The trace elements analysis of the plant’s dry powder established the presence of copper (20.13 µg/kg), and zinc (68.2 µg/kg) in the higher levels of occurrences. In terms of the antioxidant potential of the plant’s extract, the ferric-reducing, and free-radicals scavenging activities were recorded at 47.11 mg/g, and 19.13 mg/g equivalents of the concentrated to dryness water-ethanol extract of the plant. The water-ethanol extract of P. undulata also exhibited antimicrobial activity against the tested Gram-positive bacteria, while no activity was observed against the tested Gram-negative bacteria, or the fungi. The MIC (minimum inhibitory concentration) values were in the range of 49 to 1563 µg/mL, whereas the MBC (minimum bactericidal concentration) values ranged from 49 to 3125 µg/mL, against the tested Gram-positive bacteria. The P. undulata water-ethanol extract also exhibited potent cytotoxic effects with the IC₅₀ value at 519.2 µg/mL against the MCF-7 breast cancer cell-lines, followed by the anticancer activity of erythroleukemic cell-lines, K562 at 1212 µg/mL, and pancreatic cell-lines, PANC-1, at 1535 µg/mL, as compared to the normal fibroblast cells (4048 µg/mL). The Annexin-V assay demonstrated that, as the P. undulata extract’s dose increased from IC₅₀ to twice of the IC₅₀, the percentage of the necrosis was found to be increased in the late apoptosis stage of the cancer cells. These data confirmed the P. undulata extract’s ability to inhibit several human cancer cell lines’ growth in comparison to other local halophytes. The antimicrobial activity of the plant was also confirmed.

Dietary copper/zinc-loaded montmorillonite improved growth performance and intestinal barrier and changed gut microbiota in weaned piglets

The effects of copper/zinc-loaded montmorillonite (Cu/Zn-Mt) on growth performance, intestinal barrier and gut microbiota of weaned pigs were investigated in the present study. A total of 108 piglets (Duroc × Landrace × Yorkshire; 6.36 kg; weaned at 21 ± 1 d age) were used in this experiment. The pigs were randomly assigned to three treatments with six replicates, six pigs in each replicate. The three treatments were as follows: (1) control group: basal diet; (2) Cu/Zn-Mt group: basal diet supplemented with 39 mg/kg Cu and 75 mg/kg Zn as Cu/Zn-Mt; and (3) Cu +Zn +Mt group: basal diet supplemented with the mixture of copper sulphate, zinc sulphate and montmorillonite (equivalent to the copper and zinc in the Cu/Zn-Mt treatment). The results indicated that, compared with the pigs from control group, average daily gain and gain: feed ratio were increased and the faecal score on days 7 and 14 after weaning was decreased by supplementation of Cu/Zn-Mt; intestinal transepithelial electrical resistance (TER) and expressions of tight junction protein claudin-1 and zonula occludens-1 were increased, and intestinal permeability of fluorescein isothiocyanate-dextran 4 kDa was decreased by supplementation with Cu/Zn-Mt. According to the Illumina-based sequencing results, Cu/Zn-Mt supplementation increased the relative abundance of core bacteria (Lactococcus, Bacillus) at genus level and decreased the potentially pathogenic bacteria (Streptococcus and Pseudomonas) in colon of weaned piglets. However, the piglets fed with the mixture of copper sulphate, zinc sulphate and montmorillonite showed no effects in above parameters in comparison with the pigs from control group. In conclusion, dietary Cu/Zn-Mt could improve growth performance, decrease the diarrhoea and improve intestinal barrier and bacterial communities of weaned pigs. The results indicated that 'loading' of montmorillonite with Zn and Cu changed not only its chemical but also its nutritional properties.

Preparation, characterization and antibacterial mechanism of the chitosan coatings modified by Ag/ZnO microspheres

BACKGROUND

To improve the physicochemical and antibacterial properties of coatings, the chitosan (CS) coatings were respectively prepared by a casting method with zinc oxide (ZnO) and silver (Ag)/ZnO microspheres as modifiers. The chemical structures and micromorphology of ZnO, Ag/ZnO microspheres and CS coatings were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. Furthermore, using the dominant spoilage bacteria of aquatic products, Shewanella putrefaciens and Pseudomonas aeruginosa, as objects, the antibacterial activities and mechanism of the CS coatings were investigated.

RESULTS

The results show that ZnO and Ag/ZnO microspheres are dispersed homogeneously in the CS coatings. After modified by ZnO and Ag/ZnO microspheres, the mechanical properties and antibacterial abilities of the CS coatings are improved, and that of 0.5% Ag/ZnO-CS coating is the optimal. For pure CS coating, the bacterial cell membrane is damaged slightly because of the electrostatic interaction between NH³⁺ of CS and the negative charge on bacterial surface. After treated by ZnO-CS composite coating, the bacterial cell membrane is destroyed badly on account of the earlier-mentioned ion interaction and disturbing the synthesis of high molecular weight total protein.

CONCLUSION

With regard to Ag/ZnO-CS composite coating, the bacterial cell membrane is damaged seriously and cell contents are completely released due to ion interaction, disturbing the synthesis of high molecular weight total protein and low molecular weight membrane protein. Hence, Ag/ZnO-CS composite coatings are antimicrobial materials and food preservative materials with great potential application. © 2020 Society of Chemical Industry.

Bacteriostatic and bactericidal clays: an overview

This article aims to draw an overview on the actual knowledge on bacteriostatic and bactericidal natural clays. Particular emphasis is given to the role of clay itself, the action of reduced metals located either in the structure of clay minerals or external to them as constituents of associate minerals, and the definition of the mechanisms of action based on the achievements found in all available studies being carried out so far. The term bactericidal is herein used when a clay or a clay mineral kill the bacteria, whereas the term bacteriostatic is used when those minerals stop bacteria growth and replication. The second part of this article deals with experimental studies on bactericidal natural clay, experience and perspective for the preparation of bactericidal natural clays, interesting on the authors perspective and experience for the preparation of pathogens safe both therapeutic and cosmetic natural mud/natural peloid, and better yet of both therapeutic 87oooand cosmetic peloid itself and designed and engineered peloid. The authors also show how to convert non-antimicrobial clay into antimicrobial one, opening the way in the field of pelotherapy to the preparation of sanitary safe peloids addressed, for instance, to the treatment of rheumatic disabilities, as well as to the preparation of antimicrobial peloids and, in particular, of dermatological ointments, all able to fight infectious skin disorders.

Adsorption of deoxynivalenol by pillared montmorillonite

Deoxynivalenol (DON) is found widely in foods and feeds that are contaminated with mildew and is one of the most harmful mycotoxins, threating not only human health but also impacting animal husbandry. Various physical, chemical and biological detoxification strategies have been applied in the past to reduce mycotoxin contamination. As a practical and economic method, addition of montmorillonite (Mt) offers the potential to eliminate mycotoxins, especially aflatoxin B1 (AFB₁) and zearalenone (ZEA). Our study aimed to control DON, for the first time, using environmentally friendly Mt, modified with aluminum, iron and titanium via a pillaring effect to enlarge interlayer spacing. The materials were characterized using XRD, FTIR, SEM, EDS and BET. Spacing of the pillared Mt layers was shown to exceed that of raw Mt and could be tuned using the pillaring reagents (Al, Fe and Ti, 0.01 to 2.00 eq. relative to the cation exchange capacity of Mt). Adsorption of DON by pillared Mt was investigated using UPLC-MSMS (at pH 2.0 and 6.8). The results demonstrated that the adsorption ratios of 1.00-Al-Mt, 0.50-Fe-Mt and 1.00-Ti-Mt were 23.6%, 14.7% and 23.4%, respectively at pH 2.0 and 27.1%, 21.8%, and 27.4% correspondingly at pH 6.8 when added at 1.0 mg, which is 3-4 times higher than raw Mt (6.3-6.8% at pH 2.0 and 7.3-8.1% at pH 6.8). It was also found that with increased addition of pillared Mt (2.5 mg), the adsorption ratio approached 35%. The time for reaching equilibrium was approximately 120 min. These results demonstrated that Mt after pillaring modifications with Al, Fe and Ti can have potential for the control of DON in foods and feeds.

Bimetallic Nanoparticles for Antimicrobial Applications

Highly effective antimicrobial agents are needed to control the emergence of new bacterial strains, their increased proliferation capability, and antibacterial resistance that severely impact public health, and several industries including water, food, textiles, and oil and gas. Recently, bimetallic nanoparticles, formed via integration of two different metals, have appeared particularly promising with antibacterial efficiencies surpassing that of monometallic counterparts due to synergistic effects, broad range of physiochemical properties, and diverse mechanisms of action. This work aims to provide a review on developed bimetallic and supported bimetallic systems emphasizing in particular on the relation between synthesis routes, properties, and resulting efficiency. Bimetallic nanostructures on graphene, zeolites, clays, fibers, polymers, as well as non-supported bimetallic nanoparticles are reviewed, their synthesis methods and resulting properties are illustrated, along with their antimicrobial activity and potential against different strains of microbes.

High-Potential surface on zirconia ceramics for bacteriostasis and biocompatibility

Bacteria easily adhere, colonize, and form biofilm on oral implants subsequently causing periimplantation periarthritis and mechanical loosening. Previous studies show that a high potential surface on polymeric implants can achieve surface bacteriostasis without side effects. In this study, a high surface potential is introduced to zirconia ceramics to mitigate bacterial infection. Carbon and nitrogen plasma immersion ion implantation (C-PIII and N-PIII) are conducted on zirconia ceramic samples sequentially to elevate the surface potential. The surface with a high potential but without ion leaching exhibits excellent antibacterial effects against oral bacteria and little bacterial resistance is triggered. The surface also has high strength and excellent biocompatibility. The nitrogen-containing inorganic structure with high potential can actualize bacteriostasis and biocompatibility on zirconia ceramics simultaneously and this new strategy can enhance the antibacterial ability of oral implants.

Zinc and Copper with New Triazine Hydrazone Ligand: Two Novel Organic Complexes Enhanced Expression of Peptide Growth Factors and Cytokine Genes in Weaned V-Line Rabbit

Simple Summary

Zinc and Copper are two important trace minerals, which are involved in numerous vital biological activities in animal’s body, such as enzyme activation and enhancement of immune function, growth, reproduction, DNA synthesis, cell division, and neurotransmitters production. Recently, the application of trace mineral organic complexes in animal feed received much more attention than the inorganic sources. The organic sources can contribute significantly to improving animals’ health and reproduction, as the minerals are more biologically available and absorbable than they are when coming from the inorganic sources. In this study, three injectable varieties of Zn and Cu supplementation, sulfate, inorganic (loaded with montmorillonite), and novel organic (ligand with triazine hydrazone), were tested with weaned rabbits. The results revealed that these three mineral types vary at the most biological responses, and only one category of our novel organic complexes provided consistent animal performance improvement, including weight gain, serum antioxidant, meat quality, intestine morphometry, and the expression of peptide growth factors and cytokine genes. To our knowledge, this is the first work on the Zn and Cu with triazine hydrazone ligand as two organic complexes in rabbits.

Abstract

Two novel transitional organic Zn/Cu complexes based on a new biocompatible bidentate triazine–hydrazone ligand (Thz) was designed, synthesized, and evaluated in this study. This study evaluated the effects of injecting 60 mg of Zn and 40 mg of Cu in three different forms, twice per week, for eight weeks on growth performance, expression of growth factors and cytokine genes, carcass yield, blood biochemicals, and intestinal morphology in weaned rabbits. The tested complexes were sulfate (Cu/ZnSO₄), montmorillonite (Cu/Zn-Mnt), and triazine hydrazone (Cu/Zn-Thz). A total of 60 V-line weaned rabbits at four weeks of age were assigned to four treatments (n = 15), which were intramuscularly injected with 0.5 mL of either (1) saline (control) or saline containing (2) Cu/ZnSO₄, (3) Cu/Zn-Mnt, or (4) Cu/Zn-Thz. Compared to the controls, the rabbits injected with Cu/Zn-Thz showed a higher (p < 0.01) growth rate, carcass yield (p < 0.05), and liver expression of insulin like growth factor-1 (IGF-1), growth hormone receptor (GHR), fibroblast growth factor-1 (FGF1), and transforming growth factor beta-1 (TGFB1) (p < 0.05), as well as better jejunum morphometric variables (p < 0.05). On the other hand, mRNA of FGF1, TGF1, TCIRG1, and adenosine deaminase (ADA) were higher expressed (p < 0.05) in the spleen tissues of Cu/Zn-Mnt group. Collectively, the results indicated that our novel synthesized organic complexes of Zn/Cu-Thz proved to be a suitable feed supplement, as it increased rabbit productive performance through enhancing expression of peptide growth factors and cytokine genes.

Harnessing Metal Homeostasis Offers Novel and Promising Targets Against Candida albicans

Fungal infections, particularly of Candida species, which are the commensal organisms of human, are one of the major debilitating diseases in immunocompromised patients. The limited number of antifungal drugs available to treat Candida infections, with the concomitant increasing incidence of multidrug-resistant (MDR) strains, further worsens the therapeutic options. Thus, there is an urgent need for the better understanding of MDR mechanisms, and their reversal, by employing new strategies to increase the efficacy and safety profiles of currently used therapies against the most prevalent human fungal pathogen, Candida albicans. Micronutrient availability during C. albicans infection is regarded as a critical factor that influences the progression and magnitude of the disease. Intracellular pathogens colonize a variety of anatomical locations that are likely to be scarce in micronutrients, as a defense strategy adopted by the host, known as nutritional immunity. Indispensable critical micronutrients are required both by the host and by C. albicans, especially as a cofactor in important metabolic functions. Since these micronutrients are not freely available, C. albicans need to exploit host reservoirs to adapt within the host for survival. The ability of pathogenic organisms, including C. albicans, to sense and adapt to limited micronutrients in the hostile environment is essential for survival and confers the basis of its success as a pathogen. This review describes that micronutrients availability to C. albicans is a key attribute that may be exploited when one considers designing strategies aimed at disrupting MDR in this pathogenic fungi. Here, we discuss recent advances that have been made in our understanding of fungal micronutrient acquisition and explore the probable pathways that may be utilized as targets.

Zinc phosphate-based nanoparticles as a novel antibacterial agent: in vivo study on rats after dietary exposure

Background

Development of new nanomaterials that inhibit or kill bacteria is an important and timely research topic. For example, financial losses due to infectious diseases, such as diarrhea, are a major concern in livestock productions around the world. Antimicrobial nanoparticles (NPs) represent a promising alternative to antibiotics and may lower antibiotic use and consequently spread of antibiotic resistance traits among bacteria, including pathogens.

Results

Four formulations of zinc nanoparticles (ZnA, ZnB, ZnC, and ZnD) based on phosphates with spherical (ZnA, ZnB) or irregular (ZnC, ZnD) morphology were prepared. The highest in vitro inhibitory effect of our NPs was observed against Staphylococcus aureus (inhibitory concentration values, IC₅₀, ranged from 0.5 to 1.6 mmol/L), followed by Escherichia coli (IC₅₀ 0.8-1.5 mmol/L). In contrast, methicillin resistant S. aureus (IC₅₀ 1.2-4.7 mmol/L) was least affected and this was similar to inhibitory patterns of commercial ZnO-based NPs and ZnO. After the successful in vitro testing, the in vivo study with rats based on dietary supplementation with zinc NPs was conducted. Four groups of rats were treated by 2,000 mg Zn/kg diet of ZnA, ZnB, ZnC, and ZnD, for comparison two groups were supplemented by 2,000 mg Zn/kg diet of ZnO-N and ZnO, and one group (control) was fed only by basal diet. The significantly higher (P < 0.05) Zn level in liver and kidney of all treated groups was found, nevertheless Zn NPs did not greatly influence antioxidant status of rats. However, the total aerobic and coliform bacterial population in rat feces significantly decreased (P < 0.05) in all zinc groups after 30 d of the treatment. Furthermore, when compared to the ZnO group, ZnA and ZnC nanoparticles reduced coliforms significantly more (P < 0.05).

Conclusions

Our results demonstrate that phosphate-based zinc nanoparticles have the potential to act as antibiotic agents.

Photo-controlled release of metal ions using triazoline-containing amphiphilic copolymers

Photo-controlled release of metal ions can be achieved by denitrogenation of triazoline from the micelles of amphiphilic copolymer, and has potential applications for biomedicines.

Influences of Copper/Zinc-Loaded Montmorillonite on Growth Performance, Mineral Retention, Intestinal Morphology, Mucosa Antioxidant Capacity, and Cytokine Contents in Weaned Piglets

The effects of copper/zinc-loaded montmorillonite (Cu/Zn-Mt) on growth performance, mineral retention, intestinal morphology, mucosa antioxidant capacity, and cytokine contents in weaned piglets were investigated in the present study. One hundred eight piglets weaned at 21 ± 1 days of age (Duroc × Landrace× Yorkshire; average initial weight of 6.36 kg) were allotted to three treatments for 2 weeks. The three treatments were as follows: (1) control group: basal diet; (2) Cu/Zn-Mt group: basal diet + 39 mg/kg Cu and 75 mg/kg Zn as Cu/Zn-Mt; (3) Cu + Zn + Mt group: basal diet + mixture of CuSO₄, ZnSO₄, and Mt (equal amount of Cu, Zn, and Mt to the Cu/Zn-Mt group). Each treatment had six pens of six piglets. The results showed that as compared with the control group and the Cu + Zn + Mt group, Cu/Zn-Mt supplementation increased (P < 0.05) the average daily gain and the gain/feed ratio; Cu/Zn-Mt supplementation increased (P < 0.05) the Cu and Zn concentrations in serum, jejunum, and ileum mucosa, villus height, the ratio of villus height to crypt depth, and the activities of SOD, GSH-Px, and IL-10 levels, and decreased the malondialdehyde concentrations in the jejunum and ileum, and intestinal IL-1β, IL-6, and TNF-α levels. Moreover, supplementation with the mixture of CuSO₄, ZnSO₄, and Mt had no effect on the growth performance, but increased the mucosa Cu and Zn concentrations, intestinal morphology, antioxidant capacity, and immune function in the duodenum, while it had no effect on the above indexes in the jejunum and ileum. The results indicated that Mt could be used as a controlled carrier for Cu and Zn, which made Cu/Zn-Mt have better biological activities in the intestine than the mixture of Cu, Zn, and Mt.

Preparation and in vitro evaluation of polycaprolactone/PEG/bioactive glass nanopowders nanocomposite membranes for GTR/GBR applications

In the present study, nanocomposite membranes are investigated using poly-ε-caprolactone (PCL), polyethylene glycol (PEG) and bioactive glass nanopowders (BGs) synthesized via solvent casting method with different reinforcement rates of BGs consisting of 3, 5 and 7 wt% for regenerating the periodontal tissue in vitro. These prepared membranes were evaluated by a vast range of essential tests; including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Transmition-electron microscopy (TEM), tensile testing before and after soaking in PBS solution, degradation and contact angle assessments as well as cell culture assays. In spite of the fact that the percentage of Cu incorporated into BGs was trivial, this negligible amount exerted major cytotoxic impact upon cells during in vitro cell tests. According to the results, the blended-membrane contained 7 wt% copper-free BGs indicated optimum characteristics including satisfactory mechanical and biodegradation features, more wettable surface, higher proliferation rates of adipose-derived stem cells (ADSCs), superior ALP activity and brilliant bone mineralization capacity which was confirmed by Alizarin red assay. As a consequence, it can be used as a desirable candidate for guided tissue/bone regeneration (GTR/GBR) to accelerate bone tissue healing.

Copper/zinc-loaded montmorillonite influences intestinal integrity, the expression of genes associated with inflammation, TLR4-MyD88 and TGF-β1 signaling pathways in weaned pigs after LPS challenge

This study was aimed at investigating whether dietary copper/zinc-loaded montmorillonite (Cu/Zn-Mt) could alleviate Escherichia coli LPS-induced intestinal injury through pro- and anti-inflammatory signaling pathways (TLRs, NLRs and TGF-β1) in weaned piglets. Eighteen 21-d-old pigs were randomly divided into three groups (control, LPS and LPS + Cu/Zn-Mt). After 21 d of feeding, pigs in the LPS group and LPS + Cu/Zn-Mt group received i.p. administration of LPS, whereas pigs in the control group received saline. At 4 h post-injection, jejunum samples were collected for analysis. The results indicated that, compared with the LPS group, supplemental Cu/Zn-Mt increased transepithelial electrical resistance, the expressions of anti-inflammatory cytokines (TGF-β1) in mRNA and protein levels, and decreased FD4 and the mRNA expression of pro-inflammatory cytokines (TNF-α, IL-6, IL-8 and IL-1β). The pro-inflammatory signaling pathways results demonstrated that Cu/Zn-Mt supplementation decreased the mRNA levels of TLR4 and its downstream signals (MyD88, IRAK1, TRAF6) but had no effect on NOD1 and NOD2 signals. Cu/Zn-Mt supplementation did not affect NF-κB p65 mRNA abundance, but down-regulated its protein expression. The anti-inflammatory signaling pathways results showed supplemental Cu/Zn-Mt also increased TβRII, Smad4 and Smad7 mRNA expressions. These findings suggested dietary Cu/Zn-Mt attenuated LPS-induced intestinal injury by alleviating intestinal inflammation, influencing TLR4-MyD88 and TGF-β1 signaling pathways in weaned pig.