Zinc Oxide and Silver Nanoparticle Effects on Intestinal Bacteria

Fabrication and characterisation of human gut microbiome derived exopolysaccharide mediated silver nanoparticles - An in-vitro and in-vivo approach of Bio-Pm-AgNPs targeting Vibrio cholerae

Utilising bacteria to produce silver nanoparticles was highly favoured due to its ability to minimise costs and mitigate any potential negative environmental impact. Exopolysaccharides (EPS) extracted from the human gut microbe have demonstrated remarkable efficacy in combating various bacterial infections. Exopolysaccharide (EPS), a naturally occurring biomolecule found in the human gut isolate Proteus mirabilis DMTMMR-11, was characterised using analytical techniques such as Fourier transform infrared spectroscopy (FTIR), 1H-nuclear magnetic resonance, 13C-nuclear magnetic resonance (NMR), and chemical composition analysis, which confirms the presence of carbohydrates (81.03 ± 0.23), proteins (4.22 ± 1.2), uronic acid (12.1 ± 0.12), and nucleic acid content (2.44 ± 0.15) in exopolysaccharide. The one factor at a time (OFAT) and response surface methodology (RSM) - central composite design (CCD) approaches were used to optimise the production of Bio-Pm-AgNPs, leading to an increase in yield of up to 1.86 g/l. The Bio-Pm-AgNPs were then subjected to Fourier transform infrared spectroscopy (FTIR) which determines the functional groups, X-ray diffractometer confers that Bio-Pm-AgNPs are crystalline in nature, field emission-scanning electron microscopy (FE-SEM) reveals the morphology of Bio-Pm-AgNPs, energy dispersive X-ray spectroscopy (EDX) confirms the presence of elements like Ag, C and O, high-resolution transmission electron microscopy (HR-TEM) determines that the Bio-Pm-AgNPs are sphere-shaped at 75 nm. Dynamic light scattering (DLS) and zeta potential analysis were also carried out to reveal the physiological nature of Bio-Pm-AgNPs. Bio-Pm-AgNPs have a promising effect on the inhibitory mechanism of Vibrio cholerae cells at a MIC concentration of 20 μg/ml which significantly affects cellular respiration and energy metabolism through glycolysis and TCA cycles by deteriorating the enzyme responsible for ATP and NADH utilisation. The action of Bio-Pm-AgNPs reduces the purity and concentration of nucleic acids, which leads to higher DNA damage. In-vivo analysis reveals that the treatment of Bio-Pm-AgNPs decreased the colonisation of V. cholerae and improved the survival rates in C. elegans.

Characterization and genome analysis of Neobacillus mesonae NS-6, a ureolysis-driven strain inducing calcium carbonate precipitation

In this study, a highly promising bacterium was isolated from sandstone oil in the Ordos Basin, named strain NS-6 which exhibited exceptional urease production ability and demonstrated superior efficiency in inducing the deposition of calcium carbonate (CaCO3). Through morphological and physiochemical characteristics analysis, as well as 16S rRNA sequencing, strain NS-6 was identified as Neobacillus mesonae. The activity of urease and the formation of CaCO3 increased over time, reaching a maximum of 7.9 mmol/L/min and 184 mg (4.60 mg/mL) respectively at 32 h of incubation. Scanning Electron Microscopy (SEM) revealed CaCO3 crystals ranging in size from 5 to 6 μm, and Energy Dispersive X-ray (EDX) analysis verified the presence of calcium, carbon, and oxygen within the crystals. X-ray Diffraction (XRD) analysis further confirmed the composition of these CaCO3 crystals as calcite and vaterite. Furthermore, the maximum deposition of CaCO3 by strain NS-6 was achieved using response surface methodology (RSM), amounting to 193.8 mg (4.845 mg/mL) when the concentration of calcium ions was 0.5 mmol/L supplemented with 0.9 mmol/L of urea at pH 8.0. Genome-wide analysis revealed that strain NS-6 possesses a chromosome of 5,736,360 base pairs, containing 5,442 predicted genes, including 3,966 predicted functional genes and 1,476 functionally unknown genes. Genes like ureA, ureB, and ureC related to urea catabolism were identified by gene annotation, indicating that strain NS-6 is a typical urease-producing bacterium and possesses a serial of genes involved in metabolic pathways that mediated the deposition of CaCO3 at genetic level.

Antibacterial effectiveness of different zinc salts on Streptococcus mutans and Streptococcus sobrinus: An in-vitro study

Objectives

This in-vitro study aimed to evaluate the antibacterial effects of four zinc salts namely zinc chloride, zinc sulfate, zinc citrate and zinc acetate against Streptococcus mutans (S. mutans) and Streptococcus sobrinus (S. sobrinus).

Methods

Antibacterial susceptibility assay, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were undertaken to evaluate the inhibitory activities of different zinc salts against the tested bacteria. A scanning electron microscope (SEM) was used to evaluate the morphological changes of bacterial cells following exposure to zinc salts. Kruskal-Wallis and Mann-Whitney tests were used to compare the inhibitory effect of the different zinc salts.

Results

All zinc salts tested against S. mutans and S. sobrinus had a statistically and significantly smaller inhibition zone when compared to chlorhexidine, (P < 0.001). However, zinc chloride had the largest inhibition zone (20 mm ± 5.5) against S. sobrinus, which was comparable to chlorhexidine (22 mm ± 4) (P > 0.05). Zinc chloride, zinc sulfate and zinc acetate demonstrated higher MIC and MBC values against S. mutans compared to S. sobrinus. However, zinc citrate revealed the highest MIC and MBC values of 1 mg/mL and > 8 mg/mL for S. sobrinus and > 8 mg/mL for S. mutans, respectively.

Conclusion

Different zinc salts have displayed inhibitory growth effects against the common oral bacteria at very low concentrations except for zinc citrate which showed no inhibitory effect against these bacteria in vitro.

Nano-sized warriors: zinc chromium vanadate nanoparticles as a dual solution for eradicating waterborne enterobacteriaceae and fighting cancer

The revolution of biomedical applications has opened new avenues for nanotechnology. Zinc Chromium vanadate nanoparticles (VCrZnO4 NPs) have emerged as an up-and-coming candidate, with their exceptional physical and chemical properties setting them apart. In this study, a one-pot solvothermal method was employed to synthesize VCrZnO4 NPs, followed by a comprehensive structural and morphological analysis using a variety of techniques, including X-Ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Energy-dispersive X-ray, and X-ray photoelectron spectroscopy. These techniques confirmed the crystallinity of the NPs. The VCrZnO4 NPs were tested for their antibacterial activity against primary contaminants such as Enterobacteriaceae, including Shigella flexneri, Salmonella cholerasis, and Escherichia coli, commonly found in hospital settings, using the broth dilution technique. The results indicated a stronger antibacterial activity of VCrZnO4 NPs against Shigella and Salmonella than E. coli. Electron microscopy showed that the NPs caused severe damage to the bacterial cell wall and membrane, leading to cell death. In addition, the study evaluated the anticancer activities of the metal complexes in vitro using colorectal cancer cells (HCT-116) and cervical cancer cells (HELA), along with non-cancer cells and human embryonic kidney cells (HEK-293). A vanadium complex demonstrated efficient anticancer effects with half-inhibitory concentrations (IC₅₀) of 38.50+3.50 g/mL for HCT-116 cells and 42.25+4.15 g/mL for HELA cells. This study highlights the potential of Zinc Chromium vanadate nanoparticles as promising candidates for antibacterial and anticancer applications. Various advanced characterization techniques were used to analyze the properties of nanomaterials, which may help develop more effective and safer antibacterial and anticancer agents in the future.

Effect of Nanomaterials on Gut Microbiota

Nanomaterials are widely employed in everyday life, including food and engineering. Food additives on a nanoscale can enter the body via the digestive tract. The human gut microbiota is a dynamically balanced ecosystem composed of a multitude of microorganisms that play a crucial role in maintaining the proper physiological function of the digestive tract and the body's endocrine coordination. While the antibacterial capabilities of nanomaterials have received much interest in recent years, their impacts on gut microbiota ought to be cautioned about and explored. Nanomaterials exhibit good antibacterial capabilities in vitro. Animal studies have revealed that oral exposure to nanomaterials inhibits probiotic reproduction, stimulates the inflammatory response of the gut immune system, increases opportunistic infections, and changes the composition and structure of the gut microbiota. This article provides an overview of the impacts of nanomaterials, particularly titanium dioxide nanoparticles (TiO₂ NPs), on the gut microbiota. It advances nanomaterial safety research and offers a scientific foundation for the prevention, control, and treatment of illnesses associated with gut microbiota abnormalities.

Toxicity of transition metal nanoparticles: A review of different experimental models in the gastrointestinal tract

The development of nanotechnology is becoming a major trend nowadays. Nanoparticles (NPs) have been widely used in fields including food, biomedicine, and cosmetics, endowing NPs more opportunities to enter the human body. It is well-known that the gut microbiome plays a key role in human health, and the exposure of intestines to NPs is unavoidable. Accordingly, the toxicity of NPs has attracted more attention than before. This review mainly highlights recent advances in the evaluation of NPs' toxicity in the gastrointestinal system from the existing cell-based experimental models, such as the original mono-culture models, co-culture models, three-dimensional (3D) culture models, and the models established on microfluidic chips, to those in vivo experiments, such as mice models, Caenorhabditis elegans models, zebrafish models, human volunteers, as well as computer-simulated toxicity models. Owing to these models, especially those more biomimetic models, the outcome of the toxicity of NPs acting in the gastrointestinal tract can get results closer to what happened inside the real human microenvironment.

Nano-Based Drug Delivery Systems for Periodontal Tissue Regeneration

Periodontitis is a dysbiotic biofilm-induced and host-mediated inflammatory disease of tooth supporting tissues that leads to progressive destruction of periodontal ligament and alveolar bone, thereby resulting in gingival recession, deep periodontal pockets, tooth mobility and exfoliation, and aesthetically and functionally compromised dentition. Due to the improved biopharmaceutical and pharmacokinetic properties and targeted and controlled drug release, nano-based drug delivery systems have emerged as a promising strategy for the treatment of periodontal defects, allowing for increased efficacy and safety in controlling local inflammation, establishing a regenerative microenvironment, and regaining bone and attachments. This review provides an overview of nano-based drug delivery systems and illustrates their practical applications, future prospects, and limitations in the field of periodontal tissue regeneration.

Dunaliella salina Microalga Restores the Metabolic Equilibrium and Ameliorates the Hepatic Inflammatory Response Induced by Zinc Oxide Nanoparticles (ZnO-NPs) in Male Zebrafish

Microalgae are rich in bioactive compounds including pigments, proteins, lipids, polyunsaturated fatty acids, carbohydrates, and vitamins. Due to their non-toxic and nutritious characteristics, these are suggested as important food for many aquatic animals. Dunaliella salina is a well-known microalga that accumulates valuable amounts of carotenoids. We investigated whether it could restore the metabolic equilibrium and mitigate the hepatic inflammation induced by zinc oxide nanoparticles (ZnO-NPs) using male zebrafish which were exposed to 1/5^th 96 h-LC₅₀ for 4 weeks, followed by dietary supplementation with D. salina at two concentrations (15% and 30%) for 2 weeks. Collectively, ZnO-NPs affected fish appetite, whole body composition, hepatic glycogen and lipid contents, intestinal bacterial and Aeromonas counts, as well as hepatic tumor necrosis factor- α (TNF-α). In addition, the mRNA expression of genes related to gluconeogenesis (pck1, gys2, and g6pc3), lipogenesis (srepf1, acaca, fasn, and cd36), and inflammatory response (tnf-α, tnf-β, nf-kb2) were modulated. D. salina reduced the body burden of zinc residues, restored the fish appetite and normal liver architecture, and mitigated the toxic impacts of ZnO-NPs on whole-body composition, intestinal bacteria, energy metabolism, and hepatic inflammatory markers. Our results revealed that the administration of D. salina might be effective in neutralizing the hepatotoxic effects of ZnO-NPs in the zebrafish model.

Importance of Zinc Nanoparticles for the Intestinal Microbiome of Weaned Piglets

The scientific community is closely monitoring the replacement of antibiotics with doses of ZnO in weaned piglets. Since 2022, the use of zinc in medical doses has been banned in the European Union. Therefore, pig farmers are looking for other solutions. Some studies have suggested that zinc nanoparticles might replace ZnO for the prevention of diarrhea in weaning piglets. Like ZnO, zinc nanoparticles are effective against pathogenic microorganisms, e.g., Enterobacteriaceae family in vitro and in vivo. However, the effect on probiotic Lactobacillaceae appears to differ for ZnO and zinc nanoparticles. While ZnO increases their numbers, zinc nanoparticles act in the opposite way. These phenomena have been also confirmed by in vitro studies that reported a strong antimicrobial effect of zinc nanoparticles against Lactobacillales order. Contradictory evidence makes this topic still controversial, however. In addition, zinc nanoparticles vary in their morphology and properties based on the method of their synthesis. This makes it difficult to understand the effect of zinc nanoparticles on the intestinal microbiome. This review is aimed at clarifying many circumstances that may affect the action of nanoparticles on the weaning piglets' microbiome, including a comprehensive overview of the zinc nanoparticles in vitro effects on bacterial species occurring in the digestive tract of weaned piglets.

Gut Microbiota as a Mediator of Essential and Toxic Effects of Zinc in the Intestines and Other Tissues

The objective of the present study was to review the existing data on the association between Zn status and characteristics of gut microbiota in various organisms and the potential role of Zn-induced microbiota in modulating systemic effects. The existing data demonstrate a tight relationship between Zn metabolism and gut microbiota as demonstrated in Zn deficiency, supplementation, and toxicity studies. Generally, Zn was found to be a significant factor for gut bacteria biodiversity. The effects of physiological and nutritional Zn doses also result in improved gut wall integrity, thus contributing to reduced translocation of bacteria and gut microbiome metabolites into the systemic circulation. In contrast, Zn overexposure induced substantial alterations in gut microbiota. In parallel with intestinal effects, systemic effects of Zn-induced gut microbiota modulation may include systemic inflammation and acute pancreatitis, autism spectrum disorder and attention deficit hyperactivity disorder, as well as fetal alcohol syndrome and obesity. In view of both Zn and gut microbiota, as well as their interaction in the regulation of the physiological functions of the host organism, addressing these targets through the use of Zn-enriched probiotics may be considered an effective strategy for health management.