Biogenic Synthesis of Novel Functionalized Selenium Nanoparticles by Lactobacillus casei ATCC 393 and Its Protective Effects on Intestinal Barrier Dysfunction Caused by Enterotoxigenic Escherichia coli K88

Synergistic interaction of nanoparticles and probiotic delivery: A review

Nanotechnology is an expanding and new technology that prompts production with nanoparticle-based (1-100 nm) organic and inorganic materials. Such a tool has an imperative function in different sectors like bioengineering, pharmaceuticals, electronics, energy, nuclear energy, and fuel, and its applications are helpful for human, animal, plant, and environmental health. In exacting, the nanoparticles are synthesized by top-down and bottom-up approaches through different techniques such as chemical, physical, and biological progress. The characterization is vital and the confirmation of nanoparticle traits is done by various instrumentation analyses like UV-Vis spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy, scanning electron microscope, transmission electron microscopy, X-ray diffraction, atomic force microscopy, annular dark-field imaging, and intracranial pressure. In addition, probiotics are friendly microbes which while administered in sufficient quantity confer health advantages to the host. Characterization investigation is much more significant to the identification of good probiotics. Similarly, haemolytic activity, acid and bile salt tolerance, autoaggregation, antimicrobial compound production, inhibition of pathogens, enhance the immune system, and more health-beneficial effects on the host. The synergistic effects of nanoparticles and probiotics combined delivery applications are still limited to food, feed, and biomedical applications. However, the mechanisms by which they interact with the immune system and gut microbiota in humans and animals are largely unclear. This review discusses current research advancements to fulfil research gaps and promote the successful improvement of human and animal health.

Anti-breast cancer activity of biosynthesized selenium nanoparticles using Bacillus coagulans supernatant

BACKGROUND

In the present study, Selenium Nanoparticles (SeNPs) were prepared using Bacillus coagulans, which is a type of Lactic Acid Bacteria (LAB), and then they were applied to treat breast cancer cells.

METHODS

The chemicophysical properties of the bioengineered SeNPs were investigated by Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM), zeta potential, dynamic light scattering, Fourier Transform Infrared Spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction analysis (XRD). The cytotoxic potential of SeNPs was evaluated by MTT assay against MCF-7 breast cancer cell line. The expression levels of apoptotic genes including BAX, BCL2, VEGF, ERBB2, CASP3, CASP9, CCNE1, CCND1, MMP2 and MMP9 were determined by real-time PCR. The rate of apoptosis and necrosis of the cancer cells as well as the results of the cell cycle were evaluated by flow cytometry method.

RESULTS

The synthesized SeNPs had an average particle size of about 24-40 nm and a zeta potential of -16.1 mV, indicating the high stability of SeNPs. EDX results showed presence of SeNPs because amount of selenium in SeNPs was 86.6 % by weight. The cytotoxicity results showed a concentration-dependent effect against MCF-7 cells. The half-maximal inhibitory concentration (IC50) values of B. coagulans supernatant and SeNPs against breast cancer cells were 389.7 µg/mL and 17.56 µg/mL, respectively. In addition, SeNPs synthesized by the green process exhibited enhanced apoptotic potential in MCF-7 cancer cells compared with bacterial supernatants. Cancer cells treated with IC50 concentration of SeNPs induced 32 % apoptosis compared to untreated cells (3 % apoptosis). The gene expression levels of BAX, CASP3, and CASP9 were upregulated, while the expression levels of BCL2, CCNE1, CCND1, MMP2, MMP9, VEGF, and ERBB2 were downregulated after SeNPs treatment of cells. The potential of SeNPs to induce cell apoptosis was demonstrated by the increase in the expression level of BAX gene and the decrease in the expression level of BCL2 after treatment of cancer cells with SeNPs.

CONCLUSION

The obtained results indicated that SeNPs had strong potential to induce significant cell apoptosis and are cytotoxic against the MCF-7 cancer cell line.

Enhanced Induction of Apoptosis and Cell Cycle Arrest in MCF-7 Breast Cancer and HT-29 Colon Cancer Cell Lines via Low-Dose Biosynthesis of Selenium Nanoparticles Utilizing Lactobacillus casei

As a leading global cause of mortality, cancer continues to pose a significant challenge. The shortcomings of prevalent cancer treatments, such as surgery, radiation therapy, and chemotherapy, necessitate the exploration of alternative therapeutic strategies. Selenium nanoparticles (SeNPs) have emerged as a promising solution, with their synthesis being widely researched due to their potential applications. Among the diverse synthesis methods for SeNPs, the green chemistry approach holds a distinctive position within nanotechnology. This research delves into the anti-proliferative and anticancer properties of green-synthesized SeNPs via the cell-free supernatant (CFS) of Lactobacillus casei (LC-SeNPs), with a specific focus on MCF-7 and HT-29 cancer cell lines. SeNPs were synthesized employing the supernatant of L. casei. The characterization of these green-synthesized SeNPs was performed using TEM, FE-SEM, XRD, FT-IR, UV-vis, energy-dispersive X-ray spectroscopy, and DLS. The biological impact of LC-SNPs on MCF-7 and HT-29 cancer cells was examined via MTT, flow cytometry, scratch tests, and qRT-PCR. Both FE-SEM and TEM images substantiated the spherical shape of the synthesized nanoparticles. The biosynthesized LC-SNPs reduced the survival of MCF-7 (by 20%) and HT-29 (by 30%) cells at a concentration of 100 μg/mL. Flow cytometry revealed that LC-SNPs were capable of inducing 28% and 23% apoptosis in MCF-7 and HT-29 cells, respectively. In addition, it was found that LC-SNPs treated MCF-7 and HT-29 cells were arrested in the sub-G1 phase. Gene expression analysis indicated that the expression levels of the CASP3, CASP9, and BAX genes were elevated after treating MCF-7 and HT-29 cells with LC-SNPs. Further, SeNPs were observed to inhibit migration and invasion of MCF-7 and HT-29 cancer cells. The SeNPs, produced via L. casei, demonstrated strong anticancer effects on MCF-7 and HT-29 cells, suggesting their potential as biological agents in cancer treatment following additional in vivo experiments.

Stress mechanism involved in the progression of alcoholic liver disease and the therapeutic efficacy of nanoparticles

Alcoholic liver disease (ALD) poses a significant threat to human health, with excessive alcohol intake disrupting the immunotolerant environment of the liver and initiating a cascade of pathological events. This progressive disease unfolds through fat deposition, proinflammatory cytokine upregulation, activation of hepatic stellate cells, and eventual development of end-stage liver disease, known as hepatocellular carcinoma (HCC). ALD is intricately intertwined with stress mechanisms such as oxidative stress mediated by reactive oxygen species, endoplasmic reticulum stress, and alcohol-induced gut dysbiosis, culminating in increased inflammation. While the initial stages of ALD can be reversible with diligent care and abstinence, further progression necessitates alternative treatment approaches. Herbal medicines have shown promise, albeit limited by their poor water solubility and subsequent lack of extensive exploration. Consequently, researchers have embarked on a quest to overcome these challenges by delving into the potential of nanoparticle-mediated therapy. Nanoparticle-based treatments are being explored for liver diseases that share similar mechanisms with alcoholic liver disease. It underscores the potential of these innovative approaches to counteract the complex pathogenesis of ALD, providing new avenues for therapeutic intervention. Nevertheless, further investigations are imperative to fully unravel the therapeutic potential and unlock the promise of nanoparticle-mediated therapy specifically tailored for ALD treatment.

Stress mechanism involved in the progression of alcoholic liver disease and the therapeutic efficacy of nanoparticles

Alcoholic liver disease (ALD) poses a significant threat to human health, with excessive alcohol intake disrupting the immunotolerant environment of the liver and initiating a cascade of pathological events. This progressive disease unfolds through fat deposition, proinflammatory cytokine upregulation, activation of hepatic stellate cells, and eventual development of end-stage liver disease, known as hepatocellular carcinoma (HCC). ALD is intricately intertwined with stress mechanisms such as oxidative stress mediated by reactive oxygen species, endoplasmic reticulum stress, and alcohol-induced gut dysbiosis, culminating in increased inflammation. While the initial stages of ALD can be reversible with diligent care and abstinence, further progression necessitates alternative treatment approaches. Herbal medicines have shown promise, albeit limited by their poor water solubility and subsequent lack of extensive exploration. Consequently, researchers have embarked on a quest to overcome these challenges by delving into the potential of nanoparticle-mediated therapy. Nanoparticle-based treatments are being explored for liver diseases that share similar mechanisms with alcoholic liver disease. It underscores the potential of these innovative approaches to counteract the complex pathogenesis of ALD, providing new avenues for therapeutic intervention. Nevertheless, further investigations are imperative to fully unravel the therapeutic potential and unlock the promise of nanoparticle-mediated therapy specifically tailored for ALD treatment.

Selenium-Fortified Kombucha-Pollen Beverage by In Situ Biosynthesized Selenium Nanoparticles with High Biocompatibility and Antioxidant Activity

Biogenic selenium nanoparticles (SeNPs) have been shown to exhibit increased bioavailability. Fermentation of pollen by a symbiotic culture of bacteria and yeasts (SCOBY/Kombucha) leads to the release of pollen content and enhances the prebiotic and probiotic effects of Kombucha. The aim of this study was to fortify Kombucha beverage with SeNPs formed in situ by Kombucha fermentation with pollen. Response Surface Methodology (RSM) was used to optimize the biosynthesis of SeNPs and the pollen-fermented Kombucha beverage. SeNPs were characterized by Transmission electron microscopy energy-dispersive X-ray spectroscopy (TEM-EDX), Fourier-transform infrared spectroscopy (FTIR), Dynamic light scattering (DLS), and Zeta potential. The pollen-fermented Kombucha beverage enriched with SeNPs was characterized by measuring the total phenolic content, antioxidant activity, soluble silicon, saccharides, lactic acid, and the total content of Se0. The polyphenols were identified by liquid chromatography-mass spectrometry (LC-MS). The pollen and the bacterial (nano)cellulose were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), FTIR, and X-Ray diffraction (XRD). We also assessed the in vitro biocompatibility in terms of gingival fibroblast viability and proliferation, as well as the antioxidant activity of SeNPs and the pollen-fermented Kombucha beverage enriched with SeNPs. The results highlight their increased biological performance in this regard.

Characterization and anti-inflammatory effect of selenium-enriched probiotic Bacillus amyloliquefaciens C-1, a potential postbiotics

A patented strain of Bacillus amyloliquefaciens C-1 in our laboratory could produce functional sodium selenite (Na2SeO3) under optimized fermentation conditions. With the strong stress resistance and abundant secondary metabolites, C-1 showed potential to be developed as selenium-enriched postbiotics. C-1 has the ability to synthesize SeNPs when incubated with 100 μg/ml Na2SeO3 for 30 h at 30 °C aerobically with 10% seeds-culture. The transformation rate from Na2SeO3 into SeNPs reached to 55.51%. After selenium enrichment, there were no significant morphology changes in C-1 cells but obvious SeNPs accumulated inside of cells, observed by scanning electron microscope and transmission electron microscope, verified by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. SeNPs had antioxidant activity in radical scavenge of superoxide (O2-), Hydroxyl radical (OH-) and 1,1-diphenyl-2-picryl-hydrazine (DPPH), where scavenging ability of OH- is the highest. Selenium-enriched C-1 had obvious anti-inflammatory effect in protecting integrity of Caco-2 cell membrane destroyed by S. typhimurium; it could preventing inflammatory damage in Caco-2 stressed by 200 μM H2O2 for 4 h, with significantly reduced expression of IL-8 (1.687 vs. 3.487, P = 0.01), IL-1β (1.031 vs. 5.000, P < 0.001), TNF-α (2.677 vs. 9.331, P < 0.001), increased Claudin-1 (0.971 vs. 0.611, P < 0.001) and Occludin (0.750 vs. 0.307, P < 0.001). Transcriptome data analysis showed that there were 381 differential genes in the vegetative growth stage and 1674 differential genes in the sporulation stage of C-1 with and without selenium-enrichment. A total of 22 ABC transporter protein-related genes at vegetative stage and 70 ABC transporter protein-related genes at sporulation stage were founded. Genes encoding MsrA, thiol, glutathione and thioredoxin reduction were significantly up-regulated; genes related to ATP synthase such as atpA and atpD genes showed down-regulated during vegetative stage; the flagellar-related genes (flgG, fliM, fliL, and fliJ) showed down-regulated during sporulation stage. The motility, chemotaxis and colonization ability were weakened along with synthesized SeNPs accumulated intracellular at sporulation stage. B. amyloliquefaciens C-1 could convert extracellular selenite into intracellular SeNPs through the oxidation-reduction pathway, with strong selenium-enriched metabolism. The SeNPs and selenium-enriched cells had potential to be developed as nano-selenium biomaterials and selenium-enriched postbiotics.

Impact of Biogenic and Chemogenic Selenium Nanoparticles on Model Eukaryotic Lipid Membranes

Microbial nanotechnology is an expanding research area devoted to producing biogenic metal and metalloid nanomaterials (NMs) using microorganisms. Often, biogenic NMs are explored as antimicrobial, anticancer, or antioxidant agents. Yet, most studies focus on their applications rather than the underlying mechanism of action or toxicity. Here, we evaluate the toxicity of our well-characterized biogenic selenium nanoparticles (bSeNPs) produced by the Stenotrophomonas maltophilia strain SeITE02 against the model yeast Saccharomyces cerevisiae comparing it with chemogenic SeNPs (cSeNPs). Knowing from previous studies that the biogenic extract contained bSeNPs in an organic material (OM) and supported here by Fourier transform infrared spectroscopy, we removed and incubated it with cSeNPs (cSeNPs_OM) to assess its influence on the toxicity of these formulations. Specifically, we focused on the first stages of the eukaryotic cell exposure to these samples─i.e., their interaction with the cell lipid membrane, which was mimicked by preparing vesicles from yeast polar lipid extract or phosphatidylcholine lipids. Fluidity changes derived from biogenic and chemogenic samples revealed that the bSeNP extract mediated the overall rigidification of lipid vesicles, while cSeNPs showed negligible effects. The OM and cSeNPs_OM induced similar modifications to the bSeNP extract, reiterating the need to consider the OM influence on the physical-chemical and biological properties of bSeNP extracts.

Biosynthesis of selenium nanoparticles by lactic acid bacteria and areas of their possible applications

Lactic acid bacteria, being generally recognized as safe, are the preferred choice among other microbial producers of selenium nanoparticles. For successful production of SeNPs, it is necessary to take into account the physiological properties of the bacterium used as a biotransformer of inorganic forms of selenium in Se⁰. The antimicrobial and antioxidant activity of SeNPs allows to use them in the form of pure nanoparticles or biomass of lactic acid bacteria enriched with selenium in preparation of food, in agriculture, aquaculture, medicine, veterinary, and manufacturing of packing materials for food products. To attract attention to the promising new directions of lactic acid bacteria applications and to accelerate their implementation, the examples of the use of SeNPs synthesized by lactic acid bacteria in the mentioned above areas of human activity are described.

Biosynthesized Silver Nanoparticles Derived from Probiotic Lactobacillus rhamnosus (AgNPs-LR) Targeting Biofilm Formation and Quorum Sensing-Mediated Virulence Factors

In recent years, bacterial pathogens have developed resistance to antimicrobial agents that have created a global threat to human health and environment. As a novel approach to combating antimicrobial resistance (AMR), targeting bacteria's virulent traits that can be explained by quorum sensing (QS) is considered to be one of the most promising approaches. In the present study, biologically synthesized silver nanoparticles derived from Lactobacillus rhamnosus (AgNPs-LR) were tested against three Gram-negative bacteria to determine whether they inhibited the formation of biofilms and triggered the virulence factors controlled by QS. In C. violaceum and S. marcescens, a remarkable inhibition (>70%) of QS-mediated violacein and prodigiosin production was recorded, respectively. A dose-dependent decrease in virulence factors of P. aeruginosa (pyocyanin, pyoverdine, LasA protease, LasB elastase and rhamnolipid production) was also observed with AgNPs-LR. The biofilm development was reduced by 72.56%, 61.70%, and 64.66% at highest sub-MIC for C. violaceum, S. marcescens and P. aeruginosa, respectively. Observations on glass surfaces have shown remarkable reductions in biofilm formation, with less aggregation of bacteria and a reduced amount of extra polymeric materials being formed from the bacteria. Moreover, swimming motility and exopolysaccharides (EPS) was also found to reduce in the presence of AgNPs-LR. Therefore, these results clearly demonstrate that AgNPs-LR is highly effective in inhibiting the development of biofilms and the QS-mediated virulent traits of Gram-negative bacteria. In the future, AgNPs-LR may be used as an alternative to conventional antibiotics for the treatment of bacterial infections after careful evaluation in animal models, especially for the development of topical antimicrobial agents.

Biogenic selenium nanoparticles alleviate intestinal epithelial barrier injury by regulating mitochondria-lysosome crosstalk

The intestinal epithelial barrier plays a fundamental role in human and animal health. Mitochondrial dysfunction can lead to intestinal epithelial barrier damage. The interaction between mitochondria and lysosomes has been proved to regulate each other's dynamics. Our previous studies have demonstrated that biogenic selenium nanoparticles (SeNPs) can alleviate intestinal epithelial barrier injury through regulating mitochondrial autophagy. In this study, we hypothesize that the protective effects of SeNPs against intestinal epithelial barrier dysfunction are associated with mitochondrial-lysosomal crosstalk. The results showed that lipopolysaccharide (LPS) and TBC1D15 siRNA transfection both caused the increase of intestinal epithelial permeability, activation of mitophagy, and mitochondrial and lysosomal dysfunction in porcine jejunal epithelial cells (IPEC-J2). SeNP pretreatment significantly up-regulated the expression levels of TBC1D15 and Fis1, down-regulated Rab7, caspase-3, MCOLN2 and cathepsin B expression levels, reduced cytoplasmic Ca²⁺ concentration, effectively alleviated mitochondrial and lysosomal dysfunction, and maintained the integrity of the intestinal epithelial barrier in IPEC-J2 cells exposed to LPS. Furthermore, SeNPs obviously reduced cytoplasmic Ca²⁺ concentration and activated the TBC1D15/Fis/Rab7-mediated signaling pathway, shortened the contact time between mitochondria and lysosomes, inhibited mitophagy, maintained mitochondrial and lysosomal homeostasis, and effectively attenuated intestinal epithelial barrier injury in IPEC-J2 cells transfected with TBC1D15 siRNA. These results indicated that the protective effect of SeNPs on intestinal epithelial barrier injury is closely associated with the TBC1D15/Rab7-mediated mitochondria-lysosome crosstalk signaling pathway.

Selenium-Enriched Probiotic Alleviates Western Diet-Induced Non-alcoholic Fatty Liver Disease in Rats via Modulation of Autophagy Through AMPK/SIRT-1 Pathway

Current study was aimed to investigate the ability of L.acidophilus SNZ 86 to biotransform inorganic selenium to a more active organic form, resulting in trace element enrichment. Selenium-enriched L. acidophilus SNZ 86 has been shown to be effective in the treatment of a variety of gastrointestinal illnesses, indicating the need for additional research to determine the full potential of this therapeutic strategy in the treatment of metabolic disorders. Herein, we employed the western style diet-induced model of non-alcoholic fatty liver disease (NAFLD) to explore the therapeutic effect of selenium-enriched probiotic (SP). Male Sprague Dawley rats (160-180 g) were fed a high-fat (58% Kcal of fat) and high-fructose (30% w/v) diet for 12 weeks to develop an animal model mimicking NAFLD. High-fat and High-fructose diet-fed rats exhibited hyperglycemia, hyperlipidemia, insulin resistance, abnormal liver function test, increased hepatic oxidative stress, and steatosis. SP was then administered orally (L acidophilus 1 × 10⁹ CFU/ml containing 0.4 g Se/day; p.o.) for 8 weeks. The selenium enrichment within L. acidophilus SNZ 86 was validated by TEM, which allowed for visualisation of the selenium deposition and size distribution in the probiotic. In NAFLD control rats, the expression of autophagy proteins (LC-3 A/B and Beclin), AMPK, and SIRT-1 was significantly reduced indicating downregulation of autophagy. However, supplementation of SP ameliorates hepatic steatosis as evidenced by improved biochemical markers and autophagic activation via upregulation of the AMPK and SIRT-1 pathway showing the relevance of autophagy in the disease aetiology. Collectively, these findings provide us with a better understanding of the role of SP in the treatment of hepatic steatosis and establish a therapeutic basis for potential clinical application of SP in the prevention of NAFLD and associated pathological conditions.

Biogenic Synthesis of Silver Nanoparticles Using Pantoea stewartii and Priestia aryabhattai and Their Antimicrobial, Larvicidal, Histopathological, and Biotoxicity Potential

In recent years, green nanotechnology has gained considerable importance for the synthesis of nanoparticles due to its economic viability and biosafety. In the current study, silver nanoparticles were synthesized using two bacterial isolates, H2 and H3, which were isolated from soil samples collected from the Western Ghats, Tamil Nadu, and identified at the species level as Pantoeastewartii (H2) and Priestiaaryabhattai (H3) by sequencing their 16s rRNA genes. Intracellularly synthesized silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy, atomic force microscopy, and particle size analysis. AFM studies show that both of the bacterial synthesized Ag NPs were circular-shaped and disaggregated, with an average size distribution of 4 nm for Pantoeastewartii and 3.6 nm for Priestiaaryabhattai. Furthermore, their larvicidal activity, antimicrobial, histopathological, and biotoxicity effects were determined. The synthesized Ag NPs exhibited potent larvicidal activity against fourth instars of Ae.aegypti, An.stephensi, and Cx.quinquefasciatus exposed to a 50 µg/mL concentration for 24 h based on their LC₅₀ and LC₉₀ values. Histopathological studies of the affected mosquito larvae clearly show damage to the epithelial cells, food bolus, basement membrane, muscles, and midgut parts. The maximum antimicrobial activity of Priestiaaryabhattai-synthesized Ag NPs was observed for Streptomyces varsoviensis MTCC-1537, and that of Pantoea stewartii-synthesized Ag NPs was against Escherichia coli MTCC-43. The toxicity test on non-target organisms such as Artemia nauplii and zebrafish embryos indicates no visible abnormalities or mortality after their exposure for 48h. It is concluded that silver nanoparticles can easily be synthesized using Pantoea stewartii (H2) and Priestia aryabhattai (H3) as capping and reducing agents. Silver nanoparticles showed potent larvicidal activities and could potentially be used in integrated vector control programs because they are safe for other inhabitants of the same aquatic environment as mosquito larvae.

Biogenic Selenium Nanoparticles in Biomedical Sciences: Properties, Current Trends, Novel Opportunities and Emerging Challenges in Theranostic Nanomedicine

Selenium is an important dietary supplement and an essential trace element incorporated into selenoproteins with growth-modulating properties and cytotoxic mechanisms of action. However, different compounds of selenium usually possess a narrow nutritional or therapeutic window with a low degree of absorption and delicate safety margins, depending on the dose and the chemical form in which they are provided to the organism. Hence, selenium nanoparticles (SeNPs) are emerging as a novel therapeutic and diagnostic platform with decreased toxicity and the capacity to enhance the biological properties of Se-based compounds. Consistent with the exciting possibilities offered by nanotechnology in the diagnosis, treatment, and prevention of diseases, SeNPs are useful tools in current biomedical research with exceptional benefits as potential therapeutics, with enhanced bioavailability, improved targeting, and effectiveness against oxidative stress and inflammation-mediated disorders. In view of the need for developing eco-friendly, inexpensive, simple, and high-throughput biomedical agents that can also ally with theranostic purposes and exhibit negligible side effects, biogenic SeNPs are receiving special attention. The present manuscript aims to be a reference in its kind by providing the readership with a thorough and comprehensive review that emphasizes the current, yet expanding, possibilities offered by biogenic SeNPs in the biomedical field and the promise they hold among selenium-derived products to, eventually, elicit future developments. First, the present review recalls the physiological importance of selenium as an oligo-element and introduces the unique biological, physicochemical, optoelectronic, and catalytic properties of Se nanomaterials. Then, it addresses the significance of nanosizing on pharmacological activity (pharmacokinetics and pharmacodynamics) and cellular interactions of SeNPs. Importantly, it discusses in detail the role of biosynthesized SeNPs as innovative theranostic agents for personalized nanomedicine-based therapies. Finally, this review explores the role of biogenic SeNPs in the ongoing context of the SARS-CoV-2 pandemic and presents key prospects in translational nanomedicine.

Allotropy of selenium nanoparticles: Colourful transition, synthesis, and biotechnological applications

Elemental selenium (Se⁰ ) nanomaterials undergo allotropic transition from thermodynamically-unstable to more stable phases. This process is significantly different when Se⁰ nanoparticles (NPs) are produced via physico-chemical and biological pathways. While the allotropic transition of physico-chemically synthesized Se⁰ is fast (minutes to hours), the biogenic Se⁰ takes months to complete. The biopolymer layer covering biogenic Se⁰ NPs might be the main factor controlling this retardation, but this still remains an open question. Phylogenetically-diverse bacteria reduce selenium oxyanions to red amorphous Se⁰ allotrope, which has low market value. Then, red Se⁰ undergoes allotropic transition to trigonal (metallic grey) allotrope, the end product having important industrial applications (e.g. semiconductors, alloys). Is it not yet clear whether biogenic Se⁰ presents any biological function, or it is mainly a detoxification and respiratory by-product. The better understanding of this transition would benefit the recovery of Se⁰ NPs from secondary resources and its targeted utilization with respect to each allotropic stage. This review article presents and critically discusses the main physico-chemical methods and biosynthetic pathways of Se⁰ (bio)mineralization. In addition, the article proposes a conceptual model for the resource recovery potential of trigonal selenium nanomaterials in the context of circular economy.

Biogenic metallic nanoparticles as enzyme mimicking agents

The use of biological systems such as plants, bacteria, and fungi for the synthesis of nanomaterials has emerged to fill the gap in the development of sustainable methods that are non-toxic, pollution-free, environmentally friendly, and economical for synthesizing nanomaterials with potential in biomedicine, biotechnology, environmental science, and engineering. Current research focuses on understanding the characteristics of biogenic nanoparticles as these will form the basis for the biosynthesis of nanoparticles with multiple functions due to the physicochemical properties they possess. This review briefly describes the intrinsic enzymatic mimetic activity of biogenic metallic nanoparticles, the cytotoxic effects of nanoparticles due to their physicochemical properties and the use of capping agents, molecules acting as reducing and stability agents and which aid to alleviate toxicity. The review also summarizes recent green synthetic strategies for metallic nanoparticles.

Rhizobium pusense-Mediated Selenium Nanoparticles-Antibiotics Combinations against Acanthamoeba sp

Severe ocular infections by Acanthamoeba sp. lead to keratitis, resulting in irreversible vision loss in immune-compromised individuals. When a protozoal infection spreads to neural tissues, it causes granulomatous encephalitis, which can be fatal. Treatment often takes longer due to the transition of amoeba from trophozoites to cyst stages, cyst being the dormant form of Acanthamoeba. A prolonged use of therapeutic agents, such as ciprofloxacin (Cipro), results in severe side effects; thus, it is critical to improve the therapeutic efficacy of these widely used antibiotics, possibly by limiting the drug-sensitive protozoal-phase transition to cyst formation. Owing to the biomedical potential of selenium nanoparticles (SeNPs), we evaluated the synergistic effects of ciprofloxacin and Rhizobium pusense-biogenic SeNPs combination. SeNPs synthesized using Rhizobium pusense isolated from root nodules were characterized using UV-Visible spectrophotometer, FT-IR, SEM with EDX, particle size analysis, and Zeta potential. The combination was observed to reduce the sub-lethal dose of Cipro, which may help reduce its side effects. The selenium and ciprofloxacin (SeNPs-Cipro) combination reduced the LC₅₀ by 33.43%. The anti-protozoal efficacy of SeNPs-Cipro was found to transduce through decreased protozoal-cyst formations and the inhibition of the galactosidase and protease enzymes of trophozoites. Furthermore, high leakage of sugar, proteins, and amino acids during the SeNPs-Cipro treatment was one primary reason for killing the trophozoites. These experimental results may be helpful in the further pre-clinical evaluation of SeNPs-Cipro to combat protozoal infections. Future studies for combinations of SeNPs with other antibiotics need to be conducted to know the potential of SeNPs against antibiotic resistance in Acanthamoeba.

Dietary supplementation with selenium nanoparticles-enriched Lactobacillus casei ATCC 393 alleviates intestinal barrier dysfunction of mice exposed to deoxynivalenol by regulating endoplasmic reticulum stress and gut microbiota

Deoxynivalenol (DON), a secondary product of Fusarium metabolism, is common in wheat, corn, barley and other grain crops, posing a variety of adverse effects to environment, food safety, human and animal health. The absorption of DON mainly occurs in the proximal part of the small intestine, which can induce intestinal mucosal epithelial injury, and ultimately affect the growth performance and production performance of animals. This study was conducted to investigate the protective effects of selenium nanoparticles (SeNPs)-enriched Lactobacillus casei ATCC 393 (L. casei ATCC 393) on intestinal barrier function of C57BL/6 mice exposed to DON and its association with endoplasmic reticulum stress (ERS) and gut microbiota. The results showed that DON exposure increased the levels of interleukin-6 (IL-6) and interleukin-8 (IL-8), decreased the levels of interleukin-10 (IL-10) and transforming growth factor beta (TGF-β), caused a redox imbalance and intestinal barrier dysfunction, decreased the mRNA levels of endoplasmic reticulum- resident selenoproteins, activated ERS-protein kinase R-like endoplasmic reticulum kinase (PERK) signaling pathway, altered the composition of the gut microbiota and decreased short-chain fatty acids (SCFAs) content. Dietary supplementation with SeNPs-enriched L. casei ATCC 393 can effectively protect the integrity of intestinal barrier function by reducing inflammatory response, enhancing the antioxidant capacity, up-regulating the mRNA levels of endoplasmic reticulum-resident selenoproteins, inhibiting the activation of PERK signaling pathway, reversing gut microbiota dysbiosis and increasing the content of SCFAs in mice exposed to DON. In conclusion, dietary supplementation with SeNPs-enriched L. casei ATCC 393 effectively alleviated intestinal barrier dysfunction induced by DON in C57BL/6 mice, which may be closely associated with the regulation of ERS and gut microbiota.

Biogenic Selenium Nanoparticles Synthesized by Lactobacillus casei ATCC 393 Alleviate Acute Hypobaric Hypoxia-Induced Intestinal Barrier Dysfunction in C57BL/6 Mice

Exposure to hypobaric hypoxia at high altitude will cause different tissue and organ damage over a long period of time. Studies have shown that hypobaric hypoxia can cause severe primary intestinal barrier dysfunction, and then cause multiple organ dysfunction. Our previous research showed that selenium nanoparticles (SeNPs) synthesized by Lactobacillus casei ATCC 393 (L. casei ATCC 393) can effectively alleviate intestinal barrier dysfunction caused by oxidative stress and inflammation in mice. This study was conducted to investigate the protective effect of biological SeNPs synthesized by L. casei ATCC 393 on intestinal barrier function in acute hypobaric hypoxic stress mice. The results showed that compared with the hypobaric hypoxic, the SeNPs synthesized by L. casei ATCC 393 by oral administration could effectively alleviate the shortening of intestinal villi, which decreased the level of diamine oxidase (DAO) and myeloperoxidase (MPO), and the expression level of tight junction protein in ileum was increased. In addition, SeNPs significantly increased the activities of superoxide dismutase (SOD), cyclooxygenase (COX-1) and glutathione peroxidase (GPx), and decreased the level of malondialdehyde (MDA), and inhibit the increase of hypoxia related factor. SeNPs effectively regulate the intestinal microecology disorder caused by hypobaric hypoxia stress, and maintain the intestinal microecology balance. In addition, oral administration of SeNPs had better protective effect on intestinal barrier function of mice under hypobaric hypoxia stress. These results suggested that SeNPs synthesized by L. casei ATCC 393 can effectively alleviate the damage of intestinal barrier function under acute hypobaric hypoxic stress, which may be closely related to the antioxidant activity of SeNPs.

Selenium Nanoparticles-Enriched Lactobacillus casei ATCC 393 Prevents Cognitive Dysfunction in Mice Through Modulating Microbiota-Gut-Brain Axis

Purpose

The bidirectional communication between the gut and the central nervous system mediated by gut microbiota is closely related to the occurrence and development of neurodegenerative diseases, including Alzheimer's disease (AD). Selenium (Se) has been identified as playing a role against AD. Probiotics have beneficial effects on host brain function and behavior by modulating the microbiota-gut-brain axis. Herein, we evaluated the protective effects of Lactobacillus casei ATCC 393 (L. casei ATCC 393) and selenium nanoparticles-enriched L. casei ATCC 393 (L. casei ATCC 393-SeNPs) against D-galactose/aluminum chloride-induced AD model mice.

Methods

The Morris Water Maze (MWM) test was used to assess cognitive function of mice. The morphology and histopathological changes, antioxidant capacity and immune responses in the brain and ileum were evaluated. The alterations in intestinal permeability of the mice were determined using FITC-dextran. Gut microbiota composition was assessed using 16s rRNA sequencing.

Results

Thirteen weeks intervention with L. casei ATCC 393 or L. casei ATCC 393-SeNPs significantly improved cognitive dysfunction, and minimized amyloid beta (Aβ) aggregation, hyperphosphorylation of TAU protein, and prevented neuronal death by modulating Akt/cAMP-response element binding protein (CREB)/brain-derived neurotrophic factor (BDNF) signaling pathway. Moreover, compared with L. casei ATCC 393, L. casei ATCC 393-SeNPs further effectively mitigated intestinal barrier dysfunction by improving antioxidant capacity, regulating immune response, restoring gut microbiota balance, and increasing the level of short-chain fatty acids and neurotransmitters, thereby inhibiting the activation of microglia and protecting brain neurons from neurotoxicity such as oxidative stress and neuroinflammation.

Conclusion

These findings indicated that targeting the microbiota-gut-brain axis with L. casei ATCC 393-SeNPs may have therapeutic potential for the deficits of cognitive function in the AD model mice. Thus, we anticipate that L. casei ATCC 393-SeNPs may be a promising and safe Se nutritional supplement for use as a food additive to prevent the neurodegenerative disease.

Antibiotic resistance in aquaculture and aquatic organisms: a review of current nanotechnology applications for sustainable management

Aquaculture has emerged as one of the world's fastest-growing food industries in recent years, helping food security and boosting global economic status. The indiscriminate disposal of untreated or improperly managed waste and effluents from different sources including production plants, food processing sectors, and healthcare sectors release various contaminants such as bioactive compounds and unmetabolized antibiotics, and antibiotic-resistant organisms into the environment. These emerging contaminants (ECs), especially antibiotics, have the potential to pollute the environment, particularly the aquatic ecosystem due to their widespread use in aquaculture, leading to various toxicological effects on aquatic organisms as well as long-term persistence in the environment. However, various forms of nanotechnology-based technologies are now being explored to assist other remediation technologies to boost productivity, efficiency, and sustainability. In this review, we critically highlighted several ecofriendly nanotechnological methods including nanodrug and vaccine delivery, nanoformulations, and nanosensor for their antimicrobial effects in aquaculture and aquatic organisms, potential public health risks associated with nanoparticles, and their mitigation measures for sustainable management.

Biogenic Selenium Nanoparticles and Their Anticancer Effects Pertaining to Probiotic Bacteria—A Review

Selenium nanoparticles (SeNPs) can be produced by biogenic, physical, and chemical processes. The physical and chemical processes have hazardous effects. However, biogenic synthesis (by microorganisms) is an eco-friendly and economical technique that is non-toxic to human and animal health. The mechanism for biogenic SeNPs from microorganisms is still not well understood. Over the past two decades, extensive research has been conducted on the nutritional and therapeutic applications of biogenic SeNPs. The research revealed that biogenic SeNPs are considered novel competitors in the pharmaceutical and food industries, as they have been shown to be virtually non-toxic when used in medical practice and as dietary supplements and release only trace amounts of Se ions when ingested. Various pathogenic and probiotic/nonpathogenic bacteria are used for the biogenic synthesis of SeNPs. However, in the case of biosynthesis by pathogenic bacteria, extraction and purification techniques are required for further useful applications of these biogenic SeNPs. This review focuses on the applications of SeNPs (derived from probiotic/nonpathogenic organisms) as promising anticancer agents. This review describes that SeNPs derived from probiotic/nonpathogenic organisms are considered safe for human consumption. These biogenic SeNPs reduce oxidative stress in the human body and have also been shown to be effective against breast, prostate, lung, liver, and colon cancers. This review provides helpful information on the safe use of biogenic SeNPs and their economic importance for dietary and therapeutic purposes, especially as anticancer agents.

Nanobiotechnological prospects of probiotic microflora: Synthesis, mechanism, and applications

Nanotechnology-driven solutions have almost touched every aspect of life, such as therapeutics, cosmetics, agriculture, and the environment. Physical and chemical methods for the synthesis of nanoparticles involve hazardous reaction conditions and toxic reducing as well as stabilizing agents. Hence, environmentally benign green routes are preferred to synthesize nanoparticles with tunable size and shape. Bacteria, fungi, algae, and medicinal plants are employed to synthesize gold, silver, copper, zinc, and other nanoparticles. However, very little literature is available on exploring probiotic bacteria for the synthesis of nanoparticles. In view of the background, this review gives the most comprehensive report on the nanobiotechnological potential of probiotic bacteria like Bacillus licheniformis, Bifidobacterium animalis, Brevibacterium linens, Lactobacillus acidophilus, Lactobacillus casei, and others for the synthesis of gold (AuNPs), selenium (SeNPs), silver (AgNPs), platinum (PtNPs), tellurium nanoparticles (TeNPs), zinc oxide (ZnONPs), copper oxide (CuONPs), iron oxide (Fe₃O₄NPs), and titanium oxide nanoparticles (TiO₂NPs). Both intracellular and extracellular synthesis are involved as potential routes for biofabrication of polydispersed nanoparticles that are spherical, rod, or hexagonal in shape. Capsular exopolysaccharide associated carbohydrates such as galactose, glucose, mannose, and rhamnose, cell membrane-associated diglycosyldiacylglycerol (DGDG), 1,2-di-O-acyl-3-O-[O-α-D-galactopyranosyl-(1 → 2)-α-d-glucopyranosyl]glycerol, triglycosyl diacylglycerol (TGDG), NADH-dependent enzymes, amino acids such as cysteine, tyrosine, and tryptophan, S-layer proteins (SLP), lacto-N-triose, and lactic acid play a significant role in synthesis and stabilization of the nanoparticles. The biogenic nanoparticles can be recovered by rational treatment with sodium dodecyl sulfate (SDS) and/or sodium hydroxide (NaOH). Eventually, diverse applications like antibacterial, antifungal, anticancer, antioxidant, and other associated activities of the bacteriogenic nanoparticles are also elaborated. Being more biocompatible and effective, probiotic-generated nanoparticles can be explored as novel nutraceuticals for their ability to ensure sustained release and bioavailability of the loaded bioactive ingredients for diagnosis, targeted drug delivery, and therapy.

Biogenic synthesis of selenium and tellurium nanoparticles by marine bacteria and their biological activity

Selenium (SeNPs) and tellurium nanoparticles (TeNPs) were synthesized by green technology using the three new bacterial marine isolates (strains PL 2476, AF 2469 and G 2451). Isolates were classified as Pseudoalteromonas shioyasakiensis according to 16S rRNA sequence analysis, morphological characteristics, and biochemical reactions. The bioreduction processes of isolates were studied in comparison with the previously described Alteromonas macleodii (strain 2328). All strains exhibited significant tolerance to selenite and tellurite up to 1000 µg/mL. A comparative analysis of the bioreduction processes of the isolates demonstrated that the strains have a high rate of reduction processes. Characterization of biogenic red SeNPs and black TeNPs using scanning electron microscopy (SEM), EDX analysis, Dynamic Light Scattering, and micro-Raman Spectroscopy revealed that all the isolates form stable spherical selenium and tellurium nanoparticles whose size as well as elemental composition depend on the producer strain. Nanoparticles of the smallest size (up to 100 nm) were observed only for strain PL 2476. Biogenic SeNPs and TeNPs were also characterized and tested for their antimicrobial, antifouling and cytotoxic activities. Significant antimicrobial activity was shown for nanoparticles at relatively high concentrations (500 and 1000 µg/mL), with the antimicrobial activity of TeNPs being more significant than SeNPs. In contrast, against cell cultures (breast cancer cells (SkBr3) and human dermal fibroblasts (HDF) SeNPs showed greater toxicity than tellurium nanoparticles. Studies have demonstrated the high antifouling effectiveness of selenium and tellurium nanoparticles when introduced into self-polishing coatings. According to the results obtained, the use of SeNPs and TeNPs as antifouling additives can reduce the concentration of leachable biocides used in coatings, reducing the pressure on the environment.

Potential role of selenium in alleviating obesity-related iron dyshomeostasis

Obesity is a serious health problem in modern life and increases the risk of many comorbidities including iron dyshomeostasis. In contrast to malnourished anemia, obesity-related iron dyshomeostasis is mainly caused by excessive fat accumulation, inflammation, and disordered gut microbiota. In obesity, iron dyshomeostasis also induces disorders associated with gut microbiota, neurodegenerative injury, oxidative damage, and fat accumulation in the liver. Selenium deficiency is often accompanied by obesity or iron deficiency, and selenium supplementation has been shown to alleviate obesity and overcome iron deficiency. Selenium inhibits fat accumulation and exhibits anti-inflammatory activity. It regulates gut microbiota, prevents neurodegenerative injury, alleviates oxidative damage to the body, and ameliorates hepatic fat accumulation. These effects theoretically meet the requirements for the inhibition of factors underlying obesity-related iron dyshomeostasis. Selenium supplementation may have a potential role in the alleviation of obesity-related iron dyshomeostasis. This review verifies this hypothesis in theory. All the currently reported causes and results of obesity-related iron dyshomeostasis are reviewed comprehensively, together with the effects of selenium. The challenges and strategies of selenium supplementation are also discussed. The findings demonstrate the possibility of selenium-containing drugs or functional foods in alleviating obesity-related iron dyshomeostasis.

Selenium Nanoparticles (SeNPs) Immunomodulation Is More Than Redox Improvement: Serum Proteomics and Transcriptomic Analyses

Selenium nanoparticles (SeNPs) are a novel elemental form selenium and often reported to possess beneficial bioactivities such as anticancer, promoting bone growth and immunomodulation. Our previous study demonstrated that chitosan-stabilized SeNPs have strong activity in immunomodulation. However, the mechanism underlying the immunomodulation of SeNPs is still unknown. The aim of this study is to identify the molecular mechanisms involved in SeNP-induced immunomodulation. Using zebrafish, as a common immunological animal model with a highly conserved molecular mechanism with other vertebrates, we conducted serum proteomic and tissue transcriptome analyses on individuals fed with SeNP in healthy or disease conditions. We also compared differences between SeNPs and an exogenous antioxidant Trolox in immune activity and redox regulation. Our results suggest that the immunomodulation activity was highly related to antioxidant activity and lipid metabolism. Interestingly, the biological functions enhanced by SeNP were almost identical in the healthy and disease conditions. However, while the SeNP was suppressing ROS in healthy individuals, it promoted ROS formation during disease condition. This might be related to the defense mechanism against pathogens. SOD and NFkβ appeared to be the key molecular switch changing effect of SeNPs when individuals undergo infection, indicating the close relationship between immune and redox regulation.

Dietary nano-selenium alleviated intestinal damage of juvenile grass carp (Ctenopharyngodon idella) induced by high-fat diet: Insight from intestinal morphology, tight junction, inflammation, anti-oxidization and intestinal microbiota

In recent years, high-fat diet (HFD) has been widely applied in aquaculture, which reduces the intestinal health of cultured fish. The current study evaluated the protective effects of nano-selenium (nano-Se) on intestinal health of juvenile grass carp (Ctenopharyngodon idella) fed with HFD. A total of 135 experimental fish were fed with a regular diet (Con), a HFD (HFD) and a HFD containing nano-Se at 0.6 mg/kg (HSe) for 10 weeks. The results showed that dietary nano-Se significantly improved the survival rate and feed efficiency which were reduced by HFD in juvenile grass carp (P < 0.05). Also, nano-Se (0.6 mg/kg) supplement alleviated intestinal damage caused by the HFD, thus maintaining the integrity of the intestine. Moreover, it significantly up-regulated the expression of genes related to tight junction (ZO-1, c laudin-3 and o ccludin), anti-oxidization (GPx4a andGPx4b), and the protein of ZO-1 in the intestine of juvenile grass carp, which were depressed by the HFD (P < 0.05). Furthermore, nano-Se supplementation significantly suppressed the expressions of genes related to the inflammation, including inflammatory cytokines (IL-8, IL-1β, IFN-γ, TNF-α and IL-6), signaling molecules (TLR4, p38 MAPK and NF-κB p65), and protein expression of NF-κB p65 and TNF-α in the intestine of juvenile grass carp which were induced by the HFD (P < 0.05). Besides, dietary nano-Se normalized the intestinal microbiota imbalance of juvenile grass carp caused by the HFD through increasing the abundance of the beneficial bacteria, e.g., Fusobacteria. Finally, dietary nano-Se increased the production of short chain fatty acids (SCFA) in the intestine, especially for butyric acid and caproic acid, which were negatively related to the increase of intestinal permeability and inflammation. In summary, supply of nano-Se (0.6 mg/kg) in HFD could effectively alleviate intestinal injury of juvenile grass carp by improving intestinal barrier function and reducing intestinal inflammation and oxidative stress. These positive effects may be due to the regulation of nano-Se on intestinal microbiota and the subsequently increased beneficial SCFA levels.

A bovine lactoferricin-lactoferrampin-encoding Lactobacillus reuteri CO21 regulates the intestinal mucosal immunity and enhances the protection of piglets against enterotoxigenic Escherichia coli K88 challenge

Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in human and animal. To determine the mechanism of a bovine lactoferricin-lactoferrampin (LFCA)-encoding Lactobacillus reuteri CO21 (LR-LFCA) to enhance the intestinal mucosal immunity, we used a newborn piglet intestine model to study the intestinal response to ETEC. Pigs were chosen due to the anatomical similarity between the porcine and the human intestine.4-day-old piglets were orally administered with LR-LFCA, LR-con (L. reuteri CO21 transformed with pPG612 plasmid) or phosphate buffered saline (PBS) for three consecutive days, within 21 days after these treatments, we found that LR-LFCA can colonize the intestines of piglets, improve the growth performance, enhance immune response and is beneficial for intestinal health of piglets by improving intestinal barrier function and modulating the composition of gut microbiota. Twenty-one days after, piglets were infected with ETEC K88 for 5 days, we found that oral administration of LR-LFCA to neonatal piglets attenuated ETEC-induced the weight loss of piglets and diarrhea incidence. LR-LFCA decreased the production of inflammatory factors and oxidative stress in intestinal mucosa of ETEC-infected piglets. Additionally, LR-LFCA increased the expression of tight junction proteins in the ileum of ETEC-infected piglets. Using LPS-induced porcine intestinal epithelial cells (IPEC-J2) in vitro, we demonstrated that LR-LFCA-mediated increases in the tight junction proteins might depend on the MLCK pathway; LR-LFCA might increase the anti-inflammatory ability by inhibiting the NF-κB pathway. We also found that LR-LFCA may enhance the antioxidant capacity of piglets by activating the Nrf2/HO-1 pathway. This study demonstrates that LR-LFCA is effective at maintaining intestinal epithelial integrity and host homeostasis as well as at repairing intestinal damage after ETEC infection and is thus a promising alternative therapeutic method for intestinal inflammation.

Impact of nanomaterials on the intestinal mucosal barrier and its application in treating intestinal diseases

The intestinal mucosal barrier (IMB) is one of the important barriers to prevent harmful substances and pathogens from entering the body environment and to maintain intestinal homeostasis. The dysfunction of the IMB is associated with intestinal diseases and disorders. Nanomaterials have been widely used in medicine and as drug carriers due to their large specific surface area, strong adsorbability, and good biocompatibility. In this review, we comprehensively discuss the impact of typical nanomaterials on the IMB and summarize the treatment of intestinal diseases by using nanomaterials. The effects of nanomaterials on the IMB are mainly influenced by factors such as the dosage, size, morphology, and surface functional groups of nanomaterials. There is huge potential and a broad prospect for the application of nanomaterials in regulating the IMB for achieving an optimal therapeutic effect for antibiotics, oral vaccines, drug carriers, and so on.

Effects of Supranutritional Selenium Nanoparticles on Immune and Antioxidant Capacity in Sprague-Dawley Rats

The present study was conducted to investigate the effects of supranutritional selenium nanoparticles (SeNPs) on immune and antioxidant capacity in rats. Forty male Sprague-Dawley (SD) rats were randomly divided into four groups and given intragastric administration of SeNPs at doses of 0, 0.2, 0.4, and 0.8 mg Se/kg BW, respectively, for 2 weeks. Serum immune parameters, serum and organic tissues (liver, heart, kidney) antioxidant indices, and liver mRNA expression of glutathione peroxidase 1 (GPx1) and glutathione peroxidase 4 (GPx4) were examined. The results showed that supranutritional doses of 0.4 and 0.8 mg Se/kg BW SeNPs promoted the immune responses in serum. SeNPs administration improved antioxidant capacity in the liver and kidney, and the best improvement on antioxidant capacity was found in the kidney. Furthermore, intragastric administration of SeNPs upregulated mRNA expression of GPx1 and GPx4 in the liver. The results obtained indicated that SeNPs administration at supranutritional levels had beneficial effects on immune and antioxidant capacity and supplemental SeNPs at dose of 0.4 mg Se/kg BW exhibited the best response in SD rats.

Protective Effects of Selenium Nanoparticle-Enriched Lactococcus lactis NZ9000 against Enterotoxigenic Escherichia coli K88-Induced Intestinal Barrier Damage in Mice

Composite microecological agents have received widespread attention due to their advantageous properties, including safety, multiple effects, and low cost. This study was conducted to evaluate the protective effects of selenium (Se) nanoparticle (SeNP)-enriched Lactococcus lactis NZ9000 (L. lactis NZ9000-SeNPs) against enterotoxigenic Escherichia coli (ETEC) K88-induced intestinal barrier damage in C57BL/6 mice. The oral administration of L. lactis NZ9000-SeNPs significantly increased the villus height and the number of goblet cells in the ileum; reduced the levels of serum and ileal interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ); and increased the activities of thioredoxin reductase (TrxR) and glutathione peroxidase (GSH-Px) compared with the ETEC K88-infected group not treated with L. lactis NZ9000-SeNPs. In addition, L. lactis NZ9000-SeNPs significantly attenuated the reduction of the expression levels of occludin and claudin-1, dysbiosis of the gut microbiome, and activation of the Toll-like receptor (TLR)/nuclear factor kappa B (NF-κB)-mediated signaling pathway induced by ETEC K88. These findings suggested that L. lactis NZ9000-SeNPs may be a promising and safe Se supplement for food or feed additives. IMPORTANCE The beneficial effects of microecological agents have been widely proven. Se, which is a nutritionally essential trace element for humans and animals, is incorporated into selenoproteins that have a wide range of pleiotropic effects, ranging from antioxidant to anti-inflammatory effects. However, sodium selenite, a common addition form of Se in feed and food, has disadvantages such as strong toxicity and low bioavailability. We investigated the protective effects of L. lactis NZ9000-SeNPs against ETEC K88-induced intestinal barrier injury in C57BL/6 mice. Our results show that L. lactis NZ9000-SeNPs effectively alleviate ETEC K88-induced intestinal barrier dysfunction. This study highlights the importance of developing a promising and safe Se supplement for the substitution of sodium selenite applied in food, feed, and biomedicine.

Enhanced lipid accumulation in microalgae through nanoparticle-mediated approach, for biodiesel production: A mini-review

Nanoparticle application in microalgae for enhanced lipid production is an ongoing work that leads towards the contribution in biodiesel production. During this decade, metal nanoparticles are constantly being reported to have numerous applications in diverse fields, because of their unique optical, electrical, and magnetic properties. They can interact with the biomolecules of cells and thereby alters cellular metabolisms, which in turn reflects their ability to regulate some primary or secondary metabolic pathways. Nanoparticles derived from metals like Fe, Cu, and Se are taking part in redox processes and their presence in many enzymes may modulate algal metabolisms. Besides by upregulating or downregulating the expression of several genes, nanoparticle exposure can alter gene expressions in many organisms. In microalgae such as Chlorella vulgaris, C. pyrenoidosa, Scenedesmus obliquus, S. rubescens, Trachydiscus minut u s, Parachlorella kessleri, and Tetraselmis suecica; metal nanoparticle exposure in different environmental conditions have impacts on various physiological or molecular changes, thereby increasing the growth rate, biomass and lipid production. The present mini-review gives an insight into the various advantages and a future outlook on the application of nanoparticles in microalgae for biofuel production. Also, it can be proposed that nanoparticles could be useful in blocking or deactivating the AGPase enzyme (involved in the glucose to starch conversion pathway), binding to its active site, thereby increasing lipid production in microalgae that could be utilized for enhanced biodiesel production.

Bacillus amyloliquefaciens SC06 Induced AKT-FOXO Signaling Pathway-Mediated Autophagy to Alleviate Oxidative Stress in IPEC-J2 Cells

Autophagy is a conserved proteolytic mechanism, which degrades and recycles damaged organs and proteins in cells to resist external stress. Probiotics could induce autophagy; however, its underlying molecular mechanisms remain elusive. Our previous study has found that BaSC06 could alleviate oxidative stress by inducing autophagy in rats. This research aimed to verify whether Bacillus amyloliquefaciens SC06 can induce autophagy to alleviate oxidative stress in IPEC-J2 cells, as well as explore its mechanisms. IPEC-J2 cells were first pretreated with 10⁸ CFU/mL BaSC06, and then were induced to oxidative stress by the optimal dose of diquat. The results showed that BaSC06 significantly triggered autophagy, indicated by the up-regulation of LC3 and Beclin1 along with downregulation of p62 in IPEC-J2 cells. Further analysis revealed that BaSC06 inhibited the AKT-FOXO signaling pathway by inhibiting the expression of p-AKT and p-FOXO and inducing the expression of SIRT1, resulting in increasing the transcriptional activity of FOXO3 and gene expression of the ATG5-ATG12 complex to induce autophagy, which alleviated oxidative stress and apoptosis. Taken together, BaSC06 can induce AKT-FOXO-mediated autophagy to alleviate oxidative stress-induced apoptosis and cell damage, thus providing novel theoretical support for probiotics in the prevention and treatment of oxidative damage.

Akkermansia muciniphila Exerts Strain-Specific Effects on DSS-Induced Ulcerative Colitis in Mice

Akkermansia muciniphila is a commensal bacterium of the gut mucus layer. Although both in vitro and in vivo data have shown that A. muciniphila strains exhibit strain-specific modulation of gut functions, its ability to moderate immunity to ulcerative colitis have not been verified. We selected three isolated human A. muciniphila strains (FSDLZ39M14, FSDLZ36M5 and FSDLZ20M4) and the A. muciniphila type strain ATCC BAA-835 to examine the effects of different A. muciniphila strains on dextran sulfate sodium-induced colitis. All of the A. muciniphila strains were cultured anaerobically in brain heart infusion medium supplemented with 0.25% type II mucin from porcine stomach. To create animal models, colitis was established in C57BL/6 mice which randomly divided into six groups with 10 mice in each group by adding 3% dextran sulfate sodium to drinking water for 7 days. A. muciniphila strains were orally administered to the mice at a dose of 1 × 10⁹ CFU. Only A. muciniphila FSDLZ36M5 exerted significant protection against ulcerative colitis (UC) by increasing the colon length, restoring body weight, decreasing gut permeability and promoting anti-inflammatory cytokine expression. However, the other strains (FSDLZ39M14, ATCC BAA-835 and FSDLZ20M4) failed to provide these effects. Notably, A. muciniphila FSDLZ20M4 showed a tendency to exacerbate inflammation according to several indicators. Gut microbiota sequencing showed that A. muciniphila FSDLZ36M5 supplementation recovered the gut microbiota of mice to a similar state to that of the control group. A comparative genomic analysis demonstrated that the positive effects of A. muciniphila FSDLZ36M5 compared with the FSDLZ20M4 strain may be associated with specific functional genes that are involved in immune defense mechanisms and protein synthesis. Our results verify the efficacy of A. muciniphila in improving UC and provide gene targets for the efficient and rapid screening of A. muciniphila strains with UC-alleviating effects.

The Advancing of Selenium Nanoparticles Against Infectious Diseases

Infectious diseases, caused by the direct exposure of cellular or acellular pathogens, are found to be closely associated with multiple inflammation and immune responses, keeping one of the top threats to human health. As an indispensable trace element, Selenium (Se) plays important roles in antioxidant defence and redox state regulation along with a variety of specific metabolic pathways. In recent decades, with the development of novel nanotechnology, Selenium nanoparticles (Se NPs) emerged as a promising agent for biomedical uses due to their low toxicity, degradability and high bioavailability. Taking the advantages of the strong ability to trigger apoptosis or autophagy by regulating reactive oxygen species (ROS), Se NPs have been widely used for direct anticancer treatments and pathogen killing/clearance in host cells. With excellent stability and drug encapsulation capacity, Se NPs are now serving as a kind of powerful nano-carriers for anti-cancer, anti-inflammation and anti-infection treatments. Notably, Se NPs are also found to play critical roles in immunity regulations, such as macrophage and T effector cell activation, which thus provides new possibilities to achieve novel nano-immune synergetic strategy for anti-cancer and anti-infection therapies. In this review, we summarized the progress of preparation methods for Se NPs, followed by the advances of their biological functions and mechanisms for biomedical uses, especially in the field of anti-infection treatments. Moreover, we further provide some prospects of Se NPs in anti-infectious diseases, which would be helpful for facilitating their future research progress for anti-infection therapy.

Clostridium butyricum Protects IPEC-J2 Cells from ETEC K88-Induced Oxidative Damage by Activating the Nrf2/ARE Signaling Pathway

Clostridium butyricum (CB) is a naturally occurring probiotic compound that can alleviate the oxidative damage induced by enterotoxigenic Escherichia coli K88 (ETEC K88) in porcine intestinal epithelial (IPEC-J2) cells. In this study, we investigate the molecular mechanism underlying this effect. Based on cell viability, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPX) assessments, the optimal concentration of ETEC K88 was determined to be 1 × 10³ cfu/mL. Viable bacteria counts in cells pretreated with CB and then infected with ETEC K88 show that CB can adhere to IPEC-J2 cells and that optimal adhesion is achieved at the multiple infection index (MOI) of 50 at 3 h of pretreatment. The results of qPCR indicate that although ETEC significantly decreases the expression levels of antioxidant enzymes regulated by NF-E2-related factor 2 (Nrf2) compared to the control group, CB reverses this effect. To confirm that Nrf2 is directly involved in the mechanism by which CB alleviates oxidative stress, siRNA was used to silence the expression of Nrf2 gene in IPEC-J2 cells. Compared to the NC+ETEC and siRNA+ETEC groups, the expressions of SOD1, SOD2, GPX1, and GPX2 in the NC+CB+ETEC and siRNA+CB+ETEC groups are significantly increased at 12 h and 24 h. This shows that CB can reduce ETEC K88-induced oxidative damage in IPEC-J2 cells by activating the expression of antioxidant enzymes implicated in the Kelch-like ECH-associated protein-1- (Keap1-) Nrf2/antioxidant response element (ARE) signaling pathway.

Recent development in Se-enriched yeast, lactic acid bacteria and bifidobacteria

Endemic selenium (Se) deficiency is a major worldwide nutritional challenge. Organic Se can be synthesized through physical and chemical methods that are conducive to human absorption, but its high production cost and low output cannot meet the actual demand for Se supplementation. Some microbes are known to convert inorganic Se into organic forms of high nutritional value and Se-enriched probiotics are the main representatives. The aim of the present review is to describe the characteristics of Se-enriched yeast, lactic acid bacteria, bifidobacteria and discuss their Se enrichment mechanisms. Se products metabolized by Se-enriched probiotics have been classified, such as Se nanoparticles (SeNPs) and selenoprotein, and their bioactivities have been assessed. The factors affecting the Se enrichment capacity of probiotics and their application in animal feed, food additives, and functional food production have been summarized. Moreover, a brief summary and the development of Se-enriched probiotics, particularly their potential applications in the field of biomedicine have been provided. In conclusion, Se-enriched probiotics not just have a wide range of applications in the food industry but also have great potential for application in the field of biomedicine in the future.

Characterization of Biosynthesized Silver Nanoparticles Using Lactobacillus rhamnosus GG and its In Vitro Assessment Against Colorectal Cancer Cells

Silver nanoparticles are the most desirable nanoparticles broadly used in diverse fields. This study intends to investigate the anticancer properties of synthesized silver/Lactobacillus rhamnosus GG nanoparticles (Ag-LNPs) as a reducing and stabilizing agent in the synthesis process. To prepare silver/Lactobacillus rhamnosus GG nanoparticles, 1 mg/ml cell lysate of Lactobacillus rhamnosus GG and 1 mM silver nitrate solution were mixed and incubated for 72 h. XRD, FTIR, and TEM methods were used for nanoparticle characterization. MTT assay and annexin/PI staining were employed to analyze the toxicity and apoptotic cells levels of Ag-LNPs, respectively. TEM showed that these nanoparticles are spherical shaped about 233 nm in size. FTIR spectroscopy demonstrated that Ag-LNPs were functionalized with biomolecules. XRD pattern showed high purity and face-centered crystal structure of Ag-LNPs. MTT assay revealed that the percentages of HT-29 live cells significantly reduced in the high concentration of Ag-LNPs. Annexin/PI staining showed that these nanoparticles could lead HT-29 cells to apoptosis. This study showed the new Ag-LNP-synthesizing method using Lactobacillus rhamnosus GG as a cost-effective and efficient approach. Also, it showed that these nanoparticles can be considered as a potential active agent for biomedical applications and drug delivery due to their anticancer activities.

Toward improved human health: efficacy of dietary selenium on immunity at the cellular level

Selenium, an essential trace element in the body, participates in various biological processes in the form of selenoproteins. In humans, a suitable concentration of selenium is essential for maintaining normal cellular function. Decreased levels of selenoproteins can lead to obstruction of the normal physiological functions of tissues and cells and even death. In addition, the level of selenium in the body affects cellular immunity, humoral immunity, and the balance between type 2 and type 1 helper T cells. Selenium can affect the immune function of the body through the reactive oxygen species (ROS), NF-κB, ferroptosis and NRF2 pathways. This paper reviews the immune effect of selenium on the body and the process of signal transduction and aims to serve as a reference for follow-up studies of immune function and research on the development of new selenium compounds and active targets.

Selenium in Human Health and Gut Microflora: Bioavailability of Selenocompounds and Relationship With Diseases

This review covers current knowledge of selenium in the dietary intake, its bioavailability, metabolism, functions, biomarkers, supplementation and toxicity, as well as its relationship with diseases and gut microbiota specifically on the symbiotic relationship between gut microflora and selenium status. Selenium is essential for the maintenance of the immune system, conversion of thyroid hormones, protection against the harmful action of heavy metals and xenobiotics as well as for the reduction of the risk of chronic diseases. Selenium is able to balance the microbial flora avoiding health damage associated with dysbiosis. Experimental studies have shown that inorganic and organic selenocompounds are metabolized to selenomethionine and incorporated by bacteria from the gut microflora, therefore highlighting their role in improving the bioavailability of selenocompounds. Dietary selenium can affect the gut microbial colonization, which in turn influences the host's selenium status and expression of selenoproteoma. Selenium deficiency may result in a phenotype of gut microbiota that is more susceptible to cancer, thyroid dysfunctions, inflammatory bowel disease, and cardiovascular disorders. Although the host and gut microbiota benefit each other from their symbiotic relationship, they may become competitors if the supply of micronutrients is limited. Intestinal bacteria can remove selenium from the host resulting in two to three times lower levels of host's selenoproteins under selenium-limiting conditions. There are still gaps in whether these consequences are unfavorable to humans and animals or whether the daily intake of selenium is also adapted to meet the needs of the bacteria.

Functional Food Product Based on Nanoselenium-Enriched Lactobacillus casei against Cadmium Kidney Toxicity

This paper demonstrates the ability of a functional food based on probiotics and selenium nanoparticles (SeNPs) to annihilate the toxic effect of cadmium on the kidneys. SeNPs were obtained by eco-friendly method used Lactobacillus casei. The morphological features and size of SeNPS were characterized by Atomic Force Microscopy (AFM) and Dynamic Light Scattering (DLS). Two kind of SeNPs were used, purified and Lacto-SeNPs (LSeNPs), administered by gavage at three concentrations (0.1, 0.2, and 0.4 mg/Kg b.w.) for 30 days in a mouse model of cadmium renal toxicity. The blood marker of renal injury (creatinine) significantly decreased in groups where the mice were treated with both form of SeNPs. The antioxidant capacity of plasma was evaluated by Trolox Equivalent Antioxidant Capacity (TEAC) assay and revealed that SeNPs in co-treatment with Cd, promotes maintaining antioxidant activity at the control level. Histopathological analysis of kidneys demonstrated morphological alteration in the group that received only cadmium and restored after administration of SeNPs or LSeNPs. In addition, immunohistochemical analysis revealed anti-apoptotic effects through reduction of pro-apoptotic bax and increasing of anti-apoptotic Bcl-2 protein expressions. Moreover, co-administration of Cd with SeNPs significantly decreased gene expression of kidneys inflammatory markers (TNF-α, IL-6, NF-ĸB) in a dose dependent manner, with the best results for LSeNPs at highest dose (0.4 mg/kg). Therefore, the L. casei strain is a potential SeNPs-enriched probiotic for application as functional food in the future to annihilate cadmium-induced kidneys toxicity.

Biogenic selenium nanoparticles produced by Lactobacillus casei ATCC 393 inhibit colon cancer cell growth in vitro and in vivo

Selenium compounds exhibit excellent anticancer properties but have a narrow therapeutic window. Selenium nanoparticles, however, are less toxic compared to other selenium forms, and their biogenic production leads to improved bioavailability. Herein, we used the probiotic strain Lactobacillus casei ATCC 393, previously shown to inhibit colon cancer cell growth, to synthesize biogenic selenium nanoparticles. We examined the anticancer activity of orally administered L. casei, L. casei-derived selenium nanoparticles and selenium nanoparticle-enriched L. casei, and investigated their antitumor potential in the CT26 syngeneic colorectal cancer model in BALB/c mice. Our results indicate that L. casei-derived selenium nanoparticles and selenium nanoparticle-enriched L. casei exert cancer-specific antiproliferative activity in vitro. Moreover, the nanoparticles were found to induce apoptosis and elevate reactive oxygen species levels in cancer cells. It is noteworthy that, when administered orally, selenium nanoparticle-enriched L. casei attenuated the growth of colon carcinoma in mice more effectively than the isolated nanoparticles or L. casei, suggesting a potential additive effect of the nanoparticles and the probiotic. To the best of our knowledge this is the first comparative study examining the anticancer effects of selenium nanoparticles synthesized by a microorganism, the selenium nanoparticle-enriched microorganism and the sole microorganism.

In Vivo Bioavailability of Selenium in Selenium-Enriched Streptococcus thermophilus and Enterococcus faecium in CD IGS Rats

The selenium (Se) enrichment of yeasts and lactic acid bacteria (LAB) has recently emerged as a novel concept; the individual health effects of these beneficial microorganisms are combined by supplying the essential micronutrient Se in a more bioavailable and less toxic form. This study investigated the bioavailability of Se in the strains Enterococcus faecium CCDM 922A (EF) and Streptococcus thermophilus CCDM 144 (ST) and their respective Se-enriched forms, SeEF and SeST, in a CD (SD-Sprague Dawley) IGS rat model. Se-enriched LAB administration resulted in higher Se concentrations in the liver and kidneys of rats, where selenocystine was the prevalent Se species. The administration of both Se-enriched strains improved the antioxidant status of the animals. The effect of the diet was more pronounced in the heart tissue, where a lower glutathione reductase content was observed, irrespective of the Se fortification in LAB. Interestingly, rats fed diets with EF and SeEF had higher glutathione reductase activity. Reduced concentrations of serum malondialdehyde were noted following Se supplementation. Diets containing Se-enriched strains showed no macroscopic effects on the liver, kidneys, heart, and brain and had no apparent influence on the basic parameters of the lipid metabolism. Both the strains tested herein showed potential for further applications as promising sources of organically bound Se and Se nanoparticles.

Physiological Characteristics of Lactobacillus casei Strains and Their Alleviation Effects against Inflammatory Bowel Disease

Lactobacillus casei, one of the most widely used probiotics, has been reported to alleviate multiple diseases. However, the effects of this species on intestinal diseases are strain-specific. Here, we aimed to screen L. casei strains with inflammatory bowel disease (IBD)-alleviating effects based on in vitro physiological characteristics. Therefore, the physiological characteristics of 29 L. casei strains were determined, including gastrointestinal transit tolerance, oligosaccharide fermentation, HT-29 cell adhesion, generation time, exopolysaccharide production, acetic acid production, and conjugated linoleic acid synthesis. The effects of five candidate strains on mice with induced colitis were also evaluated. The results showed that among all tested L. casei strains, only Lactobacillus casei M2S01 effectively relieved colitis. This strain recovered body weight, restored disease activity index score, and promoted anti-inflammatory cytokine expression. Gut microbiota sequencing showed that L. casei M2S01 restored a healthy gut microbiome composition. The western blotting showed that the alleviating effects of L. casei M2S01 on IBD were related to the inhibition of the NF-κB pathway. A good gastrointestinal tolerance ability may be one of the prerequisites for the IBDalleviating effects of L. casei. Our results verified the efficacy of L. casei in alleviating IBD and lay the foundation for the rapid screening of L. casei strain with IBD-alleviating effects.

Pediococcus pentosaceus ZJUAF-4 relieves oxidative stress and restores the gut microbiota in diquat-induced intestinal injury

Lactic acid bacteria (LAB) play a key role in promoting health and preventing diseases because of their beneficial effects, such as antimicrobial activities, modulating immune responses, maintaining the gut epithelial barrier and antioxidant capacity. However, the mechanisms with which LAB relieve oxidative stress and intestinal injury induced by diquat in vivo are poorly understood. In the present study, Pediococcus pentosaceus ZJUAF-4 (LAB, ZJUAF-4), a selected probiotics strain with strong antioxidant capacities, was appointed to evaluate the efficiency against oxidative stress in diquat-induced intestinal injury of mice. Alanine transaminase (ALT) and aspartate aminotransferase (AST) were analyzed to estimate the liver injury. The intestinal permeability was evaluated by 4 kDa fluorescein isothiocyanate (FITC)-dextran (FD4), D-lactate (DLA), and diamine oxidase (DAO) levels. Jejunum reactive oxygen species (ROS) production was examined by dihydroethidium (DHE) staining. Western blotting was used to detect the expression of nuclear factor (erythroid-derived-2)-like 2 (Nrf2) and its downstream genes in jejunum. The gut microbiota was analyzed by high-throughput sequencing method based on the 16S rRNA genes. The results showed that ZJUAF-4 pretreatment was found to protect the intestinal barrier function and maintain intestinal redox homeostasis under diquat stimulation. Moreover, oral administration of ZJUAF-4 increased the expression of Nrf2 and its downstream genes. High-throughput sequencing analysis indicated that ZJUAF-4 contributed to restoring the gut microbiota influenced by diquat. Our results suggested that ZJUAF-4 protected the intestinal barrier from oxidative stress-induced damage by modulating the Nrf2 pathway and gut microbiota, indicating that ZJUAF-4 may have potential applications in preventing and treating oxidative stress-related intestinal diseases. KEY POINTS: • ZJUAF-4 exerted protective effects against diquat-induced intestinal injury. • Activation of Nrf2 and its downstream targets towards oxidative stress. • ZJUAF-4 administration restoring gut microbiota.

Green Synthesis of Selenium and Tellurium Nanoparticles: Current Trends, Biological Properties and Biomedical Applications

The synthesis and assembly of nanoparticles using green technology has been an excellent option in nanotechnology because they are easy to implement, cost-efficient, eco-friendly, risk-free, and amenable to scaling up. They also do not require sophisticated equipment nor well-trained professionals. Bionanotechnology involves various biological systems as suitable nanofactories, including biomolecules, bacteria, fungi, yeasts, and plants. Biologically inspired nanomaterial fabrication approaches have shown great potential to interconnect microbial or plant extract biotechnology and nanotechnology. The present article extensively reviews the eco-friendly production of metalloid nanoparticles, namely made of selenium (SeNPs) and tellurium (TeNPs), using various microorganisms, such as bacteria and fungi, and plants' extracts. It also discusses the methodologies followed by materials scientists and highlights the impact of the experimental sets on the outcomes and shed light on the underlying mechanisms. Moreover, it features the unique properties displayed by these biogenic nanoparticles for a large range of emerging applications in medicine, agriculture, bioengineering, and bioremediation.