Selenium nanomaterials in biomedicine—An overview of new opportunities in nanomedicine of selenium

pH responsive fabrication of PVA-stabilized selenium nano formulation encapsulated with luteolin to reduce diabetic ureteral injury by decreasing NLRP3 inflammasome via Nrf2/ARE signaling

Diabetic ureteral injury (DUI) is a condition characterized by damage to the ureter, causing functional and morphological changes in the urinary system, which have a significant impact on a quality of life and requires appropriate medical treatment. The present study describes to novel design of luteolin (LT), a type of natural flavonoid, encapsulated selenium nanoparticles (Se NPs) to attain therapeutic potential for DUI. The physico-chemical characterizations of prepared Se NPs have benefitted zeta potential (-18 mV) and particle size (10-50 nm). In vitro assays were demonstrated the potential of LT-SeNPs by HEK 293 cells stimulated by STZ for DUI. Cytotoxicity assays on HEK 293 and NIH-3T3 showed >90% cell viability, which demonstrates the suitability of the nanoformulation for DUI treatment. The LT-SeNPs significantly inhibits the NLRP3 inflammasome through Nrf2/ARE pathway, which benefits for DUI treatment. The developed LT-SeNPs could be an effective formulation for the DUI therapy.

Insight into selenium biofortification and the selenite metabolic mechanism of Monascus ruber M7

Monascus species are functional fermentation fungi with great potential for selenium (Se) supplementation. This study investigated the effects of Se bio-fortification on the growth, morphology, and biosynthesis of Monascus ruber M7. The results demonstrated a significant increase in the yield of orange and red Monascus pigments (MPs) in red yeast rice (RYR) by 38.52% and 36.57%, respectively, under 20 μg/mL of selenite pressure. Meanwhile, the production of citrinin (CIT), a mycotoxin, decreased from 244.47 μg/g to 175.01 μg/g. Transcriptome analysis revealed significant upregulation of twelve genes involved in MPs biosynthesis, specifically MpigE, MpigF, and MpigN, and downregulation of four genes (mrr3, mrr4, mrr7, and mrr8) associated with CIT biosynthesis. Additionally, three genes encoding cysteine synthase cysK (Log2FC = 1.6), methionine synthase metH (Log2FC = 2.2), and methionyl-tRNA synthetase metG (Log2FC = 1.8) in selenocompound metabolism showed significantly upregulated. These findings provide insights into Se biotransformation and metabolism in filamentous fungi.

Nano-Formulations of Natural Antioxidants for the Treatment of Liver Cancer

Oxidative stress is a key factor in the pathological processes that trigger various chronic liver diseases, and significantly contributes to the development of hepatocarcinogenesis. Natural antioxidants reduce oxidative stress by neutralizing free radicals and play a crucial role in the treatment of free-radical-induced liver diseases. However, their efficacy is often limited by poor bioavailability and metabolic stability. To address these limitations, recent advances have focused on developing nano-drug delivery systems that protect them from degradation and enhance their therapeutic potential. Among the several critical benefits, they showed to be able to improve bioavailability and targeted delivery, thereby reducing off-target effects by specifically directing the antioxidant to the liver tumor site. Moreover, these nanosystems led to sustained release, prolonging the therapeutic effect over time. Some of them also exhibited synergistic effects when combined with other therapeutic agents, allowing for improved overall efficacy. This review aims to discuss recent scientific advances in nano-formulations containing natural antioxidant molecules, highlighting their potential as promising therapeutic approaches for the treatment of liver cancer. The novelty of this review lies in its comprehensive focus on the latest developments in nano-formulations of natural antioxidants for the treatment of liver cancer.

Reprogramming Tumor-Associated Macrophages with a Se-Based Core-Satellite Nanoassembly to Enhance Cancer Immunotherapy

Tumor-associated macrophages (TAMs), as the most prevalent immune cells in the tumor microenvironment, play a pivotal role in promoting tumor development through various signaling pathways. Herein, we have engineered a Se@ZIF-8 core-satellite nanoassembly to reprogram TAMs, thereby enhancing immunotherapy outcomes. When the nanoassembly reaches the tumor tissue, selenium nanoparticles and Zn2+ are released in response to the acidic tumor microenvironment, resulting in a collaborative effort to promote the production of reactive oxygen species (ROS). The generated ROS, in turn, activate the nuclear factor κB (NF-κB) signaling pathway, driving the repolarization of TAMs from M2-type to M1-type, effectively eliminating cancer cells. Moreover, the nanoassembly can induce the immunogenic death of cancer cells through excess ROS to expose calreticulin and boost macrophage phagocytosis. The Se@ZIF-8 core-satellite nanoassembly provides a potential paradigm for cancer immunotherapy by reversing the immunosuppressive microenvironment.

Polylevodopa nanoplatform for lateral flow immunochromatography assay of SARS-CoV-2 and influenza A virus

At the end of 2019, an unprecedented outbreak of novel coronavirus pneumonia ravaged the global landscape, inflicting profound harm upon society. Following numerous cycles of transmission, we find ourselves in an epoch where the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) coexists alongside influenza viruses (Flu A). Swift and accurate diagnosis of SARS-CoV-2 and Flu A is imperative to stem the spread of these maladies and administer appropriate treatment. Presently, colloidal gold-based lateral flow immunoassays (Au-LFIAs) constructed through electrostatic adsorption are beset by challenges such as diminished sensitivity and feeble binding stability. In this context, we propose the adoption of black polylevodopa nanoparticles (PLDA NPs) featuring abundant carboxyl groups as labeling nanomaterials in LFIA to bolster the stability and sensitivity of SARS-CoV-2 antigens and influenza A virus identifications. The engineered PLDA-LFIAs exhibit the capacity to detect SARS-CoV-2 and Flu A within 30 min, boasting a detection threshold of 5 pg/ml for the SARS-CoV-2 antigen and 0.1 ng/ml for the Flu A H1N1 antigen, thereby underscoring their heightened sensitivity relative to Au-LFIAs. These PLDA-LFIAs hold promise for the early detection of SARS-CoV-2 and Flu A, underscoring the potential of PLDA NPs as a discerning labeling probe to heighten the sensitivity of LFIA across diverse applications.

Microflora structure and functional capacity in Tibetan kefir grains and selenium-enriched Tibetan kefir grains: A metagenomic analysis

Tibetan kefir grains (TKGs) are a complex protein-lipid-polysaccharide matrix composed of various microorganisms. Microorganisms have the benefit of being effective, secure, and controllable when used for selenium enrichment. In this study, selenium-enriched Tibetan kefir grains (Se-TKGs) were made, and the microbiology composition was analyzed through a metagenomic analysis, to explore the influence of selenium enrichment. The microbial composition of TKGs and Se-TKGs, as well as the probiotic species, quorum sensing system (QS) and functional genes were compared and evaluated. Lactobacillus kefiranofaciens was the most abundant microbial species in both communities. Compared with TKGs, Se-TKGs had a much higher relative abundance of acetic acid bacteria. Lactobacillus helveticus was the most common probiotic species both in TKGs and Se-TKGs. Probiotics with antibacterial and anti-inflammatory properties were more abundant in Se-TKGs. QS analysis revealed that Se-TKGs contained more QS system-associated genes than TKGs. Moreover, Kyoto Encyclopedia of Genes and Genomes analysis revealed that the pathway for human disease ko01501 had the greatest relative abundance in both TKGs and Se-TKGs. Compared with TKGs, Se-TKGs demonstrated a greater relative abundance of different drug resistance-related metabolic pathways. Additionally, linear discriminant analysis effect size was used to examine the biomarkers responsible for the difference between the two groups. In this study, we focused on the microbiological structure of TKGs and Se-TKGs, with the aim of establishing a foundation for a more thorough investigation of Se-TKGs and providing a basis for exploring potential future use.

Unravelling the in vitro and in vivo potential of selenium nanoparticles in Alzheimer's disease: A bioanalytical review

Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by progressive cognitive decline and the accumulation of beta-amyloid plaques and tau tangles in the brain. Current therapies have limited efficacy, prompting the search for novel treatments. Selenium nanoparticles (SeNPs) have emerged as promising candidates for AD therapy due to their unique physicochemical properties and potential therapeutic effects. This review provides an overview of SeNPs and their potential application in AD treatment, as well as the main bioanalytical techniques applied in this field. SeNPs possess antioxidant and anti-inflammatory properties, making them potential candidates to combat the oxidative stress and neuroinflammation associated with AD. Moreover, SeNPs have shown the ability to cross the blood-brain barrier (BBB), allowing them to target brain regions affected by AD pathology. Various methods for synthesizing SeNPs are explored, including chemical, physical and biological synthesis approaches. Based on the employment of algae, yeast, fungi, and plants, green methods offer a promising and biocompatible alternative for SeNPs production. In vitro studies have demonstrated the potential of SeNPs in reducing beta-amyloid aggregation and inhibiting tau hyperphosphorylation, providing evidence of their neuroprotective effects on neuronal cells. In vivo studies using transgenic mouse models and AD-induced symptoms have shown promising results, with SeNPs treatment leading to cognitive improvements and reduced amyloid plaque burden in the hippocampus. Looking ahead, future trends in SeNPs research involve developing innovative brain delivery strategies to enhance their therapeutic potential, exploring alternative animal models to complement traditional mouse studies, and investigating multi-targeted SeNPs formulations to address multiple aspects of AD pathology. Overall, SeNPs represent a promising avenue for AD treatment, and further research in this field may pave the way for effective and much-needed therapeutic interventions for individuals affected by this debilitating disease.

Superoxide Dismutase Catalyzed Size-Adjustable Selenium Nanoparticles in Saccharomyces boulardii

Selenium nanoparticles (SeNPs) are important and safe food and feed additives that can be used for dietary supplementation. In this study, a mutagenic strain of Saccharomyces boulardii was employed to obtain biologically synthesized SeNPs (BioSeNPs) with the desired particle size by controlling the dosage and duration of sodium selenite addition, and the average particle size achieved was 55.8 nm with protease A encapsulation. Transcriptomic analysis revealed that increased expression of superoxide dismutase 1 (SOD1) in the mutant strain effectively promoted the synthesis of BioSeNPs and the formation of smaller nanoparticles. Under sodium selenite stress, the mutant strain exhibited significantly increased expression of glutathione peroxidase 2 (GPx2), which was significantly greater in the mutant strain than in the wild type, facilitating the synthesis of glutathione selenol and providing abundant substrates for the production of BioSeNPs. Furthermore, based on the experimental results and transcriptomic analysis of relevant genes such as sod1, gpx2, the thioredoxin reductase 1 gene (trr1) and the thioredoxin reductase 2 gene (trr2), a yeast model for the size-controlled synthesis of BioSeNPs was constructed. This study provides an important theoretical and practical foundation for the green synthesis of controllable-sized BioSeNPs or other metal nanoparticles with potential applications in the fields of food, feed, and biomedicine.

Recent Progress in Sulfur-Containing High Refractive Index Polymers for Optical Applications

The development in the field of high refractive index materials is a crucial factor for the advancement of optical devices with advanced features such as image sensors, optical data storage, antireflective coatings, light-emitting diodes, and nanoimprinting. Sulfur plays an important role in high refractive index applications owing to its high molar refraction compared to carbon. Sulfur exists in multiple oxidation states and can exhibit various stable functional groups. Over the last few decades, sulfur-containing polymers have attracted much attention owing to their wide array of applications governed by the functional group of sulfur present in the polymer repeat unit. The interplay of refractive index and various other polymer properties contributes to successfully implementing a specific polymer material in optical applications. The focus on developing optoelectronic devices induced an ever-increasing need to integrate different functional materials to achieve the devices' full potential. Several devices that see the potential use of sulfur in high refractive index materials are reviewed in the study. Like sulfur, selenium also exhibits high molar refraction and unique chemical properties, making it an essential field of study. This review covers the research and development in the field of sulfur and selenium in different forms of functionality, focusing on the chemistry of bonding and the optical properties of the polymers containing the heteroatoms mentioned above. The strategy and rationale behind incorporating heteroatoms in a polymer matrix to produce high-refractive-index materials are also described in the present review.

Effect of Administration of Selenium Nanoparticles Synthesized Using Onion Extract on Biochemical and Inflammatory Parameters in Mice Fed with High-Fructose Diet: In Vivo and In Silico Analysis

Fructose consumption has increased globally and has been linked to obesity, insulin resistance, and diabetes. Selenium nanoparticles (SeNPs) can regulate glucose and lipid concentrations and have immunoregulatory properties. Four study groups (n = 7/group) of eight-week-old male mice (Balb/c) were formed for this investigation. One group received a standard diet (C), another standard diet plus SeNPs (C + SeNPs), a high fructose diet (F), and a group with a high fructose diet plus SeNPs (F + SeNPs). Weight, glucose, triglycerides, and cholesterol were evaluated. In the end, mice were sacrificed, blood samples were obtained to assess cytokine profile, and liver, kidney, and pancreas were removed for histological examination. The study was complemented with an in silico analysis where the CTD, STITCH, ToppGene Suite, ShinyGO 0.76.3 databases, and Cytoscape software were implemented. The results of in vivo analysis showed that SeNPs regulated biochemical parameters and showed anti-inflammatory effects by decreasing the concentrations of TNF-alpha, IL-1beta, and IFN-gamma and increasing IL-10. No damage was observed in the studied organs. In addition, SeNPs regulate oxidative stress, preserve cell organelles, and regulate metabolic pathways to avoid the adverse effects of fructose consumption, according to bioinformatics analysis. In conclusion, SeNPs protect against the undesirable effects of a diet rich in fructose.

Selenium bio-nanocomposite based on extracellular polymeric substances (EPS): Synthesis, characterization and application in alleviating cadmium toxicity in rice (Oryza sativa L.)

Selenium nanoparticles (SeNPs) have gained significant attention owing to their favorable bioavailability and low toxicity, making them widely applications in the fields of medicine, food and agriculture. In this study, bacterial extracellular polymeric substances (EPS) were used as a novel stabilizer and capping agent to prepare dispersed SeNPs. Results show that EPS-SeNPs presented negative potential (-38 mV), spherical morphologies with average particle size about 100-200 nm and kept stable at room temperature for a long time. X-ray diffraction (XRD) analysis demonstrated that the synthesized nanoparticles were pure amorphous nanoparticles, and X-ray photoelectron spectroscopy (XPS) spectrum showed a spike at 55.6 eV, indicating the presence of zero-valent nano‑selenium. Fourier-transform infrared spectroscopy (FTIR) and three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy analysis confirmed proteins and polysaccharides in EPS played a crucial role in the synthesis of EPS-SeNPs. Compared to EPS or sodium selenite (Na2SeO3), EPS-SeNPs showed a relatively moderate result in terms of scavenging free radicals in vitro. In contrast, EPS-SeNPs demonstrated lower toxicity to rice seeds than Na2SeO3. Notably, the exogenous application of EPS-SeNPs effectively alleviated the growth inhibition and oxidative damaged caused by cadmium (Cd), and significantly reduced Cd accumulation in rice plants.

Selenium - An environmentally friendly micronutrient in agroecosystem in the modern era: An overview of 50-year findings

Agricultural productivity is constantly being forced to maintain yield stability to feed the enormously growing world population. However, shrinking arable and nutrient-deprived soil and abiotic and biotic stressor (s) in different magnitudes put additional challenges to achieving global food security. Though well-defined, the concept of macro, micronutrients, and beneficial elements is from a plant nutritional perspective. Among various micronutrients, selenium (Se) is essential in small amounts for the life cycle of organisms, including crops. Selenium has the potential to improve soil health, leading to the improvement of productivity and crop quality. However, Se possesses an immense encouraging phenomenon when supplied within the threshold limit, also having wide variations. The supplementation of Se has exhibited promising outcomes in lessening biotic and abiotic stress in various crops. Besides, bulk form, nano-Se, and biogenic-Se also revealed some merits and limitations. Literature suggests that the possibilities of biogenic-Se in stress alleviation and fortifying foods are encouraging. In this article, apart from adopting a combination of a conventional extensive review of the literature and bibliometric analysis, the authors have assessed the journey of Se in the "soil to spoon" perspective in a diverse agroecosystem to highlight the research gap area. There is no doubt that the time has come to seriously consider the tag of beneficial elements associated with Se, especially in the drastic global climate change era.

Spatially varying relationships of soil Se concentration and rice Se concentration in Guangxi, China: A geographically weighted regression approach

In recent years, the biogeochemical behavior and environmental impact of Selenium (Se) on soil-plant systems have received widespread attention, and traditional statistical methods reveal generally positive correlations between rice Se and soil Se. However, that initial positive relationship may have been obscured by local external factors. Using local scale data from the geochemical evaluation of land quality project, this work employed geographically weighted regression (GWR) to examine the spatial variation of rice Se (as the dependent variable) and soil Se (as the independent variable) in Guangxi. Strong and weak correlation coefficients occur between rice Se and soil Se, thereby indicating that their relationships are spatially varying. Guangxi is characterized by significantly positive correlations in most areas, with weak correlations mostly found in the south-western and central-eastern regions. Areas with weak correlation can be divided into two patterns: high soil Se with low rice Se and high rice Se with low soil Se. The unique patterns are correlated with distinct natural factors, particularly the abundance of Fe-rich soils in the carbonate area; by contrast, sandstone areas in central Guangxi may have been affected by anthropogenic activities. To reveal the spatially varying relationships at the local scale, we employed GWR, an effective tool that allowed us to identify the association between environmental variables and influencing factors and explore spatially varying relationships between them. This study breaks through the existing understanding that soil Se is completely positively correlated with rice Se for the first time, and concludes that their correlation is spatially variable, providing an effective approach for the study of complex relationships.

Advances in the Study of Selenium-Enriched Probiotics: From the Inorganic Se into Se Nanoparticles

Selenium (Se) is a momentous metallic element that plays an irreplaceable role in biochemical activities. Se deficiency remains a nutritional challenge across the world. Organic Se supplementation is the most effective treatment means for Se deficiency. Organic Se transformed from Se-enriched probiotics show outstanding excellent properties in antibacteria, anti-oxidation, anti-inflammation, and immunoregulation. Studying the influencing factors for Se enrichment capacity and enrichment mechanisms of Se-enriched probiotics is conducive to the exploit of more potent Se-enriched probiotics. Se-enriched probiotics transform inorganic Se into Se nanoparticles (SeNPs), which have been widely used in animal husbandry and biomedical field. In this paper, the novel development of Se-enriched probiotics is reviewed, and the bioactivities of SeNPs are assessed, so as to display their potential application prospects. The excellent role of SeNPs in anti-oxidation is summarized, and the mechanism by which SeNPs improve Se deficiency and boost animal health is explained.

Selenium nanoparticles: Enhanced nutrition and beyond

Selenium is a trace nutrient that has both nutritional and nutraceutical functions, whereas narrow nutritional range of selenium intake limits its use. Selenium nanoparticles (SeNPs) are less toxic and more bioavailable than traditional forms of selenium, suggesting that SeNPs have the potential to replace traditional selenium in food industries and/or biomedical fields. From the perspective of how SeNPs can be applied in health area, this review comprehensively discusses SeNPs in terms of its preparation, nutritional aspect, detoxification effect of heavy metals, nutraceutical functions and anti-pathogenic microorganism effects. By physical, chemical, or biological methods, inorganic selenium can be transformed into SeNPs which have increased stability and bioavailability as well as low toxicity. SeNPs are more effective than traditional selenium form in synthesizing selenoproteins like glutathione peroxidases. SeNPs can reshape the digestive system to facilitate digestion and absorption of nutrients. SeNPs have shown excellent potential to adjunctively treat cancer patients, enhance immune system, control diabetes, and prevent rheumatoid arthritis. Additionally, SeNPs have good microbial anti-pathogenic effects and can be used with other antimicrobial agents to fight against pathogenic bacteria, fungi, or viruses. Development of novel SeNPs with enhanced functions can greatly benefit the food-, nutraceutical-, and biomedical industries.

Antimicrobial and anti-viral effects of selenium nanoparticles and selenoprotein based strategies: COVID-19 and beyond

Deficiency of selenium (Se) has been described in a significant number of COVID-19 patients having a higher incidence of mortality, which makes it a pertinent issue to be addressed clinically for effective management of the COVID-19 pandemic. Se nanoparticles (SeNPs) provide a unique option for managing the havoc caused by the COVID-19 pandemic. SeNPs possess promising anti-inflammatory and anti-fibrotic effects by virtue of their nuclear factor kappa-light-chain-stimulator of activated B cells (NFκB), mitogen-activated protein kinase (MAPKs), and transforming growth factor-beta (TGF-β) modulatory activity. In addition, SeNPs possess remarkable immunomodulatory effects, making them a suitable option for supplementation with a much lower risk of toxicity compared to their elemental counterpart. Further, SeNPs have been shown to curtail viral and microbial infections, thus, making it a novel means to halt viral growth. In addition, it can be administered in the form of aerosol spray, direct injection, or infused thin-film transdermal patches to reduce the spread of this highly contagious viral infection. Moreover, a considerable decrease in the expression of selenoprotein along with enhanced expression of IL-6 in COVID-19 suggests a potential association among selenoprotein expression and COVID-19. In this review, we highlight the unique antimicrobial and antiviral properties of SeNPs and the immunomodulatory potential of selenoproteins. We provide the rationale behind their potentially interesting properties and further exploration in the context of microbial and viral infections. Further, the importance of selenoproteins and their role in maintaining a successful immune response along with their association to Se status is summarized.

A review on synthesis and antibacterial potential of bio-selenium nanoparticles in the food industry

Effective control of foodborne pathogen contamination is a significant challenge to the food industry, but the development of new antibacterial nanotechnologies offers new opportunities. Notably, selenium nanoparticles have been extensively studied and successfully applied in various food fields. Selenium nanoparticles act as food antibacterial agents with a number of benefits, including selenium as an essential trace element in food, prevention of drug resistance induction in foodborne pathogens, and improvement of shelf life and food storage conditions. Compared to physical and chemical methods, biogenic selenium nanoparticles (Bio-SeNPs) are safer and more multifunctional due to the bioactive molecules in Bio-SeNPs. This review includes a summarization of (1) biosynthesized of Bio-SeNPs from different sources (plant extracts, fungi and bacteria) and their antibacterial activity against various foodborne bacteria; (2) the antibacterial mechanisms of Bio-SeNPs, including penetration of cell wall, damage to cell membrane and contents leakage, inhibition of biofilm formation, and induction of oxidative stress; (3) the potential antibacterial applications of Bio-SeNPs as food packaging materials, food additives and fertilizers/feeds for crops and animals in the food industry; and (4) the cytotoxicity and animal toxicity of Bio-SeNPs. The related knowledge contributes to enhancing our understanding of Bio-SeNP applications and makes a valuable contribution to ensuring food safety.

The Developments of Surface-Functionalized Selenium Nanoparticles and Their Applications in Brain Diseases Therapy

Selenium (Se) and its organic and inorganic compounds in dietary supplements have been found to possess excellent pharmacodynamics and biological responses. However, Se in bulk form generally exhibits low bioavailability and high toxicity. To address these concerns, nanoscale selenium (SeNPs) with different forms, such as nanowires, nanorods, and nanotubes, have been synthesized, which have become increasingly popular in biomedical applications owing to their high bioavailability and bioactivity, and are widely used in oxidative stress-induced cancers, diabetes, and other diseases. However, pure SeNPs still encounter problems when applied in disease therapy because of their poor stability. The surface functionalization strategy has become increasingly popular as it sheds light to overcome these limitations in biomedical applications and further improve the biological activity of SeNPs. This review summarizes synthesis methods and surface functionalization strategies employed for the preparation of SeNPs and highlights their applications in treating brain diseases.

The accessibility, necessity, and significance of certified reference materials for total selenium content and its species to improve food laboratories' performance

Micronutrients are one of the most important groups of nutrients that our body needs daily in trace amounts to tackle deficiencies. Selenium (Se) is a mineral that occurs naturally in foods and is an essential component of selenoproteins that support the healthy functioning of the human body. Therefore, monitoring dietary Se concentrations must be a higher priority to meet daily intakes. Fulfillment can be addressed through applying various analytical techniques, and the certified reference materials (CRMs) tool plays a crucial role in quality assurance/quality control (QA/QC). The availability of certified CRMs for total Se content with addition to their species is presented. The review emphasizes the necessity of incorporating more food matrix CRMs certifying Se species, apart from total Se content, to meet method validation requirements for food analysis laboratories. This would help CRM producers bridge the gap between available food matrix materials that are not certified for Se species.

A synthetic community of siderophore-producing bacteria increases soil selenium bioavailability and plant uptake through regulation of the soil microbiome

Dietary selenium (Se) is an effective strategy to meet Se requirement of human body, and Se biofortification in crops in seleniferous soils with selenobacteria represents an eco-friendly biotechnique. In this study, we tested the effectiveness of siderophore-producing bacterial (SPB) synthetic communities (SynComs) in promoting plant Se uptake in a subtropical seleniferous soil where the fixation of Se by ferric-oxides is severe. The results indicated that SPB SynComs drastically elevated soil bioavailable Se content by up to 68.7 %, and significantly increased plant Se concentration and uptake by up to 83.1 % and 92.2 %, respectively. Seven out of ten SPB isolates in the SynComs were enriched in soils after 120 days of inoculation. Additionally, variation partitioning analysis (VPA) revealed that the contribution of soil bacterial community (up to 42.8 %) to the increased plant Se uptake was much greater than that of soil bioavailable Se (up to 5.1 %), suggesting a direct pathway other than the pathway of mobilizing Se. The relative abundances of some operational taxonomic units (OTUs) showed significantly positive relationship with plant Se status but not with soil Se status, which supports the results of VPA. Network analysis indicates that some inoculated SPB isolates promoted plant Se uptake by regulating the native bacterial taxa. Taken together, this study demonstrates that SPB can be used in Se biofortification in crops, especially in subtropical soils.

Antimicrobial activity of synthesized graphene oxide-selenium nanocomposites: A mechanistic insight

Nanoparticles have recently gained interest as an anti-bacterial agent due to their large surface area/volume ratio and potential to compromise the integrity of bacterial cell membranes. Due to its versatility and anti-bacterial activity, graphene-based materials have drawn significant interest in biomedical applications. One of the greatest threats to life in the modern technological era is the pervasiveness of infectious diseases since bacteria cells are constantly updating themselves to resist antibiotics. In this presented study, GO-Se nanocomposite has been synthesized using polymer solution via a simple dispersion method. The structural and physicochemical properties of nanocomposite were investigated in detail. Staphylococcus aureus, Proteus vulgaris, and Bacillus subtilis bacterial strains were employed to study the anti-bacterial activity of GO-Se nanocomposite. The results show that the synthesized nanocomposites have good efficacy as an anti-bacterial agent. UV-vis spectroscopy, FTIR spectroscopy, HRTEM, XPS, and Raman spectroscopy were used to analyze the as-prepared GO and GO-Se nanocomposite.

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.

Synthesis, Characterization of Low Molecular Weight Chitosan Selenium Nanoparticles and Its Effect on DSS-Induced Ulcerative Colitis in Mice

Selenium nanoparticles have attracted extensive attention due to their good bioavailability and activity. In the present study, a new form of selenium nanoparticle (Low molecular weight chitosan selenium nanoparticles (LCS-SeNPs)) were synthesized in a system of sodium selenite and acetic acid. The size, element state, morphology and elementary composition of LCS-SeNPs were characterized by using various spectroscopic and microscopic measurements. The protection of LCS-SeNPs against dextran sulfate sodium (DSS)-induced intestinal barrier dysfunction and the inherent mechanisms of this process were investigated. The results showed that LCS-SeNPs, with an average diameter of 198 nm, zero-valent and orange-red relatively uniform spherical particles were prepared. LCS-SeNPs were mainly composed of C, N, O and Se elements, of which Se accounted for 39.03% of the four elements C, N, O and Se. LCS-SeNPs reduced colon injury and inflammation symptoms and improved intestinal barrier dysfunction. LCS-SeNPs significantly reduced serum and colonic inflammatory cytokines TNF-α and IL-6 levels. Moreover, LCS-SeNPs remarkably increased antioxidant enzyme GSH-Px levels in serum and colonic tissue. Further studies on inflammatory pathways showed that LCS-SeNPs alleviated DSS-induced colitis through the NF-κB signaling pathway, and relieved inflammatory associated oxidative stress through the Nrf2 signaling pathway. Our findings suggested that LCS-SeNPs are a promising selenium species with potential applications in the treatment of oxidative stress related inflammatory intestinal diseases.

Exploring nanoselenium to tackle mutated SARS-CoV-2 for efficient COVID-19 management

Despite ongoing public health measures and increasing vaccination rates, deaths and disease severity caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its new emergent variants continue to threaten the health of people around the world. Therefore, there is an urgent need to develop novel strategies for research, diagnosis, treatment, and government policies to combat the variant strains of SARS-CoV-2. Since the state-of-the-art COVID-19 pandemic, the role of selenium in dealing with COVID-19 disease has been widely discussed due to its importance as an essential micronutrient. This review aims at providing all antiviral activities of nanoselenium (Nano-Se) ever explored using different methods in the literature. We systematically summarize the studied antiviral activities of Nano-Se required to project it as an efficient antiviral system as a function of shape, size, and synthesis method. The outcomes of this article not only introduce Nano-Se to the scientific community but also motivate scholars to adopt Nano-Se to tackle any serious virus such as mutated SARS-CoV-2 to achieve an effective antiviral activity in a desired manner.

Lentinan-functionalized selenium nanoparticles induce apoptosis and cell cycle arrest in human colon carcinoma HCT-116 cells

Selenium nanoparticles (SeNPs) have gained extensive attention for their excellent biological activity and low toxicity. However, SeNPs are extremely liable to aggregate into non-bioactive or gray elemental selenium, which limits their application in the biomedicine field. This study aimed to prepare stable SeNPs by using lentinan (LNT) as a template and evaluate its anti-colon cancer activity. The average particle diameter of obtained lentinan-selenium nanoparticles (LNT-SeNPs) was approximately 59 nm and presented zero-valent, amorphous, and spherical structures. The monodisperse SeNPs were stabilized by LNT through hydrogen bonding interactions. LNT-SeNPs solution remained highly stable at 4°C for at least 8 weeks. The stability of LNT-SeNPs solution sharply decreased under high temperature and strong acidic conditions. LNT-SeNPs showed no obvious cytotoxic effect on normal cells (IEC-6) but significantly inhibited the proliferation of five colon cancer cells (HCT-116, HT-29, Caco-2, SW620, and CT26). Among them, LNT-SeNPs exhibited the highest sensitivity toward HCT-116 cells with an IC50 value of 7.65 μM. Also, LNT-SeNPs displayed better cancer cell selectivity than sodium selenite and selenomethionine. Moreover, LNT-SeNPs promoted apoptosis of HCT-116 cells through activating mitochondria-mediated apoptotic pathway. Meanwhile, LNT-SeNPs induced cell cycle arrest at G0/G1 phase in HCT-116 cells via modulation of cell cycle regulatory proteins. The results of this study indicated that LNT-SeNPs possessed strong potential application in the treatment of colorectal cancer (CRC).

Microbial oxidation of organic and elemental selenium to selenite

Selenium (Se) is an essential trace element for life. Se reduction has attracted much attention in the microbial Se cycle, but there is less evidence for Se oxidation. In particular, it is unknown whether microorganisms oxidise organic Se(-II). In this study, four strains of bacteria, namely Dyella spp. LX-1 and LX-66, and Rhodanobacter spp. LX-99 and LX-100, isolated from seleniferous soil, were involved in the oxidation of selenomethionine (SeMet), selenocystine (SeCys2), selenourea and Se(0) to selenite (Se(IV)) in pure cultures. The oxidation rates of organic Se were more rapidly than those of Se(0) in liquid media. Then Se(0) and SeMet were used as examples, microbial oxidation was the predominant process for both additional Se(0) and SeMet in sterilised alkaline or acidic soils. The Se(IV) concentrations were significantly higher at pH 8.56 than at pH 5.25. In addition, water-soluble Se (SOLSe) and exchangeable and carbonate-bound Se (EXC-Se) fractions increased dramatically with these four Se-oxidising bacteria in unsterilised seleniferous soil. To our knowledge, this is the first study to find that various bacteria are involved in the oxidation of organic Se to Se oxyanions, bridging the gap of Se redox in the Se biogeochemical cycle.

Biogenic and facile synthesis of selenium nanoparticles using Vaccinium arctostaphylos L. fruit extract and anticancer activity against in vitro model of breast cancer

Biogenic synthesis of selenium nanoparticles (SeNPs) using plant extracts has emerged as a promising alternative approach to traditional chemical synthesis. The current study aims to introduce a safe, low-cost, and green synthesis of SeNPs using fresh fruit extract of Vaccinium arctostaphylos L. The biogenic synthesis of SeNPs was confirmed by different analyses including ultraviolet-visible spectrophotometry, Fourier transform infrared, and energy-dispersive X-ray. Also, the crystalline nature, size, and morphology of the obtained SeNPs were characterized by X-ray diffraction, dynamic light scattering, field emission scanning electron microscopy, and transmission electron microscopy techniques. The SeNPs were successfully synthesized with fruit extract of V. arctostaphylos L. in a regular spherical form and narrow size distribution with suitable zeta-potential values and exhibited appropriate biocompatibility. It revealed that the synthesized SeNPs can significantly inhibit the growth of 4T1 breast cancer cells with an IC₅₀ of ∼84.19 ± 25.96 µg/ml after 72 h treatment. Overall, it can be concluded that the green synthesized SeNPs can be attractive, nontoxic, and eco-friendly candidates for drug delivery or medicinal applications.

Dietary supplementation with biogenic selenium nanoparticles alleviate oxidative stress-induced intestinal barrier dysfunction

Selenium (Se) is an essential micronutrient that promotes body health. Endemic Se deficiency is a major nutritional challenge worldwide. The low toxicity, high bioavailability, and unique properties of biogenic Se nanoparticles (SeNPs) allow them to be used as a therapeutic drug and Se nutritional supplement. This study was conducted to investigate the regulatory effects of dietary SeNPs supplementation on the oxidative stress-induced intestinal barrier dysfunction and its association with mitochondrial function and gut microbiota in mice. The effects of dietary SeNPs on intestinal barrier function and antioxidant capacity and its correlation with gut microbiota were further evaluated by a fecal microbiota transplantation experiment. The results showed that Se deficiency caused a redox imbalance, increased the levels of pro-inflammatory cytokines, altered the composition of the gut microbiota, and impaired mitochondrial structure and function, and intestinal barrier injury. Exogenous supplementation with biogenic SeNPs effectively alleviated diquat-induced intestinal barrier dysfunction by enhancing the antioxidant capacity, inhibiting the overproduction of reactive oxygen species (ROS), preventing the impairment of mitochondrial structure and function, regulating the immune response, maintaining intestinal microbiota homeostasis by regulating nuclear factor (erythroid-derived-2)-like 2 (Nrf2)-mediated NLR family pyrin domain containing 3 (NLRP3) signaling pathway. In addition, Se deficiency resulted in a gut microbiota phenotype that is more susceptible to diquat-induced intestinal barrier dysfunction. Supranutritional SeNPs intake can optimize the gut microbiota to protect against intestinal dysfunctions. This study demonstrates that dietary supplementation of SeNPs can prevent oxidative stress-induced intestinal barrier dysfunction through its regulation of mitochondria and gut microbiota.

Citric acid-mediated green synthesis of selenium nanoparticles: antioxidant, antimicrobial, and anticoagulant potential applications

Using microwave technique in the presence of citric acid, selenium nanoparticles (SeNPs) were fabricated. The morphological characteristics revealed that the spherical SeNPs with diameters ranging from 10.5 to 20 nm aggregated spherical shapes with sizes ranging from 0.67 to 0.83 mm. Moreover, the antioxidant efficacy was assessed by the DPPH radical scavenging test, which depicted that green-prepared nanoparticle at a 106.3 mg/mL dosage had the maximum scavenging capacity (301.1 ± 11.42 mg/g). Otherwise, with nanoparticle concentrations of 500 mg/ml, in vitro cell viability of SeNPs through human breast cancer MCF-7 cell lines was reduced to 61.2 ± 2.2% after 1 day of exposure. The antibacterial activity was tested against G-negative Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli), G-positive bacteria Bacillus subtilis (B. subtilis), and Staphylococcus aureus (S. aureus), which demonstrated that SeNPs had little activity against S. aureus. Still, it had the highest activity against E. coli, with a zone of inhibition (ZOI) of 25.2 ± 1.5 mm compared to 16.0 ± 0.6 mm for the standard antibiotic. Most notably, biogenic SeNPs have anticoagulant activities using activated partial thromboplastin time (aPTT) assessment. Based on previous findings, SeNPs can be used in medical aid and their cell viability, antioxidant, anticoagulant, and effects on bacteria.

Histopathology, pharmacokinetics and estimation of interleukin-6 levels of Moringa oleifera leaves extract-functionalized selenium nanoparticles against rats induced hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most dangerous cancers in all the world. This study focused on prevention and therapy of hepatocellular carcinoma (HCC) using Moringa oleifera extract combined with vitamin C and selenium in a nanoplatform (MO/asc.-Se-NPs).

Results

Full characterization of MO/asc.-Se-NPs was performed by using different analytical techniques (TEM, DLS, zeta-sizer), and its antioxidant capacity was measured by DPPH assay. Biodistribution study was performed with the aid of radiolabeling technique using technetium-99m in normal albino mice. HCC was induced in Wister albino rats to evaluate the efficiency of MO/asc.-Se-NPs in the treatment of HCC. The biomarker analysis (ALT, AST and ALB) shows improvement in its values in prevention and treated groups by using MO/asc.-Se NP. The levels of inflammatory marker interleukin 6 (IL6 tissue homogenate) was improved by decreasing its values in these two groups also. Histology section of tissue liver showed alleviation in treated and prevention groups.

Conclusions

In conclusion, MO/asc.-Se-NPs can be used as a potential agent for prevention and treatment of HCC after further preclinical studies.

IAEA Contribution to Nanosized Targeted Radiopharmaceuticals for Drug Delivery

The rapidly growing interest in the application of nanoscience in the future design of radiopharmaceuticals and the development of nanosized radiopharmaceuticals in the late 2000′s, resulted in the creation of a Coordinated Research Project (CRP) by the International Atomic Energy Agency (IAEA) in 2014. This CRP entitled ‘Nanosized delivery systems for radiopharmaceuticals’ involved a team of expert scientist from various member states. This team of scientists worked on a number of cutting-edge areas of nanoscience with a focus on developing well-defined, highly effective and site-specific delivery systems of radiopharmaceuticals. Specifically, focus areas of various teams of scientists comprised of the development of nanoparticles (NPs) based on metals, polymers, and gels, and their conjugation/encapsulation or decoration with various tumor avid ligands such as peptides, folates, and small molecule phytochemicals. The research and development efforts also comprised of developing optimum radiolabeling methods of various nano vectors using diagnostic and therapeutic radionuclides including Tc-99m, Ga-68, Lu-177 and Au-198. Concerted efforts of teams of scientists within this CRP has resulted in the development of various protocols and guidelines on delivery systems of nanoradiopharmaceuticals, training of numerous graduate students/post-doctoral fellows and publications in peer reviewed journals while establishing numerous productive scientific networks in various participating member states. Some of the innovative nanoconstructs were chosen for further preclinical applications—all aimed at ultimate clinical translation for treating human cancer patients. This review article summarizes outcomes of this major international scientific endeavor.

Emerging Theranostic Nanomaterials in Diabetes and Its Complications

Diabetes mellitus (DM) refers to a group of metabolic disorders that are characterized by hyperglycemia. Oral subcutaneously administered antidiabetic drugs such as insulin, glipalamide, and metformin can temporarily balance blood sugar levels, however, long-term administration of these therapies is associated with undesirable side effects on the kidney and liver. In addition, due to overproduction of reactive oxygen species and hyperglycemia-induced macrovascular system damage, diabetics have an increased risk of complications. Fortunately, recent advances in nanomaterials have provided new opportunities for diabetes therapy and diagnosis. This review provides a panoramic overview of the current nanomaterials for the detection of diabetic biomarkers and diabetes treatment. Apart from diabetic sensing mechanisms and antidiabetic activities, the applications of these bioengineered nanoparticles for preventing several diabetic complications are elucidated. This review provides an overall perspective in this field, including current challenges and future trends, which may be helpful in informing the development of novel nanomaterials with new functions and properties for diabetes diagnosis and therapy.

Comparison of Selenium Nanoparticles and Sodium Selenite on the Alleviation of Early Atherosclerosis by Inhibiting Endothelial Dysfunction and Inflammation in Apolipoprotein E-Deficient Mice

Atherosclerosis and related cardiovascular diseases represent the greatest threats to human health, worldwide. Previous animal studies showed that selenium nanoparticles (SeNPs) and Na₂SeO₃ might have anti-atherosclerotic activity, but the underlying mechanisms are poorly elucidated. This study compared the anti-atherosclerotic activity of SeNPs stabilized with chitosan (CS-SeNPs) and Na₂SeO₃ and the related mechanism in a high-fat-diet-fed apolipoprotein E-deficient mouse model of atherosclerosis. The results showed that oral administration of both CS-SeNPs and Na₂SeO₃ (40 μg Se/kg/day) for 10 weeks significantly reduced atherosclerotic lesions in mouse aortae. Mechanistically, CS-SeNPs and Na₂SeO₃ not only alleviated vascular endothelial dysfunction, as evidenced by the increase of serum nitric oxide level and the decrease of aortic adhesion molecule expression, but also vascular inflammation, as evidenced by the decrease of macrophage recruitment as well as the expression of proinflammatory molecules. Importantly, these results were replicated within in-vivo experiments on the cultured human endothelial cell line EA.hy926. Overall, CS-SeNPs had a comparable effect with Na₂SeO₃ but might have more potential in atherosclerosis prevention due to its lower toxicity. Together, these results provide more insights into the mechanisms of selenium against atherosclerosis and further highlight the potential of selenium supplementation as a therapeutic strategy for atherosclerosis.

Hepatoprotective, antioxidant and anti-inflammatory potentials of Vit-E/C@SeNPs in rats: Synthesis, characterization, biochemical, radio-biodistribution, molecular and histopathological studies

This study aimed to synthesize a nano-structure between selenium, Vit. C, and Vit. E (Vit-E/C@SeNPs) as a promising protective and therapeutic agent for hepatocellular carcinoma. Vit-E/C@SeNPs were characterized using TEM and DLS and its zetapotential was measured to evaluate its stability. DPPH assay and SRB test were performed to estimate its antioxidant capacity and cytotoxicity, respectively. A radiosynthesis of ^99mTc-Vit-E/C@SeNPs was done for further in-vivo pharmacokinetic studies on normal and solid tumor induced mice. Further, in-vivo studies were conducted to investigate Vit-E/C@SeNPs efficacy against hepatocellular damage in Wistar albino rats induced by diethylnitrosamine (DEN) / Carbon Tetra chloride (CCl₄). The synthesis results showed spherical Vit-E/C@SeNPs with core size of 50 nm, radical scavenging activity (%RSC) of 75.9%, and IC₅₀ of 27.9 µg/ml. The biochemical analysis results showed that the lower liver function biomarker values (ALT, AST, ALP, total bilirubin and GGT) has gone for the Vit-E/C@SeNPs prevention and treated group, which also showed significant depletion of liver tissue l-MDA, and obvious increase in GSH concentration and CAT activity and marked improvement in the histological feature of liver tissue. Additionally, a significant up-regulation of mRNA gene expression levels of inflammatory gene (TGFβ1, NFκB, iNOS, PPAR-γ and TNFα) and Apoptotic gene (P53) were determined by using Quantitative real-time PCR (qPCR). The values down regulate and tend to normal in prevention and control group. All of these introduce Vit-E/C@SeNPs as a promising agent as protective and therapeutic agent against DEN/ CCl₄-induced hepatocellular damage (Hepatocellular carcinoma).

Anticancer Activity of Selenium Nanoparticles In Vitro Studies

Health systems worldwide consider cancer a disease that causes the highest number of deaths per year. The low efficacy of current cancer therapies has led other areas of science to search for new alternatives, including nanomaterial sciences. Selenium nanoparticles have anticancer activity, as revealed by in vitro tests performed on prostate, breast, cervical, lung, colorectal, and liver cancer cell lines. Studies attribute anticancer activity to the anti-metastatic effect due to the inhibition of migration and invasion processes. The antiproliferative effect is the low expression of molecules such as cyclin D1, cyclin E, and CDK2. In addition to the activation of cell apoptosis by caspase-dependent mechanisms, there is a low expression of anti-apoptotic proteins such as Bcl-2 and a high expression of the apoptotic proteins like Bax and Bad. Other studies attribute anticancer activity to the activation of cell necroptosis, where molecules such as TNF and IRF1 participate. The pharmacological potential of selenium nanoparticles depends primarily on the administered dose, particle size, and chemical composition. Furthermore, several studies have shown that the administration of these nanoparticles is safe due to their low toxicity in non-cancerous cells. In this review, the most relevant antecedents on the anticancer potential of selenium nanoparticles in prostate, breast, cervical, lung, liver, and colorectal cancer cell lines are discussed.

Detection of Oxidative Stress Induced by Nanomaterials in Cells-The Roles of Reactive Oxygen Species and Glutathione

The potential of nanomaterials use is huge, especially in fields such as medicine or industry. Due to widespread use of nanomaterials, their cytotoxicity and involvement in cellular pathways ought to be evaluated in detail. Nanomaterials can induce the production of a number of substances in cells, including reactive oxygen species (ROS), participating in physiological and pathological cellular processes. These highly reactive substances include: superoxide, singlet oxygen, hydroxyl radical, and hydrogen peroxide. For overall assessment, there are a number of fluorescent probes in particular that are very specific and selective for given ROS. In addition, due to the involvement of ROS in a number of cellular signaling pathways, understanding the principle of ROS production induced by nanomaterials is very important. For defense, the cells have a number of reparative and especially antioxidant mechanisms. One of the most potent antioxidants is a tripeptide glutathione. Thus, the glutathione depletion can be a characteristic manifestation of harmful effects caused by the prooxidative-acting of nanomaterials in cells. For these reasons, here we would like to provide a review on the current knowledge of ROS-mediated cellular nanotoxicity manifesting as glutathione depletion, including an overview of approaches for the detection of ROS levels in cells.

Long-term administration of low-dose selenium nanoparticles with different sizes aggravated atherosclerotic lesions and exhibited toxicity in apolipoprotein E-deficient mice

Exploration of long-term in vivo effects of nanomaterials, particularly those with potential biomedical applications, is quite important for better understanding and evaluating their biosafety. Selenium nanoparticles (SeNPs) has been considered as a good candidate in biomedical applications due to its high bioavailability, considerable biological activity, and low toxicity. However, its long-term biological effects and biosafety remain unknown. Our previous study demonstrated that 8-week supplementation with SeNPs (50 μg Se/kg/day) was safe and had an anti-atherosclerotic activity in apolipoprotein E-deficient (ApoE^-/-) mice, a well-known animal model of atherosclerosis. As a chronic disease, atherosclerosis needs long-term drug therapy. The aim of this study is to investigate the long-term effects of SeNPs with different sizes on atherosclerotic lesions and their biosafety in ApoE^-/- mice fed with a high fat diet. Unexpectedly, the results showed that 24-week administration of SeNPs even at a low dose (50 μg Se/kg/day) aggravated atherosclerotic lesions. Furthermore, SeNPs exacerbated oxidative stress by inhibiting the activities of antioxidant enzymes and the expression of antioxidant selenoenzymes. SeNPs also exacerbated hyperlipidaemia by inducing hepatic lipid metabolic disorder. In the meanwhile, SeNPs aggravated organ injury, especially liver and kidney injury. The above adverse effects of SeNPs were size dependent: SeNPs with the size of 40.4 nm showed the highest adverse effects among the SeNPs with three sizes (23.1 nm, 40.4 nm, and 86.8 nm). In conclusion, the present work shows that long-term administration of low-dose SeNPs aggravated atherosclerotic lesions by enhancing oxidative stress and hyperlipidaemia in ApoE^-/- mice, indicative of cardiovascular toxicity. Moreover, long-term administration of SeNPs led to injury to liver and kidney. These results offer novel insights for better understanding the biosafety of SeNPs and other biomedical nanomaterials.

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.

Selenium nanoparticles inhibit the formation of atherosclerosis in apolipoprotein E deficient mice by alleviating hyperlipidemia and oxidative stress

Atherosclerosis can cause severe cardiovascular diseases, which is the most common cause of death in the world. It's of great significance to study the prevention and treatment of atherosclerosis. Selenium nanoparticles (SeNPs) has drawn more and more attention due to high biological activity, high bioavailability, strong antioxidant capacity and low toxicity, exhibiting great potential in biomedical application. Thus, this study aimed at explore the anti-atherosclerotic effect of two kinds of SeNPs, bovine serum albumin (BSA) surface-decorated SeNPs and chitosan (CS) surface-decorated SeNPs (CS-SeNPs), in apolipoprotein E deficient (ApoE-/-) mice fed with a high-cholesterol and high-fat diet, and the possible mechanisms. The results demonstrated that both BSA-SeNPs (25, 50 and 100 μg Se/kg body weight/day) and CS-SeNPs (50 μg Se/kg body weight/day) could reduce atherosclerotic lesions in ApoE-/- mice after oral administration for 12 weeks. And these effects might mainly attributed to the ability of BSA-SeNPs and CS-SeNPs to inhibit hyperlipidemia by suppressing hepatic cholesterol and fatty acid metabolism, and alleviate oxidative stress by enhancing antioxidant activity. Moreover, the benefits of BSA-SeNPs were dose-dependent and the medium dose of BSA-SeNPs (50 μg Se/kg body weight/day) was optimal. Generally, BSA-SeNPs with mean size 38.5 nm and negative surface charge showed better anti-atherosclerotic effect than CS-SeNPs with mean size 65.8 nm and positive surface charge. These results suggested that SeNPs could significantly alleviate the formation of atherosclerosis in ApoE-/- mice, possibly by inhibiting hyperlipidemia and oxidative stress, exhibiting a potential to serve as an anti-atherosclerotic agent.

Progress and recent trends in the direct selenocyanation of (hetero)aromatic C-H bonds

This review covers recent advances in the direct selenocyanation of (hetero)aromatic C-H bonds with an emphasis on the reaction mechanisms. This novel approach is an effective means of preparing a variety of aromatic and heteroaromatic selenocyanates, which are extremely versatile synthetic precursors of selenium-containing compounds, such as selenols, seleninic acids, selenides, diselenides, and trifluoromethyl selenides.

Green Synthesis of Selenium Nanoparticles by Cyanobacterium Spirulina platensis (abdf2224): Cultivation Condition Quality Controls

Selenium nanoparticles (SeNPs) are well-known bioactive compounds. Various chemical and biological methods have been applied to SeNP synthesis. Spirulina platensis is a widely used blue-green microalgae in various industries. In this study, the biosynthesis of SeNPs using sodium selenite and Spirulina platens has been developed. The SeNP synthesis was performed at different cultivation condition including pH and illumination schedule variation. The SeNPs were characterized by FT-IR, XRD, size, and zeta potential measurements, and the antioxidant activities of selected SeNPs were evaluated by DPPH and FRAP assays. FT-IR analysis showed the production of SeNPs. The 12 h dark/12 h light cycles and continuous light exposure at pH 5 led to the production of stable SeNPs with sizes of 145 ± 6 and 171 ± 13 nm, respectively. Antioxidant activity of selected SeNPs was higher than sodium selenite. It seems that green synthesis is a safe method to produce SeNPs as well as a convenient method to scale-up this production.