Extracellular synthesis of nanoselenium from fresh water bacteria Bacillus sp., and its validation of antibacterial and cytotoxic potential

Selenium Nanoparticles as Neuroprotective Agents: Insights into Molecular Mechanisms for Parkinson's Disease Treatment

Oxidative stress and the accumulation of misfolded proteins in the brain are the main causes of Parkinson's disease (PD). Several nanoparticles have been used as therapeutics for PD. Despite their therapeutic potential, these nanoparticles induce multiple stresses upon entry. Selenium (Se), an essential nutrient in the human body, helps in DNA formation, stress control, and cell protection from damage and infections. It can also regulate thyroid hormone metabolism, reduce brain damage, boost immunity, and promote reproductive health. Selenium nanoparticles (Se-NPs), a bioactive substance, have been employed as treatments in several disciplines, particularly as antioxidants. Se-NP, whether functionalized or not, can protect mitochondria by enhancing levels of reactive oxygen species (ROS) scavenging enzymes in the brain. They can also promote dopamine synthesis. By inhibiting the aggregation of tau, α-synuclein, and/or Aβ, they can reduce the cellular toxicities. The ability of the blood-brain barrier to absorb Se-NPs which maintain a healthy microenvironment is essential for brain homeostasis. This review focuses on stress-induced neurodegeneration and its critical control using Se-NP. Due to its ability to inhibit cellular stress and the pathophysiologies of PD, Se-NP is a promising neuroprotector with its anti-inflammatory, non-toxic, and antimicrobial properties.

In vitro assessment of the effect of magnetic fields on efficacy of biosynthesized selenium nanoparticles by Alborzia kermanshahica

Cyanobacteria represent a rich resource of a wide array of unique bioactive compounds that are proving to be potent sources of anticancer drugs. Selenium nanoparticles (SeNPs) have shown an increasing potential as major therapeutic platforms and led to the production of higher levels of ROS that can present desirable anticancer properties. Chitosan-SeNPs have also presented antitumor properties against hepatic cancer cell lines, especially the Cht-NP (Chitosan-NPs), promoting ROS generation and mitochondria dysfunction. It is proposed that magnetic fields can add new dimensions to nanoparticle applications. Hence, in this study, the biosynthesis of SeNPs using Alborzia kermanshahica and chitosan (CS) as stabilizers has been developed. The SeNPs synthesis was performed at different cyanobacterial cultivation conditions, including control (without magnetic field) and magnetic fields of 30 mT and 60 mT. The SeNPs were characterized by uv-visible spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), Dynamic light scattering (DLS), zeta potential, and TEM. In addition, the antibacterial activity, inhibition of bacterial growth, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC), as well as the antifungal activity and cytotoxicity of SeNPs, were performed. The results of uv-visible spectrometry, DLS, and zeta potential showed that 60 mT had the highest value regarding the adsorption, size, and stabilization in compared to the control. FTIR spectroscopy results showed consistent spectra, but the increased intensity of peaks indicates an increase in bond number after exposure to 30 mT and 60 mT. The results of the antibacterial activity and the inhibition zone diameter of synthesized nanoparticles showed that Staphylococcus aureus was more sensitive to nanoparticles produced under 60 mT. Se-NPs produced by Alborzia kermanshahica cultured under a 60 mT magnetic field exhibit potent antimicrobial and anticancer properties, making them a promising natural agent for use in the pharmaceutical and biomedical industries.

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.

Biogenic selenium nanoparticles: trace element with promising anti-toxoplasma effect

Toxoplasmosis is an opportunistic infection caused by the coccidian Toxoplasma gondii which represents a food and water contaminant. The available chemotherapeutic agents for toxoplasmosis are limited and the choice is difficult when considering the side effects. Selenium is an essential trace element. It is naturally found in dietary sources, especially seafood, and cereals. Selenium and selenocompounds showed anti-parasitic effects through antioxidant, immunomodulatory, and anti-inflammatory mechanisms. The present study evaluated the potential efficacy of environmentally benign selenium nanoparticles (SeNPs) against acute toxoplasmosis in a mouse model. SeNPs were fabricated by nanobiofactory Streptomyces fulvissimus and characterized by different analytical techniques including, UV-spectrophotometry, transmission electron microscopy, EDX, and XRD. Swiss albino mice were infected with Toxoplasma RH strain in a dose of 3500 tachyzoites in 100 μl saline to induce acute toxoplasmosis. Mice were divided into five groups. Group I: non-infected, non-treated, group II: infected, non-treated, group III: non-infected, treated with SeNPs, group IV: infected, treated with co-trimoxazole (sulfamethoxazole/trimethoprim) and group V: infected, treated with SeNPs. There was a significant increase in survival time in the SeNPs-treated group and minimum parasite count was observed compared to untreated mice in hepatic and splenic impression smears. Scanning electron microscopy showed tachyzoites deformity with multiple depressions and protrusions, while transmission electron microscopy showed excessive vacuolization and lysis of the cytoplasm, especially in the area around the nucleus and the apical complex, together with irregular cell boundary and poorly demarcated cell organelles. The present study demonstrated that the biologically synthesized SeNPs can be a potential natural anti-Toxoplasma agent in vivo.

Biological Activities of Selenium Nanoparticles Synthesized from Camellia sinensis (L) Kuntze Leaves

Selenium in the form of selenoproteins is formed through a unique translocation recoding pathway and plays a vital role in human metabolism. Selenium nanoparticles (SeNPs) when synthesized using green synthesis from plant extract offer more advantages than physical and chemical methods. Previous studies have synthesized selenium nanoparticles from green tea and white tea; here, we report the synthesis of selenium nanoparticles from Camillia sinensis (L) Kuntze leaves (black tea) by green synthesis. Moreover, we have tested the antimicrobial and antioxidant activity of the plant extract, SeNPs, and combination of plant extract and SeNPs which have not been previously studied. The antimicrobial efficacy of SeNPs was tested against Klebsiella pneumonia, Candida albicans, and Staphylococcus aureus. They showed inhibitory effects against these organisms individually and in combination with Camellia sinensis leaf extract. The antioxidant properties of SeNPs were checked using FRAP and DPPH assays, where high radical scavenging activity was exhibited by SeNPs and in combination with the plant extract. Furthermore, synthesized SeNPs were examined for cytotoxicity tolerance against Vero cells and their IC50 values determine that plant-mediated SeNPs showed high cytotoxicity at minimal concentrations. If explored further, the reducing, capping, and stabilizing capabilities of SeNPs may demonstrate other inhibitory effects and could be explored for understanding the role of selenium in cellular metabolism.

Antifungal screening of selenium nanoparticles biosynthesized by microcystin-producing Desmonostoc alborizicum

Metal nanoparticles exhibit excellent antifungal abilities and are seen as a good substitute for controlling different kinds of fungi. Of all known taxa, cyanobacteria have received significant consideration as nanobiofactories, as a result of the cellular assimilation of heavy metals from the environment. The cellular bioactive enzymes, polysaccharides and pigments can be used as reducers and coatings during biosynthesis. The probability of the antifungal activity of selenium nanoparticles (SeNPs) to prevent plant fungi that can affect humans was evaluated and a toxic Iranian cyanobacterial strain of Desmonostoc alborizicum was used to study the biotechnology of SeNP synthesis for the first time. Characterization of nanoparticles with a UV-Vis spectrophotometer showed the formation of SeNPs in the range of 271-275 nm with the appearance of an orange color. Morphological examination of nanoparticles with Transmission Electron Microscopy (TEM), revealed the spherical shape of nanoparticles. The results of X-Ray Diffraction (XRD) showed 7 peaks and a hexagonal structure of average crystal size equal to 58.8 nm. The dispersion index of SeNPs was reported as 0.635, which indicated the homogeneity of the nanoparticle droplet size. The zeta potential of the nanoparticles was + 22.7. Fourier-transform infrared spectroscopy (FTIR) analysis exhibited a sharp and intense peak located at the wave number of 404 cm- 1, related to the SeNPs synthesized in this research. The results of the antifungal activity of SeNPs showed among the investigated fungi, Pythium ultimum had the highest resistance to SeNPs (14.66 ± 0.52 µg/ml), while Alternaria alternata showed the highest sensitivity (9.66 ± 0.51 µg/ml) (p < 0.05). To the best of our knowledge this is the first report concerning the characterization and antifungal screening of SeNPs biosynthesized by Iranian cyanobacteria, which could be used as effective candidates in medical applications.

Anticancer activity of lactoferrin-coated biosynthesized selenium nanoparticles for combating different human cancer cells via mediating apoptotic effects

The present study aims to develop a novel nanocombination with high selectivity against several invasive cancer cells, sparing normal cells and tissues. Bovine lactoferrin (bLF) has recently captured the interest of numerous medical fields owing to its biological activities and well-known immunomodulatory effects. BLF is an ideal protein to be encapsulated or adsorbed into selenium nanocomposites (Se NPs) in order to produce stable nanocombinations with potent anticancer effects and improved immunological functions. The biosynthesis of the functionalized Se NPs was achieved using Rhodotorula sp. strain MZ312359 via a simultaneous bio-reduction approach to selenium sodium salts. The physicochemical properties of Se NPs using SEM, TEM, FTIR, UV Vis, XRD, and EDX confirmed the formation of uniform agglomerated spheres with a size of 18-40 nm. Se NPs were successfully embedded in apo-LF (ALF), forming a novel nanocombination of ALF-Se NPs with a spherical shape and an average nanosize of less than 200 nm. The developed ALF-Se NPs significantly displayed an effective anti-proliferation efficiency against many cancer cells, including MCF-7, HepG-2, and Caco-2 cell lines, as compared to Se NPs and ALF in free forms. ALF-Se NPs showed a significant selectivity impact (> 64) against all treated cancer cells at IC₅₀ 63.10 ≤ μg/mL, as well as the strongest upregulation of p53 and suppression of Bcl-2, MMP-9, and VEGF genes. Besides, ALF-Se NPs were able to show the maximum activation of transcrition of key redox mediator (Nrf2) with suppression in reactive oxygen species (ROS) levels inside all treated cancer cells. This study demonstrates that this novel nanocombination of ALF-Se NPs has superior selectivity and apoptosis-mediating anticancer activity over free ALF or individual form of Se NPs.

Effect of biosynthesized selenium nanoparticles using Nepeta extract against multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii

The problems of drug resistance in bacteria have become one of the daily challenges of the clinical treatment of patients, which inevitably forces us to use agents other than common antibiotics. Among these, we can take help from different properties and applications of nanoparticles (NPs). In this work, we evaluate the antibacterial activity of biosynthesized selenium nanoparticles (SeNPs) against standard strains of multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii. The production of biosynthesized SeNPs was proved by ultraviolet-visible, Fourier transform infrared, X-ray diffractometer, Field Emission Scanning Electron Microscopy, Dynamic light scattering, and Zeta potential methods. The cytotoxicity effect of SeNPs was investigated by MTT assay. Disk diffusion agar (DDA) and minimum inhibitory concentration (MIC) tests were performed on the mentioned bacteria using different classes of standard antibiotics and SeNPs separately. The impact of SeNPs combined with the desired antibiotics for better treatment of these infections was evaluated by checkerboard assay to determine the synergism effect. After the confirmation results based on the biosynthesis of SeNPs, both standard bacterial strains were susceptible to SeNPs and had a zone of inhibition using the DDA test. Also, the results of MICs showed that biosynthesized SeNPs in lower concentrations than antibiotics cause no growth of bacteria. On the other hand, according to the checkerboard assay, SeNPs had a synergistic effect with conventional antibiotics. The antibacterial sensitivity tests demonstrated the inhibition of bacterial growth in the presence of lower concentrations of SeNPs than common antibiotics. This property can be exerted in future applications to solve the drug resistance obstacle of microorganisms in bacterial diseases.

Green synthesis of selenium nanoparticles using Rosmarinus officinalis and investigated their antimicrobial activity

The interest of many has been attracted by plant-mediated synthesizing procedures for nanoparticles since they provide certain qualities including being cost-effective, quick, and compatible with the environment. In this regard, this work introduces the production of selenium-nanoparticles (Se-NPs) in a biological manner utilizing aqueous extracts of Rosmarinus officinalis (R. officinalis). Production of Se-NPs was confirmed using UV-visible (UV-Vis) spectrophotometry. Also, dynamic light scattering (DLS) analysis was used for determination particle size distribution, while we distinguished the identification of crystalline construction of nanoparticles through the means of X-ray diffraction (XRD) pattern, DLS, and transmission electron microscopy (TEM) examination indicated that Se-NPs are often spherical with a size about 20 to 40 nm. The minimum inhibitory concentration (MIC) of the synthesized Se-NPs by R. officinalis extract against Mycobacterium tuberculosis (M. tuberculosis), Staphylococcus aureus (S. aureus), Streptococcus mutans (S. mutans), Escherichia coli (E. coli), and Pseudomonas aeruginosa (P. aeruginosa) was 256, 16, 32, 128, and 64 µg/mL, respectively. The synthesized Se-NPs had no significant effect on Mycobacterium simiae (M. simiae) and had exhibited a strong antimicrobial functionality towards the gram-positive and gram-negative bacteria and can stand as a potent antibacterial agent.

Selenite bioreduction and biosynthesis of selenium nanoparticles by Bacillus paramycoides SP3 isolated from coal mine overburden leachate

A native strain of Bacillus paramycoides isolated from the leachate of coal mine overburden rocks was investigated for its potential to produce selenium nanoparticles (SeNPs) by biogenic reduction of selenite, one of the most toxic forms of selenium. 16S rDNA sequencing was used to identify the bacterial strain (SP3). The SeNPs were characterized using spectroscopic (UV-Vis absorbance, dynamic light scattering, X-ray diffraction, and Raman), surface charge measurement (zeta potential), and ultramicroscopic (FESEM, EDX, FETEM) analyses. SP3 exhibited extremely high selenite tolerance (1000 mM) and reduced 10 mM selenite under 72 h to produce spherical monodisperse SeNPs with an average size of 149.1 ± 29 nm. FTIR analyses indicated exopolysaccharides coating the surface of SeNPs, which imparted a charge of -29.9 mV (zeta potential). The XRD and Raman spectra revealed the SeNPs to be amorphous. Furthermore, biochemical assays and microscopic studies suggest that selenite was reduced by membrane reductases. This study reports, for the first time, the reduction of selenite and biosynthesis of SeNPs by B. paramycoides, a recently discovered bacterium. The results suggest that B. paramycoides SP3 could be exploited for eco-friendly removal of selenite from contaminated sites with the concomitant biosynthesis of SeNPs.

Antimicrobial Activity of Se-Nanoparticles from Bacterial Biotransformation

Selenium nanoparticles (SeNPs) are gaining importance in the food and medical fields due to their antibacterial properties. The microbial inhibition of these kinds of particles has been tested in a wide range of Gram (+) and Gram (−) pathogenic bacteria. When SeNPs are synthesized by biological methods, they are called biogenic SeNPs, which have a negative charge caused by their interaction between surface and capping layer (bioorganic material), producing their high stability. This review is focused on SeNPs synthesis by bacteria and summarizes the main factors that influence their main characteristics: shape, size and surface charge, considering the bacteria growth conditions for their synthesis. The different mechanisms of antimicrobial activity are revised, and this review describes several biosynthesis hypotheses that have been proposed due to the fact that the biological mechanism of SeNP synthesis is not fully known.

Biosynthesized selenium nanoparticles: characterization, antimicrobial, and antibiofilm activity against Enterococcus faecalis

Background

Control over microbial growth is a crucial factor in determining the success of endodontic therapy. Enterococcus faecalis is the most resistant biofilm-forming species leading to endodontic failure. Hence, the current researches are directed towards discovering materials with superior disinfection properties and lesser cytotoxicity. This study aimed to synthesize and characterize biogenically produced Selenium Nanoparticles, and to evaluate the antimicrobial and antibiofilm efficacy, against Enterococcus Faecalis, for the following test groups: Group I: Distilled water (control), Group II: SeNPs (1 mg/ml), Group III: Calcium hydroxide (1 mg/ml), Group IV: 2% Chlorhexidine gluconate (CHX), Group V: 5.25% Sodium hypochlorite (NaOCl).

Materials and Methods

Selenium nanoparticles were derived using fresh guava leaves (Psidium guajava) and were characterized. The antibacterial efficacy against E. faecalis was evaluated by agar well diffusion method. The antibiofilm efficacy of the test groups was observed by viable cell count, antibiofilm assay, and Anthrone and Bradford’s tests. The morphology of the biofilms was analysed using the Scanning Electron Microscope and Fourier Transform Infrared spectroscopy.

Results

Antibacterial and antibiofilm efficacy of all tested solutions showed superior antibacterial and antibiofilm efficacy when compared to the control group. Overall, SeNPs (Group II) was the most effective against E. faecalis biofilm, followed by NaOCl (Group V), CHX (Group IV), and Ca(OH)₂ (Group III).

Conclusion

Biogenically produced SeNPs emerged as a novel antibacterial and antibiofilm agent against E. faecalis. This nano-formulation demonstrates the potential to be developed as a root canal disinfectant combating bacterial biofilm in endodontics after the results have been clinically extrapolated.

Biogenic Nanoparticles: Synthesis, Characterisation and Applications

Nanotechnology plays a big part in our modern daily lives, ranging from the biomedical sector to the energy sector. There are different physicochemical and biological methods to synthesise nanoparticles towards multiple applications. Biogenic production of nanoparticles through the utilisation of microorganisms provides great advantages over other techniques and is increasingly being explored. This review examines the process of the biogenic synthesis of nanoparticles mediated by microorganisms such as bacteria, fungi and algae, and their applications. Microorganisms offer a disparate environment for nanoparticle synthesis. Optimum production and minimum time to obtain the desired size and shape, to improve the stability of nanoparticles and to optimise specific microorganisms for specific applications are the challenges to address, however. Numerous applications of biogenic nanoparticles in medicine, environment, drug delivery and biochemical sensors are discussed.