Synthesis Of Selenium Nanoparticles Research Articles

Reducing agents influence the shapes of selenium nanoparticles (SeNPs) and subsequently their antibacterial and antioxidant activity

Selenium is an important element which is required in trace amounts for maintaining proper health in humans. There are various reports available on the biomedical properties of selenium such as anticancer, antibacterial and antioxidant activities. It has been shown that by controlling shape of the nanoparticles their properties can be tailored. A simple method for controlling the shape of Selenium nanoparticles (SeNPs) is proposed in the current study. SeNPs of various shapes such as rods, spheres and cubes has been obtained by using reducing agents such as BSA (Bovine serum albumin), D-Glucose and Soluble starch (amylum) respectively. The obtained particles were characterized by FTIR (Fourier-transform infrared spectroscopy), UV-Visible spectroscopy, SEM (Scanning electron microscopy) and EDX (Energy dispersive X-ray analysis). FTIR analysis showed the presence of functional groups responsible for the synthesis of SeNPs. UV-Visible spectroscopy revealed the formation of SeNPs uniformly in 200–300 nm regions. SEM-EDX results further confirmed the presence of SeNPs in nano-suspensions. The SeNPs synthesized using soluble starch exhibited considerably higher antioxidant activity. Antimicrobial assays done against Bacillus subtilis implied a very high antibacterial activity of synthesized SeNPs.

Selenium nanoparticles: synthesis, characterization and study of their cytotoxicity, antioxidant and antibacterial activity

This report concerns the green synthesis of selenium nanoparticles (Se-NPs) through chemical reduction method using ascorbic acid (Vitamin C) as a reluctant and polyvinyl alcohol (PVA) or chitosan (CS) as stabilizers. Ultraviolet-visible (UV–vis) absorption spectroscopy, dynamic light scattering (DLS), fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) were applied as the main characterization tools. The cytotoxicity of Se-NPs on fibroblast L929 cells was determined by MTT assay. The nanoparticles showed low toxicity toward the investigated cell line which remained more than 50% viable at 170 ppm for 24 h. The in-vitro antioxidant property of the synthesized Se nanoparticles was evaluated by radical scavenging (DPPH) assay. The IC50 values of the nanoparticles were 26.56 and 530 ppm for PVA coated SeNPs (PVA-SeNPs) and CS coated SeNPs (CS–SeNPs), respectively. Finally, the antibacterial activity of Se-NPs was determined on the gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, and the gram positive bacteria Staphylococcus aureus, Streptococcus epidermidis. The results showed that Se nanoparticles exhibited dose-dependent antibacterial activity against all the four bacterial strains tested. Noticeably, PVA-SeNPs exhibited significant effect against S. epidermidis (MIC 125 ppm) and S. aureus (MIC 125 ppm). The results of this study indicate that Se nanoparticles can be potentially used as antimicrobial and antioxidant agents.

Highly Uniform Synthesis of Selenium Nanoparticles with EGFR Targeting and Tumor Microenvironment-Responsive Ability for Simultaneous Diagnosis and Therapy of Nasopharyngeal Carcinoma.

Rational design of multifunctional and smart drug-delivered nanoplatforms is a promising strategy to achieve simultaneous diagnosis, real-time monitoring, and therapy of cancers. Herein, highly uniform and stable selenium nanoparticles with epidermal growth factor receptor (EGFR) targeting and tumor microenvironment-responsive ability (Se-5Fu-Gd-P(Cet/YI-12)) were designed and synthesized by using EGFR as the targeting molecule, gadolinium chelate as the magnetic resonance imaging contrast agent, 5-fluorouracil (5Fu) and cetuximab as drug payloads, polyamidoamine (PAMAM) and 3,3'-dithiobis (sulfosuccinimidyl propionate) as the response agents of intratumoral glutathione, and pH for the treatment and diagnosis of nasopharyngeal carcinoma (NPC). This Se nanoplatform showed excellent magnetic resonance imaging capability and has the potential for its clinical application as a diagnostic agent for tumor tissue specimens. Additionally, in vitro cellular experiments showed that by means of introducing clinical targeted drugs and peptides not only validly increased the intracellular uptake of the Se nanoplatform in NPC cells but also enhanced its penetration ability toward CNE tumor spheroids, resulting in simultaneous inhibition of CNE cell growth, invasion, and migration. In addition, the sequentially triggered bioresponsive property of the nanoplatform in a tumor microenvironment effectively improved the targeting delivery and anticancer efficiency of payloads. Overall, this study not only provides a strategy for facile synthesis of highly uniform and stable nanomedicines and tailing of the bioresponsive property but also sheds light on its application in targeting theranosis of NPC.

Aloe vera leaf extract mediated green synthesis of selenium nanoparticles and assessment of their In vitro antimicrobial activity against spoilage fungi and pathogenic bacteria strains

AbstractSelenium as an essential trace element for the health of the humans was used to hydrothermally synthesis of selenium nanoparticle (Se NPs) usingAloe veraleaf extract (ALE). Effects of synthesis parameters namely; amount of ALE (1–5 ml) and amount of Na2SeO3solution (10–30 ml), on the particle size and colour intensity of the solution containing Se NPs were studied using response surface methodology. FT-IR spectroscopy, UV-Vis spectrophotometry, DLS analyzer and TEM were used to determine the specifications of the ALE and synthesized Se NPs. Obtained results indicated that the ALE contained several bioactive compounds, which they had hydroxyl and amide І groups in their structures and these two functional groups had key roles in the reduction of the selenium ions to form Se NPs and stabilizing of them. Furthermore, spherical fabricated Se NPs using obtained optimum synthesis parameters, 4.92 mL of ALE and 13.03 mL of Na2SeO3solution, had colour intensity, mean particle size, zeta potential and polydispersity index values of 3.0% a.u., 50 nm, -18 mV and 0.344, respectively according to the DLS analysis. The synthesized Se NPs had also high antibacterial and antifungal activities against 4 selected pathogenic bacteria and spoilage fungi strains.

Efficacy of Biogenic Selenium Nanoparticles from an Extract of Ginger towards Evaluation on Anti-Microbial and Anti-Oxidant Activities

Biogenic method of synthesis of nanoparticles is being preferred over the conventional chemical and physical methods due to its reduced toxicity towards the environment which uses living organisms like plants, microalgae and other microorganisms. The biomolecules present help in the reduction of Sodium Selenite to its elemental form Selenium nanoparticles. Z. officinale was used for the synthesis of selenium nanoparticles which was confirmed by the color change from pale yellow to red. The morphology of the nanoparticles was characterized by various techniques like SEM, TEM, DLS and AFM which revealed the size of the nanoparticles to be around 100-150 nm with a spherical shape, while the Zeta potential results also revealed its high stability nature. Its anti-microbial activity was tested against five bacterial species Escherichia coli, Klebsiella sp., Pseudomonas sp., Staphylococcus aureus and Proteus sp. The antibacterial activity of selenium nanoparticles was found to be significantly effective against Proteus sp. when compared with other species and thus the growth curve of Proteus sp. bacterial isolate treated with SeNPs was estimated. The Minimum Inhibitory Concentration of the Selenium nanoparticles against Proteus sp. showed that a concentration of about 250 μg/mL was required to establish its bactericidal activity. The antioxidant activity was also checked by using the DPPH assay. In the need of developing an eco-friendly, cost-effective and efficient biomedical agent that can also be compatible with pharmaceutical and industrial purposes was served through this paper.

Analytical monitoring of selenium nanoparticles green synthesis using photochemical vapor generation coupled with MIP-OES and UV–Vis spectrophotometry

Three synthesis routes of selenium nanoparticles (SeNPs), using glucose, ascorbic acid and yeast Saccharomyces boulardii, alternatively, as green chemistry reductants for ionic Se, have been successfully monitored using both continuous photochemical vapor generation (PCVG) coupled with MIP-OES and UV–Vis spectrophotometry. PCVG-MIP-OES allows for fast and selective determination of unreacted selenium(IV) oxyanion in the presence of SeNPs and matrix components, enabling accurate calculation of the yield of the SeNPs synthesis. For the analysis, these analyte ions were converted into volatile species by UV irradiation of their aqueous solution in the presence of 15% (v/v) acetic acid. Severe matrix effects were observed from organic matrix components leading to relatively high limit of detection for Se(IV) by PCVG-MIP-OES (0.52 mg L−1). Moreover, both the particle size in the range from 20 to 240 nm and particle number concentration up to 5 × 1017 SeNPs per mL were assessed based on UV–Vis spectra of SeNPs dispersions. The proposed monitoring protocol meets green chemistry requirements and allows for fast and selective determination of the yield of SeNPs synthesis.

A novel synthesis of selenium nanoparticles encapsulated PLGA nanospheres with curcumin molecules for the inhibition of amyloid β aggregation in Alzheimer's disease

The main factors of Alzheimer's disease (AD) are the cerebral accumulation and the formation of extracellular amyloid plaques. The Aβ peptides are highly able to accumulative and produce fibrils that are placed to form these plaques in the AD. The biological action and drug delivery properties of curcumin (Cur) nanoformulation in the Alzheimer's disease therapeutics can be developed by the altering surface of the Poly-lactide-co-glycolide (PLGA) polymer and encapsulation of selenium nanoparticles (Se NPs). The morphological structure, size distributions of nanospheres, chemical interactions between the polymer and nanoformulations of synthesized curcumin and Se NPs loaded PLGA nanospheres have been studied by using the techniques of analytical instruments. The microscopic and nano observation results of synthesized Cur loaded nanospheres are exhibited that the mono-dispersed distributions of particles with spherical shaped structure. The present drug delivery system of Cur loaded Se-PLGA nanospheres could be decreases the amyloid-β load in the brains samples of AD mice, and greatly cured the memory deficiency of the model mice. The specific binding of Cur loaded Se-PLGA nanospheres with Aβ plaques were visualized by fluorescence microscopic technique. Se-PLGA targeting delivery system to amyloid plaques might be providing the enhanced therapeutic efficacy in AD lesions, which was studied by using transgenic mice (5XFAD). In conclusion, Cur loaded Se-PLGA nanoformulation has been demonstrated that valued delivery system for the targeted delivery and effective way to treat AD.

Synthesis and Characterization of Nano Selenium Using Plant Biomolecules and Their Potential Applications

The present study reports the eco-friendly synthesis of selenium nanoparticles (SeNps) and their characterization. Synthesis of SeNps was carried out by incubating aqueous sodium selenite (Na2SeO3) with an alcoholic extract of guava (Psidium guajava) leaf. The biosynthesis was completed in 3 h which was confirmed by UV-Vis spectroscopy and the surface plasmon resonance observed at 381 nm. FTIR spectroscopy data reveals that ascorbic acid and phenolic compounds present in guava leaves are responsible for the synthesis of nanoparticles. Transmissions electron microscopy (TEM) analysis shows the synthesized SeNps are spherical, having a diameter in the range of 8–20 nm. The synthesized nanoparticles show antibacterial effect on both gram-positive and gram-negative bacteria. Scanning electron microscopy (SEM) reveals that SeNps disrupt the bacterial cell structure. The bactericidal effect was studied by fluorescence microscopy. The toxicity was analyzed by MTT assay against HepG2 cell and CHO cells lines. The nanoparticles were found to be biocompatible with potent antibacterial properties.

Selenite Reduction and the Biogenesis of Selenium Nanoparticles by Alcaligenesfaecalis Se03 Isolated from the Gut of Monochamus alternatus (Coleoptera: Cerambycidae).

In this study, a bacterial strain exhibiting high selenite (Na2SeO3) tolerance and reduction capacity was isolated from the gut of Monochamus alternatus larvae and identified as Alcaligenes faecalis Se03. The isolate exhibited extreme tolerance to selenite (up to 120 mM) when grown aerobically. In the liquid culture medium, it was capable of reducing nearly 100% of 1.0 and 5.0 mM Na2SeO3 within 24 and 42 h, respectively, leading to the formation of selenium nanoparticles (SeNPs). Electron microscopy and energy dispersive X-ray analysis demonstrated that A. faecalis Se03 produced spherical electron-dense SeNPs with an average hydrodynamic diameter of 273.8 ± 16.9 nm, localized mainly in the extracellular space. In vitro selenite reduction activity and real-time PCR indicated that proteins such as sulfite reductase and thioredoxin reductase present in the cytoplasm were likely to be involved in selenite reduction and the SeNPs synthesis process in the presence of NADPH or NADH as electron donors. Finally, using Fourier-transform infrared spectrometry, protein and lipid residues were detected on the surface of the biogenic SeNPs. Based on these observations, A. faecalis Se03 has the potential to be an eco-friendly candidate for the bioremediation of selenium-contaminated soil/water and a bacterial catalyst for the biogenesis of SeNPs.

Biosynthesis, characterization and antimicrobial activities assessment of fabricated selenium nanoparticles using Pelargonium zonale leaf extract

AbstractThe present study focuses on the biogenic synthesis of selenium nanoparticles (Se NPs) usingPelargonium zonaleleaf extract under microwave irradiation. Response surface methodology was used to evaluate the effects of the synthesis parameters, namely amounts of the leaf extract (0.5–2.5 ml) and amounts of the 10 mmsodium selenite solutions (15–65 ml), at constant microwave heating (4 min), on the concentration and particle size of the fabricated Se NPs, optimize the synthesis conditions and verify the generated models and the procedures. The obtained results indicated that Se NPs with preferable attributes of mean particle size (50 nm), zeta potential (−24.6 mV), absorbance [34.6% absorbance units (a.u.)] and broad absorption peak (319 nm) were formed at the optimum synthesis conditions including amounts of 1.48 ml and 15 mlPelargoniumleaf extract and sodium selenite solution, respectively. The antibacterial activities of the synthesized Se NPs againstEscherichia coliandStaphylococcus aureusindicated that the created NPs had higher antibacterial activities toward the Gram-positive bacteria. Furthermore, the synthesized Se NPs indicated higher antifungal activities againstColletotrichum coccodesandPenicillium digitatum.

Antimicrobial Activity of Selenium Nanoparticles Synthesized by Actinomycetes Isolated from Lombok Island Soil Samples

AbstractA total of 98 actinomycetes were isolated from the soil and litter samples collected from the cacao and coffee plantation in Lombok Island, West Nusa Tenggara, Indonesia. These isolates were screened for their antimicrobial activity. Among 98 isolated strains, only 24 isolates showed antimicrobial activity against test microorganisms of which 20.4% were active against Bacillus subtilis BTCC B-612, 14.3% against Staphylococcus aureus BTCC B-611, and 5.1% against Escherichia coli BTCC B-609. Out of these 24 isolates, 3 were found to be able to grow in medium containing 3 mM Selenium oxide of which the culture were changed color to red. Two of the best strains, L-155 and L-156, were selected for assessing production of Selenium nanoparticles. Bioreduction of selenium nanoparticles was confirmed by UV–visible spectrophotometer which showed peak between 300 and 320 nm. Biosynthesized selenium nanoparticle from isolate actinomycetes L-155 and L-156 were found to have a broad spectrum of activity against the tested microorganisms: Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Micrococcus luteus, and Candida albicans. This study showed rapid and eco-friendly synthesis of selenium nanoparticles from soil actinomycetes. Most of these active isolates revealed to possess antibacterial property.

Bacillus cereus, selenite-reducing bacterium from contaminated lake of an industrial area: a renewable nanofactory for the synthesis of selenium nanoparticles

BackgroundAn attempt was made to isolate selenite-reducing bacteria from a contaminated lake that receives industrial effluents and domestic sewage. The isolated dominant bacterial strain AJK3 was identified as Bacillus cereus, based on biochemical characterization and 16S rDNA sequencing. The time dependent selenium removal at different selenite concentrations monitored with ICP-AES indicates the substantial selenite reduction capability of the isolated strain. The selenium nanoparticles produced during the bacterial reduction of selenite were analyzed with UV–visible spectroscopy, X-ray diffraction, transmission electron microscopy, zeta potential measurement, Fourier transform infrared spectroscopy and Raman spectroscopy.ResultsThe nanoparticle synthesis was confirmed from the red colour emergence in culture broth and wide UV–vis peaks. The produced nanoparticles were polydisperse, spherical, size varied from 50 to 150 nm and the mean particle size was about 93 nm. The amorphous nature of the generated nanoparticles was confirmed from the Raman spectroscopy, XRD and SAED patterns. The IR data and zeta potential values substantiated the protein capping of the produced nanoparticles.ConclusionsThus, the present study suggests that the isolated bacterial strain can be exploited as a prospective, renewable, natural, nanofactory for the bacteriogenic synthesis of nanoparticles. Also, the study has application in bioremediation of selenite from the contaminated environment.

Biological Synthesis of Selenium Nanoparticles and Evaluation of their Bioavailability

ABSTRACT Nanoparticles due to their unique properties have attracted more attention and their bacterial biosynthesis is more favorable because is environmental friendly and the size and yield of nanoparticles can be optimized. The aim of the present study was biosynthesis of Selenium nanoparticles using Bacillus cereus. For this purpose, bacterial culture was prepared in the presence of sodium selenate solution and incubated (30°C, 24 h). The produced nanoparticles were purified through consequent centrifugation, washing with 0.9% NaCl, sonication, washing with Tris- HCl containing Sodium dodecyl sulfate (SDS) and finally isolation with water- octanol two phase systems. Then using Ultraviolet-Visible spectroscopy, dynamic light scattering (DLS), scaning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, nanoparticle production was confirmed. The bioavailability of nanoparticles was also investigated in rat. As a result of this study spherical selenium nanoparticles with a mean diameter of 170 nm were biosynthesized. MIC (minimum inhibitory concentration) and MBC (minimum bactericidal concentration) of selenium for Bacillus cereus were same and equal to 75mM. Absorption and secretion of nanoselenium was significantly higher than bulk Selenium (P<0.05). In conclusion in the present study without any chemical substance, spherical Selenium nanoparticles were produced that do not have any environmental contamination. Furthermore, the metabolism of these particles suggests higher absorption rate of them that facilitates its application in medicine and also veterinary medicine.

Biomolecules-mediated synthesis of selenium nanoparticles using Aspergillus oryzae fermented Lupin extract and gamma radiation for hindering the growth of some multidrug-resistant bacteria and pathogenic fungi

Biosynthesis of nanoparticles by fermented plants using microbes is an eco-friendly and cost-effective process. In this study, we used the fungus Aspergillus orayzae for the fermentation process. The aqueous extract of fermented Lupin (AEFL) possesses the ability to reduce selenium ion in the presence of gamma rays evidenced by the color changes to red. Elemental composition, surface morphology, size determenation, and identity of selenium nanoparticles (SeNPs) were verified by UV–Vis., TEM, DLS, XRD, EDX, SEM and FT-IR. Antimicrobial activity of SeNPs was tested towards multidrug-resistant (MDR) bacteria, and some pathogenic fungi. TEM with DLS analysis confirmed the formation of sphere isotropic, poly-dispersed SeNPs with average particle size 55.0 nm. The nucleation and mechanism of SeNPs production was discussed. Our results revealed that, gamma ray (30.0 kGy) was played a significant role in SeNPs synthesis. The synthesized SeNPs were active towards Acinetobacter calcoaceticus (15.0 mm ZOI) and Staphylococcus aurus (16.6 mm ZOI). Additionally, SeNPs were inhibiting Candida albicans (15.3 mm ZOI) and mycotoxin producing Aspergillus flavus (29.6 mm ZOI). Depending on the unique characteristics, and the novelty in biosynthesis process of SeNPs, it must be candidates in biomedicine, prevent food spoilage, cosmetics, and pharmaceutics as green antimicrobial agent.

Laser synthesis of selenium nanoparticles in liquid monomers

The paper presents the results of selenium nanoparticles synthesis in various liquid monomers by laser ablation. The following substances were selected as the condensation liquids for laser ablation: isodecyl acrylate (IDA, Isodecylacrylate, Aldrich), carboxyethyl acrylate (2Car, 2-carboxyethyl acrylate, Aldrich), ethylene glycol phenyl acrylate (Aldrich), ethylene glycol phenyl acrylate, an available blend of Ebecryl monomers (Cytec Industries Inc.), currently one of the possible components of modern lacquer coatings for nail plates. Thus, a method is proposed for simultaneous synthesis and incorporation of selenium nanoparticles into a polymer matrix. It is established by scanning microscopy method that the sizes of the obtained nanoparticles are from 50 to 200 nm. Infrared spectroscopy results of obtained colloidal solutions showed zero interactions of selenium nanoparticles with monomers. Stable colloidal solutions of selenium nanoparticles were obtained, and solid polymer films promising for biomedical applications were synthesized. The polymerization of colloidal solutions with added monomers and/or mixtures of oligomers was carried out using photo initiator of polymerization 2.2-dimethoxy-2-fenilatsetofenol, sensitive in the UV region (365 nm). The results of IR spectroscopy of the obtained colloidal solutions and polymer nanocomposites showed the absence of interactions of selenium nanoparticles with monomers and polymer matrices. Such nanocomposites could be perspective for biomedical applications, for example, as fungicidal coatings of different surfaces.

Synergistic antifungal effect of chitosan-stabilized selenium nanoparticles synthesized by pulsed laser ablation in liquids against Candida albicans biofilms.

BackgroundCandida albicans is a major opportunistic fungal pathogen. One of the most important virulence factors that contribute to the pathogenesis of candidiasis is its ability to form biofilms. A key characteristic of Candida biofilms is their resistance to antifungal agents. Due to significant morbidity and mortality rates related to biofilm-associated drug resistance, there is an urgency to develop novel nanotechnology-based approaches preventing biofilm-related infections.MethodsIn this study, we report, for the first time, the synthesis of selenium nanoparticles by irradiating selenium pellets by nanosecond pulsed laser ablation in liquid chitosan as a capping agent. Synergy of the fungicidal effect of selenium nanoparticles and chitosan was quantified by the combination index theorem of Chou–Talalay.ResultsThis drug combination resulted in a potent fungicidal effect against a preformed C. albicans biofilm in a dose–response manner. By advanced electron microscopy techniques, we documented the adhesive and permeabilizing properties of chitosan, therefore allowing selenium nanoparticles to enter as the cell wall of the yeast became disrupted and distorted. Most importantly, we demonstrated a potent quantitative synergistic effect when compounds such as selenium and chitosan are combined.ConclusionThese chitosan-stabilized selenium nanoparticles could be used for ex vivo applications such as sterilizers for surfaces and biomedical devices.

Preparation, characteristics and antioxidant activity of polysaccharides and proteins-capped selenium nanoparticles synthesized by Lactobacillus casei ATCC 393

Selenium (Se) is an essential element nutrient for human and animal health. Biogenic selenium nanoparticles (SeNPs) by microorganism possesses unique physical and chemical properties and biological activities compared to inorganic selenium and organic selenium. The study was conducted to establish a green, efficient and low-cost biotechnology for biogenic synthesis of SeNPs by Lactobacillus casei ATCC 393 (L. casei 393), and investigate its characteristics and antioxidant activities in vitro. The results showed that L. casei 393 transforms sodium selenite to SeNPs under anaerobic conditions. Moreover, 50–80 nm SeNPs were accumulated in the intracellular L. casei 393. The whole bacteria present distinct bright red color. SeNPs were isolated and characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray photoelectron spectroscopy (XPS), and fourier transform infrared spectroscopy (FT-IR). The results showed that the extracted SeNPs were capped by proteins and polysaccharides. Extracted biogenic SeNPs by L. casei 393 at a concentration less than 25 μg Se/mL had no cytotoxicity on the growth and proliferation of human normal epithelial cell (NCM460). The toxicity order of different selenium forms was: Sodium selenite > Selenium methionine > SeNPs synthesized by L. casei 393. Moreover, biogenic SeNPs by L. casei 393 induced HepG2 cells apoptosis via caspase cascade signaling and endocytosis of SeNPs. Moreover, SeNPs alleviated diquat or hydrogen peroxide (H2O2)-caused oxidative damage in intestinal epithelial cells, and reduced malondialdehyde (MDA) concentration and increased glutathione peroxidase (GPx) activity in culture medium. The findings suggest that biomolecules capped-SeNPs synthesized by probiotic L. casei 393 possess significant antioxidant and anticancer activities, and probiotic bacteria can provide a better alternative to synthesize biogenic elemental selenium particles with potential applications as anticancer and antioxidant agents.

Extracellular Synthesis of Selenium Nanoparticles from an Actinomycetes Streptomyces griseoruber and Evaluation of its Cytotoxicity on HT-29 Cell Line.

Selenium nanoparticles (SeNPs) have gained significant importance because of its bioavailability, least toxicity, its interaction with proteins and its biocompatibility. In the present study, the extracellular synthesis of SeNPs was carried out by using culture supernatant of Streptomyces griseoruber, an Actinomycetes member isolated from the soil and cytotoxicity was tested on HT-29 cell line. Culture supernatant was mixed with 1mM sodium selenite for the biosynthesis of SeNPs. Characterisation of the synthesised SeNPs was done by UV-Visible spectrophotometer, FTIR, XRD, DLS and HR-TEM. The cytotoxicity of nanoparticles on HT-29 cell line was studied by MTT assay and with different staining procedure. Bioreduction of SeNPs was confirmed by UV-Visible spectrophotometer that showed the peak at 575 nm. Size and distribution of the biosynthesised SeNPs were analysed by HR-TEM that showed the formation of particle size in the range of 100-250nm. The synthesised SeNPs showed good cytotoxic activity against HT-29 cell line with 40.5%, 33% and 23.7% of cell viability at 2μg/ ml, 4μg/ml and 30μg/ml concentration respectively. The present study reports the simple and eco-friendly synthesis of SeNPs that showed good cytotoxic activity against HT-29 cell line suggesting that biogenic SeNPs could be a potential chemotherapeutic agent.

Synthesis and characterization of biogenic selenium nanoparticles with antimicrobial properties made by Staphylococcus aureus, methicillin‐resistant Staphylococcus aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa

Antimicrobial resistance is a global concern that affects more than two million people each year. Therefore, new approaches to kill bacteria are needed. One of the most promising methodologies may come from metallic nanoparticles, since bacteria may not develop a resistance to these nanostructures as they do for antibiotics. While metallic nanoparticle synthesis methods have been well studied, they are often accompanied by significant drawbacks such as cost, extreme processing conditions, and toxic waste production since they use harsh chemicals such as corrosive agents (hydrazine) or strong acids (hydrochloride acid). In this work, we explored the environmentally safe synthesis of selenium nanoparticles, which have shown promise in killing bacteria. Using Escherichia coli, Pseudomonas aeruginosa, Methicillin-resistance Staphylococcus aureus, and S. aureus, 90-150 nm average diameter selenium nanoparticles were synthesized using an environmentally safe approach. Nanoparticles were characterized using transmission electron microscopy, energy dispersive X-ray spectroscopy to determine the chemical composition, and inductively coupled plasma mass spectrometry to validate chemistry. Nanoparticles were also characterized and tested for their ability to inhibit bacterial growth. A decay in bacterial growth after 24 h was achieved against both S. aureus and E. coli at biogenic selenium nanoparticle concentrations from 25 to 250 µg/mL and showed no significant cytotoxicity effect against human dermal fibroblasts for 24 h. Bacteria were able to synthesize selenium nanoparticles through the use of different functional structures within the organisms, mainly enzymes such as selenite reductases. Therefore, biogenic selenium nanoparticles made by bacteria represent a viable approach to reduce bacteria growth without antibiotics overcoming the drawbacks of synthetic methods that employ toxic chemicals. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1400-1412, 2018.

A comparative study on the green synthesis of selenium nanoparticles and evaluation of their antioxidant potential using Allium sativum and Aloe vera extracts

A comparative study on the green synthesis of selenium nanoparticles and evaluation of their antioxidant potential using <i>Allium sativum</i> and <i>Aloe vera</i> extracts