Green synthesis of selenium nanoparticles conjugated Clausena dentata plant leaf extract and their insecticidal potential against mosquito vectors

Biosynthesis of Selenium Nanoparticles (via Bacillus subtilis BSN313), and Their Isolation, Characterization, and Bioactivities

Among the trace elements, selenium (Se) has great demand as a health supplement. Compared to its other forms, selenium nanoparticles have minor toxicity, superior reactivity, and excellent bioavailability. The present study was conducted to produce selenium nanoparticles (SeNPs) via a biosynthetic approach using probiotic Bacillus subtilis BSN313 in an economical and easy manner. The BSN313 exhibited a gradual increase in Se reduction and production of SeNPs up to 5-200 µg/mL of its environmental Se. However, the capability was decreased beyond that concentration. The capacity for extracellular SeNP production was evidenced by the emergence of red color, then confirmed by a microscopic approach. Produced SeNPs were purified, freeze-dried, and subsequently characterized systematically using UV-Vis spectroscopy, FTIR, Zetasizer, SEM-EDS, and TEM techniques. SEM-EDS analysis proved the presence of selenium as the foremost constituent of SeNPs. With an average particle size of 530 nm, SeNPs were shown to have a -26.9 (mV) zeta potential and -2.11 µm cm/Vs electrophoretic mobility in water. SeNPs produced during both the 24 and 48 h incubation periods showed good antioxidant activity in terms of DPPH and ABST scavenging action at a concentration of 150 µg/mL with no significant differences (p > 0.05). Moreover, 200 µg/mL of SeNPs showed antibacterial reactivity against Escherichia coli ATCC 8739, Staphylococcus aureus ATCC 9027, and Pseudomonas aeruginosa ATCC 25923. In the future, this work will be helpful to produce biogenic SeNPs using probiotic Bacillus subtilis BSN313 as biofactories, with the potential for safe use in biomedical and nutritional applications.

The Advancing of Selenium Nanoparticles Against Infectious Diseases

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

Using Green Biosynthesized Lycopene-Coated Selenium Nanoparticles to Rescue Renal Damage in Glycerol-Induced Acute Kidney Injury in Rats

Purpose

Selenium nanoparticles (SeNPs) have recently gained much attention in nanomedicine applications owing to their unique biological properties. Biosynthesis of SeNPs using nutraceuticals as lycopene (LYC) maximizes their stability and bioactivities. In this context, this study aimed to elucidate the renoprotective activity of SeNPs coated with LYC (LYC-SeNPs) in the acute kidney injury (AKI) model.

Methods

Rats were divided into six groups: control, AKI (glycerol-treated), AKI+sodium selenite (Na₂SeO₃; 0.5 mg/kg), AKI+LYC (10 mg/kg), AKI+LYC-SeNPs (0.5 mg/kg) and treated for 14 days.

Results

Glycerol treatment evoked significant increases in rhabdomyolysis-related markers (creatine kinase and LDH). Furthermore, relative kidney weight, Kim-1, neutrophil gelatinase-associated lipocalin (NGAL), serum urea, and creatinine in the AKI group were elevated. Glycerol-injected rats displayed declines in reduced glutathione level, and superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activities, paralleled with downregulations in Nfe2l2 and Hmox-1 expressions and high renal MDA and NO contents. Glycerol-induced renal inflammation was evident by rises in TNF-α, IL-1β, IL-6, and upregulated Nos2 expression. Also, apoptotic (elevated caspase-3, Bax, and cytochrome-c with lowered Bcl-2) and necroptotic (elevated Pipk3 expression) changes were reported in damaged renal tissue. Co-treatment with Na₂SeO₃, LYC, or LYC-SeNPs restored the biochemical, molecular, and histological alterations in AKI. In comparison with Na₂SeO₃ or LYC treatment, LYC-SeNPs had the best nephroprotective profile.

Conclusion

Our findings authentically revealed that LYC-SeNPs co-administration could be a prospective candidate against AKI-mediated renal damage via antioxidant, anti-inflammatory, anti-apoptotic and anti-necroptotic activities.

Selenium-Containing Polysaccharides—Structural Diversity, Biosynthesis, Chemical Modifications and Biological Activity

Selenosugars are a group of sugar derivatives of great structural diversity (e.g., molar masses, selenium oxidation state, and selenium binding), obtained as a result of biosynthesis, chemical modification of natural compounds, or chemical synthesis. Seleno-monosaccharides and disaccharides are known to be non-toxic products of the natural metabolism of selenium compounds in mammals. In the case of the selenium-containing polysaccharides of natural origin, their formation is also postulated as a form of detoxification of excess selenium in microorganisms, mushroom, and plants. The valency of selenium in selenium-containing polysaccharides can be: 0 (encapsulated nano-selenium), IV (selenites of polysaccharides), or II (selenoglycosides or selenium built into the sugar ring to replace oxygen). The great interest in Se-polysaccharides results from the expected synergy between selenium and polysaccharides. Several plant- and mushroom-derived polysaccharides are potent macromolecules with antitumor, immunomodulatory, antioxidant, and other biological properties. Selenium, a trace element of fundamental importance to human health, has been shown to possess several analogous functions. The mechanism by which selenium exerts anticancer and immunomodulatory activity differs from that of polysaccharide fractions, but a similar pharmacological effect suggests a possible synergy of these two agents. Various functions of Se-polysaccharides have been explored, including antitumor, immune-enhancement, antioxidant, antidiabetic, anti-inflammatory, hepatoprotective, and neuroprotective activities. Due to being non-toxic or much less toxic than inorganic selenium compounds, Se-polysaccharides are potential dietary supplements that could be used, e.g., in chemoprevention.

Selenium nanoparticle synthesis from endangered medicinal herb (Enicostema axillare)

Green synthesis of selenium nanoparticles (SeNPs) was achieved by a simple biological procedure using the reducing power of E. axillare leaf extract. This method is capable of producing SeNPs in a size range of around 56.23-98.18 nm, under ambient lab condition. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Energy-dispersive X-Ray (EDX). To check the potential hazards of nanotoxicity median lethal concentration (LC50) and Na + /K + -ATPase activity was assessed on zebra fish which showed the LC50 of 258.72 ppm for 96 h and Na + /K + -ATPase seems to significantly decrease with increase in SeNPs concentration. Antibactericidal activity explored the use of SeNPs against wide range of pathogens. Cytotoxicity of SeNPs was assayed against human lung cancer cells (A549) confirmed that SeNPs are able to inhibit the cell growth by dose-dependent manner. In conclusion, green synthesized selenium nanoparticles are less toxic and harmless. This is the first report on green synthesized selenium nanoparticles using E. axillare possessing anti-bacterial and anti-cancer activity.

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

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

Biocompatibility assessment of silver chloride nanoparticles derived from Padina gymnospora and its therapeutic potential

The objective of the present work was to improve the biological activity of Padina gymnospora. In the current study, silver chloride nanoparticles have been synthesized using the aqueous extract of Padina gymnospora and further characterized by ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, x-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy and atomic force microscope. Further, the hemolytic activity and eco-toxicity of silver chloride nanoparticles analyzed. The synthesized silver chloride nanoparticles were found to be mono-dispersed and spherical with an average size of 11.5–32.86 nm. The particles showed an anticancer effect in a dose-dependent manner against breast cancer cell line (MCF-7 cell lines) (IC50 = 31.37 μg ml−1). In addition, it showed the larvicidal activity against Aedes aegypti at a lower dose (3.92 μg ml−1) than that of the aqueous extract (13.01 μg ml−1). Nanoparticles also exhibited greater antimicrobial activity for both bacterial and fungal pathogens. The synthesized silver chloride nanoparticles showed a maximum zone of inhibition, i.e., 31 mm for Candida albicans followed and 27 mm for vancomycin resistance Enterococcus faecalis.The results suggest the possible use of synthesized silver nanoparticles with P. gymnospora as therapeutic agent for breast cancer, dengue vector control and as antimicrobial agent.

Green synthesis of selenium nanoparticles mediated from Ceropegia bulbosa Roxb extract and its cytotoxicity, antimicrobial, mosquitocidal and photocatalytic activities

The present study is to design an eco-friendly mode to rapidly synthesize selenium nanoparticles (SeNPs) through Ceropegia bulbosa tuber's aqueous extracts and confirming SeNPs synthesis by UV-Vis spectroscopy, FT-IR, XRD, FE-SEM-EDS mapping, HR-TEM, DLS and zeta potential analysis. In addition, to assess the anti-cancer efficacy of the SeNPs against the cultured MDA-MB-231, as studies have shown SeNPs biosynthesis downregulates the cancer cells when compared to normal HBL100 cell lines. The study observed the IC₅₀ value of SeNPs against MDA-MB-231 cells was 34 µg/mL for 48 h. Furthermore, the SeNPs promotes growth inhibitory effects of certain clinical pathogens such as Bacillus subtilis and Escherichia coli. Apart, from this the SeNPs has shown larvicidal activity after 24 h exposure in Aedes albopitus mosquito's larvae with a maximum of 250 g/mL mortality concentration. This is confirmed by the histopathology results taken at the 4th larval stage. The histopathological studies revealed intense deterioration in the hindgut, epithelial cells, mid gut and cortex region of the larvae. Finally, tried to investigate the photocatalytic activity of SeNPs against the toxic dye, methylene blue using halogen lamp and obtained 96% degradation results. Withal computational study SeNPs was shown to exhibit consistent stability towards breast cancer protein BRCA2. Overall, our findings suggest SeNPs as a potent disruptive agent for MDA-MB-231 cells, few pathogens, mosquito larvae and boosts the photocatalytic dye degradation.

Biomedical Potential of Plant-Based Selenium Nanoparticles: A Comprehensive Review on Therapeutic and Mechanistic Aspects

Selenium nanoparticles (SeNPs) have advantages over other nanomaterials because of the promising role of selenium in the stabilization of the immune system and activation of the defense response. The use of SeNPs and their supplements not only have pharmacological significance but also boost and prepare the body's immune system to fight the pathogens. This review summarizes the recent progress in the biogenesis of plant-based SeNPs by using various plant species and the role of secondary metabolites on their biocompatible functioning. Phyto-synthesis of SeNPs results in the synthesis of nanomaterials of various, size, shape and biochemical nature and has advantages over other routine physical and chemical methods because of their biocompatibility, eco-friendly nature and in vivo actions. Unfortunately, the plant-based SeNPs failed to attain considerable attention in the pharmaceutical industry. However, a few studies were performed to explore the therapeutic potential of the SeNPs against various cancer cells, microbial pathogens, viral infections, hepatoprotective actions, diabetic management, and antioxidant approaches. Further, some of the selenium-based drug delivery systems are developed by engineering the SeNPs with the functional ligands to deliver drugs to the targeted sites. This review also provides up-to-date information on the mechanistic actions that the SeNPs adopt to achieve their designated tasks as it may help to develop precision medicine with customized treatment and healthcare for the ailing population.

Potentialities of selenium nanoparticles in biomedical science

Selenium nanoparticles (SeNPs) have revolutionized biomedical domain and are still developing rapidly. Hence, this perspective elaborates SeNPs properties, synthesis, and biomedical applications, together with their potential for management of SARS-CoV-2.

Synthesis and Characterization of Black Currant Selenium Nanoparticles (Part I)

The present study aimed to synthesize selenium nanoparticles (SeNPs) using aqueous extract of black currant as a reducing agent. The green synthesized black currant selenium nanoparticles (BCSeNPs) were identified by color change. The characterization of SeNPs was achieved by Ultraviolet-visible (UV–VIS) spectroscopy, scanning electron microscopy (SEM), X–ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR). These tests were used to detect: stability, morphology, size, crystalline nature, and functional groups present on the surface of BCSeNPs. The results revealed appearance of the brick-red color indicating the specific color of selenium nanoparticles, and UV-Vis spectroscopy showed band absorbance at 265 nm of intense surface plasmon resonance manifesting the formation and stability of the prepared BCSeNPs. The SEM image showed the prevalence of spherical selenium nanosized, XRD at 2θ revealed crystallin selenium nanoparticles, the size was in the average of 18-50 nm. Furthermore, FTIR revealed the presence of functional groups of the plant which act as stabilizing and reducing agents. In conclusion, the aqueous black currant extract can act as a reducing and capping agent to synthesize BCSeNPs in nano-scale size by a simple method

Efficacy of Antimicrobial and Larvicidal Activities of Green Synthesized Silver Nanoparticles Using Leaf Extract of Plumbago auriculata Lam

This work reports the synthesis of silver nanoparticles (AgNPs) using aqueous extract of Plumbago auriculata, and evaluates their antibacterial and larvicidal activities. The synthesized silver nanoparticles were characterized by various spectroscopy techniques, such as FTIR, XRD, TEM, EDX, Zeta potential, and DLS. The synthesized AgNPs exhibited significant antibacterial activity against Gram-positive and Gram-negative bacteria, such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae. Furthermore, synthesized nanoparticles inhibited the fourth instars larvae of Aedes aegypti and Culex quinquefasciatus at the concentration of 45.1 and 41.1 µg/mL respectively. Results of dose-dependent studies showed that synthesized nanoparticles were also effective at low concentrations. Molecular docking studies performed with the salivary protein and odorant-binding protein of Aedes aegypti and Culex quinquefasciatus demonstrated that the naphthoquinone compound plumbagin exhibited reliable binding affinity towards the two enzymes. The findings thus reveal that the plant extract and its nanoparticles can be a better alternative to available chemicals to control mosquitos.

Biogenic nanoparticles: a comprehensive perspective in synthesis, characterization, application and its challenges

BACKGROUND

Translating the conventional scientific concepts into a new robust invention is a much needed one at a present scenario to develop some novel materials with intriguing properties. Particles in nanoscale exhibit superior activity than their bulk counterpart. This unique feature is intensively utilized in physical, chemical, and biological sectors. Each metal is holding unique optical properties that can be utilized to synthesize metallic nanoparticles. At present, versatile nanoparticles were synthesized through chemical and biological methods. Metallic nanoparticles pose numerous scientific merits and have promising industrial applications. But concerning the pros and cons of metallic nanoparticle synthesis methods, researchers elevate to drive the synthesis process of nanoparticles through the utilization of plant resources as a substitute for use of chemicals and reagents under the theme of green chemistry. These synthesized nanoparticles exhibit superior antimicrobial, anticancer, larvicidal, leishmaniasis, wound healing, antioxidant, and as a sensor. Therefore, the utilization of such conceptualized nanoparticles in treating infectious and environmental applications is a warranted one.

CONCLUSION

Green chemistry is a keen prudence method, in which bioresources is used as a template for the synthesis of nanoparticles. Therefore, in this review, we exclusively update the context of plant-based metallic nanoparticle synthesis, characterization, and applications in detailed coverage. Hopefully, our review will be modernizing the recent trends going on in metallic nanoparticles synthesis for the blooming research fraternities.

Production and Use of Selenium Nanoparticles as Fertilizers

The synergy problem was discussed linking Se nanoparticles and different soil fertility agents. Se zero-valent-state nanoparticles were investigated as fertilizers and antioxidants. A technology was proposed for producing Se zero-valent-state nanoparticles. Se nanoparticles were obtained by laser ablation of Se in water using a fiber ytterbium laser, with a wavelength between 1060 and 1070 nm, a pulse repetition rate of 20 kHz, a pulse duration of 80 ns, and an average power of 20 W, and a copper vapor laser with wavelengths of 510.6 and 578.2 nm and an average power of 8 W. The main particle mass part shifted from 800 nm to a size less than 100 nm, corresponding to the increase in the laser fragmentation time. The resulting nanoparticles were monodisperse in size and mass. The Se nanoparticle water suspension was introduced into the soil. The soil Se nanoparticle concentrations were about 1, 5, 10, and 25 μg kg-1. An experiment was carried out in a climate chamber in two series: (1) growing plants in soil imitating the standard organogenesis environment conditions such as illumination of 16 h per day, temperature of 22 °C, soil humidity of 25% SDW, and an experiment duration of 30 days and (2) growing plants in soil under changing environmental conditions of organogenesis. The standard environmental conditions for the first 10 days are illumination of 16 h day-1, temperature of 22 °C, and soil humidity of 25% SDW. The plant stress for 5 days is hyperthermia of 40 °C. The standard environmental conditions for the next 15 days are illumination of 16 h day-1, temperature of 22 °C, and soil humidity of 25% SDW. At standard organogenesis, the plant leaf plate surface area was 30 ± 2 cm2 in the control option, and the Se nanoparticle doses were correspondingly 1 μg kg-1 for 32 ± 3 cm2, 5 μg kg-1 for 37 ± 2 cm2, 10 μg kg-1 for 38 ± 3 cm2, and 25 μg kg-1 for 28 ± 4 cm2. Hyperthermia stressed plant growth was studied. The highest plant growth rate was in Se nanoparticle concentrations of 5 and 10 μg kg-1. The eggplant growth on the soil with the Se nanoparticle addition at a concentration of 10 μg kg-1 of leaf plate surface area was twice compared to the eggplant growth in untreated soil. The same was for tomato plants. The leaf plate surface area of the cucumber plant grown using Se nanoparticles was 50% higher compared to the control option. The Biogeosystem technique methodology of 20-45 cm soil-layer intrasoil milling for soil multilevel aggregate system formation and intrasoil pulse continuous-discrete watering for soil water regime control was proposed for the Se nanoparticles for better function in the real soil, providing a synergy effect of soil mechanical processing, nanoparticles, humic substances, and polymicrobial biofilms on soil fertility.

Leaf Extract of Dillenia indica as a Source of Selenium Nanoparticles with Larvicidal and Antimicrobial Potential toward Vector Mosquitoes and Pathogenic Microbes

Chikungunya, dengue, Zika, malaria, Japanese encephalitis, filariasis, West Nile, etc. are mosquito transmitted diseases that have killed millions of people worldwide, and millions of people are at risk of these diseases. Control of the mosquitoes, such as Aedes aegypti and Culex quinquefasciatus, is challenging due to their development of resistance to synthetic insecticides. The habitats of the young mosquitoes are also the habitats for foodborne pathogens like Staphylococcus aureus (MTCC96) and Serratia marcescens (MTCC4822). The present study was aimed at synthesizing eco-friendly green nanoparticles using Dillenia indica leaf broth and analyzing its efficacy in controlling the vector mosquitoes A. aegypti and C. quinquefasciatus, as well as the microbial pathogens St. aureus and Se. marcescens. The formation of selenium nanoparticles (SeNps) was confirmed using UV-Vis spectroscopy (absorption peak at 383.00 nm), Fourier transform infrared radiation (FTIR spectrum peaks at 3177, 2114, 1614, 1502, 1340, 1097, 901, 705, and 508 cm−1), X-ray diffraction (diffraction peaks at 23.3 (100), 29.6 (101), 43.5 (012), and 50.05 (201)), and scanning electron microscopy (oval shaped). The size of the nanoparticles and their stability were analyzed using dynamic light scattering (Z-Average value of 248.0 nm) and zeta potential (−13.2 mV). The SeNps disorganized the epithelial layers and have broken the peritrophic membrane. Histopathological changes were also observed in the midgut and caeca regions of the SeNPs treated A. aegypti and C. quinquefasciatus larvae. The SeNps were also active on both the bacterial species showing strong inhibitory zones. The present results will explain the ability of SeNps in controlling the mosquitoes as well as the bacteria and will contribute to the development of multi potent eco-friendly compounds.

In vitro and in vivo toxicity assessment of selenium nanoparticles with significant larvicidal and bacteriostatic properties

In the present study, we investigated the larvicidal and bacteriostatic activity of biosynthesized selenium nanoparticles using aqueous berry extract of Murraya koenigii (Mk-Se NPs). The synthesized Mk-Se NPs were characterized using UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. XRD analysis revealed the crystalline nature of Mk-Se NPs as hexagonal. The FTIR spectra of Mk-Se NPs exhibited a strong peak at 3441 cm^-1 corresponding to the OH group. SEM and TEM analysis showed that the Mk-Se NPs were spherical in shape with a size between 50 and 150 nm. EDX peaks confirm the presence of 73.38% of selenium and 26.62% of oxide in Mk-Se NPs. Mk-Se NPs showed significant larvicidal property against the 4th instar larvae of a dengue fever-causing vector Aedes aegypti with LC_50- - 3.54 μg mL^-1 and LC_90- - 8.128 μg mL^-1 values. Mk-Se NPs displayed anti-bacterial activity against Gram-positive (Enterococcus faecalis &Streptococcus mutans) and Gram-negative (Shigella sonnei &Pseudomonas aeruginosa) bacteria at 40 and 50 μg mL^-1. In addition, Mk-Se NPs reduced bacterial biofilm thickness extensively at 25 μg mL^-1. The high antioxidant property at 50 μg mL^-1 and low hemolysis activity till 100 μg mL^-1 proved the biocompatible nature of Mk-Se NPs. In vitro and in vivo toxicity assessment of Mk-Se NPs showed low cytotoxicity against RAW 264.7 macrophages and Artemia nauplii. Together, our results suggest the potential application of Mk-Se NPs as a nano-biomedicine.

Phytofabrication of Selenium Nanoparticles From Emblica officinalis Fruit Extract and Exploring Its Biopotential Applications: Antioxidant, Antimicrobial, and Biocompatibility

In the present study, phytofabricated selenium nanoparticles (PF-SeNPs) were prepared from aqueous fruit extract of Emblica officinalis in a facile, green, economic, tactic and eco-friendly way. The aqueous fruit extract of E. officinalis was found to be rich with various secondary metabolites including phenolics (59.18 ± 2.91 mg gallic acid equivalents/g), flavonoids (38.50 ± 2.84 mg catechin equivalents/g), and tannins (44.28 ± 3.09 mg tannic acid equivalents/g) and determined that highly appropriate for the biosynthesis of nanoparticles. The facile phytofabrication of PF-SeNPs was confirmed by UV-visible and FTIR spectroscopic analysis. The XRD pattern and Raman spectroscopy showed that synthesized PF-SeNPs were amorphous in nature. The Zeta potential analysis confirmed that PF-SeNPs were negatively charged (-24.4 mV). The DLS analysis revealed that PF-SeNPs were in nano size and less aggregated with poly-dispersity index of less than 0.2. The SEM images depicted that PF-SeNPs were spherical in shape. The EDX analysis revealed that PF-SeNPs were constituted with Se (61.60%), C (29.96%), and O (4.41%). The HR-TEM analysis determined that PF-SeNPs were in nano size with an average diameter of 15–40 nm. The PF-SeNPs have offered fascinating bio-potential applications, such as antioxidant, antimicrobial and biocompatibility. They have also exhibited dose-dependent free radical scavenging activity, and EC50 was determined as 15.67 ± 1.41 and 18.84 ± 1.02 μg/mL for DPPH and ABTS assays, respectively. The PF-SeNPs has also shown the wide range of antimicrobial activity on foodborne pathogens, and it was found to be highly efficient on fungi followed by Gram-positive and Gram-negative bacteria. The biocompatibility of PF-SeNPs was assessed in N2a cells with much higher IC50 value (dose required to inhibit 50% of cell viability) compared to sodium selenite. Also, mitochondrial membrane potential (MMP) and caspase-3 were much less altered on treatment of PF-SeNPs related to sodium selenite. The cytotoxic studies clearly determined that PF-SeNPs was much less toxic and safer related to sodium selenite. Thus, PF-SeNPs could find suitable application as antioxidant and antimicrobial agent in food, biomedical, and pharmaceutical industry.

Microbial exopolymer-capped selenium nanowires - Towards new antibacterial, antibiofilm and arbovirus vector larvicides?

Arboviral diseases and microbial pathogens resistant to commercially available drugs are on the rise. Herein, a facile microbial-based approach was developed to synthesize selenium nanowires (Se NWs) using microbial exopolymer (MEP) extracted from the Bacillus licheniformis (probiotic bacteria). MEP-Se NWs were characterized using UV-Visible, XRD, FTIR, HR-TEM, FE-SEM and EDX. An UV-Visible peak was detected at 330 nm while XRD spectrum data pointed out the crystalline nature of MEP-Se NWs. FTIR spectrum revealed functional groups with strong absorption peaks in the range 3898.52-477.97 cm^-1. FE-SEM and HR-TEM revealed that the obtained structures were nanowires of 10-30 nm diameter. Se presence was confirmed by EDX analysis. MEP-Se NWs at 100 μg/ml highly suppressed the growth of both Gram ^(-) and Gram ⁽⁺⁾ bacteria. Further, microscopic analysis evidenced that 75 μg/ml MEP-Se NWs suppressed biofilm formation. Hemolytic assays showed that MEP-Se NWs were moderately cytotoxic. In addition, LC₅₀ values lower than 10 μg/ml were estimated testing MEP-Se NWs on both Aedes aegypti and Culex quinquefasciatus 3rd instar larvae. Morphological and histological techniques were used to elucidate on the damages triggered in mosquito tissues, with special reference to midgut, post-exposure to MEP-Se NWs. Therefore, based on our findings, MEP-Se NWs can be considered for entomological and biomedical applications, with special reference to the management of biofilm forming microbial pathogens and arbovirus mosquito vectors.

Secondary Metabolites in the Green Synthesis of Metallic Nanoparticles

The ability of organisms and organic compounds to reduce metal ions and stabilize them into nanoparticles (NPs) forms the basis of green synthesis. To date, synthesis of NPs from various metal ions using a diverse array of plant extracts has been reported. However, a clear understanding of the mechanism of green synthesis of NPs is lacking. Although most studies have neglected to analyze the green-synthesized NPs (GNPs) for the presence of compounds derived from the extract, several studies have demonstrated the conjugation of sugars, secondary metabolites, and proteins in these biogenic NPs. Despite several reports on the bioactivities (antimicrobial, antioxidant, cytotoxic, catalytic, etc.) of GNPs, only a handful of studies have compared these activities with their chemically synthesized counterparts. These comparisons have demonstrated that GNPs possess better bioactivities than NPs synthesized by other methods, which might be attributed to the presence of plant-derived compounds in these NPs. The ability of NPs to bind with organic compounds to form a stable complex has huge potential in the harvesting of precious molecules and for drug discovery, if harnessed meticulously. A thorough understanding of the mechanisms of green synthesis and high-throughput screening of stabilizing/capping agents on the physico-chemical properties of GNPs is warranted to realize the full potential of green nanotechnology.

Nano-selenium and its nanomedicine applications: a critical review

Traditional supplements of selenium generally have a low degree of absorption and increased toxicity. Therefore, it is imperative to develop innovative systems as transporters of selenium compounds, which would raise the bioavailability of this element and allow its controlled release in the organism. Nanoscale selenium has attracted a great interest as a food additive especially in individuals with selenium deficiency, but also as a therapeutic agent without significant side effects in medicine. This review is focused on the incorporation of nanotechnological applications, in particular exploring the possibilities of a more effective way of administration, especially in selenium-deficient organisms. In addition, this review summarizes the survey of knowledge on selenium nanoparticles, their biological effects in the organism, advantages, absorption mechanisms, and nanotechnological applications for peroral administration.

Synthesis and antioxidant properties of Lycium barbarum polysaccharides capped selenium nanoparticles using tea extract

Selenium nanoparticles (SeNPs) have attracted increasing interest over the last decades because of their activities on redox balance in human body. However, the SeNPs tend to aggregate into large clusters, resulting in lower bioactivity, bioavailability and biocompatibility. Surface-capping agents on SeNPs play crucial roles in its stabilization and biological activity. Here, a green synthesis method for the preparation of Lycium barbarum polysaccharides capped SeNPs using green tea extracts as reductants under mild conditions, at room temperature, is reported. The structure, size, morphology and thermal behaviour were analyzed by various characterization techniques. The functionalized nanoparticles demonstrated high antioxidant activity, including DPPH and ABTS free radical scavenging. Moreover, the SeNPs significantly protected the H₂O₂-induced PC-12 cell death. Taken together, these results evidence the possible application of these SeNPs as antioxidants food supplement or ingredient and neuroprotective agent.

Controlling Aedes albopictus and Culex pipiens pallens using silver nanoparticles synthesized from aqueous extract of Cassia fistula fruit pulp and its mode of action

Mosquitoes act as key vector for transmission of devastating parasites and pathogens which affect millions of people globally. In this research, the green synthesis of silver nanoparticles of Cassia fistula fruit pulp as an innovative and operative tool against vector mosquitoes is presented. Silver nanoparticles were characterized by a series of techniques including Fourier transform infrared spectroscopy, Transmission Electron Microscope and confirmed by Scanning Electron Microscope, UV-Vis spectrophotometry and X-ray diffraction. Silver nanoparticles were highly effective against the larvae (I-IV instar) and pupae of Aedes albopictus and Culex pipiens pallens after 24, 48 and 72 h of treatment. Ae. albopictus had LC50 values ranging from 8.3 mg/L (I instar) to 17.3 mg/L (pupae) and LC50 ranging from 1.1 mg/L (I instar) to 19.0 mg/L (pupae) against Cx. pipiens pallens. The systemic effect of AgNPs was further assessed in the fourth instar larvae of Ae. albopictus and Cx. pipiens pallens by measuring the levels of total proteins and activity of two important marker enzymes: Acetylcholinesterase and α- and β-carboxylesterase. Overall, the findings of the study suggest that the use of Cassia fistula-fruit pulp extract mediated synthesis of silver nanoparticles can be used for controlling vector mosquitoes. This is the first report on the mosquito larvicidal and pupicidal activity of AgNPs synthesized by Cassia fistula fruit pulp and its possible mechanism of action.