Synthesis and Structural Characterization of Selenium Nanoparticles-Bacillus sp. MKUST-01 Exopolysaccharide (SeNPs-EPS) Conjugate for Biomedical Applications

Development of nanocomposite-selenium filter for water disinfection and bioremediation of wastewater from Hg and AgNPs

Selenium nanoparticles (SeNPs) are used in several sectors as antitumor, antimicrobial, and environmental adsorbents. Thus, the present research objective was the production of bacterial-SeNPs as an active and environmentally-friendly antibacterial and adsorbent agents and application into novel nanocomposite filter. From a total of 25 samples (soil, wastewater, and water) obtained from different locations in Egypt, 60 selenium-resistant bacterial isolates were obtained (on a mineral salt medium supplemented with selenium ions). After screening (based on the conversion of selenium from ionic form to nanoform), a superior bacterial isolate for SeNPs formation was obtained and molecular identified as Bacillus pumilus isolate OR431753. The high yield of SeNPs was noted after optimization (glucose as carbon source, pH 9 at 30 °C). The produced SeNPs were characterized as approximately 15 nm-diameter spherical nanoparticles, in addition to the presence of organic substances around these particles like polysaccharides and aromatic amines (protein residues). Also, they have antibacterial activity increased after formation of nanocomposite with nano-chitosan (SeNPs/NCh) against several pathogens. The antibacterial activity (expressed as a diameter of the inhibitory zone) averaged between 2.1 and 4.3, 2.7 and 4.8 cm for SeNPs and SeNPs/NCh, respectively compared with 1.1 to 1.8 cm for Amoxicillin. The produced nanoselenium/chitosan was used as a biofilter to remove mercury (Hg) and AgNPs as model chemicals with serious toxicity and potential pollutant for water bodies in many industries. The new SeNPs/NCh biofilter has proven highly effective in individually removing mercury and AgNPs from their synthetic wastewaters, with an efficiency of up to 99%. Moreover, the removal efficiency of AgNPs stabilized at 99% after treating them with the syringe filter-Se nanocomposite for 4 cycles of treatment (5 min each).

Chemical modification of bacterial exopolysaccharides: Antioxidant properties and health potentials

In recent years, there has been a burgeoning interest in the utilization of microbial exopolysaccharides (EPS) because of the added advantage of their renewable, biocompatible, and biodegradable nature in addition to intended applications. The endowed properties of bacterial EPS make them valuable candidates for a wide array of industrial applications. Modification of native EPS is known to enhance various physico-chemical and functional properties. Various modifications such as physical, chemical, biological, and enzymatic modifications were practiced improving the bioactivity of EPS. This paper comprehensively aims to review the most recent chemical modification techniques employed to modify the physico-chemical and functional changes of bacterial EPS in comparison with the unmodified forms. Chemical modification entails strategic alterations to the structure and properties of EPS through various synthetic and semi-synthetic methodologies. Emphasis is given to the antioxidant potential and functional role of these EPS derivatives in human health. Antioxidant properties reveal a significant augmentation in activity compared to their native counterparts. Such enhancement holds a strong promise for potential benefits and therapeutic applications. Chemical derivatives of EPS with overwhelming functional benefits could surely encourage EPS application, particularly as potential hydrocolloids in industrial and biomedical contexts.

Green Synthesis of Selenium Nanoparticles From Clove and Their Toxicity Effect and Anti-angiogenic, Antibacterial and Antioxidant Potential

Introduction  Nanoparticles, owing to their minuscule size, have become pivotal in diverse scientific endeavors, presenting unique characteristics with applications spanning medicine to environmental science. Selenium nanoparticles (SeNPs) exhibit potential in diverse biomedical uses. Aim This research investigates the potential anti-inflammatory and anticancer properties of SeNPs, which are synthesized using the green synthesis method. This eco-friendly approach aligns with sustainable practices and utilizes clove extract (Syzygium aromaticum). Materials and methods Clove extract facilitates SeNP synthesis via sodium selenite reduction. The characterization methods comprised Fourier-transform infrared (FTIR) spectroscopy, UV-VIS spectroscopy, and scanning electron microscopy (SEM). Assessments covered antioxidant properties, chorioallantoic membrane assay (CAM) assay for antiangiogenic effects, toxicity evaluation, and antibacterial assays. Results Successful synthesis of SeNPs was verified by a UV-visible absorption peak at 256 nm and FTIR peaks around 3500-500 cm -1, and the spherical morphology was confirmed by SEM analysis with EDAX, which indicated the presence of SeNPs and their unique properties. Phytochemical substances are active chemicals that contribute to the properties of SeNPs. The SeNPs exhibited antioxidant activity with an IC50 value of 0.437 µg/mL and antibacterial properties against bacterial pathogen Salmonella species, with a zone of inhibition measuring 19 mm. The CAM assay demonstrated possible antiangiogenic actions, and toxicity testing on Artemia nauplii showed biocompatibility. Conclusion This study underscores the efficient synthesis of SeNPs using clove extract, emphasizing their potential applications. The notable properties of SeNPs emphasize their promise for diverse biomedical and environmental uses.