Using aqueous cyanobacterial extracts in the synthesis of silver nanoparticle is looked as green, ecofriendly, low priced biotechnology that gives advancement over both chemical and physical methods. In the current study, an aqueous extract of Oscillatoria limnetica fresh biomass was used for the green synthesis of Ag-NPs, since O. limnetica extract plays a dual part in both reducing and stabilizing Oscillatoria-silver nanoparticles (O-AgNPs). The UV-Visible absorption spectrum, Fourier transforms infrared (FT-IR), transmission electron microscopy (TEM) and scanning electron microscope (SEM) were achieved for confirming and characterizing the biosynthesized O-AgNPs. TEM images detected the quasi-spherical Ag-NPs shape with diverse size ranged within 3.30–17.97 nm. FT-IR analysis demonstrated the presence of free amino groups in addition to sulfur containing amino acid derivatives acting as stabilizing agents as well as the presence of either sulfur or phosphorus functional groups which possibly attaches silver. In this study, synthesized Ag-NPs exhibited strong antibacterial activity against multidrug-resistant bacteria (Escherichia coli and Bacillus cereus) as well as cytotoxic effects against both human breast (MCF-7) cell line giving IC50 (6.147 µg/ml) and human colon cancer (HCT-116) cell line giving IC50 (5.369 µg/ml). Hemolytic activity of Ag-NPs was investigated and confirmed as being non- toxic to human RBCs in low concentrations.

Background and Aim: Nanosized inorganic antibacterial materials have received increasing attention in recent years. The present study aimed to determine the antimicrobial activity of silver (Ag) and zinc oxide (ZnO) nanoparticles alone and in combination with antibiotics against reference strains of pathogenic microorganisms as Staphylococcus aureus (Staph. aureus), Salmonella enterica subsp. Bukuru, Escherichia coli (E.coli) and Candida albicans ( C. albicans). Methods: The antimicrobial effect of metal-nanoparticles (AgNPs and ZnONPS) and in combination with antibiotics was studied using the normal disc-diffusion method. Results: Both AgNPs and ZnONPs had increased antibacterial activity with an increase in their concentration against Gram-positive bacterium (Staph. aureus), Gram-negative bacteria (E. coli and Salmonella spp) and no effect on C. albicans. The synergistic effect of antibiotics (azithromycin, cefotaxime, cefuroxime, fosfomycin and chloramphenicol) against E. coli was significantly increased in the presence of AgNPs compared to antibiotic only. However, all antibiotics had a synergistic effect in the presence of AgNps against Salmonella spp. On the other hand, the antibacterial action of AgNPs with oxacillin and neomycin antibiotics against Staph. aureus was significantly decreased in comparison with antibiotics only. The synergistic effect of antibiotics (azithromycin, oxacillin, cefotaxime, cefuroxime, fosfomycin and oxytetracycline) against E. coli was significantly increased in presence of ZnONPs compared to antibiotic only and also the synergistic effect of antibiotics (azithromycin, cefotaxime, cefuroxime, fosfomycin, chloramphenicol and oxytetracycline) against Staph. aureus was significantly increased in the presence of ZnONPs compared to antibiotics only. On the other hand, most antibiotics had an antagonistic effect in presence of ZnONps against Salmonella spp. Conclusion: AgNPs and ZnONPs demonstrate a good synergistic effect with antibiotics and this may open the door for a future combination therapy against pathogenic bacteria.

Lead (Pb2+) is among the most toxic heavy metals even in low concentration and cause toxicity to human’s health and other forms of life. It is released into the environment through different industrial activities. The biosorption of Pb2+ from aqueous solutions by biomass of commonly available, marine alga Gelidium amansii was studied. The effects of different variables on Pb2+ removal were estimated by a two-level Plackett–Burman factorial design to determine the most significant variables affecting Pb2+ removal % from aqueous solutions. Initial pH, Pb2+ concentration and temperature were the most significant factors affecting Pb2+ removal chosen for further optimization using rotatable central composite design. The maximum removal percentage (100%) of Pb2+ from aqueous solution by Gelidium amansii biomass was found under the optimum conditions: initial Pb2+ concentration of 200 mg/L, temperature 45 °C, pH 4.5, Gelidium amansii biomass of 1 g/L and contact time of 60 minutes at static condition. FTIR analysis of algal biomass revealed the presence of carbonyl, methylene, phosphate, carbonate and phenolic groups, which are involved in the Pb2+ ions biosorption process. SEM analysis demonstrates the ability of Gelidium amansii biomass to adsorb and removes Pb2+ from aqueous solution. EDS analysis shows the additional optical absorption peak corresponding to the Pb2+ which confirms the involvement of Gelidium amansii biomass in the adsorption of Pb2+ ions from aqueous solution. Immobilized Gelidium amansii biomass was effective in Pb2+ removal (100%) from aqueous solution at an initial concentration of 200 mg/L for 3 h. In conclusion, it is demonstrated that the red marine alga Gelidium amansii biomass is a promising, efficient, ecofriendly, cost-effective and biodegradable biosorbent for the removal of Pb2+ from the environment and wastewater effluents.

Cadmium is a global heavy metal pollutant. Marine green algae were used as efficient, low cost and eco-friendly biosorbent for cadmium ions removal from aqueous solutions. Plackett-Burman design was applied to determine the most significant factors for maximum cadmium removal from aqueous solutions using dry Ulva fasciata biomass. The most significant factors affecting cadmium removal process were further optimized by the face centered central composite design. The results indicated that 4 g of dry Ulva fasciata biomass was found to successfully remove 99.96% of cadmium from aqueous solution under the conditions of 200 mg/L of initial cadmium concentration at pH 5, 25 °C for 60 min of contact time with static condition. Dry Ulva fasciata biomass samples before and after cadmium biosorption were analyzed using SEM, EDS and FTIR. Furthermore, the immobilized biomass in sodium alginate-beads removed 99.98% of cadmium from aqueous solution at an initial concentration of 200 mg/L after 4 h which is significantly higher than that for control using sodium alginate beads without incorporation of the algal biomass (98.19%). Dry biomass of Ulva fasciata was proven to be cost-effective and efficient to eliminate heavy metals especially cadmium from aquatic effluents and the process is feasible, reliable and eco-friendly.

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Textile wastewater contains large quantities of azo dyes mixed with various contaminants especially heavy metal ions. The discharge of effluents containing methyl orange (MO) dye and Cu2+ ions into water is harmful because they have severe toxic effects to humans and the aquatic ecosystem. The dried algal biomass was used as a sustainable, cost-effective and eco-friendly for the treatment of the textile wastewater. Box–Behnken design (BBD) was used to identify the most significant factors for achieving maximum biosorption of Cu2+ and MO from aqueous solutions using marine alga Fucus vesiculosus biomass. The experimental results indicated that 3 g/L of F. vesiculosus biomass was capable of removing 92.76% of copper and 50.27% of MO simultaneously from aqueous solution using MO (60 mg/L), copper (200 mg/L) at pH 7 within 60 min with agitation at 200 rpm. The dry biomass was also investigated using SEM, EDS, and FTIR before and after MO and copper biosorption. FTIR, EDS and SEM analyses revealed obvious changes in the characteristics of the algal biomass as a result of the biosorption process. The dry biomass of F. vesiculosus can eliminate MO and copper ions from aquatic effluents in a feasible and efficient method.

Background Root-knot nematodes are known to cause significant damage to eggplants. New approaches by green silver nanoparticles (GSN) are used to control plant-parasitic nematode to avoid chemical nematicide hazards. Objectives Analyses of the incorporation of different concentrations of nanoparticles on two different algae (Ulva lactuca and Turbinaria turbinata) were carried out. Furethermore, the effect of GSN on the eggplant DNA profile was studied using RAPD and EST molecular markers. Materials and Methods Green Silver Nanoparticles (GSN) have been synthesized and characterized using the algal extract solution prepared from two algal genera. Nematicidal effect of the GSN was evaluated in greenhouse on eggplants (Solanum melongena cv. Login). Genomic DNA was extracted for use in molecular analysis. Both RAPD and EST molecular markers were used to study the GSN effect on eggplant DNA modification. Results GSN (17 mg.mL-1) obtained from U. lactuca was more effective in reducing second-stage juveniles (J2s) of M. javanica (69.44%) population in soil. All treatments improved eggplants growth parameters. Change in DNA profile using of both RAPD and EST markers was noted. Conclusions GSN (12.75 mg.100 mL-1) were effective on controlling the root-knot nematode (both T. turbinata and U. lactuca algae), similar to chemical control in eggplants. GSN did not cause any phototoxicity in eggplants under treatment.