Expression of Concern: Statistical optimization of photo-induced biofabrication of silver nanoparticles using the cell extract of Oscillatoria limnetica: insight on characterization and antioxidant potentiality.

Expression of Concern for 'Statistical optimization of photo-induced biofabrication of silver nanoparticles using the cell extract of Oscillatoria limnetica: insight on characterization and antioxidant potentiality' by Rasha A. Abo-Elmagd et al., RSC Adv., 2020, 10, 44232-44246, DOI: https://doi.org/10.1039/D0RA08206F.

Phycotoxicity and catalytic reduction activity of green synthesized Oscillatoria gelatin-capped silver nanoparticles.

Over the last decade, an extensive range of consumer products containing manufactured silver nanoparticles (AgNPs) have been progressively used. The unfitting usage and discharge of these materials can enable passage of AgNPs into the aquatic ecosystem causing prospective toxicological consequence. The present study shed new lights on the phycotoxicity of small (8.47-17.66 nm) and stable Oscillatoria reduced gelatin-capped silver nanoparticles (OG-AgNPs) fabricated using a completely green synthetic technique. In this work, estimating of the possible toxic effects of OG-AgNPs on two freshwater microalgae Chlorella vulgaris and Chlorella minutissima was carried. This study found that, the growth of cells and photosynthetic pigment inhibitory effects of OG-AgNPs exhibit a significant increase with increasing time and concentration compared to control. Based on the IC50 value C. vulgaris (3.705 µg/mL) was found to be more sensitive to OG-AgNPs than C. minutissima (5.8 µg/mL). This study revealed that OG-AgNPs exhibit potent phycotoxic effect against Chlorella species. Finally, the negative effect of OG-AgNPs on aquatic algae and these modifications might have severe effects on structure and function of aquatic ecosystems. Besides, the biosynthesized OG-AgNPs showed a catalytic activity in the reduction of hydrogen peroxide, one of the reactive oxygen species that represent a major threat to biological systems. This method pretends an auspicious non-skill dependent technique with a good sensitivity for determination of H2O2 concentration, particularly at trace ppm level for applying in numerous domains such as medical and industrial processes.

Promoting Effect of Soluble Polysaccharides Extracted from Ulva spp. on Zea mays L. Growth.

Seaweeds can play a vital role in plant growth promotion. Two concentrations (5 and 10 mg/mL) of soluble polysaccharides extracted from the green macroalgae Ulva fasciata and Ulva lactuca were tested on Zea mays L. The carbohydrate and protein contents, and antioxidant activities (phenols, ascorbic, peroxidase, and catalase) were measured, as well as the protein banding patterns. The soluble polysaccharides at 5 mg/mL had the greatest effect on the base of all of the parameters. The highest effects of soluble polysaccharides on the Zea mays were 38.453, 96.76, 4, 835, 1.658, 7.462, and 38615.19, mg/mL for carbohydrates, proteins, phenol, µg ascorbic/mL, mg peroxidase/g dry tissue, and units/g tissue of catalase, respectively. The total number of protein bands (as determined by SDS PAGE) was not changed, but the density of the bands was correlated to the treatments. The highest band density and promoting effect were correlated to 5 mg/mL soluble polysaccharide treatments extracted from Ulva fasciata in Zea mays, which can be used as a biofertilizer.

Characterization of alginate extracted from Sargassum latifolium and its use in Chlorella vulgaris growth promotion and riboflavin drug delivery.

Alginates derived from macroalgae have been widely used in a variety of applications due to their stability, biodegradability and biocompatibility. Alginate was extracted from Egyptian Sargassum latifolium thallus yielding 17.5% w/w. The chemical composition of S. latifolium is rich in total sugars (41.08%) and uronic acids (47.4%); while, proteins, lipids and sulfates contents are 4.61, 1.13 and 0.09%, respectively. NMR, FTIR and TGA analyses were also performed. Crystallinity index (0.334) indicates alginate semicrystalline nature. Sodium alginate hydrolysate was evaluated as Chlorella vulgaris growth promoter. The highest stimulation (0.7 g/L biomass) was achieved by using 0.3 g/L alginate hydrolysate supplementation. The highest total soluble proteins and total carbohydrates were 179.22 mg/g dry wt and 620.33 mg/g dry wt, respectively. The highest total phenolics content (27.697 mg/g dry wt.), guaiacol peroxidase activity (2.899 µmol min-1 g-1) were recorded also to 0.3 g/L alginate hydrolysate supplementation. Riboflavin-entrapped barium alginate-Arabic gum polymeric matrix (beads) was formulated to achieve 89.15% optimum drug entrapment efficiency (EE%). All formulations exhibited prolonged riboflavin release over 120 min in simulated gastric fluid, followed Higuchi model (R2 = 0.962-0.887) and Korsmeyer-Peppas model with Fickian release (n ranges from 0.204 to 0.3885).

Production, extraction and characterization of Chlorella vulgaris soluble polysaccharides and their applications in AgNPs biosynthesis and biostimulation of plant growth.

Chlorella vulgaris, like a wide range of other microalgae, are able to grow mixotrophically. This maximizes its growth and production of polysaccharides (PS). The extracted polysaccharides have a complex monosaccharide composition (fructose, maltose, lactose and glucose), sulphate (210.65 ± 10.5 mg g-1 PS), uronic acids (171.97 ± 5.7 mg g-1 PS), total protein content (32.99 ± 2.1 mg g-1 PS), and total carbohydrate (495.44 ± 8.4 mg g-1 PS). Fourier Transform infrared spectroscopy (FT-IR) analysis of the extracted polysaccharides showed the presence of N-H, O-H, C-H, -CH3, >CH2, COO-1, S=O and the C=O functional groups. UV-Visible spectral analysis shows the presence of proteins, nucleic acids and chemical groups (ester, carbonyl, carboxyl and amine). Purified polysaccharides were light green in color and in a form of odorless powder. It was soluble in water but insoluble in other organic solvents. Thermogravimetric analysis demonstrates that Chlorella vulgaris soluble polysaccharide is thermostable until 240°C and degradation occurs in three distinct phases. Differential scanning calorimetry (DSC) analysis showed the characteristic exothermic transition of Chlorella vulgaris soluble polysaccharides with crystallization temperature peaks at 144.1°C, 162.3°C and 227.7°C. The X-ray diffractogram illustrated the semicrystalline nature of these polysaccharides. Silver nanoparticles (AgNPs) had been biosynthesized using a solution of Chlorella vulgaris soluble polysaccharides. The pale green color solution of soluble polysaccharides was turned brown when it was incubated for 24 hours with 100 mM silver nitrate in the dark, it showed peak maximum located at 430 nm. FT-IR analysis for the biosynthesized AgNPs reported the presence of carbonyl, -CH3, >CH2, C-H,-OH and -NH functional groups. Scanning and transmission electron microscopy show that AgNPs have spherical shape with an average particle size of 5.76. Energy-dispersive X-ray (EDX) analysis showed the dominance of silver. The biosynthesized silver nanoparticles were tested for its antimicrobial activity and have positive effects against Bacillus sp., Erwinia sp., Candida sp. Priming seeds of Triticum vulgare and Phaseolus vulgaris with polysaccharides solutions (3 and 5 mg mL-1) resulted in significant enhancement of seedling growth. Increased root length, leaf area, shoot length, photosynthetic pigments, protein content, carbohydrate content, fresh and dry biomass were observed, in addition these growth increments may be attributed to the increase of antioxidant activities.

Statistical optimization of photo-induced biofabrication of silver nanoparticles using the cell extract of Oscillatoria limnetica: insight on characterization and antioxidant potentiality.

Silver nanoparticles were successfully fabricated through a very simple, rapid, one-step photo-induced green approach. The formation of silver nanoparticles was accomplished using the bioactive compounds in the aqueous extract of fresh Oscillatoria limnetica biomass, which acted as a reducing and capping agent at the same time. The biosynthesis of Oscillatoria-silver nanoparticles (O-AgNPs) was investigated under the influence of different light intensities 57.75, 75.90 and 1276.51 µmol m-2 s-1 (bright sunlight). UV-Vis (UV) and Fourier transform infrared (FT-IR) spectroscopy were applied to approve the synthesis of AgNPs. Further, the synthesis process under the exposure to sunlight was adjusted via utilizing one factor at a time, and 0.5 mM AgNO3 concentration, 5 mL O. limnetica solution, pH 6.7 and 30 min sunlight (1276.51 µmol m-2 s-1) were applied. Furthermore, the central composite design (CCD) was applied to boost the biosynthesis process of O-AgNPs (manufactured at light intensity 75.90 µmol m-2 s-1). The maximum production of O-AgNPs was attained with 4 detected variables: initial pH level (6.7), AgNO3 concentration (0.3 mM), O. limnetica extract concentration (3.50 mL) and incubation time (48 h). Moreover, TEM, in addition to SEM, images exposed that the biosynthesized AgNPs were quasi-spherical in shape with a small monodisperse nature, and the size range was between 6.98-23.48 nm in the case of light-induced synthesis (75.90 µmol m-2 s-1) and 11.58-22.31 nm with sunlight (1276.51 µmol m-2 s-1).

Characterization and chromium biosorption potential of extruded polymeric substances from Synechococcus mundulus induced by acute dose of gamma irradiation.

This study characterized the extruded polymeric substances (EPS) secreted from Synechococcus mundulus cultures under the effect of 2-KGy gamma irradiation dose. The EPS demonstrated seven monosaccharides, two uronic acids and several chemical functional groups: O-H, N-H, =C-H, C=C, C=O, COO-, O-SO3, C-O-C and a newly formed peak at 1593 cm-1 (secondary imide). The roughness of EPS was 96.71 nm and only 28.4% total loss in weight was observed at 800 °C with a high degree of crystallinity quantified as CIDSC (0.722) and CIXRD (0.718). Preliminary comparative analyses of EPS exhibited high protein content in the radiologically modified (R-EPS) than control (C-EPS). Modified EPS were characterized with a high biosorption efficiency, which could be attributed to its high content of uronic acids, protein and sulphates as well as various saccharide monomers. Data revealed that 0.0213 mg L-1 h-1 is the maximum biosorption rate (SBRmax) of Cr(VI) for R-EPS, whereas 0.0204 mg L-1 h-1 SBRmax for the C-EPS respectively.

Synthesis and biological characterization of silver nanoparticles derived from the cyanobacterium Oscillatoria limnetica.

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.

Phycobiliprotein-mediated synthesis of biogenic silver nanoparticles, characterization, in vitro and in vivo assessment of anticancer activities.

Phycoerythrin is the main phycobiliprotein that responsible for harvesting light for photosynthesis in cyanobacteria. In this research, phycoerythrin extracted from the cyanobacterium Nostoc carneum has been used to reduce silver nitrate for silver nanoparticles (AgNPs) biosynthesis. UV-visible spectrophotometry for measuring surface plasmon resonance showed a single absorption peak at 430 nm, which confirmed the presence of AgNPs. The face-centered central composite design was chosen to evaluate the interaction effects between four process variables and also to determine their optimal levels which influence the AgNPs biosynthesis using phycoerythrin. The maximum silver nanoparticles biosynthesis (1733.260 ± 21 µg/mL) was achieved in the central runs under the conditions of initial pH 10, incubation period of the 24 h, phycoerythrin concentration of the 0.8 mg/mL and 20 mM of AgNO3. The biosynthesized AgNPs were characterized using TEM which revealed the formation of spherical shape nanoparticles with size ranged between 7.1‒26.68 nm. EDX analysis confirmed silver as the major constituent element. FTIR spectrum indicates the presence of proteinaceous capping agent that prevents silver nanoparticles agglomeration. The IC50 of cell inhibition by AgNPs was observed at 13.07 ± 1.1 µg/mL. Treatment of mice bearing Ehrlich ascites carcinoma with 5 mg AgNPs/kg of mice body weight significantly decreased tumor volume, tumor cells count, white blood cells count and body weight. It was concluded that the phycoerythrin protein has the ability to synthesize AgNPs, which have antibacterial, antihemolytic, in vitro and in vivo cytotoxic activities.

Bio-fabrication of silver nanoparticles by phycocyanin, characterization, in vitro anticancer activity against breast cancer cell line and in vivo cytotxicity.

In recent decades, researchers were attracted towards cyanobacterial components which are potential low-cost biological reagents for silver nanoparticle biosynthesis. This article describes the biological synthesis of silver nanoparticles using a proteinaceous pigment phycocyanin extracted from Nostoc linckia as reducing agent. The synthesized silver nanoparticles have a surface plasmon resonance band centered at 425 nm. Face-centered central composite design used for optimization of silver nanoparticles (AgNPs) biosynthesis using phycocyanin. The maximum AgNPs biosynthesis obtained using the optimized four variables, initial pH level (10), AgNO3 concentration (5 mM), phycocyanin pigment concentration (1 mg/mL) and incubation period (24 h) was 1100.025 µg/mL. The TEM analysis of AgNPs showed spherical nanoparticles with mean size between 9.39 to 25.89 nm. FTIR spectra showed major peaks of proteins involved in AgNPs biosynthesis by identifying different functional groups involved in effective capping of AgNPs. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic Gram-positive (Staphylococcus aureus), Gram-negative bacteria (Pseudomonas aeruginosa, E. coli and Klebsiella pneumonia). The synthesized AgNPs exhibited effective cytotoxic activity against MCF-7 and the inhibitory concentration (IC50) was recorded at 27.79 ± 2.3 µg/mL. The in vivo studies clearly indicated that AgNPs has a capacity to inhibit the growth of tumor in Ehrlich ascites carcinoma bearing mice.