Magnetic chitosan/calcium alginate double-network hydrogel beads: Preparation, adsorption of anionic and cationic surfactants, and reuse in the removal of methylene blue.

Robust and reusable magnetic chitosan/calcium alginate double-network hydrogel beads (CSMAB) with an environmentally benign biocomposite material synthesis approach were used adsorption of surfactant and removal of methylene blue dye sequentially for the first time. Double network hydrogel structure with sodium alginate and chitosan and acidification of the surface with HCl provided the reusability of the beads at the pollutant removal in water. The CSMAB beads were characterized for structural analysis by FESEM, EDX, BET, VSM, and FTIR techniques. They were used for the adsorption of cationic hexadecylpyridinium chloride (HDPCl) and anionic sodium dodecyl sulfate (SDS) surfactants and reused in the removal of cationic methylene blue dye without any pretreatment. The effect of pH, adsorbent dose, and temperature on surfactant removal efficiency was analyzed and pH was found the statistical significance. The adsorption capacity of CSMAB beads with a surface area of 0.65 m2 g-1 was calculated as 1.9 mg g-1 for HDPCl, and 1.2 mg g-1 for SDS, respectively. The SDS and HDPCl adsorption followed the pseudo-second-order kinetic and Freundlich isotherm model. The thermodynamic results showed that the surfactant adsorption process is an exothermic and spontaneous process. SDS-reacted CSMAB beads showed higher efficiency with 61 % in the removal of methylene blue dye.

Green Synthesis of Gold Nanoflowers Using Rosmarinus officinalis and Helichrysum italicum Extracts: Comparative Studies of Their Antimicrobial and Antibiofilm Activities.

This study was concerned with the green synthesis of gold nanoflowers (AuNFs) using the bioactive constituents of Rosmarinus officinalis (rosemary) and Helichrysum italicum (immortelle) extracts, as reducer and stabilizer agents along with the determination of their antibacterial and antibiofilm activity against E. coli, S. aureus, and S. epidermidis. The AuNFs were characterized using STEM, UV-Vis, DLS, ZETA, FESEM-EDX, and FTIR techniques. The antibacterial and antibiofilm activity of the AuNFs were evaluated by microdilution broth and microtiter plate (MTP) tests, respectively. STEM and DLS analysis confirmed the flower-like morphology of gold nanoparticle clusters of R. officinalis-AuNFs (R-AuNFs) and H. italicum-AuNFs (H-AuNFs) with a size of 20-130 nm and 15-90 nm, respectively. The MICs of R-AuNFs were found to be 40 µg/mL for E. coli and S. epidermidis and 160 µg/mL for S. aureus. The MICs of H-AuNFs against all bacterial strains were 20 µg/mL. All tested AuNFs exhibited a strong dose-dependent antibiofilm activity against the test strains, and H-AuNFs was more effective than R-AuNFs. The green synthesis of AuNFs from the rosemary and immortelle extracts can be applied as a potential agent to overcome the growth of biofilm-producing microorganisms in food industries.

Peroxidase-like activity and antimicrobial properties of curcumin-inorganic hybrid nanostructure.

For the first time in this study, curcumin was utilized as an organic component reacting with Cu (II) ion (Cu2+) as an inorganic component for fabrication of curcumin based Cu hybrid nanostructure (Cu-hNs). We also systematically examined the catalytic effect towards guaiacol and antimicrobial activities of Cu-hNs towards fish pathogen bacteria. For the characterization of Cu-hNs, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectrometry (FT-IR) analysis were used. We claimed that hydroxyl group might react with Cu2+ in phosphate solution (PO4 -3) to form Cu-hNs. However, more uniform and spherical Cu-hNs were not seen owing to absence of more reactive functional groups like amine and carboxyl groups on structure of curcumin. In addition to our findings, synthesis of Cu-hNs were carried out in the various pH values to evaluate the effect of pHs on formation of Cu-hNs. The Cu-hNs exhibited remarkable catalytic activity throught the Fenton reaction in the presence of hydrogen peroxide (H2O2) and effective antimicrobial activities against Gram-positive/negative fish pathogen bacteria. In this study, cheap and efficient synthesis of nanoflowers (NFs) using plant extracts is proposed for biomedical applications rather than expensive molecules such as amino acids and DNA.

Green synthesis of allicin based hybrid nanoflowers with evaluation of their catalytic and antimicrobial activities.

OBJECTIVE: Although organic-inorganic hybrid nanoflowers (hNFs) with much enhanced catalytic activity and stability were fabricated using proteins and enzymes, in this study, for the first time, we report synthesis of allicin and copper ion (Cu2+) coordinated NFs and investigate their peroxidase-like and antimicrobial activities. RESULTS: The allicin (active ingredient of Allium sativum) and Cu2+ was acted as an organic and inorganic part, respectively for synthesis of the Cu-hNFs. The hNFs were characterized by various techniques. Spherical, uniform, mono-dispersed and flower-like-shaped morphology of the hNFs (synthesized at pH 5) were imaged by scanning electron microscopy. The presence of Cu metal in the hNFs was detected by energy dispersive X-ray spectroscopy. Characteristic bonds stretching and bending for structural analysis of the hNFs were carried out by Fourier transform infrared spectrometry. In terms of applications, the hNFs showed quite effective peroxidase-like activity towards to guaiacol (used as a model substrate) in the presence of hydrogen peroxide (H2O2) through Fenton reaction. We demonstrated that the NFs exhibited ~ 200% and ~ 500% higher catalytic activities in 1 h (hr) and 3 h (hrs) than their initial catalytic activity measured in 5 minute (min). Additionally, effective antibacterial properties of the Cu-hNFs were observed against fish pathogen bacteria (Aeromonas hydrophila, Vibrio parahaemolyticus, and Lactococcus garvieae). CONCLUSIONS: We finally demonsrated that allicin based hybrid nanomaterial can be prepared by a relatively cheap, one step, easy and eco-friendly method. The allicin hNFs can be considered as novel Fenton agent for peroxidase like activity and bactericidal.

Green synthesis and characterization of iron oxide nanoparticles using Ficus carica (common fig) dried fruit extract.

Ficus carica (common fig) dried fruit extract was used to synthesize iron oxide nanoparticles in this study. Biomaterials in the common fig dried fruit extract synthesized the iron nanoparticles by reducing the iron precursor salt and then acted as capping and stabilizing agents. The nanoparticles were produced smaller than 20 nm diameters and oxidized due to the high phenolic compound content in the common fig dried fruit extract. Nanoparticles were characterized by energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), UV-visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS). First, color change and pH reduction occurred immediately due to the iron nanoparticle synthesis. TEM images showed that the nanoparticles were at 9 ± 4 nm diameters and the metallic core-oxide shell form. The nanoparticles were in spherical shapes with a monodisperse distribution. EDX, XRD and FTIR analysis signals showed the iron oxyhydroxide/oxide formation. Absorption peaks were detected at 205 nm and 291 nm due to the iron metallic core hydrolysis products. The intensity-average diameter of nanoparticles was calculated at 475 nm diameter by DLS analysis. Colloid stability was determined as moderate at 20.7 mV.

Ecophysiological tolerance of Lemna gibba L. exposed to cadmium.

In this study, an experiment was carried out to study the process of stress adaptation in Lemna gibba L. grown under cadmium stress (0-20mg Cd L(-1)). The level of photosynthetic pigments and soluble proteins decreased only upon exposure to high Cd concentrations (for pigments 5mg Cd L(-1); for soluble proteins 10mg Cd L(-1)). At the same time, the level of malondialdehyde (MDA) increased with increasing Cd concentration. These results suggested an alleviation of stress that was presumably the result of antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione S-transferase (GST) as well as ascorbate peroxidase (APX), which increased linearly with increasing Cd levels. In addition, the proline content in L. gibba increased with increasing cadmium levels. These findings suggest that Lemna is equipped with an efficient antioxidant mechanism against Cd induced oxidative stress which protects the plant's photosynthetic machinery from damage.We also found that moderate Cd treatment (0.05-5mg L(-1) Cd) alleviated oxidative stress in plants, while the addition of higher amounts of Cd (10-20mg L(-1)) could cause an increasing generation of ROS, which was effectively scavenged by the antioxidative system.

Response of antioxidant defences to Zn stress in three duckweed species.

In the plants, Lemna gibba, Lemna minor and Spirodela polyrrhiza L., the effect of different concentrations of zinc (0.01, 0.05, 0.1, 0.5 and 1.5mgL(-1) Zn) applied for four day was assessed by measuring changes in the chlorophyll, protein, malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX) and guiacolperoxidase (GPX) activity of the plants. According to results, Zn contents in plants increased with increasing Zn supply levels. The level of photosynthetic pigments and soluble proteins reduced only upon exposure to high Zn concentrations. At the same time, the level of malondialdehyde (MDA) increased with increasing Zn concentration. These results suggested an alleviation of stress that was possibly the result of antioxidants such as catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX) as well as guaiacol peroxidise (GPOX), which increased linearly with increasing Zn levels. Cellular antioxidant levels showed an increase suggesting a defensive mechanism to preserve against oxidative stress given rise to by Zn. Besides, the proline amount in L. gibba, L. minor and S. polyrrhiza increased with increasing zinc levels. These conclusions proposed that L. gibba, L. minor and S. polyrrhiza are supplied with an efficient antioxidant mechanism against Zn-induced oxidative stress which saves the plant's photosynthetic machinery from damage. It is concluded that higher zinc levels cause oxidative stress in L. gibba, L. minor and S. polyrrhiza cells and may reason membrane damage through production of ROS and interferes with chlorophyll metabolism.

Effect of circulation on wastewater treatment by Lemna gibba and Lemna minor (floating aquatic macrophytes).

In this study, laboratory tests were performed in order to examine growth characteristics of floating aquatic macrophytes (Lemna gibba and Lemna minor) in the presence of wastewater with circulation. The results showed that circulation of the waste water enhanced the kinetics of the process, as compared to the control systems. However, prolonged application of high circulation level had a different effect. In the presence of circulation with aquatic plants, there was additional 85.3-88.2% for BODs and 59.6-66.8% for COD decreases in the water quality indicators. In this study, the effectiveness of L. gibba and L. minor with circulation addition for the removal of four heavy metals (Pb, Ni, Mn, and Cu) from waste water was also investigated. Results from analysis confirmed the accumulation of different metals within the plant and a corresponding decrease of metals in the waste water. At the end of the study of circulation, L. gibba provided the metal removal for Cu, Pb, Ni, and Mn in the waste water as the ratio of 57%, 60%, 60%, and 62%, respectively. In this context, the best results were obtained when the action of L. gibba and L. minor plants, was combined with that of circulation. It is shown that in the presence of L. gibba and L. minor plants that are supplemented with circulation, the national standards of biochemical oxygen demand (BOD5) 27-33 mgL(-1) and chemical oxygen demand (COD) 62-78 mgL(-1) for L. minor and L. gibba, respectively, were reached after treatment. The new results can be used for design calculations regarding expected removal of pollutants by aquatic floating plants.