Assessing silver nanoparticle and antimicrobial combinations for antibacterial activity and biofilm prevention on surgical sutures.

AIMS: To evaluate the effect of silver nanoparticles alone and in combination with Triclosan, and trans-cinnamaldehyde against Staphylococcus aureus and Escherichia coli biofilms on sutures to improve patients' outcomes. METHODS AND RESULTS: Silver nanoparticles were prepared by chemical method and characterized by UV-visible spectrophotometer and dynamic light scattering. The minimum inhibitory concentration was assessed by the Microdilution assay. The antibiofilm activity was determined using crystal violet assay. A checkerboard assay using the fractional inhibitory concentration index and time-kill curve was used to investigate the synergistic effect of silver nanoparticle combinations. The hemolytic activity was determined using an erythrocyte hemolytic assay. Our results revealed that silver nanoparticles, Triclosan, and trans-cinnamaldehyde (TCA) inhibited S.aureus and E.coli biofilms. Silver nanoparticles with TCA showed a synergistic effect (FICI values 0.35 and 0.45 against S. aureus and E. coli biofilms, respectively), and silver nanoparticles with Triclosan showed complete inhibition of S. aureus biofilm. The hemolytic activity was <2.50% for the combinations.

Removal of phenolic compounds from aqueous solution using MgCl2-impregnated activated carbons derived from olive husk: the effect of chemical structures.

Activated carbon (BC) prepared from olive oil solid waste (olive husk) by slow pyrolysis was chemically activated using MgCl2 (BC-MgCl2). The BC and BC-MgCl2 were used as adsorbents for removal of three phenolic compounds, namely, phenol (P), p-methoxyphenol (PMP) and p-nitrophenol (PNP), from aqueous solution. The uptake of these three phenolic compounds by the BC and BC-MgCl2 was better expressed by the Langmuir and Dubinin-Radushkevich (D-R) isotherm models than by the Freundlich isotherm, and the kinetics of the adsorption process followed the pseudo-second order kinetic model. The maximum monolayer adsorption capacity of P, PMP and PNP were increased from 24.938, 45.455 and 61.728 on BC to 43.860, 98.039 and 121.951 mg/g on BC-MgCl2 by factors of 1.76, 2.16 and 1.98, respectively. Therefore, the chemical activation of BC by MgCl2 is indeed of importance for improving its adsorption performances. For both adsorbents, the adsorption phenomenon for different substituted phenols is a strong function of solubility, polarity, molecule structure, and size. At the tested temperatures (25, 35 and 45 °C), the negative values of ΔG° and positive values of ΔH° and ΔS° for the adsorption of P, PMP and PNP on BC and BC-MgCl2 demonstrated that the adsorption was a spontaneous, endothermic and entropy-increasing process.

Phenol adsorption on biochar prepared from the pine fruit shells: Equilibrium, kinetic and thermodynamics studies.

Biochar samples were prepared from pine fruit shell (PFS) biomass using slow pyrolysis for 1 h at three different temperatures (350, 450 and 550°C). Batch experiments were carried out for the biosorption of phenol onto these biochars. The effect of biosorption experimental parameters such as adsorbent dosage, ionic strength, initial solution pH, contact time and temperatures has been investigated. Experimental equilibrium data were fitted to Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherms by non-linear regression method. The experimental kinetic data were also fitted to Lagergren pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models by non-linear regression method. Determination coefficient (R2), chi-squared (χ2) and error function (Ferror%) were used to determine the optimum isotherm and kinetic by non-linear regression method. Kinetics results were best described by pseudo-second order model for phenol onto three biochars. Thermodynamic parameters were estimated and implied that the adsorption process is spontaneous and exothermic in nature.

Characterization of biochar prepared from slow pyrolysis of Jordanian olive oil processing solid waste and adsorption efficiency of Hg2+ ions in aqueous solutions.

Solid waste from Jordanian olive oil processing (OOSW) was used to prepare biochar samples by slow pyrolysis at terminal temperatures of 350, 450, 550 and 630 °C; henceforth known as BC-350, BC-450, BC-550 and BC-630, respectively. These samples were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction, ash content, moisture content and surface area. The ability of the biochar to remove Hg2+ ions from aqueous solutions was investigated in laboratory scale batch experiments. The kinetics, effect of pH and temperature were studied. The optimum pH value for Hg2+ adsorption was 5. Dubinin-Radushkevich (D-R) isotherm model was the best fit for the experimental results. Based on the D-R model, the maximum adsorption capacities at 25 °C were 84.93, 94.48, 96.11 and 104.59 mg.g-1, for BC-350, BC-450, BC-550 and BC-630, respectively. The pseudo-second-order kinetic model was a good fit for the experimental data. The calculated change in free energy ΔG and enthalpy ΔH indicated that the adsorption process was spontaneous and exothermic in nature. The positive value of ΔS showed increased randomness of the solid/solution interface during the adsorption. The results indicated that biochar derived from OOSW can be a good adsorbent for treatment of water contaminated with Hg2+.

The Effect of Full-Scale Exchange of Ca2+ with Zn2+ Ions on the Crystal Structure of Brushite and Its Phase Composition.

This study was carried out to investigate the effect of a complete exchange of Ca2+ with Zn2+ ions on the structure of brushite (CaHPO4·2H2O), which might be advantageous in the production process of CaxZn1-xHPO4·nH2O. To acquire the starting solutions needed for the current study, (NH4)2HPO4, Ca(NO3)2·4H2O, and Zn(NO3)2·6H2O were utilized in several molar concentrations. The findings indicate that Ca is partly substituted by Zn when the Zn/Ca molar ratio is below 0.25 and that Zn doping hinders the crystallization of brushite. A continued increase in the Zn/Ca molar ratio to 1 (at which point the supersaturation of the Zn solution rises) led to a biphasic compound of monoclinic brushite and parascholzite precipitate. Elevating the Zn/Ca molar ratio to 1.5 resulted in a precipitate of a parascholzite-like mineral. Finally, increasing the Zn/Ca molar ratio to 4 and above resulted in the formation of the hopeite mineral. Future biomaterial production with specific and bespoke characteristics can be achieved by adjusting the Zn/Ca ratio in the starting solution. It Rhas been established that the Zn/Ca ratio in the starting solution can be adjusted to obtain minerals with specific compositions. Thus, new synthesis methods for parascholzite and hopeite were introduced for the first time in this manuscript.

Fabrication of a Novel (PVDF/MWCNT/Polypyrrole) Antifouling High Flux Ultrafiltration Membrane for Crude Oil Wastewater Treatment.

The present work deals with the fabrication of novel poly(vinylidene fluoride) (PVDF)/Multi-wall Carbon Nanotubes (MWCNT)/Polypyrrole (PPy) ultrafiltration membrane by phase inversion technique for the removal of crude oil from refinery wastewater. In situ polymerization of pyrrole with different concentrations of MWCNT ranging from 0.025 wt.% to 0.3 wt.% in PVDF prepared solutions. Measurement of permeability, porosity, contact angle, tensile strength, zeta potential, rejection studies and morphological characterization by scanning electron microscopy (SEM) were conducted. The results showed that membrane with (0.05% MWCNT) concentration had the highest permeability flux (850 LMH/bar), about 17 folds improvement of permeability compared to pristine PVDF membrane. Moreover, membrane rejection of crude oil reached about 99.9%. The excellent performance of this nanocomposite membrane suggests that novel PVDF modification with polypyrrole had a considerable effect on permeability with high potential for use in the treatment of oily wastewater in the refinery industry.

Green Synthesis of Silver Nanoparticles as an Effective Antibiofouling Material for Polyvinylidene Fluoride (PVDF) Ultrafiltration Membrane.

Silver nanoparticles (AgNPs) were successfully synthesized using the aqueous extract of the Paronychia argentea Lam (P. argentea) wild plant. The results showed that the conversion of Ag+ to Ag0 nanoparticles ratio reached 96.5% as determined by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES), with a negative zeta potential (ζ) of -21.3 ± 7.68 mV of AgNPs expected to improve the stability of synthesized AgNPs. AgNP antibacterial activity has been examined against Streptococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria. The minimum inhibition concentration (MIC) was 4.9 µL/mL for both E. coli and S. aureus bacteria, while the minimum bactericidal concentrations (MBC) were 19.9 µL/mL and 4.9 µL/mL for S. aureus and E. coli, respectively. The synthesized AgNPs were incorporated in ultrafiltration polyvinylidene Fluoride (PVDF) membranes and showed remarkable antibiofouling behavior against both bacterial strains. The membranes were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and X-ray diffraction (XRD). The contact angle and porosity of the membrane were also determined. The efficiency of the membranes regarding rejection rate was assessed using bovine serum albumin (BSA). It was found in the flux experiments that membranes BSA rejection was 99.4% and 98.7% with and without AgNPs, respectively.

Decolourization of crystal violet using nano-sized novel fluorite structure Ga2Zr2-x W x O7 photocatalyst under visible light irradiation.

Fluorite-type Zr-based oxides with the composition Ga2Zr2-x W x O7 (x = 0, 0.05, 0.1, 0.15 and 0.2) were prepared using the citrate technique. Appropriate characterizations of all prepared materials were carried out. X-ray diffraction clarified that the undoped and W-doped Ga2Zr2O7 samples were crystallized in the cubic fluorite phase structure. The average particle size of the samples was in the range of 3-8 nm. The lowest band gap (1.7 eV) and the highest surface area (124.3 m2 g-1) were recorded for Ga2Zr0.85W0.15O7. The photocatalytic impacts of the prepared systems were studied by removal of crystal violet (CV) dye employing visible light illumination and taking into consideration the initial dye concentrations, duration of visible irradiation treatment, catalysts dose and the dopant concentration. The obtained results showed higher dye removal with the boost of the catalyst dosage. W doping shifted the absorption to the visible light range by decreasing the band gap from 4.95 eV for parent Ga2Zr2O7 to 1.7 eV for 15 mol% tungsten-doped Ga2Zr2O7 enhancing the photocatalytic decolourization of CV from 4.2% to 83.6% for undoped and 15 mol% W-doped Ga2Zr2O7, respectively, at optimum operating conditions (pH 9, 1 g l-1 catalyst dose and 300 min) while heavily doped W sample containing 20 mol% W showed lower removal than 15 mol% W-doped Ga2Zr2O7. Complete CV degradation using 15 mol% W-doped Ga2Zr2O7 was attained with the assistance of 25 mmol l-1 hydrogen peroxide. The reaction is aligned to pseudo-first-order kinetics. Different scavengers were introduced to decide the significance of the reactive species in CV degradation. O 2 - ∙ and h + had the major role in the degradation of CV by Ga2Zr2-x W x O7 system compared with HO•.