Iron-based phosphorus chelator: Risk of iron deposition and action on bone metabolism in uremic rats.

Phosphate chelators are frequently used in patients with chronic kidney disease (CKD). New iron-based chelators remain understudied and offer a promising therapeutic option for the control of bone and mineral disorders of chronic kidney disease (BMD-CKD). We assessed the effect of the phosphorus chelator, chitosan-iron III (CH-FeCl), compared to calcium carbonate (CaCO3) in BMD-CKD and the potential iron overload in uremic rats. Thirty-two animals were divided into four groups, namely the control, CKD, CKD/CH-FeCl, and CKD/CaCO3 groups. CKD was induced by adding 0.75% (4 weeks) and 0.1% (3 weeks) adenine to the diet. The chelators were administered from week 3 through week 7. The renal function, BMD-CKD markers, and histomorphometry of the femur were assessed at week 7. The CKD group showed a significant increase in creatinine (83.9 ± 18.6 vs. 41.5 ± 22.1 µmol/L; P = 0.001), phosphate (3.5 ± 0.8 vs. 2.2 ± 0.2 mmol/L; P = 0.001), fractional excretion of phosphorus (FEP) (0.71 ± 0.2 vs. 0.2 ± 0.17; P = 0.0001), and FGF23 (81.36 ± 37.16 pg/mL vs. 7.42 ± 1.96; P = 0.011) compared to the control group. There was no accumulation of serum or bone iron after the use of CH-FeCl. The use of chelators reduced the FEP (control: 0.71 ± 0.20; CKD/CH-FeCl: 0.40 ± 0.16; CKD/CaCO3 0.34 ± 0.15; P = 0.001), without changes in the serum FGF23 and parathyroid hormone levels. Histomorphometry revealed the presence of bone disease with high remodeling in the uremic animals without changes with the use of chelators. The CH-FeCl chelator was efficient in reducing the FEP without iron accumulation, thereby paving the way for the use of this class of chelators in clinical settings in the future.

Eugenia umbelliflora mediated reduction of silver nanoparticles incorporated into O-carboxymethylchitosan/y-Fe2O3: Synthesis, antimicrobial activity and toxicity.

The purpose of this study was to synthesize a new magnetic material with antimicrobial properties, incorporated into a biopolymer and containing silver nanoparticles (Ag NP) prepared extract of Eugenia umbelliflora as a reducing agent. Silver nanoparticles incorporated into magnetic nanocomposite O-carboxymethylchitosan/y-Fe2O3/Ag0 (CMAgE) composite were synthesized using an extract of E. umbelliflora. The antimicrobial activity of the pathogenic microorganism is reported here. The synthesized nanoparticles were also characterized, and quantified by Ag analysis. The minimum inhibitory concentrations (MIC) of CMAgE against Staphylococcus aureus, Escherichia coli, and Candida albicans were 16.5, 1000 and 500 µg/mL, respectively. The results show that these materials have significant synergistic effect on each other. The potential phytotoxic effect of the nanocomposites was evaluated using Cucumis sativus seeds. The positive values for seedling elongation inhibition (SEI) show that CMAgE and methanol extract of Eugenia umbelliflora (Eug) cause growth inhibition at a concentration of 1000 mg/L. The germination index (GI) values of 40% and 80% at 1000 mg/L, for CMAgE and Eug, respectively, showed inhibition of germination. CMAgE and Eug showed cytotoxic effects against Artemia salina nauplii, with LC50 values of 72.5 µL/mL and < 5.0 µL/mL respectively, after 48 h.

Nanoecotoxicology study of the response of magnetic O-Carboxymethylchitosan loaded silver nanoparticles on Artemia salina.

Magnetic silver nanoparticles (MNPAg) are interesting nanotechnology materials with borderless environmental science, that can be used to disinfect water contaminated with pathogenic bacteria. The use of MNPAg leads to increased risk of nanomaterial contamination in the environment, especially natural water sources, with harmful effects on the ecosystem. This study investigating survival and enzyme activity of magnetic O-carboxymethylchitosan loaded silver nanoparticle on Artemia salina. The results showed that mortality increased with increasing concentrations of MNPAg. O-Carboxymethylchitosan loaded silver nanoparticles were found to be more toxic, with a LC50 of 902.1 mg/L for γ-Fe2O3/Ag without reducing agent. Accumulation of silver on Artemia salina depends on the type of nanoparticle. Accumulation of nanoparticle containing polymers (carboxymethylchitosan/γ-Fe2O3/Ag without reducing agent, carboxymethylchitosan/γ-Fe2O3/Ag reduced with sucrose and carboxymethylchitosan/γ-Fe2O3/Ag reduced with NaBH4) were found to be higher than γ-Fe2O3/Ag reduced with NaBH4, γ-Fe2O3/Ag reduced with sucrose and γ-Fe2O3/Ag without reducing agent under the same experimental conditions. The antioxidant enzyme (CAT, SOD and GST) activities increased slightly following exposure, indicating that the toxic effects are related to oxidative stress. The combined results so far indicate that MNPA does not have the potential to affect aquatic organisms when released into the ecosystem.

Use of chemically activated termite feces a low-cost adsorbent for the adsorption of norfloxacin from aqueous solution.

Antibiotics, as emerging contaminants, are of global concern due to the development of antibiotic resistant microorganisms. Current wastewater treatment technology cannot efficiently remove sewage antibiotics and therefore new low-cost technologies are needed. Adsorption is a widely used process for removal of substances, and the search for efficient, low-cost adsorbents is ongoing. In this work, termite feces treated with H2SO4 (FT/H2SO4) were used as a low-cost adsorbent for removal of norfloxacin (NOR) present in aqueous medium. Termite feces were treated with H2SO4 at a ratio of 1:1 for 24 h, at 100 °C. The parameters contact time, initial NOR concentration, medium pH and temperature were evaluated. The optimum adsorption pH was 8.0. The pseudo-second-order model was found to best represent the kinetics of NOR adsorption. The maximum adsorption capacity, calculated from the Sips isotherm model, was 104.4 mg/g at 55 °C. The positive values of ΔH0 (change in enthalpy) confirm the endothermic nature of the adsorption. The results show that FT/H2SO4 is an efficient adsorbent for removal of NOR present in aqueous medium. The adsorption capacity is higher than those reported in the literature for other low-cost adsorbents.

Synthesis of Ag@Fe2O3 nanocomposite based on O-carboxymethylchitosan with antimicrobial activity.

In this paper, nano-hybrid particles of Ag@Fe2O3 based on O-carboxymethylchitosan were successfully synthesized using different reducing agents (NaBH4, sucrose) and without reducing agent. The smallest silver nanoparticles were those prepared without reducing agent (∼5±3nm). The average size of silver particles prepared with NaBH4 is around 5-15nm, and for samples prepared with sucrose, the average particle size is 10-25nm. The magnetization curves are roughly reversible, indicating that γ-Fe2O3 nanoparticles transit to a superparamagnetic state. Nanocomposites subjected to antimicrobial tests showed great antimicrobial activity against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria, and good activity against the yeast Candida albicans and resistant strains of Staphylococcus aureus. The antibacterial behavior as a function of time was investigated in microbial growth kinetics, and the best nanocomposite was the one without reducing agent, which completely inhibited microbial growth for 48h.

Chitosan-Fe (III) Complex as a Phosphate Chelator in Uraemic Rats: A Novel Treatment Option.

Phosphate retention and hyperphosphataemia are associated with increased mortality in patients with chronic kidney disease (CKD). We tested the use of cross-linked iron chitosan III (CH-FeCl) as a potential phosphate chelator in rats with CKD. We evaluated 96 animals, divided equally into four groups (control, CKD, CH-FeCl and CKD/CH-FeCl), over 7 weeks. We induced CKD by feeding animals an adenine-enriched diet (0.75% in the first 4 weeks and 0.1% in the following 3 weeks). We administered 30 mg/kg daily of the test polymer, by gavage, from the third week until the end of the study. All animals received a diet supplemented with 1% phosphorus. Uraemia was confirmed by the increase in serum creatinine in week 4 (36.24 ± 18.56 versus 144.98 ± 22.1 µmol/L; p = 0.0001) and week 7 (41.55 ± 22.1 versus 83.98 ± 18.56 µmol/L; p = 0.001) in CKD animals. Rats from the CKD group treated with CH-FeCl had a 54.5% reduction in serum phosphate (6.10 ± 2.23 versus 2.78 ± 0.55 mmol/L) compared to a reduction of 25.6% in the untreated CKD group (4.75 ± 1.45 versus 3.52 ± 0.74 mmol/L, p = 0.021), between week 4 and week 7. At week 7, renal function in both CKD groups was similar (serum creatinine: 83.98 ± 18.56 versus 83.10 ± 23.87 µmol/L, p = 0.888); however, the CH-FeCl-treated rats had a reduction in phosphate overload measured by fractional phosphate excretion (FEPi) (0.71 ± 0.2 versus 0.4 ± 0.16, p = 0.006) compared to the untreated CKD group. Our study demonstrated that CH-FeCl had an efficient chelating action on phosphate.

Adsorption of hexavalent chromium by crosslinked chitosan-iron(III) in an air-lift reactor.

Column experiments were conducted in an airlift reactor containing a certain amount of crosslinked chitosan-iron(III) (Ch-Fe), to examine the effects of adsorbent mass, flow rate, and influent concentrations on Cr(VI) removal. The breakthrough time increased with an increase in Ch-Fe mass, but decreased with an increase in initial Cr(VI) concentration. The exhaustion time decreased with an increase in initial Cr(VI) concentration. The capacity at the breakthrough point increased with an increase in Ch-Fe mass, flow rate, and initial Cr(VI) concentration. The capacity at the exhaustion point increased with an increase in flow rate, but showed no specific trend with an increase in initial Cr(VI) concentration. The bed volumes at breakthrough point increased with an increase in Ch-Fe, flow rate and Cr(VI) concentration. The adsorbent exhaustion decreased with an increase in flow rate and Ch-Fe, but increased with an increase in initial Cr(VI) concentration. Columns with large amounts of Ch-Fe are preferable for obtaining optimal results during the adsorption process. The higher the flow velocity, the better the column performance. The Thomas, Clark and Yoon-Nelson models were applied to the experimental results. Good agreement was observed between the predicted theoretical breakthrough curves and the experimental results.

A magnetic nanogel based on O-carboxymethylchitosan for antitumor drug delivery: synthesis, characterization and in vitro drug release.

This paper studied the synthesis, characterization and use of the magnetic chitosan nanogel for carrying meleimidic compounds. The hydrogel polymer was prepared using O-carboxymethylchitosan, which was crosslinked with epichlorohydrin for subsequent incorporation of iron oxide magnetic nanoparticles. The characterization revealed that the magnetic material comprises about 10% of the hydrogel. This material is comprised of magnetite and maghemite and exhibits ferro-ferrimagnetic behavior. The average particle size is 4.2 nm. There was high incorporation efficiency of maleimides in the magnetic nanogel. The release was of sustained character and there was a greater release when an external magnetic field was applied. The mathematical model that best explained the process of drug release by the magnetic hydrogel was that of Peppas-Sahlin. The magnetic nanogel proved to be an excellent candidate for use in drug-delivery systems.

Bioassay-guided fractionation of extracts from Hypericum perforatum in vitro roots treated with carboxymethylchitosans and determination of antifungal activity against human fungal pathogens.

The aim of this study was to individuate, by bioassay-guided fractionation, promising antifungal fractions and/or constituents from Hypericum perforatum subsp. angustifolium in vitro roots. Treatments with chitosan, O-carboxymethylchitosan (CMC) and its derivatives were used to improve xanthone production in the roots. The bioassay-guided fractionation of CMC-treated roots led to the individuation of an ethyl acetate fraction, containing the highest amount of xanthones (6.8%) and showing the best antifungal activity with minimal inhibitory concentration (MIC) values of 53.82, 14.18, and 36.52 µg/ml, against Candida spp., Cryptococcus neoformans and dermatophytes, respectively. From this fraction the prenylated xanthone, biyouxanthone D has been isolated and represented the 44.59% of all xanthones detected. For the first time in the present paper biyouxanthone D has been found in H. perforatum roots and tested against C. neoformans, dermatophytes, and Candida species. The xanthone showed the greatest antifungal activity against C. neoformans and dermatophytes, with MIC values of 20.16, 22.63 µg/ml. In conclusion, the results obtained in the present study demonstrated that CMC-treated Hpa in vitro root extracts represent a tool for the obtainment of promising candidates for further pharmacological and clinical studies.

Adsorption of Remazol Red 198 onto magnetic N-lauryl chitosan particles: equilibrium, kinetics, reuse and factorial design.

PURPOSE: The discharge of colored effluents from industries is an important environmental issue and it is indispensable to remove the dyes before the water gets back to the rivers. The magnetic adsorbents present the advantage of being easily separated from the aqueous system after adsorption by positioning an external magnetic field. METHODS: Magnetic N-lauryl chitosan (L-Cht/γ-Fe(2)O(3)) particles were prepared and characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, and vibrating sample magnetometry. Remazol Red 198 (RR198) was used as a reactive dye model for adsorption on L-Cht/γ-Fe(2)O(3). The adsorption isotherms were performed at 25°C, 35°C, 45°C, and 55°C and the process was optimized using a 2(3) factorial design (analyzed factors: pH, ionic strength, and temperature). The desorption and regeneration studies were performed in a three times cycle. RESULTS: The characterization of the material indicated that the magnetic particles were introduced into the polymeric matrix. The pseudo-second order was the best model for explaining the kinetics and the Langmuir-Freundlich was the best-fitted isotherm model. At room temperature, the maximum adsorption capacity was 267 mg g(-1). The material can be reused, but with a decrease in the amount of adsorbed dye. CONCLUSIONS: L-Cht/γ-Fe(2)O(3) is a promising material to remove RR198 and probably other similar reactive dyes from aqueous effluents.

Synthesis, characterization and in vitro drug release of magnetic N-benzyl-O-carboxymethylchitosan nanoparticles loaded with indomethacin.

Magnetic N-benzyl-O-carboxymethylchitosan nanoparticles were synthesized through incorporation and in situ methods and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and magnetization measurements. Indomethacin was incorporated into the nanoparticles via the solvent evaporation method. The indomethacin-loaded magnetic nanoparticles were characterized by the same techniques, and also by transmission electron microscopy. The nanoparticles containing the polymer showed a drug loading efficiency of between 60.8% and 74.8%, and the magnetic properties were not significantly affected by incorporation of the drug. The in vitro drug release study was carried out in simulated body fluid, pH 7.4 at 37°C. The profiles showed an initial fast release, which became slower as time progressed. The percentage of drug released after 5 h was between 60% and 90%, and the best fitting mathematical model for drug release was the Korsmeyer-Peppas model, indicating a Fickian diffusion mechanism.

Adsorption of As(III) on chitosan-Fe-crosslinked complex (Ch-Fe).

It was reported the adsorption of As(III) on the surface of the chitosan-Fe-crosslinked complex. Theoretical correlation of the experimental equilibrium adsorption data for As(III)/Ch-Fe system is best explained by the non-linearized form Langmuir-Freundlich isotherm model. At optimum conditions, pH 9.0, the maximum adsorption capacity, calculated using the Langmuir-Freundlich isotherm model was 13.4 mg g⁻¹. The adsorption kinetics of As(III) onto Ch-Fe are described by the pseudo-first-order kinetic equation. The results of the Mössbauer spectroscopy showed that there is no redox process on the surface of the adsorbent.

Release of tetracycline from O-carboxymethylchitosan films.

O-carboxymethylchitosan films containing tetracycline were prepared by the casting method. The films were hardened by reaction with glutaraldehyde-induced crosslinking and heat treatment at 90°C, 120°C and 150°C. The effect, on the films, of hardening methods, water uptake, moisture, drug release and antimicrobial activity against Staphylococcus aureus was evaluated. The O-carboxymethylchitosan films were soluble in simulated saliva and after treatment, and the water uptake of the films decreased as the temperature or presence of glutaraldehyde increased. The antimicrobial activity of tetracycline was preserved, and efficiency was dependent on the hardening treatment to which the films were submitted.

Adsorption of Cr(VI) using Fe-crosslinked chitosan complex (Ch-Fe).

In the present investigation, Fe-chitosan crosslinked is used as adsorbent for the removal of chromium from aqueous solutions. The influence of pH, temperature and other ions was evaluated. pH 2.0 was found to be the optimum pH for adsorption of Cr(VI) onto Ch-Fe. Coordination of unsaturated sites for the iron(III) complex of polymer were considered to be the adsorption sites for Cr(VI) species, the predominant species being HCrO(4)(-). The Langmuir and Langmuir-Freundlich adsorption isotherm models were applied to describe the isotherm parameter for Cr(VI) adsorption. The results indicate that the Langmuir-Freundlich adsorption model and maximum adsorption capacity was calculated as 295 mg/g at 25 degrees C, with pH 4.7. Cr(VI) uptake on the adsorbent decreased from 295 mg/g at 25 degrees C to 209 mg/g at 65 degrees C. Rate constants as a function of temperature were evaluated with the help of a proposed second order kinetic model. The other coexisting ions, nitrate, chlorides and sulphate influenced Cr(VI) adsorption.

Separation of bioactive biflavonoids from Rheedia gardneriana using chitosan modified with benzaldehyde.

This paper shows the influence of benzenic groups on the chitosan surface for the separation of bioactive biflavonoids from Rheedia gardneriana leaves The yield of the biflavonoids using chitin modified with benzaldehyde (CH-Bz) as adsorbent in column chromatography was higher than that achieved with silica gel and chitosan. The presence of benzenic groups decreases the polarity of chitosan and consequently the interaction of hydrogen bonding between phenolic hydroxyl (OH) of biflavonoids and amine groups of the adsorbent. Therefore, the separation of these compounds appears to be the result of hydrophobicity and pi-pi interaction among electrons from the aromatic ring in sorbent and biflavonoid molecules.

Separation of flavonoids from Aleurites moluccana leaves using chitosan modified with heptaldehyde.

Heptaldehyde-modified chitosan (heptyl-chitosan, CH-Hp) was investigated as adsorbent for chromatograhic separation of the flavonoids from A. moluccana. The amount of 2"-O-rhamnosylswertisin isolated (30.0 mg) was approx. twice as high as swertisin (17.5 mg). The improved surface hydrophobicity effected by the heptyl groups promoted the separation of flavonoids. From the results obtained, CH-Hp seems to be more suitable for separation of glycosylated flavonoids than other flavonoids. Thus, modified chitosan described here can be used for hydrophobic interaction chromatography as sucessfully illustrated with flavonoids.

Separation of C-glycoside flavonoids from Aleurites moluccana using chitin and full N-acetylated chitin.

This paper describes a comparative study using different chromatographic supports (fully N-acetylated chitin, chitin and silica gel) to separate the flavonoids swertisin and 2"-O-rhamnosylswertisin from Aleurites moluccana. The results show that the flavonoids have apparently been separated by the hydrogen bond between the stationary phase (chitin and chitin-100) and flavonoids under the conditions studied.