ABSTRACT
Coal fly ash-derived zeolites have attracted considerable interest in the last decade due to their use in several environmental applications such as the removal of dyes and heavy metals from aqueous solutions. In this work, coal fly ash-derived zeolites and silver nanoparticles-impregnated zeolites (nanocomposites) were synthesized and characterized by TEM/EDX, SEM/EDX, XRD, XRF, porosimetry (BET), particle size analysis (PSA) and zeta potential measurements. The synthesized materials were used for the removal of Hg2+ from aqueous solutions. The results demonstrated that nanocomposites can remove 99% of Hg2+, up to 10% and 90% higher than the removal achieved by the zeolite and the parent fly ash, respectively. Leaching studies further demonstrated the superiority of the nanocomposite over the parent materials. The Hg2+ removal mechanism is complex, involving adsorption, surface precipitation and amalgamation.
Subject(s)
Coal Ash , Mercury/isolation & purification , Metal Nanoparticles , Zeolites , Adsorption , Coal , Mercury/chemistry , Silver , Water , Water PurificationABSTRACT
Conditions such as diabetes, cardiovascular disease and long-term immobilisation can precipitate the development of chronic dermal ulcers. Such wounds are associated with inflammation and bacterial contamination which in turn can lead to the liberation of offensive odours that cause patient embarrassment and, in some instances, social isolation. Activated carbon-containing dressings have been used to manage the odours from such wounds. However, these can be bulky and can become fouled by wound exudate. Agarose is a natural polysaccharide derived from seaweed that forms brittle free-standing films that can be made pliable by addition of a plasticiser. In this study, activated carbon-containing plasticised agarose films were evaluated for their ability to sequester thiol-containing molecules from solution and the gaseous phase. The water vapour transmission rate was also evaluated to determine the potential breathability of these films should they be considered for application to the skin. It was found that the adsorption of thiols was directly proportional to the activated carbon content of the films. Water vapour was found to pass relatively freely through the films indicating that sweat-induced tissue maceration would be unlikely to occur if applied clinically. In conclusion, activated carbon-containing plasticised agarose films have some potential in the sequestration of malodourous molecules such as those liberated from chronic dermal wounds.
Subject(s)
Bandages , Charcoal , Plasticizers , Sepharose/chemistry , Sulfhydryl Compounds/chemistry , Adsorption , Membranes, ArtificialABSTRACT
Macroporous cryogels containing mixtures of two key components of the dermal extracellular matrix, fibrinogen and collagen-derived gelatin, were evaluated for use as dermal tissue regeneration scaffolds. The infiltration of human dermal fibroblasts into these matrices was quantitatively assessed in vitro using a combination of cell culture and confocal laser scanning microscopy. The extent of cellular infiltration, as measured by the number of cells per distance travelled versus time, was found to be positively correlated with the fibrinogen concentration of the cryogel scaffolds; a known potentiator of cell migration and angiogenesis within regenerating tissue. An analysis of the proteins expressed by infiltrating fibroblasts revealed that the cells that had migrated into the interior portion of the scaffolds expressed predominantly F-actin along their cytoplasmic stress fibres, whereas those present on the periphery of the scaffolds expressed predominantly α-smooth muscle actin, indicative of a nonmotile, myofibroblast phenotype associated with wound contraction. In conclusion, the cryogels produced in this study were found to be biocompatible and, by alteration of the fibrinogen content, could be rendered more amenable to cellular infiltration.
Subject(s)
Cryogels/chemistry , Fibrinogen/chemistry , Gelatin/chemistry , Tissue Scaffolds/chemistry , Acellular Dermis/metabolism , Actins/physiology , Biocompatible Materials , Cell Culture Techniques , Cell Movement , Collagen/chemistry , Cryogels/metabolism , Extracellular Matrix , Humans , Phenotype , Regeneration , Tissue Engineering , Wound HealingABSTRACT
The structural, textural, and adsorption characteristics of mechanochemically activated (MCA) fumed silica A-300 as dry or water, ethanol, or water/ethanol-wetted powders (0.5 g of a solvent per gram of silica) in a ball mill for 1-6 h were studied in comparison with those of the initial powder. The MCA treatment enhances bulk density (ρ(b)) of the powder (from 0.045 g/cm(3) for the initial silica to 0.4 g/cm(3) for 6 h-MCA-treated water-wetted silica) depending on medium type and MCA time (t(MCA)). Stronger effects are observed for the MCA treatment of water-wetted silica than of dry or ethanol- or water/ethanol-wetted samples. The MCA treatment weakly affects the specific surface area (S(BET)). However, void (pore) size distribution, porosity, particle aggregation and size distribution in aqueous suspension, behavior of interfacial water, properties of poly(vinyl alcohol)/silica composites and adsorption of gelatin depend more strongly on the t(MCA) and ρ(b) values. Some of the observed changes in the characteristics (e.g., gelatin adsorption) depend on the ρ(b) value but are independent of the medium type used on the MCA. Other characteristics are nonlinear functions of both t(MCA) and ρ(b) values.
Subject(s)
Gelatin/chemistry , Nanostructures/chemistry , Silicon Dioxide/chemistry , Adsorption , Gelatin/metabolism , Particle Size , Porosity , Silicon Dioxide/metabolism , Solvents/chemistry , Surface Properties , Suspensions , Water/chemistry , WettabilityABSTRACT
Adsorption of low-molecular adsorbates (nonpolar hexane, nitrogen, weakly polar acetonitrile, and polar diethylamine, triethylamine, and water) onto individual (silica, alumina, titania), binary (silica/alumina (SA), silica/titania (ST)), and ternary (alumina/silica/titania, AST) fumed oxides was studied to analyse the effects of morphology and surface composition of the materials. Certain aspects of the interfacial phenomena dependent on the structural characteristics of oxides were analysed using calorimetry, (1)H NMR, and Raman spectroscopies, XRD, and ab initio quantum-chemical calculations. The specific surface area S(BET,X)-to-S(BET,N(2)) ratio (X is an organic adsorbate) changes from 0.68 for hexane adsorbed onto amorphous SA8 (degassed at 200 degrees C) to 1.85 for acetonitrile adsorbed onto crystalline alumina (degassed at 900 degrees C). These changes are relatively large because of variations in orientation, lateral interactions, and adsorption compressing of molecules adsorbed onto oxide surfaces. Larger S(BET,X)/S(BET,N(2)) values are observed for mixed oxides with higher crystallinity of titania or/and alumina phases in larger primary nanoparticles with greater surface roughness and hydrophilicity. Polar adsorbates can change the structure of aggregates of oxide nanoparticles that can, in turn, affect the results of adsorption measurements.
Subject(s)
Aluminum Oxide/chemistry , Nanoparticles/chemistry , Oxides/chemistry , Silicon Dioxide/chemistry , Titanium/chemistry , Acetonitriles/chemistry , Adsorption , Diethylamines/chemistry , Ethylamines/chemistry , Hexanes/chemistry , Magnetic Resonance Spectroscopy , Models, Molecular , Nitrogen/chemistry , Surface Properties , Water/chemistryABSTRACT
Calcium phosphate was deposited on carbon materials using a sonoelectrochemical method in an electrolyte containing calcium and phosphate ions. The effect of electrolyte concentration on sonoelectrochemically deposited calcium phosphate coatings was investigated and the underlying deposition mechanisms were discussed. The morphology, size and composition of the crystalline deposits changed with the electrolyte concentration. A mixture of plate, sphere and needle-like deposits was obtained at Ca(2+) ion concentrations greater than 16 mM, however needle-like hydroxyapatite (HA) was obtained at lower Ca(2+) concentrations. Analysis revealed that the sonoelectrochemical deposition of calcium phosphate consists of two processes-nucleation and crystal growth. The results suggest that the homogeneous nucleation of calcium phosphates in solution, followed by their absorption onto the carbon surface may account for the mechanism of coating observed at higher ionic concentrations. At lower concentrations, heterogeneous nucleation occurs on the surface of the carbon fibres, followed by the development of islands of crystal growth. The lower ionic concentration was shown to favour the generation of hydroxyapatite on carbon-based materials.
Subject(s)
Calcium Phosphates/chemistry , Carbon/chemistry , Electrolytes/chemistry , Electrochemistry , Microscopy, Electron, Scanning , Spectroscopy, Fourier Transform InfraredABSTRACT
Calcium phosphate (CaP) coatings on carbon fabric substrate were produced by sonoelectrodeposition at different current densities (5, 8, 13, 20 and 34 mA/cm2). The surface morphology and chemical composition of the coatings were characterized by SEM, Raman and FTIR spectra. The results showed that at 5 mA/cm2 current density, the coating exhibits plate-like morphology, indicating an octacalcium phosphate (OCP) phase was pre-formed in the deposits and then converted into hydroxyapatite (HA). When the current density was increased to 8 mA/cm2 and higher, the coatings exhibited needle-like morphology corresponding to a HA phase. Furthermore, the sonoelectrodeposited CaP coating exhibited denser and more uniform structures with smaller crystal sizes as the current density increased. Cathodic reaction mechanisms of CaP coatings on carbon in the sonoelectrochemical processes are proposed to explain the different kinds of calcium phosphate obtained.
Subject(s)
Calcium Phosphates/chemistry , Carbon/chemistry , Coated Materials, Biocompatible , Electrochemistry/methods , Crystallization , Durapatite/chemistry , Equipment Design , Ions , Materials Testing , Microscopy, Electron, Scanning , Models, Chemical , Osseointegration , Spectroscopy, Fourier Transform Infrared/methods , Spectrum Analysis, Raman/methods , Surface PropertiesABSTRACT
The article is devoted to the theoretical aspects of the development of the effective method for the removal of protein-bound uremic toxins. It is shown that the methods of flow and differential scanning microcalorimetry are sufficient enough for the evaluation of the degree of ligand loading of human serum albumin with protein-bound uremic toxins. The molecules of albumin isolated from blood plasma of the patients being kept on chronic dialysis are demonstrating significant alterations of conformation and complex-forming properties, the correction of which by conventional methods of extracorporeal detoxification (exhaustive dialysis, treatment on synthetic SCN carbons) are practically ineffective. Deliganding of uremic albumin may be successfully performed on conventional carbon haemosorbents upon preliminary separation of blood plasma and its dilution with acetate buffer 1:1 at pH = 5.08. Treatment of the whole blood of patients onto new mass-fractal deliganding carbon, i.e., hemosorbents of HSGD trademark. These HSGD haemosorbents quite effectively could be used for restoration of main parameters of uremic HAS molecules conformation and ligand-binding activity simultaneously with hemodialysis upon the protection by locally performed citrate anticoagulation as an easier and cheaper method for the removal of protein-bound uremic toxins.
Subject(s)
Charcoal/chemistry , Charcoal/therapeutic use , Serum Albumin/drug effects , Toxins, Biological/blood , Toxins, Biological/chemistry , Uremia/blood , Uremia/drug therapy , Adsorption , Binding Sites , Calorimetry, Differential Scanning/methods , Charcoal/metabolism , Furans/blood , Hemoperfusion , Hippurates/blood , Humans , Hydrogen-Ion Concentration , Indican/blood , Membranes, Artificial , Plasma/metabolism , Propionates/blood , Protein Binding , Reference Values , Renal Dialysis/methods , Serum Albumin/metabolism , Treatment OutcomeABSTRACT
The thermodynamic miscibility, morphology, phase distribution, mechanical properties, surface properties, water sorption, bacterial adhesion and cytotoxicity of semi-interpenetrating polymer networks (semi-IPNs) based on crosslinked polyurethane (PU) and poly(hydroxyethylmethacrylate) (PHEMA) were studied to give an insight into their structure and properties. The free energies of mixing of the two polymers in semi-IPNs have been determined and it was shown that the values are positive and depend on the amount of PHEMA. This demonstrates that the components are immiscible, the extent of which is dependent upon variations in composition. The morphology of the semi-IPNs was analyzed with scanning electron microscopy and tapping mode atomic force microscopy (TMAFM). The micrographs of the semi-IPNs and TMAFM phase images indicated that distinct phase separation at the nanometer scale is observed. The mechanical properties reflect the changes in structure of semi-IPNs with composition. The stress at break increases from 3.4 MPa to 23.9 MPa, and the Young's modulus from 12.7 MPa up to 658.5 MPa with increasing amounts of PHEMA, but strain at break has a maximum at 40.4% PHEMA. The bacterial adhesion and cytotoxicity data suggest that semi-IPNs with PHEMA content above 22% may be used for biomedical material applications.
Subject(s)
Biocompatible Materials , Polyhydroxyethyl Methacrylate , Polyurethanes , Absorbable Implants , Bacterial Adhesion , Biocompatible Materials/adverse effects , Biocompatible Materials/pharmacokinetics , Biocompatible Materials/toxicity , Cells, Cultured , Colony-Forming Units Assay , Inhibitory Concentration 50 , Microscopy, Atomic Force , Polyhydroxyethyl Methacrylate/pharmacokinetics , Polyhydroxyethyl Methacrylate/toxicity , Polyurethanes/pharmacokinetics , Polyurethanes/toxicity , Staphylococcus aureus/physiology , Surface PropertiesABSTRACT
The influence of proteins (bovine serum albumin, BSA, and mouse gamma-globulin, IgG) physically adsorbed or covalently attached via coupling with N-cyclohexyl-N'-(2-morpholinoethyl) carbodiimide methyl-p-toluenesulfonate, CMC, to the surface of activated carbon SCN (spherical carbon with nitrogen) on the mobility of interfacial water molecules was studied by means of 1H NMR spectroscopy with freezing-out of bulk water at 180 < T < 273 K. Relaxation processes in the interfacial non-freezing water were investigated measuring transverse time t2 of proton relaxation dependence on the presence of proteins and CMC. The distribution function of activation free energy of relaxation (with a maximum at 20-22 kJ/mol) was calculated for the protein-water-carbon systems using a regularization procedure and the relationships between t2 and the amounts of the interfacial water unfrozen at T < 250 K assuming the Arrhenius-type dependence for t2(-1) on temperature. The state of unfrozen water in pores of SCN shows that the low temperature relaxation processes occur in narrow pores with half-width X < 1.5 nm.
Subject(s)
Carbon/chemistry , Immunoglobulin G/chemistry , Serum Albumin, Bovine/chemistry , Water/chemistry , gamma-Globulins/chemistry , Adsorption , Animals , Cattle , Magnetic Resonance Spectroscopy , Mice , TemperatureABSTRACT
Structural characteristics of a series of MAST carbons were studied using scanning electron microscopy images and the nitrogen adsorption isotherms analyzed with several models of pores and different adsorption equations. A developed model of pores as a mixture of gaps between spherical nanoparticles and slitlike pores was found appropriate for MAST carbons. Adsorption of ibuprofen [2-(4-isobutylphenyl)propionic acid] on activated carbons possessing different pore size distributions in protein-free and bovine serum albumin (BSA)-containing aqueous solutions reveals the importance of the contribution of mesopores to the total porosity of adsorbents. The influence of the mesoporosity increases when considering the removal of the drug from the protein-containing solution. Cellulose-coated microporous carbon Norit RBX adsorbs significantly smaller amounts of ibuprofen than uncoated micro/mesoporous MAST carbons whose adsorption capability increases with increasing mesoporosity and specific surface area, burnoff dependent variable. A similar effect of broad pores is observed on adsorption of fibrinogen on the same carbons. Analysis of the ibuprofen adsorption data using Langmuir and D'Arcy-Watt equations as the kernel of the Fredholm integral equation shows that the nonuniformity of ibuprofen adsorption complexes diminishes with the presence of BSA. This effect may be explained by a partial adsorption of ibuprofen onto protein molecules immobilized on carbon particles and blocking of a portion of narrow pores.
Subject(s)
Carbon/chemistry , Ibuprofen/chemistry , Serum Albumin, Bovine/chemistry , Adsorption , Animals , Cattle , Humans , Models, Molecular , Nitrogen/chemistry , Serum Albumin/chemistry , Surface PropertiesABSTRACT
The ion exchange properties of the titanium silicate, M2Ti2O3SiO4.nH2O (M = H, Na), toward stable and radioactive 137Cs+ and 89Sr2+, have been examined. By studying the cesium and strontium uptake in the presence of NaNO3, CaCl2, NaOH, and HNO3 (in the range of 0.01-6 M) the sodium titanium silicate was found to be an efficient Cs+ ion exchanger in acid, neutral, and alkaline media and an efficient Sr2+ ion exchanger in neutral and alkaline media, which makes it promising for treatment of contaminated environmental media and biological systems.
Subject(s)
Cesium/chemistry , Silicates/chemistry , Strontium/chemistry , Titanium/chemistry , Environmental Pollutants/analysis , Environmental Pollution/prevention & control , Ion ExchangeABSTRACT
The ability of an injured cornea to regenerate from deep tissue trauma is largely due to wound healing processes mediated by the surviving stromal keratocytes. Despite the importance of the wound healing process, and the ease with which keratocytes can be grown in tissue culture, a standardised strain of the cells has never been made available. Accordingly, this study reports a strain of human embryonic keratocytes, designated EK1.BR as a research tool for the ophthalmic community. EK1.BR has been characterised with respect to life-span, fraction of dividing cells and maintenance of a keratocyte phenotype in culture. It is hoped that these cells will prove useful in the in vitro study of stromal wound healing and the characterisation of keratocyte gene expression.
Subject(s)
Corneal Stroma/cytology , Aged , Aging/physiology , Aminopeptidases/genetics , Aminopeptidases/metabolism , Cell Movement , Cells, Cultured , Corneal Stroma/enzymology , Corneal Stroma/growth & development , DNA/biosynthesis , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/genetics , Dipeptidyl-Peptidases and Tripeptidyl-Peptidases/metabolism , Exopeptidases , Fetus , Fibroblasts/cytology , Fibroblasts/enzymology , Gene Expression , Humans , Lysosomes/enzymology , Methionyl Aminopeptidases , Mitosis , Peptide Hydrolases/genetics , Peptide Hydrolases/metabolism , Tissue Donors , Wound Healing/physiology , beta-Galactosidase/genetics , beta-Galactosidase/metabolismABSTRACT
Recent developments in ocular implant technology require the in vitro evaluation of ocular compatibility in early stage development programs. This requires an understanding and appreciation of the biological interactions which occur in the ocular environment and their relevance with respect to the clinical complications associated with surgical implantation of devices. This paper describes the development of a series of clinically reflective in vitro assays for assessing the potential ocular compatibility of novel intraocular lens materials. Staphylococcus epidermidis attachment, fibrinogen adsorption, mouse embryo fibroblast 3T3 adhesion and proliferation, primary rabbit lens cell adhesion, human peripheral blood macrophage adhesion and granulocyte activation tests were employed to evaluate two widely used intraocular biomaterials poly(methyl methacrylate) (PMMA) and silicone, and a novel biomimetic phosphorylcholine-based coating (PC). The performance of these materials in the in vitro assays was compared to their ability to reduce postoperative inflammation in vivo in a rabbit model. The results demonstrated that the in vitro assays described here are predictive of in vivo ocular compatibility. These assays offer a more relevant means of assessing the ocular compatibility of biomaterials than those presently required by the authorities for regulatory approval of medical devices and implants.
ABSTRACT
By means of water-soluble carbodiimide coupling technique various bioligands were covalently attached to the surface of uncoated synthetic active carbons and a number of sorbents with certain biological functions were thus designed. Carbonaceous sorbents with immobilized ligands demonstrate increased affinity towards specific sorbates compared to that of starting matrix. As soon as SCN and SCS synthetic carbons are used uncoated they can be highly loaded with protein molecules - up to 80 mg serum albumin, 6-10 mg IgG rabbit etc. per gram of sorbent. Carbonaceous immunosorbents retain biocompatibility and substantial non-specific adsorptive capacity of initial hemosorbents. A conclusion is drawn that uncoated synthetic charcoals can serve a basis for design of selective hemosorbents intended for solving complicated problems of immunocorrection.