Practical applications of Phase Change Materials (PCMs) often require their encapsulation in other materials, such as metals or plastics. This raises the issue of compatibility between PCMs and encapsulating materials, which has still not been sufficiently addressed. The study presented here follows existing research and provides experimental evaluation of the suitability of selected PCMs for proposed integration in building structures. Two organic PCMs, two inorganic PCMs and three representative plastics (polypropylene (PP-H), high density polyethylene (PE-HD) and polyvinylchloride (PVC-U)) were selected for compatibility tests. Evaluation of the results is based on the mass variations of the plastic samples during the test period. Plastic samples were immersed in PCMs and subjected to periodic heating and cooling (for 16 weeks) in a small environmental chamber simulating real operational conditions. The results show that the organic PCMs have a greater ability to penetrate the PE-HD and PP-H compared with the inorganic PCMs. The penetration of all PCMs was most notable during the first four weeks of the experiment. Later it slowed down significantly. Overall, the mass changes in PE-HD and PP-H samples did not exceed 6.9% when immersed in organic PCMs and 1.8% in inorganic PCMs. PVC-U samples exhibited almost negligible (less than 0.1%) mass variation in all cases.
- MeSH
- polyethylen chemie MeSH
- polypropyleny chemie MeSH
- polyvinylchlorid chemie MeSH
- Publikační typ
- časopisecké články MeSH
Passive sampling is increasingly applied for monitoring neutral hydrophobic compounds (HOC) in various environmental media like water, sediment, air and also soft biota tissue. Passive samplers for HOC are often constructed from permeable polymers like silicone and polyethylene (PE), while also SPMD are often applied. Their HOC uptake can be converted to freely dissolved or equivalent lipid-based concentrations using appropriate partition coefficients with or without the use of kinetic uptake models to adjust for non-equilibrium. To facilitate such conversions for seventy HOC partition coefficients are derived by combining polymer-water for Altesil™ silicone and PE, with new and earlier published polymer-polymer, polymer-lipid partition coefficients. Derived SSP silicone-water, lipid-water (Klip/w), and SPMD-water (Kspmd/w) partition coefficients demonstrate good agreement with literature data, except for Kspmd/w. For SPMD, this work demonstrates a linear Kspmd/w - Kow relationship (R2 = 0.99) in contrast to the parabolic Kspmd/w - Kow relationship utilized in the USGS "SPMD Water Concentrations Calculator". Following a thorough evaluation of this Calculator it is recommended that in combination with revised Kspmd/w, a radical different model approach should be used for obtaining accurate water concentrations from passive sampling with SPMD.
- MeSH
- chemické látky znečišťující vodu chemie MeSH
- hydrofobní a hydrofilní interakce MeSH
- lipidy chemie MeSH
- monitorování životního prostředí MeSH
- polycyklické aromatické uhlovodíky analýza MeSH
- polyethylen chemie MeSH
- polymery chemie MeSH
- silikony chemie MeSH
- voda chemie MeSH
- Publikační typ
- časopisecké články MeSH
Ultra-high molecular weight polyethylene (UHMWPE) is the most important but, at the same time, the most vulnerable component of the total joint replacements. It is mainly used in hip and knee replacements. UHMWPE liners are the most loaded components of the implants. Consequently, the main material-related reasons of artificial joint failures are wear and oxidative degradation of the polymer. Resistance to wear is increased by radiation-induced crosslinking. Oxidation stability is enhanced by means of suitable thermal treatment. The most recent trend is to employ a biocompatible stabilizer based on the α-tocopherol in combination with suitable types of steric hindered amines for further improvement and fine-tuning of UHMWPE performance. This review summarizes the recent developments in UHMWPE modifications which should further increase lifespan of total joint replacements.
- MeSH
- alfa-tokoferol chemie MeSH
- antioxidancia chemie klasifikace MeSH
- chemické jevy MeSH
- ionizující záření MeSH
- lidé MeSH
- oxidace-redukce MeSH
- polyethylen * chemie MeSH
- protézy kloubů * MeSH
- selhání protézy MeSH
- synoviální tekutina MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
Ultra-high molecular weight polyethylene (UHMWPE) is used as a bearing material in total joint replacements. These joint replacements are in contact with the body fluids during their lifetime, resulting in material degradation. Due to the limited flow behaviour and the large number of physical entanglements of UHMWPE, some measurements (rheological measurements, determination of the gel content and extractable fraction, etc.) cannot be properly evaluated. Therefore, we have focused on accelerated aging of high density polyethylene (HDPE) in the hydrogen peroxide oxidation environment, allowing complete evaluation of degradation damage by monitoring mechanical, rheological, thermal and spectroscopic changes of the material. Perspective amine antioxidants (HALS) and the classical phenolic stabilizer α-tocopherol were used for HDPE stabilization and their effects compared. The aim of the work was to find an effective and rapid method of evaluating the antioxidant effect of newly developed stabilizers for UHMWPE using accelerated aging tests of lower molecular weight analogues. The results have shown that radiation crosslinking of HDPE leads to materials with higher sensitivity to oxidation. All tested stabilizers effectively inhibited the oxidation of HDPE. Moreover, after irradiation and subsequent aging, the branching of HALS stabilizer-containing HDPE chains took place which resulted in increased material resistance.
The type of tissue response to implant by-products can be determined by examination of periprosthetic tissues. However, little is known about the most suitable location for tissue sampling. The main goal of this study was to evaluate the extent of variability in tissue response in relation to location of tissue sampling, implant fixation, age and sex in total joint arthroplasties with metal-on-polyethylene or ceramic-on-polyethylene bearing pairs. We processed 236 histology slides from 21 patients and focused on the association between the location of tissue samples and histological features. The presence of the synovial hyperplasia showed a significant association with the particular sampling site. A higher density of high endothelial cell venules was seen in the samples from around the joint, and polyethylene particles were more abundant in noncemented TJA but both findings did not show statistically significant association with the sampling site. The results showed a relatively small variance in the tissue response to prosthetic by-products among tissues sampled from the same patient. Our findings indicate that tissue samples retrieved from similar distance from around the TJA during the revision operation show comparable results of histological analysis. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2008-2018, 2018.
- MeSH
- keramika * škodlivé účinky chemie MeSH
- kyčelní protézy * MeSH
- lidé středního věku MeSH
- lidé MeSH
- náhrada kyčelního kloubu * MeSH
- polyethylen * škodlivé účinky chemie MeSH
- protézy - design * MeSH
- retrospektivní studie MeSH
- rozhraní kost/implantát patologie MeSH
- selhání protézy * MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři nad 80 let MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Polymeric biomaterials with antibacterial effects are requisite materials in the fight against hospital-acquired infections. An effective way for constructing a second generation of antibacterials is to exploit the synergic effect of (i) patterning of polymeric materials by a laser, and (ii) deposition of noble metals in their nanostructured forms. With this approach, we prepared highly-ordered periodic structures (ripples) on polyethylene naphthalate (PEN). Subsequent deposition of Ag under the glancing angle of 70° resulted in the formation of self-organized, fully separated Ag nanowire (Ag NW) arrays homogenously distributed on PEN surface. Surface properties of these samples were characterized by AFM and XPS. Vacuum evaporation of Ag at the glancing angle geometry of 70° caused that Ag NWs were formed predominantly from one side of the ripples, near to the top of the ridges. The release of Ag(+) ions into physiological solution was studied by ICP-MS. The results of antibacterial tests predetermine these novel structures as promising materials able to fight against a broad spectrum of microorganisms, however, their observed cytotoxicity warns about their applications in the contact with living tissues.
- MeSH
- antibakteriální látky chemie farmakologie MeSH
- Escherichia coli účinky léků MeSH
- fotoelektronová spektroskopie MeSH
- lasery * MeSH
- mikroskopie atomárních sil MeSH
- nanodráty chemie toxicita MeSH
- polyethylen chemie MeSH
- povrchové vlastnosti MeSH
- Staphylococcus epidermidis účinky léků MeSH
- stříbro chemie MeSH
- Publikační typ
- časopisecké články MeSH
Non-conventional antimicrobial agents, such as palladium nanostructures, have been increasingly used in the medicinal technology. However, experiences uncovering their harmful and damaging effects to human health have begun to appear. In this study, we have focused on in vitro cytotoxicity assessment of Pd nanostructures supported on a biocompatible polymer. Pd nanolayers of variable thicknesses (ranging from 1.1 to 22.4nm) were sputtered on polyethylene naphthalate (PEN). These nanolayers were transformed by low-temperature post-deposition annealing into discrete nanoislands. Samples were characterized by AFM, XPS, ICP-MS and electrokinetic analysis before and after annealing. Sterilization of samples prior to cytotoxicity testing was done by UV irradiation, autoclave and/or ethanol. Among the listed sterilization techniques, we have chosen the gentlest one which had minimal impact on sample morphology, Pd dissolution and overall Pd/PEN interface quality. Cytotoxic response of Pd nanostructures was determined by WST-1 cell viability assay in vitro using three model cell lines: mouse macrophages (RAW 264.7) and two types of mouse embryonic fibroblasts (L929 and NIH 3T3). Finally, cell morphology in response to Pd/PEN was evaluated by means of fluorescence microscopy.
- MeSH
- buněčná smrt účinky léků MeSH
- buňky NIH 3T3 MeSH
- fibroblasty cytologie účinky léků MeSH
- mikroskopie atomárních sil MeSH
- myši MeSH
- naftaleny chemie MeSH
- nanostruktury chemie MeSH
- palladium farmakologie MeSH
- polyethylen chemie MeSH
- polyethyleny chemie MeSH
- povrchové vlastnosti MeSH
- RAW 264.7 buňky MeSH
- statická elektřina MeSH
- sterilizace * MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Polymers are increasingly used for passive sampling of neutral hydrophobic organic substances (HOC) in environmental media including water, air, soil, sediment and even biological tissue. The equilibrium concentration of HOC in the polymer can be measured and then converted into equilibrium concentrations in other (defined) media, which however requires appropriate polymer to media partition coefficients. We determined thus polymer-lipid partition coefficients (KPL) of various PCB, PAH and organochlorine pesticides by equilibration of two silicones and low density polyethylene (LDPE) with fish oil and Triolein at 4 °C and 20 °C. We observed (i) that KPLwas largely independent of lipid type and temperature, (ii) that lipid diffusion rates in the polymers were higher compared to predictions based on their molecular volume, (iii) that silicones showed higher lipid diffusion and lower lipid sorption compared to LDPE and (iv) that absorbed lipid behaved like a co-solute and did not affect the partitioning of HOC at least for the smaller molecular size HOC. The obtained KPLcan convert measured equilibrium concentrations in passive sampling polymers into equilibrium concentrations in lipid, which then can be used (1) for environmental quality monitoring and assessment, (2) for thermodynamic exposure assessment and (3) for assessing the linkage between passive sampling and the traditionally measured lipid-normalized concentrations in biota. LDPE-lipid partition coefficients may also be of use for a thermodynamically sound risk assessment of HOC contained in microplastics.
- MeSH
- chlorované uhlovodíky chemie izolace a purifikace MeSH
- fyzikální absorpce * MeSH
- hydrofobní a hydrofilní interakce MeSH
- látky znečišťující životní prostředí chemie izolace a purifikace MeSH
- lipidy chemie MeSH
- organické látky chemie izolace a purifikace MeSH
- polyethylen chemie MeSH
- regenerace a remediace životního prostředí metody MeSH
- silikony chemie MeSH
- vystavení vlivu životního prostředí prevence a kontrola MeSH
- Publikační typ
- časopisecké články MeSH
Five types of amide-amine Carbon Nano-Particles (CNPs) were prepared by functionalization of CNPs and characterized by several analytical methods. The successful grafting of amines on CNPs was verified by X-ray photoelectron spectroscopy (XPS), organic elemental analysis and electrokinetic analysis. The size and morphology of CNPs were determined from transmission electron microscopy. The surface area and porosity of CNPs were examined by adsorption and desorption isotherms. Differential scanning calorimetry was used to investigate thermal stability of CNPs. The amount of bonded amine depends on its dimensionality arrangement. Surface area and pore volumes of CNPs decrease several times after individual amino-compound grafting. Selected types of functionalized CNPs were grafted onto a plasma activated surface of HDPE. The successful grafting of CNPs on the polymer surface was verified by XPS. Wettability was determined by contact angle measurements. Surface morphology and roughness were studied by atomic force microscopy. A dramatic decrease of contact angle and surface morphology was observed on CNP grafted polymer surface. Cytocompatibility of modified surfaces was studied in vitro, by determination of adhesion, proliferation and viability of vascular smooth muscle cells (VSMCs). Grafting of CNPs onto the polymer surface has a positive effect on the adhesion, proliferation and viability of VSMCs.
- MeSH
- aminy chemie MeSH
- kultivované buňky MeSH
- lidé MeSH
- myocyty hladké svaloviny cytologie účinky léků MeSH
- nanočástice škodlivé účinky chemie MeSH
- polyethylen chemie MeSH
- proliferace buněk účinky léků MeSH
- smáčivost MeSH
- svaly hladké cévní cytologie MeSH
- uhlík chemie MeSH
- viabilita buněk účinky léků MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Beside biomaterials' bulk properties, their surface properties are equally important to control interfacial biocompatibility. However, due to the inadequate interaction with tissue, they may cause foreign body reaction. Moreover, surface induced thrombosis can occur when biomaterials are used for blood containing applications. Surface modification of the biomaterials can bring enhanced surface properties in biomedical applications. Sulfated polysaccharide coatings can be used to avoid surface induced thrombosis which may cause vascular occlusion (blocking the blood flow by blood clot), which results in serious health problems. Naturally occurring heparin is one of the sulfated polysaccharides most commonly used as an anticoagulant, but its long term usage causes hemorrhage. Marine sourced sulfated polysaccharide fucoidan is an alternative anticoagulant without the hemorrhage drawback. Heparin and fucoidan immobilization onto a low density polyethylene surface after functionalization by plasma has been studied. Surface energy was demonstrated by water contact angle test and chemical characterizations were carried out by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Surface morphology was monitored by scanning electron microscope and atomic force microscope. Finally, their anticoagulation activity was examined for prothrombin time (PT), activated partial thromboplastin time (aPTT), and thrombin time (TT).
- MeSH
- antikoagulancia škodlivé účinky chemie farmakologie MeSH
- heparin škodlivé účinky chemie farmakologie MeSH
- krev účinky léků MeSH
- lidé MeSH
- polyethylen chemie MeSH
- polysacharidy škodlivé účinky chemie farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
