Although the shrinkage of polymethyl methacrylate (PMMA) bone cement has been tackled by the poly(methyl methacrylate‐co‐acrylic acid) [P(MMA‐AA)] bone cement due to the expandable P(MMA‐AA) copolymer in the solid phase, the hydrophobicity of PMMA and its solidification restrict simulated body fluid (SBF) diffusion and expansion properties. In this research, hydroxyethyl methacrylate (HEMA)‐modified P(MMA‐AA) bone cement (HMBC) is obtained by introducing HEMA into the liquid phase of P(MMA‐AA) bone cement. It is assumed that the dual water absorption networks can promote the SBF absorption capacity, thus resulting in the increased expansion behavior. The results demonstrate that the introduction of HEMA improves the hydrophilicity of the bulk. SBF absorption efficiency and swelling efficiency are promoted in the primary step of expansion. The porous structure of HMBC contributes to the increased SBF absorption and swelling in the second step of expansion behavior. Meanwhile, the remarkable absorption ratio and expansion ratio reach 88.5% and 97.4%, respectively. Furthermore, enhanced biocompatibility and osteogenesis activity provide HMBC as a promising biomaterial in the clinical setting. 相似文献
The present study investigated the effect of PMMA powder to liquid monomer (P/L) ratio and molecular weight of PMMA powder on the properties of PMMA cement. Two types of PMMA powder (Mw: 120,000 and 350,000) were prepared with different P/L ratios (based on wt/wt ratios); 0.75:1, 1:1, 1.25:1, and 1.5:1. Characterization of PMMA powders, handling characteristics and flexural properties of cured PMMA samples were investigated. In conclusion, low P/L ratio and high molecular weight of PMMA powders are desirable to produce PMMA cement with good handling properties and high flexural properties. 相似文献
Poly (methyl methacrylate) (PMMA) bone cement is widely used as a filler for repairing bone defects. To improve the effectiveness of the treatment for bone defects caused by metastatic bone tumours, we propose the formulation of PMMA cement containing titania (TiO2) and magnetite (Fe3O4) that offers high bone affinity, making the cement suitable for use in magnetic hyperthermia. The TiO2 and Fe3O4 contents of the PMMA cement varied from 20 to 45 mass%. The various cement samples were evaluated for their apatite-forming ability and heat-generation characteristics. The samples containing TiO2 in concentrations of 15 mass% or higher formed apatite on their surfaces within 14 days in a simulated body fluid. The heat-generation characteristics of the samples were evaluated by applying an alternating current (AC) magnetic field under the following conditions: |H| = 40 Oe and f = 600 kHz, or |H| = 100 Oe and f = 100 kHz. The surface temperatures of the samples containing 25 and 30 mass% Fe3O4 reached 42.3 and 44.8 °C, respectively, at |H| = 40 Oe and f = 600 kHz. During hyperthermia treatment, cancer cells die at temperatures higher than 42 °C, and the cement samples fabricated in this study could reach this temperature. However, since some degree of heat loss will occur in vivo, it is necessary to ensure that the temperature is higher than 42 °C by varying the AC magnetic field. Nevertheless, the fact that the samples containing Fe3O4 concentrations of 25 mass% or higher generated enough heat under the AC magnetic field makes them suitable for clinical use in hyperthermia. Thus, PMMA cement containing 15 mass% or more of TiO2 and 25 mass% or more of Fe3O4 should be investigated as a bioactive bone cement with a strong hyperthermia effect. 相似文献
The organic vapor absorption capacity of poly(methyl metacrylate) (PMMA), filled with oleic acid (OLEA) capped TiO2 nanocrystals (NCs) with curved shape, rod-like and spherical, is studied. The NC shape combined with the nature of the capping molecules can be used to enhance or reduce the PMMA ability to absorb different solvent molecules in a controlled way. Indeed, the arrangement of the ligands at the NC surface demonstrates an effective tool to control the extent of the interaction between the penetrating molecules and the embedded NCs from the outer to the inner specific chemical functionality of the coordinating ligand molecules. 相似文献
Graphene oxide (GO) and functionalized carbon nanotubes (f-CNTs) (each in the concentration range of 0.01-1.00 wt/wt%) were investigated as the reinforcing agent in a poly(methyl methacrylate) (PMMA)/hydroxyapatite (HA) bone cement. Mixed results were obtained for the changes in the mechanical properties determined (storage modulus, bending strength, and elastic modulus) for the reinforced cement relative to the unreinforced counterpart; that is, some property changes were increased while others were decreased. We postulate that this outcome is a consequence of the fact that each of the nanofillers hampered the polymerization process in the cement; specifically, the nanofiller acts as a scavenger of the radicals produced during polymerization reaction due to the delocalized π-bonds. Results obtained from the chemical structure and polymer chain size distribution determined, respectively, by nuclear magnetic resonance and size exclusion chromatography analysis, on the polymer extracted from the specimens support the postulated mechanism. Furthermore, in the case of the 0.5 wt/wt% GO-reinforced cement, we showed that when the concentration of the radical species in the PMMA bone cement was doubled, mechanical properties markedly improved (relative to the value in the unreinforced cement), suggesting suppression of the aforementioned scavenger activity. 相似文献
The dental composites based on poly(methyl methacrylate)/hydroxyapatite (PMMA/HA) were prepared through heat-processing polymer powder-liquid method, in the presence of poly(lactic acid) powder (PLA; 5–20 phr). The PLA powder enhanced the flexural modulus and strength of PMMA/HA composites. The Alamar Blue assay results indicated the PMMA/HA/PLA composites were able to sustain human gingival fibroblasts (HGF) cells growth. The images of live/dead cells confocal showed the populations of living cells on the composites surface were confluent and the survival of HGF cells on the PMMA composites surface are assured. These features suggested that the PLA powder reinforced PMMA/HA composites demonstrated excellent biocompatibility. 相似文献
AbstractThe aim of this study is to develop core shell microcapsules of bovine serum albumin (BSA) gel with a complex polyelectrolite multilayer shell of natural polysaccharides with opposite charges, pectin (P), chitosan (Chi), and hyaluronic acid (HA) respectively, encapsulating Doxorubicin (Dox) as a carrier for targeted anti-tumoral treatment of hepatic cell carcinoma (HCC). A sacrificial CaCO3 template method was used in order to obtain microcapsules with a BSA gel core and a layer-by-layer (Lbl) deposition technique of polyelectrolite complexes formed between P/Chi in the inner layers and HA/Chi in the outer shell layers. The preformed microcapsules, BSA gel/P/Chi/HA, noted as ms, have been applied for Dox encapsulation (ms-Dox). Dox encapsulation and release in different pH media were studied in order to elucidate the interactions between pH dependently charged species involved in the Dox loading/releasing processes. The structure characterization of ms/ms-Dox was evaluated by FTIR and UV-Vis spectroscopy, X-ray diffraction, thermal analy sis, optical microscopy, confocal laser scanning microscopy, and scanning electron microscopy. The in vitro study for citotoxicity assessment on normal and tumoral cells of both ms and ms-Dox was performed using mesenchymal stem cells (MSCs) and Hep2G HCC cell lines. Results of physical-chemical analyses confirm the successful encapsulation of Dox in ms, and the in vitro biological study recommends ms-Dox as a candidate for future in vivo research as a targeted anti-tumoral treatment modality applications. 相似文献
Poly(methyl methacrylate) (PMMA) brushes were grafted to the surface of cross-linked PMMA nanospheres for use as the polymer phase in the preparation of the two-solution bone cement. PMMA chains grafted on the core of the cross-linked PMMA nanostructures were hypothesized to impart viscosity to the cement mixture, while providing entanglements with the matrix chains formed during cement cure. The first goal of this study was to develop a novel synthetic strategy to decorate the surface of nanoparticles with functional groups that allowed for grafting of PMMA brushes via radical polymerization. The grafting reactions were performed at specific combinations of monomer and initiator to produce a range of molecular weights adequate for the preparation of bone cements. The second goal was to investigate the ability of this novel methodology to produce high graft densities on the core surface from the analysis of the hydrodynamic properties of brushes. The synthetic pathway discussed enabled the synthesis of brushes with high graft densities and molecular weights tuned to provide optimal viscosities for preparation of brush-containing two-solution bone cements. 相似文献
AbstractThe mixing of poly(methyl methacrylate) (PMMA) bone cement has been studied to develop methods for preparing a consistently high quality cement. A novel droplet test experimental procedure was developed that characterised the wetting characteristics involved in bone cement mixing. Using this technique it was established that increased wetting occurred by mixing bone cement at a lower temperature (-28°C) than normal mixing at room temperature.The effect of temperature on viscosity of the cement mix was also investigated. An increase in viscosity with mixing time was found for all temperatures (owing to dissolution of PMMA in the monomer). However, the rate of increase in viscosity was a function of the initial temperature of the cement components. Cooling of the components initially to -12·6°C resulted in a better mix than room temperature samples, due to the cooled components having more mixing time at a lower viscosity (less than 1000 cP).Automated mixing of the cement was also investigated. A high speed ‘figure of eight’ mixing machine (Kerr® AutomixTM computerised mixing dental amalgamator) was used in a comparison with traditional hand held mixing devices. The effect of initial component cooling was also investigated in the high speed unit and cement samples were analysed for porosity and homogeneity of mix (using scanning electron microscopy). Results indicate that the combined effects of low initial temperature and automated mixing produces a bone cement that is more homogeneous and of lower porosity than hand mixed cement. 相似文献
Summary: Clay/PMMA nanocomposites were prepared by melt blending of an organically modified MMT with PMMA under various process conditions. The MMT clay was initially cation exchanged with octadecylammonium to enhance its hydrophobicity and to expand the interlamellar space of the silicate plates. PMMA was then inserted into the inter‐lamellar space of the modified clay by melt blending at an elevated temperature. The effects of blending temperature, blending time, and clay/PMMA compositions on the level of expansion and homogenization were investigated. Composites with intercalated and/or exfoliated clay structure were obtained depending upon the process conditions, as confirmed by XRD diffractometry. The thermal decomposition temperature (Td) and glass transition temperature (Tg) of the composites were determined, respectively, by TGA and DSC analyses. Marked improvements, up to 35 °C, of the thermal stability (Td) with respect to pure PMMA were achieved for many of the composite samples. The Tg of the composites, however, does not increase accordingly. Furthermore, a novel type of bone cement was synthesized by applying the clay/PMMA nanocomposites as a substitute for PMMA in a typical formulation. These bone cements demonstrated much higher impact strength and better cell compatibility than the surgical Simplex P cement. Therefore, the bone cements with clay/PMMA nanocomposites meet the requirement for the architectural design of orthopedic surgery.