首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 406 毫秒
1.
The purpose of this study was to study the mechanical properties of poly(methyl methacrylate) (PMMA)‐based bone cement incorporated with hydroxyapatite (HA) nanoparticles after surface modification by poly(methyl methacrylate‐co‐γ‐methacryloxypropyl timethoxysilane) [P(MMA‐co‐MPS)]. PMMA and P(MMA‐co‐MPS) were synthesized via free‐radical polymerization. P(MMA‐co‐MPS)‐modified hydroxyapatite (m‐HA) was prepared via a dehydration process between silane and HA; the bone cement was then prepared via the in situ free‐radical polymerization of methyl methacrylate in the presence of PMMA and P(MMA‐co‐MPS)–m‐HA. Fourier transform infrared (FTIR) spectroscopy, 1H‐NMR, and gel permeation chromatography were used to characterize the P(MMA‐co‐MPS). Thermogravimetric analysis and FTIR were used as quantitative analysis methods to measure the content of P(MMA‐co‐MPS) on the surface of HA. The effect of the proportion of m‐HA in the PMMA‐based bone cement on the mechanical properties was studied with a universal material testing machine. A 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay was also carried out to determine the cytotoxicity of the composite bone cement. The results showed that the surface modification of HA greatly improved the interaction between the inorganic and organic interfaces; this enhanced the mechanical properties of bone cement for potential clinical applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40587.  相似文献   

2.
To design bone cements with predictable intraoperative and postoperative behavior, researchers must understand how cement formulations affect the polymerization reaction and specially the properties of the end product. In this study, a bioactive filler (commercial hydroxyapatite, HA) was incorporated into poly(methyl methacrylate)‐co‐ethyl hexyl acrylate (PMMA‐co‐EHA) matrices to prepare new bone cement formulations. The new PMMA‐co‐EHA/HA composites were obtained by varying the relative contents of the monomers, MMA, and EHA. The resulting composites were evaluated in terms of the curing parameters, water uptake and weight loss in phosphate buffer solution and mechanical properties. The results obtained showed that incorporation of 25% HA particles induced major changes in the final properties of the bone cements comparing with the unfilled parent matrices. In particular, the peak temperature decreased and the setting time and the bending elastic modulus increased in all formulations containing HA particles. Composites with low EHA content exhibited a decrease in strength after HA incorporation, which was attributed to the poor interfacial adhesion between the components of the composites. Additionally, the immersion results showed that the amount of 25% HA (regarding the total mass) in the composites was not enough to induce in vitro bioactive properties in the materials. POLYM. COMPOS., 35:759–767, 2014. © 2013 Society of Plastics Engineers  相似文献   

3.
Biodegradable starch (Str) polymer was derived from potato, a plant-based natural carbohydrate polymers source, by one-pot synthesis. Hydroxyapatite (HA) was produced from goat bone by step sintering. The inexpensive starch/HA thin film composites were fabricated by customized spin coating. This study revealed that the hydrogen bond energy and distance have significant effect on glass transition temperature of the polymer. The 40 wt % HA contained starch (StrHA40) composite thin film showed excellent tensile strength (3.03 + −0.03 MPa), elongation (21.5 + −5.5%) and modulus (15.5 + −0.2 MPa) closed to human skin. The in vitro swelling and biodegradation kinetics of pristine starch and pure HA has been controlled and improved by using suitable composition. This study postulated the probable water molecule-adsorption mechanisms of pristine starch and starch/HA composite films. The StrHA40 composite showed excellent biocompatibility to the human-blood derived lymphocyte cells. Therefore, the starch/HA thin film composite-based biodegradable scaffolds developed in the present study can be an excellent potential candidate for soft tissue regeneration and/or replacement applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48913.  相似文献   

4.
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   

5.
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   

6.
The nanohydroxyapatite/chitosan/poly(L ‐lactic acid) (HA/CS/PLLA) ternary biocomposites were prepared by blending the hydroxyapatite/chitosan (HA/CS) nanocomposites with poly(L ‐lactic acid) (PLLA) solution. Surface modification by grafting D ‐, L ‐lactic acid onto the HA/CS nanocomposites was designed to improve the bonding with PLLA. The FTIR and 13C‐NMR spectrum confirmed that the oligo(lactic acid) was successfully grafted onto the HA/CS nanocomposites, and the time‐dependent phase monitoring showed that the grafted copolymers were stable. The TEM morphology of the HA/CS/PLLA ternary nanocomposites showed that nano‐HA fibers were distributed homogeneously, compacted closely and wrapped tightly by the CS and PLLA matrix. The ternary biocomposites with the HA content of 60 and 67 wt % exhibited high compressive strength of about 160 MPa and suitable hydrophilicity. The in vitro tests exhibited that the ternary biocomposites have good biodegradability and bioactivity when immersed in SBF solutions. All the results suggested that the n‐HA/CS/PLLA ternary biocomposites are appropriate to application as bone substitute in bone tissue engineering. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

7.
An in situ polymerization with a later solution co‐mixing approach was used in the preparation of polymethyl methacrylate (PMMA) matrix composites using hydroxyapatite (HA) nanoparticles and short carbon fibers(C(f)) as reinforcing materials. The microstructures and fracture surface morphologies of the prepared C(f)/HA‐PMMA composite were characterized using XRD, FTIR, SEM, EDS, and FESEM analyses. The mechanical properties of the composites were tested by a universal testing machine. Results show that the surface of nitric acid‐oxidized carbon fibers and lecithin‐treated HA contain new functional groups. Uniform dispersion of short fibers and HA nanoparticles in PMMA matrix is successfully achieved and the mechanical properties of the composites are obviously improved. The flexural strength, flexural modulus, and Young's modulus of the composites reach the maximum value 128.12 MPa, 1.150 GPa, and 4.572 GPa when carbon fiber and HA mass fraction arrive to 4% and 8%, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

8.
This study related to the preparation of chitosan microspheres by means of reacting chitosan with β‐tricalcium phosphate (β‐TCP) and glutaraldehyde by crosslinking reaction in the oil phase, followed by de‐oil and purification processes to get the product. Three cement composites, Pure P, C1P1, and C2P1, were prepared by the polymerization of poly(methyl methacrylate) (PMMA) bone cement in the presence of 0, 50, and 66.7% chitosan/β‐TCP microspheres, respectively. The result revealed the chitosan/β‐TCP microspheres obtained was in the size range of 50–150 μm. The presence of chitosan/β‐TCP microspheres in the prepared composites decreased the ultimate tensile strength, whereas the modulus remained the same as compared with the commercial PMMA bone cement. Addition of chitosan/β‐TCP microspheres into commercial PMMA cement significantly improved the handling property of the cement paste—that is, the increased setting time and less stickiness behavior of this paste was beneficial, in manipulation, to the operation and easier fittings to the shape and gap of the bony defect and interface. The decreased curing temperature was also less harmful to the surrounding tissues. From scanning electron micrograph observations, chitosan/β‐TCP microspheres can completely mix with bone cement powder and the prepared composites could provide scaffold for osteoblast cells growth and thus improve defects of commercial PMMA bone cement. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3897–3904, 2003  相似文献   

9.
Novel biomineralized hydrogels composed of hyaluronic acid (HA) and vinyl phosphonic acid (VPAc) were designed with the aim of developing a biomimetic hydrogel system to improve bone regeneration by local delivery of a protein drug including bone morphogenetic proteins. We synthesized crosslinked hydrogels composed of methacrylated HA and poly(VPAc) [P(VPAc)], which serves as a binding site for calcium ions during the mineralization process. The HA/P(VPAc) hydrogels were biomineralized by a urea‐mediation method to create functional polymer hydrogels that can deliver the protein drug and mimic the bone extracellular matrix. The water content of the hydrogels was influenced by the HA/P(VPAc) composition, crosslinking density, biomineralization, and ionic strength of the swelling media. All HA/P(VPAc) hydrogels maintained more than 84% water content. Enzymatic degradation of HA/P(VPAc) hydrogels was dependent on the concentration of hyaluronidase and the crosslinking density of the polymer network within the hydrogel. In addition, the release behavior of bovine serum albumin from the HA/PVPAc hydrogels was mainly influenced by the drug loading content, water content, and biomineralization of the hydrogels. In a cytotoxicity study, the HA/P(VPAc) and biomineralized HA/P(VPAc) hydrogels did not significantly affect cell viability. These results suggest that biomineralized HA/P(VPAc) hydrogels can be tailored to create a biomimetic hydrogel system that promotes bone tissue repair and regeneration by local delivery of protein drugs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41194.  相似文献   

10.
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   

11.
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   

12.
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   

13.
First, making from eucalyptus cellulose fiber, the influences of different compound enzymolysis conditions on the morphology of cellulose nanocrystals (CNCs) were studied. Under the actions of the compound enzyme composed of cellulase and xylanase with the concentration ratio of 9:1, total enzyme concentrations of 10 and 500 U mL−1 and the hydrolysis time of 12 and 5 h, the rod-like CNCs (length 600 nm, width 30 nm) and the spherical CNCs (40 nm) were obtained, respectively. Subsequently, the crystallinities, chemical structures, and thermal stabilities of the rod-like and spherical CNCs revealed that, the CNCs structures were still similar to those of the eucalyptus cellulose fiber, the thermal decomposition temperatures of the rod-like and spherical CNCs (345, 343 °C) were a little lower than that of the eucalyptus cellulose fiber (364 °C). Lastly, the control mechanism of CNC morphology by the compound enzymatic hydrolysis was also discussed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48407.  相似文献   

14.
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   

15.
Abstract

The 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   

16.
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   

17.
A crosslinked amphiphilic copolymer [poly(ethylene glycol) (PEG)–poly(methyl methacrylate) (PMMA)–ethylene glycol dimethacrylate (EGDM)] composed of PMMA, PEG, and crosslinking units (EGDM) was synthesized by atom transfer radical polymerization to develop micelles as carriers for hydrophobic drugs. By adjusting the molar ratio of methyl methacrylate and EGDM, three block copolymer samples (P0, P1, and P2) were prepared. The measurement of gel permeation chromatography and 1H‐NMR indicated the formation of crosslinked structures for P1 and P2. Fluorescence spectroscopy measurement indicated that PEG–PMMA–EGDM could self‐assemble to form micelles, and the critical micelle concentration values of the crosslinked polymer were lower than those of linear ones. The prepared PEG–PMMA–EGDM micelles were used to load doxorubicin (DOX). The drug‐loading efficiencies of P1 and P2 were higher than that of P0 because the crosslinking units enhanced the micelles' stability. With increasing drug‐loading contents, DOX release from the micelles in vitro was decreased, and in the crosslinked formulations, the release rate was also slower. An in vitro release study indicated that DOX release from the micelles for the linear samples was faster than that for crosslinked micelles. The drug feeding amount increased and resulted in an increase in the drug‐loading content, and the loading efficiency decreased. These PEG–PMMA–EGDM micelles did not show toxicity in vitro and could reduce the cytotoxicity of DOX in the micelles; this suggested that they are good candidates as stable drug carriers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39623.  相似文献   

18.
Abstract

The 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   

19.
郭效军  李岱 《硅酸盐通报》2017,36(1):345-351
采用化学沉淀法,在模拟体液环境中制备了Na、Mg、F三元素共掺杂的羟基磷灰石( HA)粉体,利用XRD、FT-IR、SEM、EDS等技术对其物相结构、微观形貌、化学组成和热稳定性进行了分析和表征。结果表明:Na/Mg/F对HA进行掺杂引起HA晶格发生畸变。 F元素的掺杂量对HA的形貌具有一定的影响;随着F掺杂量的增加,球形的HA颗粒逐渐转变成棒状结构。 F/P=0.25时,可以制得小而均匀的HA颗粒。抑菌环实验表明Na/Mg/F共掺杂HA对金黄色葡萄球菌的生长具有一定的抑制作用。 F/P=0.25时,抗菌性最强。煅烧温度在1000℃时HA的物相未发生变化,说明样品具有良好的热稳定性。  相似文献   

20.
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.

TEM images of an OA‐clay/PMMA composite.  相似文献   


设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号