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1.
Polycaprolactone (PCL) is a bioresorbable and biocompatible polymer that has been widely used in long-term implants and controlled drug release applications. However, when it comes to tissue engineering, PCL suffers from some shortcomings such as slow degradation rate, poor mechanical properties, and low cell adhesion. The incorporation of calcium phosphate-based ceramics and bioactive glasses into PCL has yielded a class of hybrid biomaterials with remarkably improved mechanical properties, controllable degradation rates, and enhanced bioactivity that are suitable for bone tissue engineering. This review presents a comprehensive study on recent advances in the fabrication and properties of PCL-based composite scaffolds containing calcium phosphate-based ceramics and bioglasses in terms of porosity, degradation rate, mechanical properties, in vitro and in vivo biocompatibility and bioactivity for bone regeneration applications. The fabrication routes range from traditional methods such as solvent casting and particulate leaching to novel approaches including solid free-form techniques. 相似文献
3.
Fluoroapatite containing glass-ceramics were prepared from Li 2O-CaO-CaF 2-P 2O 5-SiO 2 system. The glass was melted at 1480°C for 1 h. The object of observation was the preparing crystal phase of fluoroapatite
in amorphous glass matrix. The morphology of lithium disilicate glass-ceramics was studied by SEM. The crystal growth and
thermal properties of fluoroapatite were studied by X-ray diffraction and DTA. The more the content of P 2O 5, the more the presence of fluoroapatite particles. SEM investigation clearly indicated the phase separation and formation
of a primary crystalline phase of fluoroapatite in the studied glass-ceramics. DTA curves of the fluoroapatite samples exhibit
exothermic effects in the temperature range 337-694°C depending on the composition of the materials. The position of exothermic peak for lithium disilicate on DTA curves moves with increasing specific surfacetowards lower temperatures which points on its preferential surface crystallization. As far as physical qualities are concerned,
mainly color and gloss, the best qualities of all observed materials belong to glass-ceramics with 10% P 2O 5.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Hydrogels are widely used for controlled delivery of therapeutic agents. However, hydrogels lack bioactivity to encourage bone formation and mechanical integrity. Moreover, chemically crosslinked hydrogels exhibit cytotoxic effect. To overcome these limitations poly‐vinyl alcohol (PVA) and poly‐acrylic acid (PAA) blends were combined with ceramic materials based on β tricalcium phosphate, wollastonite, and magnesium silicate with different pore size distributions. The final 3D matrix was physically crosslinked using various freeze thawing (F/T) cycles. FTIR and SEM analysis showed that ceramics were dispersed within the polymer matrix and formed hydrogen bonds. Swelling studies in buffer solution pH 7.4 showed an increase in polymer swelling when ceramic was added. Furthermore, rheological testing demonstrated that incorporation of ceramics caused an increase in mechanical properties which varies with different pore size distributions of ceramics grains added. DSC thermograms showed increased T g values for samples containing ceramics. Antimicrobial activity containing ciprofloxacin was tested against a pathogen associated with osteomyelitis and presented positive results with ciprofloxacin. The combination of increased strength and ability to encapsulate a clinically relevant antimicrobial agent indicates that the composite tested in this study has potential for the treatment of osteomyelitis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 761–773 相似文献
5.
Abstract Two types of glass-ceramics have been developed in the system of calcium phosphate without silica. The preparation conditions, crystallization processes, and some of physical properties are briefly reported. These glass-ceramics have high potential use for bone substitutes and dental materials such as dental crown, root and tooth. 相似文献
6.
In this work we present experimental results about synthesis, structure evolution and in vitro bioactivity of new calcium phosphate silicate/wollastonite (CPS/W) glass-ceramics. The samples obtained were synthesized
via polystep sol-gel process with different Ca/P+Si molar ratio (R). The structure of the materials obtained was studied by
XRD, FTIR spectroscopy and SEM. XRD showed the presence of Ca 15(PO 4) 2(SiO 4) 6, β-CaSiO 3 and α-CaSiO 3 for the sample with R=1.89 after thermal treatment at 1200°C/2h. The XRD results are in good agreement with FTIR analysis.
SEM denotes that apatite formation can be observed after soaking in simulated body fluid (SBF).
相似文献
7.
采用高分子网络凝胶法合成出SiO2-CaO-P2O5生物玻璃陶瓷,该材料具有较低含硅量和高钙磷比(nCa/nP=1.57)的特点,更接近人体硬组织的成分。将材料在SBF溶液浸泡研究材料的体外生物活性,通过TG/DTA,XRD,FTIR和SEM等方法对粉体和浸泡后的样品表面进行表征,ICP-AES对SBF溶液中钙、磷、硅离子的浓度进行检测。结果表明,氧化硅的添加有利于玻璃陶瓷表面磷灰石晶相的形成;随着浸泡时间的延长,沉积在样品表面的碳酸羟基磷灰石层逐渐由球型突起变为叶片状,溶液中钙、磷离子浓度降低,而硅离子浓度增加,说明材料具有良好的生物活性,适宜作为牙齿和骨骼的替代或修复材料。 相似文献
8.
The problems of synthesis and study of the physicochemical properties of graphite intercalation compounds (GIC) formed upon
insertion of various molecules into the interplanar space of graphite are considered. Binary and ternary intercalation compounds
with protonic acids (HNO 3, CH 3COOH, H 3PO 4, H 2SO 4, etc.) are described. The results of systematic research into graphite intercalation by potentiometry, calorimetry, powder X-ray
diffraction, conductivity measurements, DTA, chemical analysis, and other methods are given. These results underlie elucidation
of the characteristic and peculiar features of acid insertion into graphite. The physicochemical properties and practical
applications of GIC and low-density carbon materials are analyzed.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1699–1716, August, 2005. 相似文献
9.
This review is focused on the analysis of experimental results on oxygen ion-conducting ceramic materials based on HfO 2, CeO 2, and ThO 2, published in the former Soviet Union. In particular, the physicochemical and transport properties of fluorite-related oxides
and the characteristics of electronic conduction in these solid electrolytes are briefly reviewed. Emphasis is given to electrocatalytic
and electrochemical properties of cerium-containing oxides, which are promising materials for electrodes of electrochemical
cells operating in reducing atmospheres, and mixed-conducting membranes. A comparative analysis of specific features of the
solid-electrolyte ceramics based on hafnia, zirconia, ceria, and thoria is performed in order to reveal basic tendencies of
oxygen ionic transport in fluorite-type oxides, and to identify the potential applicability of these materials in various
high-temperature electrochemical devices.
Received: 23 September 1999 / Accepted: 10 October 1999 相似文献
10.
The methods for preparation of highly transparent optical ceramics based on simple and complex fluoride compounds of elements
of the first, second, and third Group in the Periodical system are considered. The use of precursors as nanopowders and processes
of their self-assembling on heating results in maximally homogeneous, transparent, and mechanically strong ceramics. The resulting
calcium fluoride ceramics possess optical losses of 10 −2–10 −3 cm −1 at 1.06 μm and shock resistance characterized by the fracture toughness K
1C
= 4.7±0.3 MPa m 1/2 (for comparison, for a calcium fluoride single crystal K
1C
= 1.5±0.15 MPa m 1/2). Regularities of the chemistry of fluoride nanopowders were considered in comparison with the oxide nanopowders: the fluorides
are prone to hydrolysis, and powder nanoparticles precipitated from aqueous solutions have complex and heterogeneous (over
the volume) chemical composition. The spectral luminescence properties of the ceramics activated by rare-earth metals (Ce 3+, Nd 3+, Er 3+, Yb 3+) or containing active color centers are presented. The generation properties of the lithium fluoride ceramics with the color
centers and the ternary Ca-Sr-Yb fluoride during diode laser pumping are describe
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 863–872, May, 2008. 相似文献
12.
Hydroxyapatite is an elective material for bone substitution. In this outline of our recent activity the crucial role of nanostructured ceramics in the design and preparation of ceramic scaffolds will be described, focussing on our more recent interest in biomimetic apatites, in particular apatites containing HPO 42– CO 32– and Mg 2+ which are similar to the mineral component of bone. The paper describes such nanostructured products and, in particular, innovative synthetic techniques capable of yielding powders with higher reactivity and bioactivity. However, so far the characteristics of artificial bone tissues have been shown to be very different from those of natural bone, mainly because of the absence of the peculiar self-organizing interaction between apatites and the protein component. This causes modification of the structure of apatites and of the features of the overall composite forming human bone tissue. Therefore, attempts to mimic the features and structure of natural bone tissue, leading toward so-called bio-inspired materials, will be speculated upon. New techniques used to reproduce a composite in which a nanosize blade-like crystal of hydroxyapatite (HA) grows in contact with self-assembling fibres of natural polymer will be presented. In this specific case, the amazing ability of biological systems to store and process information at the molecular level, nucleating nanosize apatites (bio-inspired material), is exploited. 相似文献
13.
Crystallization, morphology and mechanical properties of a spodumene-diopside glass ceramics with adding different amount
of CaO and MgO in Li 2O-Al 2O 3-2SiO 2 were investigated. With CaO and MgO addition, the crystallization temperature ( T
p) decreased, the value of Avrami constant ( n) decreased from 3.2±0.3 to 1.4±0.2, the activation energy ( E) increased from 299±3 kJ mol −1 to 537±5 kJ mol −1. The crystalline phases precipitated were h-quartz solid solution, β-spodumene and diopside. The mechanism of crystallization of the glass ceramics changed from bulk
crystallization to surface crystallization. The grain sizes and thermal expansion coefficients increased while flexural strength
and fracture toughness of the glass-ceramics increased first, and then decreased. The mechanical properties were correlated
with crystallization and morphology of glass ceramics. 相似文献
14.
The preparation and physicochemical properties of salts of dinitramide HN(NO 2) 2 with uni- and bivalent metals of groups I, II, VII, and VIII of the Periodic Table are considered.For part 2,see Russ. Chem. Bull., 1994, 43, 1200.Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1546–1549, September, 1994. 相似文献
15.
The designed molecular structures have been subjected to computational analysis for calculating their physicochemical properties and drug likeness. The calculated data indicate that most of the compound possess the bioactivity score in the active zone. Synthetic approach to the target compounds is straightforward and easy to handle. Structures of the new compounds are supported by FT-IR, 1H, and 13C NMR, and mass spectra. Antimicrobial tests of the products against pathogens (S. aureus, S. epidermidis, E. coli, and P. mirabilis) indicate the products as active or highly active. Their cyto-toxicity is determined to be 92–98% at concentration of 3.125 µmol/L. The molecular docking analysis carried out for the target compounds against the receptor Glc-N-6P exhibits low binding energy and various binding sites of those. 相似文献
16.
In previous
works, the effects on the devitrification mechanism of a certain composition
calcium phosphate with additives of TiO 2, SiO 2,
Al 2O 3, CeO 2
have been studied. It was found that some metal oxide additives played a key
role as the nucleation agent in calcium phosphate glass-ceramics, and the
devitrification mechanism of calcium phosphate glass system was changed drastically
by addition such as metal oxide. Hydroxyapatite (HAp), tricalcium phosphate
(TCP) and β-calcium phosphate (β-CaP 2O 6)
whisker are the three most biologically compatible materials to human bone
in bio-ceramics field. In this work, the effect on devitrification mechanism
and the physical properties of certain composition calcium phosphate glass
with three above additives were investigated, and the result shown that although
no fine crystalline was induced in the certain composition of calcium phosphate
glass when a large amount of additive was added, but such additives play a
catalyst role by lowering the activation energies of devitrification. It would
supplement the mechanical properties and the biocompatibility for the calcium
phosphate glasses. 相似文献
17.
Polyetheretherketone (PEEK) is a popular polymeric biomaterial which is primarily used as an intervertebral spacer in spinal fusion surgery; but it is developed for trauma, prosthodontics, maxillofacial, and cranial implants. It has the purported advantages of an elastic modulus which is similar to native bone and it can be easily formed into custom 3D shapes. Nevertheless, PEEK's disadvantages include its poor antibacterial resistance, lack of bioactivity, and radiographic transparency. This study presents a simple approach to correcting these three shortcomings while preserving the base polymer's biocompatibility, chemical stability, and elastic modulus. The proposed strategy consists of preparing a PEEK composite by dispersing a minor fraction (i.e., 15 vol%) of a silicon nitride (Si 3N 4) powder within its matrix. In vitro tests of PEEK composites with three Si 3N 4 variants—β‐Si 3N 4, α‐Si 3N 4, and β‐SiYAlON—demonstrate significant improvements in the polymer's osteoconductive versus SaOS‐2 cells and bacteriostatic properties versus gram‐positive Staphylococcus epidermidis bacteria. These properties are clearly a consequence of adding the bioceramic dispersoids, according to chemistry similar to that previously demonstrated for bulk Si 3N 4 ceramics in terms of osteogenic behavior (vs both osteosarcoma and mesenchymal progenitor cells) and antibacterial properties (vs both gram‐positive and gram‐negative bacteria). 相似文献
18.
Current materials used for bone regeneration are usually bioactive ceramics or glasses. Although they bond to bone, they are brittle. There is a need for new materials that can combine bioactivity with toughness and controlled biodegradation. Sol‐gel hybrids have the potential to do this through their nanoscale interpenetrating networks (IPN) of inorganic and organic components. Poly(γ‐glutamic acid) (γ‐PGA) was introduced into the sol‐gel process to produce a hybrid of γ‐PGA and bioactive silica. Calcium is an important element for bone regeneration but calcium sources that are used traditionally in the sol‐gel process, such as Ca salts, do not allow Ca incorporation into the silicate network during low‐temperature processing. The hypothesis for this study was that using calcium methoxyethoxide (CME) as the Ca source would allow Ca incorporation into the silicate component of the hybrid at room temperature. The produced hybrids would have improved mechanical properties and controlled degradation compared with hybrids of calcium chloride (CaCl 2), in which the Ca is not incorporated into the silicate network. Class II hybrids, with covalent bonds between the inorganic and organic species, were synthesised by using organosilane. Calcium incorporation in both the organic and inorganic IPNs of the hybrid was improved when CME was used. This was clearly observed by using FTIR and solid‐state NMR spectroscopy, which showed ionic cross‐linking of γ‐PGA by Ca and a lower degree of condensation of the Si species compared with the hybrids made with CaCl 2 as the Ca source. The ionic cross‐linking of γ‐PGA by Ca resulted in excellent compressive strength and reduced elastic modulus as measured by compressive testing and nanoindentation, respectively. All hybrids showed bioactivity as hydroxyapatite (HA) was formed after immersion in simulated body fluid (SBF). 相似文献
19.
Features of the adsorption of phosphatidylcholine (PCh) by inorganic silicon-containing materials with various degrees of order (MCM-41, MMC-1, and silica gel) from solutions in hexane under equilibrium conditions in the temperature range of 283–323 K are considered. It is found that the adsorption of the phospholipid within the C
e
= (0.6–4.0) × 10–4 mmol/dm3 range of concentrations on the investigated materials is characterized by monomolecular absorption. Differential thermodynamic characteristics (ΔG, ΔH, and ΔS) of the sorption of PCh by silicon-containing materials with various degrees of order in the temperature range of 283–323 K are considered. An increase in the affinity of silicon-containing materials toward the phospholipid upon an increase in the temperature of the sorption process is observed. 相似文献
20.
The formation of mesoporous mesophase materials via precipitation of soluble SiO 2 forms on the surface of cationic cetyltrimethylammonium micelles was studied. The main physicochemical factors determining
the formation of siliceous mesoporous materials and providing an explanation of the observed changes in the structural and
textural characteristics of the materials were identified and discussed.
Translated from Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1845–1851, October, 1999. 相似文献
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