Synthesis and characterization of nano-HA/PA66 composites

Based on the bioactivity and biocompatibility of hydroxyapatite (HA) and the excellent mechanical performance of polyamide 66 (PA66), a composite of nanograde HA with PA66 was designed and fabricated to mimic the structure of biological bone which exhibits a composite of nanograde apatite crystals and natural polymer. The HA/PA66 composite combines the bioactivity of HA and the mechanical property of PA66. This study focused on the preparation method of HA/PA66 composite and the influence of HA crystals on the characterization of the composite. HA slurry was used directly to prepare HA/PA66 composite by a solution method, in which HA is able to form hydrogen bond, i.e. chemical bonding with PA66. The nano-HA needle-like crystals treated by hydrothermal method are better in the particle size distribution and the particle dispersion. The morphology, crystal structure and crystallinity as well as crystal size of these needle-like crystals are similar to bone apatite. The nano-HA needle-like crystals dispersed uniformly in PA66 matrix with reinforcement effect and can prevent the micro-crackle spreading into cleft and fracture during the deformation process. The mechanical testing shows that the nano-HA/PA66 composite has a good mechanical property, and may be a promising bone replacement material.     

Synthesis and characterization of hydroxyapatite/chitosan nanocomposite materials for medical engineering applications

Incorporation of hydroxyapatite (HA) with organic polymer in favor of composites would be used in biomaterial engineering. According to prior researches, because of its chemical similarity to natural bone and dental, this product could improve bioactivity and bone bonding ability. In this research, nano-hydroxyapatite/chitosan composite material was prepared via in situ Hybridization route. The surface chemical characterization on the nanocomposite was evaluated by Fourier transformed infrared (FTIR) and X-ray diffraction (XRD). Surface topography, roughness and morphology of the samples were observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The characterization results confirmed homogeneity, interaction and integration between the HA and chitosan matrix. It was indicated that composite samples consist of homogeneous aggregations around 40–100 nm, in which many HA nanocrystals align along the chitosan molecules. HA grain gradually decreased in size when amount of chitosan increased from 0 to 6 g into 100 cc solution. It can be seen that by increasing chitosan, the aggregation of nanoparticles enhance and subsequently, improve the expected compatibility among HA filler and chitosan matrix. Furthermore, the mechanical compressive testing indicated that the synthesized composites have acceptable mechanical behavior for tissue substitution. The mechanistic of the biodegradable nanocomposite systems, their preparation and characterization for medical usage are strongly discussed.     

纳米羟基磷灰石/壳聚糖/羧甲基纤维素三元复合骨修复材料的制备和性能研究

用溶液共混法在常温常压下制备了不同比例的纳米羟基磷灰石/壳聚糖/羧甲基纤维素三元复合骨修复材料.用燃烧实验、IR、XRD、SEM及TEM对复合材料的组成结构及形貌进行了分析和观察,并初步研究了其力学性能.结果表明该复合材料中纳米羟基磷灰石均匀分散在壳聚糖和羧甲基纤维素网络结构中,三组分间还产生了一定的相互作用,其形态、尺寸及结构与自然骨类似,且其抗压强度比纳米羟基磷灰石/壳聚糖二元复合材料更高;同时,通过调节各组分比例,可制得不同抗压强度的复合材料.因此,该三元复合材料可望作为一种新型可降解的非承重部位骨修复材料,在生物医学材料的研究中具有重要意义.     

Hybrid composite scaffolds prepared by sol–gel method for bone regeneration

This study reports the synthesis and characterization of hydroxyapatite (HA)/polycaprolactone (PCL) hybrid composite materials synthesized by sol–gel method. The fabrication of scaffolds was performed by salt-leaching technique using NaCl as porogen agent. In the first step, the physico-chemical characterization of composite material was performed to evaluate the composition and the interaction between the organic/inorganic phases. In the second step, optimized scaffolds were bioactivated on the surface. The combined effect of scaffold morphology and surface bioactivity is ideal for bone tissue engineering, supporting bone cells adhesion, proliferation and differentiation. Here, a combined strategy involving biomimetic approach, using a supersaturated Simulated Body Fluid (SBF), and salt-leaching technique has been developed to grow hydroxyapatite in composite scaffolds able to regenerate the natural bone.     

Synthesis and characterization of mechanically strong carboxymethyl cellulose–gelatin–hydroxyapatite nanocomposite for load-bearing orthopedic application

Novel three-dimensional hybrid polymer–hydroxyapatite nanocomposites have been developed as load-bearing synthetic bone graft through in situ mineralization process, using natural polymers carboxymethyl cellulose (CMC) and gelatin (Gel) as matrix. This process is simple and does not involve any chemical cross-linker. Detailed structural and physicochemical characterization of the samples disclosed that incorporation of gelatin with CMC assists the formation of CMC-Gel polymeric network of new conformational structure through non-covalent interactions (H-bond). The formation of hydroxyapatite (HA) in this polymeric network was occurred in such a fashion that the HA serves as bridging molecule which strengthen the polymeric network more and formed a mechanically strong three-dimensional CMC-Gel-HA nanocomposite. The synthesized CMC-Gel-HA nanocomposites have compressive strength and modulus in the range of 40–86 MPa and 0.4–1.2 GPa, respectively, analogous to human cancellous as well as cortical bone. In vitro cell interaction of the synthesized nanocomposites with osteoblast-like MG-63 cells has been evaluated. Results showed that synthesized CMC-Gel-HA nanocomposite promote cells for high alkaline phosphatase activity and extracellular mineralization. Extracellular mineralization ability of nanocomposite was investigated by alizarin red staining and von Kossa staining. Biodegradable nature and bone apatite formation ability of CMC-Gel-HA nanocomposite under simulated physiological environment were investigated by different characterization processes. Results indicated that the synthesized CMC-Gel-HA nanocomposite has great potential to be used as regenerative bone graft in major load-bearing region.     

Preparation and properties of a novel bone repair composite: nano-hydroxyapatite/chitosan/carboxymethyl cellulose

Nano-hydroxyapatite/chitosan/carboxymethyl cellulose (n-HA/CS/CMC) composites with weight ratios of 70/10/20, 70/15/15 and 70/20/10 were prepared through a co-solution method. The properties of the composites were characterized by means of burn-out test, IR, XRD, TEM and universal material testing machine. The degradation and bioactivity were also investigated by in vitro test in a simulated body fluid (SBF) for 8 weeks. The results showed that n-HA particles were dispersed uniformly in organic phase, and strong chemical interactions formed among the three phases. Moreover, the composites were similar to natural bone in morphology and size. In addition, the compressive strength was improved compared with n-HA/CS composite. The biodegradation rate was controllable by altering weight ratio of the CS/CMC. Meanwhile, the composites could induce apatite particles to deposit in SBF. All the above results indicate that the novel composites of n-HA/CS/CMC have a promising prospect used for bone repair materials in view of the good mechanical property, adjustable biodegradation rate and bioactivity in SBF. Additionally, the study would provide a good guide to exploit clinical application of natural cellulose.     

Possibilities and limitations of preparing silica/collagen/hydroxyapatite composite xerogels as load-bearing biomaterials

The combination of silica and collagen was identified in natural composites and recently recognized to be a valuable system for the preparation of innovative biomaterials for bone substitution applications. The present study reports on the development of silica/collagen composites, investigation of the underlying formation processes as well as further interactions with hydroxyapatite as a third phase. The possibilities and limitations of the material concept based on the sol-gel strategy were screened and characteristic composition ranges were identified. The gelation determining the processing time is strongly linked to the pH of silicic acid and collagen suspension mixtures as well as the buffer used and collagen concentration. The templating activity of collagen for silica formation is driven by primary amine groups as suggested by biochemical analysis and scanning electron microscopy. A high solid concentration in the initial hydrogels is essential in order to maintain the sample shape during transformation into monolithic and compact xerogels. The presence of fibrillar collagen significantly enhances the compressive strength of the xerogels up to 200 MPa and strain to fracture of up to 11%. The modular concept of the composite xerogel formation process allows incorporation of further phases such as calcium phosphate phases or prospectively drugs for the treatment of local or systemic diseases, opening large perspectives for the development of multifunctional bone implants.     

氧化锑/高岭土复合阻燃微粉的湿化学法制备及特性

采用湿化学法制备了氧化锑 /高岭土复合阻燃微粉 ,用热重 (TG)、差示扫描量热法 (DSC)对其阻燃特性进行了分析 ,用SEM分析了粒子形貌 ,激光光散射粒度分布仪分析了粒子的分布情况。热分析结果表明 ,与球磨法相比 ,湿化学法制备的样品的失重量大、失重温度范围广、放热峰范围广 ;化学法制备复合微粉的反应活化能与球磨法相差不大。SEM分析及粒度分析表明 :复合微粉大多处于 0 .2 0 μm以下 ,化学法制备的样品中以锑白粉为主 ,高岭土附在锑白粉表面 ,充分与锑白粉发生物理、化学作用。同时发现 ,样品6 0 0℃热处理 2h后 ,粒子结合更加紧密     

HA and double-layer HA-P2O5/CaO glass coatings: influence of chemical composition on human bone marrow cells osteoblastic behavior

Human osteoblastic bone marrow derived cells were cultured for 28 days onto the surface of a glass reinforced hydroxyapatite (HA) composite and a commercial type HA plasma sprayed coatings, both in the as-received condition and after an immersion treatment with culture medium during 21 days. Cell proliferation and differentiation were analyzed as a function of the chemical composition of the coatings and the immersion treatment.Cell attachment, growth and differentiation of osteoblastic bone marrow cells seeded onto as-received plasma sprayed coatings were strongly affected by the time-dependent variation of the surface structure occurring during the first hours of culture. Initial interactions leading to higher amounts of adsorbed protein and zeta potential shifts towards negative charges appeared to result in surface structures with better biological performance. Cultures grown onto the pretreated coatings showed higher rate of cell proliferation and increased functional activity, as compared to those grown onto the corresponding as-received materials. However, the cell behavior was similar in the glass composite and HA coatings.The results showed that the glass composites present better characteristics for bone cell growth and function than HA. In addition, this work also provide evidence that the biological performance of the glass composites can be modulated and improved by manipulations in the chemical composition, namely in the content of glass added to HA. © 2001 Kluwer Academic Publishers     

Evaluation of Injectable Composite Material Comprising Biphasic Bone Substitutes and Crosslinked Collagen

Bone tissue engineering has emerged as a promising approach to regenerate bone tissue, and injectable biomaterials have shown potential for bone regeneration applications due to their ease of administration and ability to fill irregularly shaped defects. This study aims to develop and characterize an injectable composite material comprising biphasic bone substitutes (BBS) and crosslinked porcine collagen type I for bone regeneration applications. The collagen is crosslinked via a UVA-riboflavin crosslinking strategy and evaluated by testing the physicochemical properties, including the rheological behavior, dynamic storage modulus (G′) and loss modulus (G″), and in vitro degradation process. The results show that the crosslinked collagen (xCol) exhibits suitable physicochemical properties for injectability and improved viscoelasticity and degradation resistance. Furthermore, xCol is then combined with BBS in a predetermined ratio, obtaining the injectable composite material. The biocompatibility of the materials is evaluated in vitro by XTT and BrdU assays on fibroblasts and preosteoblasts. The results demonstrate that the composite material is biocompatible and supporting pre-osteoblasts proliferation. In conclusion, the injectable composite material BBS-xCol has promising physiochemical and biological properties for bone regeneration applications. Further studies are warranted to evaluate its efficacy in vivo and optimize its composition for clinical translation.     

Characterization of a novel natural cellulose fabric from Manicaria saccifera palm as possible reinforcement of composite materials

Identifying novel natural fibers/fabrics with proper properties as reinforcement material is a new challenge in the field of bio-composites. Hence, the aim of this paper is to study the possibility of using a natural fabric extracted from Manicaria saccifera palm as a novel reinforcement in composites. This fabric was extensively characterized by chemical composition analysis, infrared spectroscopy (FTIR) analysis, morphological studies (SEM), thermo-gravimetric analysis (TGA) and physical /mechanical properties studies. From SEM analysis it was identified globular protrusions spread uniformly over the fiber which could help the mechanical interlock with the resin. As well, Manicaria fabric showed good thermal stability, low density, low moisture content and good tensile properties. Further, their properties are comparable to most natural cellulose fabrics and some synthetic fabrics, such as fiber glass fabrics. Manciaria saccifera fabric showed to be a suitable candidate as natural reinforcement material for the development of bio- composite.     

n-HA/PA66/HDPE复合生物材料的制备和性能研究

应用纳米羟基磷灰石(n-HA)、聚酰胺66(PA66)和高密度聚乙烯(HDPE)制备了生物医用复合材料。用化学分析法、燃烧实验、热分析、AFM、IR、XRD对复合材料的组成和结构进行了分析,并对复合材料的力学性能进行了研究。结果表明所制备的复合材料组成均一,具有高强柔韧的力学性能,纳米羟基磷灰石、聚酰胺66、高密度聚乙烯三者之间产生了一定的相互作用,形成了稳定的界面结合。因此,该三元复合材料可能成为一种新型的骨修复材料,在生物医学材料的开发和应用研究中具有重要意义。     

A study on the structure and mechanical behavior of the Terrapene carolina carapace: A pathway to design bio-inspired synthetic composites

The multiscale structure, materials properties, and mechanical responses of the turtle shell (Terrapene carolina) were studied to understand the fundamental knowledge of naturally occurring biological penetrator-armor systems. The structure observation and chemical analysis results revealed that the turtle shell carapace comprises a multiphase sandwich composite structure of functionally graded material having exterior bone layers and a foam-like bony network of closed-cells between the two exterior bone layers. Although the morphology was quite different, the exterior bone layers and interior bony network possessed comparable hardness and elastic modulus values of ~ 1 GPa and ~ 20 GPa, respectively. Compression and flexure test results showed a typical nonlinear deformation behavior recognizant of man-made foams. The mechanical test results revealed that the interior closed-cell foam layer plays a significant role on the overall deformation behavior of the turtle shell. The finite element analysis simulation results showed comparable agreement with the actual experimental test data. This systematic study could provide fundamental understanding for structure-property phenomena and biological pathways to design bio-inspired synthetic composite materials.     

Needle-like nano hydroxyapatite/poly(l-lactide acid) composite scaffold for bone tissue engineering application

In this paper, a new nano-hydroxyapatite / poly (l-lactide acid) (nHAP/PLLA) composite scaffold comprising needle-like nHAP particles was prepared. In the first step, the identification and morphology of chemically synthesized HAP particles were determined by XRD, EDX, FTIR and SEM analyses. The needle-like nHAP particles with an average size of approximately 30–60 nm in width and 100–400 nm in length were found similar to needle-like bone nano apatites in terms of chemical composition and morphology. In the second step, nHAP and micro-sized HAP (mHAP) particles were used to fabricate HAP filled PLLA (HAP/PLLA) composites scaffolds using solid–liquid phase separation method. The porosity of scaffolds was up to 85%, and their average macropore diameter was in the range of 64–175 µm. FTIR and XRD analyses showed the presence of molecular interactions and chemical linkages between HAP particles and PLLA matrix. The compressive strength of nanocomposite scaffolds could high up to 8.46 MPa while those of pure PLLA and microcomposite scaffolds were 1.79 and 4.61 MPa, respectively. The cell affinity and cytocompatibility of the nanocomposite scaffold were found to be higher than those of pure PLLA and microcomposite scaffolds. Based on the results, the newly developed nHAP/PLLA composite scaffold is comparable with cancellous bone in terms of microstructure and mechanical strength, so it may be a suitable alternative for bone tissue engineering applications.     

Relevance of the sterilization-induced effects on the properties of different hydroxyapatite nanoparticles and assessment of the osteoblastic cell response

Hydroxyapatite (Hap) is a calcium phosphate with a chemical formula that closely resembles that of the mineral constituents found in hard tissues, thereby explaining its natural biocompatibility and wide biomedical use. Nanostructured Hap materials appear to present a good performance in bone tissue applications because of their ability to mimic the dimensions of bone components. However, bone cell response to individual nanoparticles and/or nanoparticle aggregates lost from these materials is largely unknown and shows great variability. This work addresses the preparation and characterization of two different Hap nanoparticles and their interaction with osteoblastic cells. Hap particles were produced by a wet chemical synthesis (WCS) at 37°C and by hydrothermal synthesis (HS) at 180°C. As the ultimate in vivo applications require a sterilization step, the synthesized particles were characterized ‘as prepared’ and after sterilization (autoclaving, 120°C, 20 min). WCS and HS particles differ in their morphological (size and shape) and physicochemical properties. The sterilization modified markedly the shape, size and aggregation state of WCS nanoparticles. Both particles were readily internalized by osteoblastic cells by endocytosis, and showed a low intracellular dissolution rate. Concentrations of WCS and HS particles less than 500 μg ml⁻¹ did not affect cell proliferation, F-actin cytoskeleton organization and apoptosis rate and increased the gene expression of alkaline phosphatase and BMP-2. The two particles presented some differences in the elicited cell response. In conclusion, WCS and HS particles might exhibit an interesting profile for bone tissue applications. Results suggest the relevance of a proper particle characterization, and the interest of an individual nanoparticle targeted research.     

Nano/Micro‐Manufacturing of Bioinspired Materials: a Review of Methods to Mimic Natural Structures

Through billions of years of evolution and natural selection, biological systems have developed strategies to achieve advantageous unification between structure and bulk properties. The discovery of these fascinating properties and phenomena has triggered increasing interest in identifying characteristics of biological materials, through modern characterization and modeling techniques. In an effort to produce better engineered materials, scientists and engineers have developed new methods and approaches to construct artificial advanced materials that resemble natural architecture and function. A brief review of typical naturally occurring materials is presented here, with a focus on chemical composition, nano‐structure, and architecture. The critical mechanisms underlying their properties are summarized, with a particular emphasis on the role of material architecture. A review of recent progress on the nano/micro‐manufacturing of bio‐inspired hybrid materials is then presented in detail. In this case, the focus is on nacre and bone‐inspired structural materials, petals and gecko foot‐inspired adhesive films, lotus and mosquito eye inspired superhydrophobic materials, brittlestar and Morpho butterfly‐inspired photonic structured coatings. Finally, some applications, current challenges and future directions with regard to manufacturing bio‐inspired hybrid materials are provided.     

A study on nano-composite of hydroxyapatite and polyamide

A new kind of nano-composite of nano-hydroxyapatite (n-HA) and polyamide₈₀₆₃ (PA) was prepared directly using nano-hydroxyapatite slurry and co-solution method under normal atmospheric pressure. The results show that the n-HA content in the composite can reach 65 wt%, similar to the apatite content in natural bone. Interface chemical bonding forms between n-HA and polyamide, the n-HA keeps the original morphological structure with a crystal size of 10–30 nm in diameter by 50–90 nm in length with an aspect ratio of 2.5, and distributes uniformly in the composite. The synthetic nano-composite could be one of the best bioactive materials for load-bearing bone repair or substitution.     

TiO2/bone composite materials for the separation of heavy metal impurities from waste water solutions

Pure bone material obtained from cow meat, as apatite-rich material, and TiO₂-bone composite materials are prepared and studied to be used for heavy metal ions separation from waste water solutions. Meat wastes are chemically and thermally treated to control their microstructure in order to prepare the composite materials that fulfill all the requirements to be used as selective membranes with high performance, stability and mechanical strength. The prepared materials are analyzed using Hg-porosimetry for surface characterization, energy dispersive X-ray spectroscopy (EDAX) for elemental analysis and Fourier transform infrared spectroscopy (FTIR) for chemical composition investigation. Structural studies are performed using X-ray diffraction (XRD). Microstructural properties are studied using scanning electron microscopy (SEM) and specific surface area studies are performed using Brunauer-Emmet-Teller (BET) method. XRD studies show that multiphase structures are obtained as a result of 1h sintering at 700?C1200 °C for both pure bone and TiO₂-bone composite materials. The factors affecting the transport of different heavy metal ions through the selected membranes are determined from permeation flux measurements. It is found that membrane pore size, membrane surface roughness and membrane surface charge are the key parameters that control the transport or rejection of heavy metal ions through the selected membranes.     

Preparation and Thermodynamic Properties of Camphene/Stearic Acid Composites as Phase-Change Materials in Buildings

In this study, a series of shape-stabilized phase-change materials (PCMs) of camphene/stearic acid (CS) were prepared and their thermal properties were measured by differential scanning calorimetry. The results indicated that the mixture consisting of 60 mass% camphene and 40 mass% stearic acid is the most favorable as a PCM, in terms of the phase-change temperature and latent heat. Thereafter, the CS was absorbed in fly ash, pyroclastic, barite, and marble powder, which acts as a supporting material, to prepare four kinds of composite-based PCMs. DSC, FT-IR, and scanning electron microscopy measurements were made to investigate the structures and properties of the PCMs. DSC results showed that the latent heats of melting and freezing of the composite PCMs were sharply decreased. Morphology and structural characterization revealed that, in form-stable PCMs, the dispersion of the supporting materials in the camphene/stearic acid matrix is homogeneous and there is no chemical interaction between the CS and composites. The composite PCMs showed excellent thermal stabilities and reliabilities, when their phase-change temperatures were concerned. These indicate that the prepared composite-based PCMs are suitable for thermal energy storage because of their applicable temperature range, thermal reliability, and chemical stability.     

Humidity sensing performance of in-situ fabricated Cu/Cu2O/Cu2S-polymer nanocomposite via polyphenylene sulphide cyclisation route

We herein report the feasibility of novel polymer-inorganic solid state reaction route for simultaneous in situ generation of Cu2S and Cu nanostructures in polymer network. Polyphenylene Sulphide (PPS) which is engineering thermoplastic acts as chalcogen source as well as stabilizing matrix for the resultant nano products. Typical solid state reaction was accomplished by simply heating the physical admixtures of the two reactants i.e., copper acetate and PPS by varying molar ratios mainly 1:1, 1:5, 1:10, 1:15, 1:20 at the crystalline melting temperature (285 degrees C) of PPS. The synthesized products were characterized using various physicochemical characterization techniques like X-ray Diffractometry, Field emission Scanning Electron Microscopy, Transmission Electron Microscopy, UV-Visible spectroscopy and X-ray photoelectron spectroscopy. The prima facie observations suggest occurrence of nanocrystalline Cu2S in case of product obtained with equimolar ratio, whereas remaining samples show mixture of Cu and Cu2O. The TEM analysis reveals nanoscale polydispersity (5-60 nm) and prevalence of mainly spherical morphological features in all the cases with occasional indications of plate like and cubical morphological features depending upon the molar ratio of the reactants. The humidity sensing characterization of these nanocomposites was also performed. The resistivity response with the level of humidity (20 to 70% RH) was compared for these nanocomposites. The linear response is obtained for all the samples. The sensitivity of 1:1 molar ratio sample was found to be maximum among all the samples.