In vitro bioactivity of titanium-doped bioglass

Previous studies have suggested that incorporating relatively small quantities of titanium dioxide into bioactive glasses may result in an increase in bioactivity and hydroxyapatite formation. The present work therefore investigated the in vitro bioactivity of a titanium doped bioglass and compared the results with 45S5 bioglass. Apatite formation was evaluated for bioglass and Ti-bioglass in the presence and absence of foetal calf serum. Scanning electron microscopy (SEM) images were used to evaluate the surface development and energy dispersive X-ray measurements provided information on the elemental ratios. X-ray diffraction spectra confirmed the presence of apatite formation. Cell viability was assessed for bone marrow stromal cells under direct and indirect contact conditions and cell adhesion was assessed using SEM.     

Synthesis and in vitro bioactivity of a borate-based bioglass

A bioactive borate glass was synthesized through normal melting-derived route in this letter. The degradation and bioactivity of the glass were studied by the immersion of glass microspheres in a dilute K₂HPO₄ solution. The cell growth inhibition rate of the borate glass was examined by MTT assay. The conversion product of the borate glass was identified by XRD, SEM. It was confirmed that the borate glass had a rapid degradation rate, comparing with the silicate-based bioglass, 45S5 glass. HA formed from the borate glass, that is an indication of bioactive potential in vivo. MTT assay results demonstrate that the inhibition effect of B ions released from the borate glass on cell proliferation can be alleviated by diluting extract solution to a certain concentration (v/v ratio: 1:4, [B] < 1.792 mM). It is believed that the borate glass could be a desirable biomaterial for preparing scaffold of tissue engineering.     

Fabrication and characterization of biomorphic 45S5 bioglass scaffold from sugarcane

A biomorphic 45S5 bioglass scaffold has been fabricated from natural plant sugarcane successfully by a novel biotemplating process. Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetry and differential scanning calorimetry (TG-DSC) technologies were employed to characterize the morphology, phase and chemical composition of the products. Experimental results show that the as-fabricated 45S5 bioglass scaffold retained the microstructure of sugarcane very well, and consisted of major crystal phase Na₂Ca₂Si₃O₉ of hexagonal system, secondary crystal phase orthorhombic NaCaPO₄ and amorphous glass. The biomorphic 45S5 bioglass scaffold may be a promising candidate scaffold for bone tissue engineering.     

Properties of scaffolds based on chitosan and collagen with bioglass 45S5

Scaffolds based on chitosan (CTS), collagen (Coll) and glycosaminoglycans (GAG) mixtures cross‐linked by tannic acid (TA) with bioglass 45S5 addition were obtained with the use of the freeze‐drying method. The prepared scaffolds were characterised for morphology, mechanical strength and degradation rate. Moreover, cell viability on the obtained scaffolds was measured with and without the presence of ascorbic acid and dexamethasone. The main purpose of the research was to compare the effectiveness of bioglass 45S5 influence on the physicochemical and biological properties of scaffolds. The results demonstrated that the scaffolds based on the blends of biopolymers cross‐linked by TA are stable in an aqueous environment. Scanning electron microscope images allowed the observation of a porous scaffold structure with interconnected pores. The addition of bioglass nanoparticles improved the mechanical properties and decreased the degradation rate of composite materials. The biological properties were improved for 20% tannic acid addition compared to 5%. However, the addition of bioglass 45S5 did not change to cells response significantly.Inspec keywords: biomedical materials, drying, porous materials, freezing, tissue engineering, proteins, nanofabrication, bone, scanning electron microscopy, polymers, molecular biophysics, cellular biophysics, nanoparticles, porosityOther keywords: chitosan, collagen, glycosaminoglycans, bioglass 45S5 addition, freeze‐drying method, degradation rate, ascorbic acid, dexamethasone, physicochemical properties, biological properties, porous scaffold structure, bioglass nanoparticles, mechanical properties, tannic acid addition, scanning electron microscopy     

Microstructure and in vitro behaviour of 45S5 bioglass coatings deposited by high velocity suspension flame spraying (HVSFS)

The high-velocity suspension flame spraying technique (HVSFS) was employed in order to deposit 45S5 bioactive glass coatings onto titanium substrates, using a suspension of micron-sized glass powders dispersed in a water + isopropanol mixture as feedstock. By modifying the process parameters, five coatings with different thickness and porosity were obtained. The coatings were entirely glassy but exhibited a through-thickness microstructural gradient, as the deposition mechanisms of the glass droplets changed at every torch cycle because of the increase in the system temperature during spraying. After soaking in simulated body fluid, all of the coatings were soon covered by a layer of hydroxyapatite; furthermore, the coatings exhibited no cytotoxicity and human osteosarcoma cells could adhere and proliferate well onto their surfaces. HVSFS-deposited 45S5 bioglass coatings are therefore highly bioactive and have potentials as replacement of conventional hydroxyapatite in order to favour osseointegration of dental and prosthetic implants.     

Indentation-induced residual stresses in 45S5 bioglass and the stress effect on the material dissolution

Using microindentation technique, localized residual stresses were created in 45S5 bioglass. The indentation-induced residual stresses increased with increasing the indentation load for the same distance to the indent center; and the magnitude of average local residual stress decreased with the increase in the distance to the indent center. The stresses-assisted dissolution of the 45S5 bioglass was demonstrated by studying the growth behavior of radial cracks in phosphate buffer solution. A linear relation between the indentation load and the ratio of the change in crack length to the square root of time was established, which was supported by experimental results.     

In vitro biocompatibility of fluorinated polyurethanes

The in vitro biocompatibility of fluorinated polyurethanes (FPUs), labelled as FPU 42, 52, 58, and 60, was evaluated by means of thrombogenicity, cytoxicity and cytocompatibility tests. Cardiothane^® was taken as control material. The thrombogenicity was tested on thin material films by measuring the activation of prekallikrein (PKK) to kallikrein (KK). Level I cytoxicity tests of the bulk materials, i.e. Neutral Red (NR) uptake, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), and Kenacid Blue (KB) assays, were performed to assess the influence of the polymer extracts on, respectively, lysosomes, mitochondria and cell proliferation. The cytocompatibility was evaluated, on thin membranes made by a spraying phase-inversion process, by measuring the area of the polymer surface covered by human umbilical vein endothelial cells (HUVEC) 1 week after seeding. The results indicate that all the polymers are not thrombogenic, and not cytotoxic. The FPUs that contain polycaprolactone glycol (PCLG) (FPU 52 and 60) instead of poly (tetramethylene ether) glycol (PTMEG) (FPU 42 and 58) as soft segment show the lowest thrombogenicity and the best cytocompatibility.     

Cerium-doped bioactive 45S5 glasses: spectroscopic,redox, bioactivity and biocatalytic properties

The ability of Ce-containing bioactive glasses, based on 45S5 Bioglass^®, to inhibit oxidative stress in terms of reduction in hydrogen peroxide and superoxide (O₂ ^?), by mimicking the catalase and superoxide dismutase activity is reported in this work. The characterization is performed on the powders of pristine glasses and after the soaking in H₂O₂ solutions and simulated body fluid. The glass samples are analysed by XPS, XRD, UV–Vis and FT-IR. The best catalyst activities are obtained for the glass with the highest content of cerium (H_5.3 = 5.3 mol% of CeO₂ in the nominal glass composition), and the best Ce³⁺/Ce⁴⁺ ratio in terms of catalase mimetic activity is found to be a function of H₂O₂ concentration. Moreover, the detailed study of the surface during the mimic enzymatic activity tests shows the formation of a Ca-P-rich layer on the glass surface, where the presence of Ce ions favours the formation of CePO₄. The phosphate in turn inhibits the formation of hydroxyapatite, decreasing the bioactivity of the glass with the highest of CeO₂ in the glass composition. This work shows the effect of Ce³⁺/Ce⁴⁺ ratio towards the catalase mimetic activity and for the first time the superoxide dismutase mimetic activity of Ce-containing 45S5-derived glasses.     

In vitro biocompatibility testing of polylactides

Four high-molecular weight polylactides, three poly-l-lactides of 100, 250 and 500 kDa and a poly-dl-lactide of 400 kDa, were tested qualitatively in vitro. Cells were cultured on polylactide films and with media based on the artificially aged polylactides, as well as with different concentrations of the final degradation products (monomers). Implant site-related cell types were selected. Three kinds of epithelial cells (middle ear, ear canal and nasal septum) as well as fibroblasts and osteosarcoma cells were used. Characteristic of all four polylactides was the normal morphology of cells when cultured on polylactide films and with the artificially ageing media. Although the polylactide films revealed still uncovered spots after 14 days culture, the control cultures were already confluent. The different concentrations of monomers revealed normal cell morphologies except for the 10 mg ml^-1 concentration, which showed larger fibroblasts, and the nasal septum epithelium showed more signs of terminal differentiation for the 10 mg ml^-1 d-monomer than was seen for the l-monomer even if the osmolarity was adjusted. The degradation products of polylactide are not expected to cause adverse reactions when implanted, since cell cultures with monomer concentrations up to 1 mg ml^-1 resulted in normal morphologies. In the present study the cells were not able to cover the polylactide films completely.     

In vitro biocompatibility of EPM and EPDM rubbers

The in vitro toxicity of two EPDM rubbers (K 778 and K 4802) and one EPM rubber (K 740) was tested using human fibroblasts. The modulus of elasticity of each rubber was varied by exposure to different amounts of electron-beam radiation (0, 5 and 10 Mrad). The short-term in vitro toxicity was tested by culturing cells on polymer films. The long-term effect of ageing was simulated by growing fibroblasts in nutrient media prepared from extracts of heat-exposed materials. Cell cultures were studied both quantitatively and (ultra) structurally. Growth curves obtained in the toxicity test did not differ significantly from control values at any day of observation, and also showed that electron-beam radiation did not alter the biocompatibility. The same results were found for all but one material in the artificial ageing test. The number of cells in the K4802/10 Mrad extraction medium was decreased. Ultrastructurally no gross deviations from normal morphology were observed, either in the direct contact test or in the artificial ageing test. The most characteristic feature was a somewhat dilated endoplasmic reticulum. In summary, the in vitro biocompatibility of EPDM-rubbers as observed in this study is satisfactory and motivates further investigation of their biocompatibility in animal experiments.     

Effects of biosilicate and bioglass 45S5 on tibial bone consolidation on rats: a biomechanical and a histological study

The purpose of this study was to investigate the effects of Bioglass 45S5^® and Biosilicate^®, on bone defects inflicted on the tibia of rats. Fifty male Wistar rats were used in this study, and divided into five groups, including a control group, to test Biosilicate^® and Bioglass^® materials of two different particle sizes (180–212 μm or 300–355 μm). All animals were sacrificed 15 days after surgery. No significant differences (P > 0.05) were found when values for Maximal load, Energy Absorption and Structural Stiffness were compared among the groups. Histopathological evaluation revealed osteogenic activity in the bone defect for the control group. Nevertheless, it seems that the amount of fully formed bone was higher in specimens treated with Biosilicate^® (granulometry 300–355 μm) when compared to the control group. The same picture occurred regarding Biosilicate^® with granulometry 180–212 μm. Morphometric findings for bone area results (%) showed no statistically significant differences (P > 0.05) among the groups. Taken together, such findings suggest that, Biosilicate^® exerts more osteogenic activity when compared to Bioglass^® under subjective histopathological analysis.     

Spark plasma sintering of sol-gel derived 45S5 Bioglass®-ceramics: Mechanical properties and biocompatibility evaluation

This work aims to find an efficient sintering technique and optimal sintering conditions of a novel sol-gel derived Bioglass®-ceramic powder so as to achieve much improved mechanical properties compared to conventional Bioglass®. To this end, the spark plasma sintering (SPS) technique was for the first time used to densify the sol-gel derived Bioglass®-ceramic powder. It was found that the sol-gel derived Bioglass®-ceramics sintered with the SPS technique at 950 °C for 15 min had a high Young's modulus value of ~ 110 GPa, which was comparable to that of compact bone and significantly higher than the maximal value achieved by the conventional heat treatment. Moreover, the Bioglass®-ceramic compacts sintered with SPS released alkaline ions slowly and as a result, these highly densified Bioglass®-ceramics exhibited better cytocompatibility at the early stage of cell culture testing, compared to the conventional Bioglass®. Hence, the SPS technique is recommended to be used in the process of sol-gel derived Bioglass®-ceramics and its tissue engineering scaffolds.     

In vitro bioactivity of novel tricalcium silicate ceramics

In this study, bone-like apatite-formation ability of tricalcium silicate (Ca₃SiO₅) ceramics in simulated body fluid (SBF) was evaluated and the in vitro degradability was investigated by soaking in Ringer’s solution. The effect of ionic products from Ca₃SiO₅ dissolution on osteobalsts proliferation was investigated. The result indicated that hydroxyapatite (HA) was formed on the surface of the Ca₃SiO₅ ceramics after soaking in SBF for 1 day, and Ca₃SiO₅ ceramics could degraded in Ringer’s solution. The Si ions from Ca₃SiO₅ dissolution at certain concentration range significantly stimulated osteoblasts proliferation. Our results show that Ca₃SiO₅ ceramics possess bone-like apatite-formation ability and degradability, and can release soluble ionic products to stimulate cell proliferation.     

钛氧膜生物相容性与生物活性的研究与应用

对钛氧膜的生物相容性和生物活性的研究及应用进行了评述.重点讨论了钛氧膜的制备方法、钛氧膜的活化处理方式以及钛氧膜在心血管材料和骨替代材料中的应用前景.     

溶胶-凝胶法制备镁蔷薇辉石的体外生物活性研究

用溶胶-凝胶法制备出纯相镁蔷薇辉石(Ca3MgSi2O8)粉体,并在10MPa的轴向压力下,将其压制成尺寸为Ф10mm×5mm的圆柱状块体,通过模拟体液浸泡对其体外生物活性进行研究.用X射线衍射(XRD)及扫描电镜(SEM)分别对粉体以及浸泡后形成的羟基磷灰石(Hap)的物相和表面形貌进行表征.结果表明:在约1400℃的煅烧温度下可以得到纯相镁蔷薇辉石粉体,其粒径约为1～3μm;圆柱状镁蔷薇辉石在模拟体液浸泡7d后就能明显检测到表面有羟基磷灰石生成,浸泡14d后呈结晶较好的蠕虫状结构.因此,溶胶-凝胶法合成的镁蔷薇辉石具有良好的诱导羟基磷灰石形成能力和体外生物活性.     

In vitro biodegradation and biocompatibility of gelatin/montmorillonite-chitosan intercalated nanocomposite

The intercalated nanocomposite of gelatin/montmorillonite-chitosan (Gel/MMT-CS) was prepared via the solution intercalation process. In vitro degradation tests showed that the nanocomposite had a lower degradation rate than Gel-CS composite. And the introduced intercalation structure endowed Gel/MMT-CS nanocomposite with a controllable degradation rate when changing the MMT content. Cells attachment, spread and proliferation on the Gel/MMT-CS membranes were investigated by scanning electron microscopy (SEM) and mitochondrial activity assay. The results provided evidences of good adhesion, proliferation and morphology of rat stromal stem cells on Gel/MMT-CS membranes compared to the tissue culture plates (TCPs), making the Gel/MMT-CS nanocomposite a promising candidate towards tissue engineering.     

Primary bone-derived cell colonization of unconditioned and pre-conditioned Bioglass 45S5 surfaces in vitro

Samples of Bioglass 45S5, a bioactive glass that reacts chemically on immersion in an aqueous environment and following implantation can bond with bone, were immersed in culture medium with foetal calf serum as a source of proteins for periods of 1–11 days. Energy dispersive spectroscopy (EDS) revealed that over 11 days immersion, the Bioglass surface was rich in Si relative to Ca and P and scanning electron microscopy (SEM) showed that the Bioglass developed surface reaction layers. Samples conditioned in culture medium and previously untreated samples were used as substrates for primary osteoblast or periosteal cell cultures, to allow comparison of the effects of different Bioglass surface development, on subsequent cell attachment. SEM examination revealed that pre-conditioned Bioglass was a more suitable substrate for osteoblast colonization than previously undeveloped Bioglass, whereas periosteal cells colonized all samples equally well and more rapidly than osteoblasts.     

In vitro and in vivo studies on biocompatibility of carbon fibres

In the present study we focused on the in vitro and in vivo evaluation of two types of carbon fibres (CFs): hydroxyapatite modified carbon fibres and porous carbon fibres. Porous CFs used as scaffold for tissues regeneration could simultaneously serve as a support for drug delivery or biologically active agents which would stimulate the tissue growth; while addition of nanohydroxyapatite to CFs precursor can modify their biological properties (such as bioactivity) without subsequent surface modifications, making the process cost and time effective. Presented results indicated that fibre modification with HAp promoted formation of apatite on the fibre surface during incubation in simulated body fluid. The materials biocompatibility was determined by culturing human osteoblast-like cells of the line MG 63 in contact with both types of CFs. Both tested materials gave good support to adhesion and growth of bone-derived cells. Materials were implanted into the skeletal rat muscle and a comparative analysis of tissue reaction to the presence of the two types of CFs was done. Activities of marker metabolic enzymes: cytochrome c oxidase (CCO) and acid phosphatase were examined to estimate the effect of implants on the metabolic state of surrounding tissues. Presented results evidence the biocompatibility of porous CFs and activity that stimulates the growth of connective tissues. In case of CFs modified with hydroxyapatite the time of inflammatory reaction was shorter than in case of traditional CFs.     

In vitro evaluation of biocompatibility of different wound dressing materials

The in vitro biocompatibility of newly developed wound dressings consisting of different chitosan salts (chitosan lactate, glutamate and chloride) and a chitosan derivative (methylpyroolidinone chitosan) was compared with three commercially available wound dressings made of collagen, calciumalginate, and gelatin, by evaluation in a fibroblast cell culture system. Three experimental models which reflect relevant stages of wound healing were used, and the significant influence of the experimental setting on the results was demonstrated. Collagen and methylpyrrolidinone chitosan were the most compatible materials under the investigated test conditions. Chitosan chloride and glutamate were the least compatible substances. The results indicated that wound dressings made of chitosan lactate and methylpyrrolidinone chitosan as well as the three commercially available dressings are well tolerated.