Papers by Keyword: Bone

Abstract: Magnetic nanoparticles have been used extensively as drug delivery materials in recent years [1,2]. The present research goal is to treat bone diseases (such as osteoporosis and infection) by using surface modified magnetic nanoparticles. Magnetite (Fe3O4) and maghemite (Fe2O3) were synthesized and coated with calcium phosphate (CaP). The resulting nanoparticles were treated hydrothermally to change the crystalline properties of CaP. Nanoparticles were characterized via transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). TEM was also used to study the uptake of nanoparticles into osteoblasts (OB) and bacteria. OB proliferation experiments were conducted after 1, 3 and 5 days in the presence of the various iron oxide nanoparticles alone and CaP coated iron oxide magnetic nanoparticles. OB proliferation experiments were also conducted after 1, 3 and 5 days in the presence of various concentrations of CaP coated nanoparticles to examine a possible concentration dependent trend on OB density. Staph epidermidis were incubated with different doses of Fe3O4 to determine the effect of these nanoparticles on bacteria activity. Results of this in vitro study demonstrated greater OB functions and inhibited bacteria functions in the presence of select magnetic nanoparticles. In summary, the results of this study showed that magnetic nanoparticles should be further studied for various orthopedic applications.

Abstract: An excised and dried ulna was vibrated at its balance pnoint about 42% (0.1m) along the length from the olecranon process, using an electromagnetic vibrator. The vibration was carried out in the anterior-posterior plane. The bone response to the mechanical vibration was picked up at equal intervals (0.02m) along the length of the bone in the plane of the vibration, using an accelerometer attached to the bone. From the response curve of the bone, the resonant frequencies at the various pick- up positions were identified. Analysis of the data shows that when the responses were picked up using the accelerometer at 0.02m proximal, and 0.1m distal, to the point of vibration, the excised ulna vibrated in the fundamental mode like a fixed-fixed beam at resonant frequencies of 340 Hz and 355Hz respectively. For resonant frequencies greater than 650 Hz, the ulna vibrates like a fixed-free beam and at modes greater than the fundamental. It is suggested from this study that the vibration of the long bone in the fundamental mode lends itself to detailed analysis in the use of resonant frequency method in the assessment of the bone quality.

Abstract: We have used zinc aluminate nanostructured films deposited by spray pyrolysis to determine its biocompatibility assessed by cells attachment and cell differentiation. Cell attachment onto zinc aluminate showed an increase of 53, 81 and 86% at 180, 300 and 420 minutes (p<0.05) when compared to controls. Mineralization was analyzed at 5 and 14 days of culture by scanning electron microscopy, microanalysis and atomic force microscopy. Our results showed in experimental culture a higher density of mineral-like tissue with small needle-shaped crystal and granular nanoparticles with preferential orientation when compared to controls. The composition of the mineral-like tissue deposited in zinc aluminate nanostructured material had a Ca/P ratio of 1.6, whereas control culture had a Ca/P ratio of 1.50. Our finding revealed that ZnAl2O4 promoted higher expression of type I collagen, bone sialoprotein, osteocalcin and alkaline phosphatase, suggesting that zinc aluminate provides a microenvironment that favors mineral formation and cell differentiation. Our results point to the potential use of ZnAl2O4 for the osteoinductive process in biomedical implants.

Abstract: The surface of an endosseous implant has fundamental importance in forming mechanical and chemical connection with osseous tissue. One of the methods of enlarging area is using technology of powder metallurgy. The paper presents research regarding osteointegration of porous materials for implants made for Co-Cr-Mo and titanium with Bioglass type-S2. The research was made on the castrated goats averaging one year of age, from this oneself herds. Bone growth process on surfaces of implants made with additional bioglass was significantly intense. The amount of osseous tissue and the number of connection points are significantly increased. On surfaces of titanium implants few areas of stochastic callus formation were observed. In that case areas of preferential bone integration have uneven surface due to technological process. A significant difference appears in osseous tissue growth morphology on implant surface. In porous implants bone grows around the pores of an implant. The obtained results showed that porosity influences callus growth intensity beneficially on the implant structure. Use of bioglass increases bone growth intensity on implant surface.

Abstract: The synthetic nanostructured HA powder was prepared by the reaction of calcium hydroxide Ca(OH)2 aqueous solution and phosphoric acid H3PO4. The powders were foamed using hydrogen peroxide and heat treated at temperatures ranging from 120 to 700°C. Bovine deproteinized bone BioOss was used as a reference material. Elemental analysis, X-ray diffraction, chemical analysis, differential thermal analysis, scanning electron microscopy, gas adsorption and mercury porosimetry were used to characterize the precipitates. In vitro cytotoxicity test and the preclinical evaluation of this material were performed. In vivo tests were carried out in the tibiae of beagle dogs. All animals were euthanized 3 and 6 months after implantation. The material degradation and new bone formation was observed. The process of precipitation and coagulation can be applied to obtain pure synthetic HA powder. Foaming with H2O2 represents a method suitable to produce HA material with higher surface area and porosity. The physico-chemical properties of HA granules and in vivo tests determined that synthetic scaffold is comparable with bovine bone material. No significant differences between synthetic HA150 scaffolds and bovine bone BioOss were observed in vivo. The heat treatment of HA results in slower resorption and remodeling.

Abstract: Bone is a kind of biomaterial in nature. It behaves favorable strength, stiffness and fracture toughness which are closely related to its fine microstructures. Scanning electron microscope (SEM) observation on a shinbone shows that the bone is a kind of natural bioceramic composite consisting of hydroxyapatite layers and collagen matrix. The hydroxyapatite layers are arranged in a parallel distribution and consist of many hydroxyapatite sheets. The fracture toughness of the bone was analyzed based on the representative model of the microstructure in the bone and the idea of maximum pullout energy. The analytical result shows that the long and thin shape as well as the parallel distribution of the hydroxyapatite sheets increase the maximum pullout energy of the sheets and enhance the fracture toughness of the bone.

Abstract: In this study, the insulin adsorption ability by synthetic hydroxyapatite was investigated. Hydroxyapatite before thermal treatment and heated at 900°C and 1100°C were incubated in a solution containing 32 mg insulin/gHA. Adsorption and desorption experiments were carried out at 37°C under constant and slowly stirring. From FTIR results it was observed that insulin was tightly attached to HA surface after 96 hours adsorption experiment. Thermal pre-treatment on HA samples had no effect on insulin adsorption. However, protein desorption was more pronounced on samples not submitted to thermal treatment.

Abstract: Bioactive ceramics such as β-tricalcium phosphate (β-TCP) promote and enhance biological fixation. Ceramics with a porous interconnected structure are suited for facilitation of bony ingrowth. An interconnected pore system with pore diameters in excess of 100 µm is required for cell penetration, tissue ingrowth, vascularization and nutrient delivery to the centre of the regenerating tissue. Human osteoblasts were cultured on the surface of a ceramic. In an in-vivo study, β-TCP samples with a porous interconnected structure were implanted into the femur of sheep and then investigated 6 weeks after operation. Histological analysis was performed on the area surrounding the implant. An indentation test was performed to complete failure of the bone/ceramic compound. Linear load, peak load and stiffness were recorded. All cylinders were found to be biocompatible and osteoconductive. Bone was more abundant in the outer ring than in the rest of the cylinder. The ceramic/bone compound was of low mechanical grade.

Abstract: Totally biodegradable and osteoconductive composite material consisting of polyhydroxybutyrate (PHB) and β-tricalcium phosphate (β-TCP) was manufactured for bone tissue repair. The composite production process was optimized with the help of differential scanning calorimetry (DSC) analyses. Thermogravimetric analyses (TGA) indicated that intended compositions for TCP/PHB composite could be achieved through this manufacturing route. Scanning electron microscopic (SEM) examinations revealed that TCP/PHB composite containing up to 40 vol.% of β-TCP had satisfactory distribution of micron-sized TCP particles in the composite. The good-quality composite will be further investigated in in vitro and in vivo experiments.

Abstract: Nanostructured composites inspired by structural biomaterials such as bone and nacre form intriguing design templates for biomimetic materials. Here we use large scale molecular dynamics to study the shock response of nanocomposites with similar nanoscopic structural features as bone, to determine whether bioinspired nanostructures provide an improved shock mitigating performance. The utilization of these nanostructures is motivated by the toughness of bone under tensile load, which is far greater than its constituent phases and greater than most synthetic materials. To facilitate the computational experiments, we develop a modified version of an Embedded Atom Method (EAM) alloy multi-body interatomic potential to model the mechanical and physical properties of dissimilar phases of the biomimetic bone nanostructure. We find that the geometric arrangement and the specific length scales of design elements at nanoscale does not have a significant effect on shock dissipation, in contrast to the case of tensile loading where the nanostructural length scales strongly influence the mechanical properties. We find that interfacial sliding between the composite’s constituents is a major source of plasticity under shock loading. Based on this finding, we conclude that controlling the interfacial strength can be used to design a material with larger shock absorption. These observations provide valuable insight towards improving the design of nanostructures in shock-absorbing applications, and suggest that by tuning the interfacial properties in the nanocomposite may provide a path to design materials with enhanced shock absorbing capability.