Papers by Keyword: Biomaterial

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Authors: M.T. Oliveira, S. Lucena, J. Potes, M.C. Queiroga, S. Rehman, K. Dalgarno, A. Ramos, J.C. Reis
Abstract: The testing of novel biomaterials for percutaneous vertebroplasty depends on suitable animal models. The aim of this study was to develop ex vivo a reproducible and feasible model of percutaneous vertebroplasty, for ulterior application in vivo. A large animal model was used (Merino sheep), due to its translational properties. Vertebroplasty was performed under tactile and fluoroscopic control, through a bilateral modified parapedicular access in lumbar vertebrae (n=12). Care was taken in order to avoid disruption of the vertebral foramen. The average defect volume was 1234±240 mm3. This mean volume ensures practical defects to test novel injectable biomaterials. 6 vertebrae were injected with a commercial cement (Cerament®, Bone Support, Sweden). Adequate defect filling was observed in all vertebrae. All vertebrae were assessed by microCT, prior to and post defect creation and after biomaterial injection. All vertebrae were mechanical tested. No mechanical failure was observed under loads higher than the physiological. Ultimately, this model is considered suitable for pre-clinical in vivo studies, mimicking clinical application.
Authors: Marina Salvarani Tonoli, Marisa Masumi Beppu
Abstract: The aim of this work was to study the phase transformation during the setting reaction of beta tricalcium phosphate (β-TCP) and phosphoric acid with chitosan solution added. To follow the kinetics of the phase transformation, two methods were used: x-ray diffraction (XRD) was used to study the phase evolution during the hardening process in real time, and was also used in samples where the reaction was supposedly stopped in different times using acetone, as indicated in literature. The setting reaction occurs so fast that the phase transformation could not be observed, but it was possible to invalidate the second mentioned method for this system, as it induces the final product dicalcium phosphate dihydrate DCPD (brushite) to be converted into his anhydrous form dicalcium phosphate DCP (monetite). The addition of chitosan in order to improve biocompatibility was successfully done, it could be observed that chitosan inhibits brushite crystallization in the first moment of the reaction, but the final product was not affected by it.
Authors: Anke Bernstein, Renate Gildenhaar, Georg Berger, Hermann O. Mayr
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.
Authors: Sittiporn Punyanitya, Rungsarit Koonawoot, Anucha Ruksanti, Sakdiphon Thiansem, Anirut Raksujarit, Watchara Sontichai
Abstract: Biodegradable scaffold is an accepted and commercialized medical alternative choice for bone regeneration. In this project, we used our new invention, porous starch-Hydroxyapatite (HA) composite for in vivo clinical trial. The products were prepared from medical grade Thai rice starch mixed with high purity (>97%) HA powder from fresh cow bone, and already passed in vivo animal biocompatibility test, then processed by freeze-drying. There were 44 volunteers from orthopedic and neurosurgical division, 4 and 40 patients, respectively. The results were assessed by operative surgeons and nurses, pre-and intraoperative period, including size appropriateness, comfort handle, ease of cutting, void space filling, water stability, product weight, shelf storage, package opening, contamination risk and waste removal. All average satisfactory scales were more than 95% rating. For postoperative period, at least 6 months, the soft tissue swellings around surgical areas were resoluted about 3 days as usual healing process. There were no any symptoms or signs of infection or allergic reactions. The follow up of x-ray imaging showed well ossification about 2 months. All patients have gained good functional performance. So porous starch-HA composites biomaterial can be used for human bone and skull regeneration with completely safety and efficacy.
Authors: Rossella Bedini, Deborah Meleo, Raffaella Pecci
Abstract: After a short introduction to bone substitute biomaterials and X-ray microtomography, this article describes a research work carried out for in-vitro characterization of bone substitute biomaterials as well as for in-vivo investigation of human bone grafted with biomaterials. Three different bone substitute biomaterials have been analyzed in-vitro by means of 3D microtomographic technique, while human bone samples grafted with bone substitute biomaterials are investigated by 3D microtomography and histological techniques. 3D images of bone substitutes and human bone samples with biomaterials have been obtained, together with morphometric parameters, by microtomography . 2D histological images have also been obtained by traditional technique only for human bone samples with biomaterials. Compared to traditional histological analysis, 3D microtomography shows better results for investigating bone tissue and bone substitute biomaterial, and in a short time. Nevertheless, histological analysis remains the best technique for the observation of soft tissue and blood vessels.
Authors: M. Dourandish, Dirk Godlinski, Abdolreza Simchi
Abstract: The fabrication of complex-shaped parts out of Co-Cr-Mo alloy and 316L stainless steel by three-dimensional printing (3DP) is studied using two grades of each alloy with average particle size of 20 and 75 )m, respectively. To produce sound specimens, the proper 3DP processing parameters were determined. The sintering behavior of the powders is characterized by dilatometric analysis and by batch sintering in argon atmosphere at 1280°C for 2h. The 3DP process has successfully produced complex-shaped biomedical parts with total porosity of 12-25% and homogenous pore structure, which is suitable for tissue growth into the pores.
Authors: Petri Sane, Simo Kilpeläinen, F. Tuomisto
Abstract: In this work a novel detector setup for PALS-studies on biomolecular materials is presented. When pursuing optimal detecting efficiency and lifetime component resolution one must make compromises when using only one detector pair. With smaller scintillation heads the resolution is higher, but the detecting efficiency decreases and vice versa. When measuring biological materials that do not withstand long measurement periods, sacrifices are made for gaining efficiency. The price of this optimization is low resolution of the lifetime components, namely separating the always present water’s lifetime component of ~1.8 ns from the actual material’s lifetime component, typically >2 ns. A solution to this problem is measuring the annihilation spectra with two individual detector pairs simultaneously. Using analog setup, it would require duplicate ADC-hardware that are both expensive and degrade by time. With a fully digital setup, the need for hardware is smaller and the precision of the setup is constant during its service life.
Authors: Kanthi Lewis, U. Boonyang, L. Evans, S. Siripaisarnpipat, Besim Ben-Nissan
Abstract: This study aims to characterize the structure and properties of crocodile bone to assess the potential for use in biomedical applications. Crocodile bone samples obtained from Thailand (Crocodylus siamensis) and Australia (Crocodylus porosus), being the tail and the tibia respectively, were treated to remove organic material and the inner spongy (trabecular) material. The dense cortical bone was used for comparative instrumental analyses. Specific comparisons were made against bovine cortical bone and pure synthetic hydroxyapatite. The material was then analyzed using simultaneous differential thermal analysis/thermogravimetric analysis (DTA/TGA), Fourier- Transform infrared spectroscopy (FTIR), and X-ray diffraction analysis (XRD). Imaging of full bone samples was also conducted using an environmental scanning electron microscopy (ESEM). The SEM provided valuable information through the imaging of samples, showing a markedincrease in bone porosity for crocodile material when compared to bovine samples. The crystallinity and/or crystallite size of carbonated hydroxyapatite has been found to be lower than synthetic apatite, with the tibia being the least crystalline of the bone types studied. The crystallinity index (CI) is used as a measure of crystallite size and internal strain. The strain is affected by substitutions in the structure and these results provide a starting point for comparison of the resulting mechanical properties. There is a need for any biomaterial chosen for bone replacement to allow adequate osteointegration. Thus the study this far shows that crocodile bone is a very promising source of carbonated apatite for biomedical applications.
Authors: Gang Sun, Yan Fang
Abstract: The microstructure, hydrophobicity and chemical composition of the locust and moth wing surfaces were investigated by a scanning electron microscope (SEM), a contact angle meter and a Fourier transform infrared spectrometer (FT-IR). The hydrophobicity models were established on the basis of the Cassie-Baxter equation. The locust and moth wing surfaces are composed of naturally hydrophobic materials, but exhibit different complex wettability. The locust wing surface is of extremely high adhesion (sliding angle>180°) and superhydrophobicity (contact angle 151.5~157.3°), while the moth wing surface is of low adhesion (sliding angle 1~3°) and superhydrophobicity (contact angle 150.5~155.6°). The complex wettability of the wing surfaces ascribes to the cooperative effect of material element and structural element. The locust and moth wings can be potentially used as biomimetic templates for design and preparation of novel functional interface and no-loss microfluidic transport channels.
Authors: Yuan Zhou
Abstract: This paper was concerned with the effects of ultrasonication on the gelation behavior of silk fibroins (SF), and a comparison of Domestic and Wild silkworms was studied. The results show that: with the increase of ultrasonic power, the gelation time of domestic (Bombyx Mori) SF solution decreased sharply. But wild silkworms (Antheraea yamamai and Antheraea pernyi) SF were different, When the power of utrasonication was lower than 400-500 W, the velocity of gelation were accelerated, and when the ultrasonic power was higher than 400-500W, the gelation time were delayed. Whatever domestic or wild silkworms, the mechanism of the effects of ultrasonication on the gelation behavior was that the ultrasonication promoted the structural transformation of SF molecules from random coil or α-helix to β-sheet.
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