Bio-Medical Materials and Engineering - Volume 25, issue 2
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Bio-Medical Materials and Engineering is to promote the welfare of humans and to help them keep healthy. This international journal is an interdisciplinary journal that publishes original research papers, review articles and brief notes on materials and engineering for biological and medical systems.
Articles in this peer-reviewed journal cover a wide range of topics, including, but not limited to: Engineering as applied to improving diagnosis, therapy, and prevention of disease and injury, and better substitutes for damaged or disabled human organs; Studies of biomaterial interactions with the human body, bio-compatibility, interfacial and interaction problems; Biomechanical behavior under biological and/or medical conditions; Mechanical and biological properties of membrane biomaterials; Cellular and tissue engineering, physiological, biophysical, biochemical bioengineering aspects; Implant failure fields and degradation of implants. Biomimetics engineering and materials including system analysis as supporter for aged people and as rehabilitation; Bioengineering and materials technology as applied to the decontamination against environmental problems; Biosensors, bioreactors, bioprocess instrumentation and control system; Application to food engineering; Standardization problems on biomaterials and related products; Assessment of reliability and safety of biomedical materials and man-machine systems; and Product liability of biomaterials and related products.
Abstract: The aim of the present study was to determine the degradability of aliphatic polyurethanes, based on a different amount of synthetic, atactic poly[(R,S)-3-hydroxybutyrate] (a-PHB), in hydrolytic (phosphate buffer) and oxidative (H2 O2 /CoCl2 ) solutions. The soft segments were built with atactic poly[(R,S)-3-hydroxybutyrate] and polycaprolactone or polyoxytetramethylenediols, whereas hard segments were the reaction product of 4,4′-methylenedicyclohexyl diisocyanate and 1,4-butanediol. The selected properties – density and morphology of polymer surfaces – which could influence the sensitivity of polymers to degradation processes – were analyzed. The analysis of molecular mass (GPC), thermal properties (DSC) and the sample weight changes were…undertaken to estimate the degree of degradability of polymer samples after incubation in environments studied. Investigated polyurethanes were amorphous with the very low amount of crystalline phases of hard segments. The polyurethane synthesized with a poly[(R,S)-3-hydroxybutyrate] and polyoxytetramethylenediol at a molar ratio of NCO:OH=3.7:1 (prepolymer step) appeared as the most sensitive for both degradative solutions. Its weight and molecular mass losses were the highest in comparison to other investigated polyurethanes. It could be expected that playing with the amount of poly[(R,S)-3-hydroxybutyrate] in polyurethane synthesis the rate of polyurethane degradation after immersion in living body would be modeled.
Abstract: The aim of this study is to evaluate the feasibility of fabricating titanium(Ti)/hydroxyapatite(HA) composite and functionally graded implant by three-dimensional printing (3DP) technology. Nano-scale Ti and HA powders were mixed at the ratio of 8:2 and prepared with water-soluble binder. The Ti/HA composite CAD model was designed to be in cylinder shape (25 mm in diameter, 20 mm in height) with the 100% bond area in each layer. The functionally graded implant was 25 mm in diameter and 10 mm in height with two segments. The upper segment was composed of 100% Ti in each layer, whereas the lower was…composed of 80%Ti/20%HA. The composite and functionally graded implant were fabricated by 3DP and sintered at 1200°C under protective argon atmosphere. There occurred a chemical reaction between Ti and HA, in which new resultants of Ca3 (PO4 )2 , CaTiO3 , TiO2 and CaO were created. The sintered Ti/HA composite had the aperture size from 50 to 150 μm and the compressive strength of 184.3±27.1 MPa. The result of this study demonstrated that it was feasible to fabricate Ti/HA composite and functionally graded implant by 3DP technology. The microstructure and mechanical properties of Ti/HA composite and functionally graded implant were conductive to bone cell ingrowth, resulting in the wide application of this biocomposite.
Abstract: Four samples of four medical grade silicones were swollen in six “good” liquids (i.e. those with a good swelling ability, in which silicones swell appreciably) at 25°C, until they reached constant mass (i.e. equilibrium). The volume fraction, ϕ, of the silicone in the swollen sample was calculated for each grade of silicone. Using a combination of the six ϕ values obtained in this study and four of those obtained in a previous study, for each silicone grade, ϕ was plotted against δl , the liquid solubility parameter for the ten liquids used. Using a curve fitting technique a second-order polynomial…was plotted through the data points; the minimum in this polynomial provided a value for δp (the polymer solubility parameter). Furthermore, the results showed that the δp values obtained in this study (using ten liquids) were slightly but significantly greater (p<0.05) than those obtained in a previous study (using four liquids), for grade C6-165 only. Similarly, the χ and υ values obtained in the two studies were only significantly different (p<0.05) from each other, for grade C6-165.
Abstract: OBJECTIVE: The aim of the present study is to evaluate the efficacy of slow zinc (Zn) release from β-tricalcium phosphate powder (ZnTCP) containing 10 mol% Zn on rats with thermal burns. METHODS: The first-aid tapes were contained zinc sulfate (ZnSO4 ) solution, ZnTCP suspensions or zinc oxide ointment. After thermal burn treatments were performed on Zn-deficient rats, the groups D1, D2 and D3 were treated with tapes containing ZnTCP, ZnSO4 and zinc oxide ointment. The effects of the tapes on wound area, plasma Zn levels and alkaline phosphatase activity (Alp) were investigated. RESULTS: The wound area profiles…of all rat groups could be separated into before and after the scab formation at around day 6. The area under the curve (Aw-AUC) for wound area profiles, therefore, was evaluated as an index of therapeutic scores for the thermal wound. The order of Aw-AUC was D3>C>D2>D1. The degree of expansion at the initial stage by thermal burns of group D1 was the lowest and that of group D2 was the highest, and the order was D1<D3<C<D2. CONCLUSIONS: ZnTCP treatment could control the initial inflammation caused by thermal burns.
Keywords: Transdermal therapeutic system, tricalcium phosphate containing zinc, thermal burns, in vivo zinc release, wounded area, healing process
Abstract: BACKGROUND: The bilayer gelatin sealing sheet was developed as a safe, effective, easy-to-handle and low-cost hemostatic agent. OBJECTIVE: To examine the feasibility of gelatin sealing sheets using a canine arterial hemorrhage model. METHODS: In vivo degradation of gelatin sealing sheets was examined by implanting subcutaneously in rats. For the hemostatic and anti-adhesion efficacy investigations, femoral arteries of dogs were pricked with syringe needle to make a small hole and a gelatin (i.e. experimental group) or fibrin glue sealing sheet (i.e. control group) was applied on the hole to stop bleeding (n=8). After discontinuation of the bleeding, the skin…incisions were closed and re-examined 4 weeks postoperatively. RESULTS: From the degradation study, 4 h thermally treated gelatin sheet which degraded within 3 weeks in vivo was chosen for the further hemostatic study. In all cases of gelatin and fibrin glue sealing sheets, bleeding from the needle hole on canine femoral arteries was effectively stopped. Postoperative adhesions and inflammation at the site in the experimental group were significantly less than those in the control group (P<0.01 for adhesion scores). CONCLUSIONS: The gelatin sealing sheet was found to be as effective as the fibrin glue sealing sheet as a surgical hemostatic agent, and more effective in preventing postoperative adhesions.
Abstract: BACKGROUND: Poly-ether-ether-ketone (PEEK) has biomechanical and chemical properties that are excellent for biomedical applications; however, PEEK adhesion to bone or chondral tissue proceeds slowly due to poor hydrophilicity and other surface characteristics. OBJECTIVE: We investigated the structural change, hydrophilicity, and cytocompatibility of a PEEK surface after 172-nm xenon excimer UV-irradiation. METHODS: The surface characteristics before and after irradiation were evaluated by contact angle and ATR-FTIR measurements. Mouse osteoblast-like cells (MC3T3-E1) were cultured on PEEK plates and collected after 6, 12 and 24 h for cell adhesion analysis by crystal violet staining (CVS) and scanning electron microscopy (SEM).…RESULTS: UV-irradiation improved PEEK surface hydrophilicity, as indicated by a significant drop in water contact angle (p<0.05). Irradiated PEEK showed additional peaks around 3370 cm−1 and 1720 cm−1 , highlighting the generation of hydroxyl and carbonyl groups. CVS and SEM revealed improved adhesion to the PEEK surface after UV-irradiation. CONCLUSION: Our results suggest that 172-nm UV-irradiated PEEK may be used in biomedical applications that require good cell adhesion.
Abstract: BACKGROUND: There is considerable interest to develop accurate subject-specific biomechanical models of the knee. Most of the existing models currently do not include a representation of the posterior knee capsule. In order to incorporate the posterior capsule in knee models, data is needed on its mechanical properties. OBJECTIVE: To quantify the mechanical properties of the human posterior knee capsule through semi-static tensile tests. METHODS: Fifteen posterior knee capsule specimens (5 knees, 3 male, 2 female; age 79.2±7.9 years) were used to perform tensile tests. A medial, central and lateral specimen was taken from each knee. The cross-sectional area…was measured, after which semi-static tensile tests were performed to quantify the material properties. RESULTS: The stiffness of the capsule was randomly distributed over the regions. The global Young's modulus and yield strength was 8.58±10.77 MPa and 1.75±1.89 MPa, respectively. A strong correlation (ρ=0.900) was found between Young's modulus and yield strength. The location of failure was not associated with smallest cross-sectional area or highest strain. CONCLUSIONS: The results suggest that the posterior knee capsule does not have a systematic (medial–central–lateral) distribution of material properties. The posterior capsule may play an important role in knee joint mechanics, particularly when in hyper extension.
Keywords: Cross sectional area, material properties, posterior knee capsule, three-dimensional knee model, tensile test
Abstract: The physical properties of the stent surface influence the effectiveness of vascular disease treatment after stent deployment. During the expanding process, the stent acquires high-level deformation that could alter either its microstructure or the magnitude of surface roughness. This paper constructed a finite element simulation to observe the changes in surface roughness during the stenting process. Structural transient dynamic analysis was performed using ANSYS, to identify the deformation after the stent is placed in a blood vessel. Two types of bare metal stents are studied: a Palmaz type and a Sinusoidal type. The relationship between plaque length and the changes…in surface roughness was investigated by utilizing three different length of plaque; plaque length longer than the stent, shorter than the stent and the same length as the stent. In order to reduce computational time, 3D cyclical and translational symmetry was implemented into the FE model. The material models used was defined as a multilinear isotropic for stent and hyperelastic for the balloon, plaque and vessel wall. The correlation between the plastic deformation and the changes in surface roughness was obtained by intermittent pure tensile test using specimen whose chemical composition was similar to that of actual stent material. As the plastic strain is achieved from FE simulation, the surface roughness can be assessed thoroughly. The study found that the plaque size relative to stent length significantly influenced the critical changes in surface roughness. It was found that the length of stent which is equal to the plaque length was preferable due to the fact that it generated only moderate change in surface roughness. This effect was less influential to the Sinusoidal stent.
Abstract: OBJECTIVE: Mesenchymal stem cells (MSC) are transplanted for periodontal tissue regeneration, and the periodontal ligament (PDL) is regenerated using a cultured cell sheet. This cultured cell sheet is prepared using PDL-derived cells, growth factors, and amniotic membrane (AM). Dental pulp (DP)-derived cells can be easily obtained from extracted wisdom teeth, proliferate rapidly, and are less susceptible to bacterial infection than PDL-derived cells. Thus, to prepare a novel cell sheet, DP-derived cells were cultured on AM as a culture substrate for immunohistochemical examination. METHODS: Wisdom teeth extracted from three adults were cut along the cement-enamel border. DP tissue was collected,…minced, and primarily cultured. After three or four passage cultures, DP-derived cells were cultured on AM, followed by hematoxylin–eosin (H–E) and immunofluorescence staining. RESULTS: DP-derived cells cultured on AM formed a layered structure. Cells positive for vimentin, Ki-67, ZO-1, desmoplakin, CD29, 44, 105 or 146, STRO-1, collagen IV or VII or laminin 5 or α5 chain were localized. CONCLUSIONS: DP-derived cells proliferated on AM, while retaining the properties of DP, which allowed the cultured cell sheet to be prepared. In addition, the cultured cell sheet contained MSC, which suggests its potential application in periodontal tissue regeneration.
Abstract: A number of factors may have effects on hip fracture, for example, bone mineral density (BMD), body weight and height, femur length, femoral neck length, etc. It is not clear which factor(s) has the dominant effect on hip fracture. Therefore, the factors were investigated by a previously developed DXA (dual energy X-ray absorptiometry) based finite element model. The finite element model is patient-specific, as all information required in constructing the model was extracted from the patient's hip DXA image. DXA images of 180 patients were obtained from the Manitoba Bone Mineral Density Database. For each patient, a finite element model…was constructed and fracture risk indices (FRI) were calculated at the three critical locations on the hip, i.e. the femoral neck, the intertrochanter and the subtrochanter. Possible correlations between the fracture risk indices and the factors were then investigated. The obtained results indicated that, for hip fractures resulted from lateral fall, areal BMD and patient's body weight are two dominant factors, but effects from the other factors are not trivial. The study suggested that hip fracture is the result of combined effects from all the factors. Therefore, use of areal BMD alone in clinical assessment of fracture risk is not reliable.
Keywords: Hip fracture risk, dual energy X-ray absorptiometry (DXA), bone mineral density (BMD), finite element model, fracture factors