Bio-Medical Materials and Engineering - Volume 16, issue 2

Authors: Sakamoto, Yuki | Asaoka, Kenzo | Kon, Masayuki | Matsubara, Toshio | Yoshida, Kenichi

Article Type: Research Article

Abstract: The biological properties of a titanium (Ti) implant depend on its surface oxide film. The aims of the present study were to increase the specific surface oxide area on Ti using a porous structure and to study the relationship between the amount of apatite coating in simulated body fluid (SBF) and the actual surface area on titanium powders. Ti powders of 110 μm average diameter were sintered by spark plasma sintering. The sintered compacts had a porosity of 28%, a compressive elastic modulus of 7.9 GPa and an ultimate strength of 112 MPa. The compressive strength of the compacts was …increased to 588 MPa by subsequent annealing in a vacuum furnace at 1000°C for 24 h. The sintered compacts were treated with aqueous NaOH solution and subsequently heated at 600°C. The pretreated compacts showed apatite crystal precipitation in SBF. The amounts of precipitates through the compacts were compared with those of the Ti plate substrates subjected to the same chemical pretreatment. It was confirmed that the amounts of precipitates through the compacts were more than one hundred times higher than those on the Ti plates. It was concluded that the metal porous compacts developed may be used as functional materials for immobilizing functional proteins and/or drugs, because the precipitated apatite can adsorbed these substances. Show more

Keywords: Titanium, porosity, mechanical properties, metal surface treatment, SBF (simulated body fluids)

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 2, pp. 83-91, 2006

Authors: Mc Nally, L. | O'Sullivan, D.J. | Jagger, D.C.

Article Type: Research Article

Abstract: Silica is a commonly used filler in dental materials and as a reinforcing agent in industry. The aim of this study was to further investigate the effect of the addition of untreated and a novel surface treated silica on the transverse bend and impact strength of acrylic resin denture base material. It was hypothesized that the silica/resin composite materials would have an improved flexural and impact strength than the conventional heat-cured acrylic resin. Three types of untreated and two of treated silica powder were used in this study. The range of percentages used were 1%, 0.5%, 0.2%, 0.1%. The treated …particles were coated with hexamethyldisilazane or dimethyldichloridesilazane. Conventional heat cured acrylic resin was used as a control. The modulus of rupture for all groups of acrylic resin containing silica was significantly lower than for the control. The modulus of elasticity was not significantly greater than the control group. For the impact strength statistical analysis revealed a significant difference between the groups. There was a nonsignificant increase in the impact strength for specimens compared to the control. In conclusion the addition of silica to poly(methyl methacrylate) denture base materials did not produce a significant improvement in the transverse bend or impact strength compared to conventional heat-cured acrylic resin. The incorporation of untreated and surface treated silica cannot be recommended as a method of reinforcement. Show more

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 2, pp. 93-100, 2006

Authors: Yahia, L'H. | Manceur, A. | Chaffraix, P.

Article Type: Research Article

Abstract: Shape memory alloys (SMA) represent a large family of alloys that show unique characteristics. They have been exploited in several fields for diverse applications. For the last 20 years, these alloys and more particularly Ni–Ti alloys have revolutionized the field of metallic biomaterials. Applications in the biomedical area are multiple and these materials improve significantly the quality of the diagnostics, treatments and surgeries. To our knowledge, most devices are made of SMAs in the polycrystalline form. Nevertheless, the single crystal form shows several promising advantages especially concerning its mechanical performances. In this paper we describe the advantages, advances and limits …of using different SMA single crystals for biomedical applications, including biocompatibility and corrosion resistance. We also discuss the low response time of classical thermal SMAs as well as the new advances in research on magnetic SMA single crystals. Show more

Keywords: Shape memory alloys, magnetic shape memory, single crystal, bioperformance, biocompatibility, corrosion, fatigue, nickel–titanium, copper-based alloys

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 2, pp. 101-118, 2006

Authors: Chen, Yi-Chen | Hu, Kuang-Hu | Li, Fang-Zhen | Li, Shu-Yu | Su, Wan-Fang | Huang, Zhi-Ying | Hu, Ying-Xiong

Article Type: Research Article

Abstract: Recognition of lung cancer cells is very important to the clinical diagnosis of lung cancer. In this paper we present a novel method to extract the structure characteristics of lung cancer cells and automatically recognize their types. Firstly soft mathematical morphology methods are used to enhance the grayscale image, to improve the definition of images, and to eliminate most of disturbance, noise and information of subordinate images, so the contour of target lung cancer cell and biological shape characteristic parameters can be extracted accurately. Then the minimum distance classifier is introduced to realize the automatic recognition of different types of …lung cancer cells. A software system named “CANCER.LUNG” is established to demonstrate the efficiency of this method. The clinical experiments show that this method can accurately and objectively recognize the type of lung cancer cells, which can significantly improve the pathology research on the pathological changes of lung cancer and clinical assistant diagnoses. Show more

Keywords: Lung cancer cells, mathematical morphology, classification and recognition, clinical assistant diagnoses

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 2, pp. 119-128, 2006

Authors: Otsuka, Makoto | Tomita, Hisako | Otsuka, Kuniko | Kamae, Isao | Jorgenson, James A.

Article Type: Research Article

Abstract: Ibuprofen tablets on the market in Japan and the USA were compared by manual- and automatic-dissolution tests according to USP24 criteria. Dissolution test were performed in 900 ml of phosphate buffer of pH 7.2 at 37.0±0.5°C at 50 rpm for 60 min, and the time required for 70% dissolution (T70%) and 5% dissolution after 60 min (A60) were evaluated. The dissolution profiles of both Japanese and American tablets by the automatic-method showed almost the same profiles as those of the manual method. T70% of the American and Japanese tablets by the manual method were not significantly different (p>0.05) from the …automatic-method at various sampling positions. The A60 of the American and Japanese tablets by the manual-method was not significantly different (p>0.05) except at one position. The results indicate that the automatic-method was more reproducible than the manual-method, and also that systematic error was negligible. The T70% and A60 of the American tablets were significantly different (p<0.05) from the Japanese tablets. The American tablets were a film-coated over-the-counter drug and the Japanese tablets were a sugar-coated prescription drug. There was a difference in dissolution behavior between the dosage forms of the two countries. Show more

Keywords: Ibuprofen tablets, automatic-dissolution test, generic drug, international harmonization

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 2, pp. 129-135, 2006

Authors: Wiersma, Susanne | Dolan, Finbar | Taylor, David

Article Type: Research Article

Abstract: Some biomedical components involve the use of materials in microscopic quantities, i.e. in section sizes which are of the same order of magnitude as microstructural features in the material, such as grains. The mechanical behaviour of the material may be different when used in these quantities, compared to its behaviour in macroscopic amounts. An example of a microscopic component is the cardiovascular stent. To ensure the integrity of the stent during deployment and subsequent use, the designer must be able to simulate possible failure modes, i.e. monotonic fracture and fatigue, and the effect of stress concentrations. We carried out tests …on specimens of 316L stainless steel, with and without stress concentrations. We found a significant size effect, in which the behaviour of these microscopic specimens was different from that of larger, macroscopic specimens. Microscopic specimens had lower tensile strengths and higher ductility. Under cyclic loading, the material's behaviour at large numbers of cycles was independent of specimen size, but the microscopic specimens were inferior at smaller numbers of cycles to failure. Fatigue limits for the notched specimens could be predicted using an existing theory (the Theory of Critical Distances) but parameter values were different at the macro- and micro-scale. Thus, data from conventional, macroscopic specimens cannot be used to predict the behaviour of this material when used for microscopic components. Mechanical working and annealing strongly affected the tensile strength and ductility, but had no significant effect on fatigue behaviour. Show more

Keywords: Strength, ductility, fatigue, stainless steel, stents, stress concentrations

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 2, pp. 137-146, 2006

Authors: Pulat, Mehlika | Ekmekci, Ayhan | Aslim, Belma

Article Type: Research Article

Abstract: Polyurethane (PU) based hydrophobic and hydrophilic disks were prepared by graft copolymerization of PU with vinyl monomers, acryl amid (AAm), itaconic acid (IA), acrylic acid (AA) and crotonic acid (CA). Grafting reactions were performed in PU–dioxane solution using benzoyl peroxide as initiator. Air–water and cyclohexan–water contact angle values of the disks (θair and θcy ) were measured via “Captive Bubble Method”. Surface free energy values of the disks were determined by using θair and θcy via “Two Liquid Method” and those were compared with the swelling percentage values of the disks. The release of Bovine Serum Albumin …(BSA) from protein added hydrophilic and hydrophobic PU disks were defined by spectrophotometric measurements at λ=278 nm in phosphate buffer saline (PBS). BSA releasing is completed around 48 h for all disks. The disks were also characterized by FTIR spectra and SEM micrographs. In vitro attachment of Candida albicans (C. albicans) and Lactobacillus plantarum (L. plantarum) on PU based hydrophilic and hydrophobic disks was studied at 37°C. While C. albicans attached on to all disks, L. plantarum only selectively attached. The attachment percentage values of C. albicans (25%) and L. plantarum (20%) on hydrophobic PU disk were higher than hydrophilic PU disks. The antimicrobial activity of disks was also tested against C. albicans and L. plantarum. IA and AAm grafted PU disks showed inhibitory effect for the both test bacteria. Show more

Keywords: Polyurethane, bovine serum albumin, graft copolymerization, acryl amid, itaconic acid, acrylic acid, crotonic acid, contact angle, surface free energies, attachment, inhibition zone, Lactobacillus plantarum, Candida albicans

Citation: Bio-Medical Materials and Engineering, vol. 16, no. 2, pp. 147-156, 2006