Bio-Medical Materials and Engineering - Volume 17, issue 3

Authors: Chueh, Shang-kai | Tachibana, Yoichi | Uyama, Hiroshi | Kobayashi, Shiro | Tomita, Naohide

Article Type: Research Article

Abstract: Poly(N-substituted α/β-asparagine) was evaluated as a thermoresponsible and an injectable scaffold for cartilage regeneration. Solutions of this polymer are liquid state below 25°C and nonfluid hydrogel above 35°C, allowing an aqueous solution containing cells at room temperature to form a hydrogel with encapsulated cells at physiological body temperature. Chondrocytes were isolated from joint of 4-week-old Japanese white rabbits, dispersed within the thermoresponsive polymer solution and maintained for up to 72 hours in vitro. The polymer solutions demonstrated concentration-dependent inhibitory effect on chondrocytes multiplication. After the three-day cultivation, the survival rate of the chondrocytes fell into a 70~90% ranges among all …the tested polymer concentrations. The morphology studies showed that there were some physical and/or chemical stress leading cells to necrosis and some extent apoptosis. Some physical and/or chemical stress may be applied, and over 70% of the chondrocytes could survive through the stress, suggesting that some phenotype could have been selected from the heterogeneous mixture of chondrocytes. Show more

Keywords: Thermoresponsive polymer, injectable material, chondrocytes, cartilage, apoptosis

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 3, pp. 137-146, 2007

Authors: Leong, K.F. | Wiria, F.E. | Chua, C.K. | Li, S.H.

Article Type: Research Article

Abstract: Selective Laser Sintering (SLS), an established Rapid Prototyping (RP) process, is investigated for building controlled drug delivery devices (DDD). The drug and its matrix in a powder form were first mixed mechanically before being sintered on the SLS. Each cylindrical DDD is designed with a number of concentric rings separated from each other by a characteristic ‘wall’ created by the laser of the SLS. These rings act as diffusion obstacles to control the rate of release. Poly-ε-caprolactone (PCL) was used as the matrix and Methylene Blue (MB) as the drug model. Samples were built, characterized and tested for homogeneity using …Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and Fourier Transform Infrared Spectrophotometry (FTIR). Experimental results show that the matrices fabricated are not affected by sintering and the polymer and drug model are evenly distributed throughout the matrix. The initial burst effect has been reduced by the increase of the numbers of rings. The linear curve using the Higuchi equation confirmed that the DDD matrix release profile is by diffusion. These results show that the DDD matrix design has promising potential for application in controlled release drug delivery. Show more

Keywords: Drug delivery device, selective laser sintering, diffusion, poly-ε-caprolactone, Methylene Blue

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 3, pp. 147-157, 2007

Authors: Sethumadhavan, Rao | Taguchi, Tetsushi | Tanaka, Junzo | Tateishi, Tetsuya

Article Type: Research Article

Abstract: A novel tissue adhesive consisting of human serum albumin (HSA) and tartaric acid derivative (TAD) was developed by us. Four different concentrations of TAD namely, 0.05 mmol, 0.1 mmol, 0.2 mmol and 0.3 mmol were mixed with 40%, 42% and 44% HSA individually and were made in the form of disks. J774A.1 mouse macrophage cells were seeded on top of these disks. The disks were pre-treated with sterile water and Eagle's medium before every seeding. All the seeding was incubated from 1 day to 3 days before making any investigations on it. SEM images were recorded and it was observed …that these cells adhered to these materials very well. Nitric oxide activity was studied using nitrate/nitrite colorimetric assay method. It was observed that the total NO production is almost the same for 40% and 42% HSA for the respective concentrations of 0.05 mmol to 0.3 mmol TAD at all incubation times from 1 d to 3 d. On the other hand, the NO activity considerably decreases for 44% HSA at all concentrations from 0.05 to 0.3 mmol TAD. This trend is observed for all the three days of incubation. From the iNOS mRNA RT-PCR experiments, it was observed that no tendency of the gene expression of iNOS was significantly found and the expression level of this gene is not affected by the concentrations of both HSA and TAD. iNOS may be up-regulated by TAD in the early stage of culture (day 1) but no significant change was observed on day 2 and 3. On the whole 0.3 mmol TAD with 44% HSA could be considered as a challenging material as a tissue adhesive for use in the field of tissue engineering. Ours is the first report on iNOS gene expression on a tissue adhesive. Show more

Keywords: Tissue adhesive, TAD, SEM, iNOS, RT-PCR

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 3, pp. 159-168, 2007

Authors: Wenzel, S.A. | Shepherd, D.E.T.

Article Type: Research Article

Abstract: Total disc arthroplasty is gaining in popularity as an alternative to spinal fusion. A total disc consists of articulating bearing surfaces with one made from a metal and the other made from either a metal or a polymer. The aim of this study was to determine the contact stresses in lumbar total disc arthroplasty devices. The total disc was modelled as a ball and socket joint and Hertzian contact theory was used to determine the maximum contact stresses. The effect of material combination and implant size on contact stress was investigated. For a typical disc arthroplasty with a ball radius …of 14 mm, the contact stresses for metal against polymer and metal against metal material combinations were 3 to 6 MPa and 63–130 MPa, respectively, and were below the fatigue strength of the materials. Show more

Keywords: Cobalt chrome molybdenum alloy, disc arthroplasty, Hertzian, stress, ultra high molecular weight polyethylene

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 3, pp. 169-173, 2007

Authors: Ozeki, K. | Kobayashi, S. | Hirakuri, K.K. | Aoki, H. | Fukui, Y.

Article Type: Research Article

Abstract: Diamond-like carbon (DLC) films were deposited on ultra-high molecular weight polyethylene (UHMWPE) and polymethylmethacrylate (PMMA) with oxygen plasma pre-treatment using a radiofrequency plasma chemical vapour deposition method. A ball-on-disc test was carried out to evaluate the wear properties of the DLC-coated UHMWPE and PMMA. After testing, the surface of the polymers was observed using an atomic force microscope and an optical microscope. The adhesive strength of the DLC films deposited on the polymers was measured using a scratch test. After the ball-on-disc test, many cracks were observed in the films on the surface of both the DLC-coated UHMWPE and PMMA …without the oxygen plasma pre-treatment, whereas the DLC-coated UHMWPE and PMMA with oxygen plasma pre-treatment showed no cracks and good wear resistance. In the scratch test, the adhesion strength of the DLC film to the PMMA substrate increased from 42.5 mN to 101.3 mN with oxygen plasma pre-treatment. Show more

Keywords: Diamond-like carbon, ultra-high molecular weight polyethylene, polymethylmethacrylate, chemical vapour deposition, oxygen plasma, adhesion, wear property

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 3, pp. 175-182, 2007

Authors: Übeyli, Elif Derya

Article Type: Research Article

Abstract: This paper intends to an integrated view of the spectral analysis techniques in the detection of arterial disorders. The paper includes illustrative information about feature extraction from signals recorded from arteries. Short-time Fourier transform (STFT) and wavelet transform (WT) were used for spectral analysis of ophthalmic arterial (OA) Doppler signals. Using these spectral analysis methods, the variations in the shape of the Doppler spectra as a function of time were presented in the form of sonograms in order to obtain medical information. These sonograms were then used to compare the applied methods in terms of their frequency resolution and the …effects in determination of OA stenosis. The author suggest that the content of the paper will assist to the people in gaining a better understanding of the STFT and WT in the detection of arterial disorders. Show more

Keywords: Doppler ultrasound, short-time Fourier transform, wavelet transform, sonogram, ophthalmic artery stenosis

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 3, pp. 183-189, 2007

Authors: Sakai, Yoshihito | Matsuyama, Yukihiro | Takahashi, Katsuya | Sato, Tomoya | Hattori, Tatsuya | Nakashima, Shojiro | Ishiguro, Naoki

Article Type: Research Article

Abstract: For peripheral nerve regeneration, three-dimensional distribution and growth of cells within the porous scaffold are of clinical significance. We demonstrate that cultured rat Schwann cells and neurospheres grow in vitro on new artificial nerve conduits made with photocrosslinked hyaluronic acid (HA). HA tubular conduits have an inner diameter of 1.2 mm with porous nano-structure of 50 μm. After 3 weeks of cultivation, HA conduits remained circular with a round lumen, and construct of cell-conduits maintained the size and shape of the original architecture of the tube. HA itself has the function to facilitate a pathway for cellular and axonal ingrowth …during peripheral nerve regeneration. These findings provide the feasibility of using the HA conduits for better cell adhesion and differentiation, leading to axonal regeneration in peripheral nerve reconstruction. Show more

Keywords: Hyaluronic acid, photocrosslink, nerve conduit, nerve regeneration

Citation: Bio-Medical Materials and Engineering, vol. 17, no. 3, pp. 191-197, 2007