Bio-Medical Materials and Engineering - Volume 24, issue 5

Authors: Li, Jianhua

Article Type: Research Article

Abstract: For portable oxygen concentrator by pressure swing adsorption (PSA) method, its volume, mass, power, oxygen flux and oxygen saving efficiency are the most important parameters which are affected strongly by the PSA cycle. In this paper, we propose a new pressure equalization step to optimize the PSA cycle. According to the experimental results, when the product ends of two beds are connected and the feed gas is switched from the high pressure bed to the low pressure bed during the pressure equalization step, the system has a larger oxygen flux, a less energy consumption and a more simple structure.

Keywords: Cycle, operation pressure, portable oxygen concentrator, pressure swing adsorption

DOI: 10.3233/BME-140988

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 5, pp. 1771-1779, 2014

Authors: Melero, H. | Garcia-Giralt, N. | Fernández, J. | Díez-Pérez, A. | Guilemany, J.M.

Article Type: Research Article

Abstract: Hydroxyapatite coatings obtained by plasma-spraying have been used for many years to improve biological performance of bone implants, but several studies have drawn attention to the problems arising from high temperatures and the lack of mechanical properties. In this study, plasma-spraying is substituted by high velocity oxy-fuel (HVOF) spray, with lower temperatures reached, and TiO2 is added in low amounts to hydroxyapatite in order to improve the mechanical properties. Four conditions have been tested to evaluate which are those with better biological properties. Viability and proliferation tests, as well as differentiation assays and morphology observation, are performed with …human osteoblast cultures onto the studied coatings. The hydroxyapatite–TiO2 coatings maintain good cell viability and proliferation, especially the cases with higher amorphous phase amount and specific surface, and promote excellent differentiation, with a higher ALP amount for these cases than for polystyrene controls. Observation by SEM corroborates this excellent behaviour. In conclusion, these coatings are a good alternative to those used industrially, and an interesting issue would be improving biological behaviour of the worst cases, which in turn show the better mechanical properties. Show more

Keywords: Bio-ceramic, coating, in vitro behaviour, thermal spray, HVOF

DOI: 10.3233/BME-140989

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 5, pp. 1781-1791, 2014

Authors: Ozeki, K. | Goto, T. | Aoki, H. | Masuzawa, T.

Article Type: Research Article

Abstract: Hydroxyapatite (HA) thin films were prepared on a zirconia (ZrO2 ) substrate using a sputtering technique, and the film was also coated on a titanium (Ti) substrate for comparison. The coated films were recrystallised using a hydrothermal treatment to reduce film dissolution. The films were then characterised by X-ray diffractometry (XRD) and scanning electron microscopy (SEM). The osteocompatiblity of the films was evaluated by investigating the alkaline phosphatase (ALP) activity and the size of the bone formation area of osteoblast cells. In the XRD patterns of the as-sputtered films on the ZrO2 substrate, there are no peaks except …for those from the ZrO2 substrate. After the hydrothermal treatment, HA peaks appeared in the patterns. Nanoparticles (less than 20 nm) were observed on the ZrO2 substrates in the SEM images of the as-sputtered films. After the hydrothermal treatment, particles of 20–40 nm were observed on the film, whereas the HA film on the Ti substrate was covered by a larger number of globular particles (20–60 nm). In the osteoblast cell cultures, the ALP activity and bone formation area on the HA films on both the ZrO2 and Ti substrates increased after the hydrothermal treatment of the films, and the values for the ZrO2 substrate were higher than those for the Ti substrate. Show more

Keywords: Sputtering, hydroxyapatite, zirconia, titanium, osteoblast cell

DOI: 10.3233/BME-140990

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 5, pp. 1793-1802, 2014

Authors: Yourek, Gregory | Xin, Xuejun | Reilly, Gwendolen C. | Mao, Jeremy J.

Article Type: Research Article

Abstract: BACKGROUND: Attachment of cells to fully hydrated hydrogel biomaterials, such as PEGDA, has proven challenging because of the hydrophobic cellular membrane. OBJECTIVE: To demonstrate undifferentiated human mesenchymal stem cells (hMSCs) and hMSC-derived chondrocytes infiltrated and attached to unmodified PEGDA hydrogel. METHODS: Human MSCs and MSC-Cys were cultured in and on PEGDA hydrogel. Attachment was verified by SEM and confocal microscopy and was accompanied by vinculin expression, indicating the presence of focal contacts. Infiltration was confirmed by H&E and fluorescence staining. RESULTS: Cells cultured on top of PEGDA hydrogel infiltrated the material on the order of micrometers. …CONCLUSIONS: These findings will aid in understanding the cell-scaffold interaction for regenerative medicine constructs. Show more

Keywords: Mesenchymal stem cells, PEGDA, vinculin, differentiation, chondrogenesis, infiltration

DOI: 10.3233/BME-140991

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 5, pp. 1803-1815, 2014

Authors: Munar, Girlie M. | Munar, Melvin L. | Tsuru, Kanji | Ishikawa, Kunio

Article Type: Research Article

Abstract: The purpose of this study was to improve the mechanical property of brittle carbonate apatite (CO3 Ap) foam aimed as bone substitute material by reinforcement with poly(DL-lactide-co-glycolide) (PLGA). The CO3 Ap foam was reinforced with PLGA by immersion and vacuum infiltration methods. Compressive strength of CO3 Ap foam (12.0±4.9 kPa) increased after PLGA reinforcement by immersion (187.6±57.6 kPa) or vacuum infiltration (407.0±111.4 kPa). Scanning electron microscopic (SEM) observation showed a gapless PLGA and CO3 Ap foam interface and larger amount of PLGA inside the hollow space of the strut when vacuum infiltration method was employed. In contrast a gap was …observed at the PLGA and CO3 Ap foam interface and less amount of PLGA inside the hollow space of the strut when immersion method was employed. Strong PLGA–CO3 Ap foam interface and larger amount of PLGA inside the hollow space of the strut is therefore the key to higher mechanical property obtained for CO3 Ap foam when vacuum infiltration was employed for PLGA reinforcement. Show more

Keywords: Carbonate apatite foam, PLGA, bone substitute, immersion, vacuum infiltration

DOI: 10.3233/BME-140992

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 5, pp. 1817-1825, 2014

Authors: Pečlin, Polona | Bizjak, Milan | Ribarič, Samo | Rozman, Janez

Article Type: Research Article

Abstract: OBJECTIVE: The objective of this study was to investigate the structural properties of a cold-rolled platinum foil used to manufacture multi-electrode spiral nerve cuffs. METHODS: To attain this objective, 0.03-mm-thick cold-rolled platinum foil strips with 99.99 wt% purity were used. The resistivity measurements were made using a 4-point probe technique in which the strips were subjected to dynamic annealing in an argon atmosphere. The stored energy of platinum was recorded in an argon atmosphere using differential scanning calorimetry (DSC). Finally, the microstructure of the strips was investigated by optical microscopy. RESULTS: In the resistivity measurements, a small change …is observed at ~280°C. This change could be explained as the partial recovery elicited by the decrease of dislocation density. Above 500°C, a significant decrease in resistivity was recorded, and the decrease reached a maximum at ~750°C. These results are consistent with the recrystallization trend detected in DSC, namely the DSC measurement detected very weak heat release during recrystallization, which was actually accumulated during the cold-working. This exothermal peak occurred in the temperature range 380–800°C. Show more

Keywords: Nerve stimulation, platinum electrodes, annealing, recrystallization, microstructure, resistivity, optical microscopy, differential scanning calorimetry (DSC)

DOI: 10.3233/BME-140993

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 5, pp. 1827-1835, 2014

Authors: Hu, Tingzhang | Yang, Yongwei | Tan, Lili | Yin, Tieying | Wang, Yazhou | Wang, Guixue

Article Type: Research Article

Abstract: Polysaccharides, such as alginates, are already being used as carriers for drug delivery. The physicochemical and biological properties of alginates may be affected via irradiation and thermal treatments. To explore and compare effects of two kinds of sterilization methods, gamma irradiation and moist heat, on sodium alginate (SA), physicochemical and biological properties of SA powder and solutions were investigated after sterilization. Human umbilical vein endothelial cells (HUVEC) was used to assess the cytotoxicity of the SA after sterilization. The research showed that 25 kGy gamma ray can effectively sterilize microorganism. Both gamma irradiation and moist heat hardly affect the native …pH of SA. Compared to irradiation sterilization, moist heat sterilization showed smaller changes in intrinsic viscosity for all SA samples and lead to less glycosidic bond breaking of SA powders. The moist heat sterilization can cause the main chain scission and double bonds formation of the SA solutions. Cytotoxicity studies demonstrated that sterilized SA powers and SA solutions treated by gamma ray sterilization can increase the viability of HUVEC. However, SA solutions treated by moist heat sterilization were found to present severe cytotoxicity. The research results may provide interesting future advancements toward the development of SA-based products for biomedical applications. Show more

Keywords: Sodium alginate, sterilization, gamma ray, moist heat

DOI: 10.3233/BME-140994

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 5, pp. 1837-1849, 2014

Authors: Zhao, Xueni | He, Jianpeng | Zhang, Jing | Wang, Xudong | Wang, Wanying

Article Type: Research Article

Abstract: Nanostructured calcium phosphate/collagen (CaP/COL) coatings were deposited on the carbon/carbon (C/C) composites through electrochemical deposition (ECD) under magnetic field. The effect of magnetic fields with different orientations on the morphology and composition was investigated. Both the morphology and composition of the coatings could be altered by superimposed magnetic field. Under zero magnetic field and magnetic field, three-dimensional network structure consisting of collagen fibers and CaP were formed on the C/C substrate. The applied magnetic field in the electric field helped to form nanostructured and plate-like CaP on collagen fibers. For the ECD under magnetic field, the Ca/P molar ratio of …the coatings was lower than the one under B=0. This may be contributed to the decreased electrical resistance or the increased electrical conductivity of electrolyte solutions under magnetic field. The nanosized CaP/COL coatings exhibited the similar morphology to the human bone and could present excellent cell bioactivity and osteoblast functions. Show more

Keywords: Electrochemical deposition, magnetic field, coating, collagen, carbon/carbon composites

DOI: 10.3233/BME-140995

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 5, pp. 1851-1859, 2014

Authors: Gülsoy, H. Özkan | Gülsoy, Nagihan | Calışıcı, Rahmi

Article Type: Research Article

Abstract: Titanium and Titanium alloys exhibits properties that are excellent for various bio-applications. Metal injection molding is a processing route that offers reduction in costs, with the added advantage of near net-shape components. Different physical properties of Titanium alloy powders, shaped and processed via injection molding can achieve high complexity of part geometry with mechanical and bioactivity properties, similar or superior to wrought material. This study describes that the effect of particle morphology on the microstructural, mechanical and biocompatibility properties of injection molded Ti–6Al–4V (Ti64) alloy powder for biomaterials applications. Ti64 powders irregular and spherical in shape were injection molded with …wax based binder. Binder debinding was performed in solvent and thermal method. After debinding the samples were sintered under high vacuum. Metallographic studies were determined to densification and the corresponding microstructural changes. Sintered samples were immersed in a simulated body fluid (SBF) with elemental concentrations that were comparable to those of human blood plasma for a total period of 15 days. Both materials were implanted in fibroblast culture for biocompatibility evaluations were carried out. The results show that spherical and irregular powder could be sintered to a maximum theoretical density. Maximum tensile strength was obtained for spherical shape powder sintered. The tensile strength of the irregular shape powder sintered at the same temperature was lower due to higher porosity. Finally, mechanical tests show that the irregular shape powder has lower mechanical properties than spherical shape powder. The sintered irregular Ti64 powder exhibited better biocompatibility than sintered spherical Ti64 powder. Results of study showed that sintered spherical and irregular Ti64 powders exhibited high mechanical properties and good biocompatibility properties. Show more

Keywords: Sintering, powder injection molding, titanium alloy, biocompatibility

DOI: 10.3233/BME-140996

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 5, pp. 1861-1873, 2014

Authors: Teong, Benjamin | Kuo, Shyh-Ming | Chen, Chung-Hwan | Chen, Yu-Kuei | Cheng, Zhi-Jiao | Huang, Han Hsiang

Article Type: Research Article

Abstract: DMPC and DSPC liposomes were prepared via thin film hydration method followed by sonication. Propranolol solution was incorporated into liposomes at hydration stage. TEM images showed the sizes of DSPC and DMPC were around 88 and 137 nm, respectively. The highest encapsulation ratio of propranolol was approximately 70% using DSPC/CHO/OCT liposomes, which release the drug over 60% in 24 h and reached 100% in 48 h. Both propranolol (10−8 –10−6 M) and DSCP liposomes-encapsulated propranolol showed over 1.5-fold increases in the proliferation of human osteoblastic cells hFOB1.19 while differentiation of the cells was approximately doubled by plain and liposomal …propranolol, indicating that the stimulatory effects of liposomal propranolol are similar with those of propranolol on human osteoblastic hFOB1.19 cells. The phosphatidylcholine liposomes-encapsulated propranolol prepared in this study potentially possesses anabolic effects in vivo and is also a promising anti-osteoporotic agent in future. Show more

Keywords: Propranolol, DMPC, DSPC, liposome, human osteoblastic cells, drug delivery system

DOI: 10.3233/BME-140997

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 5, pp. 1875-1887, 2014