[From Passive Application to Active Design -Restructuring and Reshaping of Core Specialty Knowledge Systems of Biomedical Engineering (Biomedical Materials Track) Undergraduate Education].

Biomedical engineering (BME) (biomedical materials track) is a typical field of interdisciplinary integration. Its specialty education simultaneously undertakes the duo reformation responsibilities for the new engineering education and the new medical education due to its unique strengths in interdisciplinary nature, comprehensive scope of knowledge, and status of being on the cutting edge of technology. We made an analysis, in this paper, of the opportunities and challenges faced by BME (biomedical materials track) specialty education on the basis of the trends and frontiers of development in biomedical materials in the world. From the perspective of new requirements raised by major national strategies and industrial development for the qualifications and competence of professionals specializing in biomedical materials, thorough reflections were made on the specialized education of BME (biomedical materials track) under the background of the new engineering education and the new medical education. Furthermore, we proposed herein to reconstruct the specialized core knowledge system according to the main line of the reactions and the responses between the biomedical materials and human bodies at different levels and set up a series of courses of biomedical materials science centered on Materiobiology as the core. We also proposed to establish a diversified integrated reform model of the training system incorporating production, learning, research and application for highly competent BME (biomedical materials track) professionals. This paper attempts to contribute to the solution of the major issue of how to train the innovative talents and leaders who will pioneer a new round of diagnosis and treatment technology revolution and the development of the medical device industry.

In vitro degradation of three-dimensional chitosan/apatite composite rods prepared via in situ precipitation.

Three-dimensional (3D) compact rods with multilayer structure made from chitosan (CHI) and apatite (Ap) have been prepared. The cytocompatibility assay revealed that the CHI/Ap composite could promote cell proliferation. In vitro degradation behaviors of the rods have been systematically investigated for up to 6 weeks in phosphate buffer saline (PBS) solution at 37°C. The properties of the composite rods were measured by means of weight loss, swelling ratio, and the changes in mechanical properties, etc. The pH of the PBS solution during the first 2 weeks of degradation was also detected. Results showed that the medium of CHI/Ap composite rods exhibited more stable pH change compared with that of CHI rods. Weight loss as well as the changes in mechanical properties happened more often to CHI rods than CHI/Ap rods. The presence of Ap could effectively reduce the degradation rate of the composite rods. All the results suggested that the composite rods could keep the initial shapes and mechanical properties longer than the pure CHI rods.

Fabrication of chitosan/hydroxylapatite composite rods with a layer-by-layer structure for fracture fixation.

A composite rod for fracture fixation using chitosan (CHI)/hydroxylapatite (HA) was prepared by means of in situ precipitation, which had a layer-by-layer structure, good mechanical properties, and cell compatibilities. The CHI/HA composite rods were precipitated from the chitosan solution with calcium and phosphorus precursors, followed by treatment with a tripolyphosphate-trisodium phosphate solution (pH >13) to crosslink the CHI and to hydrolyze the calcium phosphates to nanocrystalline HA. The results of FTIR, XRD, and TEM measurements confirmed that HA had been formed within the CHI matrix. The effects of the CHI/HA ratios (20/0, 20/1, 20/2, 20/4, and 20/5, w/w) on the mechanical properties were investigated. At the CHI/HA ratio of 20/4 (w/w), the bending strength and modulus of the rods were 133 MPa and 6.8 GPa, respectively. Pre-osteoblast MC3T3-E1 cells were cultured in an extract of the CHI/HA rods (20/4, w/w) to study the cell compatibilities of the composite. The observations indicated that the CHI/HA composite could promote the growth of MC3T3-E1 cells better than the composite without HA (p < 0.05). Furthermore, the co-cultivation of the cells and the CHI/HA composite showed that cells fully spread on the surface of the composite with an obvious cytoskeleton organization, which also revealed that the CHI/HA composite had a good biocompatibility.

Development of Fe3O4-poly(L-lactide) magnetic microparticles in supercritical CO2.

The Fe(3)O(4)-poly(L-lactide) (Fe(3)O(4)-PLLA) magnetic microparticles were successfully prepared in a process of solution-enhanced dispersion by supercritical CO(2) (SEDS), and their morphology, particle size, magnetic mass content, surface atom distribution and magnetic properties were characterized. Indomethacin (Indo) was used as a drug model to produce drug-polymer magnetic composite microparticles. The resulting Fe(3)O(4)-PLLA microparticles with mean size of 803 nm had good magnetic property and a saturation magnetization of 24.99 emu/g. The X-ray photoelectron spectroscopy (XPS) test indicated that most of the Fe(3)O(4) were encapsulated by PLLA, which indicated that the Fe(3)O(4)-PLLA magnetic microparticles had a core-shell structure. After further loading with drug, the Indo-Fe(3)O(4)-PLLA microparticles had a bigger mean size of 901 nm, and the Fourier transform infrared spectrometer (FTIR) analysis demonstrated that the SEDS process was a typical physical coating process to produce drug-polymer magnetic composite microparticles, which is favorable for drugs since there is no change in chemistry. The in vitro cytotoxicity test showed that the Fe(3)O(4)-PLLA magnetic microparticles had no cytotoxicity and were biocompatible, which means there is potential for biomedical application.

Study of poly(L-lactide) microparticles based on supercritical CO2.

Poly(L-lactide) (PLLA) microparticles were prepared in supercritical anti-solvent process. The effects of several key factors on surface morphology, and particle size and particle size distribution were investigated. These factors included initial drops size, saturation ratio of PLLA solution, pressure, temperature, concentration of the organic solution, the flow rate of the solution and molecular weight of PLLA. The results indicated that the saturation ratio of PLLA solution, concentration of the organic solution and flow rate of the solution played important roles on the properties of products. Various microparticles with the mean particle size ranging from 0.64 to 6.64 microm, could be prepared by adjusting the operational parameters. Fine microparticles were obtained in a process namely solution-enhanced dispersion by supercritical fluids (SEDS) process with dichloromethane/acetone mixture as solution.