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Volksliederen --- België --- 20e eeuw

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A defining trend in today’s society is the ageing population. It causes a lot of problems that challenge the medical and technical sector. One of the issues is the more prevalent presence of osteoporosis in the older population group. The traditional way of using autografts or allografts as a treatment is not sustainable anymore as the demand transcends the supply on the donor market. A solution can be found in tissue engineering. In essence, grafts are used that mimic the native tissue to induce regeneration of that tissue. The objective of this thesis was the production of a material consisting of polylactic acid nanofibers (PLA-NF) embedded with poly(lactic-co-glycolic acid) microspheres (PLGA-MS). On top of that, there were experiments to determine its behaviour in media that simulate the inside of the human body. The production of fibers was via electrospinning and the spheres via electrospraying. A setup was organised to combine the two. Different samples were investigated to determine the influence of parameters on the morphologies of outgoing structures. For electrospinning, both a decrease in concentration of polymer solution and flow rate led to a decrease of the fiber diameter. However, both of them needed to stay within an appropriate span to form homogeneous fibers. There was also the drum speed, where a higher amount of rotations per minute (rpm) led to more homogeneous fibers. At the end, PLA-NF were produced at 30 kV, 10 w/v% and 300 rpm. For electrospraying, an increase in the concentration of the polymer solution caused a small increase in size of the MS. The influence of flow rate was also tested. It showed that an increase in the parameter led to more spheres. Again, it was important to keep the value of both parameters within a certain range to ensure the correct morphology of smooth spheres. Eventually, PLGA-MS at 7.5 w/v% and at 0.3 ml/hr were produced in larger quantities to investigate further. When combining the two structures, parameters were once more varied to test their influence. It showed that changing parameters of electropinning not only influenced the fibers, but also the spheres. Same for electrospraying, it affected both structures. As an illustration: a voltage of 25 kV showed a larger amount of spheres, and they were more homogeneous than at 30 kV. At the end, samples for long duration were made. For electrospinning they had the following attributes: 10 w/v% PLA solution, 1 ml/hr and 30 kV. For electrospraying: 7.5 w/v% PLGA solution, 0.3 ml/hr and 25 kV. The drum speed was 300 rpm for both. Removal of the samples of aluminium foil was not possible for the samples of solely PLGA-MS. Thus, they were not included in further tests. A mass loss test was executed where samples were submerged in a phosphate-buffered saline (PBS) solution for different periods of time, up to four weeks. PLA-NF showed little mass loss, while the combination of PLA-NF and PLGA-MS showed a more linear degradation over time. This is due to the presence of PLGA-MS. They dissolve over time in the buffer solution. It presents opportunities of incorporating drugs and/or bioactive factors in those spheres as they can release them over a period of time. It opens doors to scaffolds existing of PLA-NF providing structure around which bone tissue can regenerate while the embedded MS deliver products enhancing the healing process. In vitro tests for mineralisation were executed by investigating hydroxyapatite (HA) formation on samples