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Biodegradation of 3D printed composites based on poly(3-hydroxybutyrate)
Gazdová, Nikol ; Menčík, Přemysl (referee) ; Melčová, Veronika (advisor)
This bachelor thesis deals with the biodegradation of 3D printed bodies composed of poly(3- hyroxybutyrate), polylactic acid, bioceramics and plasticizer. These components were selected for their biocompatibility and properties that could be used in tissue engineering as a temporary, absorbable bone tissue replacement. The main objective was to investigate the effect of the individual constituent bodies on the biodegradation itself. Biodegradation was carried out at 37 °C in a solution simulating the ionic concentration of blood plasma. Samples were sequentially withdrawn at monthly intervals for five months. To evaluate the results, 2 methods were used, weight change and compression test, where the strength of each body was evaluated. From the evaluation of the data it was not possible to reach a uniform result on which substance influences biodegradation the most, because it always depended on the ratio of the other substances. To investigate the effect of poly(3-hydroxybutyrate) and polylactic acid on the rate of biodegradation, mixtures of RP9, RP10 and RP15 were compared. It showed that a higher polylactic acid and lower poly(3-hydroxybutyrate) content had a significant positive effect on the biodegradation rate, as the difference between the weight loss for the RP9 blend with the highest poly(3-hydroxybutyrate) content and the RP10 blend with the highest polylactic acid content was 8.37% for solid bodies and 4.13% for porous bodies. For strength, the difference was 73.32% and 73.65% for the solid and porous bodies, respectively. Observing the effect of bioceramic content on the RP11, RP12 and RP15 mixtures, we concluded that this effect was almost negligible on the biodegradation rate The difference in weight loss between the RP11 mixture with the lowest bioceramic content and the RP12 mixture with the highest bioceramic content was only 1, 68 % for solid bodies and 0.99 % for porous bodies, while mixture RP15 showed the highest biodegradation rate despite having a medium value of bioceramics in the mixture. For the mechanical properties, this then amounts to a difference of 10.4% for the solids and 7.57% for the porous bodies. When comparing the effect of plasticizer for mixes RP13, RP14 and RP15, the effect was more on the strength drop, where the difference in strength drop for mix RP13 with the lowest plasticizer content and RP14 with the highest plasticizer content was different by 20.3% and 18.16% for the solid and porous body, respectively. The decrease in weight was then different by 4.1 % and 0.83 % for the solid and porous body, respectively. Finally, bioceramics from different companies emerged as an important element for the biodegradation rate. Hydroxyapatite from Applichem was the best biodegraded and hydroxyapatite from CN Lab was the worst. The difference for weight loss was 17.35% for the solid and 5.93% for the porous body. The strength loss was then different by 55.6% for the solid body and 33.38% for the porous body.
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