Abstract
This study reports on the processing of three-dimensional (3D) chitosan/bioactive glass composite scaffolds. On the one hand, chitosan, as a natural polymer, has suitable properties for tissue engineering applications but lacks bioactivity. On the other hand, bioactive glasses are known to be bioactive and to promote a higher level of bone formation than any other biomaterial type. However, bioactive glasses are hard, brittle, and cannot be shaped easily. Therefore, in the past years, researchers have focused on the processing of new composites. Difficulties in reaching composite materials made of polymer (synthetic or natural) and bioactive glass include: (i) The high glass density, often resulting in glass segregation, and (ii) the fast bioactive glass reaction when exposed to moisture, leading to changes in the glass reactivity and/or change in the polymeric matrix. Samples were prepared with 5, 15, and 30 wt% of bioactive glass S53P4 (BonAlive ®), as confirmed using thermogravimetric analysis. MicrO–Computed tomography and optical microscopy revealed a flaky structure with porosity over 80%. The pore size decreased when increasing the glass content up to 15 wt%, but increased back when the glass content was 30 wt%. Similarly, the mechanical properties (in compression) of the scaffolds increased for glass content up to 15%, but decreased at higher loading. Ions released from the scaffolds were found to lead to precipitation of a calcium phosphate reactive layer at the scaffold surface. This is a first indication of the potential bioactivity of these materials. Overall, chitosan/bioactive glass composite scaffolds were successfully produced with pore size, machinability, and ability to promote a calcium phosphate layer, showing promise for bone tissue engineering and the mechanical properties can justify their use in non-load bearing applications.
Highlights
The S53P4 bioactive glass has a nominal composition of 53% SiO2, 4% P2O5, 23% Na2O, and 20% CaO, and has been cleared for clinical use by the Food and Drug Administration (FDA) [1,2]
The pure chitosan solution was labeled as 0 wt% and the composites were labeled based on their glass content
20 ± 3% of the original mass of the neat chitosan scaffold was left after the heating cycle, which accounted for the char remaining in the alumina crucible
Summary
The S53P4 bioactive glass has a nominal composition (in wt%) of 53% SiO2, 4% P2O5, 23% Na2O, and 20% CaO, and has been cleared for clinical use by the Food and Drug Administration (FDA) [1,2]. Studies by Lindfors et al on the implantation of large bioactive glass particles (1–4 mm) revealed that some material remained undissolved at the surgical site even at 14 years post-surgery [4]. Studies on chitosan-ceramic biocomposites have emerged, demonstrating that the combination of a natural polymer with an osteoconductive ceramic holds promise for bone tissue engineering [9]. Chitosan/bioactive glass composites were prepared and characterized as potential biomaterials in bone tissue engineering. The use of melt-derived glass particles is of particular interest since it reduces the risk of fast glass dissolution, provides a sustained ion release, while enabling one to have higher ability to tune the glass compositions based on the aimed application. The mechanical properties of the composite were measured in compression
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