Composites made of resorbable polylactide modified with bone powder are part of the current search for implantable materials endowed with advantageous biomechanical functions, which make them suitable for orthopedics and traumatology applications. The bone additive containing active bone morphogenetic proteins (BMPs) and calcium phosphates introduced into the polymer matrix is to grant the implant with a biological activity. Subsequently, the resorbable matrix should get replaced with bone tissue. In order to avoid losing the osteoinductive properties of the designed material, it should be processed at low temperatures via physicochemical methods. This paper is devoted to the preparation and optimization of the composite production method suitable for biodegradable polymers and morphogenetic proteins along with the assessment of biocompatibility and biological properties of obtained materials. The tape-casting method was successfully applied. Resorbable polymer (medical poly-L-lactide, Purasorb PL38 by Purac) with 15 wt% of human bone powder (from tissue bank) were used to fabricate PLA-CP/BMPs composite implants. They were tested in in vivo studies that were performed in rabbit bone tissues. The results show a high biocompatibility of the material and good osteointegration with bone tissue.
Sandwich-type composite materials of various geometries were obtained, in which the inner layer was a laminate of glass fabric, and the core consisted of natural materials: balsa wood, coconut and sisal fibres. The materials were tested to determine the type of cracking process under static and dynamic stress conditions (impact strength). The best results were obtained for hybrid balsa/glass fabric composites with a spacer made of sisal mat. This type of system allows a controlled cracking process, which is a consequence of a different stress distribution. The research shows that the combination of different materials in a single composite, depending on their volume fraction, density and layering geometry, opens the way for use in technical constructions, especially where high specific strength is required. The work contains valuable results of research on sandwich materials, their behaviour under load, their modification, and their impact on the transfer of dynamic and static stresses. For the first time, a composition was tested containing a balsa tree core with transient elastic layers made of natural cellulose fibres.
Polysaccharides, such as chitosan (CS), are widely used in many biomedical applications. However, they require crosslinking agents to achieve chemical stability and appropriate mechanical properties. In this work, chitosan-based hydrogels were crosslinked using vanillin and/or sodium tripolyphosphate, as chemical and physical crosslinking agents, respectively. Microstructural (digital microscope, SEM), structural (FTIR-ATR), mechanical (static compression test), and in vitro biological (chemical stability and swelling ratio in PBS, cytotoxicity) properties of the obtained materials were evaluated to assess materials potential as biomedical scaffolds. The optimal ratio of vanillin to chitosan (DD = 89%) to crosslink the polymer was found to be 1.2:1. Moreover, the double crosslinking with vanillin caused a two-time increase in the compression strength of the samples and led to the slower biodegradability. Cytotoxicity studies showed that the cells prefer double vanillin crosslinked hydrogels over those treated with TPP. Further studies, such as bioactivity are required to determine the specific functionality of the hydrogels and the specific tissue which may be treated with the tested materials. The optimal material was chosen to the next step of the study, which may be obtaining composite hydrogels with hydroxyapatite and/or graphene oxide to tailor or improve properties towards specific tissue regeneration.