Study on ßTCP/P(3HB) Scaffolds-Physicochemical Properties and Biological Performance in Low Oxygen Concentration.

The search for new materials for bone regenerative purposes is still ongoing. Therefore, we present a series of newly constructed composites based on ß tricalcium phosphate (ßTCP) and poly(3-hydroxybutyrate) bacteria-derived biopolymer (P(3HB)) in the form of 3D scaffolds with different pore sizes. To improve the polymer attachment to the ßTCP surface, the etching of ceramic sinters, using citric acid, was applied. As expected, pre-treatment led to the increase in surface roughness and the creation of micropores facilitating polymer adhesion. In this way, the durability and compressive strength of the ceramic-polymer scaffolds were enhanced. It was confirmed that P(3HB) degrades to 3-hydroxybutyric acid, which broadens applications of developed materials in bone tissue engineering as this compound can potentially nourish surrounding tissues and reduce osteoporosis. Moreover, to the best of our knowledge, it is one of the first studies where the impact of ßTCP/P(3HB) scaffolds on mesenchymal stem cells (MSCs), cultured in lowered (5%) oxygen concentration, was assessed. It was decided to use a 5% oxygen concentration in the culture to mimic the conditions that would be found in damaged bone in a living organism during regeneration. Scaffolds enabled cell migration and sufficient flow of the culture medium, ensuring high cell viability. Furthermore, in composites with etched ßTCP, the MSCs adhesion was facilitated by hydrophilic ceramic protrusions which reduced hydrophobicity. The developed materials are potential candidates for bone tissue regeneration. Nevertheless, to confirm this hypothesis, in vivo studies should be performed.

Silver Decorated ßTCP-Poly(3hydroxybutyrate) Scaffolds for Bone Tissue Engineering.

Implantations in orthopedics are associated with a high risk of bacterial infections in the surgery area. Therefore, biomaterials containing antibacterial agents, such as antibiotics, bactericidal ions or nanoparticles have been intensively investigated. In this work, silver decorated ß tricalcium phosphate (ßTCP)-based porous scaffolds were obtained and coated with a biopolymer-poly(3-hydroxybutyrate)-P(3HB). To the best of our knowledge, studies using silver-doped ßTCP and P(3HB), as a component in ceramic-polymer scaffolds for bone tissue regeneration, have not yet been reported. Obtained materials were investigated by high-temperature X-ray diffraction, X-ray fluorescence, scanning electron microscopy with energy dispersive spectroscopy, hydrostatic weighing, compression tests and ultrahigh-pressure liquid chromatography with mass spectrometry (UHPLC-MS) measurements. The influence of sintering temperature (1150, 1200 °C) on the scaffolds' physicochemical properties (phase and chemical composition, microstructure, porosity, compressive strength) was evaluated. Materials covered with P(3HB) possessed higher compressive strength (3.8 ± 0.6 MPa) and surgical maneuverability, sufficient to withstand the implantation procedures. Furthermore, during the hydrolytic degradation of the composite material not only pure (R)-3-hydroxybutyric acid but also its oligomers were released which may nourish surrounding tissues. Thus, obtained scaffolds were found to be promising bone substitutes for use in non-load bearing applications.

Physicochemical and Biological Characterisation of Diclofenac Oligomeric Poly(3-hydroxyoctanoate) Hybrids as ß-TCP Ceramics Modifiers for Bone Tissue Regeneration.

Nowadays, regenerative medicine faces a major challenge in providing new, functional materials that will meet the characteristics desired to replenish and grow new tissue. Therefore, this study presents new ceramic-polymer composites in which the matrix consists of tricalcium phosphates covered with blends containing a chemically bounded diclofenac with the biocompatible polymer-poly(3-hydroxyoctanoate), P(3HO). Modification of P(3HO) oligomers was confirmed by NMR, IR and XPS. Moreover, obtained oligomers and their blends were subjected to an in-depth characterisation using GPC, TGA, DSC and AFM. Furthermore, we demonstrate that the hydrophobicity and surface free energy values of blends decreased with the amount of diclofenac modified oligomers. Subsequently, the designed composites were used as a substrate for growth of the pre-osteoblast cell line (MC3T3-E1). An in vitro biocompatibility study showed that the composite with the lowest concentration of the proposed drug is within the range assumed to be non-toxic (viability above 70%). Cell proliferation was visualised using the SEM method, whereas the observation of cell penetration into the scaffold was carried out by confocal microscopy. Thus, it can be an ideal new functional bone tissue substitute, allowing not only the regeneration and restoration of the defect but also inhibiting the development of chronic inflammation.

Novel bioresorbable tricalcium phosphate/polyhydroxyoctanoate (TCP/PHO) composites as scaffolds for bone tissue engineering applications.

Development of new composite materials for bone tissue engineering is a constantly growing field of medicine. Therefore there is a continuous need in creating novel materials that can not only regenerate the defected tissue but also nourish it while the healing process progresses. Here we present a novel type of composite material that fulfils these requirements. The study describes creation of a composite with macroporous bioceramic core that is infiltrated with a thin biopolymer layer. The ceramic component, namely tricalcium phosphate (TCP), due to its mechanistic and bioactive properties may promote new bone creation as shown through the in vitro studies. To the best of our knowledge the coating layer was created for the first time from a representative of bacterially derived medium chain length polyhydroxyalkanoate polymers (mcl-PHA), namely polyhydroxyoctanoate (PHO). This polymer layer not only profoundly changed the stress-strain characteristics of the bioceramic foam but also released (R)-3-hydroxyacids and their dimers/trimers to the investigated environment. In the manuscript we have in depth characterised these materials employing a set of basic procedures, through 3D structure reconstruction and finishing with prolonged in vitro experiments.