The increase of apatite layer formation by the poly(3-hydroxybutyrate) surface modification of hydroxyapatite and β-tricalcium phosphate

Development of Nonwoven Fibrous Materials Based on Poly-3-Hydroxybutyrate with a High Content of α-Tricalcium Phosphate

α-tricalcium (α-TCP) phosphate is widely used as an osteoinductive biocompatible material, serving as an alternative to synthetic porous bone materials. The objective of this study is to obtain a highly filled fibrous nonwoven material composed of poly-3-hydroxybutyrate (PHB) and α-TCP and to investigate the morphology, structure, and properties of the composite obtained by the electrospinning method (ES). The addition of α-TCP had a significant effect on the supramolecular structure of the material, allowing it to control the crystallinity of the material, which was accompanied by changes in mechanical properties, FTIR spectra, and XRD curves. The obtained results open the way to the creation of new osteoconductive materials with a controlled release of the source of calcium into the living organism.

Recent Progress in Polyhydroxyalkanoates-Based Copolymers for Biomedical Applications

In recent years, naturally biodegradable polyhydroxyalkanoate (PHA) monopolymers have become focus of public attentions due to their good biocompatibility. However, due to its poor mechanical properties, high production costs, and limited functionality, its applications in materials, energy, and biomedical applications are greatly limited. In recent years, researchers have found that PHA copolymers have better thermal properties, mechanical processability, and physicochemical properties relative to their homopolymers. This review summarizes the synthesis of PHA copolymers by the latest biosynthetic and chemical modification methods. The modified PHA copolymer could greatly reduce the production cost with elevated mechanical or physicochemical properties, which can further meet the practical needs of various fields. This review further summarizes the broad applications of modified PHA copolymers in biomedical applications, which might shred lights on their commercial applications.

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.

Development of dual delivery antituberculotic system containing rifapentine microspheres and adipose stem cells seeded in hydroxyapatite/tricalcium phosphate

Background

Low drug concentration in the tuberculosis (TB) lesion and bone defects or nonunion after debridement are two major problems that occur in the course of treating osteo-articular TB. Thus, the combination of drug-delivery system and bone tissue repair appears to be the most promising option for osteoarticular TB treatment.

Materials and methods

Herein, we report a novel anti-TB dual delivery system based on rifapentine polylactic acid microspheres (RPMs) to treat infections, with the addition of adipose-derived mesenchymal stem cells (ASCs) seeded in hydroxyapatite/tricalcium phosphate (HA/TCP) to promote bone formation. Cell proliferation, osteogenesis, and apoptosis were performed to investigate the effects of rifapentine on ASCs. The RPMs were synthesized by emulsion-solvent evaporation method, and then the monolayer composite (ASC + RPM) and three-dimensional (3D) composite scaffold (ASC + RPM + HA/TCP) were constructed, respectively. The alkaline phosphatase (ALP) activity and real-time PCR were used for determining the osteogenic differentiation. The concentrations of rifapentine resulting from the composites were detected.

Results

The results showed that rifapentine has no influence on ASCs proliferation and osteogenesis when the drug concentration was below 20 µg/mL, which was significantly higher than minimal inhibitory concentration. The drug loading and encapsulation efficiency of RPMs were 40.56%±2.63% and 70.24%±2.18%, respectively. The proliferation of the cells in monolayer was higher than that in 3D composite, and the addition of RPMs slightly increased the proliferation. The ALP activity and gene expression of osteocalcin and osteopontin were higher in the 3D composite than those in the monolayer. Good biocompatibility was observed by microscopic image and H&E stain. The release tests revealed that the 3D composite exhibited sustained release profiles of rifapentine for 76 days. The dual delivery systems in 3D composite could moderate the burst release and extend the length of release time when compared to single delivery in monolayers.

Conclusion

In conclusion, such dual delivery antituberculotic scaffold represents a potential new strategy for TB infections and bone defects.

Glycerol Salicylate-based Pulp-Capping Material Containing Portland Cement

The purpose of this study was to evaluate the water sorption, solubility, pH and ability to diffuse into dentin of a glycerol salicylate-based, pulp-capping cement in comparison to a conventional calcium hydroxide-based pulp capping material (Hydcal). An experimental cement was developed containing 60% glycerol salicylate resin, 10% methyl salicylate, 25% calcium hydroxide and 5% Portland cement. Water sorption and solubility were determined based on mass changes in the samples before and after the immersion in distilled water for 7 days. Material discs were stored in distilled water for 24 h, 7 days and 28 days, and a digital pHmeter was used to measure the pH of water. The cement's ability to diffuse into bovine dentin was assessed by Raman spectroscopy. The glycerol salicylate-based cement presented higher water sorption and lower solubility than Hydcal. The pH of water used to store the samples increased for both cements, reaching 12.59 ± 0.06 and 12.54 ± 0.05 after 7 days, for Hydcal and glycerol salicylate-based cements, respectively. Both cements were able to turn alkaline the medium at 24 h and sustain its alkalinity after 28 days. Hydcal exhibited an intense diffusion into dentin up to 40 µm deep, and the glycerol salicylate-based cement penetrated 20 µm. The experimental glycerol salicylate-based cement presents good sorption, solubility, ability to alkalize the surrounding tissues and diffusion into dentin to be used as pulp capping material.

The comparison study of bioactivity between composites containing synthetic non-substituted and carbonate-substituted hydroxyapatite

Apatite forming ability of hydroxyapatite (HAP) and carbonate hydroxyapatite (CHAP) containing composites was compared. Two composite materials, intended for filling bone defects, were made of polysaccharide polymer and one of two types of hydroxyapatite. The bioactivity of the composites was evaluated in vitro by soaking in a simulated body fluid (SBF), and the formation of the apatite layer was determined by scanning electron microscopy with energy-dispersive spectrometer and Raman spectroscopy. The results showed that both the composites induced the formation of apatite layer on their surface after soaking in SBF. In addition, the sample weight changes and the ion concentration of the SBF were scrutinized. The results showed the weight increase for both materials after SBF treatment, higher weight gain and higher uptake of calcium ions by HAP containing scaffolds. SBF solution analysis indicated loss of calcium and phosphorus ions during experiment. All these results indicate apatite forming ability of both biomaterials and suggest comparable bioactive properties of composite containing pure hydroxyapatite and carbonate-substituted one.

Fabrication and characterization of polymer–ceramic nanocomposites containing pluronic F127 immobilized on hydroxyapatite nanoparticles

Synthesis and embedding of HA-F127 nanoparticles into a PCL/P123 nanofibrous scaffold plus molecular dynamics simulation of pristine and modified HA/polymer interactions.

Hydroxyapatite-based materials of marine origin: a bioactivity and sintering study

Single phase hydroxyapatite (HAp) and biphasic material hydroxyapatite/β-tricalcium phosphate (HAp/β-TCP) were obtained from a marine source (Atlantic cod fish bones). Here we report a study on the biological properties of these materials, including cytotoxicity, bioactivity and haemocompatibility. Results showed that the materials are not cytotoxic, neither in their powder nor in pellet form; indeed growth of Saos-2 cells was comparable to that of commercial. The haemolysis rate was lower than 2%; hence the materials can be classified as non-haemolytic. Moreover, when immersed in Simulated Body Fluid (SBF), crystal formation was observed on the surface of both materials. The sintering behaviour of the samples was also studied; both powders showed very high sinterability (density higher than 95% of the theoretical value). Overall, these results confirm the suitability of these materials for biomedical applications.