Fabrication and properties of alginate/calcium phosphate hybrid beads: A comparative study

BACKGROUND

Microbeads for bone repair have been widely studied because they can be conveniently used in clinical applications.

OBJECTIVE

This study concerns the preparation, physical properties and in vitro characterisation of different types of alginate/calcium phosphate (CaP) ceramic microbeads, which were designed for use as drug delivery systems and bone-regeneration matrices.

METHODS

Hybrid microbeads were successfully prepared from sodium alginate and various CaP, namely 𝛼-tricalcium phosphate, 𝛽-tricalcium phosphate and hydroxyapatite using the liquid droplet method.

RESULTS

Porosity, swelling properties and in vitro degradation of the microbeads in the aqueous environment were significantly changed by the added CaP. The compressive strength of the blocks fabricated from the beads was around 120 MPa irrespective of the type of CaP. The initial release rate of the model drug methylene blue was suppressed by the addition of CaP.

CONCLUSION

The alginate-CaP composite beads hold promising potential as an encapsulation carrier of drugs and component of bone substitutes.

Preparation and Bioactivity Properties of a Novel Composite Membrane of Fructose Mediatedβ-Tricalcium Pyrophosphate/(Polyethylene Glycol/Chitosan) for Guided Tissue Regeneration

A novel composite membrane ofβ-tricalcium pyrophosphate (β-TCP) and fructose- (F-) mediated chitosan/poly(ethylene glycol) (CS/PEG) was prepared by thermally induced phase separation technique. The prepared composite membranes were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mechanical property, swelling, degradation, and cytotoxicity of the composite membranes were evaluated in vitro with respect to its potential for use as biodegradable guided tissue regeneration (GTR) membrane. In vitro degradation tests showed the composite membrane with a controllable degradation rate when changing theβ-TCP content. The incorporation ofβ-TCP granules also caused a significant enhancement of tensile strength. Whenβ-TCP content is controlled to 50 wt%, homogeneous composite membranes with well mechanical property and enzymatic degradation rate can be obtained. Cytotoxicity assay demonstrates that the composite membranes were nontoxic and had very good cell compatibility. Most importantly, the release of calcium ions and glucosamine from the composite membranes was proved to increase the cell proliferation of NIH3T3. The results of this study have indicated that this novel F-β-TCP/CS/PEG composite can be a suitable material for GTR applications.

Preparation and evaluation of collagen I/ gellan gum/β-TCP microspheres as bone graft substitute materials

Collagen I is the main component of protein in bone and exhibits many excellent applications in biomedical fields. Gellan gum possesses good biocompatible, biodegradable and good mechanical property, and shows great potentials as tissue engineering scaffold or cell culture substrate. Therefore, the aim of this study was to use collagen I, gellan gum and β-TCP to prepare collagen I/gellan gum/β-TCP microspheres by emulsion method as bone graft substitute materials. The preliminary results showed that collagen I/gellan gum/β-TCP microspheres had particle size distribution between 500-1000 µP in diameter and exhibited better mechanical strength. These microspheres also showed good biocompatibility in cell activity test.

Fabrication aspects of PLA-CaP/PLGA-CaP composites for orthopedic applications: a review

For several decades, composites made of polylactic acid-calcium phosphates (PLA-CaP) and polylactic acid-co-glycolic acid-calcium phosphates (PLGA-CaP) have seen widespread uses in orthopedic applications. This paper reviews the fabrication aspects of these composites, following the ubiquitous materials science approach by studying "processing-structure-property" correlations. Various fabrication processes such as microencapsulation, phase separation, electrospinning, supercritical gas foaming, etc., are reviewed, with specific examples of their applications in fabricating these composites. The effect of the incorporation of CaP materials on the mechanical and biological performance of PLA/PLGA is addressed. In addition, this paper describes the state of the art on challenges and innovations concerning CaP dispersion, incorporation of biomolecules/stem cells and long-term degradation of the composites.

A PERSPECTIVE VIEW ON THE PREPARATION OF MICRO- AND NANOPARTICULATES OF BIOMATERIALS FROM ELECTROSTATIC AND ULTRASONIC METHODS

Developments on tissue engineering, especially on tissue regeneration and drug delivery, demand also developments on biomaterials. Research on the preparation methods of biomaterials has exhibited remarkable advances in the recent years. Natural biomaterials, such as chitosan and collagen, or synthetic materials like poly(lactic acid) can be shaped in various forms. The parameters involved in the fabrication processes provide methodologies for control of the materials' properties, such as morphology, biodegradability, mechanical strength, and adhesion. As new applications develop for these materials, the preparation methods have to be optimized to achieve the desired material properties. These properties mostly not only mimic the conditions in the human body, but also may divert the microenvironment of cells in the diseased area in order to promote faster or guided healing and tissue regeneration. This review pays attention on some of the fabrication methods for biomaterial particulates of sizes in the micro- and nanoscale. The views expressed here focus on the many years of experience of the authors with electrostatic and ultrasonic fabrication methods. These methods are still under development and up to now can produce particulates of various sizes down to the nanometer scale with narrow size distributions. Such biomaterials that have extraordinary properties may provide ways for the development of remarkable biomedical applications.

Eco-Challenges of Bio-Based Polymer Composites

In recent years bio-based polymer composites have been the subject of many scientific and research projects, as well as many commercial programs. Growing global environmental and social concern, the high rate of depletion of petroleum resources and new environmental regulations have forced the search for new composites and green materials, compatible with the environment. The aim of this article is to present a brief review of the most suitable and commonly used biodegradable polymer matrices and NF reinforcements in eco-composites and nanocomposites, with special focus on PLA based materials.