Effects of heat treatment of wood on hydroxylapatite type mineral precipitation and biomechanical properties in vitro

Wood as Possible Renewable Material for Bone Implants-Literature Review

Bone fractures and bone defects affect millions of people every year. Metal implants for bone fracture fixation and autologous bone for defect reconstruction are used extensively in treatment of these pathologies. Simultaneously, alternative, sustainable, and biocompatible materials are being researched to improve existing practice. Wood as a biomaterial for bone repair has not been considered until the last 50 years. Even nowadays there is not much research on solid wood as a biomaterial in bone implants. A few species of wood have been investigated. Different techniques of wood preparation have been proposed. Simple pre-treatments such as boiling in water or preheating of ash, birch and juniper woods have been used initially. Later researchers have tried using carbonized wood and wood derived cellulose scaffold. Manufacturing implants from carbonized wood and cellulose requires more extensive wood processing-heat above 800 °C and chemicals to extract cellulose. Carbonized wood and cellulose scaffolds can be combined with other materials, such as silicon carbide, hydroxyapatite, and bioactive glass to improve biocompatibility and mechanical durability. Throughout the publications wood implants have provided good biocompatibility and osteoconductivity thanks to wood's porous structure.

Biodegradable and Non-Biodegradable Biomaterials and Their Effect on Cell Differentiation

Biomaterials for tissue scaffolds are key components in modern tissue engineering and regenerative medicine. Targeted reconstructive therapies require a proper choice of biomaterial and an adequate choice of cells to be seeded on it. The introduction of stem cells, and the transdifferentiation procedures, into regenerative medicine opened a new era and created new challenges for modern biomaterials. They must not only fulfill the mechanical functions of a scaffold for implanted cells and represent the expected mechanical strength of the artificial tissue, but furthermore, they should also assure their survival and, if possible, affect their desired way of differentiation. This paper aims to review how modern biomaterials, including synthetic (i.e., polylactic acid, polyurethane, polyvinyl alcohol, polyethylene terephthalate, ceramics) and natural (i.e., silk fibroin, decellularized scaffolds), both non-biodegradable and biodegradable, could influence (tissue) stem cells fate, regulate and direct their differentiation into desired target somatic cells.

Blood compatibility of iron-doped nanosize hydroxyapatite and its drug release

Nanosize hydroxyapatite (nHAp) doped with varying levels of Fe(3+) (Fe-nHAp of average size 75 nm) was synthesized by hydrothermal and microwave techniques. The samples were characterized for physiochemical properties by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma optical emission spectrometer (ICP-OES), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), mechanical and dielectric properties. The biological properties like hemocompatibility, antibacterial efficacy, in vitro bioactivity and the cell proliferation of the samples were determined. XRD pattern of the samples were of single phase hydroxyapatite. As the content of Fe(3+) increased, the crystallite size as well as crystallinity decreased along with a morphological change from spherulites to rods. The dielectric constants and Vickers hardness were enhanced on Fe(3+) doping. The VSM studies revealed that the saturation magnetization (M(s)) and retentivity (M(r)) were found to increase for Fe-nHAp. nHAp impregnated with an antibiotic as a new system for drug delivery in the treatment of chronic osteomyelitis was also attempted. The in vitro drug release with an antibiotic amoxicillin and anticancer drug 5-fluorouracil showed sustained release for the lowest concentration of Fe(3+), while with an increase in the content; there was a rapid release of the drug. The hemolytic assay of Fe(3+) doped samples revealed high blood compatibility (<5% hemolysis). The antibacterial activities of the antibiotic impregnated materials were tested against a culture of E. coli, S. epidermidis and S. aureus by agar diffusion test. The in vitro bioactivity test using simulated body fluid (SBF) showed better bone bonding ability by the formation of an apatite layer on the doped samples. The growth of the apatite layer on the samples surface has been confirmed by EDS analysis. The proliferative potential of MG63 cells by MTT assay confirmed the noncytotoxicity of the samples.