Application of β-1,3-glucan in production of ceramics-based elastic composite for bone repair
IntroductionHydroxyapatite (HAp), especially in a porous form, is appreciated as a bone filler due to its biocompatibility, bioactivity, osteoconductivity, minimal risk of appearance of allergic reactions, lack of carcinogenic properties and lack of sensitivity to sterilization processes [1][2][3]. There are numerous commercially available bone graft materials based on biologic and synthetic HAp, including ProOsteon ® (Interpore Cross International, USA), Endobon (BIOMET Orthopaedics, Switzerland), Cerapatite (Ceraver Osteal, France), Synatite (SBM, France) and others. HAp may serve not only as a bone filler but also as a carrier of active substances: antibiotics, chemiotherapeutics, growth factors, etc. [4][5][6][7][8][9]; it can also be used in composites, as a factor increasing their cytocompatibility, bioactivity, osteoconductivity, adhesion of coatings and compression modulus [10][11][12][13][14]. On the other hand, HAp application is often limited due to its relatively poor resorption and slow replacement by the host bone after implantation, substantially high Young modulus, and low fracture toughness [15,16], although these properties may be improved by addition of elasticity-increasing polymers. It is considered that polymer-ceramic composites reveal superior properties (at least in some aspects) over polymer and ceramic alone [17]. However, most polymers used for bone filler fabrication meet only some of the criteria for implantable materials.Bone replacing material such as ceramics or crushed bone offers an insufficient surgical handiness, especially when the orthopedic surgeon has to handle granules (in case of defects in maxillary bone) or scaffolds (rigid and non-adaptable to the implantation site). Some commercially available biomaterials contain the artificial or natural polymers serving as plasticizing agents and thus significantly reduce this inconvenience. Among them, EasyGraft TM (Degradable Solutions SA, Switzerland), Plexur M and P (Osteotech, USA) and Cerapatite-Collagen (Ceraver Osteal, France) can be listed. EasyGraft TM contains PLGA-coated β-TCP granules which hardens into a compact mass via partial and temporary PLGA dissolution by organic solvent; Plexur M and P are composed of cortical bone and resorbable artificial polymer; Cerapatite-Collagen, made from HAp granules and naturally-derived collagen fibers, becomes elastic after hydration with blood or saline. Bone or ceramic granules and powders may also be turned into a paste using collagen gels (e.g., Tecnoss ® Gel O; Tecnoss, Italy) or fibrin glue [18,19]. However, the natural polymeric compounds used in commercially available composites (collagen, fibrin glue) originate from animal sources; this can be considered as a limiting factor because of the increased risk of transmissible contamination (e.g. viruses) and undesirable immune responses. Thus, the necessity of careful purification of these animal polymers exacts the high price of fin...
