(55e) Electrospinning of Novel Tricalcium/Poly(Lactide-Co-Glycolide) Nanocomposites for Repair of Bone Defects

Electrospinning is a most suitable tool for the preparation of open structured, highly accessible networks of polymer fibers. The process is widely used to synthesize materials for application in reinforcement, filtration, medical prostheses engineering, and tissue engineering. Recently electrospun scaffolds has recently also been proposed for the regeneration of bone or cartilage defects. The application of electrospun fibers in vivo requires biocompatibility of the materials and at best guarantee biodegradability. Presently the research in the field of electrospun biomaterials focuses on polymers such as poly(lactic acid), poly(glycolic acid) and their copolymers. The continuous development of flame spray synthesis during the last few years resulted in the extension of accessible materials from oxides to metal salt nanoparticles, specifically calcium phosphate materials [1, 2]. Presently, calcium phosphates find extensive application in medical applications as bone fillers or for coating of medical implants. They are considered to have oseoconductive properties allowing for guided bone formation and chemical bonding to bone. Most recently, a study on the incorporation of tricalcium phosphate nanoparticles in biodegradable polymer films strongly promoted the degradation of the latter [3]. This effect was primarily attributed to pore forming through dissolution of the nanoparticles located at the surface of the composite which resulted in an enhanced polymer surface accessible for hydrolysis. In the present work, we would like to combine the benefits of the electrospinning method with the advantages of flame-made, bioactive, amorphous tricalcium phosphate (ATCP) nanoparticles. Scaffolds of particle loading ranging from 0 to 40 wt% were prepared by a conventional electrospinning method. The novel materials may be applied for the repair of bony defects and offer an easy-applicable tool in orthopedics.

Transmission electron micrograph of flame-made (A) amorphous tricalcium phosphate shows agglomerated, spherical nanoparticles with high specific surface area. Scanning electron microscopy of electrospun ATCP/PLGA nanocomposite reveals an open, regular structured network of fibers (B). The high magnification image (C) of a single fiber shows small, bright features which may arise from incorporated nanoparticles exposed to the surface.

[1] Stark WJ, Pratsinis SE, Maciejewski M, Loher S, Baiker A; Falme synthesis of metal salt nanoparticles, in particular calcium and phosphate comprising nanoparticles. patent WO2005/087660 A1. 2005 03/15/2004.

[2] Loher S, Stark WJ, Maciejewski M, Baiker A, Pratsinis SE, Reichardt D, et al., 2005, Fluoro-apatite and calcium phosphate nanoparticles by flame synthesis. Chemistry of Materials; 17:36-42.

[3] Loher S, Reboul V, Brunner TJ, Simonet M, Dora C, Neuenschwander P, et al., 2006, Improved degradation and bioactivity of amorphous aerosol derived tricalcium phosphate nanoparticles in poly(lactide-co-glycolide). Nanotechnology; 17:2054-2061.