preservation of fgf-2 bioactivity using heparin-based nanoparticles, and their delivery from electrospun chitosan fibers

here we present a novel matrix-mimetic nanoassembly based on polysaccharides. chitosan electrospun fiber networks are decorated with heparin-containing polyelectrolyte complex nanoparticles (pcns) that present basic fibroblast growth factor (fgf-2), both stably adsorbed to the surfaces and released into solution. these fgf-2/pcn complexes can be released from the fibers with zero-order kinetics over a period of 30 days. further modification of fibers with a single bilayer of polyelectrolyte multilayer (pem) composed of n,n,n-trimethyl chitosan and heparin completely prevent release, and the fgf-2/pcn complexes are retained on the fibers for the duration of the release experiment (30 days). we also compare the mitogenic activity of these fgf-2/pcn complexes delivered in two different states: adsorbed to a surface and dissolved in solution. fgf-2/pcn complexes exhibit mitogenic activity with respect to ovine bone marrow-derived mesenchymal stem cells, even after being preconditioned by incubating for 27 days at 37 °c in solution. however, when the fgf-2/pcn complexes are adsorbed to chitosan and coated with pems, the mitogenic activity of the fgf-2 steadily decreases with increasing preconditioning time. this work demonstrates a new system for stabilizing and controlling the delivery of heparin-binding growth factors, using polysaccharide-based matrix-mimetic nanomaterials. this work also contributes to our understanding of the preferred mode of growth factor delivery from porous scaffolds.