In the time of an aging population, regenerative therapies, such as tissue engineering, gain in importance. In-situ tissue engineering is such a way for replacement of body tissue and can be facilitated by an implant equipped with drug delivery systems allowing spatially and temporally controlled release of growth factors.
To prepare such implants we modified electrospun polycaprolactone fiber mats with a strongly adherent coating, obtained by self-polymerization of dopamine. Beside increasing the wettability the coating provides a charged surface, which enables a further functionalization with chitosan-based and protein loaded nanoparticles by a dipping procedure. This procedure allows to generate fiber mats with three different regions as can be shown using differently fluorescence-labeled nanoparticles and confocal laser scanning microscopy. Furthermore, the release of biologically active growth factors BMP-2 and TGF-β from the modified and functionalized fiber mats was established. Thus, the methodology is suited to prepare implants, which can release growth factors in a spatially and temporally graded way and can be used for in-situ tissue engineering.
 S.R. Nielsen, Phys. Chem. Chem. Phys. 15 (2013) 17029-17037.