Improvement and characterization of the adhesion of electrospun PLDLA nanofibers on PLDLA-based 3D object substrates...

Intensive research has demonstrated the clear biological potential of electrospun nanofibers for tissue regeneration and repair. However, nanofibers alone have limited mechanical properties. In this study we took poly(L-lactide-co-D-lactide) (PLDLA)-based 3D objects, one existing medical device (interference screws) and one medical device model (discs) as examples to form composites through coating their surface with electrospun PLDLA nanofibers. We specifically investigated the effects of electrospinning parameters on the improvement of adhesion of the electrospun nanofibers to the PLDLA-based substrates. To reveal the adhesion mechanisms, a novel peel test protocol was developed for the characterization of the adhesion and delamination phenomenon of the nanofibers deposited to substrates. The effect of incubation of the composites under physiological conditions on the adhesion of the nanofibers has also been studied. It was revealed that reduction of the working distance to 10 cm resulted in deposition of residual solvent during electrospinning of nanofibers onto the substrate, causing fiber-fiber bonding. Delamination of this coating occurred between the whole nanofiber layer and substrate, at low stress. Fibers deposited at 15 cm working distance were of smaller diameter and no residual solvent was observed during deposition. Delamination occurred between nanofiber layers, which peeled off under greater stress. This study represents a novel method for the alteration of nanofiber adhesion to substrates, and quantification of the change in the adhesion state, which has potential applications to develop better medical devices for orthopedic tissue repair and regeneration.