Additive electrospraying: a new route to process electrospun scaffolds for controlled molecular release

Electrohydrodynamics -- i.e. electrospinning, electrospraying and atomization -- are gaining a growing interest in drug delivery applications, because of a large number of advantages including improved therapeutic index, localized delivery/targeting and controlled drugs toxicity level. In the past, microstructured platforms fabricated by the assembly of electrospun fi bers have demonstrated to exhibit interesting features as bioactive carriers including extended surface area and high molecular permeability because of fully interconnected pore architecture, thus making the opportunity to incorporate a wide range of actives/drugs for different use. In these systems, molecular release occurs via various molec- ular transport pathways namely diffusion, desorption and scaffold degradation which may be tuned through a careful control of fi ber morphology and composition. However, several shortcomings still concern the possibility to incorporate bioactive species, not exposing molecules to fast and/or uncontrolled denaturation, thus preserving biochemical and biological fi ber functionalities. In this context, additive electro spraying (AES) -- i.e. integration of electrosprayed nano- particles into electrospun fi ber network -- is emerging as interesting route to control " separately " release and functional properties of the scaffolds in order to support cell activities by independent cues, during the tissue formation. Here, we describe the current advances on the use of electrospraying and/or electrospinning until more innovative integrated AES approaches to design molecularly loaded platforms able to spatially and timely release active molecules for different use in tissue engineering and molecular targeting.