Polyelectrolyte multilayers and capsules: S-layer functionalization for improving stability and biocompatibility

Recent advances in medicine and biotechnology have brought about the need to develop nano-engineered delivery systems that can encapsulate a wide variety of therapeutics and that could allow their targeted delivery and sustained release. Nanostructured polyelectrolyte multilayers (NPMs) and capsules (NPCs), fabricated by electrostatic layer-by-layer (LbL) technique have been proposed for the functionalization of biomaterials and as delivery systems. This paper focuses on the degradation and biocompatibility characterization of NMPs and NPCs functionalized with bacterial self-assembled proteins (S-Layers). S-layers have been proposed as an efficient strategy for the functionalization of NPMs and NPCs. In present work, S-layers were recrystallized on mica and imaged by atomic force microscopy. The LbL assembly and the stability of cationic poly (allylamine hydrochloride) and anionic sodium poly (styrene sulfonate) multilayers functionalized with a terminal S-Layer were investigated by means of quartz crystal microbalance. In order to evaluate the impact of S-layer functionalization on the degradation of NPCs, S-Layer functionalized NPCs were characterized in vitro in terms of cell morphology and viability. The results revealed the role of S-layers in decreasing component release from NPMs and thus in increasing release time from NPCs.