Therapeutics and carriers: the dual role of proteins in nanoparticles for ocular delivery.

Blindness and visual impairment affect millions of people worldwide and have a very important impact on patients quality of life. Proteins and peptides represent nowadays an important therapeutic tool for the treatment of ocular diseases but, despite their potential, have significant limitations, as the administration of protein-based pharmaceuticals represents a real challenge. Moreover, administration of ocular medications is difficult due to the peculiar structure of this organ and the presence of numerous barriers protecting the eye inner structure. Nanoencapsulation of peptides and proteins presents a number of advantages for their ocular delivery since it can protect the drug from metabolic activity, control and sustain the release and increase drug bioavailability after topical or intravitreal administration. In fact, nanoparticulate formulations are contributing to overcome ocular barriers, such as the corneal or the blood-retinal barrier, improve the residence time in the eye, increase local drug level, reduce the drug dosage and showing improved performance when compared to conventional formulations. Besides, proteins have also been proposed for the preparation of nanocarriers intended for ophthalmic administration, since they are highly biocompatible, biodegradable and easily modified to link surface ligands. The present review focuses the attention on the use of proteins in ocular drug delivery nanotechnology: their dual role as both therapeutics and carriers has been critically evaluated and discussed.