Synthesis and application of magnetic nanoparticles (MNPs) in drug delivery to the retina

Introduction The development of an innovative drug delivery system to target, after topical administration, the retina with bioactive agents against retinal pathologies is a major challenge. Currently, the sole approach to target these tissues is through intravitreous injection, but this is not free from problematics such as severe side effects and rapid clearance of small molecules from the vitreous. Purpose We aim to synthesize, develop and formulate a new magnetic nanoparticle‐mediated delivery technology that shall allow achieving needle‐free, anesthesia‐free delivery of active drugs to the retina after topical administration assisted by magnetic targeting. Methods MNPs have been synthesized, physico‐chemically characterized and loaded with small organic drugs (valproic acid/Guanabenz). The MNPs biocompatibility have been studied in vitro on retinal pigmented epithelium and photoreceptor cell lines and in vivo after topical administration. The MNPs have been applied on mice under the influence of an external magnetic field to guide them towards the retina. The in vivo histological and functional assays have been monitored to determine the biological effect of the treatment. Results The iron oxide‐based MNPs have spherical shape, a hydrodynamic size less than 150nm and they were not affected by the drug‐loading process. HPLC measurements demonstrate the high loading capacity of the MNPs and reproducibility of the method. Cell proliferation assays showed that MNPs are fully biocompatible. Conclusions MNPs combined with magnetic targeting is a promising technology for the delivery of bioactive agents to the retina after topical, needle‐free administration.