A single molecule carrier for ocular posterior segment diseases

Eye drops are envisaged as the most promising non-invasive formulation for the treatment of the ocular posterior segment diseases, while it is hindered by a series of complex ocular barriers, both static and dynamic in nature. In this context, we propose a single molecule nanomedicine based on host-guest chemistry to achieve highly efficient drug delivery targeted to ocular posterior segment. Sulfonated azocalix[4]arene (SAC4A) serves as the single molecule carrier, owing the multiple features of small size (24.0 Å in length, 21.2 Å in width, 14.8 Å in height with a Van der Waals volume of 930 Å³), negative charge, hydrophilicity, loading universality and hypoxia-triggered release. As a proof-of-concept, an eye drop formed by the complexation of SAC4A with sunitinib (SUN) is prepared to treat wet age-related macular degeneration (wAMD). SAC4A successfully transports SUN to the ocular posterior segment (the amount of SUN reaching the retinal-choroid tissue in the SUN@SAC4A group was 2.47 times larger than that in the SUN group at 30 min), significantly enhancing its anti-choroidal neoangiogenesis effect of SUN to wAMD, which played a key role in the treatment. We believe that the single molecule nanomedicine paradigm is highly amenable for treating various ocular posterior segment diseases in the future.