ROS-pH Dual-Responsive Polydopamine Nanoparticles for Targeted Fasudil Delivery Ameliorate Multiple Pathologies in Diabetic Retinopathy

Background: The multifaceted pathogenesis of diabetic retinopathy (DR) involves numerous pathways, among which oxidative stress and Rho-associated kinase (ROCK) signaling are critically implicated. The failure of current anti-VEGF monotherapies to address these key pathological processes limits their efficacy. While the ROCK Inhibitor Fasudil is a promising candidate, its clinical translation for DR is hindered by poor ocular retention and lack of target specificity.

Methods: We engineered a Reactive Oxygen Species (ROS)- and pH-dual responsive polydopamine nanoplatform (Fasudil@PDA) to deliver Fasudil while concurrently scavenging oxidative stressors.

Results: The Fasudil@PDA nanoparticles achieved a high drug loading capacity of ~28%. The release kinetics were specifically engineered to be responsive to the DR microenvironment. Under high ROS conditions in vitro, the platform demonstrated a sustained and efficient release profile, achieving a cumulative release of 87.3% over 56 days - demonstrating remarkable longevity. Separately, the pH-responsive drug release capability was also confirmed under acidic conditions. The platform effectively neutralized multiple ROS species in vitro and significantly restored endothelial barrier integrity by inhibiting the ROCK/MLC pathway. In a laser-induced choroidal neovascularization model, a single injection suppressed pathological angiogenesis by 45%. In diabetic mice, the same treatment markedly reduced vascular leakage, attenuated neuroinflammation, and restored retinal function, with b-wave amplitudes recovering to near-normal levels.

Conclusion: This study establishes a multi-faceted nanotherapeutic strategy that synergizes sustained, long-acting ROCK inhibition with innate antioxidant activity. Designed to be activated by the pathological cues of DR, including acidic pH and ROS, our approach precisely targets multiple pathological pathways, offering a promising and translatable paradigm for overcoming the limitations of current monotherapies.