Size‐Evolving Protein Drug Nanoparticles: A Promising Non‐Invasive Strategy for Retinal Neovascularization by Overcoming Multiple Ocular Barriers

ABSTRACT Intravitreal injection (IVT) of anti‐vascular endothelial growth factor (VEGF) protein drugs is the gold‐standard treatment for retinal vascular diseases, which affect over 100 million people globally. However, this invasive approach is associated with significant risks, including infection, optic nerve damage, etc. As a non‐invasive alternative, eye drops provide a more patient‐friendly delivery option, but the delivery of protein drugs to the retina is hindered by both dynamic and static biological barriers, as well as the high molecular weight and hydrophilic nature of the proteins. In this study, we introduce a peptide (CG ₂ R ₉ )‐protein (bevacizumab, Beva)‐zinc ions (Zn ²⁺ ) co‐assembly strategy to develop progressively smaller nanoparticles, (CG ₂ R ₉ &Beva)@Zn. We examine the factors influencing particle formation, size evolution, encapsulation efficiency, loading capacity, and protein biological activity. Our findings show that (CG ₂ R ₉ &Beva)@Zn nanoparticles significantly enhance ocular surface retention time (dynamic barrier) and effectively cross multiple ocular static barriers as their size decreases, facilitating efficient protein drug delivery to the retina. In an oxygen‐induced retinal neovascularization model, these nanoparticles demonstrate appreciable therapeutic efficacy, without any observed biosafety concerns in 30 days of administration. This work presents a novel, non‐invasive strategy for protein drug delivery, offering potential for the treatment of retinal diseases.