PEG-grafted dopamine methacrylate-functionalized hydroxyl-terminated PDMS-based silicone hydrogel contact lenses for sustained ocular drug delivery.

Ocular drug delivery systems characterized by extended retention time and high bioavailability are urgently required to overcome the limitations of conventional eye drops. In this study, a novel drug-loaded silicone hydrogel contact lens (SHCL) was developed utilizing hydroxyl-terminated polydimethylsiloxane (PDMS-OH) as the silicone matrix, poly(ethylene glycol)-grafted methacryloyldopamine (PEG-MAD) as a functional monomer, and sodium acetyl hyaluronate (SAH) as a surface coating. PEG-MAD was synthesized via a lipase-catalyzed reaction between carboxyl-terminated PEG (PEG-COOH) and methacryloyldopamine (MAD). This synthetic approach not only prevented the oxidation and yellowing of MAD during high-temperature polymerization but also introduced additional hydrogen bonds, thereby enhancing the mechanical properties and drug-loading capacity of the hydrogel. The SHCL was fabricated through free radical polymerization, followed by drug loading (using levofloxacin as a model drug) and SAH coating. The optimized SHCL exhibited a water content of 59.5%, high optical transmittance (91% in the visible light region), and no ocular irritation (as evaluated by the CAM test, with an irritation score of 0). Compared to control groups lacking PEG-MAD or using 3-(Methacryloyloxy)propyltris(trimethylsiloxy)silane (TRIS) as the silicone matrix, the developed SHCL demonstrated a higher drug-loading capacity (3.28 μg/mg dry gel) and sustained drug release over 96 h, along with a significant reduction in human serum albumin adsorption. These findings indicate that the PEG-MAD-functionalized, PDMS-OH-based SHCL holds considerable promise for clinical applications in ocular drug delivery.