A nanocomposite contact lens for the delivery of hydrophilic protein drugs

To improve the efficiency of topical ocular drug administration, we developed a nanocomposite contact lens to deliver hydrophilic protein drugs over a prolonged period of time. Here, an in situ route was used to encapsulate the hydrophilic protein drug bovine serum albumin (BSA) within gelatin nanoparticles (NPs), 180 +/- 20 nm in diameter, which were then grafted onto the lens material, a copolymer of 2-hydroxyethyl methacrylate and 2-aminoethyl methacrylate p(HEMA-co-AEMA), through photopolymerization. The thickness of the nanocomposite lens was controlled at 150 mm. The release kinetics of BSA from plain p(HEMA-co-AEMA), gelatin NPs, and gelatin NP-grafted p(HEMA-co-AEMA) in phosphate buffer saline (PBS) at pH 7.4 were studied. The release profile of BSA encapsulated within gelatin NPs could be monitored for 7 days, three times longer than that of BSA soaked in p(HEMA-co-AEMA). Our findings indicate that use of the nanocomposite contact lens, i.e. BSA-loaded gelatin NPs incorporated into p(HEMA-co-AMEA), can prolong the release profile of BSA to 12 days. The swelling behavior and interior strain of p(HEMA-co-AEMA) with and without grafted NPs (1000 : 1 w/w) were further investigated. The nanocomposite lens shows higher swelling behavior than the plain p(HEMA-co-AEMA) lens does. The addition of gelatin NPs to hydrogels leads to a relatively uniform interior strain with lower stiffness. Thus, the prolonged release might be due to a combination of effects. Internal diffusion of the nanocomposite lens materials may significantly contribute to the prolonged release of protein drugs. Furthermore, the nanocomposite lens materials had no cytotoxicity. This new biocompatible nanocomposite might be further developed as an alternative tool for continuous topical ocular drug delivery over a prolonged period of time.