(266f) Gold Nanoparticle Synthesis in Contact Lenses for Drug-Less Ocular Cystinosis Treatment

Background/motivation: Ocular cystinosis is an orphan disease characterized by the accumulation of cystine crystals in the stroma layers of the cornea. Currently, ocular cystinosis are commonly treated by installing cysteamine eye drops for cystine clearance. However, cysteamine is prone to oxidation at body temperature before diffusing through the cornea, which significantly limit its bioavailability. Here, we develop a novel contact lens with immobilized and stable gold nanoparticles, which can react with cystine molecules in the tear film. Therefore, instead of releasing drug to clear the cystine crystals inside the cornea, cystine molecules in the tear film diffused into the contact lens and attached to the surface of gold nanoparticles, which will reduce the cystine concentration in the tear film and lead to a dissolution of cystine in the cornea, eventually.

Methods: Surfactants might affect the binding of cystine to the gold. Therefore, to avoid the surfactant, gold nanoparticles are synthesized inside the preformed commercial contact lenses (Acuvue TruEye and Acuvue Moist contact lenses) by first loading the lenses with gold precursor followed by reduction to the gold atoms, which will then nucleate and grow to gold nanoparticles inside the contact lens. The gold loading is adjusted by either increase the concentration of gold precursor solution or repeating the manufacturing process. The gold nanoparticles are characterized by SEM, XRD, UV-Vis spectroscopy and the gold loading in the contact lens is determined by measuring the mass change of the dehydrate lenses. The mechanism of the synthesis is revealed by investigating the transport of the gold precursor and reducing agents. The amount of the reacted cystine is characterized by monitoring the concentration of cystine solution, after soaking the gold nanoparticle-loaded contact lenses in cystine solution.

Results: The gold loading in the contact lens increases linearly with the gold precursor concentration and the number of repeating manufacturing cycles. Results also show that stronger reducing agent leads to a lower gold loss during the synthesis, and the gold loading is higher in the Moist contact lens due to higher diffusivity in the lens. When repeating the manufacturing process, smaller gold nanoparticles of 10 nm (vs 100 nm for Moist) in size are generated inside the TruEye contact lens, which results in a higher cystine binding of around 47 microgram/lens in 5 hours (vs 33 microgram/lens in 2 hours for Moist) due to the higher surface area.

Conclusion: A method of gold nanoparticle contact lens manufacturing is reported, which is used for drugless ocular cystinosis treatment by binding significant amount cystine on the surface of gold nanoparticles inside the contact lens. Moist lens has its benefit for the rate of cystine removal, while TruEye lens has its advantage for cystine binding amount.