Surface modification of model hydrogel contact lenses with hyaluronic acid via thiol-ene “click” chemistry for enhancing surface characteristics

Abstract

Discontinuation of contact lens wear as a result of ocular dryness and discomfort is extremely common; as many as 26% of contact lens wearers discontinue use within the first year. While patients are generally satisfied with conventional hydrogel lenses, improving on-eye comfort continues to remain a goal. Surface modification with a biomimetic, ocular friendly hydrophilic layer of a wetting agent is hypothesized to improve the interfacial interactions of the contact lens with the ocular surface. In this work, the synthesis and characterization of poly(2-hydroxyethyl methacrylate) surfaces grafted with a hydrophilic layer of hyaluronic acid are described. The immobilization reaction involved the covalent attachment of thiolated hyaluronic acid (20 kDa) on acrylated poly(2-hydroxyethyl methacrylate) via nucleophile-initiated Michael addition thiol-ene "click" chemistry. The surface chemistry of the modified surfaces was analyzed by Fourier transform infrared spectroscopy-attenuated total reflectance and X-ray photoelectron spectroscopy. The appearance of N (1s) and S (2p) peaks on the low resolution X-ray photoelectron spectroscopy spectra confirmed successful immobilization of hyaluronic acid. Grafting hyaluronic acid to the poly(2-hydroxyethyl methacrylate) surfaces decreased the contact angle, the dehydration rate, and the amount of nonspecific sorption of lysozyme and albumin in comparison to pristine hydrogel materials, suggesting the development of more wettable surfaces with improved water-retentive and antifouling properties, while maintaining optical transparency (>92%). In vitro testing also showed excellent viability of human corneal epithelial cells with the hyaluronic acid-grafted poly(2-hydroxyethyl methacrylate) surfaces. Hence, surface modification with hyaluronic acid via thiol-ene "click" chemistry could be useful in improving contact lens surface properties, potentially alleviating symptoms of contact lens related dryness and discomfort during wear.

Contact Lens Materials: A Materials Science Perspective

“…On the other hand, the 169 kDa HA was responsible for the lowest amount of protein deposition. Korogiannaki et al covalently bonded HA to the surface of HEMA by using a nucleophilic Michael-addition thiol-ene “click” chemical reaction [165]. These lenses retained an optical transparency level of >92%, and decreased the water contact angle and rate of lens dehydration.…”

Tuning Physical Crosslinks in Hybrid Hydrogels for Network Structure Analysis and Mechanical Reinforcement

“…Hydrogels consisting of 3D polymer backbone networks and large amounts of water [1,2], are used in many industries for their soft and wet features [3], such as sewage treatment, contact lenses [4], sensing [5,6], separation [7,8], drug delivery [9,10], and tissue engineering [11]. Most applications require robust hydrogels that can withstand mechanical loads over time [12].…”

Thiolated Hyaluronic Acid as Versatile Mucoadhesive Polymer: From the Chemistry Behind to Product Developments—What Are the Capabilities?

“…The application of contact lenses generally contributes to the exacerbation of the symptoms associated to the dry eye syndrome. Reflexing to this, Korogiannaki et al [32] formulated a thiolated HA hydrogel for the improvement of surface properties of contact lens, which improve a higher lens compatibility with the ocular environment. Apart from dry eye syndrome, improving the treatment of retinal attachment represents high industrial interest, as the current vitreous substitute such as silicone oils are not biodegradable and have to be removed via a second surgery.…”