Abstract
Purpose :
Responsive surfaces can be created by modifying materials with switchable molecules to optimize the properties at the surface for modulating cell behaviour. Azobenzene can reversibly switch from the trans- to the cis-conformation with 365 nm light. Photo-responsive surfaces can reversibly influence protein adsorption and cellular interactions. Evidence suggests the design and material of intraocular lenses (IOLs) influence lens epithelial cell (LECs) behaviour to propagate complications post-lens replacement surgeries. This research develops photo-switchable surfaces for IOLs using azobenzene to modulate LEC behaviour.
Methods :
Circular glass coverslips were coated in 35% methacrylic acid (MAA) with isodecyl acrylate (IDA), which has shown to improve healing responses (Wells and Sefton, 2014). These coatings were grafted with 4-(phenylazo)benzoic acid with an amine-terminated triblock copolymer as a spacer using carbodiimide chemistry. Azobenzene changes using UV (ultraviolet) light exposures, followed by observing 325 nm peaks to identify the trans-conformation with UV-VIS (ultraviolet-visible) light spectroscopy. Human LECs (B3-LECs) were incubated on modified coatings and with or without UV light to measure their viability using the alamarBlue and LIVE/DEAD assays.
Results :
MAAcoIDA coatings were grafted with 7.4 ± 2.2 nmol/cm2 of azobenzene. UV-VIS spectroscopy confirmed that grafted azobenzene on the surface retained the ability to photoisomerize shown through reductions in absorbance at 325 nm (Fig. 1). Current work shows a red-shifted absorbance maximum as trans-azobenzene complexes with β-cyclodextrin and still undergo photoisomerization with the cis-conformation unable to bind with β-cyclodextrin.
B3-LECs incubated with unmodified MAAcoIDA and azo-functionalized coatings had no changes in viability over 48 hours (p > 0.05) (Fig. 2). There were no changes in viability when B3-LECs were exposed to low-power (2.5 mW/cm2, 45 minutes) (p > 0.05) and high-power UV light (18 mW/cm2, 45 minutes[SK1] ) (p > 0.05). Cells grown with azobenzene-grafted copolymers under UV light are expected to have changes in behaviour.
Conclusions :
These studies modified regenerative copolymers with azobenzene, which can reversibly bind with β-cyclodextrin. The resulting coatings show low toxicity and are expected to modulate LEC behaviour upon UV exposures with intensities demonstrated not to effect LEC viability.
This is a 2021 ARVO Annual Meeting abstract.