fig8

Figure 8. Schematic design and performance validation of a microfluidic contact lens sensor for point-of-care detection of GSH in tears under OS conditions. (A) Fabrication process: (i) UV laser ablation of poly(HEMA-co-EG)/PVP contact lenses to form fluidic channels, (ii) assembly with two non-ablated lenses, and (iii) formation of a sandwiched microfluidic contact lens sensor with inlet, outlet, and sensing area. The embedded CCAE fluorophore undergoes a Michael addition reaction with GSH, shifting fluorescence from orange (565 nm) to light blue (488 nm), and reversibly recovers upon H₂O₂ exposure, simulating OS; (B) Protocol for GSH monitoring: (i) the patient wears the lens for tear collection and detection, (ii) a bespoke smartphone-based readout device captures and processes sensor signals, (iii) data is displayed through a user-friendly app, and (iv) the lens is regenerated in buffer for reuse; (C-K) Evaluation of sensor performance: (C) Optimization of emission ratio (I₅₆₅/I₄₈₈) based on GSH:H₂O₂ volume ratio and H₂O₂ concentration, (D) calibration of emission response over a wide range of H₂O₂ concentrations, (E) simulation of dynamic OS and medication effects, (F) emission spectra with increasing GSH concentrations, (G) calibration curves for mild and severe oxidative conditions, (H) stability across physiological tear pH (6.0-8.0), (I) temperature-dependent sensor behavior, (J) selectivity against common tear analytes including UA, ions, glucose, and proteins under mild and severe OS conditions, and (K) demonstration of the reversible sensing ability across 15 detection cycles. Reprinted with permission from^[123], Copyright© 2025 Shi et al. Published by Elsevier B.V. GSH: Glutathione; OS: oxidative stress; poly(HEMA-co-EG)/PVP: poly((hydroxyethyl)methacrylate-co-ethylene glycol)/polyvinylpyrrolidone; CCAE: 2-cyano-3-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)-N,N-dimethylacrylamide; UA: uric acid.