Abstract
Purpose :
To develop a microfluidic chip for testing the release of ocular drugs from soft contact lenses using 3D printing.
Methods :
The microfluidic chips were designed using CAD software consisting of a top and bottom portion. The top portion is comprised of inlet, outlet, and channels for fluid flow. The lower portion contained a dome-shaped mount to mount a contact lens. The chips were printed using clear resin on a commercial stereolithography 3D printer. The printed chips were washed in isopropyl alcohol (IPA) for 30 minutes, air-dried and UV cured for 30 minutes. The top and bottom portions of the chip were fused by applying a thin layer of resin, followed by UV-curing for 10 minutes. In another design iteration, moulds for the chips were 3D printed and casted with polydimethylsiloxane (PDMS). The two halves of the PDMS chips were fused using double-sided adhesive tape. In a preliminary study, two commercial contact lenses, etafilcon A and senofilcon A, were soaked in 2 ml of red food dye for 2 hours. The release of the dye was measured using the PDMS chip with phosphate-buffered saline at a flow rate of 1.5 µL/min over 24 hours via absorbance at 520 nm. The dye extraction from both lenses was performed by incubating the dye-soaked lenses in 1:1 acetonitrile/water solution for 24 hours with gentle shaking.
Results :
Both the chip and moulds were printed in less than 5 hours, with a minimum resolution of 50 µm. The resulting resin and PDMS chips can also be sterilized by autoclaving. The release kinetics of the dye was linear throughout the 24 h period for both lens types under the current parameters. The total amount of dye released after 24 h was higher for etafilcon A (26.26 mg/lens) than senofilcon A (18.41 mg/lens), which corresponded to approximately 83.1% and 40.01% release, respectively. Both the lens types were still visibly red after 24 hours. The output of the microfluidic chip could be used as an input for subsequent analyses.
Conclusions :
This study showed a cost- and time-efficient approach to fabricate a microfluidic chip for evaluating drug release from contact lenses. Future work will examine the release profile of various ocular drugs from contact lenses using different flow conditions.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.