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D. Luensmann, M. L. Heynen, L. W. Jones; The Use of Confocal Microscopy to Investigate Albumin Penetration Into pHEMA-Based and Silicone Hydrogel Contact Lens Materials. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5377.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the penetration of albumin into five different contact lens materials over time, using confocal microscopy.
Conventional pHEMA-based (omafilcon A; Group II, etafilcon A; Group IV) and silicone hydrogel materials (balafilcon A; Group III, lotrafilcon B; Group I, senofilcon A; Group I) were examined. Bovine Serum Albumin (BSA) was labeled with 5-(4,6-Dichloro-s-triazin-2-ylamino) fluorescein hydrochloride (DTAF) and the lenses were incubated in vitro in this protein solution (0.5 mg/ml) at 37 degrees. After 1, 7 and 14 days lenses were removed, rinsed with phosphate buffered saline (PBS) and a central 4mm section was cut from the lens and placed on a microscopic slice. A confocal microscope (Zeiss LSM 510 META) identified the location of the fluorescently-labeled albumin by using 1µm depth scans through the lens.
All five contact lens materials had different albumin absorption profiles. For the silicone hydrogel materials, albumin absorption and penetration was significant after 1 day for balafilcon A and senofilcon A (p<0.001), while for the lotrafilcon B only a weak signal was observed even after 14 days (p>0.05). Of the conventional lens materials, omafilcon A absorbed significantly more albumin over time than etafilcon A (p<0.05). Lotrafilcon B had the lowest albumin uptake on the lens surface and inside the matrix at all time points, compared to the other four materials (p<0.001).
Using confocal microscopy to observe albumin absorption and penetration showed significant differences between contact lens materials. This technique shows much promise in the study of the interaction of proteins with hydrogel biomaterials.
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