Effect of poly(ethylene glycol) graft polymerization of poly(methyl methacrylate) on cell adhesion

Abstract

Purpose: To investigate the effect of surface modification of poly(methyl methacrylate) (PMMA) by poly(ethylene glycol) (PEG) grafting on cell adhesion. Setting: Department of Ophthalmology, Seoul National University Hospital, Seoul, Korea. Methods: The PMMA surface was oxidized with ozone, and PEG acrylate was then graft polymerized. To verify the PEG grafting on the surface, the oxygen content was measured by electron spectroscopy for chemical analysis. The contact angle was measured using the Wilhelmy plate method. The adhesion of keratocytes on modified PMMA was investigated in vitro. Cultured rabbit keratocytes (4 ×10⁵ cells/mL) were layered on each PMMA disk, cultured in a carbon dioxide incubator for 24 hours, harvested by trypsinization, and counted. A commercially available intraocular lens was modified as described and then inserted in the anterior chamber of a white rabbit. The cell adherence pattern on the modified IOL was examined by scanning electron microscopy. Results: The PEG-grafted PMMA revealed a higher oxygen content and lower dynamic receding contact angles than the untreated PMMA. The mean number of adhered cells was 72.5 ± 22 × 10⁴/mL for untreated PMMA. After PEG grafting of 1 hour and ozone oxidation of 2 hours, the adherent cell counts significantly decreased to 6.5 ± 1.7 × 10⁴/mL and 7.6 ± 1.6 × 10⁴/mL, respectively (P = .002). Scanning electron microscopy showed small round cells sparsely scattered on the modified PMMA in contrast to the untreated PMMA. Conclusion: Surface modification of PMMA using PEG grafting reduced cell adhesion. This may decrease the incidence of retroprosthetic membrane formation after keratoprosthesis surgery.