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L. Zheng, D. Myung, A. Bakri, J. Noolandi, J. Cochran, C. Frank, C. Ta; Biological Activity of Collagen Type I to Surfaced-Modified Hydrogels. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1866. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
This study examined the capacity of a surface-modified poly(ethylene glycol)/poly(acrylic acid) (PEG/PAA) hydrogel, designed to serve as a artificial cornea, to sustain biologically active collagen type I, which promotes surface corneal epithelialization.
PEG/PAA hydrogel surfaces were modified with varying densities of collagen type I through a photoreactive, bifunctional azide-active-ester linker. The bioactivity of the collagen tethered to the hydrogels was quantified using a conformation-specific antibody in an enzyme-linked immunosorbent assay (ELISA). The absorbances were compared to a standard curve of collagen adsorbed at varying concentrations to MaxiSorp polystyrene. Heat-denatured collagen was adsorbed to MaxiSorp polystyrene as a negative control.
Reactivity to bioactive collagen type I increased as a function of collagen reacted to the surface. A comparable trend was demonstrated by collagen adsorbed to the Maxisorp surfaces. Heat-denatured collagen did not produce a signal, indicating that the conformation-specific antibody could not detect inactive collagen.
One of the challenges in designing a polymer that supports surface covalent immobilization of proteins is surface-induced denaturation. These results, however, indicate that proteins remain in their native conformation when tethered to the PEG/PAA hydrogel surface. Therefore, this material can be used to tether proteins, such as collagen type I, to enhance epithelial cell growth and adhesion.
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