Multifunctional poly(ethylene glycol) semi‐interpenetrating polymer networks as highly selective adhesive substrates for bioadhesive peptide grafting

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Abstract
Novel artificial extracellular matrices were synthesized in the form of semi-interpenetrating polymer networks containing copolymers of poly(ethylene glycol) and acrylic acid (PEG–co-AA) grafted with synthetic bioadhesive peptides onto exposed carboxylic acid moieties. These substrates were very resistant to cell adhesion, but when they were grafted with adhesive peptides they were highly biospecific in their ability to support cell adhesion. Extensive preadsorption of adhesive proteins or peptides did not render these materials cell adhesive; yet covalent grafting of adhesive peptides did render these materials highly cell adhesive even in the absence of serum proteins. Polymer networks containing immobilized PEG–co-AA were grafted with peptides at densities of 475 ± 40 pmol/cm2. Polymer networks containing immobilized PEG-co-AA N-terminally grafted with GRGDS supported cell adhesion efficiencies of 42 ± 4% 4 h after seeding and became confluent after 12 h. These cells displayed cell spreading and cytoskeletal grafted with inactive control peptides (GRDGS, GRGES, or no peptide) supported cell adhesion efficiencies of 0 ± 0%, even when challenged with high seeding densities (to 100,000 cell/cm2) over 14 days. These polymer networks are suitable substrates to investigate in vitro cell-surface interactions in the presence of serum proteins without nonspecific protein adsorption adhesion signals other than those immobilized for study.