Axisymmetric adhesion test to examine the interfacial interactions between biologically-modified networks and models of the extracellular matrix

The adhesion between artificial extracellular matrixes (ECMs), or scaffolds, and native tissue is an often overlooked component of the tissue engineering design process. Therefore, we developed an axisymmetric adhesion test method to examine the interfacial interactions between hydrogel scaffolds and a model of the articular cartilage ECM. Semi-interpenetrating polymer networks (semi-IPNs), consisting of poly-(N-isopropylacrylamide-co-acrylic acid) [P(NIPAAm-co-AAc)] hydrogels and physically entangled linear P(AAc) chains grafted with peptides that bind to hyaluronic acid (HA), were synthesized, and the adhesion between the P(NIPAAm-co-AAc)-based semi-IPNs and hemispherical glass lenses (plain or HA-grafted) was examined as a function of temperature, contact time, and semi-IPN type. The adhesion between the semi-IPNs and the lenses significantly increased with increasing contact time and significantly decreased with increasing temperature, independent of the P(NIPAAm-co-AAc)-based matrix type. Furthermore, when using a 5-min contact time at 22 °C, the peptide-modified P(NIPAAm-co-AAc)-based semi-IPNs demonstrated significantly greater adhesion to the HA-grafted lenses, compared to that exhibited between nonfunctionalized P(NIPAAm-co-AAc)-based semi-IPNs and HA-grafted lenses. The method developed is useful for examining the interfacial interactions between biologically modified polymer scaffolds and models of the native ECM and may aid in improving the integration between synthetic polymers and native tissues.