Swelling Induced Detachment of Chondrocytes Using RGD-Modified Poly(N-isopropylacrylamide) Hydrogel Beads

Thermally sensitive poly(N-isopropylacrylamide, NIPAAm) hydrogel beads conjugated with a cell adhesive motif, GRGDY, were prepared and utilized as cell culture substrate for chondrocytes. They were produced to be uniform in size and distribution by using calcium alginate as a temporal mold. The RGD moieties were introduced, in a spatially selective manner, to the surface of the beads by conjugating GRGDY under the precollapsed state at a higher temperature above the lower critical solution temperature (LCST). These RGD-conjugated polyNIPAAm beads demonstrated a reversible swelling and deswelling behavior around the LCST, which enabled the chondrocytes attached on the surface of collapsed beads at 37 °C to readily detach when the temperature was shifted below 37 °C. The cell detachment percentage was largely affected by the temperature-dependent reswelling extent of the collapsed RGD-modified beads.