Surface-attached PDMAA-GRGDSP hybrid polymer monolayers that promote the adhesion of living cells

Peptide-polymer hybrid molecules are being introduced, where one part of the molecule (i.e., the peptide) promotes the adhesion of living cells, whereas the other part of the molecule (i.e., the synthetic polymer) is known to prevent cell adhesion. The hybrid copolymer, poly(dimethylacrylamide) (PDMAA)-glycine-arginine-glycine-aspartic acid-serine-proline (GRGDSP) was synthesized by first preparing an initiator-modified peptide and in a second step growing the PDMAA block directly off the peptide through atom transfer radical polymerization (ATRP). The PDMAA block length can be varied by adjusting appropriate polymerization conditions, thereby changing progressively the amount of the cell-repelling part of the molecule. The hybrid copolymer was further used to prepare surface-attached peptide-polymer monolayers at planar solid glass substrates through a photochemical immobilization process. By blending of the hybrid copolymer with PDMAA homopolymer (i.e., without peptide), the apparent peptide film concentration can be varied in a very simple manner. The adhesion of human skin fibroblast cells in serum-free medium was investigated as a function of the amount of peptide-polymer in the solution used for film preparation. Cells do not adhere to a pure PDMAA monolayer; however, already 0.02 wt % of peptide in the film is enough to induce cell adhesion, and 0.1 wt % promotes stress-fiber formation within adherent cells. Using lithographical means, chemically micropatterned peptide-polymer films were prepared that allow for a spatial control of the adhesion of living cells and thus they constitute a simple platform for the design of live-cell biochips.