Cell adhesion and proliferation on hydrophilic dendritically modified surfaces

Dendritically modified, or "dendronized" surfaces are generated by modification of a substrate with perfectly branched polymers, known as dendrimers. Here, such dendronized surfaces were prepared by initial chemisorption of poly(ethylene glycol)-mono-thiol (HS-PEG(650)-OH) onto gold-coated silicon wafers, followed by divergent synthesis of aliphatic polyester dendrons, generation 1-4, starting from the terminal PEG OH- group. The adhesion and proliferation of human corneal epithelial cells (HCEC) and mouse 3T3 fibroblasts (M-3T3) as model cells on these hydroxyl-terminated dendronized surfaces were investigated. In addition, the effect of covalently attaching PEG mono-methyl ether (PEG-OMe) chains (M(n)=2000 Da) to the peripheral hydroxyl groups of G1- and G2-dendronized surfaces on adhesion and proliferation of the same cell lines was studied. Little or no HCEC adhesion was noted on gold surfaces modified with PEG mono-thiol (HO-PEG-SH) in serum-free medium. These cells showed a greater affinity for the dendronized surfaces compared to the control Au surfaces at early incubation stages (1 day). At longer incubation times, HCEC proliferation increased exponentially on the dendronized surfaces. However, when G1- and G2-dendronized surfaces were modified with PEG-OMe chains, adhesion of both HCEC and M-3T3 cells was significantly reduced. Cell studies with M-3T3 fibroblasts, carried out in serum-containing medium, showed that cell attachment was diminished for the PEG-grafted Au surfaces compared to the control Au and G1-G4 dendronized surfaces.