Correlation of the adhesive properties of cells to N-iso-propylacrylamide/N-tert-butylacrylamide copolymer surfaces with changes in the surface structure using contact angle measurements, molecular simulations and Raman spectroscopy

A series of copolymers of N-isopropylacrylamide (NIPAM) and the more hydrophobic comonomer N-tert-butylacrylamide (NTBAM), with increasing NTBAM content (i.e. increasing hydrophobicity) were prepared. The adhesion of human endothelial cells on polymer films prepared from copolymers of NIPAM:NTBAM wa...

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Bibliographic Details
Published inChemistry of materials Vol. 17; p. 3889
Main Authors Lynch, I, Blute, IA, Zhmud, B, MacArtain, P, Tosetto, M, Allen, LT
Format Journal Article
LanguageEnglish
Published 2005
Subjects
cell adhesion
contact angle
hydrophobicity
N-isopropylacrylamide
N-tert-butylacrylamide
protein binding
Raman
surface energy
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Summary:A series of copolymers of N-isopropylacrylamide (NIPAM) and the more hydrophobic comonomer N-tert-butylacrylamide (NTBAM), with increasing NTBAM content (i.e. increasing hydrophobicity) were prepared. The adhesion of human endothelial cells on polymer films prepared from copolymers of NIPAM:NTBAM was observed to increase with increasing polymer hydrophobicity. However, in the absence of serum, cell adhesion to the different surfaces was statistically indistinguishable. Thus, it appears that the copolymer films differentially support cell adhesion due to selective adsorption of proteins from the physiological environment (the serum). Using contact angle measurements, molecular simulations and Raman spectroscopy to characterize the different surfaces, we show evidence that the different behavior of the films of increasing hydrophobicity is actually due to the different chemical properties of the surfaces with increasing content of NTBAM in the copolymers. As the NTBAM content is increased, the number of NH residues at the surface decreases, due to the additional steric hindrance of the bulkier NTBAM group, which results in decreased hydrogen bonding and thus decreased adsorption of proteins such as albumin. However, in some cases, the adsorption is driven by hydrophobic interactions, and proteins such as fibronectin were found to adsorb more to the films with a higher content of NTBAM. There appears, thus, to be a direct correlation between surface composition and protein binding and the subsequent cell adhesion.
ISSN:1520-5002
0897-4756