Enhanced effects of lithocholic acid incorporation into liquid-crystalline biopolymer poly(coumaric acid) on structural ordering and cell adhesion

A novel thermotropic liquid-crystalline biocopolymer, poly{trans-4-hydroxycinnamic acid (4HCA: trans-coumaric acid)-co-lithocholic acid (LCA)}, was synthesized by a thermal polycondensation of 4HCA and LCA. When the LCA composition of P(4HCA-co-LCA) was 0, 5, 7, 23, 27, and 45 mol%, the copolymers showed a nematic liquid-crystalline phase. The melting point of the copolymers was 120–250 °C depending on the LCA composition, and showed a maximum at 7 mol%. Wide angle X-ray diffraction (WAXD) analyses showed a typical diffraction pattern of a hexagonal arrangement for 0, 7, 23, and 27 mol% LCA composition, which were cooled from a nematic melt. The other polymers showed no distinct diffraction. In particular, the copolymer of 7 mol% LCA composition showed four distinct diffractions corresponding to spacings with a reciprocal ratio of 1, √3, 2, and √7, indicating the highest structural ordering of all copolymers prepared here. The results of the cell adhesion and static contact angle tests suggest that the 7 mol% LCA composition copolymer had the highest hydrophobicity and cell adhesion ability, which was easily controlled by altering in feed. We conclude that the structural ordering may have a significant correlation with cell adhesion activity.