Liquid Crystalline Microenvironments For Tissue Engineering

Abstract

In this present work, gels with liquid crystalline (LC) phases were studied based on cellulose and collagen. The cellulose was further incorporated in a polymer matrix (polyvinyl alcohol) and in a biocompatible material (glycerol), in order to produce gels with LC phases. The LC phases and other properties of the gels were further investigated in order to determine relationships between structure/properties. Preliminary cellular studies were done to unravel the influence of the LC phase in cell proliferation and the changes in the LC phase due to the presence of the cells. Nanocrystalline cellulose (NCC) with different aspect ratio, were obtained by acid hydrolysis with sulfuric acid at different reaction times. Gelation of collagen type I was not achieved. The NCC/PVA gels did not presented LC patterns. NCC/glycerol gels with NCC concentration higher than 7% (w/w) showed, through polarized optical microscopy, a fingerprint texture characteristic of the chiral nematic ordering of the NCC. The pitch of LC phase, increase with the NCC length and no significant variations were observed in gels with higher NCC content. For cell culture studies the 7% (w/w) NCC concentration was selected and the pH of the gels was increased by incubation with culture medium and an increase in the pitch size was noticed. A negative zeta potential of the gels was observed even after pH increase. No chemically modifications were observed by ATR-FTIR after increasing the gels’ pH. Preliminary rheological studies gave a good indication of the materials’ viscoelastic properties and its thixotropic behaviour. Exploratory cellular tests showed low cell adhesion and cytotoxic tests led to conclude that 48 hours of incubation with culture medium is needed before any cellular studies. This study shown that the NCC/glycerol gel is a promising material to use in tissue engineering applications.