부산대학교 도서관

Mammalian cells are highly sensitive to variations in cues provided by their surroundings. Directed cell migration is key to many physiological processes and there is a need for tissue engineering materials and structures to encourage optimised cell response. This thesis describes the creation of different types of gradients in collagen films and investigates their physicochemical properties and resultant cell behaviour. Crosslinking gradients were formed by gradual immersion of collagen films into different crosslinking solutions. The use of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride with N-hydroxysuccinimide (EDC/NHS) influenced both the mechanical and chemical properties, while crosslinking using genipin altered mechanical behaviour without changing surface chemistry. By adjusting the rate of immersion and solution concentration, gradient shape could be controlled. The effect of crosslinking chemistry was evaluated on uniformly treated films, using tensile testing, atomic force microscopy, and (2,4,6-Trinitrobenzene-1-sulfonic acid). An increase in stiffness from 3.5 to 26.6 MPa was obtained by varying the concentration of EDC/NHS solutions and from 3.5 to 23.9 MPa in the case of genipin. Cell response to mechanical and chemical variations based on crosslinking and peptide dendrimer (IKVAV) attachment was tested using human dermal fibroblasts (HDFs), fibrosarcoma cells (HT1080s) and rat Schwann cells (RSCs). HDFs showed an unfavourable response to high EDC/NHS crosslinking levels, but increased proliferation with increasing genipin crosslinking. The presence of IKVAV dendrimers enhanced RSC adhesion and proliferation. On gradient films, the variation in chemistry and stiffness created by EDC/NHS presented competing effects. The response of HT1080s was dependent on the type and profile of crosslinking gradient. On IKVAV gradients, migration of RSCs towards higher concentrations was promoted, whereas HDF movement was discouraged. This body of work demonstrates, for the first time, the use of this method in forming property gradients in collagen, which can provide cues to achieve directional cell response.