Patterned and switchable surfaces for biomaterial applications

Chapter 1 - Introductionthe LCST, adhered to the PNIPAAm regions resulting in the formation of aheterotypic cell pattern. This approach has the advantage that cell detachment is notrequired. These methods are in principle adaptable to different cell types;theoretically any patterned co-culture of two cell types could be realised.Extending the above approach, Edahiro et al., [104] developed a photoresponsive,switchable surface for cell attachment. The surface was composed of PNIPAAm witha photoresponsive chromophore that underwent isomerisation upon exposure to UV,and reversed upon exposure to light in the visible spectrum. A Chinese hamsterovary cell line (CHO-K1) was shown to have preferential attachment to theisomerised chromophore once exposed to UV, although the mechanism for this wasnot understood. This surface was patterned by irradiation of UV through aphotomask to produce regions that cells preferentially attached to. Use of PNIPAAmenabled the bulk regeneration of the surface by reducing the temperature belowPNIPAAm’s LCST, causing the cells to detach.1-36