Paper Title
Magnetic Elastomers with Variable Elasticity for Cell Culture Substrate

Abstract
The Controlling the growth speed of stem cells or suppressing cancer cells is extremely important and valuable for the therapy of diseases. Some biologists and medical scientists have reported that the elastic modulus of substrate affects the growth speed or differentiation of cells. Magnetic soft materials have attracted much attention as the substrate since the elastic modulus of magnetic soft materials can be changed by magnetic fields without changing other experimental conditions such as temperature, solvent composition, pH etc. Actually, a novel device was reported that the effect of the elastic modulus of substrate on the cell growth was investigated(1). However, it was reported recently that the contact angle for magnetic elastomers changes by magnetic fields due to spike structure(2). We have developed so far magnetic soft materials, elastomers and gels, with wide range modulation of elastic modulus by a weak magnetic fields(3), and also found that the particle dispersibility affects significantly not only magneto rheological effect but also contact angle(4,5). The purpose of this study is to obtain magnetic elastomers exhibiting large changes in elastic modulus by magnetic fields without changing the surface property. We synthesized magnetic elastomers consisting of poly(propylene glycol), plasticizer (dioctyl phthalate, DOP), and carbonyl iron (7.0 m) particles. The contact angle and the modulus change in local for the obtained elastomers were investigated.