Cell adhesion control of microtool using thermo-responsive polymer and laser heating

We proposed novel optically-driven microtool which can control cell adhesion on its surface by laser heating. The microtool is made of polystyrene microbead coated with thermo-responsive hydrogel, Poly (N-isopropylacrylamide) (PNIPAAm). Target cells adhere to the surface of the microtool at the temperature higher than Lower Critical Solution Temperature (LCST) and do not adhere at the temperature lower than LCST. Thus, the microtool can transport target cell by controlling adhesion of the cell on its surface by changing the temperature. The microtool is heated by irradiation of infrared laser used for optical tweezers and the temperature is controlled by regulating laser power and environmental temperature. First, relationship between temperature and cell adhesion rate of PNIPAAm was evaluated. Second, we experimentally measured the controllability of the temperature by temperature-sensitive fluorescent reagent. We confirmed that the temperature of the tool was increased 7.5 °C by irradiating the laser. Finally, we demonstrated adhesion and transportation of the single Synechocystis SPP. 6803 by irradiating laser with 65 mW.