Optically actuated microtools for cell manipulation

Micro-robots provide the possibility to multiply the optical force, so that the mechanical force is sufficient for cell force analysis. Embryonal wild-type zebrafish cells in a cell-specific environment were probed by light-driven micro-robots featuring different functionalizations. It has been shown that a force exerting tool can transport and deform zebrafish cells in a controlled manner. Cells reacted on puncture by the formation of pathological blebs related to a rupture of the actin cortex and the subsequent protrusion of the lipid bilayer that forms the cell membrane. In another experiment the tooltip of the micro-robot adhered to the lipid bilayer and controlled membrane tethers could be pulled from the cell, thereby observably affecting the elastic properties of the entire cell. Rotational kinematic joints and force sensing mechanisms have been developed to increase the versatility of the micro-robots. Additionally, the performance of fluorescent polymer structures were tested by introducing laser dyes into the prepolymer and adapting the processing protocol, therefore enabling background free visualization.

 

Figure 3: Left: SEM image of the developed pushing tool showing the quality of writing resolution. Middle: Cell deformation by pushing the cell with the tool against the wall. The cell is deformed by the tool. Right: Tether formation from zebrafish plasma membrane. Two adherent zebrafish cells pinched by a micro-robot form a tether between the membrane and the substrate, after further punctuation the tether attaches to the tooltip and is elongated.