Femtosecond-laser-assisted spatial cell adhesion to microstructured surface geometry

This article discusses the adhesion of C2C12 mouse myoblast cells to a microstructured polydimethylsiloxane (PDMS) surface patterned using femtosecond laser pulses. The wettability of the PDMS surface can be controlled by changing the writing-pulse energy; a hydrophilic surface is produced by low pulse energy, whereas high pulse energies lead to a superhydrophobic surface. The surface topography also varies with pulse energy. Images acquired with scanning electron microscopy show clear lines at low pulse energy, whereas at high energies, the lines are completely deformed by the presence of micro- and nano-structures. Thus, selective cell growth in the modified regions is affected by the energy of the laser pulses used for surface modification. In addition, the surface geometry (e.g., lines vs grids) of the modified regions affects the shape and alignment of C2C12 cells. Thus, we investigate the degree of cell alignment to modified lines fabricated with the same pulse energy and writing speed but with different inter-line spacings. The degree of alignment is quantified by the average value of a second-order Legendre polynomial. The results reveal that the degree of alignment of C2C12 cells to the surface lines decreases with the increase in spacing between lines.