Study on surface of polydimethylsiloxane irradiated by laser with assistance of pre-strain and its regulation on cell alignment.

In this work, wave-pattern with particles on polydimethylsiloxane (PDMS) surface was induced by laser with the assistant of pre-strain. By analyzing the laser treated surface with an energy dispersive spectrometer, Raman spectra, scanning electron microscope and atomic force microscope, it is found that no chemical modification occurs, but the young's modulus of the treated surface shifts dramatically to 43.4 MPa. This Young's modulus change, together with the existence of pre-train, causes buckling phenomenon that forms the wave-pattern with particles when the pre-strain is unloaded. As the laser fluence varies from 7.9 mJ cm−2 to 14.3 mJ cm−2, the wave-pattern with particles only appeared with the pre-strain at 30% and 45%. The laser fluence contributes positively to the length and the amplitude of the wave-pattern, while increased elongation on PDMS results in shorter wavelengths but higher amplitudes. HELA cells were seeded on the treated surface to verify the effect of the wave-pattern with particles on cell alignment. The experimental results show that the wave-pattern with particles improves the cell attachment. It was found that 96.2% of cells align at 0°–15° when the gap between two neighboring treated zones is shorter than the cell length. However, the cell alignment changes its direction to 75°–90° when the treated zone is narrowed and the gap is enlarged. This paper provides a simple method for forming a wave-pattern with particles and utilizes the pattern to regulate cell behavior. [ABSTRACT FROM AUTHOR]