Femtosecond laser micro/nano patterning ofbiological materials

Femtosecond laser micro/nano patterning ofbiological materials


Author(s): Costas P. Grigoropoulos, Hojeong Jeon, Univ. of California, Berkeley(United States); Hirofumi Hidai, Univ. of California, Berkeley (Japan); DavidJ. Hwang, Univ. of California, Berkeley (United States)
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This talk aims at presenting recent work at the Laser Thermal Laboratory on themicroscopic and nanoscale laser modification of biological materials usingultrafast laser pulses. We have devised a new method for fabricating highaspect ratio patterns of varying height by using two-photon polymerizationprocess in order to study contact guidance and directed growth of biologicalcells. Studies using NIH-3T3 and MDCK cells indicate that cell morphology onfiber scaffolds is influenced by the pattern of actin microfilament bundles.Cells experienced different strength of contact guidance depending on the ridgeheight. Cell morphology and motility was investigated on micronscale anisotropiccross patterns and parallel line patterns having different aspect ratios. Asignificant effect on cell alignment and directionality of migration wasobserved. Cell morphology and motility were influenced by the aspect ratio ofthe cross pattern, the grid size, and the ridge height. Cell contractility wasexamined microscopically in order to measure contractile forces generated byindividual cells on self-standing fiber scaffolds. We have also introduced amethod for generating user-defined nanopatterns of cell adhesion ligands byablating an ultrathin protein adsorption resistant poly(ethylene glycol) brushlayer using focused femtosecond laser pulses to expose an underlying adhesivesubstrate. The ablated regions were modified with peptides designed to engagewith specific receptors. We were able to generate nanometer scale regions ofcell adhesive peptides, while independently controlling feature size andspacing, hence allowing direct specification of the number and area of focaladhesion patterns. We have also conducted experiments to determine the effectof laser-induced nanoscale laser topography on cell adhesion.

Breast coil for multiplanar MRI/optical spectroscopy in vivo