Reversible Holographic Patterns on Azopolymers for Guiding Cell Adhesion and Orientation

Abstract

Topography of material surfaces is known to influence cell behavior at different levels: from adhesion up to differentiation. Different micro- and nanopatterning techniques have been employed to create patterned surfaces to investigate various aspects of cell behavior, most notably cellular mechanotransduction. Nevertheless, conventional techniques, once implemented on a specific substrate, fail in allowing dynamic changes of the topographic features. Here we investigated the response of NIH-3T3 cells to reversible topographic signals encoded on light-responsive azopolymer films. Switchable patterns were fabricated by means of a well-established holographic setup. Surface relief gratings were realized with Lloyd's mirror system and erased with circularly polarized or incoherent light. Cell cytoskeleton organization and focal adhesion assembly proved to be very sensitive to the underlying topographic signal. Thereafter, pattern reversibility was tested in air and wet environment by using temperature or light as a trigger. Additionally, pattern modification was dynamically performed on substrates with living cells. This study paves the way toward an in situ and real-time investigation of the material-cytoskeleton crosstalk caused by the intrinsic properties of azopolymers.

Effects of substrate patterning on cellular spheroid growth and dynamics measured by gradient light interference microscopy (GLIM)

“…The three‐dimensional (3D) dynamics of biological specimens, such as organoids, can be diverse, complex and challenging to assess precisely . Previous work on the mechanical environment's influence on cell behavior involves the use of microbumps , topographic signals and the polarization of ferroelectric materials . Although several studies have reported on the effects of cell cultures , no technique, to our knowledge, has been used to simultaneously tackle quantitative growth and mass transport.…”

Photoreversible Soft Azo Dye Materials: Toward Optical Control of Bio‐Interfaces

“…Therefore, in physiological conditions the photoinscribed topographies were unstable and could revert to their initial condition in a “shape‐memory” fashion . Rianna et al also used surface relief patterns on a glassy azo polymer for culturing NIH‐3T3 murine fibroblasts, attempting to exploit the erasure of azo polymer photopatterning using light . 1D‐ and 2D‐gratings with different periods were inscribed on the azo material ( Figure a) and an incoherent light source (a 15 mW mercury lamp) filtered in the blue region provided erasure, forming ordered microbumps at the surface, forcing cells to align along this new topographical cue.…”

Driving Cells with Light‐Controlled Topographies

“…[25][26][27][28][29] When dealing with 2D light-responsive substrates, topographies can be instructed by a direct laser writing exposure of azopolymeric films previously spun on planar glass substrates. [31][32][33] As an alternative, projection masks [34] or laser interference lithography can be used. [31][32][33] As an alternative, projection masks [34] or laser interference lithography can be used.…”