Reversible and dynamic micro-topographic pattern on azo-polymers substrates to investigate cell behavior in real-time

The cellular response to the external environment is a central aspect in tissue engineering and biomedical science. The topographical signals play an important role in cell-material interactions; in particular, in natural... [ view full abstract ]

The cellular response to the external environment is a central aspect in tissue engineering and biomedical science. The topographical signals play an important role in cell-material interactions; in particular, in natural tissues there is a dynamical remodeling of topographical features that influence many cells processes, such as migration, orientation and differentiation.
The conventional static culturing systems do not allow to understand how cell respond to spatio-temporal changes of signals. In order to overcome the limits of these static systems and to develop versatile platforms, great interest has recently arisen using stimuli-responsive materials as dynamic support to investigate cell response.
In this work azo-polymers have been used to realize dynamic light-switchable support. Thanks to the fact that azobenzene molecules undergo a reversible trans-cis-trans isomerization process, when illuminated with a coherent and linear light at a proper wavelength, formation of topographic features is archived with potential use in nanopatterning. In fact, illumination causes a unique and remarkable surface mass-transport on micrometer and sub-micrometer length scale.
Here, we report a method to fabricate and characterize many different topographic patterns using a confocal microscope set-up to guide and evaluate cell behavior. This set-up enables a precise spatial and temporal control on the inscription process, exposing dynamic topographical cues to live cells in real-time. This innovative method allows erasing the embossed pattern and eventually rewriting another pattern in the same spot, thus switching on or off topographical signal in live cell condition.
This technique may pave the way to an in depth investigation of complex processes involved in cell-topography interactions in a dynamic and biomimetic way, owing to the versatility of confocal set-up and the unique properties of the azobenzene surfaces.