Micro-nano scale motion control of light-driven morphing pillars for biointerfacing.

Morphic biomaterials have been widely utilized as cell instructive platforms to regulate biological functions of cells and tissues. Here, light can be exploited to tune the mechanical response of these materials (e.g., azobenzene-based polymers) to reshape and induce dimensionality changes (e.g., from 2D to 3D geometries). In fact, 3D systems better replicate the cell-tissue environment and its continuous conformational changes. In this work, we present a 3D pillar-based platform capable of undergoing reshaping and dislocation. These properties can be precisely controlled at the micro-nano scale through characteristic light irradiation parameters such as intensity and exposure time. In this work, light-driven deformation resulting in elongation, polarization, and substructure generation (i.e., nanobump-like structures) was achieved using low-intensity (5%) light exposure. Furthermore, deformation in sliding and rotation was obtained with high laser intensity (20-100%, % of 10 mW input), based on which, a photo-induced deformation model was proposed for azobenzene-based polymers. Additionally, the biocompatibility of the azopolymer-based pillars was proven as well as their potential to locally reshape and induce real-time cell response.