Lithography-free fabrication of reconfigurable substrate topography for contact guidance

Abstract

Mammalian cells detect and respond to topographical cues presented in natural and synthetic biomaterials both in vivo and in vitro. Micro- and nano-structures influence the adhesion, morphology, proliferation, migration, and differentiation of many phenotypes. Although the mechanisms that underpin cell-topography interactions remain elusive, synthetic substrates with well-defined micro- and nano-structures are important tools to elucidate the origin of these responses. Substrates with reconfigurable topography are desirable because programmable cues can be harmonized with dynamic cellular responses. Here we present a lithography-free fabrication technique that can reversibly present topographical cues using an actuation mechanism that minimizes the confounding effects of applied stimuli. This method utilizes strain-induced buckling instabilities in bi-layer substrate materials with rigid uniform silicon oxide membranes that are thermally deposited on elastomeric substrates. The resulting surfaces are capable of reversible of substrates between three distinct states: flat substrates (A = 1.53 ± 0.55 nm, Rms = 0.317 ± 0.048 nm); parallel wavy grating arrays (A|| = 483.6 ± 7.8 nm and λ|| = 4.78 ± 0.16 μm); perpendicular wavy grating arrays (A⊥ = 429.3 ± 5.8 nm; λ⊥ = 4.95 ± 0.36 μm). The cytoskeleton dynamics of 3T3 fibroblasts in response to these surfaces was measured using optical microscopy. Fibroblasts cultured on dynamic substrates that are switched from flat to topographic features (FLAT-WAVY) exhibit a robust and rapid change in gross morphology as measured by a reduction in circularity from 0.30 ± 0.13 to 0.15 ± 0.08 after 5 min. Conversely, dynamic substrate sequences of FLAT-WAVY-FLAT do not significantly alter the gross steady-state morphology. Taken together, substrates that present topographic structures reversibly can elucidate dynamic aspects of cell-topography interactions.

Control of cell growth on 3D‐printed cell culture platforms for tissue engineering

“…Ideally, engineered tissue scaffolds must provide a platform onto which cells can adhere, proliferate, and differentiate . However, the scaffolding not only influences these cellular processes but can also affect cell behaviors . As a result, exploring scaffolds are essential to understand the effects of different structures on cell growth and proliferation.…”

“…[8][9][10] However, the scaffolding not only influences these cellular processes but can also affect cell behaviors. [11][12][13][14] As a result, exploring scaffolds are essential to understand the effects of different structures on cell growth and proliferation. For example, aligned fibers and anisotropic scaffolds can emulate the environment of cells and guide cell growth (such as fibroblast).…”

“…For example, aligned fibers and anisotropic scaffolds can emulate the environment of cells and guide cell growth (such as fibroblast). 6,7,15 Many different techniques have been developed in the recent years to build cell culture platforms and scaffolds for tissue engineering, including selective laser sintering, 16 stereo lithography, 17 fused filament fabrication, 18 microfabrication, 11 phase separation, 19 electrospinning 20 and 3D printing. [21][22][23][24] Electro-hydrodynamic jet (E-jet) printing is a new high-resolution printing method whereby the geometric feature of the built scaffolds can be precisely controlled using a broad range of materials.…”

Mimicking physiological flow conditions to study alterations of bioactive glass surfaces in vitro

“…25 On a cellular level, surface structures in the low micrometre range can guide adhesion and differentiation. [26][27][28][29] Parallel groove-ridge structures can cause cell contact guidance of many cell types on different materials [30][31][32][33] with the groove depth becoming more important as the grooves become deeper. 26,30,31,34 In addition, it has been shown that human mesenchymal stem cells (hMSC) guided towards elongation tend to differentiate into osteoblasts, whereas rounded ones are more prone to differentiate towards adipogenic cells.…”

Nanoscale physicochemical properties of chain‐ and step‐growth polymerized PEG hydrogels affect cell‐material interactions

“…7,8 The effect of nanoscale matrix features on cell functions has been confirmed by multitudes of in vitro studies, which utilize a variety of tools to produce cell substrates containing nano-grooves, pores, and ridges with widths ranging between 100-500 nm and depths of 100-380 nm. [9][10][11][12][13] These features affect patterning of human gingival fibroblasts, 14 porcine periodontal ligament epithelial cells and osteoblasts, 15 modulate cell morphology and function, 16 and promote attachment and spreading of epithelial cells. 17 In addition to commonly utilized silicon and poly(styrene) substrates, thermoresponsive polymers have been utilized to spatially control fibroblast adhesion and temperature-responsive detachment.…”