Charge and topography patterned lithium niobate provides physical cues to fluidically isolated cortical axons

Abstract

In vitro devices that combine chemotactic and physical cues are needed for understanding how cells integrate different stimuli. We explored the suitability of lithium niobate (LiNbO3), a transparent ferroelectric material that can be patterned with electrical charge domains and micro/nanotopography, as a neural substrate. On flat LiNbO3 z-surfaces with periodically alternating charge domains, cortical axons are partially aligned with domain boundaries. On submicron-deep etched trenches, neurites are aligned with the edges of the topographical features. Finally, we bonded a bicompartmental microfluidic chip to LiNbO3 surfaces patterned by etching, to create isolated axon microenvironments with predefined topographical cues. LiNbO3 is shown to be an emerging neuron culture substrate with tunable electrical and topographical properties that can be integrated with microfluidic devices, suitable for studying axon growth and guidance mechanisms under combined topographical/chemical stimuli.

Quantitative assessment of neural outgrowth using spatial light interference microscopy

“…In the future, we plan to utilize pyroelectrification techniques for micro-object patterning as well as LiNbO 3 and lithium niobate as a neuron substrate to quantify and measure biomaterial-induced changes in cell behavior. [38][39][40] These platform technologies can be combined with SLIM for probing neuronal behaviors, such as neurite outgrowth and branching, at the subcellular level in topographically and chemically controlled environments. Using SLIM to quantitatively measure neurite outgrowth dynamics in a broader context has the potential to help elucidate the complex environmental and intrinsic signals that regulate and modulate neuritic outgrowth, pruning, and arborization-the substrate for neuronal function.…”

Biological applications of ferroelectric materials

“…83,[85][86][87][88][89] Therefore, intracellular [Ca 2+ ] changes seem to us a very important signaling element, that may have a crucial role in the observed cell responses to excited ferroelectrics. [28][29][30][31]35,59 As Ca 2+ has also been involved in the regulation of other critical responses such as cell proliferation, 85 contractibility, 86 or differentiation/dedifferentiation 88 to name a few, this signaling ion could have a relevant role in other reported biological responses to ferroelectrics: osteoblastic differentiation 60,64 or enhanced proliferation. [61][62][63][64][65][66] It deserves mentioning that, although Ca 2+ signaling features the largest number of studies in the field of electric biomodulation, there are some works shedding light upon other relevant voltage-gated channels, like Na + channels 86 or K + channels, 85 to explain cellular responses to electric fields.…”

Bulk and Surface Electronic Properties of Inorganic Materials: Tools to Guide Cellular Behavior

“…Recent work regarding charged substrates has been targeted toward the study of lithium niobate (LiNbO 3 ), a ferroelectric material that has a spontaneous polarization, P S = 0.71 C m −2 along its polar axis. Prior studies have shown that nonfunctionalized LiNbO 3 surfaces are biocompatible with osteoblasts, mesenchymal stem cells, and neurotypic cells . The polarity of LiNbO 3 has been shown to drastically affect osteoblast cell behavior .…”

“…In a representative study by Marchesano et al, fibroblast cells (NIH 3T3) showed a quantifiable dependence on polarity—the cytoskeletal spreading was visualized during microscopy studies and showed a significant enhancement on the negative face of the inorganic LiNbO 3. Etched and patterned LiNbO 3 has also been utilized to align neurites in vitro based on surface charge and topography . Recently there have been several novel techniques developed to investigate the polarization of LiNbO 3 on cell behavior using holographic total‐internal‐reflection microscopy (HoloTIRM) and spatial light‐interference microscopy .…”