Publications

Research with soft materials, that is, polymeric gels, colloidal suspensions, liquid crystals, and most biomaterials often involves the need for microfabrication of confinement channels, cells, and lab-on-a-chip devices. Photolithography techniques are often chosen, as they offer the combination of versatility, precision, and quick delivery demanded by researchers. Beyond fabrication, stimulus-responsive systems, such as photosensitivity biomaterials, are the object of broad study within a very interdisciplinary community. Here, we show that a standard laboratory microscope can be quickly and economically transformed into a powerful maskless photofabrication/photoexcitation station using off-the-shelf DMD development modules and simple optomechanical components allowing real time observation of the fabrication process.

JTD Keywords: Dmd, Microscopy, Photolithography, Soft matter

Gradients of signaling pathways within the intestinal stem cell (ISC) niche are instrumental for cellular compartmentalization and tissue function, yet how are they sensed by the epithelium is still not fully understood. Here a new in vitro model of the small intestine based on primary epithelial cells (i), apically accessible (ii), with native tissue mechanical properties and controlled mesh size (iii), 3D villus-like architecture (iv), and precisely controlled biomolecular gradients of the ISC niche (v) is presented. Biochemical gradients are formed through hydrogel-based scaffolds by free diffusion from a source to a sink chamber. To confirm the establishment of spatiotemporally controlled gradients, light-sheet fluorescence microscopy and in-silico modeling are employed. The ISC niche biochemical gradients coming from the stroma and applied along the villus axis lead to the in vivo-like compartmentalization of the proliferative and differentiated cells, while changing the composition and concentration of the biochemical factors affects the cellular organization along the villus axis. This novel 3D in vitro intestinal model derived from organoids recapitulates both the villus-like architecture and the gradients of ISC biochemical factors, thus opening the possibility to study in vitro the nature of such gradients and the resulting cellular response.© 2022 The Authors. Advanced Healthcare Materials published by Wiley-VCH GmbH.

JTD Keywords: 3d architectures, biomolecular gradients, colon, crypt, engineering organoids, hydrogels, identification, in silico modeling, intestinal stem cell niches, light sheet fluorescence microscopy, niche, permeability, photolithography, regeneration, villus, wnt, 3d architectures, Biomolecular gradients, Engineering organoids, In silico modeling, Intestinal stem cell niches, Light sheet fluorescence microscopy, Photolithography, Stem-cell

Cells sense their environment through the cell membrane receptors. Interaction with extracellular ligands induces receptor clustering at the nanoscale, assembly of the signaling complexes in the cytosol and activation of downstream signaling pathways, regulating cell response. Nanoclusters of receptors can be further organized hierarchically in the cell membrane at the meso- and micro-levels to exert different biological functions. To study and guide cell response, cell culture substrates have been engineered with features that can interact with the cells at different scales, eliciting controlled cell responses. In particular, nanoscale features of 1-100 nm in size allow direct interaction between the material and single cell receptors and their nanoclusters. Since the first "contact guidance" experiments on parallel microstructures, many other studies followed with increasing feature resolution and biological complexity. Here we present an overview of the advances in the field summarizing the biological scenario, substrate fabrication techniques and applications, highlighting the most recent developments.Copyright © 2022 Casanellas, Samitier and Lagunas.

JTD Keywords: cell response, density, differentiation, lithography, micro, nanofabrication, nanopatterning, nanopatterns, nanoscale, nanotopography, organization, photolithography, Cell response, Nanofabrication, Nanopatterning, Nanotopography, Plasma-membrane, Receptor nanoclustering

Rapid and inexpensive development of electrochemical sensors with good exploitation potential may be produced using a polymer as a substrate material. However, fabrication of polymer-based sensors is challenging. Using photolithography and etching of gold-coated poly(ethylene-2,6-naphthalate) (PEN), we have succeeded in fabricating disk-shaped and interdigitated microelectrodes (uEs). The electrodes have an excellent adhesion to the polymer and are encapsulated using a novel room-temperature process, applicable for low-cost, high-throughput fabrication. The PEN surface has been characterized in respect of wettability, surface energy and surface roughness. Finally, the electrodes give stable and reproducible electrochemical impedance spectroscopy and cyclic voltammetry responses, using the redox couple ferrocyanide and ruthenium hexamine. The results demonstrate the robustness and functionality of the polymer-based sensor platform with minimum feature sizes of 6 um.

JTD Keywords: Poly(ethylene naphthalate), Photolithography, Microelectrodes, Interdigitated electrodes, Electrochemical characterization, Electrochemical sensor