Replication of a Tissue Microenvironment by Thermal Scanning Probe Lithography

Abstract

Thermal scanning probe lithography (t-SPL) is a nanofabrication technique in which an immobilized thermolabile resist, such as polyphthalaldehyde (PPA), is locally vaporized by a heated atomic force microscope tip. Compared with other nanofabrication techniques, such as soft lithography and nanoimprinting lithography, t-SPL is more efficient and convenient as it does not involve time-consuming mask productions or complicated etching procedures, making it a promising candidate technique for the fast prototyping of nanoscale topographies for biological studies. Here, we established the direct use of PPA-coated surfaces as a cell culture substrate. We showed that PPA is biocompatible and that the deposition of allylamine by plasma polymerization on a silicon wafer before PPA coating can stabilize the immobilization of PPA in aqueous solutions. When seeded on PPA-coated surfaces, human mesenchymal stem cells (MSC) adhered, spread, and proliferated in a manner indistinguishable from cells cultured on glass surfaces. This allowed us to subsequently use t-SPL to generate nanotopographies for cell culture experiments. As a proof of concept, we analyzed the surface topography of bovine tendon sections, previously shown to induce morphogenesis and differentiation of MSC, by means of atomic force microscopy, and then "wrote" topographical data on PPA by means of t-SPL. The resulting substrate, matching the native tissue topography on the nanoscale, was directly used for MSC culture. The t-SPL substrate induced similar changes in cell morphology and focal adhesion formation in the MSC compared to native tendon sections, suggesting that t-SPL can rapidly generate cell culture substrates with complex and spatially accurate topographical signals. This technique may greatly accelerate the prototyping of models for the study of cell−matrix interactions.

Transferrin-targeted porous silicon nanoparticles reduce glioblastoma cell migration across tight extracellular space

“…Immunostaining and transfection. Immunofluorescence conducted was based on the protocol recently described by Tang et al 72 . The cells were cultured in the migration chips for 24 h, followed by treatment and migration for 8 h then fixed in freshly prepared 4% paraformaldehyde (PFA) at room temperature for 15 min.…”

Thermal scanning probe lithography—a review

“…Human mesenchymal stem cells adhered, spread and proliferated on these PPA nanostructures. This experiment demonstrates the capabilities of t-SPL and PPA for the study of cell-matrix interactions, including rapid prototyping of biocompatible scaffolds 59 .…”

“…The example of molecular glass resists shows that a few additional requirements need to be considered for a t-SPL resist to be suited for general nanofabrication: 59 or be used to guide and trap nanoparticles 56,57,58 . After assembly, the PPA resist can be removed by heating 55 .…”

Emerging Scanning Probe–Based Setups for Advanced Nanoelectronic Research

“…According to the tip‐sample interaction used to define the lithographic pattern (i.e., mechanical, thermal, diffusive and electrical), SPL approaches can be classified in: i) Mechanical SPL (m‐SPL) : this technique creates patterns on the surface of samples by removing the materials selectively. The process of patterns' formation mainly relies on the strong contact force between the tip and the sample . ii) Thermal SPL (t‐SPL) : this technique uses a heating probe to alter the properties of the sample locally .…”