Laser Direct Writing of Dual-Scale 3D Structures for Cell Repelling at High Cellular Density

Abstract

The fabrication of complex, reproducible, and accurate micro-and nanostructured interfaces that impede the interaction between material’s surface and different cell types represents an important objective in the development of medical devices. This can be achieved by topographical means such as dual-scale structures, mainly represented by microstructures with surface nanopatterning. Fabrication via laser irradiation of materials seems promising. However, laser-assisted fabrication of dual-scale structures, i.e., ripples relies on stochastic processes deriving from laser–matter interaction, limiting the control over the structures’ topography. In this paper, we report on laser fabrication of cell-repellent dual-scale 3D structures with fully reproducible and high spatial accuracy topographies. Structures were designed as micrometric “mushrooms” decorated with fingerprint-like nanometric features with heights and periodicities close to those of the calamistrum, i.e., 200–300 nm. They were fabricated by Laser Direct Writing via Two-Photon Polymerization of IP-Dip photoresist. Design and laser writing parameters were optimized for conferring cell-repellent properties to the structures, even for high cellular densities in the culture medium. The structures were most efficient in repelling the cells when the fingerprint-like features had periodicities and heights of @200 nm, fairly close to the repellent surfaces of the calamistrum. Laser power was the most important parameter for the optimization protocol.

A Review on Stimuli-Actuated 3D Micro/Nanostructures for Tissue Engineering and the Potential of Laser-Direct Writing via Two-Photon Polymerization for Structure Fabrication

“…A critical condition is that the 3D micro/nanostructures accurately mimic the composition and architecture of the natural tissues [22,[89][90][91][92][93]. Cell adhesion to specific surfaces is influenced by both surface chemistry and surface topography [94]. Among the important properties of the 3D micro/nanostructures are morphology, chemistry and cell adhesion properties.…”

“…Among the important properties of the 3D micro/nanostructures are morphology, chemistry and cell adhesion properties. There are also several other properties that can be conferred to the structures, such as electrical conductivity or magnetic properties [89][90][91][92][93][94]. To date, 3D micro/nanostructures have been stimulated through exposure to mechanical, chemical, electric and magnetic stimuli ( [23] and references therein).…”

“…Until recently, complex multi-scale 3D structures were designed using top-down, bottom-up and hybrid approaches. The top-down approaches, such as nano-printing lithography, soft lithography and capillary force lithography, require additional efforts such as specific pressure application, the delivery of specific heat quantities or covering the substrate surface with a thin adhesive film that exceeds the printing matrix adherence to the modeled substrate ( [94] and references therein). The bottom-up methods, such as self-assembly techniques, have been used to fabricate complex 3D biomimetic structures, but they showed poor precision because of uncontrollable parameters such as chemical and physical states of the surface (including defects) ( [94] and references therein).…”

“…The top-down approaches, such as nano-printing lithography, soft lithography and capillary force lithography, require additional efforts such as specific pressure application, the delivery of specific heat quantities or covering the substrate surface with a thin adhesive film that exceeds the printing matrix adherence to the modeled substrate ( [94] and references therein). The bottom-up methods, such as self-assembly techniques, have been used to fabricate complex 3D biomimetic structures, but they showed poor precision because of uncontrollable parameters such as chemical and physical states of the surface (including defects) ( [94] and references therein). Presently, an important challenge is positioning biomaterials in specific places on microstructures using hybrid methods which combine top-down and bottom-up approaches, such as premodeling, post-structuring or pre-shielding using shielding matrices and post-structuring.…”

“…From one side, some applications require the microtopographies of the 3D structures to minimize the interaction between specific cell types and structure, which is highly important for developing new devices, such as biosensors, blood-interacting devices and anti-microbial surfaces, where microorganism adhesion, such as cells or even bacteria, could limit the functionality of the device [99][100][101]. On the other side, there are specific applications that require increased cell adhesion on the 3D micro/nanostructures [94]. Each aspect can be controlled through specific microtopographies.…”