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In this work, we fabricate a hexagonal array of pillars where each pillar has a “micro-hoodoo” shape, i.e., a reentrant cross section. The shape of the pillars makes them more resilient towards total wetting, i.e., transition from a Cassie-Baxter non-wetting state to a Wenzel wetting state. We show the single-step fabrication of 4 × 4 mm2 arrays by two-photon polymerization direct laser writing of the polydimethylsiloxane (PDMS)-derived commercial resin IP-PDMS. The use of a hydrophobic resin for rapid prototyping of reentrant structures enables the fabrication of surfaces patterns displaying superhydrophobic behavior despite the use of relatively simple structures, i.e. with a single reentrant surface. By changing the size of the micro-hoodoos and the packing density of the arrays, we map wetting behaviors ranging from the pinning of water droplets in Wenzel state to non-wetting Cassie-Baxter states. The measured contact angles follow quite well the theoretical results obtained by minimizing Gibbs free energy using the Wenzel, Cassie-Baxter and partial wetting theories. Among the tested micropatterns, five exhibited superhydrophobic properties, with a static contact angle with water as high as 158.1° ± 7.1°. This is the first demonstration of superhydrophobic surfaces produced by two-photon polymerization direct laser writing of PDMS in a single-step process.

Additive manufacturing based on direct laser writing two-photon polymerization facilitates the fabrication of microstructures with full 3D design freedom. Here, this fabrication technique is exploited for engineering scaffolds accurately mimicking the shape and size of three types of human cells. The human cell models employed in the study were chosen to include a range of dimensions and different identifiable features to highlight the versatility of this fabrication approach, yet other cell shapes can easily be fabricated in similar manner. The design and fabrication parameters for the additive manufacturing process were optimized to obtain polymeric scaffolds with biomimetic shapes. After fabrication, the cell scaffolds were converted to polymer-cushioned model cell membranes through layer-by-layer functionalization with a cationic polymer and a lipid bilayer. Scaffold functionalization was verified using confocal laser scanning microscopy. Polymer-cushioned model cell membranes supported on 3D scaffolds mimicking the shape of human cells are particularly suitable for membrane interaction studies where membrane curvature plays an important role. The aim of this study is to demonstrate the engineering of biomimetic cell membranes by high-resolution additive manufacturing combined with surface functionalization. The interdisciplinary approach highlights the value of additive manufacturing as technological solution for challenges encountered in biomedical studies.