Bioinspired Patterning with Extreme Wettability Contrast on TiO2 Nanotube Array Surface: A Versatile Platform for Biomedical Applications

Binary wettability patterned surfaces with extremely high wetting contrasts can be found in nature on living creatures. They offer a versatile platform for microfluidic management. In this work, a facile approach to fabricating erasable and rewritable surface patterns with extreme wettability contrasts (superhydrophilic/superhydrophobic) on a TiO₂ nanotube array (TNA) surface through self‐assembly and photocatalytic lithography is reported. The multifunctional micropatterned superhydrophobic TNA surface can act as a 2D scaffold for site‐selective cell immobilization and reversible protein absorption. Most importantly, such a high‐contrast wettability template can be used to construct various well‐defined 3D functional patterns, such as calcium phosphate, silver nanoparticles, drugs, and biomolecules in a highly selective manner. The 3D functional patterns would be a versatile platform in a wide range of applications, especial for biomedical devices (e.g., high‐throughput molecular sensing, targeted antibacterials, and drug delivery). In a proof‐of‐concept study, the surface‐enhanced Raman scattering and antibacterial performance of the fabricated 3D AgNP@TNA pattern, and the targeted drug delivery for site‐specific and high‐sensitivity cancer cell assays was investigated.