Universal Water‐Based Hydrophilization of Non‐Wettable Surfaces

ABSTRACT Despite water's central role as a universal solvent, many technologically and biologically relevant surfaces, including natural substrates, polymers, and electronic materials, present low‐energy interfaces that resist aqueous wetting. We introduce here a universal, all‐aqueous hydrophilization strategy based on regenerated silk fibroin (SF) pretreatment that renders diverse natural, living, and artificial substrates compatible with aqueous processing. Brief immersion or spraying with ultra‐dilute (0.001−0.1 w/v%) SF solutions rapidly (5 s−5 min) induces surface wetting while preserving native morphology and function. This approach enables conformal coating and direct micro‐patterning of a large library of water‐dispersible materials across two‐ and three‐dimensional hierarchically structured surfaces. The versatility of the method is demonstrated through aqueous coating of hydrophobic surfaces, including plants, vegetables, skin, feathers, hair, and synthetic substrates, as well as through direct patterning of deformable and wireless sensors on living systems. Leveraging the inherently benign properties of SF, including its edibility, biocompatibility, and aqueous processability, this approach yields a simple and scalable method for sustainable surface engineering with broad relevance to manufacturing, healthcare, food technology, and bioelectronics.