Spatially Defined, High‐Contrast, and Deformation‐Free Dopamine Subtractive Thermal Transfer Printing Using a Nonelastomeric Polymeric Mold and Its Multifunctional Applications

Here, a spatially defined high‐contrast subtractive strategy of patterning dopamine from one hard substrate onto another via thermal transfer printing is presented. Dopamine is deposited on a bare thermoplastic and then transfer‐printed onto another, on which polyethylenimine (PEI), an amine‐rich compound that acts as an adhesive, is coated. Schiff base reaction between the dopamine and amine functionalities of PEI allows for dopamine transfer from one substrate to another without pattern collapse and permits high transfer efficiency, leaving behind only the defined dopamine patterns on the bare thermoplastic substrates, where dopamine is initially coated physically. Water contact angle measurement and X‐ray photoelectron spectroscopy confirm the successful dopamine transfer. The practical applicability of this patterning method is verified by culturing human umbilical vein endothelial cells, selectively embedding micro beads into the dopamine‐coated microwell arrays formed on a hydrophobic substrate, and selective electroless deposition of silver onto the dopamine‐coated regions. This subtractive patterning method guarantees high pattern fidelity with simple operation, high homogeneity and visibility in the patterned area, and high‐contrast wettability in regard to its background, revealing its promise for future applications in biomolecule patterning and microarray chip construction.