A Universal and Versatile Zwitterionic Coating for Blood‐Contacting Catheters with Long Lengths and Complex Geometries

Abstract Blood‐contacting catheters are highly susceptible to thrombus formation, making heparin coating essential for reducing clinical complications. However, the limitations of heparin coatings have spurred significant efforts to develop alternative strategies. This study demonstrates a cost‐efficient, mechanically viable, and universal zwitterion coating approach for long and complex catheters with near‐zero fouling, super anticoagulation, and selective biocapturing. Leveraging the synergistic action of side groups, a wet‐adhesive initiator‐bearing polymer rapidly assembles on catheter surfaces in aqueous environments, facilitating the grafting of superhydrophilic and zwitterionic polymers onto catheter inner walls. This strategy demonstrates broad adaptability, successfully applying to ten substrates and showing exceptional versatility in modifying catheters and joints of various shapes and sizes. These coatings exhibit near‐zero protein fouling across a broad pH range, and superior resistance to blood cells and bacteria. Furthermore, they maintain excellent stability under simulated bloodstream without compromising anticoagulant performance. Beyond antifouling properties, this method enables the construction of highly selective bio‐interaction networks on catheter inner walls, allowing precise capture of circulating tumor cells from blood. This zwitterion coating technique, with its rapid modification, robust anticoagulant properties, and customizable bio‐functionality, provides an attractive solution for, beyond catheters, a wide range of medical devices that must perform in challenging biological environments.