Ultrasonic spray coating of dextran-polyvinylamine composite for self-leveling, substrate-independent surface modification

The surface coating of dextran offers significant advantages for biomedical applications due to its biocompatibility, biodegradability, and antifouling properties; however, its poor substrate adhesion remains a challenge. Herein, we employ ultrasonic spray coating to fabricate dextran composite nanofilms with polyvinylamine (PVAm), resulting in a dextran-PVAm composite nanocoating. This process utilizes a material-independent nanocoating strategy based on Fe(III) and tannic acid to anchor the dextran-PVAm composite onto various substrates, including metal, glass, and plastic surfaces. Compared to immersive and spin coating, ultrasonic spray coating uniquely facilitates a self-leveling effect, yielding superior surface uniformity with exceptionally low roughness. The resulting ultrasmooth dextran-PVAm nanocoating further transforms into organic–inorganic hybrid nanofilms through surface-promoted silicification. Furthermore, we demonstrate its applicability to metal stents for the immobilization of the FDA-approved near-infrared fluorescent dye indocyanine green (ICG), by incorporating ICG-conjugated PVAm as a composite-forming material. The dextran-PVAm composite nanocoating exhibits remarkable scalability and precise maneuverability, owing to the inherent advantages of ultrasonic spray coating. These attributes render it highly suitable for advanced biomedical applications, including functional coatings for medical devices.