Sodium Carboxymethylcellulose/Polydopamine Biocellulose Coatings with Enhanced Wet Stability for Implantable Medical Devices

Sodium carboxymethylcellulose (CMC) is a biocompatible and biodegradable derivative of cellulose, making it a promising material for biomedical applications. However, its poor stability in aqueous environments has significantly limited its use in long-term biomedical devices. Here, we present for the first time a simple and controllable method to enhance the wet stability of CMC coatings by cross-linking of CMC and polydopamine (PDA) and self-polymerization of PDA for widespread applications in biomedical devices. A series of CMC/PDA coatings were fabricated on the initial PDA layers by using dip coating and subsequently heated at 200 °C. The performance of the CMC/PDA coatings and their chemical and structural stability in aqueous media have been systematically analyzed, and the mechanisms underpinning their robust performance have been revealed. FITR, X-ray photoelectron spectroscopy (XPS), and gel permeation chromatography (GPC) results showed that CMC/PDA coatings involved amidation and esterification reactions as well as self-polymerization of PDA. Degradation studies in phosphate-buffered saline (PBS) solution at 37 °C indicated degradation via ester and amide bond cleavage, with the stability of CMC/PDA coatings surpassing that of individual PDA and CMC coatings over a 30-day immersion period. The CMC/PDA coating with a CMC concentration of 15 mg/mL exhibited the highest adhesion strength in an aqueous environment, which was attributed to the high cross-linking of CMC and PDA, as well as the intrinsic stability of PDA. The CMC/PDA coatings demonstrated favorable viability, growth, and proliferation of endothelial cells. The stable and biocompatible biocellulose coatings can be easily applied from aqueous solutions onto almost any type of solid metal and ceramic material, providing a promising dimension for surface engineering of vascular scaffolds and tissue engineering constructs.