Nitric Oxide-Releasing Thixotropic Hydrogels as Antibacterial and Hemocompatible Catheter Locks

Catheters are indispensable medical tools for accessing blood vessels, hollow organs, and body cavities to facilitate medication delivery and fluid drainage. However, they also serve as major entry points for bacterial contamination and trigger foreign body responses, necessitating locking strategies that are both bactericidal and biocompatible. This study introduces the first gel-based catheter lock, in contrast to conventional liquid locks. The gel is a poloxamer-based hydrogel formulated with 2-hydroxypropyl α-cyclodextrin (HP-αCD). HP-αCD forms supramolecular complexes with the poloxamer to enhance gelation, and with the nitric oxide (NO) donor to modulate NO release kinetics. This thixotropic gel can be injected into the catheter lumen when the catheter is not in use and withdrawn when vascular access is needed. The gel matrix provides a physical barrier that slows bacterial migration and minimizes drug loss. Simultaneously, the released NO functions as a broad-spectrum antimicrobial agent, effectively preventing biofilm formation on both the internal and external surfaces of the catheter. The NO-releasing hydrogel also demonstrates excellent hemocompatibility and reduces clot adhesion. Together, the gel-based lock offers a promising strategy for more effective catheter maintenance and represents a new application of hydrogels.