Quaternary tannic acid with improved leachability and biocompatibility for antibacterial medical thermoplastic polyurethane catheters.

The surfaces of indwelling catheters offer sites for the adherence of bacteria to form biofilms, leading to various infections. Therefore, the development of antibacterial materials for catheters is imperative. In this study, combining the strong antibacterial effect of a quaternary ammonium salt (QAS) and the high biocompatibility of tannic acid (TA), we prepared a quaternary tannic acid (QTA) by grafting a synthesized quaternary ammonium salt, dimethyl dodecyl 6-bromohexyl ammonium bromide, onto TA. To prepare antibacterial catheters, QTA was blended with thermoplastic polyurethane (TPU) via melt extrusion, which is a convenient and easy-to-control process. Characterization of the TPU blends showed that compared with those of the QAS, dissolution rate and biocompatibility of QTA were significantly improved. On the premise that the introduction of QTA had only a slight effect on the original mechanical properties of pristine TPU, the prepared TPU/QTA maintained satisfactory antibacterial activities in vitro, under a flow state, as well as in vivo. The results verified that the TPU/QTA blend with a QTA content of 4% is effective, durable, stable, and non-toxic, and exhibits significant potential as a raw material for catheters.

Preparation of medical hydrophilic and antibacterial silicone rubber via surface modification.

Bacterial adhesion of medical indwelling devices shortens their service life and brings about infections in patients. The combination of hydrophilic and antibacterial modifications can not only kill the bacteria in contact with the surface, but also avoid the adhesion of dead bacteria. From this view, with a self-made quaternary ammonium salt and a zwitterion as the modifiers, a modified silicone rubber, SR-g-(DMAPS-co-QA), was prepared via random co-grafting. The static water angle test and antibacterial assays proved the enhancement of both the hydrophilicity and antibacterial activity. In addition, compared with the unmodified silicone rubber, after 7 days of co-cultivation in E. coli suspension, SR-g-(DMAPS-co-QA) demonstrated good resistance to biofilm formation. Furthermore, to simulate the real situation, its antibacterial effect in dynamic flow condition was measured, confirming that SR-g-(DMAPS-co-QA) still maintained good antibacterial performance after a 48 hour cyclic flow of E. coli bacterial suspension.