Fabrication of highly porous polymeric coatings loaded with rifampicin for preventing catheter-associated urinary tract infections

Abstract

Developing anti-infective catheters by applying coatings loaded with antimicrobial drugs has been proven to be a promising strategy in preventing catheter-associated urinary tract infections. In the current study, pore-formation techniques based on the breath fig. (BF) process were utilized to shape highly porous coating of polylactic acid (PLA) with multi-layered arrays of micro-pores. Inverse emulsion (Ie) and vapor-induced phase separation (VIPS) were combined with BF process to achieve 3D pore-formation on the planar substrate and urinary catheter, respectively. By tuning the water content of the casting emulsion in the Ie-BF process or the solvent ratio of the treating solvent pair in the BF-VIPS process, the obtained porous structure of the coating could be readily regulated. Rifampicin (RIF) was selected as the antimicrobial drug to be loaded into the porous coatings via pre-mixing or post-immersion (wicking). Remarkably uniform distribution of RIF within the porous PLA matrix was confirmed. The drug release test of RIF showed an early-stage burst release after 24 h, followed by rather sustained release behavior for as long as 28 days. The cumulative release rate of the Ie-BF coatings increased with higher porosity, reaching the highest rate of 87.45 % after 28 days. The Ie-BF coatings with high porosity and long-term cumulative release rate exhibited excellent antibacterial effect, reducing over 99.99 % of Pseudomonas aeruginosa adhesion and 92.39 % of biofilm formation after 8-day incubation, compared to the pore-less RIF-loaded coating. While the urinary catheter coated with the BF-VIPS coating also demonstrated remarkable bacterial inhibition over Pseudomonas aeruginosa and Staphylococcus aureus.