Microtopographic superhydrophobic polymer surface to prevent urinary tract infections causing nosocomial drug-resistant bacterial adhesion

Catheter-associated urinary tract infections (CAUTIs) are one of the most prevalent forms of healthcare-associated infections worldwide. Recurrent episodes of infections and development of antibiotic resistance/tolerance among biofilm-forming bacteria are well documented. We developed a simple method of making superhydrophobic micro-structured antibacterial polymer surfaces for coating-free catheters. A two-step fabrication approach was used to turn the hydrophobic polydimethylsiloxane (PDMS) into superhydrophobic surfaces. The nanosecond pulsed Nd:YAG laser was used to fabricate two types of structures (holes and grooves) on a steel mold. The soft-molding technique was adopted to replicate these structures on PDMS films. The pillar structured PDMS surface exhibited a water droplet contact angle (WDCA) of 169○ ± 3° with a low sliding angle of 12○, whereas the grooved surface had 142○ ± 5° contact angle. Moreover, the Luria Broth which is media for bacterial growth shows contact angle of 141○ ± 2° and 120○ ± 3°, respectively. Theoretically, the micro-pillar structures with selected dimensions could sustain the Cassie–Baxter state. The crystal violet binding assay was used to assess the anti-biofilm activity of structured surfaces (grooved and pillared) against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), as well as clinical isolates of Klebsiella pneumonia (K. pneumoniae), E. coli, and S. aureus. Furthermore, the attachment and interaction of bacteria with surfaces were investigated through filed emission scanning electronic microscope (FE-SEM) and confocal microscopy. Overall, the pillar-structured surface reduces the average bacterial attachment more efficiently than a grooved surface (>80% vs. >50% reduction) compared to a plain PDMS surface due to its higher water-repellent property. This work will give new insights into the development of coating-free, long-lasting antibacterial surfaces for polymeric medical devices.