Intraluminal Release of an Antifungal β-Peptide Enhances the Antifungal and Anti-Biofilm Activities of Multilayer-Coated Catheters in a Rat Model of Venous Catheter Infection

Abstract

Candida albicans is the most prevalent cause of hospital-acquired fungal infections and forms biofilms on indwelling medical devices that are notoriously difficult to treat or remove. We recently demonstrated that the colonization of C. albicans on the surfaces of catheter tube segments can be reduced in vitro by coating them with polyelectrolyte multilayers (PEMs) that release a potent antifungal β-peptide. Here, we report on the impact of polymer structure and film composition on both the inherent and β-peptide-mediated ability of PEM-coated catheters to prevent or reduce the formation of C. albicans biofilms in vitro and in vivo using a rat model of central venous catheter infection. Coatings fabricated using polysaccharide-based components [hyaluronic acid (HA) and chitosan (CH)] and coatings fabricated using polypeptide-based components [poly-l-lysine (PLL) and poly-l-glutamic acid (PGA)] both served as reservoirs for the loading and sustained release of β-peptide, but differed substantially in loading and release profiles and in their inherent antifungal properties (e.g., the ability to prevent colonization and biofilm growth in the absence of β-peptide). In particular, CH/HA films exhibited inherent antifungal and antibiofilm behaviors in vitro and in vivo, a result we attribute to the incorporation of CH, a weak polycation demonstrated to exhibit antimicrobial properties in other contexts. The antifungal properties of both types of films were improved substantially when β-peptide was incorporated. Catheter segments coated with β-peptide-loaded CH/HA and PLL/PGA films were both strongly antifungal against planktonic C. albicans and the formation of surface-associated biofilms in vitro and in vivo. Our results demonstrate that PEM coatings provide a useful platform for the design of new antifungal materials, and suggest opportunities to design multifunctional or dual-action platforms to prevent or reduce the severity of fungal infections in applied biomedical contexts or other areas in which fungal biofilms are endemic.

Antifungal activity of a β-peptide in synthetic urine media: Toward materials-based approaches to reducing catheter-associated urinary tract fungal infections

“…However, all three catheter tubes coated with HA/CH films and loaded with β-peptide showed levels of fluorescence that were qualitatively similar to each other and greater than those observed in catheter tubes coated with β-peptide-loaded PGA/PLL films (Figure 3D–F). The higher apparent loading in the catheters coated with HA/CH films is consistent with our previous observations demonstrating that HA/CH films fabricated in polyethylene catheter tubes were thicker than those fabricated using PGA/PLL (e.g., 1340 ± 240 nm vs. 710 ± 50 nm) and released more β-peptide (e.g., ~ 4.3 µg vs. ~2.7 µg) under otherwise identical conditions [38]. In all cases, uncoated control tubes infused with β-peptide exhibited negligible fluorescence (Figure 3G–I).…”

“…We used two model biocompatible polyelectrolyte multilayer coating systems—a polypeptide-based system consisting of poly-L-lysine (PLL) and poly-L-glutamic acid (PGA) [37, 44–46], and a polysaccharide-based system consisting of hyaluronic acid (HA) and chitosan (CH) [38, 47–50] — to fabricate polymeric thin film coatings on the intraluminal walls of urinary catheters. Using a previously developed fill-and-purge method [37, 38], we fabricated PGA/PLL and HA/CH multilayers inside polyurethane, polyethylene, and silicone tubes commonly used to manufacture urinary catheters.…”

“…Using a previously developed fill-and-purge method [37, 38], we fabricated PGA/PLL and HA/CH multilayers inside polyurethane, polyethylene, and silicone tubes commonly used to manufacture urinary catheters. β-Peptide was loaded into the coated catheter tubes by infusing β-peptide 1 into the tubes and allowing it to infiltrate the coatings by diffusion for 24 hours (see Materials and Methods for additional details of β-peptide loading).…”

“…The tubes were then rinsed twice using a solution of NaCl (0.15 M) in water for 1 min each. PEM films were then deposited using a previously developed ‘fill-and-purge’ approach [37, 38]. Briefly, (i) a solution of negatively charged polymer (PGA or HA) was infused into the tube and allowed to incubate (for 3 min or 5 min, respectively), (ii) tubes were rinsed twice by infusing a rinse solution of NaCl solution in water (0.15 M) for 1 min each, (iii) tubes were infused with a solution of positively charged polymer (PLL or CH for 3 min or 5 min, respectively), and (iv) tubes were rinsed again in the manner described in step (ii).…”

“…Briefly, (i) a solution of negatively charged polymer (PGA or HA) was infused into the tube and allowed to incubate (for 3 min or 5 min, respectively), (ii) tubes were rinsed twice by infusing a rinse solution of NaCl solution in water (0.15 M) for 1 min each, (iii) tubes were infused with a solution of positively charged polymer (PLL or CH for 3 min or 5 min, respectively), and (iv) tubes were rinsed again in the manner described in step (ii). This was repeated until 19.5 PGA/PLL or HA/CH bilayers had been deposited (such that all films were terminated by the deposition of a final layer of the cationic polymer, as reported previously [37, 38]).…”