Ceragenin Nanogel Coating Prevents Biofilms Formation on Urinary Catheters

Abstract

Catheter-associated urinary tract infections (CAUTIs) account for 40% of hospital-acquired infections, increasing health risks, patient discomfort, morbidity, and hospitalisation time. Bacterial colonisation may occur both during catheter insertion and prolonged catheterization by microorganisms in the urinary tract, consequently, increasing the bacteriuria risk due to biofilm formation. Nanogels, a class of soft nanocarriers, offer remarkable versatility for developing functional coatings on indwelling medical devices that can efficiently prevent biofilm formation. In this study, we designed an antibacterial and antibiofilm coating by leveraging the ultrasound-assisted assembly and nanogel self-organization on silicone catheters. The nanogel comprising biocompatible gum arabic and poly(diallyldimethylammonium chloride) was used to encapsulate a synthetic broad-spectrum antimicrobial peptide mimetic ceragenin (CSA-131). A coating from this bioactive nanogel was sonochemically built on the catheters without any prior surface modification. In vitro and in vivo assays showed that the coating provided antimicrobial and antibiofilm activity for up to 7 days of catheterization, next to catheter lubricity. Cytotoxicity assessment confirmed the absence of toxic effects, underscoring the biocompatibility of the coating formulation. These findings highlighted the potential of nanogels, combined with ultrasound technology, as an innovative approach for durable antimicrobial and antibiofilm functionalization of urinary catheters, particularly susceptible to colonisation by microorganisms upon catheterization.

Keywords: antimicrobial and antibiofilm coating; ceragenin; nanogels; self-assembly; ultrasound; urinary catheters.

1

Schematic presentation of the approach for development of CeNGs-based nanoenabled coating for biofilm prevention on urinary catheters: (A) Chemical structures of the used components (essential charged groups for polyelectrolyte complexations are indicated with red arrows); (B) Polyelectrolyte complexation leads to the formation of nanogels (CeNGs); (C) CeNGs coating is formed by ultrasound deposition of the formed complexes; (D) The bactericide effect of the coating is due to Ceragenin (CSA-131) release and contact killing mechanism.

2

(A) SEM micrographs of nanogels without (WNGs) and with ceragenin (CeNGs). (B) Antimicrobial activity of WNGs and CeNGs toward and . (C) Quorum sensing inhibition in by NGs and CeNGs. (D) and biofilm prevention by WNGs and CeNGs.

3

(A) FTIR-ATR spectra of pristine PDMS (Pristine), NGs coating (WNGs), and CeNGs coatings. (B) High-resolution XPS spectra of C 1s, (C) high-resolution XPS spectra of N 1s.

4

(A) SEM micrographs of pristine and coated substrates. (B)­Three-dimensional AFM images of untreated silicone (Pristine), coated with NGs without ceragenin (WNGs) and ceragenin-loaded NGs (CeNGs). Roughness profile of the samples.

5

(A) WCA measurements of the NG-enabled coatings before and after 7 days of incubation in deionized water (n = 10). Solid-colored bars represent fresh samples (nonincubated), while diagonally hatched bars correspond to samples incubated for 7 days. (B) Release profile of ceragenin in PBS after 7 days at 37 °C (n = 3).

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Lubricity of the CeNGs coating (A) CoF study of nontreated and coated silicone (n = 3). (B) Static friction. (C) Dynamic friction.

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Antibacterial activity of NGs coatings against and (n = 3). Solid-colored bars represent and diagonally hatched bars correspond to .

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Antibiofilm properties of NGs coatings at static conditions (24 h). (A) Biofilm biomass inhibition. (B) Cell viability of and in biofilms cultured for 24 h on different coatings under static conditions (n = 3). Solid-colored bars represent and diagonally hatched bars correspond to . (C) Fluorescence micrographs of live (green) and dead (red) and cells. (D) SEM micrographs of biofilms on pristine and NGs coated substrates.

9

Antibiofilm properties of CeNGs coatings under dynamic conditions. (A) Schematic representation of the experimental setup used for the assessment of the biofilm formation under dynamic conditions. (B) Fluorescence micrographs showing live (green) and dead (red) bacteria on the lumen and external surface of catheters after exposure to a mixed bacteria culture for 7 days at 37 °C in dynamic conditions.

10

Viability of human fibroblast and keratinocyte cell lines upon exposure to pristine and coated silicone materials. Solid-colored bars represent fibroblast and diagonally hatched bars correspond to keratinocytes. (A) AlamarBlue and (B) Micrographs of samples stained with Live/Dead kit assays. The green and red fluorescence signals are overlaid (n = 3).

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Histology of urethra (A,C) and kidneys (B,D) of male rabbits: (A,B) rabbits with control catheters; (C,D)­rabbits with CeNGs-coated catheters. Urethral epithelium (blue arrow). Renal corpuscles (black arrow).