Co-immobilization of Palm and DNase I for the development of an effective anti-infective coating for catheter surfaces

Biomaterial-associated infections, in particular, catheter-associated infections (CAI) are a major problem in clinical practice due to their ability to resist antimicrobial treatment and the host immune system. This study aimed to co-immobilize the antimicrobial lipopeptide Palm and the enzyme DNase I to introduce both antimicrobial and anti-adhesive functionalities to polydimethylsiloxane (PDMS) material, using dopamine chemistry. Surface characterization confirmed the immobilization of both compounds and no leaching of Palm from the surfaces for up to 5 days. Co-immobilization of both agents resulted in a bifunctional coating with excellent surface antimicrobial and anti-biofilm properties against both Staphylococcus aureus and Pseudomonas aeruginosa. The modified surfaces demonstrated superior bio-compatibility. To better discriminate co-adhesion of both species on modified surfaces, PNA FISH (Fluorescence in situ hybridization using peptide nucleic acid probes) was employed, and results showed that P. aeruginosa was the dominant organism, with S. aureus adhering afterwards on P. aeruginosa agglomerates. Furthermore, Palm immobilization exhibited no propensity to develop bacterial resistance, as opposite to the immobilization of an antibiotic. The overall results highlighted that co-immobilization of Palm and DNase I holds great potential to be applied in the development of catheters. Statement of Significance Catheter-associated infections (CAI) are the most common hospital-acquired infections worldwide. Several coating strategies have been proposed to fight these infections but most of them present some important limitations, including the emergence of resistant bacteria and toxicity concerns. The present work describes a two-step polydopamine-based surface modification strategy to successfully co immobilize an antimicrobial peptide (Palm) and an enzyme targeting an important component of biofilm matrix (DNase I). This immobilization approach imparted polydimethylsiloxane surfaces with both anti adhesive and antimicrobial properties against the adhesion of relevant bacteria as single and dual species, with excellent stability and biocompatible and anti-biofilm properties, holding, therefore, great potential in the development of catheters able to prevent CAL (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.