Design of an Antifungal Surface Embedding Liposomal Amphotericin B Through a Mussel Adhesive-Inspired Coating Strategy

Abstract

Microbial colonization of urinary catheters remains a serious problem for medicine as it often leads to biofilm formation and infection. Among the approaches reported to deal with this problem, surfaces functionalization to render them with antimicrobial characteristics, comprises the most promising one. Most of these strategies, however, are designed to target bacterial biofilms, while fungal biofilms are much less taken into account. In real-life settings, fungi will be inevitably found in consortium with bacteria, especially in the field of biomaterials. The development of antifungal coating strategies to be combined with antibacterial approaches will be pivotal for the fight of biomaterial-associated infections. The main goal of the present study was, therefore, to engineer an effective strategy for the immobilization of liposomal amphotericin B (LAmB) on polydimethylsiloxane (PDMS) surfaces to prevent Candida albicans colonization. Immobilization was performed using a two-step mussel-inspired coating strategy, in which PDMS is first immersed in dopamine solution. Its polymerization results in the deposition of a thin adherent film, called polydopamine (pDA), which allowed the incorporation of LAmB, afterwards. Different concentrations of LAmB were screened in order to obtain a contact-killing surface with no release of LAmB. Surface characterization confirmed the polymerization of dopamine and further functionalization with LAmB yielded surfaces with less roughness and more hydrophilic features. The proposed coating strategy rendered the surfaces of PDMS with the ability to prevent the attachment of C. albicans and kill the adherent cells, without toxicity toward mammalian cells. Overall results showed that LAmB immobilization on a surface retained its antifungal activity and reduced toxicity, holding therefore a great potential to be applied for the design of urinary catheters. Since the sessile communities commonly found associated to these devices exhibit a polymicrobial nature, the next challenge will be to co-immobilize LAmB with antibacterial agents to prevent the establishment of catheter-associated urinary tract infections (CAUTI).

Tailoring the immobilization and release of chlorhexidine using dopamine chemistry to fight infections associated to orthopedic devices

“…Antimicrobial properties of prepared surfaces were evaluated as previously reported, with some modifications [27]. Briefly, 20 μL of a bacterial suspension adjusted to approximately 10 6 CFU mL − 1 were added on top of each surface and incubated under static conditions at 37 • C. When the drop was dried, coupons were placed on a TSA plate, with the face exposed to bacterial suspension in contact with the agar, and they were incubated at 37 • C for 24 h. Bacterial growth was then evaluated for the tested surfaces and tabulated as "+" for growth and "-" for no visible growth.…”

“…This coating strategy, based on a mussel adhesive protein, was first described in 2007 by Messersmith and co-workers and it comprises the immersion of substrates in an alkaline solution of dopamine, which selfpolymerization results in the deposition of an adhesive film with nanometer thickness [26]. It has been successfully applied for the immobilization of antifungals, antimicrobial peptides and enzymes to render the surfaces of biomaterials with anti-infective properties [27][28][29].…”

Recent Advances in a Polydopamine-Mediated Antimicrobial Adhesion System

“…PDA deposited onto the polydimethylsiloxane (PDMS) surface has been used to tether synthetic antimicrobial cysteinylated tryptophane–arginine-rich peptide (CWFWKWWRRRRR-NH 2 ) (CWR11) that displayed antimicrobial functionality over 21 days on catheter-relevant surfaces to combat catheter-associated urinary tract infections ( Lim et al, 2015 ). Similarly, immobilization of liposomal amphotericin B (LAmB) on a PDA-coated PDMS surface, a material commonly used in the manufacturing of urinary catheters, was shown to impart the ability to resist Candida albicans colonization ( Alves et al, 2019 ).…”

Advances in Biomaterials for the Prevention and Disruption of Candida Biofilms

“…AmBisome has a strong affinity for Candida cells, electrostatically interacting with the cell wall before binding to the cell membrane at sites of high ergosterol content ( Soo Hoo, 2017 ), which may promote their activity against biofilm Candida cells, which have been shown to have thicker cell walls ( Nett et al, 2007 ). Liposomal amphotericin B has also been immobilized on biomaterial surfaces for the prevention of biofilm formation ( Alves et al, 2019 ). In our recent work, we have shown that liposomes encapsulating anidulafungin, the latest echinocandin approved by the FDA, are effective against mature C. albicans biofilms, reducing metabolic activity to approximately 46% compared to untreated controls over 24 h. Biofilms treated with an equivalent concentration of free anidulafungin did not reduce metabolic activity, further emphasizing the importance of nanoformulations in the treatment of Candida biofilms ( Vera-González et al, 2020 ).…”