Incorporation of a Hydrophobic Antibacterial Peptide into Amphiphilic Polyelectrolyte Multilayers: A Bioinspired Approach to Prepare Biocidal Thin Coatings

Abstract

A non‐water‐soluble natural antibacterial peptide, gramicidin A, has been successfully incorporated into polyelectrolyte assemblies to elaborate biocidal thin films. For this, we used a double strategy, the first step of which consists of complexing the peptide by a non‐denaturing anionic amphiphilic polysaccharide, namely a hydrophobically modified carboxymethylpullulan. We demonstrate that the use of this amphiphilic anionic derivative allows to efficiently solubilize the peptide in aqueous solution, without denaturation. The amount of peptide solubilized by the amphiphilic polysaccharide was optimized by systematically varying the hydrophobicity and the molar mass of the CMP derivative. In a second step, the negatively charged complex was layer‐by‐layer assembled with cationic poly(L‐lysine) to form biofunctionalized thin films. The amount of peptide incorporated in the multilayers was controlled by changing the number of deposited complex layers, and was quantified by UV spectroscopy. The antibacterial activity of the resulting biofunctionalized films was evidenced against a gram‐positive bacterium, E. faecalis. We demonstrated that the biocidal activity resulted from a double mechanism: contact between bacteria and the film surface, and release of the peptide into the solution surrounding the film. We also showed that the peptide was not completely removed from the film after rinsing, which insured preservation of the biocidal activity of the film surface.

Multiple Functionalities of Polyelectrolyte Multilayer Films: New Biomedical Applications

“…Other types of film, such as PGA/lysozyme, were also found to inhibit bacterial adhesion. [206] Other strategies rely on the use of anti-fungal peptides embedded in films, [207] possibly incorporated by means of an amphiphilic polyelectrolyte pre-complex with an hydrophobic peptide [208] or on Agþ ions as bactericides. In a first approach, Rubner and co-workers [209] prepared hydrogen-bonded multilayers containing Ag nanoparticles synthesized in situ and that were deposited on both planar surfaces and magnetic colloidal particles.…”

Antimicrobial Polymers in Solution and on Surfaces: Overview and Functional Principles

“…Besides chemical grafting it is often convenient to coat surfaces with antimicrobial polymers, e.g., by Layer-by-Layer (LbL)-techniques [79]. Also coatings with water-insoluble block copolymers or comb-like block copolymers containing an antimicrobial block, or with water-insoluble quarternized PEIs all from solutions in organic solvents have resulted in long-lasting antimicrobial coatings [80].…”

“…Coatings of these composites simultaneously kill microbes by releasing silver ions and upon contact with the quarternary ammonium groups [131]. Gyomard et al claim that the natural antimicrobial peptide gramicidin A immobilized into a LbL matrix kills E. faecalis cells in the surroundings upon release and in the surface-immobilized form [79].…”

Polyelectrolyte Multilayer Nanoshells With Hydrophobic Nanodomains for Delivery of Paclitaxel

“…Hammond et al used a cyclodextrin-drug complex assembled with a hydrolysable synthetic polymer (a polyβamino ester) to load and subsequently deliver the antiinflammatory drug Diclofenac [2]. Another strategy for incorporation of hydrophobic molecules within PEMs involved the use of amphiphilic polysaccharides associated with a synthetic polyelectrolyte, such as poly(ethylene imine) [34,35]. However, this strategy may suffer from problems associated with controlled release of the drug molecules at physiological pH.…”