Prevention of pathogen colonization of medical implants is a major medical and financial issue since infection by microorganisms constitutes one of the most serious complications after surgery or critical care. Immobilization of antimicrobial molecules on biomaterials surfaces is an efficient approach to prevent biofilm formation. To the best of our knowledge, we developed herein the first self-defensive coating against both bacteria and yeasts where the release of the antimicrobial peptide is triggered by enzymatic degradation of the film due to the pathogens themselves. Biocompatible and biodegradable polysaccharide multilayer films based on functionalized hyaluronic acid by cateslytin (CTL), an endogenous host-defensive antimicrobial peptide, and chitosan (HA-CTL-C/CHI) were deposited on a planar surface with the aim of designing both antibacterial and antifungal coating. After 24 h of incubation, HA-CTL-C/CHI films fully inhibit the development of Gram-positive Staphylococcus aureus bacteria and Candida albicans yeasts, which are common and virulent pathogens agents encountered in care-associated diseases. Hyaluronidase, secreted by the pathogens, leads to the film degradation and the antimicrobial action of the peptide. Furthermore, the limited fibroblasts adhesion on HA-CTL-C/CHI films, without cytotoxicity, highlights a medically relevant application to prevent infections on catheters or tracheal tubes where fibrous tissue encapsulation is undesirable.

The alternate deposition of polyanions and polycations on a solid substrate leads to the formation of nanometer to micrometer films called Polyelectrolyte Multilayers. This step-by-step construction of organic films constitutes a method of choice to functionalize surfaces with applications ranging from optical to bioactive coatings. The method was originally developed by dipping the substrate in the different polyelectrolyte solutions. Recent advances show that spraying the polyelectrolyte solutions onto the substrate represents an appealing alternative to dipping because it is much faster and easier to adapt at an industrial level. Multilayer deposition by spraying is thus greatly gaining in interest. Here we review the current literature on this deposition method. After a brief history of polyelectrolyte multilayers to place the spraying method in its context, we review the fundamental issues that have been addresses so far. We then give an overview the different fields where the method has been applied.