Nature of the Polyanion Governs the Antimicrobial Properties of Poly(arginine)/Polyanion Multilayer Films

Coatings with antimicrobial properties are garnering interest to prevent implant-associated infections. Recently, we showed that poly(arginine)/hyaluronic acid (PAR/HA) multilayers built with PAR chains constituted from 30 arginine residues (PAR30) have strong antimicrobial properties through a contact-killing mechanism. This property is due to the ability of PAR30 chains, when associated with HA, to diffuse in the multilayer. Here, we investigate the effect of the nature of the polyanion on the antimicrobial activity of (PAR30/polyanion) multilayers. Four polysaccharides, one polypeptide, and one synthetic polyelectrolyte are investigated. Surprisingly, only HA leads to films with antimicrobial character. We relate this property to the strong diffusion capacity of PAR30 chains in (PAR30/HA) multilayers compared to their diffusion ability in the other (PAR30/polyanion) films. Through isothermal microcalorimetry experiments, we also demonstrate that interactions in solutions of PAR30 chains with the different polyanions are characterized by a negative reaction enthalpy for all of the investigated polyanions except for HA, where the enthalpy of reaction is positive. Moreover, the molecular weight of HA is not a key parameter for the diffusion ability of PAR chains or for the bioactivity of the film. These results constitute an important step toward the establishment of rules to design contact-killing antimicrobial polyelectrolyte multilayers.