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.

We report on the preparation of layer-by-layer (LbL) assemblies based on anionic hydrophobically modified polysaccharides and different polycations. We systematically investigate the influence of the effect of the hydrophobicity of the polysaccharide derivatives on the multilayer buildup. We provide clear evidence that the presence of hydrophobic interactions contributes strongly to stabilize the adsorbed layers. In addition, the correlation between the study of the multilayer growth and of the solutions properties of the amphiphilic derivatives shows that the thickness of adsorbed layers is directly determined by the conformation of amphiphilic chains in solution. These results are in agreement with the presence of hydrophobic microdomains in the films.

We report on the loading and release behaviors of polyelectrolyte multilayers based on hydrophobically modified carboxymethylpullulan (CMP) derivatives and poly(ethyleneimine) (PEI) toward hydrophobic dye. The dye-loaded films are obtained according to two different protocols: (i) the postdiffusion approach, which involves the diffusion of the dye within preassembled self-assemblies, and (ii) the precomplexation method, which requires the formation of a water-soluble amphiphilic CMP derivative-dye complex before the multilayer buildup. In both cases, we provide clear evidence for the entrapment of the dye in hydrophobic nanoreservoirs resulting from the aggregation of decyl pendent groups grafted on CMP chains. We show that the loading capacity of the multilayers, as well as their release behavior, can be tuned by varying the grafting degree of CMP chains. Moreover, we demonstrate the possibility to trigger the subsequent release of the loaded dye molecules by varying the composition of the surrounding solution.