Tailored design of mechanically sensitive biocatalytic assemblies based on polyelectrolyte multilayers

Abstract

Mechanically sensitive surfaces responding to mechanical forces constitute an attractive emerging field of research. This requires the engineering of complex surfaces with finely controlled properties, especially regarding the permeability behaviour towards specific molecules. Here we designed such surfaces using polyelectrolyte multilayer nanostructures. Polylysine/hyaluronic acid multilayer films were used as a micro-container of enzymes and denser multilayers deposited on top of the reservoir were tailored to control their permeability. We find that permeability towards fluorescein diphosphate (FDP) not only depends on the number of bilayers constituting the barrier but more surprisingly on the deposition time of the polyelectrolytes during the barrier buildup, a long contact time (10 min) leading to porous barriers. This effect is explained by diffusion and exchange processes taking place in the reservoir during the buildup process. For films composed of a non-permeable barrier towards enzymatic substrate FDP, we tested the enzymatic activity when mechanical stretching was applied to the architecture. Under stretch and in the presence of FDP on top of the film, the catalytic activity was switched on. These biologically inspired surfaces constitute a first step to the development of novel platforms able to trigger and to modulate chemical reactions under a mechanical stimulus.