Using modified β-galactosidase covalently linked to cross-linked polyelectrolyte multilayers (PEM), catalytically active materials have been designed. Their enzymatic activity can be modulated, partially in a reversible way, simply by stretching. This strategy, based on enzyme conformational changes, constitutes a new tool for the development of biocatalytic mechano-responsive materials.

Tuning the dihedral angle (DA) of axially chiral compounds can impact biological activity,c atalyst efficiency, molecular motor performance,orchiroptical properties.Herein, we report gradual, controlled, and reversible changes in molecular conformation of ac ovalentlyl inked binaphthyl moiety within a3 Dp olymeric network by application of amacroscopic stretching force.Wemanaged direct observation of DA changes by measuring the circular dichroism signal of an optically pure BINOL-crosslinked elastomer network. Stretching the elastomer resulted in aw idening of the DA between naphthyl rings when the BINOL was doubly grafted to the elastomer network;noeffect was observed when asingle naphthyl ring of the BINOL was grafted to the elastomer network. We have determined that ca. 170 %e xtension of the elastomers led to the transfer of am echanical force to the BINOL moiety of 2.5 kcal mol À1 À1 (ca. 175 pN) in magnitude and results in the opening of the DA of BINOL up to 1308 8.

We investigate the effect of stretching on the secondary structure of cross-linked poly(l-lysine)/hyaluronic acid (PLL/HA) multilayers. We show that stretching these films induces changes in the secondary structure of PLL chains. Our results suggest that not only α- but also 310-helices might form in the film under stretching. Such 310-helices have never been observed for PLL so far. These changes of the secondary structure of PLL are reversible, i.e., when returning to the nonstretched state one recovers the initial film structure. Using molecular dynamics simulations of chains composed of 20 l-lysine residues (PLL20), we find that these chains never adopt a helical conformation in water. In contrast, when the end-to-end distance of the chains is restrained to values smaller than the mean end-to-end distance of free chains, a distance domain rarely explored by the free chains, helical conformations become accessible. Moreover, the formation of not only α- but also 310-helices is predicted by the simulations. These results suggest that the change of the end-to-end distance of PLL chains in the stretched film is at the origin of the helix formation.