Layered Inorganic/Enzyme Nanohybrids with Selectivity and Structural Stability upon Interacting with Biomolecules

Effective intercalation of protein molecules within the galleries of montmorillonites can be achieved via simple space enlarging and exchange processes while retaining the native conformation of the guest protein and the multilayered structure of the bioinert host plates. The capacity of accommodating protein molecules in the galleries can be markedly larger than that governed by the Langmuir-type adsorption of protein molecules on the external surfaces of particles. The basal spacing in the multilayered structure of clay is abruptly enlarged when the extent of protein intercalation increases to a critical point. Beyond this critical point, the nanohybrids show well-preserved catalytic activity in hydrolyzing small substrates while establishing a barrier to interactions with large biomacromolecules. Furthermore, the structural stability of the inorganic/organic nanohybrids is enhanced such that neither exchange of biomolecules nor exfoliation of layered clay particles occurs when exposed to other proteins. The results indicate that, through the benign accommodation of protein species between the inorganic platelets, this nanoscaled manipulation of protein functions can be highly useful in developing new inorganic/enzyme nanohybrids for protein therapeutics and tissue engineering.