Mesoporous protein thin films for molecule delivery

Abstract

A simple and easy method was developed for preparation of large-scale free-standing mesoporous protein thin films through a filtration technique by using ultrathin metal hydroxide nanostrands as frames and pore templates. Composite nanofibrous dispersions of nanostrands and proteins were formed by assembling negatively charged protein on the highly positively charged nanostrand surfaces. These dispersions were filtered on a porous substrate. After partially cross-linking the amino groups of the proteins, removing the nanostrands and peeling off from the substrate, free-standing mesoporous protein films were obtained. These films repeatedly demonstrated efficient loading and releasing performance of dye molecules by pH controlling. The delivery capacity was 33.5% relative to the weight of the matrix. This value is several times higher than that of active carbon powders as well as that of metal hydroxide sludge. At pH lower than the isoelectic point of protein, the negatively charged dye molecules were loaded. Subsequently, the preloaded dye molecules were released at pH higher than the isoelectric point of protein. Furthermore, reversible delivery of doxorubicin drug molecules was realized by using these mesoporous protein thin films under physiological conditions. These films hold promising applications for recovering dyes from the dye waste water, and for efficient drug delivery platforms with controllable releasing speed.