Confined mesoporous silica membranes for albumin zero-order release

In this work, the transport capabilities of anodic alumina membranes confining SBA-15-like nanochannels in their pores were investigated. The mean pore size of the confined mesophase was set around 7.0 nm, thus to achieve single passage of the selected bovine serum albumin (BSA) protein, having comparable hydrodynamic diameter, through the nanochannels. Shape, size and orientation of the manufactured mesophase were characterized by means of small-angle X-ray scattering, transmission electron microscopy and N2 adsorption/desorption at 77 K. The usage of mesostructure-containing samples having pore tuned over the size of the released BSA allowed achieving a long-term zero-order release profile by single-file diffusion up to several weeks, which delivers a constant amount of drug by unit time independently from drug concentration and drug accessible area, while control anodic alumina membranes showed a classic Fickian diffusion release. The attained BSA constant release rate was about 2 μg/day. The possibility of rate tuning could be further exploited by varying the length of the siliceous nanochannels inside the alumina pores, i.e., through different amounts of mesostructure filling the host support.

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► Usage of nanoporous silica–alumina composites as drug delivery membranes.
► Investigation about protein transport capabilities of mesophase-confining membranes.
► Long-term zero-order release profile of bovine serum albumin up to several weeks.