Confined diffusion in ordered nanoporous alumina membranes

The confined diffusion behavior of fluorescent probe molecules inside nanoporous alumina membranes was studied by using nanopores-confinement technique of fluorescence correlation spectroscopy (FCS). The ordered porous alumina membranes were prepared with a pore diameter of 35-40 nm, porosity of 20-25%, and thickness of 35 μm. The alumina membranes were soaked in bovine serum albumine (BSA) solution to prevent nonspecific adsorption of analytes. FCS results show that the functionalized nanoporous alumina membranes are applied for single-molecule detection in nanoscale confinement. The confinement results lead to apparent 1D diffusion of alumina membranes with 19-fold prolonged diffusion times. The results also show that the sensitivity of alumina membrane sticking to pore walls depends on the chemical composition of the fluorescent probe molecules inside nanoporous alumina membranes.