Development of a biomimetic nanoporous membrane for the selective transport of charged proteins

We report the use of a micrometer-thick platinum-coated nanoporous membrane for the separation of differently charged proteins. A high field strength of about 25 kV m(-1) was applied, using very low transmembrane potentials of +/- 1.5 V between the platinum-coated membranes. The system mimics the cell membrane function of facilitated transport for specific solutes. The selectivity for Lys: BSA: Mb in a mixed protein solution could be tuned readily between the flux ratios of 2: 2: 1 and 96: 1: 12 respectively, by simple variation of the transmembrane potentials from + 1.5 V to -1.5 V. The experimental fluxes agreed closely with calculated fluxes derived from a simple electrophoresis-potential shielding model at favourable transmembrane potentials.