Automated measuring of mass transport through synthetic nanochannels functionalized with polyelectrolyte porous networks

Abstract

Here we demonstrate the fabrication of porous networks through self-assembly of polyelectrolytes inside nanoconfined geometries. For this purpose, nanochannel membranes fabricated through ion track-etching technique are decorated with an alternate layer-by-layer (LbL) assembly of cationic blend of poly(allylamine hydrochloride)/poly(4-vinylpyridine) (PAH/PVP) and anionic poly(acrylic acid) (PAA) polyelectrolytes. The porous network is prepared by first cross-linking the electrostatic element (PAH and PAA), followed by the removal of hydrogen-bonded polymer (PVP) from the multilayers. In membranes with a single nanochannel, the modification process is monitored by measuring changes in electrolyte ion flux, while the membrane is separating the two compartments of an electrochemical cell. In case of LbL assemblies on multiporous membranes, changes in analyte permeation are presented using an automated analysis of mass transport. Significant decrease in ion current/analyte diffusion across the membranes is caused by LbL assemblies, while an increase is noticed upon removal of hydrogen-bonded PVP from the multilayers, indicating the formation of porous networks. We believe that our presented method for the automated recording of analyte transport in combination with a new modification procedure can be potentially applicable in ionic/molecular separation, drug delivery processes, and for the monitoring of triggered releases of drugs.