Molecular transport of proteins through nanoporous membranes fabricated by interferometric lithography

Abstract

Millimeter sized arrays of uniformly-distributed nanopores (180-220 nm) were created in thin (200 nm) silicon nitride membranes using interferometric lithography. Molecular transport properties of the fabricated devices were investigated experimentally and compared with those of state-of-the-art polycarbonate track etched membranes. Two similarly-sized proteins, bovine serum albumin (BSA) and bovine hemoglobin (BHb), were used as permeates in the transport experiments. Up to 40 fold higher pore fluxes were achieved with unmodified silicon nitride membranes relative to thicker commercial nanoporous membranes. Similarly, in mixed protein experiments, ∼5.0 and 1.9 fold higher BSA and BHb selectivities were obtained with fabricated thin membranes at pH 4.7 and 7.0, respectively, relative to the commercial nanoporous membranes.

Protein diffusion through charged nanopores with different radii at low ionic strength

“…Inorganic membranes based on aluminum anodic oxide and silica films incorporate micro-arrays of pores that have lower thicknesses than many commercial polymer membranes. 3 The different characteristics of these membranes have recently been reviewed. 8 To better understand the electrostatic interactions between protein and membrane, we have studied here the effect of pH and pore size on the diffusive transport of BHb and BSA through non-modified PCTE membranes with different pore radii at low ionic strength.…”

“…Protein diffusion through nanoporous membranes is affected by a multitude of parameters such as osmotic pressure, 1 electric field, 2 membrane thickness, 3 protein size (molecular weight), pore diameter, protein electrostatic charge and concentration, 4 charge distribution and shape of the protein, pore shape and functional groups on the pore surface, ionic strength, 5 pH, and temperature. In principle, the combination of these parameters may provide tools to control the transport of the protein.…”

Molecular Dynamics and Monte Carlo simulations resolve apparent diffusion rate differences for proteins confined in nanochannels

“…[1][2][3][4][5][6][7][8][9] Many recent studies have examined the transport of proteins and other molecules near surfaces and in confined geometries. [10][11][12][13][14][15][16][17][18][19][20][21] For example, lysozyme adsorption to charged surfaces was investigated using Monte Carlo (MC) by Carlsson et al, and it was found that adsorption was favoured by high protein concentration and high protein net charge, among other conditions.…”

“…Number of steps to cross boundary, average = 32 (b) route time, average = 0.008 s (c) path schematic for 20 and 1000 molecules 3. ; Nsurf/Nbulk = 4.0×10 4 ; fch = 0.59; Psurf =0.05.…”

Fabrication of functional silicon-based nanoporous membranes

“…Additional transport results are analyzed in detail elsewhere. 47,48 Pore selectivity may be improved by chemically modifying pore surfaces. For example, gold deposition on the membrane surface followed by attachment of self-assembled monolayers (SAM) has been shown to dramatically improve the membrane selectivity by promoting the control over the electrostatic interactions.…”