(729b) Highly Permeable and Selective Bioinspired Membranes Made By Membrane Protein 2D Crystals

Highly
permeable and selective bioinspired membranes made by membrane protein 2D
crystals

Yue-xiao Shen¹, Woochul Song¹, Siyi Qu²,
William A. Phillip², Manish Kumar¹

¹ Department
of Chemical Engineering, The Pennsylvania State University, University Park,
PA, 16802

² Department
of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame,
IN, 46556

Bioinspired
membranes functionalized with transport membrane proteins is an emerging
separation technology and has the potential advantages of high permeability and
exceptional selectivity of these biological channels. However, scale-up of this
technology has been hindered by the challenges of aligning membrane proteins
vertically, assembling them with high packing density, and sealing the
functional separating layer onto a porous support. Here, we utilized the
intrinsic property of some membrane proteins that can be packed as 2
dimensional crystals in lipids.¹
A bacterial porin, outer
membrane protein F (OmpF), is a beta barrel channel with a pore size of ~1 nm
(Fig. A). This protein was self-assembled into 2 dimensional crystals in poly(butadiene)-b-poly(ethylene
oxide) (PB₁₂-PEO₈) block copolymer membranes (Fig. B).² The carboxylic functionalized polymeric
2D materials was then assembled into a dense active layer on track-etched
polycarbonate membranes via layer-by-layer deposition. This separating layer
was further infiltrated with crosslinking reagents to enhance its integrity
(Fig. C and D). The resulting highly packed biological channel based composite
membranes could be used as nanofiltration membranes, and showed high water permeability
while maintaining selectivity superior to those reported in literature with
other approaches.

Figure.
A layer-by-layer self-assembly technique to fabricate 2D crystals based
membrane. (A) A negative-stain TEM image shows the lattice structure of outer
membrane protein F (OmpF)/ PB₁₂-PEO₈ 2D crystals (inset
shows the protein structure). (B) Schematic representation of the alternate
multilayers OmpF 2D crystals and polyethylenimine
deposited on track-etched membranes by layer-by-layer self-assembly. (C) An SEM
image shows a track-etched membrane has been covered with OmpF 2D crystal
sheets.

References

1          Scheuring,
S. et al. High resolution AFM
topographs of the Escherichia coli water channel aquaporin Z. EMBO J. 18, 4981-4987, (1999).

2          Klara,
S. S. et al. Magnetically Directed
Two-Dimensional Crystallization of OmpF Membrane Proteins in Block Copolymers. J. Am. Chem. Soc. 138, 28-31, (2016).