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Rapid fabrication of precise high-throughput filters from membrane protein nanosheets

Abstract

Biological membranes are ideal for separations as they provide high permeability while maintaining high solute selectivity due to the presence of specialized membrane protein (MP) channels. However, successful integration of MPs into manufactured membranes has remained a significant challenge. Here, we demonstrate a two-hour organic solvent method to develop 2D crystals and nanosheets of highly packed pore-forming MPs in block copolymers (BCPs). We then integrate these hybrid materials into scalable MP-BCP biomimetic membranes. These MP-BCP nanosheet membranes maintain the molecular selectivity of the three types of β-barrel MP channels used, with pore sizes of 0.8 nm, 1.3 nm, and 1.5 nm. These biomimetic membranes demonstrate water permeability that is 20–1,000 times greater than that of commercial membranes and 1.5–45 times greater than that of the latest research membranes with comparable molecular exclusion ratings. This approach could provide high performance alternatives in the challenging sub-nanometre to few-nanometre size range.

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Fig. 1: Stable β-barrel MP-BCP-based scalable membranes.
Fig. 2: 2D crystals or nanosheets of three β-barrel channel proteins reconstituted in BCP membrane matrices.
Fig. 3: 2D OmpF nanosheets can be assembled on a PC (50 nm), PES (MP005) or aluminium oxide (0.02 μm Anodisc) substrate.
Fig. 4: Three scalable biomimetic membranes based on β-barrel channel MPs and BCPs demonstrate distinct molecular separations and enhanced pure-water permeability compared with current commercial membranes.
Fig. 5: Comparison of water permeability (LMH bar–1) and MWCO (Da) of MP-based membranes with commercial NF or ultrafiltration membranes tested in the same experimental setup.

Data availability

The data supporting the findings of this study are available within the article and its supplementary information files and available from the authors upon reasonable request.

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Acknowledgements

The authors acknowledge financial support from the National Science Foundation (NSF) CAREER grant (CBET-1552571), NSF grant CBET-1709522 and NSF grant CBET-1804836 to M.K. for this work. T.C. and E.D.G. acknowledge financial support from NSF DMR-1609417. The authors also thank M. Hazen and J. Cantolina for their help with cross-sectional sample preparation. We thank L. Movileanu for the kind gift of the plasmid for expressing the FhuA ΔC/Δ4L protein.

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Y.-M.T., W.S., T.R. and M.K. conceived and designed the research. T.R., W.S., Y.-M.T., Y.-x.S. P.R., T.E.C. and L.S. performed the experiments, with the assistance of R.C., C.L., A.T., D.C., Y.D., A.M. and M.Z. in specialized analytic tools. T.R., Y.-M.T., P.R., A.P., J.N.S., S.H.M. and M.G. contributed to the protein production. Y.-M.T., W.S., T.R., R.C., T.E.C., L.S., D.B., W.A.P., E.D.G., R.J.H., Y.W. and M.K. analysed and interpreted the data and results. T.R., W.S., Y.-M.T. and M.K. co-wrote the paper.

Corresponding author

Correspondence to Manish Kumar.

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A.P. and M.G. are employed by Applied Biomimetic, which aims to commercialize biomimetic membranes similar to those presented in this Article.

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Supplementary discussion, Tables 1–5, Figures 1–19, references 1–31.

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Tu, YM., Song, W., Ren, T. et al. Rapid fabrication of precise high-throughput filters from membrane protein nanosheets. Nat. Mater. 19, 347–354 (2020). https://doi.org/10.1038/s41563-019-0577-z

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