Improved manufacture of hybrid membranes with bionanopore adapters capable of self-luting

Abstract

The authors’ recent concept of bioinorganic filtration devices made up of solid-state membranes (SSMs) accommodating ring-shaped, ribonucleic acid (RNA)-stabilized tobacco mosaic virus (TMV) coat protein (CP) assemblies with central 4 nm holes as genetically encoded ‘pore-in-pore’ fittings, to convey size and charge specificity to the membranes’ permeability, has been elaborated. Key developments for simplifying and finishing the unique combination apply to both soft- and hard-matter components: previous SSMs with millions of conical pores demanded sophisticated lithography to achieve a taper trapping the bionanopores upon insertion in a flow. Now focused helium (He) ion beam technology has enabled efficient, fast preparation of silicon nitride templates adapted to the nanorings. Proof-of-concept experiments reveal that negative charges imparted by nucleic acids exposed on the bionanopores might improve electrophoretic implantation further. Suitable peptides installed on the outer nanoring rim had been shown to nucleate spatially confined silica deposition from liquid precursors, which have been optimized in order to seal the annular gaps between bio and inorganic SSM pores by ‘bionic glue’. Finally, two engineered CP variants and a modified scaffold RNA were established for novel TMV nanoring types with altered pore charges, which also allow installing accessory molecules for advanced filtration and conversion tasks.

From stars to stripes: RNA‐directed shaping of plant viral protein templates—structural synthetic virology for smart biohybrid nanostructures

“…Moreover, mineralization‐guiding peptides installed on the outer nanoring rim were shown to induce a site‐specific silica deposition around the bionanostructure from liquid precursors (Lemloh, Altintoprak, Wege, Weiss, & Rothenstein, ), which may serve as “bionic glue” to immobilize the nanoporous assemblies for example, in solid state membranes (Farajollahi et al, ). On this basis, a novel concept for using bionanopores with genetically engineerable selective permeability in technical environments has been proposed, for a charge‐ and size‐discriminating detection or specific separation of molecules by help of robust pore‐in‐pore layouts (Altintoprak et al, ). It should be added here, however, that in parallel to the RNA‐stabilized nanorings with superior pH stability and dispersal, also a number of engineered TMV CP types have been developed that allow the fabrication of similarly robust disks devoid of RNA, due to enhanced CP‐CP interactions (Bruckman et al, ; Dedeo et al, ; Finbloom et al, ; J. Zhang, Wang, Zhou, Chen, & Wang, ; J. Zhang, Zhou, & Wang, ; Zhou, Li, Dai, Meng, & Wang, ).…”

Protein Nanopore Membranes Prepared by a Simple Langmuir–Schaefer Approach

“…It should also be mentioned that membrane preparation based on lipid or block copolymer bilayers is solely suited for TPs and, so far, the incorporation of other interesting biological nanopores, such as virus-like particles derived from tobacco mosaic virus (TMV), [25] into stable membranes has required rather cumbersome procedures. [26,27] To bypass these limitations, we pursue different strategies of membrane fabrication that provide covalent stabilization and dense arrangement of protein nanopores. Previously, we crosslinked ferritin-polymer conjugates to ultrathin membranes and formed nanopores by denaturation of the protein.…”