Abstract

Our recent concept of bio/inorganic filtration devices made up of solid-state membranes (SSMs) accommodating ring-shaped, 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 for sophisticated lithography to achieve a taper trapping the nanoporous bio-‘disks’ upon insertion in a flow. Now focused He ion beam technology has enabled an 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 bio-pores might improve electrophoretic implantation further. Suitable peptides installed on the outer bio-nanopore rim had been shown to nucleate spatially confined silica deposition from liquid precursors, which has 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.

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