In vitro selection of RNA sequences capable of mediating the formation of iron oxide nanoparticles

In vitro selection experiments involving RNA, phagemids, or whole cells can yield biomolecules that bind tightly to or mediate the formation of inorganic materials. Herein we show that RNA sequences that mediate the formation of metal oxide nanoparticles can be isolated from iterative cycles of RNA selection and amplification. In contrast to prior work, the in vitro selection described within was based upon a desired materials property. In order to be isolated from a starting random sequence pool, an RNA sequence was required to mediate the assembly of Co and/or Fe into a solid that responded to a magnetic field. Sequences isolated from this selection were able to mediate the formation of iron oxide nanoparticles containing small amounts of Co under atypical synthesis conditions of temperature and pH.