An electrosensitive peptide probe has been developed from an in vitro selection technique using biorthogonal tRNA prepared with an electroreactive non-natural amino acid, 3,4-ethylenedioxythiophene-conjugated aminophenylalanine. The selected probe quantitatively detected the influenza virus based on a signal "turn-on" mechanism. The developed strategy could be used to develop electrochemical biosensors toward a variety of targets.

One of the most powerful attributes of proteins is their ability to bind to and modulate the chemistry of cofactors and prosthetic groups. Here, we demonstrated the ability of an artificial nucleic acid (an aptamer) to similarly control the functionality of a non-biological element. Specifically, we selected an RNA aptamer that binds tris(bipyridine) ruthenium (II), Ru(bpy)32+, an inorganic complex that has attracted intense interest due to its photoredox chemistry, including its ability to split water by visible light. We found that a newly discovered aptamer strongly and enantioselectively binds Λ-Ru(bpy)32+ (Kd = 65 nM) and, in doing so, selectively suppresses deactivation via energy transfer, thereby elongating the lifetime of its photo-excited state by four-fold. The ability of the aptamer to enhance this important aspect of Ru(bpy)32+ chemistry illustrates a broader point concerning the potential power of combining in vitro-created biomolecules with non-biological reactants to perform enhanced chemical reactions.

Correction for 'In vitro selection of electrochemical peptide probes using bioorthogonal tRNA for influenza virus detection' by Tara Bahadur K. C. et al., Chem. Commun., 2018, 54, 5201-5204.

In vitro selection has been widely used to generate molecular recognition elements in analytical sciences. Although reconstituted types of in vitro transcription and translation (IVTT) system, such as PURE system, are nowadays widely used for ribosome display and mRNA/cDNA display, utilizing E.coli extract tends to be avoided presumably because it contains unfavorable contaminants such as ribonuclease. Nevertheless, the initial speed of protein translation in E.coli extract is markedly faster than that of PURE system. Thus, we hypothesized that E.coli extract is more appropriate for instant translation in ribosome display than PURE system. Here, we first revisit the potency of E. coli extract for ribosome display by shortening the translation time and then applied the optimized condition to the selection of peptide aptamers for ovalbumin (OVA). The OVA-binding peptides selected using E.coli extract exhibited specific binding to OVA even in the presence of 50% serum. We conclude that instant translation in ribosome display using E.coli extract has the potential to be used to generate easy-to-use and economical molecular recognition elements in analytical sciences.