A simple electroanalysis of polyG RNA in mixtures with 3',5'-cyclic guanosine monophosphate achieved by selective desorption of the monomers from the electrode surface

Previously it has been shown that cyclic nucleoside monophosphates can spontaneously polymerize to form RNA oligonucleotides under conditions simulating prebiotic conditions on Archean Earth. The most efficient polymerization was documented with 3',5'-cyclic guanosine monophosphate (cGMP). In this work a method for fast detection of short polyG RNAs present in a large overabundance of cGMP, modeling conditions in the non-enzymatic nucleotide polymerization mixtures, is presented. The method is based on electrochemical measurements of guanine (G) oxidation signals yielded by RNA oligomers adsorbed onto the surface of a pyrolytic graphite electrode (PGE). To avoid false positive results arising from the G oxidation signals due to coadsorbed cGMP, a method for selective removal of the monomers from the electrode surface has been devised. In the first step, both cGMP and RNAs are co-adsorbed onto the PGE surface. In the second step, the cGMP is selectively desorbed using treatments in solutions of different tested surfactants (SDS, Tween 20 or Triton X100), or by washing in deionized water at elevated temperature. We show that this new approach is suitable for selective analysis of products of polymerization reactions from mixtures of their building blocks.

Automated summary

This study introduces a fast detection method for RNA polymerization products by measuring the oxidation signals of RNA on an electrode surface. By selectively desorbing the co-adsorbed cGMP using different surfactant solutions or elevated temperature water washing, the method allows for the selective analysis of polymerization products from mixtures.