Transfer RNAs (tRNAs) are small, stable, L-shaped RNA molecules that transfer amino acids to the growing polypeptide chain dur-ing protein synthesis. Exploiting the similarity in shape between tRNA and H₂O molecules, our aim has been to produce a tRNA build-ing block that will self-assemble into higher aggregates, with a goal of 3D arrays, for possible application as molecular sieves or scaolds. Some tRNAs can form dimers by intermolecular base-pairing of their single-stranded loops. The glycine tRNA (GCC) gene fromEsch-erichia coliwith additional complementarity in a specic loop (T loop). Initial aggregation studies showed two of ve variant tRNAs tested formdimers at neutral pH in the presence of spermine and magnesium and sodium chloride ions, in contrast to the starting tRNA. One formsdimers rapidly, the other more slowly, possibly due to the need for structural rearrangement to disruptintramolecular interactions beforedimerization can occur. Surprisingly, with the variant where arrays were possible there was a lack of higher aggregates, which may be dueto steric hindrance around the elbow region formed from the 3D folding of this tRNA.