Chemical reactivity of the tryptophan/acetone/DMSO triad system and its potential applications in nanomaterial synthesis

Previously, we reported a novel browning reaction of amino acids and proteins in an organic solvent mixture composed of dimethyl sulfoxide (DMSO) and acetone. The reaction proceeds under surprisingly mild conditions, requiring no heating or additional reactants or catalysts. This present study aimed to investigate the chemical reactivity of the triad reaction system of l-tryptophan/aectone/DMSO. We demonstrated that, in DMSO, l-tryptophan initially catalyzed the self-aldol condensation of acetone, resulting in the formation of mesityl oxide (MO). Furthermore, we showed that the three-component system evolved into a diverse chemical space, producing various indole derivatives with aldehyde or ketone functional groups that exhibited self-assembling and nanoparticle-forming capabilities. We highlight the potential applications in nanomaterial synthesis.