Water serves as a stable and an inert solvent for many organic, inorganic, and biological reactions. However, we have shown that pure water can exhibit catalytic activities when it is formed into microdroplets. We have shown that reaction rates for various chemical and biochemical reactions, including protein unfolding, protein-ligand interactions, hydrogen/deuterium exchange, chlorophyll demetallation, and addition/condensation reactions, are accelerated by 103 to 106-fold in microdroplets compared with bulk solution (PNAS, 2015; Q Rev Biophys, 2015; and Q Rev Biophys, 2017). We also have shown that the chemical reactions such as phosphorylation of various sugars and condensation reactions for RNA synthesis that has positive Gibbs free energy change in bulk solution can proceed spontaneously in aqueous microdroplets without any catalyst or an external energy source (PNAS, 2017 and 2018). The spontaneous phosphorylation and condensation reaction in microdroplets occurred by overcoming the entropic hurdle of the reaction encountered in bulk solution. In addition, we found that the redox reactions for various molecules including pyruvate, lipoic acid, fumarate, NADH, and NADPH can occur without any added reducing or oxidizing agent or externally applied charge. This catalytic behaviors are considered to originate from the unique properties of air-water interface, including adsorption of molecules to the water surface, local pH shift, molecular organization and alignment of reactants, and intrinsic strong electric field at the air-water interface. This microdroplet chemistry shows that the water itself can serve as a catalyst for various reactions.

Water microdroplets catalyze chemical reactions

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.