Self-Assembly of Polyoxometalate–Peptide Hybrids in Solution: Elucidating the Contributions of Multiple Possible Driving Forces

Abstract

Incorporating the building blocks of nature (e.g., peptides and DNA) into inorganic polyoxometalate (POM) clusters is a promising approach to improve the compatibilities of POMs in biological fields. To extend their biological applications, it is necessary to understand the importance of different non-covalent interactions during self-organization. A series of Anderson POM–peptide hybrids have been used as a simple model to demonstrate the role of different interactions in POM–peptide (biomolecules) systems. Regardless of peptide chain length, these hybrids follow similar solution behaviors, forming hollow, spherical supramolecular structures in acetonitrile/water mixed solvents. The incorporation of peptide tails introduces interesting stimuli-responsive properties to temperature, hybrid concentration, solvent polarity and ionic strength. Unlike the typical bilayer amphiphilic vesicles, they are found to follow the blackberry-type assemblies of hydrophilic macroions, which are regulated by electrostatic interaction and hydrogen bonding. The formation of electrostatic assemblies before the supramolecular formation is confirmed by ion-mobility mass spectrometry (IMS-MS).