Polyoxometallate ions as models for mineral nanoparticle interactions with proteins: insight into structure and reactivity

Mineral nanoparticles (NPs) form naturally by weathering of rock, and artificially by industry. They are abundant in our surroundings, so it is important to know what the effects on living organisms might be. NPs often interact with proteins, important building blocks and biocatalysts in all living things. The potential effects of NPs on proteins could be either detrimental or beneficial, and it is important to know which. Using a model system, we have identified a number of factors which can affect how NPs interact with biomolecules. These are: 1) the polarity of the metal-oxide bond, as determined by the metal atom’s electronegativity; 2) the hydrophobicity of the ligand, determined in our model by the length of an oligoglycine; 3) the ionic strength of the solution, as cations in excess will compete for binding spots with the ligand, replacing it on the NP surface; 4) The shape of the ligand, as demonstrated by structure determining peptides; 5) The relative affinity of ligands, as shown by one NP readily crystallizing with a buffer molecule rather than a peptide, but not interacting noticeably with a similar buffer. Certain NPs are unstable under specific conditions, such as pH, while others tolerate it, and complexes with ligands can differ for these NPs. In addition, compounds used in the model were used as a model in a study on antiviral activity, and were also used to produce a Sol-Gel material with remarkable efficacy in electrocatalytic water splitting.