Hamaker constants of materials at the bionano interface reveal nanotoxicity and biological activity/drug delivery preference

Hamaker energies appear as a dominant contribution to the total interactions at the bionano interface in water. Among the electrostatic interactions where charged units (amino acids) of proteins attract water and the charged nanoparticle surface, the dispersion interaction becomes more and more dominant as the size of the proteins/lipids and nanoparticles increases. A large number of proteins and lipids, about 50, and nanomaterials (metals, metal oxides, polymers, carbon nanotubes, graphene) also about 50 have been evaluated for this scope.

We understand that the underlying pairwise contributions of the parts (nanoparticle, protein, water) of the whole system (nanoparticle/nanoparticle, nanoparticle/water, nanoparticle/protein, protein/protein, protein/water, water/water) can be attractive or repulsive and therefore we analyse all the contributions in detail. Finally, we argue why the total contribution appears positive or negative in comparison to measured Hamaker constants data, where experimental data are available, and how the pairwise interaction approach could affect the real interaction of the parts in the whole system and on the real conditions interactions of the nanoparticles in the human organism and environment. 

Conclusively we remark on the correlation to biological activity of nanomaterials. A database with amino acid and lipid fragments adsorption strengths has been created and from the procentual abundance of the respective amino acids and lipid fragments in proteins and lipids the biological activity of nanomaterials is estimated. Notably, that the calculated Hamaker constants for nanomaterials in water correlate nicely with hydrophobicity/hydrophilicity parameters, i.e., immersion enthalpies of spherical nanoparticles in water obtained with the same force field parameters (CHARMM) which account for dispersion only. Moreover, the calculated Hamaker constants for biomolecules at a nanoparticle surface in water, i.e., amino acids and lipid fragments agree well with the potential of mean forces of the same amino acids and lipid fragments immersed in water near a nanoparticle surface. Bond breaking potentials, i.e., reactive potentials on the other hand show a different ranking of interaction strengths between the biomolecules and the nanomaterials in water.