An In Silico study of TiO2 nanoparticles interaction with twenty standard amino acids in aqueous solution

Abstract

Titanium dioxide (TiO2) is probably one of the most widely used nanomaterials, and its extensive exposure may result in potentially adverse biological effects. Yet, the underlying mechanisms of interaction involving TiO2 NPs and macromolecules, e.g., proteins, are still not well understood. Here, we perform all-atom molecular dynamics simulations to investigate the interactions between TiO2 NPs and the twenty standard amino acids in aqueous solution exploiting a newly developed TiO2 force field. We found that charged amino acids play a dominant role during the process of binding to the TiO2 surface, with both basic and acidic residues overwhelmingly preferred over the non-charged counterparts. By calculating the Potential Mean Force, we showed that Arg is prone to direct binding onto the NP surface, while Lys needs to overcome a ~2 kT free energy barrier. On the other hand, acidic residues tend to form “water bridges” between their sidechains and TiO2 surface, thus displaying an indirect binding. Moreover, the overall preferred positions and configurations of different residues are highly dependent on properties of the first and second solvation water. These molecular insights learned from this work might help with a better understanding of the interactions between biomolecules and nanomaterials.

Bionano Interactions: A Key to Mechanistic Understanding of Nanoparticle Toxicity

“…The largest negative figures come from the charged ARG, and large SER, TYR and TRP. These observations are in agreement with results of direct atomistic and ab initio simulations of AA and peptide adsorption on titania surfaces, which confirm that the adsorption is driven by charged residues [47][48][49]. We also note two other important features of the size dependence of the adsorption energy: the saturation at large NP radii, such that the limiting value corresponds to a flat surface, and the stronger binding at large radii due to the greater van der Waals attraction.…”

Impact of surface curvature, grafting density and solvent type on the PEGylation of titanium dioxide nanoparticles

“…The long-range effect of the TiO 2 nanoparticles surface on water has been already shown in other classical molecular dynamics study [54,56,84]. In particular, it has been reported in a recent publication by some of us [57], that the effect is propagated even to longer distances if a correct quantum chemical explicit description of the solvent, with a DFT-based method, is employed.…”

Nanoparticles as Potential Antivirals in Agriculture

“…In contrast, Lys needs to overcome a free energy barrier of 2 kT. Moreover, acid residues tend to form hydrogen bonds between their side chains and the TiO 2 surface, thus showing an indirect link [58].…”