A theoretical quest for laetrile drug delivery by neutral, cationic, and anionic gold nanoparticles

Interactions of laetrile (D-mandelonitrile-(3-glucuronide, 1) with neutral (Au3), cationic (Au3+), and anionic (Au3-) gold nanoparticles are studied by the density functional theory (B3LYP/6-311++G(d,p) boolean OR LANL2DZ). Interaction of 1 and gold trimer nanoparticles occur between the Au atom and the O, N, and C atoms of 1, or through the unconventional Au...H-O hydrogen bonding. Depending on the charge on the gold nanoparticle, these bonds may contribute differently to the formation of the complex. Binding energy calculations indicate that the neutral Au nanoparticles have the lowest, while cationic Au3 + nanoparticles have the highest affinity for interaction with 1. Natural population analysis and charge transfers in the complexes are assessed by the natural bond orbital (NBO). Quantum theory of atoms in molecules (QTAIM) is also applied to interpret the nature of the bonding interactions.