DFT investigation on the application of a thiol-protected gold cluster Au12(SCH3)9+ toward adsorption of temozolomide

Abstract

The adsorption behavior of a thiol-protected gold cluster Au12(SCH3)9+ to temozolomide (TMZ) has been investigated at the M06-2X-D3/6-311G(d, p)&LanL2dz//B3LYP-D3(BJ)/6-31G(d,p)&LanL2dz. Results show that TMZ prefers to combine with the central Au atom in the Au cluster via its O and N atoms, forming ionic Au–O and Au–N bonds, respectively. The calculated adsorption energies of TMZ on Au12(SCH3)9+ are − 44.43, −12.27, −43.59, and − 10.01 kcal·mol−1 in the gas phase, water, acetic acid, and dimethyl sulfoxide, respectively. The interaction strength and mode between the TMZ drug and Au12(SCH3)9+ vary with different solution environments. Therefore, the solvent could influence the interaction of TMZ-Au12(SCH3)9+ complexes. Such a property of TMZ–Au12(SCH3)9+ could be applied to drug-delivery processes, which might contribute to improving the efficiency of this drug and reducing its toxic and side effects. Based on the natural population analysis and QTAIM analysis, noticeable charge transfer from TMZ to the Au cluster was observed, increasing the dipole moments of TMZ–Au12(SCH3)9+ complexes. We believe that this work could extend the applications of small Au-based clusters, especially thiol-protected gold clusters in drug-delivery processes.