DFT investigation of temozolomide drug delivery by pure and boron doped C24 fullerene-like nanocages

Abstract

In this paper, the DFT/M05-2X-D3/6-31+G(d,p) theoretical chemistry method is used to probe the adsorption ability of pure and boron doped C₂₄ toward the temozolomide (TMZ) anticancer drug. The study is conducted in both gas and aqueous phases. The positive values of the Gibbs free energy of formation (12.03, 9.14 and 2.51 kcal mol⁻¹) show that the adsorption of TMZ on C₂₄ is not allowed. However, the boron-doped C₂₄ (BC₂₃) forms a very stable molecular complex with TMZ in the gas phase, characterized by the adsorption energy and Gibbs free energy values of −32.07 and −21.27 kcal mol⁻¹ respectively. Analysis of Hirshfeld's atomic charge revealed the transfer of 0.6395e from TMZ to BC₂₃, which is confirmed by the value of the dipole moment of the complex (13.42 D in the gas phase) as well as its molecular electrostatic potential map. The change in the frontier molecular orbital energy difference of BC₂₃ is found to be 21.67% proving the good sensitivity of the cage toward the drug. The TMZ–BC₂₃ molecular complex is very stable in water though the sensitivity of the cage is hugely reduced in that solvent. The reliability of these results was confirmed by checking the outcomes at both wB97XD/6-31+G(d,p) and B3LYP-D3/6-31+G(d,p) levels. This work shows that pristine BC₂₃ is a better adsorbent of TMZ than some reported nanomaterials from the theoretical chemistry point of view.