DFT study of SiO2 nanoparticles as a drug delivery system: structural and mechanistic aspects

Adsorption and reaction mechanisms for the noncovalent and covalent functionalization of SiO2 nanoparticle (SiNP) with gemcitabine (GEM) anticancer drug have been investigated, respectively. Electronic and structural properties have been studied in an aqueous environment at M06-2X/6-31g(d,p). The energetic stability of five noncovalent configurations (SiNP/GEM1–5) was confirmed by the calculation of binding energies. Since the solubility of the drug and SiNP increases in SiNP/GEM1-5, the SiO2 nanoparticle could be used as an appropriate drug delivery system. Quantum molecular descriptors indicated that the reactivity of SiNP increases in SiNP/GEM1–5. The AIM analysis for noncovalent configurations demonstrated that the intermolecular hydrogen bonds play important roles in this system. The possibility of chemical bond formation between SiNP and GEM has been investigated through NH2 (NH2 mechanism), CH2OH (CH2OH mechanism), and OH (OH mechanism) groups. The calculation of the activation parameters showed that the hydroxymethyl pathway is spontaneous and exothermic and has a lower activation energy.