Molecular dynamics simulation of the adsorption behavior of two different drugs on hydroxyapatite and Zn-doped hydroxyapatite.

Hydroxyapatite (HAp) is a highly promising material as a drug carrier. The solubility, osteoinductivity, antibacterial properties and drug loading efficiency of HAp can be further enhanced by Zn doping. In this study, we carried out first-principles and molecular dynamics (MD) simulations to investigate the influence of Zn doping on the crystal structure and adsorption capacity of macromolecular drugs on HAp. Our results showed that the binding energy of doxorubicin (DOX) on HAp is significantly increased in consequence of Zn-doping. Moreover, the interaction between surface Ca ions and carbonyl-O mostly contributed to the adsorption. The binding energy of tinidazole on HAp was much lower than that observed for DOX. The number of active "O" atoms in the drug and binding stability were positively correlated. These simulations provide important insight into the understanding of drug adsorption on HAp or ion-doped HAp.