Exploration on the adsorption mechanism of aminopyrimidines and quinazoline compounds on graphene oxide: Hydrophobicity and structure-controlled release process

In this study, graphene oxide was synthesized using the Hummers method, and stable and homogeneous graphene oxide aqueous solutions were obtained through mechanical stirring and ultrasonic stripping. In conjunction with our previous studies, graphene oxide-loaded insoluble compound delivery systems were prepared to verify the in vivo release profiles of the graphene oxide delivery system. Several insoluble compounds including imatinib, nilotinib, erlotinib, gefitinib, and afatinib were selected for loading and in vitro graphene oxide release assays to study the non-covalent adsorption mechanisms. Computer simulations were employed for validation processes. For in vivo release assays, the T-1/2 values of the poorly water soluble groups were 1.104 +/- 0.18 h and the C-max was 2.600 +/- 2.06 mg/L. In previous assays, compounds with high water solubility supported by graphene oxide were released and detected in vivo. The solubility of the compound and its binding force with the carrier played a crucial role in release. The results of graphene oxide loading experiments showed that the maximum loading and entrapment efficiencies of the insoluble model compounds with similar aromatic rings were comparable. Under basic conditions, the in vitro release rates and maximum release levels of amino pyrimidine were elevated. In contrast, quinazoline release declined. Combined with computer simulations, pi-pi stacking was identified as the dominant mechanism for adsorption onto graphene oxide. Both hydrogen bonding and cation-pi bonds played an auxiliary reinforcing role, and the two were regarded as antagonistic.