Tailoring the interlayer interaction between doxorubicin-loaded graphene oxide nanosheets by controlling the drug content

We experimentally and theoretically investigated the influence of a model drug, doxorubicin (DOX) on GO interlayer interaction by evaluating the pyrolysis activation energy using thermogravimetric analysis and a mathematical model. It was found that the pyrolysis activation energy of DOX-loaded GO decreased from 145.8 to 119.5 kJ/mol with DOX loading content increasing from 0 to 186.6 w/w%. Theoretical simulation showed that the reduced activation energy could be ascribed to the gradually decreased interlayer interaction with DOX molecule intercalation. This involved distorted π–π stacking originating from the enlarged interlayer distance, and partially blocked interlayer hydrogen bonding. Our study suggested the possibility of tailoring the interlayer interaction and macroscopic properties of GO composites by controlling the density of molecules on the individual sheet, and offered a better understanding of inserted molecules causing interlayer interaction changes.