Chemical and physical modification of layer-by-layer assembled nanofilms composed of block copolymer micelles and graphene oxide for controlled drug release

In this study, multilayer films with two components, block copolymer micelles (BCM) and graphene oxide were prepared. To adjust the ratio of the model drugs (coumarin-6) loaded in the BCMs, we used BCM at pH values of 5.5 and 8.5. However, the release behavior of a model drugs was rapid, and most of drugs was released within 24 h. Therefore, to control the release rate of the drugs, we used two methods to modify the films: chemical modification of the inner structure and modification of the external structure. These two modifications were achieved by crosslinking and the addition of external layers, respectively, and we investigated the effects of these modifications on the release of the model drug. We observed a slow release profile, from 24 to almost 70 h, in the film modified with an external layer. In contrast, the crosslinked film showed different release profile that was dependent on the pH of the BCMs in the film. When the pH of the BCMs in the film was 5.5, the release of the drug was rapid, more so than the unmodified film. When the pH of the BCM in the film was 8.5, the drug release was similar to that of the unmodified film.