The effect of drug loading on micelle properties : solid-state NMR as a tool to gain structural insight

The present study highlights the importance of understanding the structural changes of micelles induced by drug loading on their physico-chemical properties. A block copolymer with attached fructose, which interacts with GLUT5 receptor, was used and conjugated with a low and a high amount of platinum drugs. Against expectations, the low-loading micelle, despite having a less defined morphology and larger nanoparticle size according to TEM, displays higher cellular uptake and higher toxicity. This behaviour can only be understood when elucidating additional information on the structure of micelles. Extensive solid-state NMR measurements were therefore employed to reveal that the drug loading affected swelling and mobility of core and shell of the micelle. The results obtained from solid-state NMR spectroscopy could explain all the observations on this system. In summary, solid-state NMR spectroscopy is an excellent tool to understand the effects of drug loading on the behavior of micelles.