Hierarchically structured emulsions for brain therapy

Abstract In this paper, we developed a doxorubicin-loaded double emulsion, with a specific pH-triggered drug release mechanism, and with functionalized drops’ surfaces as an effective drug (doxorubicin-DOX) delivery implant for brain tumor therapy. The functionalization of double emulsions with antibodies at oil-water interfaces was performed for targeting brain tumor cells - glioblastoma multiforme (GBM). The functionalization involved physical adsorption of antibodies: anti-CD15 (GBM-targeting surface proteins) on oil drops of double water-in-oil-in-water emulsions. The interactions between molecules of antibodies and compounds of the oil drops were measured using isothermal titration calorimetry (ITC). Double emulsions with different structures and pH-sensitive polymer (sodium carboxymethylcellulose) in the external phase were prepared by a one-step method, in a Couette-Taylor flow contactor. The release rates of DOX from emulsions were analysed in phosphate buffers with a pH of 6.3 (acidic microenvironment of solid tumors) and a pH of 7.4 (normal cells). The release study demonstrated an expected morphology/structure, composition and pH-responsive controlled release behaviour. The ITC analysis showed that antibodies interacted with emulsion compounds, which was vital for functionalization of drops of emulsion for targeting cancer cells. This was demonstrated by changes in the heat rates reflecting molecular interactions and proved that proteins adhered to oil-drop interfaces.