Oxygenated theranostic nanoplatforms with intracellular agglomeration behavior for improving the treatment efficacy of hypoxic tumors.

Hypoxia plays vital roles in the development of tumor resistance against typical anticancer therapies and local reoxygenation has proved effective to overcome the hypoxia-induced chemoresistance. Perfluorocarbon (PFC) is an FDA approved oxygen carrier and currently vigorously investigated for oxygen delivery to tumors. This study reports a perfluorocarbon and etoposide (EP) loaded porous hollow Fe3O4-based theranostic nanoplatform capable of delivering oxygen to solid tumors to enhance their susceptibility against EP. Results show that oxygen could be released at a moderate rate from the porous hollow magnetic Fe3O4 nanoparticles (PHMNPs) over an extended period of time, therefore effectively reducing the hypoxia-induced EP resistance of tumor cells. Moreover, the surface of PHMNPs was modified with lactobionic acid (LA)-containing amphiphilic polymers via hydrophobic interaction, which could provide targeting effect against certain types of tumors. The hydrophilic moiety would be subsequently shed by the intratumoral GSH after cellular internalization and result in the agglomeration of nanocarriers inside tumor cells, consequently impeding the nanoparticle exocytosis to enhance their intracellular retention. The enhanced retention could elevate the intracellular EP level and effectively boost the tumor cell killing effect. In addition to the therapeutic benefits, the Fe3O4 nanocage could also be used for the magnetic resonance imaging of the tumor area. The assorted benefits of the composite nanosystem are anticipated to be advantageous for the treatment of drug-resistant hypoxic tumors.