ATP-responsive hollow nanocapsules for DOX/GOx delivery to enable tumor inhibition with suppressed P-glycoprotein

Multidrug resistance (MDR) restricts chemotherapy efficacy due to P-glycoprotein (P-gp) mediated drug efflux, whereas current approaches to suppressing P-gp expression suffer from intrinsic challenges, such as low transfection, high toxicity and poor specificity. Here, hollow ferric-tannic acid complex nanocapsules (HFe-TA), which can be effectively degraded by the reaction with adenosine triphosphate (ATP), are synthesized for the delivery of glucose oxidase (GOx) and doxorubicin (DOX) for tumor treatment. The findings indicate that the intracellular ATP is significantly decreased due to the combined effect of HFe-TA degradation and GOx-mediated glucose consumption. Along with this ATP down-regulation, P-gp expression of tumor cells is suppressed remarkably, which in turn promotes the intracellular accumulation and anticancer efficacy of DOX. In addition, the production of •OH by Fe ions released from HFe-TA is promoted by the by-products of the oxidation of glucose process by GOx. In consequence, HFe-TA nanocapsules loaded with DOX and GOx enable significant inhibition effect to tumors both in vitro and in vivo due to the synergistic effect of cascade reactions. This study has therefore provided an alternative therapeutic platform for effective tumor inhibition with the potential in overcoming intrinsic MDR.