New Strategies in the Design of Nanomedicines to Oppose Uptake by the Mononuclear Phagocyte System and Enhance Cancer Therapeutic Efficacy

The application of nanotechnology in the treatment of tumors has boomed owing to the vigorous development in cancer nanomedicine. Despite the great success achieved in this field, nanomedicine has not realized its full potential owing to a delivery barrier, the mononuclear phagocytic system (MPS), which cuts off more than 95 % of the administrated nanoparticles. This results in an extremely low drug-delivery efficacy to the tumor and leads to poor therapeutic outcomes. Moreover, the injection of excess nanoparticles also raises toxicity concerns induced by the accumulation of nanomaterials in organs, such as the liver and spleen. Therefore, a reduction in the uptake of nanomedicines by the MPS is vital to enhance the cancer therapeutic effect and decrease side effects. In this critical review, we will summarize the new strategies to reduce nanoparticle uptake by the MPS based on current knowledge of the bio-nano interaction. Further directions will also be highlighted for the development of cancer nanomedicine with a lower off-target rate and better therapeutic outcomes.