The effects of surface charge on the intra-tumor penetration of drug delivery vehicles with tumor progression

The limited penetration of drug delivery vehicles in tumors reduces their therapeutic efficacy, which is a major obstacle. Thus, great efforts have already been paid to regulate both tumor tissue and the physicochemical properties of drug delivery vehicles to achieve deeper penetration. However, the principles for regulating these properties remain unclear. Herein, we investigated the performance of nanocapsules in different tumor stages, and particularly focused on the difference in the performance of nanocapsules with different surface charges. Our in vivo and in vitro results showed that when the tumor was small in the early stage, the electropositive nanocapsules could penetrate much deeper than the electronegative nanocapsules; however, when the tumor was quite large in the late stage, the electronegative nanocapsules would penetrate further into the tissue. This study proposes a potential strategy for tumor therapy by selecting drug delivery vehicles with an appropriate surface charge based on the tumor development stages.