Twins-like nanodrugs synchronously transport in blood and coalesce inside tumors for sensitive ultrasound imaging and triggerable penetrative drug delivery

Nanodrugs capable of aggregating in the tumor microenvironment (TME) have demonstrated great efficiency in improving the therapeutic outcome. Among various approaches, the strategy utilizing electrostatic interaction as a driving force to achieve intratumor aggregation of nanodrugs has attracted great attention. However, the great difference between the two nanodrugs with varied physicochemical properties makes their synchronous transport in blood circulation and equal-opportunity tumor uptake impossible, which significantly detracts from the beneficial effects of nanodrug aggregation inside tumors. We herein propose a new strategy to construct a pair of extremely similar nanodrugs, referred to as “twins-like nanodrugs (TLNs)”, which have identical physicochemical properties including the same morphology, size, and electroneutrality to render them the same blood circulation time and tumor entrance. The 1:1 mixture of TLNs (TLNs-Mix) intravenously injected into a mouse model efficiently accumulates in tumor sites and then transfers to oppositely charged nanodrugs for electrostatic interaction-driven coalescence via responding to matrix metalloproteinase-2 (MMP-2) enriched in tumor. In addition to enhanced tumor retention, the thus-formed micron-sized aggregates show high echo intensity essential for ultrasound imaging as well as ultrasound-triggered penetrative drug delivery. Owing to their distinctive features, the TLNs-Mix carrying sonosensitizer, immune adjuvant, and ultrasound contrast agent exert potent sonodynamic immunotherapy against hypovascular hepatoma, demonstrating their great potential in treating solid malignancies.