Hypoxia, the typical and conspicuous characteristic of most solid
tumors, worsens the
tumor invasiveness and
metastasis. Here, we engineered a sequential ultrasound (US)/
hypoxia-sensitive sonochemotherapeutic nanoprodrug by initially synthesizing the
hypoxia-activated azo bond-containing
camptothecin (
CPT)
prodrug (CPT2-Azo) and then immobilizing it into the mesopores of sonosensitizer-integrated
metal organic frameworks (MOF NPs). Upon entering the hypoxic tumor microenvironment (TME), the structure of CPT2-Azo immobilized MOFs (denoted as MCA) was ruptured and the loaded nontoxic CPT2-Azo
prodrug was released from the MOF NPs. Under US actuation, this sonochemotherapeutic nanoprodrug not only promoted sonosensitizer-mediated sonodynamic
therapy (SDT) via the conversion of
oxygen into cytotoxic
reactive oxygen species (ROS) but also aggravated
hypoxia in the TME by elevating oxygen consumption. The exacerbated
hypoxia in turn served as a positive amplifier to boost the activation of CPT2-Azo, and the controllable release of toxic chemotherapeutic drug (
CPT), and compensated the insufficient treatment efficacy of SDT. In vitro and in vivo evaluations confirmed that sequential SDT and tumor hypoxia-activated sonochemotherapy promoted the utmost of tumor hypoxia and thereby contributed to the augmented antitumor efficacy, resulting in conspicuous apoptotic cell death and noteworthy
tumor suppression in vivo. Our work provides a distinctive insight into the exploitation of the
hypoxia-activated sonochemotherapeutic nanoprodrug that utilizes the hypoxic condition in TME, a side effect of SDT, to initiate
chemotherapy, thus causing a significantly augmented treatment outcome compared to conventional SDT.