Background: Challenges such as poor drug selectivity, non-target reactivity, and the development of drug resistance continue to pose significant obstacles in the clinical application of cancer therapeutic drugs. To overcome the limitations of drug resistance in chemotherapy, a viable treatment strategy involves designing multifunctional nano-platforms that exploit the unique physicochemical properties of tumor microenvironment (TME). Methods: Herein, layer-by-layer nanoparticles with polyporous CuS as delivery vehicles, loaded with a sonosensitizer (tetra-(4-aminophenyl) porphyrin, TAPP) and sequentially functionalized with pH‐responsive CaCO 3 , targeting group hyaluronic acid (HA) were designed and synthesized for synergistic treatment involving chemodynamic therapy (CDT), sonodynamic therapy (SDT), photothermal therapy (PTT), and calcium overload. Upon cleavage in an acidic environment, CaCO 3 nanoparticles released TAPP and Ca 2+ , with TAPP generating 1 O 2 under ultrasound trigger. Exposed CuS produced highly cytotoxic ·OH in response to H 2 O 2 and also exhibited a strong PTT effect. Results: CuS@TAPP-CaCO 3 /HA (CTCH) delivered an enhanced ability to release more Ca 2+ under acidic conditions with a pH value of 6.5, which in situ causes damage to HeLa mitochondria. In vitro and in vivo experiments both demonstrated that mitochondrial dysfunction greatly amplified the damage caused by reactive oxygen species (ROS) to tumor, which strongly confirms the synergistic effect between calcium overload and reactive oxygen therapy. Conclusion: Collectively, the development of CTCH presents a novel therapeutic strategy for tumor treatment by effectively responding to the acidic TME, thus holding significant clinical implications. Keywords: mitochondria damage, calcium overload, reactive oxygen oncotherapy, pH-responsive, synergistic treatment

Layer-by-Layer Nanoparticles for Calcium Overload in situ Enhanced Reactive Oxygen Oncotherapy