Response to Comment on "A Liposomal System Capable of Generating CO2 Bubbles to Induce Transient Cavitation, Lysosomal Rupturing and Cell Necrosis"

pH-Regulating Nanoplatform for the "Double Channel Chase " of Tumor Cells by the Synergistic Cascade between Chlorine Treatment and Methionine-Depletion Starvation Therapy

During rapid proliferation and metabolism, tumor cells show a high dependence on methionine. The deficiency of methionine exhibits significant inhibition on tumor growth, which provides a potential therapeutic target in tumor therapy. Herein, ClO₂-loaded nanoparticles (fluvastatin sodium&metformin&bupivacaine&ClO₂@CaSiO₃@MnO₂-arginine-glycine-aspatic acid (RGD) (MFBC@CMR) NPs) were prepared for synergistic chlorine treatment and methionine-depletion starvation therapy. After outer layer MnO₂ was degraded in the high glutathione (GSH) tumor microenvironment (TME), MFBC@CMR NPs released metformin (Me) to target the mitochondria, thus interfering with the tricarboxylic acid (TCA) cycle and promoting the production of lactate. In addition, released fluvastatin sodium (Flu) by the NPs acted on monocarboxylic acid transporter 4 (MCT4) in the cell membrane to inhibit lactate leakage and induce a decrease of intracellular pH, further prompting the NPs to release chlorine dioxide (ClO₂), which then oxidized methionine, inhibited tumor growth, and produced large numbers of Cl^- in the cytoplasm. Cl^- could enter mitochondria through the voltage-dependent anion channel (VDAC) channel, which was opened by bupivacaine (Bup). The disruption of Cl^- homeostasis promotes mitochondrial damage and membrane potential decline, leading to the release of cytochrome C (Cyt-C) and apoptosis inducing factor (AIF) and further inducing cell apoptosis. To sum up, the pH-regulating and ClO₂-loaded MFBC@CMR nanoplatform can achieve cascade chlorine treatment and methionine-depletion starvation therapy toward tumor cells, which is of great significance for improving the clinical tumor treatment effect.

Explosible nanocapsules excited by pulsed microwaves for efficient thermoacoustic-chemo combination therapy

Microwave irradiation is a powerful non-invasive approach for treating deep-seated diseases in a clinical setting. Pulsed microwave-induced thermoacoustic cavitation allows precise cancer treatment with microwave-absorbing materials. This differs from the traditional continuous microwave-induced thermotherapy which may be harmful to off-target tissues. Here we first report the integration of thermocavitation and cytoplasmic drug release into highly explosible cell-penetrating nanocapsules for effective tumor inhibition under pulsed microwave irradiation. The nanocapsules were formulated from arginine-tethered reduction-responsive copolymers, P(ArgMA-co-DMA)-b-PPOPMA, microwave-absorbing AB and chemotherapeutic DOX using a double-emulsion method. The nanocapsules were internalized by cancer cells rapidly via major energy-independent pathways. Upon pulsed microwave irradiation, AB absorbed energy to generate a giant thermoacoustic shockwave, simultaneously decomposing into carbon dioxide and ammonia which enforced the cavitation damage effect. The thermoacoustic shockwave and gas burst also mechanically disrupted the intracellular organelles resulting in high-ratio cell necrosis and promoted the cytosolic release of DOX into the nucleus to initiate cell death. Importantly, in vivo results demonstrated significantly suppressed tumor growth by the pulsed microwave-triggered thermocavitation and drug release, and minimal systemic toxicity from the microwave treatment. Therefore, our study provides a new strategy for effectively engineering pulsed microwave-responsive nanomaterials for smart cancer therapy.