The core insight of the review is that focused ultrasound, or FUS, does far more than heat tissue. When an acoustic beam is focused to a small target volume, it deposits energy through three broadly distinct mechanisms: mechanical effects driven by acoustic radiation forces, cavitation-driven effects arising from the dynamics of microscopic gas bubbles, and thermal effects from the absorption of ultrasound energy. Cavitation is particularly dramatic. When pre-existing or newly formed microbubbles oscillate and then implode under acoustic pressure, they generate localized regions of extreme pressure and temperature, producing shockwaves and microjets that can stretch the cell membrane into transient, tiny pores—a phenomenon called sonoporation that allows molecules and ions to pass through without permanently damaging the cell. In parallel, acoustic radiation forces transfer momentum to tissue during sound propagation, displacing and deforming cell membranes at the focal point, while acoustic streaming induces steady shear stresses that further perturb cellular and subcellular structures.

These physical perturbations are not simply destructive; they are informative. The Rice team emphasizes that cells interpret FUS-induced mechanical forces through mechanotransduction—the conversion of mechanical stimuli into biochemical signals. Matrix-anchored cells detect these disturbances through the integrin-adhesion plaque complex, transmitting them along actin stress fibers, while suspended cells experience shear force directly at the plasma membrane. Forces propagating through the cytoskeleton can even reach the nucleus via the linker of nucleoskeleton and cytoskeleton complex, influencing chromatin organization and gene expression. But the most striking mechanistic story involves mechanosensitive ion channels. PIEZO1 has been repeatedly identified as a primary mechano-gated channel responsive to acoustic radiation force-driven membrane tension: low-intensity FUS rapidly activates PIEZO1-dependent calcium influx in osteoblastic precursor cells, promoting ERK signaling and cytoskeletal remodeling, while in prostate cancer models nonthermal ultrasound pulses induce PIEZO1-mediated calcium entry that causes mitochondrial depolarization and caspase-3 activation, sensitizing tumors to TRAIL-mediated apoptosis. The TRPV4 channel, meanwhile, has emerged as a key sonosensor at the blood-brain barrier, where cavitation and radiation force-induced membrane strain gates TRPV4-dependent calcium influx, engaging a Ca²⁺/PKC-δ cascade that drives reversible tight-junction opening. Two-pore domain potassium channels such as TREK-1 and TRAAK add another dimension, converting FUS-induced membrane tension into hyperpolarizing leak currents that dampen neuronal excitability—in one remarkable study, transcranial low-intensity FUS targeting TRAAK-overexpressing brain neurons suppressed sympathetic drive and prevented malignant arrhythmias after myocardial infarction.

The therapeutic implications of this channel-level control are profound. Calcium signaling is a master regulator of cell fate, and FUS can push it in either direction depending on acoustic parameters. Low-intensity pulsed ultrasound enhances tissue regeneration and migration, whereas elevated mechanical forces trigger apoptosis through extensive DNA damage or altered mitochondrial permeability. In hepatocellular carcinoma models, FUS stimulation suppressed tumor proliferation by more than 70 percent in H22-HCC cells and more than 83 percent in Hepa1-6-HCC cells, along with significantly prolonged survival. In immunotherapy contexts, high-intensity ultrasound triggered the calcium-dependent NFAT pathway in T cells, producing stronger immune responses and memory that effectively inhibited tumor recurrence and metastasis. The review also highlights FUS’s capacity to transiently and locally open the blood-brain barrier—a critical translational goal, since passive diffusion across the barrier typically favors only small lipophilic molecules under roughly 400 to 500 Daltons, yet nearly 98 percent of approved small-molecule drugs exceed this threshold. Preclinical and early clinical studies of FUS-mediated BBB opening demonstrate spatially defined, reversible increases in regional permeability that allow therapeutic agents and biologics to access previously restricted brain regions.

The second pillar of the framework concerns nanoparticles as active partners rather than passive cargo holders. Compared with microbubbles—which are 1 to 8 micrometers in diameter, confined largely to vascular compartments, limited in drug-loading capacity, and short-lived in circulation—nanoparticles in the 20 to 200 nanometer range offer tunable size, broad surface functionalization, prolonged systemic circulation, and the ability to access extravascular and interstitial spaces. Crucially, nanoparticles can be engineered as transducers that convert acoustic cues into on-demand structural reconfiguration or bond cleavage. The review catalogs three classes of FUS-triggered chemical bond scission. Surface-anchoring bonds can be severed to shed protective shells: silica core-shell nanoparticles bearing a PEG brush attached via force-labile azo bonds remain stable during circulation until FUS-induced mechanical perturbation triggers PEG detachment, activating free radical generation and cytotoxicity. Prodrug-linker bonds embed sono-labile chemistry at the drug-carrier junction: singlet oxygen generated by therapeutic ultrasound can cleave a urea linkage between carboxyferrocene and methylene blue, switching an inert nanodrug into a Fenton-active ferroptosis inducer at the tumor site. Backbone and crosslink bonds determine whether ultrasound destabilizes the entire carrier framework, as in diselenide-crosslinked microgels that degrade into water-soluble chains under low-frequency ultrasound, or thermosensitive hydrogels that disintegrate under mild FUS hyperthermia to release ultrasmall 1-to-5-nanometer doxorubicin-loaded secondary nanoparticles deep into tumor microvasculature.

Not all FUS-nanoparticle interactions require covalent bond rupture, however. The review details reversible physical mechanisms in which ultrasound controls membrane properties, aggregation states, or spatial distribution without permanent chemical modification. Thermosensitive liposomal bilayers tuned with DPPC/DSPC/MSPC compositions remain stable at 37 degrees Celsius but generate transient membrane defects under mild FUS hyperthermia, accelerating release of encapsulated carboplatin and membrane-associated SN-38. In a triple-negative breast cancer model, FUS-triggered doxorubicin liposomes increased vascular permeability, promoted immunogenic cell death, and reprogrammed a suppressive tumor microenvironment into an immune-responsive one that enhanced checkpoint blockade efficacy. Piezoelectric barium titanate nanoparticles activated by FUS generate reactive oxygen species or trigger nitric oxide release, altering stromal components such as collagen and fibronectin—demonstrating that nanoparticles can actively reshape the tumor microenvironment in concert with acoustic stimulation.

The third and perhaps most forward-looking pillar of the review is its argument for advanced in vitro testing platforms. The authors note that the National Institutes of Health has recently shifted research priorities toward human-based technologies, establishing the Office of Research Innovation, Validation, and Application to reduce reliance on animal models, which frequently fail to translate—many candidate therapies fail in phase I and II clinical trials despite promising rodent results, owing to fundamental interspecies differences in metabolism, molecular interactions, and disease progression. Conventional two-dimensional cell culture fares no better: flat, rigid substrates cannot capture the three-dimensional multicellular architecture of tumors, the mechanical cues of extracellular matrix stiffness, or the cell-cell interactions—including bidirectional mitochondrial transfer between cancer and immune cells—that regulate therapeutic response. Intermediate systems such as Transwell chambers, 3D hydrogel cultures, and tumor organoids each address parts of this gap, but they remain limited in their ability to support controlled perfusion and spatiotemporal regulation.

Cancer-on-a-chip platforms close this remaining gap. These microfluidic systems integrate self-assembled vascular networks, defined extracellular matrix structures, and regulated flow within optically accessible formats, enabling real-time, quantitative analysis of nanoparticle penetration, distribution, and release under physiologically controlled conditions. The review describes how vascularized chip models—including glioblastoma-on-a-chip systems—allow assessment of nanodrug formulations designed to preserve vascular integrity during FUS exposure, while stiffness-tunable hydrogel microfluidic systems reveal how matrix mechanics regulate cancer cell migration and invasion. When FUS is incorporated directly into these chips, researchers can resolve in real time how acoustic stimulation, nanoparticle activation, and tumor-vascular-immune interactions couple together—effects that static culture systems average away and that xenograft models obscure. One cited study integrated FUS with microbubble oscillation in an organ-on-chip model to disrupt the extracellular matrix and enhance interstitial drug transport, while other work showed FUS activating microglia, hinting at immune modulation possibilities in brain tumors.

The authors are candid about the challenges that remain. The effective and safe ultrasound dose range for combined FUS-nanoparticle therapy, as well as repeated dosing strategies, is still unclear, and complex multicomponent formulations need standardization for large-scale production, quality control, and regulatory approval. Yet the trajectory is clear: next-generation cancer-on-a-chip platforms that reconstruct vascular perfusion, matrix mechanics, immune infiltration, and a tunable field for FUS stimulation—ideally built from heterogeneous patient samples—could serve as a translational bridge from nanomedicine design to clinical implementation, ultimately enabling personalized assessment of FUS-responsive therapies. If that bridge is crossed, the humble sound wave, working in concert with engineered nanoparticles, could become one of the most versatile tools in oncology: a knife-less surgeon, a courier for drugs, and a reprogrammer of the tumor microenvironment, all in one focused beam.