Abstract

Reza Mokhtar*, Mohsen Paknejad, Dr. Mohsen Mohammadpour, Samaneh Bandehali, Mohammad Reza Parsa*, Mostafa Asadollahi*

ABSTRACT

Glioblastoma multiforme (GBM) stands as one of the most treatment-resistant brain tumors, largely due to its invasive nature and the restrictive characteristics of the blood–brain barrier (BBB). This study presents a novel nanotechnology-based strategy designed to locally generate protons within tumor microenvironments using core–shell nanoparticles that respond to ultrasound. These particles, optimized for blood–brain barrier permeability and clinical safety, enable finely controlled, site-specific release of cytotoxic protons, resulting in >70% tumor volume regression and >18-month median survival in a Phase I/IIa clinical study. Advanced spectroscopic, imaging, and computational validation confirm robust proton emission and selective targeting, making this the most compelling alternative to costly proton beam therapy to date. These nanoparticles are engineered with a polyvinyl alcohol (PVA) and graphene oxide (GO) hybrid core, enveloped by a piezoelectric zinc oxide (ZnO) shell, and coated with palladium nanoparticles to facilitate catalytic ionization. When activated by focused ultrasound (1.5 MHz, 3 W/cm²), the system achieved a measurable in vitro proton release (average 0.29 ± 0.04%), as confirmed by LC-MS analysis and γ-H2AX assays. Simulations conducted with COMSOL and verified through experimentation revealed that the energy spectrum of the emitted protons—ranging from 4 to 10 keV—falls within the effective range for inducing DNA double-strand breaks. Cytotoxicity assays using U87 glioblastoma cells showed a 68.7% apoptosis rate, while primary cortical neurons from mice displayed high viability (>94%), indicating excellent tumor selectivity. A preliminary Phase I clinical trial involving 18 patients with recurrent GBM found the treatment to be safe, with no serious toxicities, and showed a favorable tumor response in 44% of cases. These results highlight the potential of ultrasound-activated, in situ proton generation as a low-cost, minimally invasive alternative or complement to conventional glioma therapies.