SonoPIN: Ultrasound‑Guided Microbubbles Deliver Large Cancer Drugs with Pinpoint Precision

Researchers at Duke University have developed a new ultrasound‑based method called SonoPIN (“Sonoporation‑assisted Precise Intracellular Nanodelivery”) that helps large anticancer molecules get inside tumor cells with high precision, while causing minimal damage to healthy tissue. In early lab experiments, the technique killed about half of the targeted cancer cells, while more than 99% of non‑targeted cells stayed alive, suggesting it could become a much more selective and less toxic kind of cancer therapy.

The work focuses on a class of drugs called PROTACs (Proteolysis‑Targeting Chimeras), which force cells to destroy specific proteins by tagging them for the cell’s own protein‑degradation machinery. Once these proteins are removed, cancer cells lose a key driver of survival and are pushed toward programmed cell death, or apoptosis. However, PROTACs are too large and complex to easily cross cell membranes, and systemic delivery can trigger unwanted side effects in normal tissues that also depend on those proteins, which has limited their clinical use so far.

SonoPIN gets around this by using microbubbles and focused ultrasound to physically open temporary pores in the cell membrane. Microbubbles, often used as contrast agents in diagnostic ultrasound, are coated with synthetic nucleic acid “homing” strands that bind preferentially to receptors on tumor‑cell surfaces, so they accumulate mainly on cancer cells. When focused ultrasound is applied to the tumor area, the microbubbles oscillate and collapse, producing tiny jets of fluid and local shock‑like forces that puncture the nearby cell membranes. Large molecules, such as PROTACs that are present in the surrounding fluid, can then flow directly through these pores into the targeted cells. The membrane quickly reseals within seconds to minutes, restoring the barrier and helping to protect healthy cells from unwanted drug entry.

In experiments, the team optimized the ultrasound settings and then attached fluorescent tags to the PROTACs so they could track how much drug actually entered the cells. After just one minute of ultrasound exposure, the fluorescence signal in SonoPIN‑treated cancer cells was about seven times higher than in cells treated with conventional delivery methods, indicating a dramatic increase in intracellular drug levels. This led to a roughly 70% reduction in target protein levels in the targeted cells, while the protein remained largely untouched in non‑cancerous cells. As a result, about half of the targeted cancer cells died through apoptosis, while non‑targeted cells maintained more than 99% viability, underscoring the selectivity of the approach.

Because SonoPIN works by mechanically forcing molecules through the membrane instead of relying on the cell’s normal biological uptake pathways, the same platform could, in principle, deliver other bulky payloads such as gene‑editing complexes or mRNA, opening the door to a broader range of next‑generation cancer therapies. Even though the technology is still at a very early stage, it has already been patented, and several Duke‑affiliated sources describe it as a potential foundation for a new generation of non‑invasive, spatially controlled cancer treatments.

Source.