Scientists create breakthrough virus-sized bubbles for medical imaging

The invention of the tiniest free-floating bubbles is expected to significantly improve medical imaging in the coming years.

Bio-engineers at Rice University have developed these gas-filled protein bubbles that are small enough to travel throughout the body, reaching areas previously inaccessible.

This medical tool holds the potential to advance ultrasound imaging and drug delivery to treat various complications.

“This breakthrough opens new avenues for ultrasound-mediated disease treatment, impacting future medical practices and patient outcomes. The research has notable implications for treating cancers and infectious diseases, as lymph-node-resident cells are critical targets for immunotherapies,” said George Lu, assistant professor of bioengineering, and study author.

50-nanometer bubbles

The new microbubble is a type of gas vesicle (GV), which is almost the size of a virus (50-nanometer). Interestingly, the newly developed free-floating structures are diamond-shaped and not round as one may expect.

Because of their small size, they can easily navigate through the body, reaching lymph nodes and other remote areas.

The researchers used a combination of cutting-edge techniques to create the structures as well as to unravel how these bubbles worked within the body.

As per the press release, genetic engineering brought them to life, nanoparticle characterization methods offered a detailed picture of their properties, electron microscopy revealed their distribution within the body at a microscopic level, and ultrasound imaging helped assess their interaction with sound waves.

“More broadly, this represents a significant advancement in material design, potentially leading to innovative applications across various scientific fields,” Lu said. “Because these nanostructures are composed entirely of proteins and are produced within living bacteria, they exemplify how biogenic materials can surpass the performance of synthetic materials.”

Nanobubbles testing

Microbubbles or nanobubbles have already been used for ultrasound imaging as well as gene and medication delivery via ultrasound.

These bubbles offer valuable insights into specific cells and molecules.

However, their large size (1-10 micrometers) hinders their ability to pass throughout the body, as they get stuck in the bloodstream and other biological barriers. This limitation has driven the development of smaller alternatives for broader applications.

In lab-based experiments, the team demonstrated that these new nanobubbles were able to pass through tissue barriers, and reached immune cell communities residing in lymph nodes.

The researchers highlight that electron microscopy provided a unique look into the lymphatic system. Images revealed the nanostructures accumulating in large numbers within immune cells crucial for triggering the body’s natural defenses.

This discovery opens doors for exploring the use of these nanostructures in developing new immunotherapies, cancer prevention methods, tools for earlier disease detection, and even treatments for infectious diseases.

“The rationale was to harness their small size and acoustic properties for biomedical applications. This work represents a pioneering design of functional gas-filled protein nanostructures small enough to cross into the lymphatic system,” Lu said in the press release .

There’s still more work to be done. Researchers will be looking at the long-term safety of these bubbles for use in living organisms and check unwanted immune responses triggered by them.

The development has been detailed in the journal Advanced Materials.