Researchers in bioengineering have created extremely small and stable gas-filled protein nanostructures that could transform the fields of ultrasound imaging and drug delivery for the treatment of cancers and infectious diseases. These novel diamond-shaped 50-nanometer gas vesicles (50-NM GVs) are the smallest stable, freely floating structures ever produced for medical imaging, roughly equivalent in size to viruses.
Traditional microbubbles have played a crucial role in recent advancements in ultrasound imaging as well as in delivering genes and drugs using ultrasound. Serving as contrast agents, they offer detailed insights into targeted biomarkers or cell types. However, their large size (ranging from 1-10 micrometers in diameter) limits their ability to cross biological barriers effectively, confining their effectiveness to well-vascularized tissues.
In contrast, the new 50-NM GVs have shown the ability to penetrate tissues, with research indicating their successful reach of essential immune cell populations in lymph nodes. This breakthrough opens up new opportunities for imaging and administering treatments to previously unreachable cells.
Observations from electron microscopy images of lymphatic tissue demonstrate significant numbers of these nanostructures gathering within cells that play a crucial role in initiating the innate immune response. This suggests their potential utility in immunotherapies, cancer prevention, early diagnosis, and the treatment of infectious diseases. The findings have been published in the journal Advanced Materials.
“This development paves the way for ultrasound-based disease therapies, influencing the future of medical practices and patient outcomes. The implications are particularly noteworthy in the realms of cancer and infectious disease treatment, as immune cells residing in lymph nodes are key targets for immunotherapies,” explained George Lu, the lead author of the study and an assistant professor of bioengineering as well as a scholar at the Cancer Prevention and Research Institute of Texas.
The research methodology involved genetic engineering, nanoparticle characterization techniques, electron microscopy, and ultrasound imaging to study the distribution and acoustic response of these nanostructures.
“The goal was to utilize their small size and acoustic properties for medical purposes,” Lu elaborated. “This study represents an innovative design of functional gas-filled protein nanostructures that are small enough to enter the lymphatic system.”
The study also suggests future research directions, such as evaluating the nanobubbles’ biosafety and immunogenicity, determining the ideal ultrasound parameters for in vivo applications, and more.
“On a broader scale, this marks a considerable advancement in material design, potentially leading to inventive applications across various scientific fields,” highlighted Lu. “As these nanostructures are entirely composed of proteins and are created within living bacteria, they exemplify how biogenic materials can outperform synthetic materials.”
