Using Sound Waves to Sort Blood-Based Nanoparticles

Engineers at Duke University developed a gadget that uses sound waves to separate and sort the tiniest particles found in blood within a couple of minutes. The technology is established on a concept referred to as “virtual pillars” and has potential in both scientific research and medical applications.

The novel technology, dubbed Acoustic Nanoscale Separation via Wave-pillar Excitation Resonance, or ANSWER for short, not only pulls these nanoparticles from biofluids quickly but also sorts them into size categories believed to have distinct biological roles. The findings were published online in the journal Science Advances.  

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Sorting Hard-to-Obtain Nanoparticles with High Potential

All cells in the body release tiny biological nanoparticles named “small extracellular vesicles” (sEVs), which may play a vital role in cell-to-cell communication and disease transmission. For instance, some recent discovery of sEV subpopulations has excited researchers because of their potential in non-invasive diagnostics, such as the early detection of cancer and Alzheimer’s disease. 

Despite its significant potential in medical diagnosis and treatment, the current technologies for separating and sorting them take several hours or days, in addition to its inconsistency in production rate. The main challenge of adapting nanoparticles in the biomedical field is to create a more time-efficient method while avoiding contamination.

In this study, scientists successfully made extracting and sorting high-quality sEVs as simple as pushing a button and getting the desired samples faster than expected, which overcame the main obstacles in this field.

How the Time-Saving Sorting Device Works

The new device uses a single pair of transducers to generate a standing sound wave that envelops a narrow, enclosed channel filled with fluid. This sound wave “leaks” into the liquid center through the channel walls and interacts with the original standing sound wave. This interaction creates a resonance that forms “virtual pillars” along the center of the channel by controlling the wall thickness, channel size, and sound frequency. As particles cross over the pillars, they get pushed toward the edges of the channel. And the bigger the particles, the bigger the push.

The ANSWER platform successfully sorts sEVs into three subgroups with 96% accuracy for nanoparticles on the larger end of the spectrum and 80% accuracy for the smallest. The flexible system can also adjust the number of groupings and ranges of sizes with simple updates to the sound wave parameters. Each experiment only took ten minutes to complete, whereas other methods, such as ultra-centrifugation, can take several hours or days.

In the future, the researchers hope to continue improving the ANSWER technology so that it can be efficient in purifying other biologically relevant nanoparticles such as viruses, antibodies, and proteins.

Author

Nai Ye Yeat