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Health

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Lasers help speed blood diagnoses

Combining lasers with a principle discovered by Alexander Graham Bell more than 100 years ago, researchers have developed a new way to collect high-resolution information about the shape of red blood cells.

Because diseases such as malaria can alter the shape of the body’s cells, the device may provide a way to accurately diagnose various blood disorders.

The study relies on a physical principle, known as “the photoacoustic effect,” originally discovered by Bell in 1880. The famed inventor observed that when a material absorbs light from a pulsing light source, it produces sound waves.

Since then, scientists have learned that the effect occurs because the object heats up as it absorbs light; the heat causes the object to expand, and this physical change leads to the emission of sound waves.

Today, researchers can induce the photoacoustic effect by using lasers. The most advanced lasers can pulse in the nanosecond range (once every 100 of nanoseconds), generating sound waves from cells and tissues that are at very high frequencies. The higher the frequency, the more information scientists are able to glean about the shape of the object.

Michael Kolios, a photoacoustics scientist at Ryerson University in Toronto, wondered whether he could use the photoacoustic effect to determine the shape of red blood cells.

His team developed a laser that pulses every 760 nanoseconds to induce red blood cells to emit sound waves with frequencies of more than 100 megahertz, one of the highest frequencies ever achieved.

Testing the laser on blood samples collected from a group of human volunteers, Kolios and colleagues showed that the high-frequency sound waves emitted by red blood cells in the blood samples revealed the tiniest details about the cells’ shapes.

The approach could accurately distinguish samples from a person with malaria, which is characterized by the swelling of red blood cells, from samples from a person with sickle cell anemia, in which the red blood cells distort into a serrated crescent shape, the team reported recently in the Biophysical Journal.

The method requires as few as 21 red blood cells. Standard blood tests, in contrast, need more than one drop of blood, and red blood cells need to be analyzed manually by pathologists with a microscope, a task that is slow and prone to human error.

The faster diagnosis with Kolios’ technology allows doctors to determine quickly whether the donor’s blood is disease-free immediately before a blood transfusion.

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