Futuristic laser therapy is currently being investigated for numerous medical applications. Potential applications include the destruction of cancer cells, removing diseased tissue from delicate areas, blasting away toxic brain proteins, as well as acting as a biosensor to detect and monitor disease. However, miniaturizing and placing these devices inside the body at the site of disease greatly expands sensitivity and accuracy.
Nanolaser doesn’t damage tissues
Now, a study led by researchers at Northwestern University develops a tiny bio-compatible nanolaser which could, theoretically, be implanted inside living tissues without causing them damage. The team states the nanolaser measures less than 150 nanometers in thickness and requires a minimal amount of power. Furthermore, the nanolaser can fit and function inside living tissues, with the potential to sense disease or treat deep-brain neurological disorders, such as epilepsy. The study is published in the journal Nature Materials.
Previous studies show the design of nanolasers are similar to conventional semiconductor lasers in common use for several decades. The difference is the cavities of nanolasers are exceedingly small, on the order of the wavelength of the light they emit. Since they mostly generate visible and infrared light, the size is on the order of one-millionth of a meter.
This means nanolasers tend to be less efficient than their larger counterparts, requiring shorter wavelengths like Ultraviolet light to be powered, which can also damage surfaces or tissues being worked on. The current study develops a biocompatible nanolaser powered with longer wavelengths of light to emit at shorter wavelengths, allowing higher accuracy deeper within the body.
The current study develops a nanolaser platform using photon upconversion. In upconversion, low-energy photons are absorbed and converted into one photon with higher energy. Results show these low-energy, bio-friendly infrared photons upconvert to visible laser beams. Data findings show the laser beam can function under low powers and is vertically much smaller than the wavelength of light.
Results show the nanolaser is transparent and can generate visible photons when optically pumped with light invisible to the human eye. Data findings show the nanolasers operate at powers orders of magnitude smaller than those observed existing lasers.
An imaging system in vivo
The lab states their nanolaser shows specific promise for imaging in living tissues. They explain longer wavelengths of light are needed for bioimaging because they can penetrate farther into tissues than visible wavelength photons. Conversely, shorter wavelengths of light are often desirable in those same deep areas.
The team surmises they have designed an optically clean nanolaser system with the potential to be used inside the body. For the future, the researchers state the continuous wave, low-power characteristics of their biocompatible nanolaser will open numerous new applications, especially in biological imaging.
Source: Northwestern University
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