New Quantum Dots Hold Potential for Biological Imaging

Most biological tissues are almost as transparent as glass for particular frequencies of short-wavelength infrared light according to MIT researchers.  This research team fabricated tiny particles that are injectable at least into animals. From within the body, these particles emit the penetrating frequencies of short-wavelength infrared. The method may offer a new way of producing detailed images of internal body structures.

The new findings, based on the use of quantum dots, is detailed in a paper in the journal Nature Biomedical Engineering, by MIT research scientist Oliver Bruns and 23 others.

While wavelengths of about 1,000 to 2,000 nanometers are were known to potentially provide better biological tissue imaging, scientists didn’t have high-quality emitters, according to article author Oliver Bruns. The lighting emitting particles (quantum dots) are nanocrystals of semiconductor materials that emit light at a frequency that can be precisely tuned. This frequency tuning requires control over the exact size and composition of the particles.

Quantum Dots with Short-Wavelength Emission

The solution was developing quantum dots whose emissions matched the desired short-wavelength infrared frequencies. A paper by graduate student Daniel Franke and others from the Bawendi group initially described the synthesis of these new particles in Nature Communications last year.

Bruns said that the quantum dots are so bright that their emissions can be captured with very short exposure times. This allows both single images and even video that captures details of motion, such as the flow of blood. The new light-emitting particles are also the first that are bright enough to allow internal organ imaging of mice while they are awake and moving.

The scientists plan to conduct preclinical research in animals, as the compounds contain some materials that are unlikely to be approved for use in humans. They are also working on developing versions that would be safer for humans.

Bruns said the imaging method relies on a newly developed specialized detector of a commercially produced camera made of indium gallium arsenide.