Scientists have "armed" living cells with tiny lasers

DailyTechInfo based on AAAS News: Scientists arm cells with tiny lasers 

A group of physicists and biologists from the University of St. Andrews, St. Andrews, Scotland, successfully implanted tiny lasers inside living cells of artificially grown tissue. These tiny coherent light sources make it possible to monitor for many days and weeks the processes of movement and functioning of individual cells, which is required in some cases to diagnose and determine treatment methods for various diseases, in particular, oncological.

To create a laser of any scale, two things are required – the working body of the laser, a material that can emit light, passing into an excited state due to energy from an external source. The second part of the laser is a resonant cavity, which amplifies the light of a strictly defined wavelength and makes it coherent.

Previously, scientists have already tried to create laser light sources inside living cells by launching special fluorescent proteins inside these cells and placing them in a certain volume that acts as an optical resonator. However, Scottish scientists took a step further, they were able to "persuade" a living cell so that it absorbed a tiny sphere made of plastic, which acts simultaneously as both a working body and a resonant cavity. In the image below, this sphere is shown in green.

Figure from an article in Nano Letters (Schubert et al., Lasing within Live Cells Containing Intracellular
Optical Microresonators for Barcode-Type Cell Tagging and Tracking) – VM.

A fluorescent dye has been introduced into the material of the sphere, which emits light with a certain wavelength, absorbing photons of light with arbitrary wavelengths. The emitted light resonates inside the sphere, amplifying and acquiring coherence. Naturally, when manufacturing spheres of such small sizes, it is impossible to accurately observe their identical dimensions. Therefore, all microlasers made in this way study light whose wavelengths differ by a small amount. However, this difference can be detected by highly sensitive sensors and distinguish one instance of the cell from another.

Currently, scientists have managed to introduce lasers only into artificially grown cells. However, they have already started working towards the development of implantation technology that will allow the introduction of such spherical lasers into living cells of body tissues, which can be used to track the movement of cells of various types, for example, blood cells or malignant tumor cells, right inside the human body.

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24.07.2015