Stanford scientists fit light-emitting bioprobe in a single cell

If engineers at Stanford have their way, biological research may soon be transformed by a new class of light-emitting probes small enough to be injected into individual cells without harm to the host.

Welcome to biophotonics, a discipline at the confluence of engineering, biology and medicine in which light-based devices – lasers and light-emitting diodes (LEDs) – are opening up new avenues in the study and influence of living cells.

The team described its probe in a paper published in Nano Letters. It is the first study to demonstrate that tiny, sophisticated devices known as light resonators can be inserted inside cells without damaging the cell. Even with a resonator embedded inside, a cell is able to function, migrate and reproduce as normal.

Applications and implications
The researchers call their device a "nanobeam," because it resembles a steel I-beam with a series of round holes etched through the centre. This beam, however, is not massive, but measure only a few microns in length and just a few hundred nanometers in width and thickness. It looks a bit like a piece from an erector set of old. The holes through the beam act like a nanoscale hall of mirrors, focusing and amplifying light at the center of the beam in what are known as photonic cavities.

These are the building blocks for nanoscale lasers and LEDs.

"Devices like the photonic cavities we have built are quite possibly the most diverse and customisable ingredients in photonics," says the paper's senior author, Jelena Vuckovic, a professor of electrical engineering. "Applications span from fundamental physics to nano-lasers and bio-sensors that could have profound impact on biological research."