Light-Emitting Bioprobe Fits 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.

It is the first study to demonstrate that sophisticated engineered 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.

The researchers call their device a "nanobeam," because it resembles a steel I-beam with a series of round holes etched through the center. These beams, however, are 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 beams 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.

At the cellular level, a nanobeam acts like a needle able to penetrate cell walls without injury. Once inserted, the beam emits light, yielding a remarkable array of research applications and implications. While other groups have shown that it is possible to insert simple nanotubes and electrical nanowires into cells, nobody had yet realized such complicated optical components inside biological cells.