In an exciting first for both Bioengineering and Biomedicine, researchers Malte C. Gather & Seok Hyun Yun at the Wellman Center for Photomedicine* have successfully induced living cells to generate nano-second laser pulses in a specially designed micro-cavity.
While nano-scale (that’s billionths of a meter) lasers have been previously developed and demonstrated, these earlier lasers relied on some external source as a gain medium. This new ‘living laser’ exploits a now quite common biological mechanism: Green Fluorescent Protein (GFP). They are the first, self-contained “biological systems” to be used to generate laser light.
According to the on-line abstract, the researchers wanted to “show that fluorescent proteins in cells are a viable gain medium for optical amplification…[and]…demonstrate in vitro protein lasers using recombinant GFP solutions and introduce a laser based on single live cells expressing GFP.”
The actual laser is a two-component system: the first component is a solution of active GFP-producing cells, and the second part consists of a tiny, inch-long tube with tiny mirrors at each end (separated by just 20 micrometers), forming a micro-optical resonator as the cells are pumped into the tube (see schematic, click to enlarge).
“On optical pumping with nanojoule/nanosecond pulses, individual cells in a high-Q microcavity produce bright, directional and narrowband laser emission…” Emissions that were easily detected.
What’s more, the GFP-generating cell’s remained alive and continued to emit photons — the quantum light particles that are the basis of any laser — “even after prolonged lasing action.”
GFP was originally isolated from jellyfish and its genetic secrets have been decoded and bio-engineered into other organisms and animals for many years now (including dogs, frogs, rabbits and monkeys). The fluorescing protein gene is typically inserted into a cell’s genome, causing the cell to fluoresce when certain genes are expressed, or certain cell processes become active.
The development is expected to help advance new forms of intracellular sensing, cytometry (measuring chemical activity within a cell) and imaging…and may even, one day be used to detect and destroy cancer cell.(Author’s note: what’s a laser for if ya can’t zap bad stuff with it?).
* The Wellman Center for Photomedicine is part of Massachusetts General Hospital (the oldest and largest teaching hospital of Harvard Medical School).
Top image: Cellular laser modes: measured (left) and calculated Ince–Gaussian (right) transverse mode pattern of the single-cell laser. From the paper Single-cell biological lasers (by Malte C. Gather & Seok Hyun Yun) published on-line: June 12, 2011, in Nature Photonics.
Schematic: From the paper Single-cell biological lasers (by Malte C. Gather & Seok Hyun Yun) published on-line: June 12, 2011, in Nature Photonics.