By Monika L. Ignacak
The fact that lasers do not occur in nature sent Massachusetts General Hospital’s Dr. Malte Gather wondering if there is any fundamental reason why biological substances do not play a major role in lasing.
A ‘laser’ by definition is a device that emits light of high degree of spatial and temporal coherence resulting in a beam of very high degree of focus and precisely defined parameters. An optical gain medium of the laser is a material where the photon emission and amplification take place. The first functioning device emitting a laser was operated in 1960 by Nobel Prize winner Theodore H. Maiman. Since then only artificial or engineered materials have been used as the optical gain medium.
In June 2011, Dr. Gather and his colleague Dr. Seok Hyun Yun from Harvard Medical School reported in Nature Photonics the first biological laser i.e. a laser utilizing biological/natural material as an optical gain medium. Investigators used green fluorescent protein (GFP) in human cells as viable optical gain medium. Upon being charged up with light of higher energy GFP emits green light. In their experiment, Gather and Yun placed the individual human cell expressing GFP in a high-Q microcavity and exposed it to nanojoule/nanosecond pulses of blue light. The emitted narrow laser beam was bright, directional and had characteristic longitudinal and transverse modes. Additionally, the spherical shape of the cell acted as a lens refocusing light.
The authors suggested that in future the biological cell laser might be applied in bringing optical communications and computing into the realm of biotechnology, especially in projects where electronic devices interface with live cells. The cell laser could also be implemented in advanced cytometry or a photodynamic therapy which is an emerging early- and end-stage cancer treatment. The specific wavelength light generated by biological laser would be used to activate photosensitizer, a photo sensitive drug, which causes excited singlet oxygen formation. The oxygen aggressively reacts with biomolecules around and destroys cancer cells.
Malte C. Gather, Seok Hyun Yun. Single-cell biological lasers. Nature Photonics, 2011; DOI: 10.1038/nphoton.2011.99
Monika L. Ignacak has Ph.D. in Molecular Biology and experience in molecular neuroscience and molecular biology of steroid hormones from the Poznan University of Medical Sciences and the University of Cincinnati. Currently she works at the RIC Center, where she is involved in developing effective data organizing system.