More medical applications using optics

It's hard to keep up with the ever-increasing number of ways in which light can be used to push on the frontiers of medical science. Here are just a few that have been reported on in recent days.

Raman tweezers were first demonstrated more than six years ago¹ and now researchers from the University of Naples, Italy have been putting them to good use in the study of blood disorders². They used a laser to trap individual blood cells and then, with the same laser, they were able to characterise the cell using Raman spectroscopy. They were also able to examine the mechanical properties of the cells by using two optical traps to deform them.

In another application, Raman spectroscopy was teamed up with Optical Coherence Tomography (OCT) in a system that may one day be used for the diagnosis of skin cancers³. The researchers in the US and the Netherlands were able to combine the two techniques in a single instrument, exploiting the high speed and spatial sensitivity of OCT, and the biochemical specificity of Raman spectroscopy.

Cancer was also the focus of a new technique reported by researchers at the University of Texas⁴. They used antibodies to seek out cancerous cells, which is a technique commonly used to deliver agents that destroy the cancer cells, either by chemical or radioactive means. These antibodies, however, were coated with carbon nanotubes, which then became attached to the cancerous cells. By exposing them to near infra-red light, the cells were heated and thereby destroyed. This method is capable of safely penetrating normal tissue and killing only the cancerous cells, and may possibly lead to new cancer therapies in the future.

1) C. Xie, M. A. Dinno, and Y. -q. Li, "Near-infrared Raman spectroscopy of single optically trapped biological cells," Opt. Lett. 27, 249-251 (2002)| doi:10.1364/OL.27.000249

2) Raman tweezers probe red blood cells - Researchers move closer to understanding devastating haemoglobin-related blood disorders thanks to a combination of optical tweezers and Raman spectroscopy. [Optics.org - research]

3) Combined Raman-OCT targets skin cancer - The first system to combine Raman spectroscopy and optical coherence tomography could improve the diagnosis of skin cancers. [Optics.org - research]

4) Nanotechnology, biomolecules and light unite to "cook" cancer cells - Researchers are testing a new way to kill cancer cells selectively by attaching cancer-seeking antibodies to tiny carbon tubes that heat up when exposed to near-infrared light. [UTsouthwestern.edu]