This compact system allows scientists to see biological molecules in a totally new way

The researchers combined laser techniques and an ingenious detection scheme to create a powerful new molecular imaging system, a faster and easier way to determine the identity of microscopic molecules. Basically, it's an advanced but surprisingly simple microscope.

Radiation of the average infrared light on complex molecules such as proteins and observing how they react can provide detailed information about their structure and the function they perform. But today, infrared sources such as lasers, heaters and particle accelerators may lack the necessary brightness, wavelengths or resolution, or be too expensive for these purposes . There are also few effective detectors for these average infrared wavelengths. The group of scientists behind the project hopes to overcome these limitations with its new system.

"Developing these tools is exciting to see how it can go in different directions and open up new opportunities," study author Scott Diddams, assistant professor and NIST scholar at the University of Colorado, Boulder, told Gizmodo. "There is something exciting about a physicist working with biologists using microscopy for medical tests."

You may remember from high school chemistry that elements absorb certain wavelengths of light. Illuminating light with different wavelengths and seeing what has been absorbed is a way of creating "fingerprints" that identify molecules. Biological molecules absorb a lot (or react by other means) when they are hit by light in the middle infrared, beyond what our eyes can see. But the range of the average infrared is a range of wavelengths particularly difficult to produce during experiments and to detect in detectors. This can complicate the fingerprinting of many biological molecules.

The researchers transmit near infrared laser pulses through a series of optics, including special fibers, crystals and arrays. This generates a broad spectrum of medium infrared light with regularly spaced wavelengths, such as the teeth of a comb. In fact, these tools are called optical frequency combs. This light hits a test sample, which absorbs some of the wavelengths while allowing the remainder to pass through, giving a distinct signature or fingerprint. Then they combine this laser with another near-infrared laser and send the attached beam into a crystal. The electric field in the middle infrared alters the polarization or orientation of the laser in the infrared in a direct and predictable way, easily measurable by inexpensive detectors.

All this is inscribed in a laboratory system the size of a table, according to the document published in Science Advances.

Mengjie Yu, a postdoctoral fellow in Applied Physics at Harvard and uninvolved in research, told Gizmodo that this method could be "revolutionary beyond laboratory use" to identify "lipids, proteins, biological markers for breath analysis or for medical purposes, and gas detection for the monitoring of the industrial control environment. " She was excited about how she solved two problems: first, she is expanding the range of optical combs in the mid-infrared, and second, she is able to detect results that are normally difficult to detect.

The search may seem esoteric, but it is a big problem when it comes to making this type of measure accessible. "If you wanted comparable light sources, you had to go to a large user center, put yourself in a queue and wait for the use of the light source," Diddams told Gizmodo. "We have demonstrated that you can do this in a compact lab that is relatively easy to build on a few square feet."