Raman spectroscopy - its utility for investigating ME/CFS

[Hutan]

A couple of labs at least (Mortem and Moreau) have done some work with Raman spectroscopy, trying to find differences between ME/CFS cells and cells from healthy controls.

As I understand it, it reports molecular signatures resulting from subjecting a sample to light, with the output being a series of peaks and troughs at different wavelengths. Molecules hit with the light produce particular wavelengths, and so the output can tell you about the molecules in the sample. Samples can be single cells.

It's a technology that seems to have a lot of promise, for cell sorting, for the identification of pathogens, including intracellular pathogens, and for making comparisons between healthy and dysfunctional cells.

This mini-review describes the technology and some of the things that can be done with it (it also has a nice overview of other cell-analysis techniques and their advantages and drawbacks).
Raman Spectroscopy—A Novel Method for Identification and Characterization of Microbes on a Single-Cell Level in Clinical Settings, 2022

I've tagged threads on studies using the technology with 'Raman'.

I thought it would be useful to have a place to note information that can help us analyse studies using this technique, and to gather ideas for future studies.

 

[Hutan]

I'm interested in the potential for this technology to identify pathogens cheaply and easily.
For toxins and extracellular pathogens in low concentrations (like Lyme?), there is this technique:

Kusić et al. successfully used magnetic beads coated with Legionella spp. specific polyclonal immunoglobulins for isolating single Legionella sp. cells from biofilm and subsequently identifying them with Raman spectroscopy (Kusić et al., 2014). Kearns et al. developed a bionanosensor based on magnetic separation and SERS, which can be used to identify microbes in concentrations as low as 101 CFU/mL in less than one hour (Kearns et al., 2017).

Issues with the technique include:
* currently, a lack of "fingerprints" - standard spectral signatures for comparisons
* difficulty comparing results from different instruments (which makes reliable controls run on the same machine under the same conditions very important)
* confounding produced by the culture media, culturing conditions, sample preparation method (and probably sample storage method too e.g. freezing)

The cost is currently high, but will probably not remain so.