Identifying cells from their biophotonic profile
Raman spectroscopy is based on the Raman effect: when a molecule is exposed to laser light, a small fraction is scattered with a shift in frequency compared to the incident light. This shift is highly specific for each molecule – as unique as a fingerprint.
Raman spectra from airborne microorganism. Colonies were scraped off the Agar plate and resolved in buffer. Raman spectra were taken from individual living bacteria and fungi utilizing the simultaneous trapping effect of the Raman Laser configuration. Raman spectra of colored colonies differ at wavenumbers corresponding to carotenoids.
Raman spectroscopy allows to identify and analyze cells with a high degree of precision and specificity without the need of biochemical markers, fluorescent labels, antibodies or beads. It works within liquids under culture conditions and enables investigation of cellular components unaffected and preserved for further use.
Raman spectroscopy has long been used successfully as a contact-free technique for material characterization. More recently, scientists have demonstrated its applicability to the field of biology and medicine: several research teams have independently shown that the combined Raman spectra of all biopolymers within a cell form distinct clusters according to cell type and state of differentiation and activity.