Quantitative detection of C-deuterated drugs by CARS microscopy and Raman microspectroscopy

The introduction of carbon-deuterium (C–D) bonds into drug compounds by organic synthesis is a non-invasive labelling approach, which does not alter the chemical and physiological properties of the drug itself. C-deuterated drugs exhibit characteristic vibrational signatures in the C–D stretching region around 2100–2300 cm−1, which avoids spectral interference with contributions from a complex biological environment. In this paper, the quantitative detection of C-deuterated drugs by Raman microspectroscopy and single-band CARS microscopy is examined. Concentration-dependent studies on drugs with aliphatic and aromatic C–D moieties were performed in a two-channel microfluidic chip, using the corresponding non-deuterated (C–H) isotopologues as an internal reference.