An infrared sensor system for the analysis and differentiation of living mammalian cells using D₂O based microfluidics

In this study, we designed and realized a sensor platform using deuterium oxide (D₂O) based microfluidics to allow in vitro infrared (IR) analysis of living cells. Using D₂O instead of H₂O based medium successfully resolved the high IR absorption issue of H₂O at the 3.3–3.6 μm wavelength region. The spectra in this region contain the symmetric and antisymmetric CH₂ and CH₃ absorption, which can be used to monitor changes in the cells or the cell membranes. To demonstrate the performance and possible use of the system, IR analyses were conducted on three mammalian cell lines: Madin-Darby canine kidney (MDCK), rat basophilic cells (RS-ATL8), and aneuploid immortalized keratinocyte cells of adult human skin (HaCaT). The determination of the CH₂ and CH₃ absorption peaks allowed in vitro differentiation of the mammalian cell types. Successive viability tests showed normal cell proliferation in culture medium after incubation in D₂O-PBS for 30 min. The IR spectra of fifteen separate measurements showed only small absorbance tolerances, which proved the high level of repeatability of the sensor system. This measurement system opens up the way to perform infrared cell analysis in liquid environments.