Mid-IR laser measurement of acetaldehyde in the headspace gas of cell culture media samples from growth of breast cancer cells in hydrogel scaffolds.

A mid-IR laser absorption spectrometer configured with an interband cascade laser (ICL) was used to measure acetaldehyde concentrations in the headspace gas of cell culture media samples obtained from the culturing of breast cancer cells in a flow perfusion bioreactor. Measurements were performed by bubbling lab air through a media sample and passing the exhaust gas through a long optical path gas cell where rotational-vibrational modes of acetaldehyde were excited by the ICL. Acetaldehyde concentrations were determined from peak-to-peak voltages for the two strongest acetaldehyde absorption features within a spectral region spanning 1770.20 cm^-1 to 1770.35 cm^-1. Three different media samples obtained from cells cultured with the same nominal conditions had headspace acetaldehyde concentrations of 412 ppb, 513 ppb, and 390 ppb, while two media samples with imposed hypoxia or cobalt chloride stabilization of hypoxia inducible factor 1-alpha (HIF-1α) had higher acetaldehyde concentrations, 815 ppb and 536 ppb, respectively. These results establish experimental proof-of-concept for the ability of mid-IR laser absorption spectroscopy to measure acetaldehyde in cell culture media headspace, allowing observation of HIF-1α driven shifts in cancer cell metabolism.