Cell-based sensors and assays have great potential in
bioanalysis,
drug discovery screening, and biochemical mechanisms research. The
cell viability tests should be fast, safe, reliable, and time- and
cost-effective. Although methods stated as “gold standards”,
such as MTT, XTT, and LDH assays, usually fulfill these assumptions,
they also show some limitations. They can be time-consuming, labor-intensive,
and prone to errors and interference. Moreover, they do not enable
the observation of the cell viability changes in real-time, continuously,
and nondestructively. Therefore, we propose an alternative method
of viability testing: native excitation–emission matrix fluorescence
spectroscopy coupled with parallel factor analysis (PARAFAC), which
is especially advantageous for cell monitoring due to its noninvasiveness
and nondestructiveness and because there is no need for labeling and
sample preparation. We demonstrate that our approach provides accurate
results with even better sensitivity than the standard MTT test. With
PARAFAC, it is possible to study the mechanism of the observed cell
viability changes, which can be directly linked to increasing/decreasing
fluorophores in the cell culture medium. The resulting parameters
of the PARAFAC model are also helpful in establishing a reliable regression
model for accurate and precise determination of the viability in A375
and HaCaT-adherent cell cultures treated with oxaliplatin.