Exploring cellular metabolic kinetics through spectroscopic analysis of extracellular environments

Studying the kinetics of metabolic pathways, such as glycolysis and glutaminolysis, is valuable due to their fundamental links to various diseases, including cancer. This study explores the potential of Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy for analysing low concentrations of metabolites in extracellular media. It also evaluates the use of the Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) method to data mine the kinetic evolution of the spectroscopic signatures of the glycolysis metabolic pathway and to explore the impact of the presence of glutamine on it. By extracting samples at specific time intervals and drying them on the ATR crystal, ATR-FTIR could effectively measure individual metabolites of glucose, glutamine and lactate at low concentrations, providing clear spectra with strong correlations between peak absorbance and metabolite concentrations. In data mining, MCR-ALS successfully resolved two components, glucose and lactate, from time-series data of cellular glucose metabolism (glycolysis), showing approximately 28 % glucose consumption and 1 mM lactate production at a constant rate of 0.0016 min^-1. However, when glutamine was introduced as a third component, the overlap of the peaks of glutamine and lactate limited the method's ability to deconvolute the data, highlighting constraints of MCR-ALS in complex mixtures.