Current techniques used to monitor glucose concentration of cell culture media (CCM) require invasive and tedious handling of the sample for sterile media removal and nutrient replacement. In order to optimize cell culture growth in bioreactors, biosensors must be developed that are capable of monitoring the cell culture processes noninvasively and continuously. In this study, on-line, noninvasive determinations of glucose in cell culture media were investigated via near-infrared spectroscopy (NIR) across the 2.0-2.5 μm combination region. A system was developed, using a unique fiberoptic coupling method and a commercial Fourier transform infrared (FT-IR) spectrometer, to characterize glucose single-beam spectra collected from cell culture media. This novel system is the first of its kind and integrates a completely noninvasive optical probe to measure glucose concentrations within cell culture media, in situ. Spectra recorded from a four-day fibroblast culture with this fiber coupled system and an FT-IR spectrometer have been analyzed and compared with standard clinical chemistry techniques. Partial least-squares (PLS) regression has been used to extract the analyte-dependent information and to build a successful multivariate calibration model. A combination of spectra from cell culture media and prepared media mixtures was used to eliminate unwanted correlations in the calibration data. The combined use of this unique fiber-optic system, PLS, and uncorrelated spectra resulted in a true glucose prediction error of 14.8 mg/dL in an independent validation set.
Christopher B. Lewis, Roger J. McNichols, Ashok Gowda, and Gerard L. Coté, "Investigation of Near-Infrared Spectroscopy for Periodic Determination of Glucose in Cell Culture Media in Situ," Appl. Spectrosc. 54, 1453-1457 (2000)