Investigation of near-infrared spectroscopy for periodic in situ cell culture media determination of glucose and lactate

Abstract

Current techniques used to monitor glucose concentration of cell culture media require invasive and tedious handling of the sample for sterile media removal and nutrient replacement. In order to maximize cell culture growth in bioreactors, biosensors must be developed that are capable of monitoring the cell culture processes non-invasively and continuously. Non-invasive determinations of glucose and lactate in cell culture media were investigated via near-infrared spectroscopy (NIR) across the 2.0-2.5 []m combination region. A system was developed using a Fourier Transform Infrared (FHR) spectrometer to characterize glucose and lactate single beam spectra collected from cell culture media. Spectra recorded from a three-day fibroblast culture using a fiber-optic coupled culture flask with an FTIR spectrometer have been analyzed and compared with standard clinical chemistry techniques. Partial least squares regression has been used to extract the analyte-dependent information and to build a successful multivariate calibration model. Calibration, using a combination of spectra from cell culture media and prepared media mixtures, was performed and applied to an independent validation set, resulting in a prediction error of 14.8 mg/dl. Critical parameters surround the application of NIR spectroscopy to most biologically based samples, such as cell culture media. In addition to temperature and humidity, pH stability plays an essential role in the investigator's ability to accurately quantify concentrations of analyses of interest. It has been shown here that absorbable spectra of glucose may drastically deviate from "normal'' in the presence of pH-varying sample and a pH-constant reference spectrum. Because cell culture ranges of PH extend beyond the comparatively tight control of human physiological pH, it was necessary to seek out these implications and report them. For quantification studies, results indicate that potential interference due to varying pH values must be accounted for.