Optical noninvasive on-line monitoring and controlling system based on NIR absorption spectroscopy for glucose measurement of cell culture media in rotary cell culture system

Current techniques for monitoring glucose concentration during cell culture are invasively performed using an off-line measurement system. Even though in situ or ex situ analyte sensors have been tried for on-line measurement, they suffer from difficulties including the ability to keep them sterile, limited lifetime, and lack of stability. In this research an alternative, optical noninvasive on-line monitoring system based on near-infrared (NIR) absorbance spectroscopy was developed to measure glucose concentration of cell culture media in a rotary cell culture system (RCCS). The system included an automatic sampling component controlled by a LabView program and a high-throughput fiber coupling component connected to a Fourier transform infrared (FTIR) spectrometer. The effectiveness of the system was investigated via noninvasive on-line measurement of glucose absorbance spectra in the cell culture media during T-cell culture. Glucose absorbance spectra were collected in the spectral range of 2.0 to 2.5 μm. Partial least squares (PLS) regression was employed to build a successful multivariate calibration model. The standard error of prediction (SEP) and mean percent error (MPE) for glucose were 7.7 mg/dl and 1.0%, respectively. The successful results represent an important step in the development of a noninvasive, closed-loop, system for monitoring analytes in cell culture.; In order to replace the current FT-IR spectrometer for spectrum acquisition, a solid-block FT-IR spectrometer was also developed with the advantages of no moving parts and compactness compared to the commercial FTIR spectrometer. In the current system, the achievable maximum resolution was 12 cm −1. However, practical spectral resolution achieved was 71 cm −1 due to the limitations of other optical components, especially the Glan-Taylor polarizer that caused an unwanted interference and non-inform background on the real fringe image. The current resolution was enough to resolve the absorption peaks of glucose and serum solution to show the potential of the spectrometer. Absorbance spectra of glucose and serum solutions were acquired with this spectrometer and compared to the FTIR spectrometer.