A model system and chemometrics to develop near infrared spectroscopic monitoring for Chinese hamster ovary cell cultivations

摘要

Near infrared (NIR) spectroscopy is an ideal tool for biopharmaceutical process monitoring, as it can be used to generate information on key bioprocess variables rapidly online. Mammalian cell cultivation is a rapidly developing field of biopharmaceutical production where one of these key process variables is the glucose concentration. However, calibrations for the NIR-based monitoring of glucose are usually not available in the early phase of process development owing to the lack of sufficient NIR data from small-scale experiments. This article demonstrates the development of calibrations based on NIR spectroscopy (11,988.0-4297.0 cm(-1)) for the determination of glucose concentration in a novel shake flask model system for mammalian cell cultivation. To generate a homogeneous distribution of glucose concentration in the calibration range and to reduce the correlation between glucose and other metabolites, cultivation samples with low glucose levels were spiked with glucose, and NIR measurements were subsequently performed. Biochemical and physical variability was deliberately induced in the model system to mimic possible matrix effects typically occurring in fed-batch bio-reactor cultivation samples. The specificity of the calibration model to glucose was increased by variable selection, so the spectral region between the two water peaks was used for calibration. Four mathematical pretreatments were evaluated by comparing the root-mean standard error of prediction (RMSEP) values of the models; the best preprocessing method was a novel combination of baseline offset method with the deresolve function. Our models predicted the glucose concentration in two test cultivations with an RMSEP of 3.12 mmol L-1 and 5.51 mmol L-1.