394
B. Igne and E. W. Ciurczak
in how models can be made more robust, reducing the need for updates, or streamlining the updates, or applying re-calibration/re-validation approaches to ensure these
methods are ready with minimal to no downtime [17].
18.3 Large Molecules
The manufacturing of biologics (i.e., monoclonal antibodies, recombinant proteins
and DNA, vaccines, etc.) relies on complex cellular systems with high sensitivity
to their environment and feeding regimen. The production of large molecules by
microbes and mammalian cells requires the control of numerous processing parameters such as nutrient concentration, temperature, pH, gases, agitation, etc. The
host cells, the product, the by-products (lactate, ammonium, CO 2 , etc.), and the
growth medium constitute a complex mixture with many of the chemical species
present in a bioreactor at levels undetectable by many analytical tools, including
NIR spectroscopy.
The production of large molecules typically follows a two-step process: first the
microorganisms produce the molecules of interest, then the molecule is purified from
the growth medium, cells, viruses, and other impurities. However, to date, much of the
published work involving NIRS has been to produce large molecule in bioreactors.
The manufacturing process heavily relies on the in-line and in real-time measurements and control of processing parameters such as pH, dissolved oxygen, dissolved
CO 2 , and other elements impacting cell health. Depending on the desired feeding
strategy, nutrients (i.e., glucose) may need to be measured and controlled throughout
the duration of the batch and by-products (i.e., lactate, ammonia) may also need
to be monitored. However, their measurements have been and remain a challenge.
As a consequence, manual sampling and off-line measurements with fundamental
primary analytical methods are still predominant. Nevertheless, the use of in-line
spectroscopy as a process analytical tool to monitor and control these bioreactors
has seen a significant increase over the last decade. While Raman spectroscopy may
appear to be better suited to a water rich process, near-infrared spectroscopy has been
widely utilized [18].
18.3.1 Bioreactor Monitoring and Control
Initially employed for the analysis of pulled samples at-line or off-line, it is now
commonly used on-line through a recirculation loop or in-line with a probe directly
introduced in the bioreactor.
The first report of the use of off-line spectroscopy was performed on a fermentation
process for A. awamori and P. oxalicum [19] at 1L scale.
Further work was performed for the analysis of the yeast fermentation processes
for the production of mammalian proteins. A significant body of literature exists
B. Igne and E. W. Ciurczak
in how models can be made more robust, reducing the need for updates, or streamlining the updates, or applying re-calibration/re-validation approaches to ensure these
methods are ready with minimal to no downtime [17].
18.3 Large Molecules
The manufacturing of biologics (i.e., monoclonal antibodies, recombinant proteins
and DNA, vaccines, etc.) relies on complex cellular systems with high sensitivity
to their environment and feeding regimen. The production of large molecules by
microbes and mammalian cells requires the control of numerous processing parameters such as nutrient concentration, temperature, pH, gases, agitation, etc. The
host cells, the product, the by-products (lactate, ammonium, CO 2 , etc.), and the
growth medium constitute a complex mixture with many of the chemical species
present in a bioreactor at levels undetectable by many analytical tools, including
NIR spectroscopy.
The production of large molecules typically follows a two-step process: first the
microorganisms produce the molecules of interest, then the molecule is purified from
the growth medium, cells, viruses, and other impurities. However, to date, much of the
published work involving NIRS has been to produce large molecule in bioreactors.
The manufacturing process heavily relies on the in-line and in real-time measurements and control of processing parameters such as pH, dissolved oxygen, dissolved
CO 2 , and other elements impacting cell health. Depending on the desired feeding
strategy, nutrients (i.e., glucose) may need to be measured and controlled throughout
the duration of the batch and by-products (i.e., lactate, ammonia) may also need
to be monitored. However, their measurements have been and remain a challenge.
As a consequence, manual sampling and off-line measurements with fundamental
primary analytical methods are still predominant. Nevertheless, the use of in-line
spectroscopy as a process analytical tool to monitor and control these bioreactors
has seen a significant increase over the last decade. While Raman spectroscopy may
appear to be better suited to a water rich process, near-infrared spectroscopy has been
widely utilized [18].
18.3.1 Bioreactor Monitoring and Control
Initially employed for the analysis of pulled samples at-line or off-line, it is now
commonly used on-line through a recirculation loop or in-line with a probe directly
introduced in the bioreactor.
The first report of the use of off-line spectroscopy was performed on a fermentation
process for A. awamori and P. oxalicum [19] at 1L scale.
Further work was performed for the analysis of the yeast fermentation processes
for the production of mammalian proteins. A significant body of literature exists