Advances in DNA biology, particularly those of the past three decades, catalyzed the emergence and expansion of experimental approaches to manipulate gene expression. Subsequently, these advances impacted protein science, a field that found itself increasingly positioned at the juncture of technology, science, and art.
A fundamental prerequisite for generating any construct, as part of cloning and protein engineering efforts, regardless of the experimental system, is the ability to grow cultures under controlled and reproducible conditions. Process scouting devices, which most frequently are disposable devices such as shake flasks, spinner flasks, or microtiter plates, are routinely used in research at the earliest stages of bioprocess development. One of their disadvantages is that they are not equipped with sensors.
Although temperature and agitation are the most frequently measured variables in experiments performed in these devices, critical culture parameters, such as pH, oxygen level, and carbon dioxide level, cannot be accurately and safely monitored. This is partly because conventional probes are often costly and difficult to use. Nevertheless, many processes that are foundational to large, industrial-scale experiments, such as the generation, testing, and selection of clones, are performed early in bioprocess development, making it necessary to collect real-time experimental information on additional parameters. Moreover, inadequate monitoring can also hinder the subsequent integration of the parameters from various stages of an experiment, when protein expression is scaled up or down.
“We are trying to make bioprocessing more intelligent and provide a greater degree of measurement at all stages,” said Govind Rao, Ph.D., professor of chemical, biochemical, and environmental engineering and director of the Center for Advanced Sensor Technology at the University of Maryland, Baltimore County (UMBC). A major effort in Dr. Rao’s lab is focused on developing noninvasive, disposable sensors to actively monitor culture parameters during growth.
“Most biological processes are very complex, and many parameters change during the growth of a culture,” added Dr. Rao. Recently, Dr. Rao and colleagues described the use of triple disposable noninvasive optical sensors that can be positioned inside culture flasks, and revealed that pH, oxygen level, and carbon dioxide level can be dynamically monitored during E. coli fermentation to collect information that would not be routinely available from shake flasks.
According to a paper co-authored by Dr. Rao in Biotechnology Progress in 2012, the sensitive element of the disposable noninvasive optical sensors is a thin, luminescent patch affixed inside the flask. The paper also noted that small electronic devices for excitation and fluorescence detection are positioned outside the shake flask for noninvasive monitoring.
This work marked the first time disposable noninvasive sensors were used to measure dynamic changes in these parameters, over time, in shake flasks. “We have now started working on next-generation technologies, and our goal is to bring the whole bioprocess to the bedside or to the point of care, and take personalized medicine to a potentially different level,” said Dr. Rao.
Next-generation bioprocessing technologies target expression of biologics on demand, and there is a DARPA-sponsored effort under way at UMBC. “These efforts are paving the way toward next-generation bioprocessing, in which very well controlled protein expression can be performed at a small scale, in compact and low-cost systems, promising to change the entire biomanufacturing paradigm,” said Dr. Rao.