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Bioprocessing Monitoring Continued from page 38 due to variability of liquid level (particularly in rocking bio-bags). Cost must be reasonable as well, since the probes are disposable. The Aber probes consist of four annular ring electrodes that monitor current and voltage inside the culture. In the absence of cells, current and voltage are in synch. Due to the nature of capacitance, as cell density increases, voltage and current become out of phase. Only living cells containing a conducting cy- toplasm enclosed with an intact nonconducting membrane are polarized under the electric feld, which is how RFI distinguishes between living and dead cells or debris. While it may be novel for bioprocessors, RFI detection is not a new technology. Many such systems are installed in breweries across the United States to allow accurate yeast dosing at the beginning of each fermentation. A team led by Lisa Graham, Ph.D., senior VP at Bend Research, is exploring the capabilities of using scanning multifrequency dielectric spectroscopy (SMFDS) to profle multiple bioreactor runs and quantify cell viability. Dielectric spectroscopy measures the capacitance, or charge-storing characteristics, of samples across a spectrum of frequencies. In the case of cells, this charging happens via a phenomenon known as Maxwell-Wagner polarization, which occurs because of the Color your lab nonconductive nature of cellular membranes. Dielectric spectroscopy takes advantage of this characteristic by treating electrical measurements from cells in media as if they were an electrical circuit. The number of capacitors (cells) and the properties of the dielectric comprising them (size, morphology, ion content, membrane composition) affect the shape of the dielectric spectrum and can, therefore, be measured. "Dielectric spectroscopy yields critical information about cell number, cell health and viability, metabolic changes, and morphology of different cell populations," Dr. Graham said. "The challenge is to link physical measurements of cell properties with the biological information we are after." To achieve this, the dielectric data must be viewed in the context of metabolite data. "Much of the development of dielectric spectroscopy—and Rapid, Reliable Sandwich-Type Assays MiniBio and my-Control: good looks, great performance Our colorful range of MiniBio bioreactor systems provides a true scale down of your laboratory scale bioreactors. The MiniBio systems have the same versatility as the laboratory scale bioreactors. This means that the MiniBio systems can be customized to fit your demands for any process. The small volume reduces medium costs and optimizes the use of expensive bench space. MiniBio and my-Control: colorful power for every lab • Microbial and Cell culture configuration • Batch, Fed-Batch and Continuous cultivation • True scale down design offers easy scale-up of processes • 250ml Total volume with up to 200ml working volume • pH, DO, Temperature, Level and Foam sensors • 500ml Total volume with up to 400ml working volume • Classical sensors for reliable and stable signals • 1000ml Total volume with up to 800ml working volume • Up to 6 variable speed pumps or micro valves • Borosilicate glass vessel and stainless steel head plate and inserts for additions • Gas Flow via optional Mass Flow Controllers • Overlay or Sparger aeration (L-sparger or porous sparger) • 5 Complete bioreactor systems on 1m bench space • Lipsealed stirrer for up to 2000 RPM mixing • Operation via web browser, iPhone, iPod and iPad • Height adjustable impellers (Rushton or Marine impellers) • Up to 32 parallel my-Controllers of processes • Software for parallel cultivations and data processing A STEP AHEAD www.applikon-biotechnology.com 40 | September 1, 2013 | GENengnews.com | Genetic Engineering & Biotechnology News Process analytic technology implementations have been slow to achieve real-time analysis and monitoring for high-level parameters such as protein titer and host cell contaminants. These critical parameters are typically analyzed by HPLC or sandwich-type assays, both of which are time consuming and, even in automated formats, prone to human error. Uppsala Sweden-based Gyros has introduced the Gyrolab™ xP, which miniaturizes, standardizes, and automates up to 112 sandwich assays and delivers results in about one hour. Gyrolab enriches monitoring from discovery through clone selection, media and process development, scaleup, and manufacturing. The system is based on an automated liquid-handling system that uses eight needles for sample transfer and two for reagents. Instead of running the assays in plates through sequential addition of reagents, the analysis cassette consists of a compact disk (CD) containing 112 microchanneled analysis pathways, including a 15 nL streptavidin bead column. After samples are introduced, the CD spins and samples move through the channels and column through centripetal force. When the assay is completed, a robotic arm moves the CD to a reader, which generates the result. According to North American marketing manager Joy Concepcion, Gyrolab provides significantly greater dynamic range (3–4 log) compared with traditional sandwich assays (about 1.5 log). "Traditional ELISA can take an entire day. Results that fall outside the assay's dynamic range can stretch the time out to a week. With Gyrolab, 90% of results fall within the system's detection capabilities, which translates to less re-work." n