Membrane separations, lysate processing

To answer the above issues, a model system was devised in which a specific protein was added to ah IS. coll lysate. The lysate was then processed through the filtration steps and the protein recovered. The protein chosen was human IgG which has a relatively large molecular weight (160,000 Daltons). It was reasoned that if a large protein could be separated from cell debris and passed through a membrane and recovered, then a smaller protein that is typical of a recombinant process, should prove to be much easier. 

Quake and coworkers [16] developed a PDMS microfluidic device (shown in Eig. 4c) for nucleic acid purification from a small number of bacterial or mammalian cells. This multilayer device contained fluidic channels and a system of membrane-actuated pneumatic valves and pumps, which enabled precise control of buffers, lysis agents and cell solution, and also allowed for parallel processing. Bacterial cells, dilution buffer and lysis buffer are first introduced into the chip and then transferred into the rotary mixer. Once mixed, the lysate is flushed over a DNA affinity column and drained. The DNA is recovered from the chip with an elution buffer for further analysis. We note that this is the only microfluidic chemical C3flome-try device to use a separation method other than solution-phase electrophoresis (i. e., solid phase extraction). 

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