Download Centrifugal Separation in Biotechnology

Centrifugal Separation in Biotechnology
Plenary Presentation
Wallace Woon-Fong Leung
Chair Professor of Innovative Products & Technologies
Department of Mechanical Engineering,
The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
email: [email protected]
Abstract:
Disk-stack and tubular centrifuges have been used to separate soluble and insoluble proteins for
biopharmaceutical processing. There are three common host-cell technology platforms, namely
yeast, mammalian cells, and bacteria. The first two use the host cells to express extracellular
protein, while the latter uses the host cell to express intracellular protein in form of submicron-sized
inclusion bodies.
For the yeast host-cell process, the first step is to separate yeast cells using centrifugation from
dissolved protein, followed by clarification of protein solution product using centrifugation to meet
the minimal turbidity requirement.
The flow sheet of separating mammalian cells such as Chinese Hamster Ovaries (CHO) cells using
centrifuge from the protein product is presented. The key concern is to reduce shear on the cells in
the suspension (maintain high cell viability) through gentle feed acceleration to high-speed rotation
to effect separation in a centrifuge. The subsequent step is to use a depth filter or microfiltration to
clarify the separated liquid product removing any submicron fine solids. It is critical to ensure the
centrifuge-filter work together as a system.
The flow sheet of processing bacteria bearing protein is to concentrate using centrifugation the
bacteria solution followed by lysing the bacteria to release the inclusion bodies. The resultant
suspension is reslurried and washed, with the protein-bearing inclusion bodies separated from any
impurities by centrifugation until the desired purity is reached suitable for downstream processing.
Separation by centrifugation is used extensively in these three host-cell platforms, which is a major
application in production of antibotics and intermediate drug substances for the biopharmaceutical
market.
Other important large-scale centrifugal separation in biotech processes has also been discussed.
Finally, throughput and sizing of centrifuge and simulation tools are presented.
Keywords: centrifugation, centrifuge, disk-stack, tubular, biopharmaceutical, biotechnology
Biography of Prof. Wallace Leung
Prof. Wallace Leung is Chair Professor of Innovative Products & Technologies at the Department of
Mechanical Engineering at The Hong Kong Polytechnic University, Hong Kong since 2005. He was
also Director of the Research Institute of Innovative Products & Technologies between 2005 and
2010 at the university during which he led a team of multidisciplinary experts to develop healthcare
and medical devices.
Prof. Leung started his filtration and separation career at MIT in the 70’s researching ultrafiltration
of protein and lamella sedimentation of slurry containing fine particles. For 6 years, he worked on
liquid flow in porous media, respectively, at Gulf Oil and Schlumberger. For 18 years, he led a
research team at Bird-Baker Hughes to develop solid-liquid separation technologies including
centrifugation and pressure/vacuum filters. He has covered areas including feed acceleration in a
centrifuge, sedimentation, cake compaction, effluent liquid discharge. Subsequently, he found
Advantech Engineering with focus on biotech separation and kaolin classification. He had
researched and successfully developed over 10 technologies and held 36 US patents and many
foreign patents on centrifugation. He has written two books Industrial Centrifugation Technology
(1998, McGraw-Hill) and Centrifugal Separation in Biotechnology (2007, Academic Press/Elsevier).
He was the Chairman of the American Filtration Society in 2000 and also the Chairman of the
INDEFI 2000-2004 responsible for organizing the 9th World Filtration Congress held in New Orleans
in 2004. His research interest is in centrifugal separation and classification of micron-sized particles
and centrifugal separation of biosolids. Recently, he is interested in small-scale rotating devices for
enhancing mixing and separation, as well as filtration of submicron aerosols. He received his BS
from Cornell, and MS and ScD from MIT all in Mechanical Engineering.