Biomedical Engineering Reference
In-Depth Information
Pore
size
(µm)
Membrane type
Description
Ligand
Sulfonic acid (S)
Strong acidic cation
exchanger
R-CH
2
-SO
3
-
> 3
Quaternary ammonium (Q)
Strong basic anion
exchanger
R-CH
2
-N
+
(CH
3
)
3
> 3
Carboxylic acid(C)
Weak acidic cation
exchanger
R-COO
-
> 3
Diethylamine (D)
Weak basic anion
exchanger
R-CH
2
-N(C
2
H
5
)
2
> 3
Phenyl
Hydrophobic
interaction (HIC)
Phenyl
> 3
IDA
Metal chelate
Iminodiacetic acid
> 3
Protein A
Affinity
Protein A
0.45
Epoxy-activated
Coupling
Epoxy group
0.45
Aldehyde-activated
Coupling
Aldehyde group
0.45
Source:
Sartorius-Stedim
A special advantage in the use of membrane adsorbers is the removal of
high-molecular-weight contaminants such as DNA and viruses in mono-
clonal antibody manufacturing. Such molecules do not readily diffuse into
the pores of traditional resins; thus, most polishing steps relying on column
chromatography require dramatically oversized columns. These hydrody-
namic benefits provide the opportunity to operate the membrane adsorber
at much greater flow rates than columns, considerably reducing buffer con-
sumption and shortening the overall process time by up to 100-fold.
Sartorius-Stedim recently introduced single-use, disposable anion-
exchange membrane adsorption cartridges that can be used for DNA and
host cell protein removal or viral clearance. Likewise, Pall Corporation
offers a similar disposable membrane product specifically designed for DNA
removal. Other companies including GE Healthcare, Millipore, BioFlash
Partners, and Tarpon Biosystems have developed prepacked and presani-
tized disposable-format chromatography columns. Most of these columns
were designed for polishing applications, except Tarpon's, which can be also
be used for the capture step in monoclonal antibody (mAb) purification.
Capture of target remains a major challenge and contributes to the down-
stream bottlenecks plaguing many mAb manufacturers.
Virus Removal
Virus contamination is a risk to all biotechnology products derived from
cell lines of human or animal origin. Contamination of a product with
