Unchained Labs eBook - 24

Unleash your biologic * Kick manual buffer exchange to the curb

Junior and Grunt use a pressure-based, ultrafiltration/diafiltration
(UF/DF) methodology to perform the exchange of a protein from one
buffer to another (Figure 3). Gentle orbital mixing is performed during
pressurization, which decreases polarization at the membrane. In
addition, it reduces aggregation propensity, and improves the rate of
exchange and mass recovery, especially for high concentration samples.
Both Unchained Labs automated buffer exchange instruments
measure sample volume between exchange cycles. The operator can
also set the degree of buffer exchanged per cycle. These capabilities
enable total control over the buffer exchange process. If there is
concern about osmotic shock of the protein into the new buffer, a
lower exchange rate can be set per cycle. If osmotic shock is not a
concern, a higher exchange rate can be set per cycle. The total degree
of exchange can also be controlled. Faster exchange can occur if a
lower target exchange is selected, such as 96%. If the protein needs
to be exchanged more thoroughly, a higher target exchange
percentage can be set, up to 99.5% exchanged.
Figure 3.
Unchained Labs automated buffer exchange solutions use the
same UF/DF methodology in two different exchange formats:
Unfilter, a 96-well filter plate and Funl, a milliliter filtration cup.

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The volume check also provides a feedback loop during the process.
Since the target protein concentration and target exchange is known
at the start, the system will check the process as it proceeds. If the
solution viscosity is changing with formulation changes, the system
will recognize that change and adjust subsequent buffer additions
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