ProteOn XPR36, User Manual

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Experiment Preparation
65
and in some instances may actually decrease ligand immobilization or
interfere with interspot referencing).
Preparing the Buffers
Note: Running buffers not purchased from Bio-Rad should be
filtered through a 0.22 μm filter.
For most applications, buffer solutions should contain salt and surfactant to
minimize the adsorption of proteins to the microfluidics tubing and the MCM
channels. Surfactant may be omitted if the sample or interaction is detergent-
sensitive. For DNA-protein interactions, a chelating agent such as EDTA is
added to remove any metal ions that might interfere with the interaction. The
ProteOn XPR36 microfluidics system contains an in-line degasser. It is not
necessary to degas the buffer solutions before use.
The recommended buffer is ProteOn PBST (PBS with 0.005% Tween 20) for
most applications on the ProteOn XPR36 instrument. ProteOn PBS buffer is
available prefiltered in 2 L bottles that can be used directly as buffer
reservoirs. PBS with 0.005% Tween 20 (PBST) and 3 mm EDTA (PBSTE) is
also available.
To prepare the buffers:
1. If you are using buffers not purchased from Bio-Rad, filter the running
buffer through a 0.22 μm filter.
2. Place the buffer bottle(s) in the buffer compartment and attach the
tubing-fitted screw caps.
Always rinse the buffer filters in distilled deionized water between bottle
changes to prevent cross-contamination.
Loading the Buffer Solution
Two different buffers can be loaded in the system, one in buffer bottle A and
one in buffer bottle B. The following procedure assumes that the instrument is
in Standby state and a maintenance chip (or a sensor chip from a previous
experiment) is loaded in the instrument.
To load the buffers:
1. Remove a 2 L bottle of running buffer (for example, ProteOn PBST, pH
7.4) from the refrigerator.
2. Take approximately 15 ml of the buffer, place it in a 50 ml conical
centrifuge tube, and place the tube on ice for sample preparation.