Preparing cartridges with immobilized substrate
How to prepare the cartridges
The On-Cartridge Reaction app facilitates reactions between a substrate immobilized on a cartridge and a soluble reactant. The cartridges containing the immobilized substrate are prepared before the On-Cartridge Reaction run using any of the other AssayMAP applications, typically, Affinity Purification.
How to store prepared cartridges
Do not allow cartridges with immobilized substrate to dry out. If the cartridges do dry out, do not use them. To avoid cartridges drying out, store them immediately after the Affinity Purification run in an AssayMAP cartridge rack and receiver plate assembly, where each chimney of the receiver plate housing a cartridge with an immobilized substrate contains 200 µL of buffer. Use a buffer that is known to be compatible with the cartridge’s immobilized substrate and resin.
Figure AssayMAP cartridge rack lid (1), rack with cartridges (2), and receiver plate (3)
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Using this storage method, the tip of the cartridge is submerged in a buffer and prevents the cartridge bed from drying out. Place the lid on the cartridge rack and receiver plate stack to prevent anything falling into the cartridges. For storage longer than a few hours, the assembly should be stored in a refrigerator (4–10 °C).
Planning the cartridge layout
You can process 1 to 96 cartridges with immobilized substrate in parallel. The position of the cartridges in the seating station dictates the position of the reagent and buffer solutions in the microplates at each deck location.
• If you have fewer than 96 cartridges, make sure the cartridges occupy full columns in the microplate, as the figure below shows.
The default protocol settings assume that cartridges will be arranged in multiples of 8 in a column-based configuration. Also, the AssayMAP Bravo Platform applies differential pressure to seat cartridges based on the number of full columns of cartridges. To achieve proper cartridge seating, entire columns must be used.
• If the number of cartridges you have is not a multiple of 8, use AssayMAP Resin-Free cartridges to fill the empty well positions. This will prevent liquids from dripping on the deck or being dispensed on the deck during the Cup Wash steps.
Figure Examples of microplate and reservoir layout: A) Multiple of 8 samples, B) Not a multiple of 8 samples
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The positions of the cartridges at deck location 2 dictate the positions of the solutions in deck locations 3, 4, 5, 6, and 8. See Labware for the acceptable labware at each deck location.