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.

 

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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)

 

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 an hour, the assembly should be stored in a refrigerator (4–10 °C).

 

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Planning the cartridge layout

You can process 1 to 96 cartridges with immobilized substrate in parallel. The Bravo robot moves as if 96 cartridges are being used regardless of the actual number of cartridges present. The Bravo robot applies differential pressure to seat cartridges on the probes of the head based on the number of full columns of cartridges being processed. To ensure proper cartridge seating on the head, arrange the cartridges in full columns.

For runs of fewer than 96 cartridges:

•	Arrange the cartridges in multiples of 8 in a column-based configuration.

•	If the number of cartridges to be processed are not a multiple of 8, use the AssayMAP Resin-Free cartridges to fill in the partial column, as the following figure shows.

Using the Resin-Free cartridges to fill a partial column prevents liquids from dripping on the deck or being dispensed on the deck during the Cup Wash steps.

Figure. Example of cartridge layouts in the Cartridge & Tip Seating Station

 

The positions of the cartridges at deck location 2 dictate the positions of the solutions in deck locations 3, 4, 5, 6, and 8.

 

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