Features

• < 10 minute ELISA

• With antibody-coated beads:

1. mix in tubes or micro-plate,
2. dispense in GRAVI™- Chip,
3. pipette the enzyme substrate,
4. allow 1 minute time for readout.

Benefits

• Flexibility: Bead-based protocols are easily adapted for rapid processing of most any available assay

• Cost-efficiency: Minimal reaction chamber volume implies >10-fold reduction in ELISA kit reagent consumption which, with chip regeneration convenience, results in most competitive data- point pricing

ELISA protocols

Three of immunoassay were developed, i.e.:

• A one-step method, in which coated micro- beads, sample and detection antibody are pre- incubated (in tube), and only thereafter introduced into the micro-channel.

• A two-step method, in which a pre-incubated mix of coated micro-beads and sample is introduced first, and detection antibody afterwards (upon pre- concentration of beads within the micro- channels).

• A three-step method, in which coated micro- beads, sample and secondary antibody are sequentially flown through the micro-channels, without prior incubation step.

Assay principle: Bead-based assay

GRAVI^TM- Chip is a device for performing ELISA tests following super-paramagnetic beads (magnetic core with a polymer matrix coating). These micro-beads are ideal as solid support for ELISA, because of the high reactive-surface to volume ratio. As a prerequisite to capturing the protein of interest, beads are simply coated with the desired antibody.

Coated beads, introduced in the micro-channel inlet, accumulate nearby the electrode surface by virtue of a magnet array. Solutions and reagents are sequentially flown through the micro-channels, until enzyme substrate is added for in situ signal detection. Upon readout, the magnet array is flipped away, beads are removed by addition of regeneration buffer, and the so-regenerated GRAVI^TM- Chip is ready for the following series of assays.

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