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Antibody titer and active concentration, on one label-free method

Titer, potency, and comparability are usually three assays on three platforms, each with its own standard curve and its own reagents, and none of them transfers cleanly to the next stage.
Up to 768 samples on the inQuiQ768
Affinity range from 10 pM to 10 mM
From 30 µL of sample per injection

Where process and QC scientists use label-free binding analysis

Label-free interaction analysis measures real-time binding of unmodified molecules, enabling active concentration, binding kinetics, and batch-to-batch comparability without labels or secondary antibodies.

Upstream titer

Track antibody titer through the bioreactor run.

Measure straight from clarified cell culture supernatant.

cell culture supernatant

Clone and cell line selection

Rank clones on what they actually produce.

Compare titer and binding activity across candidate lines.

clone selection

Downstream monitoring

Follow the product through capture and polishing.

Check binding activity after Protein A, ion exchange, and SEC.

Protein A capture

Potency and identity

Confirm the product still engages its target.

Active concentration reports function, not total protein mass.

active concentration

Biosimilarity and comparability

Run candidate and reference standard on the same chip.

Compare kon, koff, and KD side by side across lots.

reference standard

Benefits of the inQuiQ in bioprocessing

01 / 04

One injection, four channels, sixteen sensors

Four independently addressable flow channels, each carrying four sensors, with the sample flowing through the channels in series.

30 µL minimumsequential flow paths
In-flow immobilisation
Spotter immobilisation

Run a plate of batches without touching it

The inQuiQ768 autosampler takes 2×96 or 2×384 well plates and injects one sample after another. Samples run in series, so every batch meets the same surface under the same conditions.

2×96 wells2×384 wells
one plate, sequential injections

Measure what still binds, not just what is there

A standard curve of the reference material turns binding response into active concentration. Total protein mass counts everything in the sample; active concentration counts only what engages the target.

standard curvepotency
response read against a standard curve

Put the reference standard next to the lot

Immobilise the reference material alongside candidate lots and inject once. Up to sixteen targets and controls are read from a single spotted chip, so comparability comes from one run.

reference standard
in trend
lot A
in trend
lot B
shifted
16 sensors (spotter required)one injected sample
reference and lot, same axes

How a binding run works

Every measurement follows the same steps, whatever the stage. A capture ligand is held on the sensor, the sample flows past, and the response is recorded through the whole injection rather than at the end.

Ligand immobilisation

The capture ligand goes on the sensor surface first.

For antibody titer and active concentration assays, Protein A, the antigen, or a receptor is coupled once and the same surface then serves every batch. Ligand density is set low enough that titer readings are not limited by transport to the surface.

  • Protein A
  • capture ligand
  • ligand density

Deactivation

Unused activated sites are switched off before the first supernatant arrives.

Cell culture supernatant carries host cell protein and media components. Deactivation, together with the antifouling hydrogel, keeps those out of the sensorgram as non-specific binding.

  • deactivation
  • host cell protein
  • non-specific binding

Association

The sample flows across the surface and the response climbs.

In bioprocessing kinetics analysis the association phase gives kon and, read against a standard curve, the active concentration of product in the sample. Supernatant is clarified through a 0.22 µm filter before injection.

  • active concentration
  • standard curve
  • kon

Dissociation

Buffer replaces the sample and the response falls as the complex comes apart.

The dissociation phase gives koff, and kon with koff gives KD. Comparing those three numbers lot to lot is how potency, identity, and biosimilarity are tracked from upstream through release testing.

  • koff
  • KD
  • potency
  • comparability

Regeneration

A regeneration buffer returns the sensor to baseline for the next batch.

The capture ligand stays in place, so every lot and the reference standard meet the same surface. On the inQuiQ768 a full plate of batches runs unattended.

  • regeneration
  • reference standard
  • unattended runs
Response (RU) Time

What the inQuiQ does for bioprocessing

Six capabilities, one modular benchtop instrument, in a label-free workflow.

Many lots, one prepared surface

Four channels with in-flow immobilisation, or sixteen sensors with a spotter, put batches and controls on the same capture surface.

16 sensors (spotter required) 30 µL

Active concentration, not total mass

A standard curve of the reference material turns binding response into the concentration of product that still engages its target.

standard curve

Clean signal from crude supernatant

The antifouling hydrogel keeps host cell protein and media components out of the trace, with samples filtered through 0.22 µm.

0.22 µm filter

Reference standard side by side

Candidate lots and the reference material sit on one chip and meet the same injected sample, so comparability is read from one run.

biosimilarity comparability

The same kinetic method at every stage

kon, koff, and KD are measured the same way upstream, downstream, and at release, so the numbers compare across the process.

kon, koff, KD

Unattended runs on the inQuiQ 768

The autosampler takes 2×96 or 2×384 well plates and works through them one injection after another.

2×96 wells 2×384 wells
Start A conversation

Talk to an application scientist

Bring your process step. We will tell you honestly whether label-free is the right method for it, and how the assay would be built.

Ready to see the inQuiQ in action?

Questions researchers ask

Immobilise Protein A or the antigen on the sensor, inject clarified supernatant, and read the binding response against a standard curve of the reference material. No secondary antibody and no label is needed, and the result is the concentration of antibody that still binds rather than total protein mass.

Run a dilution series of a reference standard to build the curve, then inject the unknown sample under the same conditions and read its response across. Because only material that engages the immobilised ligand contributes signal, the number reports functional product, which is what potency assays need.

Usually yes, after clarification through a 0.22 µm filter. The antifouling hydrogel surface limits binding by host cell protein and media components, and a reference channel subtracts what remains. That removes a purification step between the bioreactor and the number.

Put both on the same chip and inject the same sample series. Measuring kon, koff, and KD side by side under identical conditions makes the comparison a single experiment rather than two runs that have to be normalised against each other afterwards.

The inQuiQ768 autosampler holds 2×96 or 2×384 well plates and works through them one injection after another. Samples run in series, never in parallel, so every batch meets the same prepared surface under the same conditions across the sequence.