Choosing an automated western blot machine: what a capillary automated western blot system measures that a western blot gel and membrane does not, where the reproducibility gain is real, and the sample and antibody constraints that come with it

Deciding whether it fits

1. Understand what the output actually is. A capillary system reports a signal against apparent molecular weight as a trace, with the band image reconstructed for familiarity. That makes quantification straightforward and makes some judgements a person makes by eye on a membrane, such as recognising a smear, harder.
2. Check your antibodies transfer to the format. Not every antibody that works on a membrane works in a capillary. The chemistry and the matrix differ, and each antibody has to be re-titrated and sometimes replaced. Budget that revalidation into the purchase rather than assuming the panel carries over.
3. Match it to small, precious samples. The strongest case is very small input: a few microlitres of lysate per run makes the format attractive for rare cells, biopsies and microdissected material where a conventional blot is simply not possible.
4. Be realistic about throughput and cost per sample. A run processes a fixed number of capillaries in a few hours and the consumable cost per sample is substantially higher than a gel. For a laboratory running many samples of one abundant target, a gel remains cheaper.
5. Keep the loading control question in view. The same normalisation argument applies here as on a membrane: a housekeeping protein has to be genuinely invariant, and total protein normalisation is available on these systems and is frequently the better answer.

Validating a transfer from gel to capillary

Run the same lysates both ways across a concentration series and compare the apparent size, the linear range and the effect you are trying to measure. Apparent molecular weight often differs between the two formats, which alarms people who were not expecting it.

Expect the linear range to differ too. Establishing it on the new platform is a day's work and it is what makes the quantification claim real.

Consumables and lock-in

Capillary cartridges and reagent kits are proprietary, so the cost per sample is fixed by the vendor for the life of the instrument. Model five years of your real sample numbers before the purchase.

Ask about cartridge lot variation and whether lots are reserved on request. On a quantitative platform, a lot change that shifts the signal is an investigation nobody budgeted for.

Where the reproducibility gain actually shows up

Between operators and between days, which is where conventional blotting is weakest. A laboratory with several people blotting the same target will see the largest improvement, and a single careful operator will see the least.

For multi-site studies the gain is larger again, because transfer efficiency is the variable hardest to harmonise between laboratories and the capillary format removes it entirely.

Common questions

What does an automated western blot system do differently?

It separates proteins by size in a capillary and performs immunodetection inside that capillary, reporting a quantified trace. There is no gel, no transfer and no membrane, which removes the two steps that cause most of the variability in a conventional blot.

Will my antibodies work on it?

Some will and some will not, and it has to be tested. Expect to re-titrate every antibody and to replace a proportion of them, and treat that as part of the setup cost.

Is it more sensitive than a conventional blot?

Often, particularly for small sample amounts, but the real gain is reproducibility and quantification rather than raw sensitivity. Claims of large sensitivity gains should be tested on your own lysates.

Should it replace conventional blotting entirely?

Rarely. Most laboratories that adopt it keep gels for screening, for large sample numbers and for anything where seeing the whole lane matters, and use the automated system where quantification or sample scarcity drives the work.

Browse by service class

• Compare Gene synthesis on advertised prices