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Saturday, January 26, 2013

Millipore SNAP i.d. protein detection system

SNAP i.d. is a vacuum-driven apparatus to block, stain and wash your Western blots. It promises to shorten your time to as little as 30 minutes from the moment you finish your transfer to the moment you are ready for detection. It's definitely a significant improvement from almost 24 hours.

The concept is simple you put your membrane in a special cassette which allows even distribution of liquids, you first put the block on top and the vacuum sucks it through, then you continue with the primary antibody, etc. Blocking takes the time for 30ml of solution to flow through the system and antibody stainings which are done in 3 mL of liquid are 15 minutes. Washes are immediate. There is even a little plastic collector you can put under the cassette to recover your antibody, if you wish.

Does it work? Yes. We were really on the fence on whether we wanted to buy it. At $1,500 it is not cheap, but would it provide such huge time savings to be worth the price? If you are a biochemistry lab working on a finite set of antibodies and repeating the same assays over and over again, absolutely. We calculated the cost per run and since the antibody itself is the most expensive fraction of the cost, the $2 per cassette is quickly compensated by having to use less total antibody (though they recommend 3X concentration). At the end the cost per run is the same with traditional methods than with the SNAP i.d. In addition, cassettes can be reused a few times for the same antibody which would make it even cheaper.

Scilogex Analog Tube Roller
The problem is optimization. Every antibody must be optimized as far as concentration and incubation time. Reviews on the internet (here and here) indicate that sometimes you cannot skip the usual overnight primary incubation because the fast antibody absorption just doesn't work and that you have to play with the antibody concentration because of reduced sensitivity. One possibility we considered is to use it just for secondaries, which would shorten the washes-secondary-washes portion to 20 minutes instead of 3 hours.

As a new lab, I decided to pass for the moment because the upfront cost and the cost of consumables does not justify the expense. Instead we bought a Scilogex tube roller, which cost around $250, so that we could incubate our primaries in rolling Falcon tubes instead of shaking plastic cassettes cutting down the antibody solution to 2-3mL at the usual concentration, which saves us from using the 3X concentration required from the SNAP i.d. And the thing about the tube roller is that you can use it for a lot of other things. One day when I am rich, I'll buy a SNAP i.d.

Remember to look at the Lab-things we like page for more products and reviews.

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