The laboratory isn’t a safe place for experiments anymore
By now, most have heard that Bisphenol A, a toxic compound important in the production of polycarbonates, can leach out of plastics into the contents of said-polycarbonate container, especially when heated. Therefore, should a recent Brevia in Science be any surprise?
Apparently, the authors have identified two processing additives in otherwise “sterile” polycarbonate tubes that are bioactive and, in fact, ruining their experiments.
They were looking at the in vitro activity of the enzyme hMAO-B and found that water washed through common polycarbonate tubes acquired the potency to inhibit the enzyme. When common solvents like DMSO or methanol were used, the inhibition became even more pronounced.
The effects were also seen when assays were conducted using 96-well plates. But the scariest result? The extraction of the inhibitory “leachates” could occur even after repeatedly pipetting up and down using a disposable pipette tip!!! I know I certainly mixed the contents of a tube more than once using the old “up and down” pipette method.
Testing the effects in a completely independent assay, the authors also found that the leached chemicals could inhibit the binding of radio-ligands to GABAA receptor-containing membranes. So this wasn’t something only specific to some enzymatic reaction, but also to ligand-receptor binding relationships! Yowsers!!
As if scientists didn’t have enough to worry about, now there is a chance that sterile plasticware is autonomously inhibiting your enzymes and blocking your receptors. Almost all experiments involve dipping a plastic pipette tip into a small plastic tube containing some aqueous goo or chemical goody, so this warning is not simply relevant for the biochemists who love to work in containers. However, the effect is likely to be diminished outside of the tube once the “leachates” are further diluted. Nevertheless, these are issues that should be kept in mind.
Meanwhile, the manufacturers are shocked by the news, with Eppendorf representatives quoted in a Nature news piece as saying:
So far, we have not experienced any product problems with our customers due to these substances.
Of course you haven’t boys, of course you haven’t.
For those of you out there using enzymes or conducting receptor-ligand experiments, I would be interested to hear your results after conducting a simple experiment to replicate these findings in your system. If true, and you are one of the many potential experimentalists afflicted by this problem, it would be quite bittersweet news…
McDonald, G., Hudson, A., Dunn, S., You, H., Baker, G., Whittal, R., Martin, J., Jha, A., Edmondson, D., & Holt, A. (2008). Bioactive Contaminants Leach from Disposable Laboratory Plasticware Science, 322 (5903), 917-917 DOI: 10.1126/science.1162395