Earlier I made a post about decontaminating solutions and how to homebrew them for cheap. I had one more patent to talk about but I felt kinda burnt out (and a bit guilty that I was bullying the decontaminating solution manufacturers association (DSMA) so much ), I ended up letting it sit for a bit. But this horse isn’t quite dead yet, as I think there’s some very useful information to be gleaned by examining the solution known as DNA Zap, from Thermo.
It’s a bit of an oddity, a TWO part cleaning solution meant to destroy nucleic acids, which you apply to an area one after another. Pretty…how you say, le fancy, non? Taking a peek at the MSDS will tell you that Part A contains copper sulfate, which I hadn’t encountered in decontaminating solutions before. WHY??? WHY DO YOU NEED COPPER SULFATE??? What magic is in the mix that can possibly improve on your standard soapy/bleachy/NaOH-y goodness?
Go read the patent, titled “METHOD OF MAKING A FORMULATION FOR DEACTIVATING NUCLEIC ACIDS” it’s fascinating. It’s written in legalese, but the amount of figures/tables/DATA proving the efficacy of this mixture is astounding! Hats off to the people who did all the work, what a nice bit of optimizing 🙂 It’s a pretty neat little system they’ve thought up.
Part A consists of copper sulfate (2 mM) and hydrogen peroxide (3%). This solution in and of itself will destroy nucleic acids on contact. They do not comment on the mechanism on which this works, though. Interestingly, the peroxide based inactivation has similarities to patents by Qiagen and the University of Montreal, which we covered in the last article.
Part B is a pH 9.3 solution of 0.6% hypochlorite (so basically 10% bleach? the authors used CLOROX which is ~6%), 90 mM Sodium Bicarbonate, 0.015% SDS and 0.0075% 2141-BG which is some weird proprietary fragrance which helps with solubility AND smells good? This is more in line with the classic RNase Away solutions. One important improvement to RNase-away-like mixes is sodium bicarbonate, which inhibits the corrosiveness of the bleach on lab equipment. Having watched bleach corrode the crap out of certain materials, the corrosion inhibition seems like a good call. The SDS and fragrance are wetting and emulsifying agents, respectively. The SDS needs the emulsifying agent to stay in solution. Both help the bleach/bicarbonate to make good contact with whatever mess you made (Fiillllthy, FILLLTTTHHHYYYYYYY!!!). The author notes that the bleach/bicarb solution itself is enough to destroy nucleic acids if you don’t have a high organic load.
So, why the two reagents together? Well, one reason is if you absolutely, positively HAVE to have 100% degradation of nucleic acid on the surface. If one of your reagents is diluted or absorbed by your mess, the second reagent acts as backup to ensure you have complete nucleic acid degradation. The dual action also seems to speed the effect of nucleic acid degradation, requiring no soak period. Wax on, wax off.
The inventors actually had labs compare the efficacy of 50% bleach (which is allegedly used in medical assays) VS Part A + Part B VS Only Part B. Turns out that while Part A + B are 100% effective in destroying nucleic acids, Part B by itself is still 99.3%. Now, how effective was 50% household bleach? 99.1%!!! They even did statistical tests to show that there is no difference in efficacy between the two part formulation and 50% bleach with a P value = 0.11.
So what can we take away from all this?
-50% bleach will destroy all nucleic acids on a surface within a minute
-bleach/bicarbonate pH 9.3 is equally effective, and is much less corrosive
– Adding SDS/emulsifier helps the already potent solution clean MORE BETTER by helping make better contact and removing organic load (Shmoo).
– Using a fragrance to hide the scent of bleach is a good idea, especially when that fragrance also keeps the SDS in solution
-If you must have all nucleic acids dead, DEAD, a solution of peroxide and copper will finish the job that your bleach didn’t.
– The authors don’t mention RNase activation, but looking at the previous patents this mixture would likely destroy most nucleases
So yeah, just throw some bleach on it, no worries.
Update: Here’s the decontamination solution recipe I’ve settled on. I use it on basically any surface I want to clean/decontaminate, watch out for your eyes though! It’ll burn them clear out of your eyeholes!
Decontamination Solution (v1.3)
10-15% Store bought bleach (100-150 mL/L)
1% NaOH (10 g/L)
1% Alconox/Sparkleen/dish soap (10 g/L) *
90 mM sodium bicarbonate (7.5 g/L) **
* Commercial versions use SDS, but at higher concentrations (=>1%) the SDS will tend to crash out. Unless you have the 2141-BG fragrance/emulsifier, either use a lower concentration of SDS (<0.1%) or use the above detergents *
** Sparkleen and Alconox have sodium bicarbonate already in it in high concentrations, up to ~40% for Alconox, so the addition of bicarbonate may not be necessary.
Assuming Sparkleen has 30% bicarbonate, 10 grams of sparkleen has 3 grams bicarbonate, which would make a final solution that has 36 mM bicarbonate, which could still provide corrosion inhibition, depends how strongly you want to believe the 90 mM from the DNAzap patent. **
*** This decon mix will corrode aluminum and iron/cheap stainless steel at high concentrations and when treating for long periods of time. Good quality stainless hold up fine. ***
**** This mix is awesome for cleaning glassware, let a beaker sit in 0.5X or 1X decon mix for a while, the longer the better. It will sparkle after you rinse it! The high NaOH content is reminiscent of base baths used by chemists to etch a nice clean layer on their glass. ****
本文来自：https://pipettejockey.com/2016/11/01/just-bleach-it/
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