[DIYbio] Re: PLA biodegradation cocktail for 3D printing?

Here you have. I just found the last one, and it may give you some more reliable info about biodegradation, which seems some more feasible than I said before

El lunes, 12 de agosto de 2013 17:16:50 UTC+10, jarlemag escribió:

Thanks for the information! Seems like it might be tricky or not feasible to achieve biodegradation at a reasonable timeframe. Would you mind sharing some of your references?

Best regards,
JP

kl. 03:34:57 UTC+2 mandag 12. august 2013 skrev Xabier Vázquez Campos følgende:

PLA is usually considered degradable rather than biodegradable as the biodegradation only happens under very specific conditions. Indeed it can be degraded enzymatically and proteinase K seems to be one of the best options though it needs optimisation of the conditions. Also, the degree of crystallinity affects a lot to the potential enzymatic degradation, being very diminished when this parameter is higher than about 25%.
It also depends on the solvent used. I found some articles using enzymes in organic solvents being the best toluene at 50° C.

Regarding biodegradation s. str., it only happens (at least at good rates) under anaerobic conditions as those found in industrial composting taking up to 90 days, however, it doesn't occur in home-made composters. Degradation produces high ammounts of methane.

El sábado, 10 de agosto de 2013 06:08:37 UTC+10, jarlemag escribió:

Interesting idea. I've created a Mendeley group with a number of possibly relevant articles. Feel free to contribute: http://www.mendeley.com/groups/3571741/pla-biodegradation/

-JP

kl. 12:13:55 UTC+2 torsdag 8. august 2013 skrev Patrik D'haeseleer følgende:

So I was soaking the print nozzle of our 3D printer in acetone to get it unclogged. Problem is, we've printed both ABS and PLA plastic with it, and I know PLA doesn't dissolve in acetone. In fact, there's very little in terms of relatively safe solvents that will dissolve PLA. Which is rather ironic, since PLA is supposed to be biodegradable and stuff.

So here's a very interesting suggestion I stumbled upon while googling for a solution, by "Kevin R" on the Ultimaker forum:

https://groups.google.com/d/msg/ultimaker/8s1bq_9LsRM/VXz40PTjJq8J
"I've actually been looking into using PLA and PCL for a product I'm going to launch in the new year, so I've been learning about the biochemistry for their decomposition because... well... I'm a nerd. The problem with PLA is that really isn't as biodegradable as one might think, but it can be none the less (which is a far cry that what ABS can claim). To make a truly safe and environmentally friendly method of removing PLA supports, you would want to use a combination of a hydrolase (either/or a lipase and protease... protease seems to be best) and a polymerase to break down the polymer. These are the enzymes that fungi and bacteria use to catalyze the decomposition of the PLA into to its base units. At best PLA isn't overly biodegradable, so using the fungi alone would take a while. You could isolate and separate the hydrolase and polymerase, disperse them in water at relatively concentrated levels and use them as a bath (in theory they should last forever if you don't denature them). The best fungi for this (and seemingly the only fungi that can completely breakdown PLA) seems to be Tritirachium album but aside from a couple of us, who around here could get their hands on that? Here's a fun fact though: the second best fungi for PLA decomposition is Penicillin roqueforti which is your friendly neighborhood bread mold! This is the same fuzzy stuff that grows on your bread if you leave it too long and is what makes blue cheese blue. If there is a biologist in our midst with some free time, they might be able to get a culture to pump out the polymerase and protease into a solution that we could dip our parts into (heated up to the right activation temperature of course). If you feed the culture gelatin you might be able to spur the secretion of the polymerase."

That sounds entirely feasible, and an enzyme cocktail to dissolve PLA plastic might even be commercializeable, given the exponential growth in 3D printing these days. Would make for a wonderful synergy between two of the hottest nerd topics of the century - DIY 3D printing and DIYbio!

Patrik