Form 2 / Clear V2 resin: Non-specific DNA capture? Biocompatibility?

Hi folks!

I’m using the From2 / Clear V2 resin to print microfluidic prototypes to isolate DNA from bacterial samples. DNA yield was poor on the 3D printed device compared to standard manufacturer protocol. After thoroughly troubleshooting, it looks like there is some non-specific loss of DNA to the interior walls and channels.

Formlabs support suggested that the resin is highly inert and should not exhibit any affinity towards DNA.

Has anybody ever faced an issue similar to mine?

Any help is appreciated! Thanks!

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I have some limited experience with using Formlabs resins in microfluidic devices for nucleic acid analysis. I’m a mechanical engineer so I only learned a little bit from the biologists I worked with. We tested Clear V2 and Dental SG V1 to make sure they didn’t inhibit amplification reactions, and they performed acceptably in DNA and RNA amplification, but maybe that doesn’t say much about nonspecific binding. Could you use a blocking agent like a BSA solution to treat the surfaces of your device? I believe we treated membranes with BSA to prevent DNA from getting stuck on them.

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@piGuy thank you for the response! Using BSA solution is a good suggestion! What membrane did you treat with BSA? Did you treat clear V2 with BSA? I wonder if BSA treatment works the same with cured resin - something I will have to test.
That’s an interesting point you make about acceptable DNA and RNA amplification. If all of the temperature cycling conditions were maintained correctly, it’s possible that some of the amplified DNA stuck to the walls.

I’m a medical device engineer. While I am not a biology guy, I would probably steer you toward the resins that Formlabs has biocompatibility data for.

If it were me, I would be experimenting with Dental SG or Dental LT Clear for a few reasons. One - they are tested for biocompatibility. Two - because of that, they are unlikely to get significantly reformulated. If you use Clear resin and the formulation changes - you might end up having to revalidate everything you have done.

Just my $0.02

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@themedulla thank you for suggesting the dental SG and LT. You’re right about probable revalidation requirement with the clear resin if the formulation changes. The dental resins are “biocompatible” making them non-toxic when in the human body. While it’s possible that this property may help with non-specific DNA capture, it’s hard to say without testing. Appreciate your input! I will try them.

I never tried BSA blocking any parts made from Formlabs resin so I’m not sure if it would work, or what the proper protocol would be. Biocompatible resin like Dental SG is certainly going to be the best starting point, but whether you use Clear, Dental SG, or something else, I think it’s critical to thoroughly post cure the parts in UV light. My (admittedly limited) understanding of photopolymer resins in biological applications is that complete cross linking is absolutely necessary to reduce the reactivity of the material.

@piGuy You bring up a very important point there about post-processing the prints correctly. Thanks!

Hello!

I thought I would drop by and add my thoughts. :smiley: We are a dental lab and I don’t know if its worth mentioning but the dental SG is only biocompatible for 24 hrs. If you’re looking for something more long-term I would recommend the dental LT. However our company has not tried the SG or LT resins, we only use the dental model resin, but you most definitely need to wash them thoroughly and post-process like @piGuy mentioned. We wish you the best of luck!

Edit: Here’s the Formlabs’ PDF about dental LT, I believe you can skip to page 10 to learn how to properly clean and post-cure parts.

Perhaps the printing process left microstructure ridges or layers on the interior surfaces of your channels, increasing the surface area available to bind free DNA. Perhaps try flowing your DNA through with a dye like sybr green, waiting a bit, then inspecting the structure under floresence.

If ridges are part of the problem, you could attempt to smooth them out by forcing uncured resin through the microchannel and curing it with a brief blast of UV, then flushing with alchol. Another option (not sure how cross-reactive cyanoacrylates are w/ DNAs tho) is to make a 50/50 mixture of acetone + super glue. Flush a bolus of that through followed by air to lay down a smooth interior layer of superglue.