I need to functionalize a glass surface with DNA (my method of functionalization is crosslinking amine terminated DNA to aminosilanized glass with gluteraldehyde). I then need to bond that functionalized slide to PDMS.
Im afraid O2 plasma will destroy my DNA probes. Any papers on this?
Im going to try the following but i was wondering if anyone has any input on how well any of these alternate methods work/methods to enhance these:
-Glass + PDMS + weight ==> oven 80C (would a hot plate work?)
-Piranha treat PDMS
-Plasma treat just PDMS
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3696384/ this is kind of intense, is there a way to do this without the UV?
Hi Nikhil
There is a method called multilayer soft lithography [1], where layers of PDMS with different ratios of the hardening agent are placed on top of each other and bonded without plasma activation.
I have used this method to bond PDMS and glass in my MSc. project: I made a PDMS membrane with 5:1 PDMS to hardening agent ratio, and then dyed the glass with a thin film of PDMS with 25:1 ratio, then I placed them on top of each other and baked them for 30 minutes in 85 degrees.
[1] M. A. Unger, H. P. Chou, T. Thorsen, A. Scherer, S. R. Quake, 2000, Monolithic microfabricated valves and pumps by multilayer soft lithography, Science 288, 113.
and the link to my MSc. thesis: (see pages 32-34)
https://www.researchgate.net/publication/317388673_Design_fabrication_and_modeling_of_an_electrostatically_actuated_microfluidic_valve
Thesis Design, fabrication and modeling of an electrostatically act...
Mask off the area that will be bonded to the PDMS with some PDMS while you do your APTES, gluteraldehyde and DNA treatments. Then mask the DNA coated area with PDMS when you do your plasma treatment. You can make a thin film "band-aid" of PDMS to selectively protect your coatings and glass as needed. Because the process of surface activation will cleave carbon bonds, any treatment that will activate the surface for bonding will damage DNA. With vacuum plasma, the surface treatment is line of sight from bulk plasma and only functional to a few molecular layers deep so it will be easy to mask. With UV/ozone or corona, there is not as much control of the depth of the reaction.
With the publication the authors plasma activates the PDMS to fabricate Si-OH groups which were exposed to 3-methacryloyl-propyltrimethoxysilane resulting in a surface which contains C=C groups. After that the DNA was used not before the plasma activation. The siloxane formation is an important step in this procedure.
Article Analysis of silanes and of siloxanes formation by Raman spectroscopy
Flexdym is a great alternative to PDMS, which does not require O2 plasma bonding.
The fabrication protocol is easy to use and only 2-15 minutes long, depending on your application. And because Flexdym is a thermoplastic, it can be recycled and re-molded. Check it out at https://eden-microfluidics.com/
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