We do not have a system for oxygen plasma, corona discharge or ozone in our lab. We wanted to create reactive surface for our immunoassay on PDMS, such that it can bind to APTES. We have been using H2O2/HCL method, but the density is too low.
What would be some alternate methods which can be used on closed PDMS microchannels to achieve good results with high density?
You can use 6M NaOH to activate the surface. The difference is that plasma/corona/UV ozone are breaking the the Si-C bonds to leave Si-OH at the surface and NaOH will just replace the hydrogens with hydroxyls on the methyl side groups. This works quite well for APTES though.
Thanks for the answer. Do we need to maintain any special temperature for this? I used to maintain a temp of 55 Celsius for 1M NaOH, while working with PMMA for a similar protocol.
I've seen NaOH surface modification protocols running up to 75C but I personally run at room temperature to avoid bubble generation problems in fluidic channels. Some of those protocols use lower concentrations of NaOH as well and I have used concentrations as low as 1M but find that the 6M gives me the best results in a reasonable amount of treatment time (
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