Hi All,
I have SERS microspheres, they're silica coated and I've used APTES to functionalise the surface.
I'm aware that the amine can be converted to carboxyl via succinic anyhdride, this takes about 24hrs
I was wondering if I added gluteraldehyde, then glycine and some cyanoborohydride would this give me non zero-length carboxyl functionalised surface for EDC/NHS?
I ask for several reasons,
Firstly: I'm attempting to cut down on the length of time it takes to prepare the sensors for immunoassay,
Secondly: to to provide some distance from the surface and minimise steric effects
Thirdly: I don't want to use glutaraldehyde with the protein directly, as I don't want to include the borohydride with it.
Last: I've read that when using EDC/NHS it is prefereable for the surface be the carboxyl moiety
Thanks in advance for any that take the time.
Stjepan
//Which reaction conditions are you using with succinic anhydride?//
It was to stir for 24 hrs at 0.1M in DMF at RT
//There are ways to speed that reaction up.//
I would appreciate that info
//The glutaraldehyde approach isn't at all a bad idea - however it involves many more steps and therefore many more things could go wrong. Plus, if your reaction with succinic anhydride is slow - these alternatives will make it even slower.//
This was a concern, I just thought that as the reaction is relatively quick, it would at least cut down on time.
//1. Have you considered halo carboxy acids, starting from the amine? (I don't know how much "abuse" your microspheres can take)?//
I hadn't considered this, it would be much more direct, I think I may try it.
//2. Have you considered epoxy-funtionalized acids under slightly basic conditions?//
I had considered epoxy functionalising the surface with glycidyloxypropyl trimethoxysilane, instead of the APTES, however it's not to hand currently
//3. Have you considered a di-carboxy acid either protected on one end or deprotected and in excess with NHS/EDC coupling?//
I have considered it, however I currently don't have access to the reagents to use one that's protected, and I assumed that using a dicarboxylic acid would result in both ends reacting, is there a way to ensure directionality without protection? Would excess diacid serve this purpose?
Stjepan,
Thanks very much, I'll have a read of that paper, will probably try it out, maybe with a polypeptide.
I'm going to try out the DMAP catalyst also, have you any suggestion about concentration in that reaction.
Again, much appreciated
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