Hi All,
I have been struggling to successfully conjugate PLGA copolymer to PEG using EDC-NHS. I have followed a protocol using chloroform as a solvent, a 5:1 ratio of EDC/NHS to PLGA for the activation step, and a 1:1 ratio of PEG to PLGA for the reaction.
I know EDC reactions are sensitive to water so I purged my reaction vial with N2.
If anyone could give me their insight into what may be going wrong here, it would be much appreciated.
Thank you!
EF
Are you filtering out the precipitate at regular intervals.
This reaction has a very poor progress rate but the product can be obtained, even though with less yield, to some extent.I guess you shd not be using a ratio of 2:1 to 2.5:1 of EDC-NHS:PLGA.
And maybe you can try an insitu reaction of activation and coupling steps.
If i got it right, you are basically trying to couple a (poly)carboxylic acid (PLGA) to an alcohol (PEG). Since alcohols are poor nucleophiles, including towards activated esters (like NHS carboxylates), a carbodiimide (such as EDC) + a catalytic amount of DMAP (0.05-0.1 eq) might the best alternative.
Sir, I suggest to use Oxyma, DMAP(catalytic amount) or Oxyma: EDC(1:1.1) NMP as base can use.
Use DCC, DMAP (1:0.1 molar ratio) reaction instead of EDC-NHS. You will get very good results. Caution: no water should be there not even trace amount
Maruthinath Karicheti :
Sir u have suggested oxyma or DMAP with EDC in 1:1 ratio, NMP as base , but i guess DMAP also is a base , can u elaborate on this. also plz do mention the suitable solvent for this reaction
Manoj Kumar:
Sir for DCC/DMAP coupling can u share the reference if u have it.
- Badges
- Science topic
- Similar topics
- Chemistry
- Sulfites
- Inorganic Chemistry