In order to do that, typically organic solvents are pretty good, such as dehydrated DMSO or dehydrated DMF. You can run your reaction in these solvents until the coordination is complete between Au-SH.

Chandra K Dixit Hi，dear Dixit，Do you have ready protocols about bioconjugation of antibody to AuNP with HS-PEG-NHS？

Chandra K Dixit Dear Chandra，We found AuNP aggregating when I resuspened the AuNP pellet with DMSO，how can the reaction form Au-S bond between HS-PEG-NHS and AuNP in DMSO？ Thank you very much！