I tried to attach p-SCN-Bn-DOTA on amine modified MSNs and the protocol says that I have to mix them in water/DMSO or water/water, or DMSO/DMSO and adjust the pH using NaOH (0.1 N) to 8, 8.5 or 9.
I tried this, however each time I changed the pH of particles to basic, I have noticed that they are degraded and couldn't be centrifuged and collected, although all papers use the same protocol mentioned above, and this is the only way I can conjugate this DOTA to NH2-MSN nanopartilces keeping carboxylates free for radiolabeling//chelation of radiometals
Does anyone have any suggestion to attach DOTA to my particles ?