Conjugation of AM to streptavidin Dynabeads.

To be able to conjugate AM to magnetic Dynabeads, it was first activated by 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP) and then conjugated to biotin (61). Briefly, AM dissolved in H₂O at 1 mg/mL was added to CDAP (freshly prepared in Acetonitrile) to a final ratio of 1 mg of AM per 0.36 mg of CDAP, followed by biotinylation to a final ratio of 1 mg of AM per 0.57 mg of EZ-Link Amine-PEG3-Biotin (Thermo Fisher Scientific). After termination of the reaction by addition of 25 mM of glycine, the excess biotin was removed by dialysis against PBS, and the biotin-conjugated AM coupled to magnetic Dynabeads M-270 Streptavidin (Thermo Fisher Scientific) according to the manufacturer’s instructions.