Coupling of metal containing homing devices to liposomes via a maleimide linker: use of TCEP to stabilize thiol-groups without scavenging metals.

Liposomes for drug delivery are often prepared with maleimide groups on the distal end of PEG to enable coupling of homing devices, such as antibodies, or other proteins. EDTA is used to stabilize the thiol group in the homing device for attachment to the maleimide. However, when using a homing device that contains a metal, EDTA inactivates this by scavenging of the metal.