In other embodiments of the invention, {HEAD ~ the active agent} comprises {TAIL ~ a paramagnetic element} 
comprises
In other embodiments of the invention , { HEAD ~ the active agent } comprises { TAIL ~ a paramagnetic element }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL