salt the metal ion loaded nanoparticles can then be dialyzed for 2 hours to remove unbound metal and lyophilized for storage the presently disclosed subject matter will now be described more fully hereinafter with reference to the accompanying examples in which representative embodiments are shown the presently disclosed subject matter can however be embodied in different forms and should not be construed as limited to the embodiments set forth herein rather these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the embodiments to those skilled in the art as set forth in the examples below various different metal ions have been loaded onto phosphate functionalized nanoparticles including cu co ni mn fe cr and others and two different metals fe and cu have been loaded onto the same nanoparticle loading metal solutions included cuso 4 ue8a0 5h 2 o cocl 2 ue8a0 6h 2 o niso 4 ue8a0 6h 2 o mnso 4 ue8a0 h 2 o feso 4 ue8a0 7h 2 o crcl 3 ue8a0 6h 2 o and feso 4 ue8a0 7h 2 o and cuso 4 ue8a0 5h 2 o together for the fe and cu loaded in combination of these six metals tested initially all were.