Magnetic chelating nanoprobes for enrichment and selective recovery of metalloproteases from human saliva

New magnetic nanoprobes based on surface-functionalized magnetite particles were synthesized and used to selectively capture metalloproteases from human saliva samples. In addition to their high specific surface area, these nanoparticles have metal ion chelating moieties grafted on their surface by the reaction with the organosilane EDTA-TMS ((N-(trimethoxysilylpropyl)-ethylenediaminetriacetate trisodium salt). The most distinct feature of these particles is their capability to selectively recover metalloproteases even in highly diluted saliva samples. The high affinity of these materials for metalloproteases was attributed to the formation of chelates between the chelating moieties and the metal ions of metalloproteases. These magnetic particles exhibited high colloidal stability in the biological standard buffers MES, HEPES, TEAB and Tris-HCl, within a significant pH range (pH 5-9) and, due to their magnetic features, enabled a fast separation of the metalloproteases from the medium by simply applying an external magnetic field. Thus, these materials were proven to be valuable probes for the selective enrichment and rapid recovery of metalloproteases from human saliva, particularly when dealing with trace amounts of material.