Development of oleic acid-functionalized magnetite nanoparticles as hydrophobic probes for concentrating peptides with MALDI-TOF-MS analysis.

The oleic acid-functionalized magnetite nanoparticles (OA-Fe(3) O(4) ) with mean diameter of about 15 nm were synthesized through a low-cost, one-pot method and were designed as hydrophobic probes to realize the convenient, efficient and fast concentration of low-concentration peptides followed by MALDI-TOF-MS analysis. The capability of OA-Fe(3) O(4) nanoparticles in concentration of low-abundance peptides from simple and complex solutions were evaluated by comparing them with a sort of C8-modified magnetic microspheres. Samples of standard peptide solution, protein digest solution and human serum were introduced in the evaluating process, and the OA-Fe(3) O(4) nanoparticles exhibited good surface affinity toward low-concentration peptides.