Detection of Myeloperoxidase and Osteopontin in Human Serum Using Single Particle-ICP-MS with MoS2 and ZnS Quantum Dots

MoS2 and ZnS quantum dots (QDs) were synthesized and applied as labels in magnetic immunoassays for the determination of myeloperoxidase (MPO) and osteopontin (OPN) via single-particle mode inductively coupled plasma mass spectrometry (ICP-MS). Primary MPO antibodies and primary OPN antibodies were captured by amino-modified magnetic nanoparticles, and the target biomarkers (MPO and OPN) were extracted and then specifically labeled with MoS2 QD-secondary MPO antibody and ZnS QD-secondary OPN antibody conjugates, respectively. MoS2 and ZnS QDs were employed as determination signal probes for ICP-MS measurements. Under the optimized conditions, the limits of detection obtained by magnetic immunoassay for MoS2 and ZnS QD-labeled MPO and OPN were 0.004 and 0.005 ng mL-1, respectively. The linear ranges for MPO and OPN were 0.01-50 and 0.02-50 ng mL-1, respectively. From six replicates, the relative standard deviations of MPO and OPN were found to be 3.5% and 3.2%, respectively. The proposed strategy was applied to determine the MPO and OPN levels in real human serum samples.