In a triplex sandwich assay by Wu et al., three QDs and micro-sized magnetic beads pairs were functionalized with monoclonal antibodies that targeted three lung cancer biomarkers in solution: cytokeratin 19 (CYRFA 21-1), carcinoembryonic antigen (CEA), and neuron-specific enolase (NSE) [23]. Here, CEACAM5 is linked to lung carcinoma.