Nanoprobes consisting of QDs and single-domain antibodies (sdAbs) were implemented for the single- and double-photon detection and imaging of human micro-metastases, disseminated tumor cells in samples of metastatic BC mouse models, expressing HER2 or non-specific carcinoembryonic antigen (CEA), expressed by various cancer types. The gene discussed is CEACAM5; the disease is breast cancer.