Deciphering breast cancer cell heterogeneity: a quantum dot-conjugate approach employing MCF-7 and THP-1 co-cultures†

This study developed and utilized quantum dot conjugates labeled with antibodies (QD^λ/Ab) to analyze the heterogeneity of cancer cell populations in co-cultured MCF-7/THP-1 cells mimicking peripheral blood conditions. We synthesized QD^λ with emissions at 450 nm, 525 nm, and 615 nm, confirmed by transmission electron microscopy and X-ray diffraction analysis, suggesting distinct crystal structures and phase transitions. Surface modification with β-mercaptopropionic acid (QD^λ/MPAb), polyethylene glycol (QD^λ/MPA/PEG) and streptavidin (QD^{λ/MPA/PEG/SA}) enhanced biocompatibility and enabled specific antibody binding, as evidenced by consistent fluorescence and dynamic light scattering analysis. Flow cytometry and confocal microscopy validated the selective binding of antibodies to cancer markers and revealed significant heterogeneity within the cell populations. This study underscores the potential of QD^λ/Ab conjugates for precise cancer biomarker detection and heterogeneity assessment.