Capture and Identification of Heterogeneous Circulating Tumor Cells Using Transparent Nanomaterials and Quantum Dots-Based Multiplexed Imaging

Background: Capture and identification of circulating tumor cells (CTCs) in the blood system can help guide therapy and predict the prognosis of cancer patients. However, simultaneous capture and identification of CTCs with both epithelial and mesenchymal phenotypes remains a formidable technical challenge for cancer research. This study aimed at developing a system to efficiently capture and identify these CTCs with heterogeneous phenotypes using transparent nanomaterials and quantum dots (QDs)-based multiplexed imaging. Methods: Hydroxyapatite-chitosan (HA-CTS) nanofilm-coated substrates were modified based on our previous work to increase the capture efficiency of cancer cell lines by extending baking and incubating time. QDs-based imaging was applied to detect cytokeratin, epithelial cell adhesion molecule (EpCAM), and vimentin of cancer cells to demonstrate the feasibility of multiplexed imaging. And QDs-based multiplexed imaging of CD45, cytokeratin and vimentin was applied to detect CTCs from different cancer patients that were captured using HA-CTS nanofilm substrates. Results: Comparisons of the capture efficiencies of cancer cells at different baking time of film formation and incubating time of cell capture revealed the optimal baking and incubating time. Optimal time was chosen to develop a modified CTCs capture system that could capture EpCAM-positive cancer cells at an efficiency > 80%, and EpCAM-negative cancer cells at an efficiency > 50%. QDs-based imaging exhibited comparable detection ability but higher photostability compared to organic dyes imaging in staining cells. In addition, QDs-based multiplexed imaging also showed the molecular profiles of cancer cell lines with different phenotypes well. The integrated CTCs capture and identification system successfully captured and imaged CTCs with different sub-phenotypes in blood samples from cancer patients. Conclusion: This study demonstrated a reliable capture and detection system for heterogeneous CTCs that combined enrichment equipment based on HA-CTS nanofilm substrates with QDs-based multiplexed imaging.