Upconversion Nanoprobes Applied In Effective Capture And Sensitive Detection Of Circulating Tumor Cells

Circulating tumor cells (CTCs) shed from the primary tumor into bloodstream isan important indication of cancer metastasis. Their effective capture and detection aretherefore of great importance in cancer diagnosis and prognosis. However, due to theextraordinarily rare number of CTCs in the blood of cancer patients (one in106hematologic cells), the development of new CTCs detection technology that is easyoperation and highly sensitive still merits further explorations.In this study, aptamer conjugated upconversion nanoparticles (UCNPs) are usedfor the first time as nanoprobes to recognize tumor cells, which are then enriched byattaching with magnetic nanoparticles (MNPs) and placing in the presence of amagnetic field. Firstly, a thiolated aptamer targeting PTK-7over-expressed on a varietyof cancer cells, together with biotin molecules, were co-conjugated to UCNPs used fortumor cell recognition. Then, we use MNPs conjugated with avidin to separate CTCs.Owing to the auto-fluorescence free nature of upconversion luminescence imaging, aswell as the magnetic separation to further reduce background signals, our techniqueallows for highly sensitive detection and collection of small numbers of tumor cellsspiked into healthy blood samples.As the results, highly sensitive detection of as few as10tumor cells spiked intowhole blood is realized. Moreover, the captured cells could be easily collected forfurther careful analysis. Taken together, our developed approach could be a promisingstrategy with high specificity and sensitivity for convenient and sensitive CTCsdetection and separation, showing great potential for future clinical diagnosis andprognosis of cancer.