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Aptamers selected from cell-SELEX have demonstrated their unique advantages as chemical antibodies in biosensing and bioimaging.We are making efforts to explore the use of aptamers for clinical analysis.We have selected a panel of aptamers targeting to EGFR-overexpressing A549 cells,a typical non-small cell lung cancer(NSCLC)cell line cells.The potential application of aptamer in the analysis of circulating tumor cells(CTCs)was investigated.CTCs are rare cancer cells detached from solid tumors and circulated in peripheral blood,which are regarded as "liquid biopsy" for treatment monitoring and tumor molecular analysis.We designed a CTC detection platform based on the modification of aptamers on the nanosubstrates in a microfluidic device.High capture yields and high release yields were obtained by spiking the A549 cells in blood samples,and molecular analysis of the point mutation was achieved for the released A549 cells.To enhance the capability of using aptamer for the capture of heterogeneous cancer cells from NSCLC cancer patients,we further developed a method of using aptamer cocktail as capture agents.The synergistic effects among individual aptamers lead to good capture performance for clinic samples.The results also suggest its potential use for tumor heterogeneity analysis.On the other hand,after the enrichment and identification of proteins that bind to the selected NSCLC aptamers,we verified that one aptamer-binding protein is a new and specific biomarker of NSCLC.Its expression is associated with patients clinic pathological feature of stage,lymph node metastasis and survival time in more than 500 clinical samples.Then we revealed the new biological functions of the protein in NSCLC development and inhibition mechanism of the aptamer as a therapeutic drug.Our work demonstrated a systematic and powerful approach to discover tumor biomarker and diagnostic/therapeutic target.