Screening of Aptamer for Breast Cancer Biomarker Calreticulin and Its Application to Detection of Serum and Recognition of Breast Cancer Cell

Calreticulin (CRT) is closely related to cancer, and it is considered to be a novel biomarker for invasion and metastasis of breast cancer, as well as an indicator of staging and prognosis. Here, we screened and identified aptamers of CRT for the first time with capillary electrophoresis-systematic evolution of ligands by exponential enrichment (CE-SELEX) technology. The Apt 23 with high affinity and specificity was screened and verified by CE, isothermal titration calorimetry and gold nanoparticles-based colorimetric assay. By using FAM-labeled Apt 23 (FAM-Apt23) as an affinity probe, CRT was detected in the concentration range of 1–1000 nmol/L in serum by laser-induced fluorescence detector with a detection limit of 0.5 nmol/L. FAM-Apt 23 could also be used as an immunofluorescence imaging probe, which could be bound to the surface of breast cancer cells 4T1 with overexpressed CRT. Preliminary studies showed that Apt 23 could be used as aptamer probe for CRT recognition and detection.