Fig. 4

The analysis of the specificity and affinity between the candidate aptamers and NGAL protein. a The specificity assay of the binding status between aptamers and bare magnetic beads, NGAL-coated beads, and normal human serum-coated beads using the qPCR method. b The Kd value of candidate aptamers was analysed after serial dilution, and NA53 aptamers possess the strongest binding capability on NGAL proteins. c NGAL protein and NA53 are colocalised in oesophageal squamous carcinoma cells KYSE450 using immunohistochemistry. Herein the green channel represents the interactions between aptamer library or NA53 and NGAL protein, the red channel represents the interactions between NGAL antibody and NGAL protein, and the blue channel represents the occurrence of nuclear after staining with DAPI, and the merged channel represents the overlap of green channel, red channel and blue channel