Antigen retrieval assisted electrochemiluminescence imaging of surface antigens at single tissue section

Previously, our group has established an electrochemiluminescence (ECL) molecular imaging method to detect carcinoembryonic antigen (CEA) at single tissue sections of carcinoma patients. However, the tissue fixation blocks the binding sites of surface antigens affecting the antigen-antibody interaction and the resultant visualization sensitivity. Herein, we report an antigen retrieval assisted ECL imaging strategy that utilizes heat-induced epitope retrieval (HIER) to re-expose the binding sites of the antigens for more efficient interaction between surface antigen and ruthenium-labeled antibody. With more ruthenium complexes tagged with surface antigens, the ECL intensity at the tissue sections increases significantly which could more accurately reflect the amount and the distribution of surface CEA. Accordingly, the different distribution of CEA at the carcinoma and paracancerous regions of tissue sections from two patients with lung adenocarcinoma (LUAD) is visualized, which could not be easily distinguished without the HIER treatment. Eventually, the combination of antigen retrieval and ECL molecular imaging could improve the visualization sensitivity at single tissue section and minimize the false negative phenomenon, which will greatly advance the development of ECL-based tissue imaging for future application in pathological diagnosis.