Cathodic Electrochemiluminesence Microscopy for Imaging of Single Carbon Nanotube and Nucleolin at Single Tumor Cell

Cathodic electrochemiluminesence (ECL) microscopy based on luminol analog L012 was originally established to implement the imaging of a single nanotube and nucleolin on a single tumor cell. This microscopy utilizes multiwalled carbon nanotubes (MWCNTs) as advanced coreactant accelerators to efficiently convert dissolved oxygen (O₂) and H₂O₂ into reactive oxygen species (ROS) due to excellent electrocatalytic properties. The produced ROS could oxide L012 into an excited state of L012 leading to a bright cathodic ECL illumination, thereby promoting ECL imaging of MWCNTs at a low triggering potential. After being modified with AS1411 aptamers, MWCNTs@AS1411 probes were incubated with tumor cells for specific ECL imaging of nucleolin on the plasma membrane, which permits cathodic ECL microscopy for label-free bioassays without ECL tags. The L012-based cathodic ECL microscopy with a moderate operating potential and label-free characteristics provides a universal approach in single nanomaterial and single-cell imaging and analyses.