Synthesis and low-potential electrogenerated chemiluminescence of surface passivated phenol formaldehyde resin@CdS quantum dots

A novel method for the synthesis of polymer-stabilized quantum dots (QDs) was reported through a onepot hydrothermal reaction. Using this method, a phenol formaldehyde resin (PFR) polymer was formed in situ to passivate the surface of the CdS QDs with hexamethylenetetramine as the source of both the monomer and the crosslinking agent, HCHO. The PFR-capped QDs possessed a uniform size distribution with controllable surface states, and showed a unique electrogenerated chemiluminescent (ECL) spectrum with two peaks at 537 and 573 nm, which corresponded to the core and surface states of the QDs, respectively. The partially unpassivated surface state produced a low-potential ECL emission with a relatively long lifetime at 0.78 V. A new signal tag was thus designed for "signal-on" ECL immunoassay by concentrating QDs on carbon nanospheres to label the signal antibody, realizing the immunodetection of carcinoembryonic antigen. The excellent analytical performance indicated the promising application of the surface passivated PFR-capped QDs in optoelectronic and biomedical devices.