Visual and electrochemical determination of breast cancer marker CA15-3 based on etching of Au@Ag core/shell nanoparticles

In this work, a method for the visual and electrochemical detection of the breast cancer marker CA15–3 was developed based on the etching reaction of gold/silver core-shell nanoparticles (Au@Ag NPs) by mercury ions (Hg2+). Two kinds of nanocomplex of silicon dioxide nanospheres-antibodies-mercury ions (SiO2 NSs-Ab-Hg2+) and Au@Ag NPs-antibodies (Au@Ag NPs-Ab) were first prepared in the visual detection. In the presence of antigen, a sandwich structure of immuno-complex was formed through the specific recognition reaction of antigen and antibody. Then, after the addition of pH 4.6 CPBS, redox reaction occurred between Hg2+ and silver shell. With the increase of the amount of antigen, the silver shell was etched thinner and thinner, and the color changed obviously. Visual detection of CA15–3 could be realized in the range of 30–300 U/mL. In addition, we adopted the DPV signals generated by Hg2+ etching of silver shell to realize the electrochemical detection of CA15–3. The detection concentration range was 0.1–200 U/mL with a detection limit of 0.05 U/mL.