Color-Encoded Assays for the Simultaneous Quantification of Dual Cancer Biomarkers.

For the first time, the scattering light of noble nanoparticles was applied for the simultaneous detection of dual cancer biomarkers. Two nanoprobes with dual scattering light colors were used for the simultaneous imaging of alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) based on the sandwich-type immunoassay. Since AFP can combine anti-AFP-modified gold nanoparticles, which have green scattering light under the dark-field microscopic imaging (iDFM) technique, while CEA can conjugate anti-CEA-immobilized silver nanoparticles, which have blue scattering light, the simultaneous determination of AFP and CEA can be achieved by separately counting the number of green and blue light spots in iDFM. The mutual interference between the detection processes of AFP and CEA in the dual detection was investigated, and a negligible interference was found when the concentration of the antigen was in the range of 0.5-10 ng/mL, indicating the practicability of the simultaneous sensitive detection of dual targets. Furthermore, AFP and CEA in serum samples were also quantified directly without additional sample pretreatment, demonstrating the potential applications of the developed method in clinical diagnosis.