Optical immunosensor panel using quantum dot-antibody conjugates for highly sensitive detection of carbohydrate antigen 19–9 (CA19-9)
Daniela Oliveira, Pedro Oliveira, Aiqiang Xu, Eduarda Rodrigues, Susana G. Guerreiro, Rafael C. Castro, David S.M. Ribeiro, João L.M. Santos, Ana M. Piloto
Abstract
This study introduces a fluorescent immunosensor colour panel with antibody-conjugated quantum dots for detecting CA19-9 in human serum. The immunosensors presented decreasing fluorescence with increasing CA19-9 concentrations, with a linear detection range from 0.01 to 501.87 U mL -1 and detection limits of 1.66 × 10⁻⁴, 2.71 × 10⁻⁴, and 5.45 × 10⁻⁴ U mL -1 for the green-, orange-, and red-emitting conjugates in human serum. These limits are well below the 37 U mL -1 cutoff for early pancreatic cancer risk. The immunosensor panel is simple, sensitive, and specific, offering a visual colour readout for rapid CA19-9 detection, making it ideal for point-of-care applications. The results highlight the potential of the developed conjugates as a sensitive fluorescence colour panel for detecting CA19-9 across a wide range in human serum, both below and above the pancreatic cancer cutoff. With just 200 μL of sample and a single pre-filtration step, the assay delivers results in under 15 minutes, offering a cost-effective and efficient platform for point-of-care use. • Revised as per Data Administrator's request • Quantum dot conjugates serve as optical sensors for CA19-9 antigen detection. • A visual panel enables semi-quantitative tracking of CA19-9 levels in serum samples. • This approach shows potential for detecting various cancer biomarkers in real samples.