A colorimetric aptasensing assay with adjustable color mutation points for threshold-readout detection of carcinoembryonic antigen

Direct readout of the clinically significant threshold for the disease judgment is convenient for point-of-care disease screening. Here, we designed a colorimetric aptasensing platform with adjustable color mutation points for threshold-readout detection of carcinoembryonic antigen (CEA) on the test strip. This platform involves a capture module made of a magnetic bead-supported sandwich aptamer, a signal transduction module based on a hybridization chain reaction (HCR) system with tunable mercury ion (Hg2+) binding capacity, and a colorimetric readout based on the Hg2+-regulated peroxidase-like activity of gold nanoparticles (AuNPs). Notably, the tunable Hg2+ binding capacity of the HCR allows the adjustment of the color mutation point over a range of CEA concentrations from 4 to 25 ng mL−1. This platform also exhibits a sensitive detection performance with detection limit of 0.19 ng mL−1 and a reliable clinical diagnostic capability with sensitivity of 100% and specificity of 96.667%. Since the targeting aptamer can be easily changed, this platform also offers the possibility for threshold-readout detection of other disease markers (e.g., prostate-specific antigen (cutoff value of 4 ng mL−1) and alpha-fetoprotein (15 ng mL−1)). Therefore, this platform provides a convenient and straightforward tool for point-of-care screening of disease markers.