A Chemiluminescence Sensor for the Detection of α-Fetoprotein and Carcinoembryonic Antigen Based on Dual-Aptamer Functionalized Magnetic Silicon Composite

In this work, a dual-aptamer functionalized magnetic silicon composite was prepared and used to construct a chemiluminescence (CL) sensor for the detection of α-fetoprotein (AFP) and carcinoembryonic antigen (CEA). First, SiO₂@Fe₃O₄ was prepared, and polydiallyl dimethylammonium chloride (PDDA) and AuNPs were sequentially loaded on SiO₂@Fe₃O₄. Subsequently, the complementary strand of CEA aptamer (cDNA₂) and the aptamer of AFP (Apt₁) were attached to AuNPs/PDDA-SiO₂@Fe₃O₄. Then, the aptamer of CEA (Apt₂) and G quadruplex peroxide-mimicking enzyme (G-DNAzyme) were sequentially connected to cDNA₂, leading to the final composite. Then, the composite was used to construct a CL sensor. When AFP is present, it will combine with Apt₁ on the composite to hinder the catalytic ability of AuNPs to luminol-H₂O₂, achieving AFP detection. When CEA is present, it will recognize and bind with Apt₂, so G-DNAzyme is released to solution and catalyzes the reaction of luminol-H₂O₂ to achieve CEA determination. After the application of the prepared composite, AFP and CEA were detected in the magnetic medium and supernatant, respectively, after simple magnetic separation. Therefore, the detection of multiple liver cancer markers is realized through the CL technology without additional instruments or technology, which broadens the application range of CL technology. The sensor for detecting AFP and CEA shows wide linear ranges of 1.0 × 10^-4 to 1.0 ng·mL^-1 and 0.0001-0.5 ng·mL^-1 and low detection limits of 6.7 × 10^-5 ng·mL^-1 and 3.2 × 10^-5 ng·mL^-1, respectively. Finally, the sensor was successfully used to detect CEA and AFP in serum samples and provides great potential for detection of multiple liver cancer markers in early clinical diagnosis.