Carbon Nanofibers Coated with Fe3O4 Nanoparticles and MnO2 Nanosheets further Modified with Molecularly Imprinted Polydopamine for Fluorescence Sensing of Carcinoembryonic Antigen

Nanoparticles are effective tools for signal amplification in chemical sensor construction. Herein, we present molecularly imprinted polymer (MIP)-based sandwich-structured fluorescence sensors for ultrasensitive detection of trace carcinoembryonic antigen (CEA) based on MnO2 nanosheet and MoS2 nanoflower dual signal amplification. MIPs were used as synthetic antibodies and prepared by a surface imprinting method using MnO2 nanosheet-loaded magnetic carbon fibers (CF/Fe3O4/MnO2) as solid supports by the self-polymerization of dopamine. The obtained CF/Fe3O4/MnO2/MIPs can specifically absorb the target CEA from complex samples, which can then be specifically labeled with boronic acid-modified MoS2-curcumin nanotags (BA-MoS2-CUR). Under alkaline conditions, CUR was detached from MoS2 and used as a fluorescence reporter molecule. Due to the high binding capacity of the MnO2 nanosheets and the high loading capacity of the MoS2 nanoflowers, the detection sensitivity of the molecularly imprinted fluorescence sensors was remarkably improved. Specific detection of CEA in the linear range of 0.01 ng/mL–10 μg/mL with a low LOD of 3.5 pg/mL (S/N = 3) was achieved. In addition, based on the MIPs and boronic affinity dual specific recognition ability, the detection selectivity was also improved. Finally, the concentration of CEA in human serum was determined by this approach.