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Herein, an electrochemiluminescence (ECL) aptasensor for carcinoembryonic antigen (CEA) detection was developed based on Au-Ag/g-C3N4 nanocomposites (NCs), which were synthesized by decorating graphitic carbon nitride (g-C3N4) nanosheets with alloy-structured Au-Ag bimetallic nanoparticles (NPs) via one-step in situ chemical reduction. As ECL sensing platform, Au-Ag/g-C3N4 NCs could significantly improve the ECL intensity of luminol due to the good conductivity of Au-Ag NPs, electrocatalytic activity for oxygen evolution reaction (OER) and the ability to adsorb luminol via π stacking interaction. In addition, it could load the thiol terminated aptamers of CEA via Au-S or Ag-S bonds. In the presence of CEA, the ECL response of the proposed biosensor decreased significantly due to the fact that the assembled protein layers hindered the electron transfer and the diffusion of ECL reactants toward the electrode surface. The proposed ECL sensor exhibited a good linear relationship with CEA in the range of 1.0–1.0 × 10−6 ng/mL with a detection limit of 8.9 × 10−7 ng/mL. The satisfactory results were obtained in the detection of CEA in human serum samples.

Background: Water-dispersed lanthanide coordination polymers (LCPs) have attracted considerable attention owing to their superiority in bioanalysis. However, so far, most of the reported LCPs, due to the employment of water-insoluble and toxic organic molecules as ligands, are only competent in organic solution or the gaseous phase. Therefore, the construction of a water-dispersed, LCP-based, especially LCP nanoparticle (LCPNP)-based, sensor is still lacking and challenging., Objective: The aim was to obtain a novel and effective LCPNP-based sensor for Zn2+ by simple self-assembly, utilizing water-soluble guanosine monophosphate (GMP) as ligand and Eu3+ as luminescence center, ., Methods: In aqueous solutions, Eu-GMP NPs were formed via self-assembly reaction between Eu3+ and GMP, and displayed very weak fluorescence due to low energy transfer from GMP to Eu3+ and the rate constant of nonradiactive deactivation of the excited states caused by the O-H vibration of coordinated water molecules. After the introduce of Zn2+, forming Eu-GMP/Zn, very interestingly, an 8-fold fluorescence enhancement was observed due to the removal of coordination water molecules and fluorescence sensitization of Zn2+., Results: The fluorescence intensity of Eu-GMP NPs at 614 nm showed a linear relationship with the concentration of Zn2+ from 4 to 240 μM with a detection limit of 4 μM. Due to possessing long fluorescence, Eu-GMP showed prominent achievment for application in serum Zn2+ determination., Conclusion: The LCPNP probe exhibited excellent performance for the determination of Zn2+ in serum., Highlights: For the first time, we developed and designed a kind of water-dispersed, LCPNP-based turn-on fluorescence assay for Zn2+ in serum. High sensitivity and good recoveries were achieved due to long fluorescence life, good water-dispersed behavior, and the turn-on fluorescence response of the LCPNP probe., (© The Author(s) 2022. Published by Oxford University Press on behalf of AOAC INTERNATIONAL. All rights reserved. For permissions, please email: journals.permissions@oup.com.)