Multifunctional AuAgPt Nanoframes for a Stimuli-Responsive Electrochemiluminescence Aptasensor

A multifunctional electrochemiluminescence (ECL) coreaction accelerator, AuAgPt nanoframes (NFs), is described for use in an ECL aptasensor for highly sensitive aflatoxin B1 (AFB1) detection. As a signal quencher, the broad UV-vis absorption spectrum of AuAgPt nanosheets (NSs) overlaps the ECL emission spectrum of g-C3N4@Au, triggering an ECL resonance energy transfer (ECL-RET). By the adjustment of the dosage of hydrogen peroxide (H2O2), the AuAgPt NSs are transformed into AuAgPt NFs because H2O2 etches Ag in AuAgPt NSs into Ag+, which disrupts the RET process. The as-formed AuAgPt NFs act as a coreaction accelerator to enhance the ECL response of the g-C3N4@Au/K2S2O8 system. Without AFB1, the Ag-dependent DNAzyme is inactive, and a strong ECL signal is observed. After AFB1 is added, the AFB1 aptamer targets AFB1 and the DNAzyme active site is exposed. As-generated Ag+ further activates DNAzyme to cut the substrate strand (S-DNA), which causes AuAgPt NFs to detach from the electrode surface and the ECL signal to significantly decrease. Under optimal conditions, the proposed ECL aptasensor exhibits high sensitivity with a limit of detection (LOD) of 0.11 fg/mL in the range of 1 fg/mL to 1 μg/mL for AFB1 detection.