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-CN@Au, triggering an ECL resonance energy transfer (ECL-RET). By the adjustment of the dosage of hydrogen peroxide (HO), the AuAgPt NSs are transformed into AuAgPt NFs because HO 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-CN@Au/KSO 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.