Silver ions enhanced AuNCs fluorescence as a turn-off nanoprobe for ultrasensitive detection of iodide

Abstract Fluorescence nanoprobes are frequently employed to construct sensitive biosensors via turn-on and turn-off strategy. In this paper, a novel strategy for ultrasensitive detection of iodide was firstly constructed based on Ag + regulated photoluminescence enhancement of gold nanoclusters (AuNCs) as a turn-off nanoplatform. In the presence of Ag + , the fluorescence (FL) intensity of AuNCs can be enhanced obviously. When adding iodide ions (I - ) in the Ag + -AuNCs, Ag + can be pulled down from AuNCs and results in quenching of the fluorescent effectively owing to the combination between Ag + and I - . Compared with that of I - directly reaction with AuNCs, the introducing of Ag + shows improved quenching efficiency from 32% to 66% since I - can react with Ag + as well as AuNCs. Therefore, the platform could be applied to assay Ag + and I - , on the basis of the FL enhancement and the further FL quenching. The detection ranges and detection limits were 0.2–12 μM and 0.06 μM for Ag + , 0.001–6 μM and 0.3 nM for I - , respectively. The new sensing method based on ion regulation to enhance the detection sensitivity can extend to the appliance of other fluorescent materials in biosensing and biomedical field.