Ion imprinted dual reference ratiometric fluorescence probe for respective and simultaneous detection of Fe3+ and Cu2+

Abstract

In this work, an ion imprinted ratiometric fluorescence probe for simultaneous detection of Fe³⁺ and Cu²⁺ was first proposed using a dual template and dual reference strategy. As a proof of concept, blue emitter amino modified carbon dots (CDs) and red emitter carboxyl modified CdTe quantum dots (QDs) were adopted for their fluorescence signal output. The interference of other ions can be eliminated after the imprinting process. During detection of Fe³⁺, CDs were quenched with QDs as the reference. During detection of Cu²⁺, QDs were the response signal while CDs were the reference. Under optimal conditions, (I₄₂₀)₀/(I₆₂₀) displayed a good linear relationship with the concentration of Cu²⁺ in the range of 0.5–50 μM with a detection limit of 130 nM, while (I₆₂₀)₀/(I₄₂₀) displayed a good linear relationship with the concentration of Fe³⁺ in the range of 1.0–100 μM with a detection limit of 340 nM. Using this dual-template–dual-reference strategy, Fe³⁺ and Cu²⁺ can be detected simultaneously in real water samples with satisfactory recoveries. This work brings innovation to the signal output mode in the field of imprinted sensors, and provides a technological advancement to high-throughput detection.