An azacrown ether-based near-infrared fluorescent probe for the detection of Pb2+ and its applications in food, environmental water, plant and animal samples

Background: Lead ion (Pb²⁺), as a kind of heavy metal ion, is particularly harmful to human health and ecosystems due to its high toxicity and easy bioaccumulation. Fluorescent probes capable of selective and sensitive detection of Pb²⁺ are crucial for enabling rapid and on-site monitoring and regulation, thereby mitigating its adverse health and environmental impacts. Additionally, the development of fluorescence probes for the detection of Pb²⁺ in plant systems is rarely reported. Accordingly, the development of near-infrared (NIR) emission fluorescence probe for the detection of Pb²⁺ in food, environment and in vivo is of great significance.

Results: In this work, an azacrown ether-based NIR fluorescence probe LCE1 was reported for the detection of Pb²⁺. Probe LCE1 can generate 1:1 complex with Pb²⁺, resulting in the inhibition of ICT effect to reduce the fluorescence signal. LCE1 exhibited many advantages, including NIR emission (λ_em = 670 nm), high selectivity and sensitivity (LOD = 0.34 μM) and fast response (30 s). The quantitative determination of Pb²⁺ in real food and water samples has been achieved with good recovery using LCE1 as the probe. Concurrently, the on-site and rapid determination of Pb²⁺ in water sample was realized by smartphone-assisted LCE1-based test strip technology. Notably, the fluorescence imaging of Pb²⁺ in cells and Animals has been successfully implemented using the probe LCE1. Most importantly, the fluorescence imaging of Pb²⁺ in Pb-hyperaccumulator plant samples has been successfully demonstrated.

Significance: LCE1 could provide new methods for understanding the physiopathological roles of Pb²⁺, evaluating food safety and selecting Plants used to remediate soil contaminated by heavy metals.

Bioimaging; Hyperaccumulator; Lead ion; Near-infrared probe; Real samples; Smartphone.