Optical fiber fluorescence Cu sensing technology based on CdSe/ZnS quantum dots: Large detection range, low detection limit.

BACKGROUND

Copper ion (Cu), a crucial heavy metal ion, is closely associated with human health and the ecological environment. Imbalances in Cu can result in health issues for humans and damage to the ecosystem. Therefore, it is essential to detect Cu in the environment. However, current Cu sensors still face challenges such as limited detection range, poor detection limits, high costs, and complex preparation processes. Clearly, there is a need for a Cu sensor with an extensive detection range, low detection limit, cost-effectiveness, and simple preparation methods that enable online monitoring and real-time measurement of Cu.

RESULTS

In this paper, a high-performance optical fiber fluorescent Cu sensor based on polyethylene glycol diacrylate (PEGDA) hydrogel encapsulated CdSe/ZnS quantum dots (QDs) is designed and fabricated. Due to the porous nature of PEGDA hydrogels, large-diameter CdSe/ZnS QDs are confined within the hydrogels, while small molecules Cu are allowed to permeate them. Cu reacts with QDs, resulting in the fluorescence quenching of QDs, which enables the detection of Cu. Experimental results show that the sensor can quantitatively analyze Cu in the concentration range of 0.1-200 μM, with a limit of detection (LOD) of only 0.8 nM, and the fastest response time is only 5 s. Additionally, the sensor exhibits strong specificity, has been successfully applied to real water sample detection, demonstrates good stability, and shows great potential for real-time Cu detection.

SIGNIFICANCE

The sensor possesses a large detection range and low LOD, and the synthesis of its core fluorescent probe is straightforward and expedient. Specifically, the fluorescent probe can be synthesized by subjecting a solution of hydrogel precursors doped with CdSe/ZnS QDs to UV irradiation for approximately 2 min. This method is particularly suitable for monitoring confined environments and holds significant implications for the production of Cu sensors capable of real-time detection.