Dual-mode sensing platform for Bisphenol A detection via bifunctional CsPbBr3@Cu-MOF assisted fluorescence and colorimetric analysis

Background

Bisphenol A (BPA) has been identified as an endocrine disruptor with numerous detrimental effects on human health. There is an urgent need to develop fluorescence/colorimetric dual-mode sensing approaches with expanded detection linear range, increased accuracy, and enhanced application flexibility for BPA detection. The utilization of fluorescence and colorimetric signals in point-of-care applications and real-time sensitive sensing further highlights the significance of developing novel and efficient fluorescence/colorimetric dual-mode sensing platform with high-efficiency probes.

Results

Herein, a fluorescence and colorimetric dual-mode aptasensor was developed by using CsPbBr₃@Cu-MOF as the aptamer immobilization matrix and signal generator. CsPbBr₃ was functionalized with Cu-MOF using a simple two-step strategy. This strategy involved in-situ formation and modified ligand-assisted precipitation technique with 4,4′-bipyridine (4,4-Bpy) serving as the bifunctional linker. The resulting CsPbBr₃@Cu-MOF exhibited improved stability in water and enhanced fluorescence. Additionally, it functioned as peroxidase mimetic to oxidize 3,3′,5,5′-tetramethyl benzidine (TMB), leading to a colorimetric change from colorless to blue. In the presence of BPA, aptamers were removed from CsPbBr₃@Cu-MOF. Consequently, the fluorescence and peroxidase-activity of CsPbBr₃@Cu-MOF were recovered, resulting in the enhanced fluorescence intensity and color change of TMB. Using this system, the proposed aptasensor demonstrated detection ranges of 1.0–80.0 nM with a LOD of 0.60 nM for the colorimetric method, and a linearity range of 0.1–100 nM with a LOD of 0.02 nM for the fluorescence method.

Significance

The obtained CsPbBr₃@Cu-MOF composites showed excellent fluorescence properties, good peroxidase-like activity, and aqueous stability. Furthermore, the proposed dual-mode aptasensor demonstrated simplicity, cost-effectiveness and good anti-interference abilities. This can be extended to the construction of other dual-mode sensors by changing aptamers and provides novel insights on the potential applications of perovskites in bioanalysis.