Molecularly imprinted polymers embedded with double perovskite quantum dots: A ratiometric fluorescence sensor for visible and fluorescent determination of Rhein

A ratiometric fluorescence sensor based on molecularly imprinted polymers embedded with double perovskite quantum dots (green fluorescent CsPbBr3 (GPQDs) and red fluorescent CsPbI3 (RPQDs)) were prepared for the visible and fluorescent determination of Rhein. Double perovskite quantum dots were synthesized by a one-pot method with in-situ hydrolysis, and the fluorescent probes containing GPQDs and RPQDs with molecularly imprinted cavities (MIPs@RPQDs/GPQDs@SiO2) were synthesized by sol gel method. And the synthesized MIPs@RPQDs/GPQDs@SiO2 can emit two stable and independent fluorescence peaks at 520 nm with green fluorescence and at 695 nm with red fluorescence respectively. Since Rhein could specifically quench the red fluorescence without affecting the green fluorescence at 520 nm, a ratiomitric fluorescence sensor could be and was constructed with GPQDs as the internal standard signal and the RPQDs as the response signal. The sensor had a good linear relationship with the concentration of Rhein between 15 and 135 nM, and the detection limit was 1.90 nM (S/N = 3). Moreover, Rhein could be detected by observing the color transformation of the fluorescent probe directly with naked eyes. In addition, Rhein in the traditional Chinese medicine Rheum palmatum L. had been detected by the constructed ratiometric fluorescene probe with satisfactory.