SiO2-coated CsPbBr3 quantum dots for visual detection of small-molecule metabolite pyruvate

All-inorganic perovskite CsPbX3 quantum dots (QDs) have excellent optical properties and show promising applications in biomolecular detection. However, they are unstable in water and polar solvents. Although complete encapsulation methods can improve stability, they severely suppress the QDs' fast anion exchange (FAE) activity, which is crucial in biosensing applications. Here, double-sided SiO2-coated CsPbBr3 QDs (ds-CsPbBr3@SiO2) with high water stability and FAE activity were synthesized. The fluorescence lifetime extends to 46.44 ns, and the fluorescence intensity decays by only 21.8% after reacting with water for 60 min, which is far superior to that of uncoated samples. Small-molecule metabolite in serum, such as pyruvate (Pyr), is closely associated with various diseases. Based on ds-CsPbBr3@SiO2, a Pyr sensing platform using a fluorescence wavelength shift as the signal was constructed. The platform demonstrates a responsive range of 0–220 μmol/l of Pyr, which covers the physiological concentration range of Pyr in serum.