Glucose and pH responsive fluorescence detection system based on simple synthesis of silicon-coated perovskite...

Perovskite quantum dots (PQDs) are extremely unstable in ambient air due to their inherent structural instability, which limits the wide application of PQDs. In this work, silicon-coated CsPbBr₃ PQDs (CsPbBr₃@SiO₂) was synthesized via a simple method. The SiO₂ coating effectively isolated PQDs from water and oxygen in the environment, which were the main elements that destroyed the structure stability of PQDs. The synthesized CsPbBr₃@SiO₂ can be stored in water for more than 2 months and posessed wonderful dispersibility in aqueous solution. The fluorescence intensity remained unchanged within 7 days and only decreased by 11.9 % within 2 months. We found that CsPbBr₃@SiO₂ was extremely sensitive to environmental pH, and the fluorescence intensity decreased with the reduction of pH. In addition, an excellent linear relationship with pH value in the range of 1.0 ∼ 5.0 was achieved. As we all known that glucose can be catalyzed by glucose oxidase to produce gluconic acid and hydrogen peroxide, in which a good deal of protons were produced and the pH was gradually lowered. Since CsPbBr₃@SiO₂ was stable to water and oxygen, and sensitive to ambient pH, we applied CsPbBr₃@SiO₂ to the detection of glucose. CsPbBr₃@SiO₂ showed fantastic selectivity and sensitivity to glucose, and the detection limit can even reach 18.5 μM. Furthermore, CsPbBr₃@SiO₂ was successfully applied to the detection of glucose in the human serum with satisfactory performance.