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

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 CsPbBr PQDs (CsPbBr@SiO) was synthesized via a simple method. The SiO 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 CsPbBr@SiO 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 CsPbBr@SiO 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 CsPbBr@SiO was stable to water and oxygen, and sensitive to ambient pH, we applied CsPbBr@SiO to the detection of glucose. CsPbBr@SiO showed fantastic selectivity and sensitivity to glucose, and the detection limit can even reach 18.5 μM. Furthermore, CsPbBr@SiO was successfully applied to the detection of glucose in the human serum with satisfactory performance.