Molecularly imprinted polymer coating-assisted CsPbBr₃ perovskite quantum dots/TiO₂ inverse opal heterojunctions for the photoelectrochemical detection of cholesterol

Photoelectrochemical sensors have outstanding advantages including high sensitivity and miniaturization for outdoor use. Recently, perovskite quantum dots have attracted significant attention due to their high photoluminescence quantum yield. Nonetheless, there is still a strong need to improve their performance in challenging aqueous biological applications. In this paper, based on the molecularly imprinted polymer encapsulation of CsPbBr₃ perovskite quantum dot/TiO₂ inverse opal heterojunction structures, linear photoelectrochemical detection of cholesterol in aqueous solution was obtained without the involvement of an enzyme. The attenuation of photocurrent intensity under intermittent irradiation within 900 s (45 on/off cycles) was only 8.6%, demonstrating the superior stability of CsPbBr₃ based sensor here. At the same time, the minimum detection limit of 1.22 × 10⁻⁹ mol L⁻¹ in buffer conditions was lower than that reported for cholesterol photoelectric sensors. It has also been shown that the photoelectrochemical sensor of CsPbBr₃ here outperformed that of CH₃NH₃PbBr₃, which is another important member of the perovskite family. Finally, the proposed photoelectrochemical sensor platform was successfully applied in the determination of cholesterol in challenging serum with satisfactory recovery. The synergism among CsPbBr₃ perovskite quantum dots, TiO₂ inverse opal structure and imprinted polymer has led to greatly improved water stability, super selectivity and sensitivity, thus promoting the development of perovskite-based biological sensors. © The Royal Society of Chemistry 2023.