Cesium Lead Bromide (CsPbBr₃) Perovskite Quantum Dot-Based Photosensor for Chemiluminescence Immunoassays

Chemiluminescence immunoassays have been widely employed for diagnosing various diseases. However, because of the extremely low intensity chemiluminescence signals, highly sensitive transducers, such as photomultiplier tubes and image sensors with cooling devices, are required to overcome this drawback. In this study, a hypersensitive photosensor was developed based on cesium lead bromide (CsPbBr₃) perovskite quantum dots (QDs) with sufficient high sensitivity for chemiluminescence immunoassays. First, CsPbBr₃ QDs with a highly uniform size, that is, 5 nm, were synthesized under thermodynamic control to achieve a high size confinement effect. For the fabrication of the photosensor, MoS₂ nanoflakes were used as an electron transfer layer and heat-treated at an optimum temperature. Additionally, a parylene-C film was used as a passivation layer to improve the physical stability and sensitivity of the photosensor. In particular, the trap states on the CsPbBr₃ QDs were reduced by the passivation layer, and the sensitivity was increased. Finally, a photosensor based on CsPbBr₃ QDs was employed in chemiluminescence immunoassays for the detection of human hepatitis B surface antigen, human immunodeficiency virus antibody, and alpha-fetoprotein (AFP, a cancer biomarker). When compared with the conventionally used equipment, the photosensor was determined to be feasible for application in chemiluminescence immunoassays.