Spectral-Kinetic Characteristics of the Photoluminescence of AIS/ZnS–PEI Semiconductor Quantum Dots in Aqueous Solutions and Their Application in Clinical Morphology

A study was carried out on the pH-dependence of the parameters of the time-resolved and steady-state photoluminescence of Ag–In–S₂ (AIS) quantum dots with surface-active polyethylenimine (PEI) groups in aqueous solutions. The high sensitivity of the PEI structure to pH in a broad range was shown to affect the mobility of the charge carriers in AIS QDs and, as a consequence, the mechanism of the dipole moment transition in the QDs. Using the Stark model and assuming no electrical field on the ZnS shell comprising the QD surface in environments with neutral pH and in ovarian tissues without pathology, shifts in the solution toward either acidic or basic values cause change in the electrical field in the local environment of the QDs manifested in change in the QD photoluminescence parameters (band maximum position and intensity, average lifetime). AIS-QDs under these conditions can act as a contrast agent in clinical morphology. Using confocal microspectrometry, we found AIS–PEI QDs to be useful not only for visualization but also for screening of ovarian malignancies.