In situ detection of the Zn2+ release process of ZnO NPs in tumour cells by confocal laser scanning fluorescence microscopy

The use of zinc oxide (ZnO) nanoparticles (NPs) for cancer is not yet clear for human clinical applications, which is primarily due to the lack of a better understanding of the action mechanisms and cellular consequences of the direct exposure of cells to these NPs. In this work, the authors have selected zinquin ethyl ester, a Zn²⁺ ‐specific fluorescent molecular probe, to efficiently differentiate ZnO NPs and Zn²⁺, and combined with confocal laser scanning microscopy (CLSM) to in situ study the Zn²⁺ release process of ZnO NPs in cancer cell system through detecting the change of Zn²⁺ level over time. During the experiments, the authors have designed the test group ZnO‐2 in addition to assess the influence of a long‐term storage on the characteristics of ZnO NPs in aqueous solution, and the Zn²⁺ release process of ZnO NPs in cancer cell system. After three‐month storage at room temperature, the release process became earlier and faster, which was consistent with previous results of transmission electron microscope, UV‐Vis and PL spectra. It is a good detection method that combination of Zn²⁺ ‐specific fluorescent molecular probe and CLSM, which will be helpful for ZnO NPs using in clinical research.Inspec keywords: cancer, cellular biophysics, fluorescence, laser applications in medicine, molecular biophysics, nanomedicine, nanoparticles, optical microscopy, positive ions, tumours, zinc, zinc compoundsOther keywords: zinc oxide nanoparticles, tumour cells, confocal laser scanning fluorescence microscopy, zinquin ethyl ester, zinc‐specific fluorescent molecular probe, cancer cell system, aqueous solution, room temperature, transmission electron microscope, ultraviolet‐visible spectra, photoluminescence spectra, time 3 month, temperature 293 K to 298 K, ZnO, Zn²⁺