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ZnO nanoparticles (NPs) were prepared and characterized by different analytical methods and then they were used to decorate with N, N´-bis(salicylidene)ethylenediamine (salen) in order to perform as receptor for the metal ions in an aqueous medium. The results show that ZnO-salen selectively detects Al 3+ ions in aqueous medium since the intensity of fluorescence has been enhanced significantly. However, the presence of K + in the medium further intensified the fluorescence emission for the [ZnO-salen-Al 3+ ] system. The above system has been applied to recognize Al 3+ and K + in cells by developing the cell images, for which, the fluorescence image is brightened if a human glioblastoma U251 cell contains [ZnO-salen-Al 3+ ] + K + ions, consisting of the fluorescence titration. The binding global constant for Al 3+ and the subsequent recognition of K + by ZnO-salen resulted in β 2 (Al 3+ ) = 6.61 × 10 3 and β 2 (K + ) = 3.71 × 10 3 with a detection limit of 36.51 µM for Al 3+ and 17.39 µM for K + . In the cell toxicity analysis, the cell viability was over 85% for the ZnO-salen even in the concentration as high as 100 mM., (© 2024. The Author(s).)

The present work highlights the sustainable approach for the transformation of plastic waste into fluorescent carbon dots (CDs) through carbonization and then they were functionalized with L-cysteine and o-phenylenediamine. CDs which were characterized by different analytical techniques such as X-ray diffraction (XRD), thermogravimetric analysis (TGA), Scanning electron microscopy (SEM), and transmission electron microscopy (TEM) are employed to recognize Cu 2+ , Fe 2+ , and Hg 2+ ions. The results show that the fluorescence emission was considerably quenched, and it is consistent with the interference and Jobs plots. The detection limit was found to be 0.35µM for Cu(II), 1.38 µM for Hg(II), and 0.51µM Fe(III). The interaction of CDs with metal ions enhances the fluorescence intensity detecting histamine successfully. It shows that plastic waste-based CDs can be applied clinically to detect toxic metals and biomolecules. Moreover, the system was employed to develop the cellular images using Saccharomyces cerevisiae cells with the support of a confocal microscope. Furthermore, theoretical studies were performed for the naphthalene layer (AR) as a model for C-dots, then optimized its structure and analyzed by using the molecular orbital. The obtained TD-DFT spectra coincided with experimental spectra for CDs/M 2+ /histamine systems., (© 2023. The Author(s).)