ИСТИНА

The relevance of the development of optical nanosensors of environmental parameters is due to the active development of science and industry, where the problem of controlling the content of various substances in multicomponent media is becoming increasingly acute. At present, the development of such nanosensors is necessary for biomedicine, technological production, and ecology. Оne of the most promising bases for sensors are carbon dots (CD). According to the results of many publications, CD synthesized by certain methods have photoluminescence (PL) that is sensitive to environmental parameters, which makes it possible to develop sensors of these parameters based on CD. In our study, the objects of the study were CD synthesized using the hydrothermal method of synthesis from citric acid and ethylenediamine. The effect of temperature, pH of the environment, as well as ions Fe3+, Cr3+, Al3+, Co2+, Cu2+, Pb2+, Zn2+, Ni2+, Mg2+ present in the medium, on the PL of our CD was found. In this study, the mechanisms of the influence of pH and temperature on the CD PL were studied. It was shown that the influence of pH on the surface photoluminescence of nanoparticles with hydrogen-containing groups is due to the (de)protonation of surface carboxyl, hydroxyl, and amide groups. This conclusion is confirmed by quantum calculations of the behavior of surface groups at various pH and by the results of analysis of dependences of CD ζ-potentials on the pH. Using the artificial neural networks, CD-based nanosensors were developed that allow measuring the temperature and pH of the environment with an accuracy of 0.67°C and 0.005, respectively [1]. As a result of studying the interactions of CD with ions of the pointed metals, the sensitivity of CD PL to certain ions was discovered and confirmed by molecular dynamics calculations. It was found that all the studied metal ions quench the CD PL to some extent. Using the Stern-Volmer theory and measured PL decay kinetics, it was found that Cu2+, Zn2+, Ni2+, Mg2+ are characterized by static photoluminescent CD-nanosensor was developed to determine the concentration of four ions Cu2+, Cr3+, Ni2+, and NO3- in water simultaneously. The use of convolutional neural networks to solve the problem provided average absolute errors in determining the concentrations of Cu2+, Cr3+, Ni2+ и NO3- ions of 0.28 mM, 0.24 mM, 0.79 mM, and 1.15 mM, respectively [2]. The obtained errors in determining the concentrations of the investigated heavy metal cations fully satisfy the needs of monitoring the composition of waste and process waters [3]. The results were obtained using laser photoluminescence spectroscopy, laser time-resolved spectroscopy, laser correlation spectroscopy, IR absorption spectroscopy. The research was carried out at the expense of the grant of the Russian Science Foundation No. 22-12-00138, https://rscf.ru/en/project/22-12-00138/