Mathematical modeling of interactions of the carbon dots surface with metal ions using the method of molecular dynamics

Abstract

The relevance of the development of photoluminescent metal ion nanosensors is due to the active development of science and technology, where the issue of controlling the content of various substances in multicomponent media is becoming increasingly acute. One of the most promising bases for sensors is currently carbon dots (CDs), which have stable and intense photoluminescence (PL) that is sensitive to environmental parameters. So far, photoluminescent nanosensors of 1-2 metal ions in the medium have been developed on the basis of CDs. However, in practice, it is often necessary to control the presence and quantitative content of several ions at the same time. In order to determine the concentrations of several metal ions simultaneously by changing the PL spectra of nanoparticles, it is necessary to know how each of them affects the PL of the CD. This means that it is necessary to investigate the interactions of CDs with ions in the environment of nanoparticles and the mechanisms of influence of these interactions on the PL characteristics of the CD. It is reasonable to conduct such studies both experimentally and theoretically.
In this study, mathematical modeling of the interactions of CDs with different surface compositions - with carboxyl, hydroxyl and amide groups - with metal nitrate ions
Al3+, Cr3+, Fe3+, Ni2+, Pb2+ and Zn2+ using method of molecular dynamics was carried out, the experimental data on the effect of metal cations on nanoparticles photoluminescence were obtained and a comparative analysis of theoretical and experimental results was carried out. The study of the dynamics of interactions between metal ions and the CD surface was performed using the molecular dynamics method implemented in the LAMMPS package. The analysis of constructed radial distribution functions (RDF) of salt ions relative to the surface groups of CDs showed that there are 1, 2 or 3 hydrate layers between the surface carboxyl groups of nanoparticles and metal cations. Moreover, the fraction of the time spent by an ion through one layer correlates with the degree of extinguishing of PL of the CD by the same ion. The obtained results indicate the possibility of using the molecular dynamics method in the development of optical nanosensors of metal cations based on carbon dots.
The study was carried out at the expense of a grant from the Russian Science Foundation № 22-12-00138, https://rscf.ru/project/22-12-00138/.

Speaker

Kirill Kozhushnyy
Moscow State University
Russia

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