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4LD-I-13
LASER DIAGNOSTICS AND SPECTROSCOPY
Laser spectroscopy of interactions at the carbon nanoparticle-medium interface
T. Dolenko1, S. Burikov1, A. Vervald1, K. Laptinskiy2
1- Department of Physics, Lomonosov Moscow State University, Leninskie Gory 1/2, 119991 Moscow, Russia 2- Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Leninsky Gory 1/2, 119991 Moscow, Russia tdolenko@mail.ru
The unique combination of properties of such carbon nanoparticles (CNPs) as carbon dots (CDs) and nanodiamonds (NDs) make them promising for applications in biomedicine and in technological processes. These nanoparticles have stable and intense luminescence and multifunctional surface, they are non-toxic and biocompatible. Therefore, CNPs can be used as luminescent markers and nanosensors, adsorbents and drug carriers. However, for effective applications it is necessary to understand the mechanisms of formation of CNPs surface luminescence, to know the influence of environment on colloidal, luminescent, adsorption properties of NDs and CDs in various solvents and biological tissues. In biomedicine, it is necessary to make sure that nanoparticles are safe for surrounding molecules. Therefore, the study of interactions at the carbon nanoparticle-medium interface is an actual problem [1].
The report presents the results of the research of the NDs and CDs interactions with the surrounding molecules in normal and heavy water, protonic and aprotonic solvents, solutions of salts and surfactants, proteins and DNA and of the effects of these interactions on the pointed CNPs properties. It was found that the intensity of CNPs photoluminescence increases primarily with an increase in the amount of sp2-/amorphously hybridized carbon on their surface, and secondarily with an increase in the number of surface oxygen-containing groups. The photoluminescence of oxidized CNPs depends on the value of the environment pH [2]. The mechanism of pH influence on the CNPs photoluminescence is due to (de)protonation of carboxyl and hydroxyl groups on their surface. This conclusion is confirmed by quantum calculations of diamond core structures with surface groups.
Using Raman laser spectroscopy, a general tendency has been established for all investigated CNPs to weaken hydrogen bonds in proton solvents. At the same time, the properties of the CNP themselves depend on the strength of the hydrogen bonds in the suspensions. The significant influence of CNPs on the strength of the hydrogen bonds, on the one hand, and the influence of the hydrogen bonds of environment on the CNPs properties, on the other hand, was found for the first time. The dependence between the efficiency of DNA, proteins and salt ions interactions with the NDs surface groups and the changes of NDs luminescence was found. A significant effect of NDs on the micelle formation of surfactants in water has been discovered and explained [3]. The dependence of this effect on the ratio of hydrophilic and hydrophobic groups on the CNPs surface and in the environment is established. NDs have no effect on the formed micelles, which proves the safety for biotissues.
As a result of the study of the interactions of CDs with metal ions, including heavy metal cations, the selectivity of the CDs luminescence sensitivity to certain ions was discovered and confirmed by calculations of molecular dynamics. The discovered effects provide prospects for the use of CDs as nanosensors of heavy metal cations.
The results were obtained using Raman laser spectroscopy, photoluminescent spectroscopy, Coherent Anti-Stokes Raman scattering, 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/project/22-12-00138/
[1] T. Dolenko, S. Burikov, K. Laptinskiy, J. Rosenholm, O. Shenderova, I. Vlasov, Evidence of carbon nanoparticle - solvent molecule interactions in Raman and fluorescence spectra, Physica Status Solidi A, vol.212(11), pp. 2512-2518, (2015).
[2] A. Vervald, A. Lachko, O. Kudryavtsev, O. Shenderova, S. Kuznetsov, I. Vlasov, T. Dolenko, The Effect of Environment pH on Surface Photoluminescence of Oxidized Nanodiamonds, J. Phys. Chem. C, vol.125(33), pp. 18247-18258, (2021).
[3] A. Vervald, S. Burikov, K. Laptinskiy, T. Laptinskaya, I. Vlasov, O. Shenderova, T. Dolenko, Nanodiamonds and surfactant in water: hydrophobic and hydrophilic interactions, J. of Colloid and Interface Science, vol.547, pp. 206-216, (2019).
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