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0Raman-fluorescence tags for bioimaging by plasmon-enhanced spectroscopy
E. Solovyeva*, V. Svinko, A. Smirnov, A. Demenshin, A. Shevchuk, A. Smirnov
Institute of Chemistry, Saint-Petersburg State University, Saint Petersburg, Russian Federation
* solovyeva.elena.v@gmail.com, e.solovieva@spbu.ru
The development of bioimaging tools for cells, tissues and organs is important to improve the quality and completeness of medical diagnosis and treatment. The potential of gold nanoparticles as optical amplifiers and photothermal agents has been demonstrated repeatedly in many studies [1,2]. Hybrid structures based on gold nanoparticles combined with chromophores not only consolidate the beneficial properties of the two components, but can also demonstrate synergistic effects, such as enhanced Raman scattering, luminescence and etc. However, the development of hybrid bioimaging tags requires thorough optimization of their composition and structure. In this work, we present a wide range of core-shell tags (Fig. 1), differing in the morphology of gold nanoparticle, shell material, chromophore used, its position and method of immobilization in the shell (electrostatic adsorption or covalent conjugation).
Plasmonic hybrids
Fig. 1. General representation of hybrids composition developed for bioimaging by plasmon-enhanced spectroscopy.
The optical studies of the tags were performed by surface-enhanced Raman scattering (SERS) and fluorescence spectroscopy for both colloidal suspensions and incubated cell samples. The optimized parameters were found at which the tags are able to operate in a bimodal regime. The refusal of covalent conjugation of the chromophore and its location at a distance of 2-3 nm from the plasmonic core are the key factors in achieving the bimodality.
Biological tests revealed that obtained hybrid structures undergo endocytosis, regardless of the morphology of gold core and coating material, and are localized in the cell cytoplasm. Cytotoxicity tests showed that the tags are non-toxic in the concentration range of 5-15 ^g/mL.
This work was funded by Russian Science Foundation, grant № 22-73-10052. The authors would like to thank the Resource Centers of SPbU: "Optical and Laser Materials Research", "Chemical Analysis and Materials Research", "Physical Methods of Surface Investigation", "Center for Molecular and Cell Technologies", "Computing Center" and "Cryogenic Center".
[1] A.N. Smirnov, A.I. Shevchuk, A.V. Volkova, V.D. Kalganov, E.V. Solovyeva, Gold-silica plasmonic nanobones with tunable size and optical bimodality for bioimaging, Colloids Surf. A, vol. 684, 133115, 2024.
[2] V.O. Svinko, A.N. Smirnov, A.I. Shevchuk, A.I. Demenshin, A.A. Smirnov, E.V. Solovyeva, Comparative study of fluorescence core-shell nanotags with different morphology of gold core, Colloids Surf. B, vol. 226, 113306, 2023.
