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Exfoliation and optical properties of near-infrared fluorescent silicate nanosheets

Published on ChemRxiv
: Selvaggio, Gabriele; Weitzel, Milan; Oleksiievets, Nazar; Oswald, Tabea A.; Nißler, Robert; Mey, Ingo; Karius, Volker; Enderlein, Jörg; Tsukanov, Roman; Kruss, Sebastian

Volltext ()

2021, 24 S.
Deutsche Forschungsgemeinschaft DFG
390677874; RESOLV
EXC 2033: Ruhr Explores Solvation
Deutsche Forschungsgemeinschaft DFG
Near infrared fluorescent nanomaterials: From photophysics and functional interfaces to biosensors
Deutsche Forschungsgemeinschaft DFG
SFB 803; 55908123
Functionality Controlled by Organisation in and between Membranes: Quantifying diffusion and dynamics of lipids within membranes in a leaflet-dependent manner (A10)
Preprint, Elektronische Publikation
Fraunhofer IMS ()
nanosheet; silicates; Exfoliation; near-infrared (NIR) fluorescence; microscopy; fluorescence lifetime; biophotonic

The silicates Egyptian Blue (CaCuSi4O10, EB), Han Blue (BaCuSi4O10, HB) and Han Purple (BaCuSi2O6, HP) emit in bulk bright and stable fluorescence in the near-infrared (NIR), which is of high interest for (bio)photonics due to minimal scattering, absorption and phototoxicity in this spectral range. So far the optical properties of nanosheets (NS) of these silicates are poorly understood. Here, we exfoliate them into nanosheets and report their physicochemical properties. The approach uses ball milling followed by tip sonication and centrifugation steps to exfoliate the silicates into NS with a lateral size ≈16-27nm and thickness ≈1-4nm. They emit at ≈ 927 nm (EB-NS), 953nm (HB-NS) and 924nm (HP-NS) and single NS can be resolved in the NIR. Fluorescence lifetimes decrease from ≈ 30-100μs (bulk) to 17μs (EB-NS), 8μs (HB-NS) and 7μs(HP-NS). NS of different composition/size can be imaged by fluorescence lifetime imaging, which enables lifetime-encoded multicolor imaging both on the microscopic and the macroscopic scale. Finally, remote imaging through tissue phantoms reveals the potential for bioimaging. In summary, we report a procedure to gain NIR fluorescent silicate nanosheets, characterize their photophysical properties and show their potential for NIR photonics.