Highly Luminescent CuInS₂/ZnS Core/Shell Nanocrystals: Cadmium-Free Quantum Dots for In Vivo Imaging

Abstract

Strongly luminescent CuInS 2 /ZnS core/shell nanocrystals were synthesized from copper iodide, indium acetate, zinc stearate, and dodecanethiol as starting compounds in octadecene solvent. The as-prepared core/shell nanocrystals exhibit a low size distribution (<10%), and present photoluminescence in the range of 550-815 nm with a maximum fluorescence quantum yield (QY) of 60%. Time-resolved fluorescence spectroscopy revealed that the lifetimes of the different spectral components are on the order of hundreds of nanoseconds, indicating that donor-acceptor pair recombinations are at the origin of the observed emission bands. The CuInS 2 /ZnS nanocrystals were subsequently transferred to the aqueous phase via surface ligand exchange with dihydrolipoic acid and used as fluorescent labels for in vivo imaging. After tail vein injection into nude mice, the biodistribution of the quantum dots was monitored during 24 h using fluorescence reflectance imaging.

Synthesis of copper quantum dots by chemical reduction method and tailoring of its band gap

“…Due to this quantum confinement, quantum dots exhibits different opto-electronic properties, including their high emission quantum yield, size tunable emission profile and narrow spectral bands. [17][18][19][20] In this work, metallic copper nano particles were synthesized by chemical reduction method using a reducing agent sodium borohydride and coated with the surfactants citric acid and CTAB. Copper chloride solution was used as the initial precursor.…”

The performance of gradient alloy quantum dots in cell labeling

“…One possibility lies in the generation of Cd2+-free QDots, but thus far, the synthesis of these QDots remains to be further optimized and a lot of effort is being put into increasing their optophysical properties to be in the same line as the Cd2+-containing ones [24,25]. The coating of the QDots can also be modified, where double polymer-silica coatings have been shown to enhance the resilience of the QDots against environmental degradation of the QDots [26].…”

Real-Space Mapping of Surface Trap States in CIGSe Nanocrystals Using 4D Electron Microscopy

“…16,[23][24][25][26] Various surface passivation techniques, e.g., treatment with different ligands or shelling with higher bandgap materials, have been tried to reduce the detrimental effects of surface-related traps. 24,[27][28][29][30][31][32][33][34][35] However, in order to design more efficient passivation strategies for photoactive materials for any applications, precise knowledge about the surface charge carrier dynamics is a prerequisite.…”