Ag₂S Quantum Dot: A Bright and Biocompatible Fluorescent Nanoprobe in the Second Near-Infrared Window

Abstract

Ag2S quantum dots (QDs) emitting in the second near-infrared region (NIR-II, 1.0~1.4 μm) are demonstrated as a promising fluorescent probe with both bright photoluminescence and high biocompatibility for the first time. Highly selective in vitro targeting and imaging of different cell lines are achieved using biocompatible NIR-II Ag2S QDs with different targeting ligands. The cytotoxicity study illustrates the Ag2S QDs with negligible effects in altering cell proliferation, triggering apoptosis and necrosis, generating reactive oxygen species (ROS), and causing DNA damage. Our results have opened up the possibilities of using these biocompatible Ag2S QDs for in vivo anatomical imaging and early-stage tumor diagnosis with deep tissue penetration, high sensitivity, as well as elevated spatial and temporal resolution owing to their high emission efficiency in the unique NIR-II imaging window.

Gold Nanostar Substrates for Metal-Enhanced Fluorescence through the First and Second Near-Infrared Windows

“…1 Ag 2 S QDs were selected as the NIR-II fluorophore to test because, among the limited number of probes reported to date, these benefit from high biocompatibility and tunability of their emission to discrete wavelengths. 38,75 However, their low fluorescence quantum yield (<10%), limits their exploitation in imaging applications.…”

LaF3 core/shell nanoparticles for subcutaneous heating and thermal sensing in the second biological-window

“…Recent studies dealing with the heating effects and the light-induced cytotoxicity during in vitro imaging experiments have pointed out 808 nm as an optimal excitation wavelength, since it simultaneously minimizes both the laser-induced thermal loading of the tissue and the intracellular photochemical damage. 23,[26][27][28] The existence of high power, cost-effective laser diodes operating at 808 nm also makes this specific wavelength interesting from a technical point of view.In this sense, the design and synthesis of a single NP capable of simultaneous heating and thermal sensing, and operating in the II-BW, appears to be especially captivating and, also, quite challenging. A potential way to join different structures or sub-structures in a single one is the use of the so called core/shell engineering.…”

“…Recent studies dealing with the heating effects and the light-induced cytotoxicity during in vitro imaging experiments have pointed out 808 nm as an optimal excitation wavelength, since it simultaneously minimizes both the laser-induced thermal loading of the tissue and the intracellular photochemical damage. 23,[26][27][28] The existence of high power, cost-effective laser diodes operating at 808 nm also makes this specific wavelength interesting from a technical point of view.…”

Facile synthesis of β-lactoglobulin capped Ag2S quantum dots for in vivo imaging in the second near-infrared biological window

“…Notably, the emission spectra of NIR-II emitting Ag2S QDs do not show clear sizedependent shift as reported in previous paper 45 . Moreover, the QY was calculated to be 5.68 % using the IR-26 dye as the reference standard (QY = 0.11%) 7,46 . Fig.…”

“…As a result, NIR-II fluorescence imaging can allow deep penetration into biological tissues with excellent imaging fidelity, sensitivity and resolution. [5][6][7] Over the past few years, considerable efforts have been devoted to develop high-quality NIR-II emitters including single-walled carbon nanotubes (SWNTs), [8][9][10] quantum dots (QDs), [11][12][13][14][15][16][17] rare-earth-doped nanoparticles (NPs), [18][19][20] and polymeric fluorophores. 21,22 Among them, the no toxic heavy metal-containing Ag2S QDs have become one of the most intensively studied NIR-II emitters.…”