Retracted Article: A facile cation exchange-based aqueous synthesis of highly stable and biocompatible Ag<sub>2</sub>S quantum dots emitting in the second near-infrared biological window

Gui, Rijun; Sun, Jie; Liu, Dexiu; Wang, Yanfeng; Jin, Hui

doi:10.1039/c4dt00699b

Cited by 48 publications

(22 citation statements)

References 54 publications

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“…Jin reported a simple synthesis of nontoxic Ag 2 S QDs on the basis of ion exchange between toxic visible luminescent CdS QDs and Ag + ions in the aqueous phase. The prepared Ag 2 S QDs (≈3.5 nm) showed representative NIR‐II emission, high fluorescence stability and a quantum yield up to 2.3%.…”

Section: Preparations Of Ag2smentioning

confidence: 99%

Recent Advances of Low Biological Toxicity Ag₂S QDs for Biomedical Application

Chen

et al. 2018

Adv Eng Mater

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In this review, the synthesis and biomedical application of Ag 2 S quantum dots(QDs) are comprehensively summarized with a particular focus on biological imaging and nanomedicine. For the first, the authors introduce the optical properties of Ag 2 S QDs, and then, the auhtors summarize a range of synthetic methods for Ag 2 S QDs. The subsequent section provides the applications of Ag 2 S QDs in optical imaging, photoacoustic imaging, sensing, optical tracking, and photothermal therapy. Finally, the authors provide insights into the overall situation, challenges, and future directions in this field.

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Section: Preparations Of Ag2smentioning

confidence: 99%

Recent Advances of Low Biological Toxicity Ag₂S QDs for Biomedical Application

Chen

et al. 2018

Adv Eng Mater

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“…Using the obtained data on FTIR spectra of various ionic forms, FTIR spectra of TGA molecules adsorbed on QDs surface were interpreted. For all FTIR spectra of the Ag 2 /TGA QD samples, we observe that the peak corresponding to the stretching vibrations of the S-H group of TGA (2559 cm −1 ) vanishes, which indicates the appearance of interactions between the thiol terminal group of TGA and dangling bonds at the 2 QD interfaces [13,15,[45][46][47][48][49].…”

Section: Ftir Spectra Tga Molecules Passivating Ag 2 S Qdsmentioning

confidence: 94%

“…With increasing the concentration of [S 2− ] ions from Na 2 S during formation of Ag 2 S/TGA QDs (Figure 2d), a slight high-frequency shift of 7-10 cm −1 was observed for the peak of asymmetric stretching vibrations ν as (COO − ) = 1567 cm −1 together with a low-frequency shift by 3-5 cm −1 for symmetric stretching vibrations ν s (COO − ) = 1388 cm −1 , probably caused by the interaction of thiol with the Ag 2 S QD surface. The intensity ratio for the peaks of asymmetric and symmetric stretching vibrations of the carboxylic group COO − in the two cases under consideration (Figure 2d) corresponds to the situation when the carboxylic end groups are not attached to the surface of the Ag 2 S QD interface [13,15,[45][46][47][48][49]. For the sample (Figure 2d) synthesized at the precursor ratio [AgNO 3 ]:[TGA]:[Na 2 S] starting from 1:0.9:0, a significant low-frequency shift of the peak of symmetric stretching vibrations ν s (COO − ) from 1388 cm −1 to 1359 cm −1 was observed together with a high-frequency shift of the peak of asymmetric stretching vibrations ν as (COO − ) from 1567 cm −1 to 1579 cm −1 .…”

Section: Ftir Spectra Tga Molecules Passivating Ag 2 S Qdsmentioning

confidence: 98%

“…Passivation of Ag 2 S QDs by TGA molecules gives rise to peaks of asymmetric and symmetric stretching vibrations of the carboxylic group (COO − ) (1584 cm −1 and 1387 cm −1 , respectively), which indicates adsorption of TGA molecules on the Ag 2 S interfaces in the ionic form with a free carboxylic terminal group COO − [13,15,[45][46][47][48][49]. With increasing the concentration of [S 2− ] ions from Na 2 S during formation of Ag 2 S/TGA QDs (Figure 2d), a slight high-frequency shift of 7-10 cm −1 was observed for the peak of asymmetric stretching vibrations ν as (COO − ) = 1567 cm −1 together with a low-frequency shift by 3-5 cm −1 for symmetric stretching vibrations ν s (COO − ) = 1388 cm −1 , probably caused by the interaction of thiol with the Ag 2 S QD surface.…”

Section: Ftir Spectra Tga Molecules Passivating Ag 2 S Qdsmentioning

confidence: 99%

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Thioglycolic Acid FTIR Spectra on Ag2S Quantum Dots Interfaces

et al. 2020

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The mechanism features of colloidal quantum dots (QDs) passivation with thioglycolic acid molecules (TGA) for cases of different luminescent properties is considered using FTIR. This problem is considered based on FTIR spectra analysis for various ionic forms of TGA. Experimental TGA molecules FTIR spectra is interpreted, basing on the data on modeling of TGA vibrational modes, realized in the framework of density functional method (DFT /B3LYP/6-31+G(d)) taking into account the vibrations anharmonicity of every functional group. This approach provides a significant improvement in the agreement between the experimental and calculated data. FTIR spectra of Ag 2 S/TGA QDs with exciton and recombination luminescence are differ from each other and B “freeB” TGA molecules. The ν ( S − H ) TGA peak (2559 cm − 1 ) disappears in FTIR spectra of Ag 2 S/TGA QD samples. This fact indicates the interactions between TGA thiol group and dangling bonds of Ag 2 S nanocrystals. Ag 2 S QDs passivation with TGA molecules leads to emergence ν a s (COO − ) (1584 cm − 1 ) and ν s (COO − ) (1387 cm − 1 ) peaks. It indicates TGA adsorption in ionic form. For Ag 2 S/TGA QDs with exciton luminescence we observed (a) significant low-frequency shift of ν s (COO − ) peak from 1388 cm − 1 to 1359 cm − 1 and high-frequency shift of ν a s (COO − ) peak from 1567 cm − 1 to 1581 cm − 1 ; (b) change in the ratio of intensities of ν a s (COO − ) and ν s (COO − ) vibrations. This feature is caused by the change in the symmetry of TGA molecules due to passivation of Ag 2 S quantum dots.For Ag 2 S/TGA QDs with recombination luminescence, the insignificant high-frequency shift of 7–10 cm − 1 for ν a s (COO − ) at 1567 cm − 1 and low-frequency shift of 3–5 cm − 1 for ν s (COO − ) at 1388 cm − 1 , probably caused by the interaction of thiol with Ag 2 S surface is observed. Using FTIR spectra, it was found that IR luminescence photodegradation is also accompanied by changes in the thioglycolic acid molecules, which capped Ag 2 S QDs. In the case of Ag 2 S QDs with exciton luminescence, the degradation process is non-reversible. It is accompanied by TGA photodegradation with the formation of α -thiol-substituted acyl radical (S-CH 2 -CO • ) TGA.

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“…At the same time, it also has high fluorescence stability and fluorescence quantum efficiency. Ag 2 S quantum dots have smaller particle sizes [3.7 nm (Zhao and Song, 2014), 1.6-6.8 nm , 2.6-3.7 nm (Gui et al, 2014b), 3.5 nm (Gui et al, 2014a)], which are very suitable for bioimaging applications.…”

Section: Semiconductor Quantum Dotsmentioning

confidence: 99%

Recent Progress in NIR-II Contrast Agent for Biological Imaging

Cao

Zhu

Zheng

et al. 2020

Front. Bioeng. Biotechnol.

223

190

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Fluorescence imaging technology has gradually become a new and promising tool for in vivo visualization detection. Because it can provide real-time sub-cellular resolution imaging results, it can be widely used in the field of biological detection and medical detection and treatment. However, due to the limited imaging depth (1-2 mm) and self-fluorescence background of tissue emitted in the visible region (400-700 nm), it fails to reveal biological complexity in deep tissues. The traditional near infrared wavelength (NIR-I, 650-950 nm) is considered as the first biological window, because it reduces the NIR absorption and scattering from blood and water in organisms. NIR fluorescence bioimaging's penetration is larger than that of visible light. In fact, NIR-I fluorescence bioimaging is still interfered by tissue autofluorescence (background noise), and the existence of photon scattering, which limits the depth of tissue penetration. Recent experimental and simulation results show that the signal-to-noise ratio (SNR) of bioimaging can be significantly improved at the second region near infrared (NIR-II, 1,000-1,700 nm), also known as the second biological window. NIR-II bioimaging is able to explore deep-tissues information in the range of centimeter, and to obtain micron-level resolution at the millimeter depth, which surpass the performance of NIR-I fluorescence imaging. The key of fluorescence bioimaging is to achieve highly selective imaging thanks to the functional/targeting contrast agent (probe). However, the progress of NIR-II probes is very limited. To date, there are a few reports about NIR-II fluorescence probes, such as carbon nanotubes, Ag 2 S quantum dots, and organic small molecular dyes. In this paper, we surveyed the development of NIR-II imaging contrast agents and their application in cancer imaging, medical detection, vascular bioimaging, and cancer diagnosis. In addition, the hotspots and challenges of NIR-II bioimaging are discussed. It is expected that our findings will lay a foundation for further theoretical research and practical application of NIR-II bioimaging, as well as the inspiration of new ideas in this field.Keywords: fluorescence imaging technology, the second region near infrared (NIR-II), biological imaging, contrast agents, biomedical applications Frontiers in Bioengineering and Biotechnology | www.frontiersin.org

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Retracted Article: A facile cation exchange-based aqueous synthesis of highly stable and biocompatible Ag₂S quantum dots emitting in the second near-infrared biological window

Cited by 48 publications

References 54 publications

Recent Advances of Low Biological Toxicity Ag₂S QDs for Biomedical Application

Recent Advances of Low Biological Toxicity Ag₂S QDs for Biomedical Application

Thioglycolic Acid FTIR Spectra on Ag2S Quantum Dots Interfaces

Recent Progress in NIR-II Contrast Agent for Biological Imaging

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Retracted Article: A facile cation exchange-based aqueous synthesis of highly stable and biocompatible Ag2S quantum dots emitting in the second near-infrared biological window

Cited by 48 publications

References 54 publications

Recent Advances of Low Biological Toxicity Ag2S QDs for Biomedical Application

Recent Advances of Low Biological Toxicity Ag2S QDs for Biomedical Application

Thioglycolic Acid FTIR Spectra on Ag2S Quantum Dots Interfaces

Recent Progress in NIR-II Contrast Agent for Biological Imaging

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Product

Resources

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Retracted Article: A facile cation exchange-based aqueous synthesis of highly stable and biocompatible Ag₂S quantum dots emitting in the second near-infrared biological window

Recent Advances of Low Biological Toxicity Ag₂S QDs for Biomedical Application

Recent Advances of Low Biological Toxicity Ag₂S QDs for Biomedical Application