Near-infrared-emitting colloidal Ag2S quantum dots excited by an 808 nm diode laser

Zhang, Yanyan; Xia, Jinfeng; Li, Caixia; Zhou, Guohong; Yang, Wei; Wang, Dandan; Zheng, Huiping; Du, Yuansheng; Li, Xi; Li, Qiang

doi:10.1007/s10853-017-1131-5

Cited by 15 publications

(10 citation statements)

References 29 publications

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“…The prepared Ag 2 S NIR QDs can be used for in vitro fluorescence labeling and in vivo optical imaging agents by coating composed of branched polyethyleneimine (PEI)–25 kDa and l‐cysteine (Cys). Li used thioglycolic acid (TGA) as ligand prepared TGA coated Ag 2 S QDs. The as obtained Ag 2 S QDs demonstrates both excitation and emission in the NIR window.…”

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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“…For symmetric and asymmetric CH 2 stretching vibrations in the region of 2980-2850 cm −1 ), as well as for all types of CH 2 bending vibrations (1220-1230 cm −1 , 1125-1133 cm −1 , 910-750 cm −1 [13,15,[45][46][47][48][49]), variations within 5-15 cm −1 were detected. This feature is also a sign of the interaction between TGA and the Ag 2 S QD surface.…”

Section: Ftir Spectra Tga Molecules Passivating Ag 2 S Qdsmentioning

confidence: 90%

“…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: 93%

“…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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