Synthesis from aqueous solutions and optical properties of Ag–In–S quantum dots

Lopushanska, B. V.; Azhniuk, Yu. M.; Lopushansky, V. V.; Molnar, S.B.; Studenyak, I.P.; Selyshchev, Oleksandr; Zahn, Dietrich R. T.

doi:10.1007/s13204-020-01407-w

Cited by 11 publications

(42 citation statements)

References 57 publications

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“…1a shows the optical absorption spectra of size fractioned colloidal AgInS2 QD solutions. Similar to earlier studies of Ag-In-S QDs [10,13,19], a noticeable blue shift of the absorption edge is observed with increasing fraction number as evidence for the NC size decrease. While for extensively studied II-VI QDs, for which (if the average QD size is smaller than the exciton Bohr radius) one can observe distinct size-dependent maxima in the optical absorption spectra and determine, from their spectral positions, the average QD size using the effective mass approximation [22], here we did not observe any confinement-related maxima.…”

Section: Resultssupporting

confidence: 88%

“…While for extensively studied II-VI QDs, for which (if the average QD size is smaller than the exciton Bohr radius) one can observe distinct size-dependent maxima in the optical absorption spectra and determine, from their spectral positions, the average QD size using the effective mass approximation [22], here we did not observe any confinement-related maxima. This fact is well known for Ag-In-S QDs and can be explained by smearing the maxima due to the strong Urbach tail absorption by defect states [10,13,19].…”

Section: Resultsmentioning

confidence: 67%

“…The essential role of the electron-phonon interaction for the PL mechanism in Ag-In-S QDs implies the importance of studying their phonon spectra which are most efficiently probed by Raman spectroscopy. Raman spectra of non-stoichiometric Ag-In-S QDs were reported recently [10,19,20], including a detailed targeted study [21]. Several studies were devoted to the phonon spectra of stoichiometric AgInS2 QDs [4,6,9], in most cases a quite limited number of spectra were presented, and analysis was encumbered by low signal-to-noise ratios and strong PL backgrounds.…”

Section: Introductionmentioning

confidence: 99%

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Optical Characterization of Colloidal AgInS2 Quantum Dots Synthesized from Aqueous Solutions

Lopushanska¹,

Azhniuk²,

Studenyak³

et al. 2022

J. Nano- Electron. Phys.

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Colloidal AgInS2 quantum dots (QDs) with intense broadband photoluminescence (PL) were synthesized in aqueous solutions in the presence of glutathione at mild conditions. Size-selective fractioning of QDs was performed by repeated centrifugation of the colloidal solution with the addition of 2-propanol. Based on the optical absorption and PL data, the dependences of the band gap and the PL maximum position on the QD size are analyzed. The Raman spectra of AgInS2 QDs exhibit only a slight variation with decreasing QD size explained by phonon confinement. Changes in the Raman spectra with increasing laser power density are most likely related to photoinduced oxidation of the AgInS2 QD surface with the formation of S-O bonds.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

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Optical Characterization of Colloidal AgInS2 Quantum Dots Synthesized from Aqueous Solutions

Lopushanska¹,

Azhniuk²,

Studenyak³

et al. 2022

J. Nano- Electron. Phys.

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“… 25 The other example to the pure PEI (10 kDa)-coated AIS QDs had a small hydrodynamic size and 32% QY but used a pressure cooker (120 °C) and did not report any long-term colloidal or luminescence stability. 22 Both had maximum emission below 600 nm. These examples clearly indicate the advantage of using a mixed coating and its utility in tuning size emission and imparting strong emission in an RT reaction.…”

Section: Resultsmentioning

confidence: 98%

“…These E g and Urbach energies agree with the values reported in the literature for the different anionic AIS QDs. 22 , 64 …”

Section: Resultsmentioning

confidence: 99%

One-Step Aqueous Synthesis of Anionic and Cationic AgInS₂ Quantum Dots and Their Utility in Improving the Efficacy of ALA-Based Photodynamic Therapy

et al. 2022

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Silver–indium–sulfide quantum dots (AIS QDs) have potential applications in many areas, including biomedicine. Their lack of regulated heavy metals, unlike many commercialized QDs, stands out as an advantage, but the necessity for alloyed or core–shell structures and related costly and sophisticated processes for the production of stable and high quantum yield aqueous AIS QDs are the current challenges. The present study demonstrates the one-step aqueous synthesis of simple AgInS 2 QD compositions utilizing for the first time either a polyethyleneimine/2-mercaptopropionic acid (AIS-PEI/2MPA) mixture or only 2-mercaptopropionic acid (AIS-2MPA) as the stabilizing molecules, providing a AgInS 2 portfolio consisting of cationic and anionic AIS QDs, respectively, and tuneable emission. Small AIS QDs with long-term stability and high quantum yields (19–23%) were achieved at a molar ratio of Ag/In/S 1/10/10 in water without any dopant or a semiconductor shell. The theranostic potential of these cationic and anionic AIS QDs was also evaluated in vitro. Non-toxic doses were determined, and fluorescence imaging potential was demonstrated. More importantly, these QDs were electrostatically loaded with zwitterionic 5-aminolevulinic acid (ALA) as a prodrug to enhance the tumor availability of ALA and to improve ALA-induced porphyrin photodynamic therapy (PDT). This is the first study investigating the influence of nanoparticle charge on ALA binding, release, and therapeutic efficacy. Surface charge was found to be more critical in cellular internalization and dark toxicity rather than drug loading and release. Both QDs provided enhanced ALA release at acidic pH but protected the prodrug at physiological pH, which is critical for tumor delivery of ALA, which suffers from low bioavailability. The PDT efficacy of the ALA-loaded AIS QDs was tested in 2D monolayers and 3D constructs of HT29 and SW480 human colon adenocarcinoma cancer cell lines. The incorporation of ALA delivery by the AIS QDs, which on their own do not cause phototoxicity, elicited significant cell death due to enhanced light-induced ROS generation and apoptotic/necrotic cell death, reducing the IC50 for ALA dramatically to about 0.1 and 0.01 mM in anionic and cationic AIS QDs, respectively. Combined with simple synthetic methods, the strong intracellular photoluminescence of AIS QDs, good biocompatibility of especially the anionic AIS QDs, and the ability to act as drug carriers for effective PDT signify that the AIS QDs, in particular AIS-2MPA, are highly promising theranostic QDs.

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Synthesis and Optical Properties of Ag–Ga–S Quantum Dots

Azhniuk

Lopushanska

Selyshchev

et al. 2022

Physica Status Solidi (b)

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Ag–Ga–S quantum dots (QDs) are obtained by colloidal synthesis in aqueous solutions with glutathione ligands at mild conditions. The QDs can be assigned to metastable orthorhombic, rhombohedral, or rocksalt‐type phases, assuming a significant internal pressure within crystallites, while the conventional tetragonal AgGaS2 phase is less likely formed. Similarly to these metastable phases, the QDs reveal a relatively narrow indirect bandgap contrary to the wide and direct bandgap of tetragonal AgGaS2. Size‐selected fractions of the colloidal solutions are separated by repeated centrifuging with addition of 2‐propanol. The QD size is evaluated from atomic force microscopy, while the crystallite size determined using the Scherrer formula is underestimated. X‐ray photoemission spectroscopy reveals that the QD composition changes from nearly stoichiometric for the fraction with the largest QDs toward Ag deficient and S rich for smaller QDs. The synthesized QDs are characterized by the absorption edge blueshift with decreasing QD size. A blueshift of the photoluminescence (PL) peak with decreasing QD size is observed as well as a nonmonotonous size dependence of the PL intensity. Raman spectra of the Ag–Ga–S QDs are discussed compared to those of bulk crystals and a strong contribution of surface phonons is revealed.

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Synthesis from aqueous solutions and optical properties of Ag–In–S quantum dots

Cited by 11 publications

References 57 publications

Optical Characterization of Colloidal AgInS2 Quantum Dots Synthesized from Aqueous Solutions

Optical Characterization of Colloidal AgInS2 Quantum Dots Synthesized from Aqueous Solutions

One-Step Aqueous Synthesis of Anionic and Cationic AgInS₂ Quantum Dots and Their Utility in Improving the Efficacy of ALA-Based Photodynamic Therapy

Synthesis and Optical Properties of Ag–Ga–S Quantum Dots

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Synthesis from aqueous solutions and optical properties of Ag–In–S quantum dots

Cited by 11 publications

References 57 publications

Optical Characterization of Colloidal AgInS2 Quantum Dots Synthesized from Aqueous Solutions

Optical Characterization of Colloidal AgInS2 Quantum Dots Synthesized from Aqueous Solutions

One-Step Aqueous Synthesis of Anionic and Cationic AgInS2 Quantum Dots and Their Utility in Improving the Efficacy of ALA-Based Photodynamic Therapy

Synthesis and Optical Properties of Ag–Ga–S Quantum Dots

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Product

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One-Step Aqueous Synthesis of Anionic and Cationic AgInS₂ Quantum Dots and Their Utility in Improving the Efficacy of ALA-Based Photodynamic Therapy