Fluorescence modulation of cadmium sulfide quantum dots by azobenzene photochromic switches

Javed, Hina; Fatima, Kaneez; Akhter, Zareen; Nadeem, Muhammad Arif; Siddiq, Muhammad; Iqbal, Azhar

doi:10.1098/rspa.2015.0692

Cited by 19 publications

(15 citation statements)

References 21 publications

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“…The FTIR spectrum of QD-Bare (Fig. 1A) shows a broad peak from 3185 to 3320 cm −1 representing OH stretching vibrations, and complex deformations centered at 1629, 1538,1409, 1006, and 665 cm −1 , which represent C]O asymmetric stretching, NH bending, C]O symmetric stretching, CeH bending, and CdS-stretching, respectively on CdS-QD surface (Kotkata et al, 2009;Javed et al, 2016). The FTIR of QD-TOPO reveals a characteristic peak corresponding to eCH 2 stretching at 2931 cm −1 present in TOPO molecule (Young et al, 2008), and a broad peak for eOH stretching at 3316 cm −1 .…”

Section: Characterization Of the Cds-qdsmentioning

confidence: 99%

Surface coating determines the response of soybean plants to cadmium sulfide quantum dots

Majumdar

Villani

et al. 2019

NanoImpact

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Quantum dots (QDs) are used in an array of applications from electronic devices to medicine, leading to environmental release and accumulation in landfills and agricultural soils. However, their effects on plants have been least studied among other engineered nanomaterials. In the current study, soybean seedlings were exposed to 50-200 mg/L cadmium sulfide quantum dots (CdS-QDs) to elucidate their bioaccumulation and biological response in comparison to Cd 2+ ions and bulk-CdS. To understand the role of surface coatings on QD stability, uptake, translocation, subcellular localization and cellular response, bare CdS-QDs were capped with ligands varying in polarity and surface charge. Four common ligands, including trioctylphosphine oxide, polyvinylpyrrolidone, mercaptoacetic acid, and glycine were used to synthesize QD-TOPO, QD-PVP, QD-MAA, and QD-GLY, respectively. In aqueous suspension, QD-MAA particles were most stable, maintaining their size at 332 nm with least Cd 2+ dissolution (9%) after 14 d, whereas QD-TOPO formed large aggregates of size 3861 nm with 27% Cd 2+ dissolution. Upon exposure to 100 mg/L bare and coated CdS-QDs in vermiculite for 14 d, soybean roots accumulated Cd, ranging from 568 (QD-MAA) to 1010 (QD-PVP) μg/g tissue dry weight (DW); statistically equivalent to bulk-CdS treatment (639 μg/g DW). In the roots, Cd from CdCl 2 , bulk-CdS, QD-MAA and QD-GLY accumulated primarily in the cell wall (~40-55%) followed by organelles (28-40%), suggesting apoplastic pathway; whereas in QD-TOPO, dissolved Cd 2+ ions accumulated mainly in the membranes. The exception was QD-PVP, which sequestered Cd mainly in the organelles (49%) in roots, potentially via symplastic pathway and translocated to shoots, resulting in reduced leaf biomass. Results suggested that peroxidases play the predominant role in quenching the oxidative stress caused by CdS-QD exposure. At the highest CdS-QD treatment (200 mg/L), root lignification allowed the plants to restrict Cd accumulation, except in QD-PVP, where lignification was reduced by 21% leading to higher Cd content in shoots. Increased amino acid content in the leaves was noted as a stress tolerance mechanism by the plants exposed to 200 mg/L QD treatments. This study highlights the significant influence that surface coating exerts on QDs fate and effects in a planted system.

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Section: Characterization Of the Cds-qdsmentioning

confidence: 99%

Surface coating determines the response of soybean plants to cadmium sulfide quantum dots

Majumdar

Villani

et al. 2019

NanoImpact

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“…The photoluminescence study of a material describes the ability of migration, separation and recombination of photoinduced charge carriers [66,67]. CdS semiconductor nanomaterials are currently of great interest for their unique optical properties [68][69][70][71]. The photoluminescence studies for CdS NPs and RGO-CdS nanocomposites are displayed by Fig.…”

Section: Photocatalytic Mechanismmentioning

confidence: 99%

Exploration of photoreduction ability of reduced graphene oxide–cadmium sulphide hetero-nanostructures and their intensified activities against harmful microbes

et al. 2021

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Fabrication of effective photocatalyst using semiconductors and graphene or reduced graphene oxide has been regarded as one of the most promising task to attenuate the environmental pollution. This paper reports the synthesis of different nanocomposites of reduced graphene oxide-cadmium sulfide (RGO-CdS) with varying weight ratio of RGO by simple reflux condensation reaction, during which the reduction of graphene oxide (GO) and formation of CdS nanoparticles occur simultaneously. The combination of CdS nanoparticles (NPs) with the optimum amount of RGO gives a noticeable effect on the properties of the synthesized hybrid nanocomposites, such as enhanced optical, photocatalytic properties. The microscopic studies proved that with the increasing RGO content in the nanocomposites, the particle size decreases and got different shapes. These nanocomposites have been investigated separately as nanocatalyst for the reduction of Cr(VI) to Cr(III) in the presence of visible light irradiation and the catalytic activity depends on the pH of the medium and also the particle size of the CdS NPs which are supported by the band gap energy derived from Tauc's equation. The significant increase in photocatalytic performance of the RGO-CdS nanocomposite was attributed to high electron conductivity of the CdS NPs and RGO surface which facilitates charge separation and prolongs the lifetime of photogenerated electron-hole pairs by decreasing the recombination rate. Antibacterial and antiprotozoal activities have been investigated to determine the efficiency of these RGO-CdS nanocomposites on different bacterial and protozoan strains.

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“…Colloidal CdS quantum dots capped with thioglycolic acid (TGA) were prepared using previously published procedures, wherein 25 mL of DMSO was purged with Ar (g) for 30 min. Following the purge, 1.25 mmol of Cd(NO 3 ) 2 ·4H 2 O was added to the solution, the pH adjusted to 9.0 via the addition of aqueous 0.1 M NaOH, and the mixture heated to 70 °C while stirring under nitrogen.…”

Section: Methodsmentioning

confidence: 99%

Improving the Efficiency of the Mn^2+/3+ Couple in Quantum Dot Solar Cells: The Role of Spin Crossover

et al. 2018

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In this study, we present the synthesis of a family of first-row transition metal redox mediators based on the bis[hydrotris(pyrazolyl)]borate manganese(II/III) (MnTp2) redox couple. Using cyclic voltammetry, the electrochemical properties and characteristic spin crossover inherent in this class of metal complexes were analyzed. From the electrochemical analysis the standard heterogeneous rate constant (k s,h) was estimated. These constants were 1–2 orders of magnitude lower than other outer-sphere redox couples, such as Co(bpy)3 2+/3+ with k s,h values decreasing from 6.39 (± 0.7) × 10–3 cm/s in Co(bpy)3 to 1.60 (± 0.3) × 10–5 cm/s in bis[hydrotris(4-ethylpyrazolyl)]borate manganese(II/III). It was theorized that the drastic reduction in the rate of electron transfer could be used to increase the lifetimes of the injected electrons in quantum dot sensitized solar cells (QDSSCs). Indeed, this was found to be the case with the slope of open-circuit voltage decay measurements being an order of magnitude lower in the Mn-based redox couples, compared to Co(bpy)3 when using cells prepared under the same conditions. This increase led us to then focus on optimizing the electrolyte solvent to assess the current–voltage characteristics of cells prepared using the MnTp2 family of redox mediators. These cells displayed enhanced power conversion efficiencies when compared to Co(bpy)3 despite poor diffusion throughout the nanostructured TiO2 film. Analysis of the quenching rate constant via Stern–Volmer quenching analysis suggested that the MnTp2 family of redox mediators possesses an adequate ability to regenerate the quantum dot sensitizer, with values of k q being on similar orders of magnitude as other Co- and Cu-based redox couples employed in dye-sensitized solar cells. Ultimately, it was concluded that the increase in the lifetime of the injected electron, working in concert with increased open-circuit voltage potentials, was the source of the significantly improved power conversion efficiencies.

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Fluorescence modulation of cadmium sulfide quantum dots by azobenzene photochromic switches

Cited by 19 publications

References 21 publications

Surface coating determines the response of soybean plants to cadmium sulfide quantum dots

Surface coating determines the response of soybean plants to cadmium sulfide quantum dots

Exploration of photoreduction ability of reduced graphene oxide–cadmium sulphide hetero-nanostructures and their intensified activities against harmful microbes

Improving the Efficiency of the Mn^2+/3+ Couple in Quantum Dot Solar Cells: The Role of Spin Crossover

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Fluorescence modulation of cadmium sulfide quantum dots by azobenzene photochromic switches

Cited by 19 publications

References 21 publications

Surface coating determines the response of soybean plants to cadmium sulfide quantum dots

Surface coating determines the response of soybean plants to cadmium sulfide quantum dots

Exploration of photoreduction ability of reduced graphene oxide–cadmium sulphide hetero-nanostructures and their intensified activities against harmful microbes

Improving the Efficiency of the Mn2+/3+ Couple in Quantum Dot Solar Cells: The Role of Spin Crossover

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Improving the Efficiency of the Mn^2+/3+ Couple in Quantum Dot Solar Cells: The Role of Spin Crossover