Investigations on the photoinduced interaction of water soluble thioglycolic acid (TGA) capped CdTe quantum dots with certain porphyrins

Jhonsi, Mariadoss Asha; Renganathan, R.

doi:10.1016/j.jcis.2010.01.022

Cited by 88 publications

(50 citation statements)

References 58 publications

(53 reference statements)

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“…However, the addition of the positively charged free base TMPyP resulted in quenching of the QD 75 without any sensitised emission of the base and was attributed to electron transfer between the TMPyP free base porphyrin and the QD. 63 Our zinc porphyrin may be both readily oxidised or reduced {E o (P + /P) = 1.18 V and E o (P/P -) = -0.85V}. 42 The redox properties of CdTe have been shown to be size-dependent and 80 influenced by the nature of the capping ligand.…”

Section: Picosecond Transient Absorptionmentioning

confidence: 99%

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

et al. 2012

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The photophysical properties of 2.3 nm thioglycolic acid (TGA) coated CdTe quantum dots (QDs) prepared by a reflux method have been studied in the presence of a cationic meso-tetrakis(4-N-methylpyridyl) zinc porphyrin (ZnTMPyP4). Addition of the CdTe QDs to porphyrin in H 2 O results in a marked red-shift and hypochromism in the porphyrin absorption spectrum, indicative of a non-covalent binding interaction with the QD surface. Low equivalents of the quantum dot were required for complete quenching of the porphyrin fluorescence revealing that one quantum dot 10 may quench more than one porphyrin. Similarly addition of porphyrin to the quantum dot provided evidence for very efficient quenching of the CdTe photoluminescence, suggesting the formation of CdTe-porphyrin aggregates. Definitive evidence for such aggregates was gathered using small angle X-ray spectroscopy (SAXS). Ultrafast transient absorption data are consistent with very rapid photoinduced electron transfer (1.3 ps) and the resultant formation of a long-lived porphyrin species.

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Section: Picosecond Transient Absorptionmentioning

confidence: 99%

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

et al. 2012

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“…Fluorescence lifetime measurements are the most useful method for differentiating between static and dynamic quenching [32]. Figure 4 shows the fluorescence decay curves of CdTe QDs in the absence and presence of DPPH • .…”

Section: Resultsmentioning

confidence: 99%

Interaction of CdTe Quantum Dots with 2,2-Diphenyl-1-Picrylhydrazyl Free Radical: A Spectroscopic, Fluorimetric and Kinetic Study

2011

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The interaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH(·) free radical with thiol-capped CdTe quantum dots (QDs) has been studied by UV-vis spectroscopy, steady state and time resolved fluorescence measurements. Addition of DPPH(·) radical to CdTe QDs resulted in fluorescence quenching. The interaction occurs through static quenching as this was confirmed by fluorescence lifetime measurements. Time course absorption studies indicates that DPPH(·) may be reduced by interaction with QDs to the substituted hydrazine form (2,2-diphenyl-1-picrylhydrazine) DPPH-H. The mechanism of fluorescence quenching of CdTe QDs by DPPH(·) is proposed.

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“…where D (2.7 nm) was the size of CdTe QDs, and k (518 nm) was the wavelength of the absorption peak of CdTe QDs [6]. To purify the TGA-capped CdTe QDs, the free CdCl 2 and TGA were removed via dialysis for 24 h in 0.01 M NaOH solution by the dialysis membrane with a molecular weight of cutoff 7000.…”

Section: Synthesis and Characterization Of Tga-capped Cdte Qdsmentioning

confidence: 99%

“…CdTe QDs can be synthesized by a non-aqueous organometallic route at high temperature (e.g., 300°C) or an aqueous method at 100°C [4][5][6]. The synthesized QDs through nonaqueous organometallic routes usually need to undergo surface exchange with hydrophilic ligands in aqueous solution for biological applications.…”

Section: Introductionmentioning

confidence: 99%

Ligand exchange on the surface of cadmium telluride quantum dots with fluorosurfactant-capped gold nanoparticles: Synthesis, characterization and toxicity evaluation

Wang¹,

Zhang²,

Lu³

et al. 2014

Journal of Colloid and Interface Science

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a b s t r a c tCdTe quantum dots (QDs) can provide high-intensity and photostable luminescent signals when they are used as labeling materials for sensing trace amounts of bioanalytes. However, a major concern is whether the capping ligands of CdTe QDs cause toxic effects in living systems. In the current study, we address this problem through the complete ligand transformation of CdTe QDs from toxic thiolglycolic acid (TGA) to green citrate, which is attributed to the CdAS bond breaking and the AuAS bond formation. The highly efficient depletion of S atom from the surface of the CdTe QDs occurs after the addition of fluorosurfactant (FSN)-capped gold nanoparticles into TGA-capped CdTe QDs, accompanying with the rapid aggregation of FSN-capped gold nanoparticles via noncrosslinking mechanism in the presence of high salt. After the ligand transformation, negligible differences are observed on both photoluminescence spectra and luminescent quantum yield. In addition, the cytotoxicity of the original and new-born CdTe QDs is detected by measuring cell viability after the nanoparticle treatment. In comparison with the original TGA-capped QDs, the new-born CdTe QDs can induce minimal cytotoxicity against human hepatocellular liver carcinoma (HepG2) cells even at high dosages. Our study indicates that the extremely simple method herein opens up novel pathways for the synthesis of green CdTe QDs, and the as-prepared citrate-capped CdTe QDs might have great potential for biological labeling and imaging applications.

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Investigations on the photoinduced interaction of water soluble thioglycolic acid (TGA) capped CdTe quantum dots with certain porphyrins

Cited by 88 publications

References 58 publications

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

Interaction of CdTe Quantum Dots with 2,2-Diphenyl-1-Picrylhydrazyl Free Radical: A Spectroscopic, Fluorimetric and Kinetic Study

Ligand exchange on the surface of cadmium telluride quantum dots with fluorosurfactant-capped gold nanoparticles: Synthesis, characterization and toxicity evaluation

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