Compact and highly stable quantum dots through optimized aqueous phase transfer

Tamang, Sudarsan; Beaune, Grégory; Poillot, Cathy; Waard, Michel De; Texier, Isabelle; Reiß, Peter

doi:10.1117/12.873805

Cited by 7 publications

(4 citation statements)

References 15 publications

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“…Commonly used thiol or carboxyl group containing molecules that are utilized in nanoparticle synthesis as stabilizers like cysteamine (Cys) [ 11 ], 3-mercaptopropionic acid (MPA) [ 45 ], ethanethiol (ET) and acetate (Ac) were modeled as capping ligands and compared (ET and Ac are used as computational inexpensive molecules that represent the influence of long chain thiols or fatty acids like 1-dodecanethiol [ 46 ], oleic acid [ 47 ] or stearic acid [ 48 ] that are often used in nanoparticle synthesis). Figure 10 shows the evolution of the computed DOS in ZnS nanocrystals passivated with different ligands.…”

Section: Resultsmentioning

confidence: 99%

Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

2020

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The linear photochemical response of materials depends on two critical parameters: the size of the optical band gap determines the onset of optical excitation, whereas the absolute energetic positions of the band edges define the reductive or oxidative character of photo-generated electrons and holes. Tuning these characteristics is necessary for many potential applications and can be achieved through changes in the bulk composition or particle size, adjustment of the surface chemistry or the application of electrostatic fields. In this contribution the influence of surface chemistry and fields is investigated systematically with the help of standard DFT calculations for a typical case, namely composites prepared from ZnS quantum dots and functionalized carbon nanotubes. After comparing results with existing qualitative and quantitative experimental data, it is shown conclusively, that the details of the surface chemistry (especially defects) in combination with electrostatic fields have the largest influence. In conclusion, the development of novel or improved photoresponsive materials therefore will have to integrate a careful analysis of the interplay between surface chemistry, surface charges and interaction with the material environment or substrate.

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Section: Resultsmentioning

confidence: 99%

Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

2020

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“…They further found the QY of synthesized CdSe/ZnS core-shell QDs capped with MPA was comparable to that of trioctylphosphine oxide (TOPO)-capped QDs while the QY of MPA-capped CdSe-ZnS QDs using ligand exchange method was five-fold lower. Tamang et al [ 46 ] found that pH played an important role in increasing stability of InP/ZnS QDs during an aqueous phase transfer procedure. The thiol group of a water-soluble ligand is deprotonated at high pH, and thiolate has been shown to bind the QDs surface more strongly than thiol [ 47 ].…”

Section: Direct Ligand Exchangementioning

confidence: 99%

Overview of Stabilizing Ligands for Biocompatible Quantum Dot Nanocrystals

Zhang

Clapp

2011

Sensors

165

144

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Luminescent colloidal quantum dots (QDs) possess numerous advantages as fluorophores in biological applications. However, a principal challenge is how to retain the desirable optical properties of quantum dots in aqueous media while maintaining biocompatibility. Because QD photophysical properties are directly related to surface states, it is critical to control the surface chemistry that renders QDs biocompatible while maintaining electronic passivation. For more than a decade, investigators have used diverse strategies for altering the QD surface. This review summarizes the most successful approaches for preparing biocompatible QDs using various chemical ligands.

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“…InP/ZnS QDs are prepared in octadecene using phosphine gas as the phosphorus precursor and capped with a ZnS shell using a method we reported earlier . Prior to the grafting of the water-soluble CA, a phase transfer reaction is performed using penicillamine at pH 9 in a 1:1 mixture of water and chloroform (reaction time 2 h, transfer yield 60%) . The InP/ZnS QDs capped with penicillamine (QD.Pen) provide a versatile platform for grafting of lanthanide chelates and/or other bioprobes.…”

Section: Resultsmentioning

confidence: 99%

Cell-Permeable Ln(III) Chelate-Functionalized InP Quantum Dots As Multimodal Imaging Agents

et al. 2011

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Quantum dots (QDs) are ideal scaffolds for the development of multimodal imaging agents, but their application in clinical diagnostics is limited by the toxicity of classical CdSe QDs. A new bimodal MRI/optical nanosized contrast agent with high gadolinium payload has been prepared through direct covalent attachment of up to 80 Gd(III) chelates on fluorescent nontoxic InP/ZnS QDs. It shows a high relaxivity of 900 mM(-1) s(-1) (13 mM(-1 )s(-1) per Gd ion) at 35 MHz (0.81 T) and 298 K, while the bright luminescence of the QDs is preserved. Eu(III) and Tb(III) chelates were also successfully grafted to the InP/ZnS QDs. The absence of energy transfer between the QD and lanthanide emitting centers results in a multicolor system. Using this convenient direct grafting strategy additional targeting ligands can be included on the QD. Here a cell-penetrating peptide has been co-grafted in a one-pot reaction to afford a cell-permeable multimodal multimeric MRI contrast agent that reports cellular localization by fluorescence and provides high relaxivity and increased tissue retention with respect to commercial contrast agents.

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Compact and highly stable quantum dots through optimized aqueous phase transfer

Cited by 7 publications

References 15 publications

Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

Tuning the Optical Band Gap of Semiconductor Nanocomposites—A Case Study with ZnS/Carbon

Overview of Stabilizing Ligands for Biocompatible Quantum Dot Nanocrystals

Cell-Permeable Ln(III) Chelate-Functionalized InP Quantum Dots As Multimodal Imaging Agents

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