Synthesis of random terpolymers bearing multidentate imidazole units and their use in functionalization of cadmium sulfide nanowires

Viswanath, Anand; Paudel, Pravin; Kittikhunnatham, Preecha; Green, Alexandra N.; Greytak, Andrew B.; Benicewicz, Brian C.

doi:10.1039/c5py00685f

Cited by 6 publications

(11 citation statements)

References 33 publications

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“…While a lot of work has been devoted to anchor group modification of the polymeric ligands, only few variations have been reported concerning the hydrophilic part of the polymer. − The vast majority of published studies have so far solely used poly(ethylene glycol) (PEG). − In order to minimize nonspecific interactions of the functionalized QDs in the biological environment, polymers with stealth -like properties are needed. This explains why PEG is such a prominent candidate as hydrophilic ligand for QD modification.…”

Section: Introductionmentioning

confidence: 99%

Multidentate Polysarcosine-Based Ligands for Water-Soluble Quantum Dots

et al. 2016

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We describe the synthesis of heterotelechelic polysarcosine polymers and their use as multidentate ligands in the preparation of stable water-soluble quantum dots (QDs). Orthogonally functionalized polysarcosine with amine and dibenzocyclooctyl (DBCO) end groups is obtained by ringopening polymerization of N-methylglycine N-carboxyanhydride with DBCO amine as initiator. In a first postpolymerization modification step, the future biological activity of the polymeric ligands is adjusted by modification of the amine terminus. Then, in a second postpolymerization modification step, azide functionalized di-and tridentate anchor compounds are introduced to the DBCO terminus of the polysarcosine via strain-promoted azide−alkyne cycloaddition (SPAAC). Through the separate synthesis of the anchor compounds, it is possible to ensure reproducible introduction of a well-defined number of multiple anchor groups to all polymers studied. Finally, the obtained multidentate polymeric ligands are successfully used in the ligand exchange procedures to yield stable, water-soluble QDs. As polysarcosine-based ligands can provide biocompatibility, prevent nonspecific interactions, and simultaneously enable specific targeting, the systems presented here are promising candidates to provide QDs well suitable for ex vivo analytics or bioimaging.

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Section: Introductionmentioning

confidence: 99%

Multidentate Polysarcosine-Based Ligands for Water-Soluble Quantum Dots

et al. 2016

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“…The integrated peak area above the baseline set by the background regions at each end of the plot was used to define the intensity. We used a similar approach to study inorganic nanowires . Details of the microscope configuration are shown in Figure S8.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…In addition, this technique can be applied over a large range of guest loading factors. Such analysis is particularly well-suited to crystals with quasi-1D shapes, such as semiconductor nanowires and the microcrystals studied here because of the possibility of averaging signals along the 1D axis …”

Section: Introductionmentioning

confidence: 99%

Fluorescence Polarization Measurements to Probe Alignment of a Bithiophene Dye in One-Dimensional Channels of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals

et al. 2017

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This thesis describes the use of polarized fluorescence microscopy to directly probe guest molecule orientation in bis-urea macrocycle crystals. These macrocycles assemble to afford one-dimensional (1D) microchannels ∼9 Å in diameter that have previously been shown to exhibit normal Fickian diffusion and induce selective reactivity among the confined guest molecules. In the present work, we take advantage of the quasi-1D morphology of fiber-like microcrystals with the extended dimension corresponding to the channel axis to measure excitation and emission polarization values for a bithiophene guest. Guest fluorescence is shown to be polarized along the fiber axis with emission polarization values up to 0.729, indicating a high degree of orientational order within the 1D channels. The observed behavior is consistent with calculated results for the guest orientation and electronic transition dipole moment. The results indicate the value of functional fluorescent probes as a measure of guest confinement in low-dimensional environments. vi

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“…The polymer-capped QDs (MA-PIL-QDs) were stable and exhibited negligible nonspecific binding and cytotoxicity to human endothelial cells over a range of polymer chain lengths . Ternary co-polymers with methoxy- and amine-terminated PEG sidechains enabled selective labeling of targets on cell surfaces via copper-free click chemistry and were also used to demonstrate association of MA-PILs to CdS nanowires through the use of a covalently linked fluorescent dye tracer. , …”

Section: Introductionmentioning

confidence: 99%

“…18 Ternary co-polymers with methoxy-and amine-terminated PEG sidechains enabled selective labeling of targets on cell surfaces via copper-free click chemistry and were also used to demonstrate association of MA-PILs to CdS nanowires through the use of a covalently linked fluorescent dye tracer. 19,28 In the present study, we directly examine the stability of MA-PIL-capped CdSe/Cd x Zn 1−x S core/shell QDs toward small thiol molecule competition, using glutathione at biologically relevant concentrations under neutral conditions in phosphate-buffered saline (PBS, pH 7.3−7.5). The core/ shell QDs were prepared by selective ion layer addition and reaction (SILAR) and purified by gel permeation chromatography (GPC) in toluene prior to ligand exchange to install the MA-PILs, according to previously described methods.…”

Section: Introductionmentioning

confidence: 99%

Multiply-Binding Polymeric Imidazole Ligands: Influence of Molecular Weight and Monomer Sequence on Colloidal Quantum Dot Stability

et al. 2018

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This study addresses the colloidal stability of polymer-coated core/shell CdSe/Cd x Zn 1−x S quantum dots (QDs) in the presence of L-glutathione (GSH) under neutral conditions by means of photoluminescence (PL) and absorption spectroscopy. A reversible addition−fragmentation chain-transfer-mediated synthesis was employed to produce co-polymer ligands with different molecular weights in block and random sequences. Poly(ethylene glycol) sidechains were incorporated on a methacrylate backbone for solubility in phosphate-buffered saline. Imidazole-bearing histamine sidechains were installed postsynthetically to facilitate binding to the QD surface. Introduction of L-glutathione, an endogenous monothiol, to aqueous solutions of the polymer-coated QDs led to an increase in PL quantum yield, indicating an interaction between the QD and glutathione. The PL change was greatly diminished for block co-polymers versus random co-polymers of similar molecular weight and composition. Additionally, higher ligand populations were found upon initial purification of block co-polymer-coated QDs versus the random co-polymers. We demonstrate that glutathione does not significantly displace the polymer ligands from the QD surface, suggesting that PL changes are driven primarily through ligand association. The block copolymers are more resistant to glutathione association, and indeed stronger binders, than the randomly ordered co-polymers, with higher-molecular-weight contributing to improved stability in both cases. To the best of our knowledge, this is the first study to directly compare the relative stability of block and random polymeric imidazole ligands and should aid in developing more stable ligand-exchanged QDs for bioimaging and biosensing, especially for in vivo and intracellular applications.

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Synthesis of random terpolymers bearing multidentate imidazole units and their use in functionalization of cadmium sulfide nanowires

Abstract: This work reports on a new synthesis method for random ternary copolymers that are shown to tether a molecular dye payload to cadmium sulfide nanowires in aqueous solution.

Cited by 6 publications

References 33 publications

Multidentate Polysarcosine-Based Ligands for Water-Soluble Quantum Dots

Multidentate Polysarcosine-Based Ligands for Water-Soluble Quantum Dots

Fluorescence Polarization Measurements to Probe Alignment of a Bithiophene Dye in One-Dimensional Channels of Self-Assembled Phenylethynylene Bis-Urea Macrocycle Crystals

Multiply-Binding Polymeric Imidazole Ligands: Influence of Molecular Weight and Monomer Sequence on Colloidal Quantum Dot Stability

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