Practical Considerations, Challenges, and Limitations of Bioconjugation via Azide–Alkyne Cycloaddition

Pickens, Chad J.; Johnson, Stephanie N.; Pressnall, Melissa M.; Leon, Martin A.; Berkland, Cory

doi:10.1021/acs.bioconjchem.7b00633

Cited by 204 publications

(172 citation statements)

References 143 publications

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“…In our previous work, we used the copper‐catalyzed azide–alkyne cycloaddition;15a however, crosslinked polymers were obtained when the azide concentration exceeded 10 mol%. To prevent this deleterious side reaction, we employed the strain‐promoted azide–alkyne cycloaddition (SPAAC) that proceeds without a copper catalyst . This approach involved five linear steps to synthesize the strained alkyne fullerene derivative, with a 14% overall yield from commercial starting materials ( Scheme , pp.…”

Section: Resultsmentioning

confidence: 99%

Random Copolymers Outperform Gradient and Block Copolymers in Stabilizing Organic Photovoltaics

Chen

Song

Mueller

et al. 2019

Adv Funct Materials

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Recent advances have led to conjugated polymer-based photovoltaic devices with efficiencies rivaling amorphous silicon. Nevertheless, these devices become less efficient over time due to changes in active layer morphology, thereby hindering their commercialization. Copolymer additives are a promising approach toward stabilizing blend morphologies; however, little is known about the impact of copolymer sequence, composition, and concentration. Herein, the impact of these parameters is determined by synthesizing random, block, and gradient copolymers with a poly(3-hexylthiophene) (P3HT) backbone and side-chain fullerenes (phenyl-C 61 -butyric acid methyl ester (PC 61 BM)). These copolymers are evaluated as compatibilizers in photovoltaic devices with P3HT:PC 61 BM as the active layer. The random copolymer with 20 mol% fullerene side chains and at 8 wt% concentration in the blend gives the most stable morphologies. Devices containing the random copolymer also exhibit higher and more stable power conversion efficiencies than the control device. Combined, these studies point to the random copolymer as a promising new scaffold for stabilizing bulk heterojunction photovoltaics.

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Section: Resultsmentioning

confidence: 99%

Random Copolymers Outperform Gradient and Block Copolymers in Stabilizing Organic Photovoltaics

Chen

Song

Mueller

et al. 2019

Adv Funct Materials

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“…After stirring for 3 h, the reaction mixture was partially concentrated to remove the organic solvent and then poured into 100 mL of water. The aqueous phase was extracted with AcOEt (2 x 100 mL), and the combined organic phases were washed with saturated NaHCO 3 (100 mL), 5 % aqueous HCl solution (100 mL) and saturated NaCl (100 mL (1-(2-methoxy-(2-oxoethyl))(4-pyridin-1-ium))methylene)-7-(N,N-diethylamino)-4methyl-coumarin bromide (8). Methyl bromoacetate (140 µL, 1.51 mmol) was added to a solution of coumarin 2 6a (500 mg, 1.51 mmol) in AcOEt (60 mL 6, 166.8, 154.9, 153.2, 152.1, 149.6, 144.0, 127.0, 120.1, 118.0, 112.1, 110.4, 96.5, 78.2, 58.3, 53.0, 44.2, 18.5, 12.4 (1-(2-((3-azidopropyl)amino)-2-oxoethyl))(4-pyridin-1-ium))methylene) .…”

Section: Synthesis Of Compounds 9 and 10mentioning

confidence: 99%

Solid-Phase Approaches for Labeling Targeting Peptides with Far-Red Emitting Coumarin Fluorophores

et al. 2019

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Fluorophores based on organic molecules hold great potential for ligand-targeted imaging applications, particularly those operating in the optical window in biological tissues. In this work we have developed three straightforward solid-phase approaches based on amide-bond formation or Cu(I)-catalyzed azide-alkyne click (CuAAC) reaction for labelling octreotide peptide with far-red emitting coumarin-based COUPY dyes. First, the conjugatable versions of COUPY fluorophores incorporating the required functional groups (e.g., carboxylic acid, azide or alkyne) were synthesized and characterized. All of them were found fully compatible with Fmoc/tBu solid-phase peptide synthesis, which allowed the labeling of octreotide either through amide-bond formation or by CuAAC reaction. A near quantitative conversion was obtained after only 1 h of reaction at RT when using CuSO 4 and sodium ascorbate independently of the click chemistry approach used (azido-COUPY/alkynyl-peptide resin or alkynyl-COUPY/azido-peptide resin). COUPY-octreotide conjugates were found stable in cell culture medium as well as non-cytotoxic in HeLa cells, and their spectroscopic and photophysical properties were found similar to those of their parent coumarin dyes. Finally, the potential bioimaging applications of COUPY-octreotide conjugates were demonstrated by confocal microscopy through the visualization of living HeLa cells overexpressing somatostatin subtype-2 receptor.Owing to the potential of fluorophores based on organic molecules in ligand-targeted imaging applications, it is urgent to develop novel low molecular-weight fluorescent probes operating in the far-red and near-infrared (NIR) region, since only the use of non-toxic and high tissuepenetrating radiation will guarantee clinical translation in the next years. 3 Ideally, such fluorophores should be amenable to smart structural modifications to tune, on demand, photophysical and physicochemical properties, as well as to facilitate conjugation to a broad variety of targeting ligands (e.g., peptides, proteins, folic acid, monoclonal antibodies (mAb), etc.) by using efficient and chemoselective conjugation chemistries. Although many times forgotten, the biological properties of a targeting ligand should not be impaired by the fluorescent tag. This issue is particularly problematic in the case of short peptide sequences since uptake and subcellular localization may be strongly influenced by the fluorophore. 4 In the same way, some structural modifications of cyanine-based dyes have been reported to alter the mechanism of mAb when conjugated together, and non-specific hydrophobic interactions between Epidermal Growth Factor (EGF) receptor and the dye moiety in BODIPY-peptide conjugates were found to reduce peptide-receptor binding specificity. 5Hence, the choice of the fluorophore cannot be underestimated since constitutes a critical parameter in ligand-targeted imaging applications.Recently, we have developed a novel family of coumarin-based fluorophores, nicknamed COUPYs, with promising photoph...

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“…For instance, CuAAC applied for the conjugation of biomacromolecules requires the introduction of the reactive group to the protein/enzyme. This is often performed using heterofunctional linkers bearing NHS or maleimide groups that can react with amine or thiol groups present in the targeting biomolecule, thus deteriorating the “functionality‐to‐spacer‐ratio.” In general, careful selection of the appropriate linker for the introduction of an azide/alkyne to a system must be considered, as it will play a key role in the final properties of the system. In addition, the solubility and stability of the linker, as well as the potential effect of the resulting triazole in (biological) particle environments are critical parameters for the design of a suitable functionalization strategy …”

Section: Click Chemistry For Functionalization Of Reactive Particlesmentioning

confidence: 99%

Reactive Precursor Particles as Synthetic Platform for the Generation of Functional Nanoparticles, Nanogels, and Microgels

Gruber

Navarro

Klinger

2019

Adv Materials Inter

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Precise control of the chemical functionality of polymer nanoparticles is a key requirement in tailoring their (dynamic) colloidal properties toward advanced applications. However, current synthetic techniques are still limited in the versatility of chemical design and preparation of such functional colloidal nanomaterials. Two major challenges remain: First, various particle preparation methods are restricted in their functional group tolerance, thus hindering certain combinations of polymer backbones with specific functional groups. Second, the preparation of particles with different functionalities requires the synthesis of different particle batches. But this often results in a simultaneous variation of colloidal features. As a result, the accurate determination of important structure–property relations is still hindered. To address these restrictions, postmodification of preformed reactive particles is gaining more attention. This technique has evolved from polymer synthesis, where postpolymerization functionalization enables the introduction of a plethora of functional groups without changing the degree of polymerization and the molecular weight distribution. Similarly, modifying precursor particles enables the introduction of functional groups into particles while reducing variations in colloidal features, e.g., particle size and size distribution. This powerful synthetic method complements established procedures for functionalization of particle surfaces, thereby enabling the facile preparation of (multi‐)functional particle libraries, which will allow precise investigations of structure–property relations.

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Practical Considerations, Challenges, and Limitations of Bioconjugation via Azide–Alkyne Cycloaddition

Cited by 204 publications

References 143 publications

Random Copolymers Outperform Gradient and Block Copolymers in Stabilizing Organic Photovoltaics

Random Copolymers Outperform Gradient and Block Copolymers in Stabilizing Organic Photovoltaics

Solid-Phase Approaches for Labeling Targeting Peptides with Far-Red Emitting Coumarin Fluorophores

Reactive Precursor Particles as Synthetic Platform for the Generation of Functional Nanoparticles, Nanogels, and Microgels

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