Polarity-tunable and wavelength-tunable bacteriochlorins bearing a single carboxylic acid or NHS ester. Use in a protein bioconjugation model system

Jiang, Jianbing; Chen, Chih-Yuan; Zhang, Nuonuo; Vairaprakash, Pothiappan; Lindsey, Jonathan S.

doi:10.1039/c4nj01340a

Cited by 13 publications

(27 citation statements)

References 68 publications

(114 reference statements)

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“…47,48 Because the ionic groups impart solubility in water but not (typically) in non-aqueous solvents, the polar group typically must be installed or unveiled in the last synthetic step, whereupon purification often entails merely washing the product with solvents. Moreover, the preparation of an activated ester (for bioconjugation) in the presence of ionic groups such as phosphates, phosphonates, and carboxylates can result in deleterious cross-reaction.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the preparation of an activated ester (for bioconjugation) in the presence of ionic groups such as phosphates, phosphonates, and carboxylates can result in deleterious cross-reaction. 47 The PEG group is an attractive alternative to these ionic species. 49 The PEG group is nonionic, is commercially available in various lengths 27 (monodisperse or polydisperse) with a single derivatizable handle, 25,27,50,51 and is soluble in water as well as a variety of organic solvents.…”

Section: Introductionmentioning

confidence: 99%

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Bioconjugatable, PEGylated hydroporphyrins for photochemistry and photomedicine. Narrow-band, red-emitting chlorins

et al. 2016

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Chromophores that absorb and emit in the red spectral region (600–700 nm), are water soluble, and bear a bioconjugatable tether are relatively rare yet would fulfill many applications in photochemistry and photomedicine. Here, three molecular designs have been developed wherein stable synthetic chlorins – analogues of chlorophylls – have been tailored with PEG groups for use in aqueous solution. The designs differ with regard to order of the installation (pre/post-formation of the chlorin macrocycle) and position of the PEG groups. Six PEGylated synthetic chlorins (three free bases, three zinc chelates) have been prepared, of which four are equipped with a bioconjugatable (carboxylic acid) tether. The most effective design for aqueous solubilization entails facial encumbrance where PEG groups project above and below the plane of the hydrophobic disk-like chlorin macrocycle. The chlorins possess strong absorption at ~400 nm (B band) and in the red region (Qy band); regardless of wavelength of excitation, emission occurs in the red region. Excitation in the ~400 nm region thus provides an effective Stokes shift of >200 nm. The four bioconjugatable water-soluble chlorins exhibit Qy absorption/emission in water at 613/614, 636/638, 698/700 and 706/710 nm. The spectral properties are essentially unchanged in DMF and water for the facially encumbered chlorins, which also exhibit narrow Qy absorption and emission bands (full-width-at-half maximum of each <25 nm). The water-solubility was assessed by absorption spectroscopy over the concentration range ~0.4 μM – 0.4 mM. One chlorin was conjugated to a mouse polyclonal IgG antibody for use in flow cytometry with compensation beads for proof-of-principle. The conjugate displayed a sharp signal when excited by a violet laser (405 nm) with emission in the 620–660 nm range. Taken together, the designs described herein augur well for development of a set of spectrally distinct chlorins with relatively sharp bands in the red region.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bioconjugatable, PEGylated hydroporphyrins for photochemistry and photomedicine. Narrow-band, red-emitting chlorins

et al. 2016

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“…The crude reaction mixture was not separable by column chromatography, and was used directly in the next step. The Suzuki coupling reaction with partner 12 38 gave the corresponding 3,5-diaryl-15-(carboxyaryl)bacteriochlorin 13 in 31% yield from two steps. Upon treatment of 40% TFA in CH 2 Cl 2 , four Boc groups were removed smoothly, as well as the tert -butyl protecting group.…”

Section: Resultsmentioning

confidence: 99%

“…Following a reported procedure, 38 a mixture of 16 (50. mg, 40. µmol), Pd 2 (dba) 3 (15 mg, 18 µmol, 0.45 equiv), and P( o -tol) 3 (30. mg, 95 µmol, 2.4 equiv) was dried under high vacuum in a Schlenk flask for 1 h. Toluene (2.6 mL) and TEA (1.3 mL) (both were bubbled with argon for 1 h) were added and the resulting mixture was degassed by three freeze-pump-thaw cycles. 6-Heptynoic acid ( 17 , 50 µL, 0.40 mmol, 10 equiv) was added.…”

Section: Methodsmentioning

confidence: 99%

Bioconjugatable, PEGylated hydroporphyrins for photochemistry and photomedicine. Narrow-band, near-infrared-emitting bacteriochlorins

et al. 2016

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Synthetic bacteriochlorins absorb in the near-infrared (NIR) region and are versatile analogues of natural bacteriochlorophylls. The utilization of these chromophores in energy sciences and photomedicine requires the ability to tailor their physicochemical properties, including the incorporation of units to impart water solubility. Herein, we report the synthesis, from two common bacteriochlorin building blocks, of five wavelength-tunable, bioconjugatable and water-soluble bacteriochlorins along with two non-bioconjugatable benchmarks. Each bacteriochlorin bears short polyethylene glycol (PEG) units as the water-solubilizing motif. The PEG groups are located at the 3,5-positions of aryl groups at the pyrrolic β-positions to suppress aggregation in aqueous media. A handle containing a single carboxylic acid is incorporated to allow bioconjugation. The seven water-soluble bacteriochlorins in water display Qy absorption into the NIR range (679–819 nm), sharp emission (21–36 nm full-width-at-half-maximum) and modest fluorescence quantum yield (0.017–0.13). Each bacteriochlorin is neutral (non-ionic) yet soluble in organic (e.g., CH2Cl2, DMF) and aqueous solutions. Water solubility was assessed using absorption spectroscopy by changing the concentration ∼1000-fold (190–690 µM to 0.19–0.69 µM) with a reciprocal change in pathlength (0.1–10 cm). All bacteriochlorins showed excellent solubility in water, except for a bacteriochlorin–imide that gave slight aggregation at higher concentrations. One bacteriochlorin was conjugated to a mouse polyclonal IgG antibody for use in flow cytometry with compensation beads for proof-of-principle. The antibody conjugate of B2-NHS displayed a sharp signal upon ultraviolet laser excitation (355 nm) with NIR emission measured with a 730/45 nm bandpass filter. Overall, the study gives access to a set of water-soluble bacteriochlorins with desirable photophysical properties for use in multiple fields.

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“…The 5methoxy bacteriochlorin readily undergoes bromination regioselectively at the 15-position [33]; the resulting 15-bromobacteriochlorin (IIIa) can be subjected to Suzuki or Sonogashira coupling reactions to install a single tether. The ability to install a single tether in this manner is quite valuable for subsequent derivatization purposes [34], and to date has not been achieved in any other rational manner. By contrast, the inherent nature of the condensation that forms the bacteriochlorin results in symmetric substitution in the two pyrrole rings (i.e.…”

Section: Introductionmentioning

confidence: 99%

Elaboration of an unexplored substitution site in synthetic bacteriochlorins

Zhang

Reddy

Jiang

et al. 2015

J. Porphyrins Phthalocyanines

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The ability to introduce substituents at designated sites about the perimeter of synthetic bacteriochlorins -analogs of bacteriochlorophylls of bacterial photosynthesis -remains a subject of ongoing study. Here, the self-condensation of a dihydrodipyrrin-dioxolane affords a 5-[2-(trimethylsiloxy) ethoxy]bacteriochlorin. Like a 5-methoxybacteriochlorin, the latter undergoes regioselective bromination at the 15-position, directed by the distal 5-alkoxy group. On the other hand, attempted bromination of a bacteriochlorin bearing a 5-(2-hydroxyethoxy) group resulted in intramolecular ether formation with the adjacent b-pyrroline position to give an annulated dioxepine ring (confirmed by single-crystal X-ray structural analysis). The hydroxyethoxy group at the 5-position can be derivatized by acylation. In addition, the installation of auxochromes (methoxycarbonyl, phenylethynyl) at the b-pyrrole rings causes a substantial bathochromic shift of the long-wavelength absorption band (812 nm) and companion fluorescence emission band (821 nm). Taken together, the modification of the 5-substituent complements existing methods for installing a single substituent on the bacteriochlorin macrocycle. J. Porphyrins Phthalocyanines 2015.19:887-902. Downloaded from www.worldscientific.com by EMORY UNIVERSITY on 07/30/15. For personal use only. G1 G2 2 A J K Scheme 5. Proposed mechanism leading to the 5-(2-alkoxyethoxy)bacteriochlorin J (top) and balanced equation (bottom) J. Porphyrins Phthalocyanines 2015.19:887-902. Downloaded from www.worldscientific.com by EMORY UNIVERSITY on 07/30/15. For personal use only.

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Polarity-tunable and wavelength-tunable bacteriochlorins bearing a single carboxylic acid or NHS ester. Use in a protein bioconjugation model system

Abstract: 10 new near-infrared absorbing bacteriochlorins (soluble in aqueous or membranous media) are equipped for protein bioconjugation.

Cited by 13 publications

References 68 publications

Bioconjugatable, PEGylated hydroporphyrins for photochemistry and photomedicine. Narrow-band, red-emitting chlorins

Bioconjugatable, PEGylated hydroporphyrins for photochemistry and photomedicine. Narrow-band, red-emitting chlorins

Bioconjugatable, PEGylated hydroporphyrins for photochemistry and photomedicine. Narrow-band, near-infrared-emitting bacteriochlorins

Elaboration of an unexplored substitution site in synthetic bacteriochlorins

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