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Porphyrin and Tetrabenzoporphyrin Dendrimers: Tunable Membrane-Impermeable Fluorescent pH Nanosensors

Finikova, Olga; Galkin, Alexander LU ; Rozhkov, Vladimir; Cordero, Maria; Hägerhäll, Cecilia LU and Vinogradov, Sergei (2003) In Journal of the American Chemical Society 125(16). p.4882-4893
Abstract
The pH dependencies of the UV-vis and fluorescent spectra of new water-soluble dendritic porphyrins and tetrabenzoporphyrins were studied. Because of extended -conjugation and nonplanar distortion, the absorption and the emission bands of tetraaryltetrabenzoporphyrins (Ar4TBP) are red-shifted and do not overlap with those of regular tetraarylporphyrins (Ar4P). When encapsulated inside dendrimers with hydrophilic outer layers, Ar4Ps and Ar4TBPs become water soluble and can serve as pH indicators, with pK's adjustable by the peripheral charges on the dendrimers. Two new dendritic porphyrins, Gen 4 polyglutamic porphyrin dendrimer H2P-Glu4OH (1) with 64 peripheral carboxylates and Gen 1 poly(ester amide) Newkome-type tetrabenzoporphyrin... (More)
The pH dependencies of the UV-vis and fluorescent spectra of new water-soluble dendritic porphyrins and tetrabenzoporphyrins were studied. Because of extended -conjugation and nonplanar distortion, the absorption and the emission bands of tetraaryltetrabenzoporphyrins (Ar4TBP) are red-shifted and do not overlap with those of regular tetraarylporphyrins (Ar4P). When encapsulated inside dendrimers with hydrophilic outer layers, Ar4Ps and Ar4TBPs become water soluble and can serve as pH indicators, with pK's adjustable by the peripheral charges on the dendrimers. Two new dendritic porphyrins, Gen 4 polyglutamic porphyrin dendrimer H2P-Glu4OH (1) with 64 peripheral carboxylates and Gen 1 poly(ester amide) Newkome-type tetrabenzoporphyrin dendrimer H2TBP-Nw1OH (2) with 36 peripheral carboxylates, were synthesized and characterized. The pK's of the encapsulated porphyrins (pKH2P-Glu4OH = 6.2 and pKH2TBP-Nw1OH = 6.3) were found to be strongly influenced by the dendrimers, revealing significant electrostatic shielding of the cores by the peripheral charges. The titration curves obtained by differential excitation using the mixtures of the dendrimers were shown to be identical to those determined for the dendrimers individually. Due to their peripheral carboxylates and nanometric molecular size, porphyrin dendrimers cannot penetrate through phospholipid membranes. Dendrimer 1 was captured inside phospholipid liposomes, which were suspended in a solution containing dendrimer 2. No response from 1 was detected upon pH changes in the bulk solution, while the response from 2 was predictably strong. When proton channels were created in the liposome walls, both compounds responded equally to the bulk pH changes. These results suggest that porphyrin dendrimers can be used as fluorescent pH indicators for proton gradient measurements. (Less)
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organization
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type
Contribution to journal
publication status
published
subject
in
Journal of the American Chemical Society
volume
125
issue
16
pages
4882 - 4893
publisher
The American Chemical Society
external identifiers
  • pmid:12696908
  • wos:000182331800048
  • scopus:0242515825
ISSN
1520-5126
DOI
10.1021/ja0341687
language
English
LU publication?
yes
id
de92ae45-df0a-42ac-ac63-6e5559096d7e (old id 124612)
date added to LUP
2007-07-05 09:13:29
date last changed
2018-09-23 04:13:14
@article{de92ae45-df0a-42ac-ac63-6e5559096d7e,
  abstract     = {The pH dependencies of the UV-vis and fluorescent spectra of new water-soluble dendritic porphyrins and tetrabenzoporphyrins were studied. Because of extended -conjugation and nonplanar distortion, the absorption and the emission bands of tetraaryltetrabenzoporphyrins (Ar4TBP) are red-shifted and do not overlap with those of regular tetraarylporphyrins (Ar4P). When encapsulated inside dendrimers with hydrophilic outer layers, Ar4Ps and Ar4TBPs become water soluble and can serve as pH indicators, with pK's adjustable by the peripheral charges on the dendrimers. Two new dendritic porphyrins, Gen 4 polyglutamic porphyrin dendrimer H2P-Glu4OH (1) with 64 peripheral carboxylates and Gen 1 poly(ester amide) Newkome-type tetrabenzoporphyrin dendrimer H2TBP-Nw1OH (2) with 36 peripheral carboxylates, were synthesized and characterized. The pK's of the encapsulated porphyrins (pKH2P-Glu4OH = 6.2 and pKH2TBP-Nw1OH = 6.3) were found to be strongly influenced by the dendrimers, revealing significant electrostatic shielding of the cores by the peripheral charges. The titration curves obtained by differential excitation using the mixtures of the dendrimers were shown to be identical to those determined for the dendrimers individually. Due to their peripheral carboxylates and nanometric molecular size, porphyrin dendrimers cannot penetrate through phospholipid membranes. Dendrimer 1 was captured inside phospholipid liposomes, which were suspended in a solution containing dendrimer 2. No response from 1 was detected upon pH changes in the bulk solution, while the response from 2 was predictably strong. When proton channels were created in the liposome walls, both compounds responded equally to the bulk pH changes. These results suggest that porphyrin dendrimers can be used as fluorescent pH indicators for proton gradient measurements.},
  author       = {Finikova, Olga and Galkin, Alexander and Rozhkov, Vladimir and Cordero, Maria and Hägerhäll, Cecilia and Vinogradov, Sergei},
  issn         = {1520-5126},
  language     = {eng},
  number       = {16},
  pages        = {4882--4893},
  publisher    = {The American Chemical Society},
  series       = {Journal of the American Chemical Society},
  title        = {Porphyrin and Tetrabenzoporphyrin Dendrimers: Tunable Membrane-Impermeable Fluorescent pH Nanosensors},
  url          = {http://dx.doi.org/10.1021/ja0341687},
  volume       = {125},
  year         = {2003},
}