Water soluble bis(indolenine)squaraine salts for use as fluorescent protein-sensitive probes

D. Lynch, M.Z.H. Chowdhury, N-L Luu, E.S. Wane, J. Heptinstall, Martin Cox

Research output: Contribution to journalArticle

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Abstract

In this study we have shown that water soluble fluorescent squaraine dyes can be produced as organic salts in combination with a range of organic cations although some cations, it was found, limit solubility. Chemical analysis of twenty-four such squaraine salts showed that only one existed in the solid-state as the pure organic salt, all others existed as hydrates with varying amounts of crystalline water, except for one that existed as a butanol solvate. Five of the twenty-four (primarily nitro-substituted cations) existed as mono-cation/sulfonic acid salts, as opposed to the bis-cationic salt state that was expected for all. Preliminary fluorescence results indicated that the increase in fluorescence verses increase of protein (bovine serum albumin) concentration was significantly hindered if the protein was stored in a phosphate buffer. Comparative experiments undertaken with the protein dissolved in water showed substantial differences in the rate of increase of fluorescence with increasing protein concentration. The largest rate of change came from the morpholinium salt. It is suggested that this is because morpholine hinders neither the hydrophobic docking of the squaraine group into the protein nor the fluorescence generation within the squaraine molecule.
Original languageEnglish
Pages (from-to)116-124
JournalDyes and Pigments
Volume96
Issue number1
DOIs
Publication statusPublished - 2013

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Salts
Proteins
Cations
Water
Positive ions
Fluorescence
Butanols
Sulfonic Acids
Bovine Serum Albumin
Hydrates
Butenes
squaraine
Buffers
Phosphates
Coloring Agents
Dyes
Solubility
Crystalline materials
Molecules
Acids

Bibliographical note

The full text of this item is not available from the repository.

Keywords

  • bovine serum albumin
  • cation exchange
  • fluorescence
  • organic salts
  • protein detection
  • squaraine dyes

Cite this

Lynch, D., Chowdhury, M. Z. H., Luu, N-L., Wane, E. S., Heptinstall, J., & Cox, M. (2013). Water soluble bis(indolenine)squaraine salts for use as fluorescent protein-sensitive probes. Dyes and Pigments, 96(1), 116-124. https://doi.org/10.1016/j.dyepig.2012.07.015

Water soluble bis(indolenine)squaraine salts for use as fluorescent protein-sensitive probes. / Lynch, D.; Chowdhury, M.Z.H.; Luu, N-L; Wane, E.S.; Heptinstall, J.; Cox, Martin.

In: Dyes and Pigments, Vol. 96, No. 1, 2013, p. 116-124.

Research output: Contribution to journalArticle

Lynch, D, Chowdhury, MZH, Luu, N-L, Wane, ES, Heptinstall, J & Cox, M 2013, 'Water soluble bis(indolenine)squaraine salts for use as fluorescent protein-sensitive probes' Dyes and Pigments, vol. 96, no. 1, pp. 116-124. https://doi.org/10.1016/j.dyepig.2012.07.015
Lynch, D. ; Chowdhury, M.Z.H. ; Luu, N-L ; Wane, E.S. ; Heptinstall, J. ; Cox, Martin. / Water soluble bis(indolenine)squaraine salts for use as fluorescent protein-sensitive probes. In: Dyes and Pigments. 2013 ; Vol. 96, No. 1. pp. 116-124.
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AB - In this study we have shown that water soluble fluorescent squaraine dyes can be produced as organic salts in combination with a range of organic cations although some cations, it was found, limit solubility. Chemical analysis of twenty-four such squaraine salts showed that only one existed in the solid-state as the pure organic salt, all others existed as hydrates with varying amounts of crystalline water, except for one that existed as a butanol solvate. Five of the twenty-four (primarily nitro-substituted cations) existed as mono-cation/sulfonic acid salts, as opposed to the bis-cationic salt state that was expected for all. Preliminary fluorescence results indicated that the increase in fluorescence verses increase of protein (bovine serum albumin) concentration was significantly hindered if the protein was stored in a phosphate buffer. Comparative experiments undertaken with the protein dissolved in water showed substantial differences in the rate of increase of fluorescence with increasing protein concentration. The largest rate of change came from the morpholinium salt. It is suggested that this is because morpholine hinders neither the hydrophobic docking of the squaraine group into the protein nor the fluorescence generation within the squaraine molecule.

KW - bovine serum albumin

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