Concentration and pH-modulated dual fluorescence in self-assembled nanoparticles of phototautomerizable biopolymeric amphiphile

Chang Keun Lim, Jangwon Seo, Sehoon Kim, Ick Chan Kwon, Cheol Hee Ahn, Soo Young Park

Research output: Contribution to journalArticlepeer-review

31 Citations (Scopus)

Abstract

A dual-emissive biopolymeric amphiphile (GC-HBO) has been prepared by densely conjugating hydrophilic glycol chitosan (GC) with a phototautomerizable hydrophobic dye (a derivative of 2-(2′-hydroxyphenyl)benzoxazole, HBO) showing excited-state intramolecular proton transfer (ESIPT). Ratiometric modulation of phototautomeric (enol-keto) dual emission, governed by the chromophoric aggregation state, was studied with a low-molecular-weight model compound (GA-HBO) and was well correlated with the nanoparticle-forming behavior of GC-HBO via amphiphilic self-assembly in water. It has been found that the promoted chromophoric aggregation at higher concentration or at basic-to-neutral pH assists the nanostructure formation to generate predominant keto emission while the enol emission is intensified at lower concentration or with decreasing pH by disintegration of self-assembled structure. The assembly-related advantageous potential of GC-HBO for probing self-concentration and surrounding pH has been demonstrated with the ratiometric determination of critical particulation concentration (0.04 kg m-3) and near-physiological pH sensitivity (pKa ∼ 5.1).

Original languageEnglish
Pages (from-to)284-289
Number of pages6
JournalDyes and Pigments
Volume90
Issue number3
DOIs
Publication statusPublished - Sep 1 2011
Externally publishedYes

Keywords

  • Biopolymeric conjugate
  • Excited-state intramolecular proton transfer (ESIPT)
  • Fluorescent nanoparticle
  • pH sensor
  • Ratiometric fluorescence sensor
  • Self-assembly

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Process Chemistry and Technology

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