PMID- 12659161
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20030430
LR  - 20191106
IS  - 1474-905X (Print)
IS  - 1474-905X (Linking)
VI  - 1
IP  - 7
DP  - 2002 Jul
TI  - The aqueous environment in AOT and Triton X-100 (w/o) microemulsions probed by 
      fluorescence.
PG  - 500-6
AB  - The confined aqueous medium of Triton X-100/cyclohexane-hexanol/water 
      microemulsions was studied and compared with that of AOT/isooctane/water. The 
      microenvironment generated was assessed by following the photophysical behaviour 
      of the cationic dye, acridine orange (AO). This dye presents an acid-base 
      equilibrium in free bulk water (pKa approximately equal to 10.2) which is clearly 
      affected in Triton X-100 microemulsions where the neutral species is stabilised 
      at low omega0. The addition of water contributes to the appearance of the 
      protonated species. This, however, presents spectral features that show a less 
      polar and/or protic character of the encapsulated water even at high contents. 
      The "anomalous" microviscosity dependence on the amount of solubilised water 
      (omega0 = [H2O]/[Surf]) in Triton X-100 microemulsions obtained from steady-state 
      anisotropy data was used to discuss the existence of bulk free water within these 
      confined media, where at omega0 = 8, properties seem to change. In AOT, a complex 
      AO-AOT is detected in equilibrium with the protonated AO, at pH = 7. The 
      two-state excited-state formalism was applied to describe the transient data 
      which in the case of AOT introduces a rate constant that accounts for the water 
      quenching (kq = 0.51 +/- 0.03 x 10(8) M(-1) cm(-1)).
FAU - Andrade, Suzana M
AU  - Andrade SM
AD  - Centro de Quimica Estrutural, Complexo 1, Instituto Superior Tecnico, 1049-001 
      Lisboa Codex, Portugal.
FAU - Costa, Silvia M B
AU  - Costa SM
LA  - eng
PT  - Journal Article
PL  - England
TA  - Photochem Photobiol Sci
JT  - Photochemical & photobiological sciences : Official journal of the European 
      Photochemistry Association and the European Society for Photobiology
JID - 101124451
EDAT- 2003/03/28 05:00
MHDA- 2003/03/28 05:01
CRDT- 2003/03/28 05:00
PHST- 2003/03/28 05:00 [pubmed]
PHST- 2003/03/28 05:01 [medline]
PHST- 2003/03/28 05:00 [entrez]
AID - 10.1039/b201477g [doi]
PST - ppublish
SO  - Photochem Photobiol Sci. 2002 Jul;1(7):500-6. doi: 10.1039/b201477g.