화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.110, No.30, 15021-15028, 2006
Photokinetic analysis of PRODAN and LAURDAN in large unilamellar vesicles from multivariate frequency-domain fluorescence
This paper describes a multivariate photokinetic analysis of the membrane phase dependence of PRODAN and LAURDAN photokinetics in DMPC vesicles. Decay data, arranged in the form of Fourier transformed emission-decay matrices (FT-EDMs), were collected as a function of temperature around the gel phase transition temperature. Each matrix was partitioned into the emission spectra and decay profiles of the underlying emission components using methods based on principal components analysis. The analysis revealed that both probes typically emit at least three spectral components, which vary in intensity as the membrane undergoes gel to liquid-crystalline phase transitions: a locally excited species (lambda(max) similar to 415 nm), a charge-transfer species (lambda(max) similar to 435 nm), and a solvent relaxed species (lambda(max) similar to 490 nm). In contrast to previous reports, the most red-shifted species is not photoexcited, but evolves from the locally excited species and does not exhibit the dynamic Stokes' shifts associated with conventional solvent relaxation. The primary difference in the emission of the two probes is the prominence of the charge-transfer species in the LAURDAN emission.