Response of an environment-sensitive intramolecular charge transfer probe towards solubilization of liposome membranes by a non-ionic detergent: Association and dissociation kinetics

The present report describes an endeavor to follow the solubilization of DMPC and DMPG liposome membranes by a non-ionic detergent Triton X-100 on the lexicon of environment-sensitive intramolecular charge transfer (ICT) photophysics of an extrinsic molecular probe 5-(4-dimethylamino-phenyl)-penta-2, 4-dienoic acid methyl ester (DPDAME). The prospective applicability of the probe to function as a reporter for detergent-sequestered solubilization of liposome membranes is argued on the basis of comparison of the spectral properties of the probe in various environments. Fluorescence anisotropy study delineates the degree of motional restriction imposed on the probe in different microheterogeneous assemblies. The kinetics of association of the probe with the liposome membranes and the dissociation kinetics of TX-100-sequestered solubilization process of the liposomes have been monitored by the stopped-flow fluorescence technique and the results are rationalized in relevance to fluorescence anisotropy study.

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► Triton X-100 induced solubilization of liposome membrane is explained on the basis of the three-stage model.
► Polarity sensitive ICT emission effectively probes the vesicle to mixed micelle transition.
► Kinetics experiment reveals a slower rate of dissociation of the probe as compared to association to the liposomes.
► Fluorescence anisotropy study unveils the motional rigidity on the probe in course of vesicle to mixed micelle transition.