Incorporation of the lipid-conjugated fluorescent probe nitrobenzoxadiazole dipalmitoylphosphatidylethanolamine (NBD-PE) into bilayer lipid membranes (BLMs) provides a matrix wherein changes in the structure of the membrane can be transduced into changes in fluorescence intensity or lifetime. In the work reported here, a comparison was made between an empirical model recently developed by our group to account for alterations in the fluorescence lifetime and average fluorescence intensity of NBD-PE as a result of self-quenching and an earlier alternative model which describes self-quenching of membrane-bound chlorophyll <i>a.</i> Our model showed the more satisfactory correlation with self-quenching data obtained from lipid membranes containing 1 to 50 mol % of NBD-PE. This model was used to determine the optimum initial surface concentration of NBD-PE to be incorporated into phospholipid membranes for biosensor development. Optimization was based on the magnitude of the change in fluorescence intensity as a function of changes in the local concentration of the probe. The presence of acidic headgroups in the membrane results in negligible improvement in sensitivity, while a heterogeneous membrane structure greatly enhances the signal magnitude. Experimental results did not provide accurate optimum concentrations, although two NBD-PE surface concentrations were found to yield close agreement with theoretically predicted optimum surface concentrations of 0.027 ± 0.001 and 0.073 ± 0.001 molecules NBD-PE nm<sup>-2</sup>.
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.
Contact your librarian or system administrator
Login to access OSA Member Subscription