Separating the turbidity spectra of vesicles from the absorption spectra of membrane probes and other chromophores

The recording of the absorption spectra of membrane probes and other chromophores is frequently difficult because of turbidity. While in highly scattering media such as tissues, the solution to the problem can be rather complex, in cell and vesicle suspensions it can be quite simple. In this work we aim to demonstrate that the ``blurred'' sum spectrum can be decomposed into the absorption and turbidity spectra using very well defined theoretical models rather than blind empirical procedures and intuition. Basically, the methodology consists in the fitting of a power law to an absorption – free segment of the total spectrum. The power parameter is related to the dimensions, refractive index and size polydispersity of the scattering particles. The proposed methodology was applied to a polyene sterol probe in lipid vesicles (both uni and multilamellar).