Monitoring drug stability by label-free fluorescence lifetime imaging: A case study on liposomal doxorubicin

In a previous report, we demonstrated that Doxorubicin (DOX) intrinsic fluorescence can be exploited in combination with the phasor approach to fluorescence lifetime imaging microscopy (FLIM) and quantitative absorption/fluorescence spectroscopy to resolve the supramolecular organization of the drug within its FDA-approved nanoformulation, Doxil®. The resulting 'synthetic identity' comprises three co-existing physical states of the drug within Doxil®: a dominating fraction of crystallized DOX (DOXc >98%), and two minor fractions of free DOX (DOXf 1/41%), and DOX associated with the liposomal membrane (DOXb [removed]