Advance Article. 2014 Oct 16 [Epub ahead of print] ; The fluorescence properties of the new potent antitumoral methyl 3-amino-6-(benzo[d]thiazol-2-ylamino)thieno[3,2-b]pyridine-2-carboxylate in solution and when encapsulated in several different nanoliposome formulations were investigated. The compound exhibits very reasonable fluorescence quantum yields and a solvent sensitive emission in several polar and non-polar media, despite not being fluorescent in protic solvents. Fluorescence anisotropy measurements of the compound incorporated in liposomes revealed that this thienopyridine derivative can be carried in the hydrophobic region of the lipid membrane. Liposome formulations including this antitumor compound are nanometric in size, with a diameter lower than 130 nm and generally low polydispersity, being promising for future drug delivery developments. The interaction of the compound with bovine serum albumin (BSA) and the multidrug resistance protein MDR1 was monitored by FRET, the compound acting as energy acceptor. It was observed a lower interaction with MDR1 protein than with the native form of BSA, which is an important result regarding applications of this antitumoral drug. ; Foundation for the Science and Technology (FCT, Portugal), FEDER/COMPETE and QREN for financial support to the Research Centres, CFUM [Strategic Project PEst- C/FIS/UI0607/2013 (FCOMP-01-0124-FEDER-022711) and CQ/UM [Strategic Project PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-022716)] and n-STeP Project NORTE-07-0124-FEDER-000039 supported by the Operational Regional Programme of North of Portugal (ON.2). FCT and POPH/QREN/FSE are acknowledged for the Post- Doc. grant of R.C.C. (SFRH/BPD/68344/2010).