Mice bearing orthotopic MCF10CA1a tumors were injected intravenously ( i.v . ) with targeted ( LinTT1 or RPAR ) and non - targeted DiRlabeled PS ( 80 mg / kg ) . The mice were anesthetized with 3 % isoflurane ( Forane , 99.9 % w / w , Abbvie ) blended with O2 at 1 mL / min flow , and imaged using IVIS Spectrum In Vivo Imaging System ( IVIS ; PerkinElmer , US ) at different time points ( 0 ; 1 ; 3 ; 6 ; 24 ; and 48 h postinjection ) . The parameters for in vivo imaging were as follows -exposure time : 0.5 sec ; pixel binning : medium ; F / stop : 4 ; excitation filter : 745 nm ; emission filter : 830 nm ; and stage temperature : 37 ° C . After the last imaging , the animals were sacrificed by perfusion with 10 mL PBS , the tumors and organs were excised and preserved in PFA 4 % in PBS at 4 ° C . The signal from DiR - PS in tumor was measured selecting the region of interest ( ROI ) and quantified using Living Image 4.5.2 . The area under the curve ( AUC ) in tumor was constructed from the in vivo quantification data . For the ex vivo analysis of tumors treated with LinTT1 - UTO - PS , UTO - PS and free DOX , the MCF10CA1a tumor - bearing mice were i.v injected with the PS samples at a dose of 5 mg of drug / kg . After 24h the mice were terminated , tumors extracted and the immunofluorescence microscopy was performed as described below .