Observer z1 inverted fluorescence microscope

SCC7 tumor-bearing mice were developed by injecting 2 ​× ​10⁶ ​cells in 30 ​μL of saline subcutaneously into the left thigh of C3H/HeN mice. When the tumor size reached 200–250 ​mm³, 100 ​μL of the sample solution was administered via the tail vein. Whole-body biodistribution was observed at 3, 6, 12, and 24 ​h after the injection of the samples using IVIS Lumina XRMS (PerkinElmer, Inc., Waltham, MA, USA). At each time point, 30 ​μL of blood was collected from the tail vein, and the fluorescence imaging was performed by an IVIS system. At the last time point, the tumor and major organs (heart, lung, liver, spleen, and kidney) were dissected, and ex vivo fluorescence images were obtained by IVIS. IVIS imaging was performed at a wavelength of Cy5.5. The dissected tumors were fixed in 4% paraformaldehyde for 24 ​h and treated with increasing concentrations from 10% sucrose to 20% sucrose. Then, tumor tissues were frozen in optimal cutting temperature (OCT) compound and sectioned at 10 ​μm thickness. Sectioned tissues were attached to glass slides and dried. The tissues were washed several times in PBS and counterstained with 2 ​μg/mL of Hoechst 33,342 for 20 ​min at room temperature. The fluorescence from the tissue was observed in an Observer. Z1 inverted fluorescence microscope (Carl Zeiss, Jena, Germany).