Figure 13

BP-NR-based TPFI for the cartilage of mice in vivo. (a) Experimental settings for cartilage TPFI in the ear of mice. (b) The anatomic illustration of mice auricle. Intravital TPFI of BP-NR-stained cartilage in the ear of mice at 10 min postinjection via tail vein under the excitation at 810 nm. TPFI of (c) bright field, (d) red channel (emission collected at 575–630 nm for BP-NR), (e) green channel (emission collected at 495–540 nm for BP) and (f) the merged image of (c–e). Scale bar: 20 μm. The lacuna is outlined by white dotted lines and chondrocytes are indicated by green arrows. (g) Schematic illustration of a FRET-based co-assembled nanosystem as a TPFI contrast agent in vivo. The BP nanoaggregates as donors and four different dyes (that is, NR, DCM, RhB and Rh6G) as acceptors were utilized to construct the highly efficient FRET nanosystems.²⁰⁶