Fig. 6

In vitro PA imaging of labeled MSC^Cxcr3. a Photographs of MSC^Cxcr3 before (Pre), after (D0) and 20 days after (D20) uptake of TAT-CPNPs, respectively. b In vitro long-term PA tracking of TAT-CPNPs labeled MSC^Cxcr3. PA imaging under 1064 nm excitation were performed for tube phantoms containing PBS (lane 1), unlabeled MSC^Cxcr3 (lane 2) and TAT-CPNPs labeled MSC^Cxcr3 collected right after (D0, lane 3), 10 days (D10, lane 4) or 20 days after (D20, lane 5) incubation with TAT-CPNPs. Representative PA images and quantification analysis were shown. c Penetration performance assessment of NIR-II PA imaging for deep tissue located-labeled MSC^Cxcr3 resuspended in PBS at 2 × 10⁶ cells/mL. PA and US overlaid images showed PA signal of unlabeled or labeled MSC^Cxcr3 covered by different thickness of chicken breast tissue. PA images were acquired under 800 nm or 1064 nm laser excitation. Only the tube region of interest is shown for the PA image. Scale bar, 1.25 mm. WL, wavelength. ns, no significance, **P < 0.01, ***P < 0.001; error bars, SEM