Fig. 6. Tracking SiCNP620-labeled mesenchymal stem cells in vivo. (a) Photoacoustic spectrum of labeled MSCs implanted at varying cell concentrations. Labels represent injection concentrations in cells per μL. (b) Quantified photoacoustic intensity of injected SiCNP620-labeled cells at a wavelength of 770 nm. Error bars are standard deviations of 5 ROIs. (c) Photoacoustic and ultrasound overlay images of the injections. (d) Long-term tracking of the 20 000 cells per μL implant shows that cells are still visible over a period of 14 days.
