Fig. 6.

Multimodal detection of PBNC-labeled stem cells. Prussian blue nanocubes (PBNCs) possess optical and magnetic properties to produce both photoacoustic and magnetic resonance (MR) contrast. PBNC-labeled stem cells were suspended at a concentration of 10k cells/μl. Top row: control, no cells injected. Middle row: 2 μl injection of PBNC-labeled stem cells. Bottom row: 5 μl injection of PBNC-labeled stem cells. Photoacoustic images (A - C) were acquired at 740 nm wavelength. Muscle was placed over the cord prior to MR imaging to simulate the clinical procedure and postoperative imaging protocol. MR images were acquired using T2 (D - F) and T2* (G - I) pulse sequences. Red arrows indicate location of stem cells. Scale bar =2 mm.