Silicon carbide nanoparticles as a photoacoustic and photoluminescent dual-imaging contrast agent for long-term cell tracking

Silicon carbide nanoparticles (SiCNPs) are durable, physically resilient, chemically inert, and biocompatible. Silicon carbide particles smaller than 10 nm show photoluminescence due to quantum confinement effects and have been reported in imaging different cell lines. To further explore the potential of silicon carbide nanomaterials in cell imaging, we studied the photoluminescence and photoacoustic properties of three SiCNPs of approximately 30, 80, and 620 nm. All these SiCNPs show photoluminescence and photoacoustic signals, and the 620 nm silicon carbide nanoparticles (SiCNP620) show the highest photoluminescence and photoacoustic intensity. SiCNP620 is biocompatible with a good cell labeling capacity. It could image mesenchymal stem cells in vitro for more than 20 days via photoluminescence even when the cells were differentiated into adipocytes and osteocytes. The same SiCNP620 could also produce photoacoustic signals and track stem cells in vivo for over 14 days.