Photoacoustic (PA) imaging and tracking of stem cells plays an important role in the real-time assessment of cell-based therapies. Nevertheless, the limitations of conventional inorganic PA contrast agents and the narrow range of the excitation wavelength in the first near-infrared (NIR-I) window hamper the applications of PA imaging in living subjects. Herein, we report the design and synthesis of a second near-infrared (NIR-II) absorptive organic semiconducting polymer (OSP)-based nanoprobe (OSPN + ) for PA imaging and tracking of stem cells. Comparison studies in biological tissue show that NIR-II light excited PA imaging of the OSPN + has significantly higher signal-to-noise ratio than NIR-I light excited PA imaging, thereby demonstrating the superiority of the OSPN + for deep tissue imaging. With good biocompatibility, appropriate size, and optimized surface property, the OSPN + shows enhanced cellular uptake for highly efficient PA labeling of stem cells. In vivo investigations reveal significant NIR-II PA contrast enhancement of the transplanted OSPN + -labeled human mesenchymal stem cells by 40.6- and 21.7-fold in subcutaneous and brain imaging, respectively, compared with unlabeled cases. Our work demonstrates a class of OSP-based nanomaterials for NIR-II PA stem cell imaging to facilitate a better understanding and evaluation of stem cell-based therapies.
- organic semiconducting polymer
- photoacoustic imaging
- second near-infrared absorption
- stem cell
ASJC Scopus subject areas
- Materials Science(all)
- Physics and Astronomy(all)