Organic Semiconducting Polymer Nanoparticles for Photoacoustic Labeling and Tracking of Stem Cells in the Second Near-Infrared Window

Abstract

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.

Synergistic Effects of Novel Superparamagnetic/Upconversion HA Material and Ti/Magnet Implant on Biological Performance and Long‐Term In Vivo Tracking

“…The versatility of small size micro‐ to nano‐materials is showing bright prospects in bioimaging and tracking, disease diagnosis and treatment, as well as cell therapy and tissue repair. With the development of tissue engineering and regenerative medicine, the traceable repair materials will play a more important role, such as for facilitating a better evaluation of stem cell‐based therapies, revealing the intracellular interaction,11b and expediting the healing of delayed union or nonunion bone fractures . The tracking capacity of the HYH‐Fe material will provide valuable information for future researches and applications, for example, to locate the distribution of the material in tissues, to evaluate the effect of material degradation on bone reconstruction and the quality of osteointegration.…”

Photoacoustic imaging and photothermal therapy in the second near-infrared window

“…9b) for PA imaging and tracking of stem cells. 67 The OSPN + nanoprobe had excellent stability and its PA intensity was almost invariable even after irradiation with 24 000 laser pulses (Fig. 9c).…”

“…3h) core, an anionic interlayer, and a cationic shell. 67 The SP core with the strong electron-withdrawing ability of the thiadiazoloquinoxaline unit served as the PA signal generator upon NIR-II and NIR-I light excitation and was prepared via a Pd-catalyzed Stille coupling reaction. Subsequently, water soluble nanoparticles (OSPNs À ) with a large negative surface charge were prepared by encapsulating amphiphilic poly(styrene maleic anhydride) (PSMA) in the SP core via nanoprecipitation.…”

Organic Semiconductors for Photothermal Therapy and Photoacoustic Imaging

“…In vivo studies showed that cells labeled with OSPN+ had stronger PA intensity than unlabeled cells. The NIR‐II PA contrast enhancements of transplanted human mesenchymal stem cell (hMSCs) labeled with OSPN+ in subcutaneous and brain imaging were 40.6 and 21.7 times, respectively …”

“…The NIR-II PA contraste nhancements of transplanted humanm esenchymal stem cell (hMSCs) labeled with OSPN + in subcutaneousa nd brain imaging were 40.6 and2 1.7 times, respectively. [109]…”