Simultaneous Enhancement of the Long-Wavelength NIR-II Brightness and Photothermal Performance of Semiconducting Polymer Nanoparticles

Abstract

Theranostic agents with fluorescence in the second near-infrared (NIR-II) window, especially in its long-wavelength region, and NIR-II-excitable photothermal effect is promising but challenging in tumor diagnosis and therapy. Here, we report a simple but effective strategy to develop semiconducting polymer nanoparticles-based theranostic agents (PBQx NPs) and demonstrate their applications for long-wavelength NIR-II fluorescence imaging beyond 1400 nm and photothermal therapy (PTT) of tumors upon excitation at 1064 nm. Both experimental results and theory calculations show that the brightness and photothermal performance of PBQx NPs can be simultaneously improved by simply increasing the repeating unit number of semiconducting polymers. For example, PBQ45 NPs have 5-fold higher brightness than PBQ5 NPs and 6.7-fold higher photothermal effect (based on PCE × ε) than PBQ3 NPs, and exhibit promising applications in long-wavelength NIR-II fluorescence abdomen imaging, image-guided tumor resection, and image-guided PTT. This study demonstrates the effectiveness and importance of repeating unit numbers in regulating the theranostic performance, which has not received enough attention before.

Thiadiazoloquinoxaline derivative-based NIR-II organic molecules for NIR-II fluorescence imaging and photothermal therapy

“…8a). 58 As illustrated in Fig. 8b, five TTQ-based semiconducting polymers (PBQ x ( x = 3, 5, 8, 11, and 45, respectively)) with five different repeating unit numbers were synthesized through the Stille polymerization, and subsequently these polymers were encapsulated to construct their corresponding nanoparticles (PBQ x NPs ( x = 3, 5, 8, 11, and 45, respectively)).…”

D–A Type NIR‐II Organic Molecules: Strategies for the Enhancement Fluorescence Brightness and Applications in NIR‐II Fluorescence Imaging‐Navigated Photothermal Therapy

“…Besides, Zhou group proposed an effective strategy, increasing the repeating unit number of polymers, to synchronously enhance and improve fluorescence brightness and photothermal properties ( Figure a). [ 56 ] First, they synthesized five TTQ‐based semiconducting polymers, namely PBQ x ( x = 3, 5, 8, 11, and 45, respectively), with BDT as the donor unit through changing repeating unit number of polymers using the Stille polymerization method. Subsequently, their corresponding nanoparticles, PBQ x NPs ( x = 3, 5, 8, 11, and 45, respectively), were fabricated through encapsulating polymers PBQ x into DSPE‐mPEG2000.…”

Rational Molecular Engineering of Organic Semiconducting Nanoplatforms for Advancing NIR‐II Fluorescence Theranostics

“…This research emphasizes the significance of repet-itive constitutional unit of semiconducting conjugated skeletons for regulating the optical potencies of OSNs. [80] In consideration of the accelerated nonradiative decay by the small energy gap, NIR-II OSNs generally suffer from low QY challenge. To further overcome the low QY obstacle of NIR-II OSNs, Huang et al proposed a fluorescent amplification strategy-based OSNs for optimizing NIR-II FI and imaging-assisted cancer PTT in living subject (Figure 19).…”

“…Copyright 2020, American Chemical Society. (B) Reproduced with permission [80]. Copyright 2022, American Chemical Society.…”