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Photothermal therapy operated in the second near-infrared (NIR-II, 1000–1700 nm) window and fluorescence imaging in the NIR-IIb (1500–1700 nm) region have become the most promising techniques in phototheranostics. Their combination enables simultaneous high-resolution optical imaging and deep-penetrating phototherapy, which is essential for high-performance phototheranostics. Herein, carboxyl-functionalized small organic photothermal molecules (Se-TC) and multi-layered NIR-IIb emissive rare-earth-doped nanoparticles (NaYF4:Yb,Er,Ce@NaYF4:Yb,Nd@NaYF4, RENP) were rationally designed and successfully synthesized. Then, high-performance hybrid phototheranostic nanoagents (Se-TC@RENP@F) were easily constructed through the coordination between Se-TC and RENP and followed by subsequent F127 encapsulation. The carboxyl groups of Se-TC can offer strong binding affinity towards rare-earth-doped nanoparticles, which help improving the stability of Se-TC@RENP@F. The multilayered structure of RENP largely enhance the NIR-IIb emission under 808 nm excitation. The obtained Se-TC@RENP@F exhibited high 1064 nm absorption (extinction coefficient: 24.7 L g−1 cm−1), large photothermal conversion efficiency (PCE, 36.9%), good NIR-IIb emission (peak: 1545 nm), as well as great photostability. Upon 1064 nm laser irradiation, high hyperthermia can be achieved to kill tumor cells efficiently. In addition, based on the excellent NIR-IIb emission of Se-TC@RENP@F, in vivo angiography and tumor detection can be realized. This work provides a distinguished paradigm for NIR-IIb-imaging-guided NIR-II photothermal therapy and establishes an artful strategy for high-performance phototheranostics. [ABSTRACT FROM AUTHOR]

A novel conjugated polymer (DCT) with intrinsic multifunction was designed and synthesized. High-effect phototheranostic nanoagents DCT NPs were further fabricated based on single-component DCT, which displayed large Stokes shift (363 nm), satisfying near-infrared II (NIR-II) fluorescence emission, good photothermal and photodynamic performances. Under illumination of a single 808 nm laser, high therapeutic efficiency of DCT NPs was confirmed by MTT, live-dead staining and flow cytometry assays. Besides, in vivo high quality NIR-II imaging based on DCT NPs was also demonstrated. Overall, this study provides an effective strategy for constructing of high-effect single-component phototheranostic nanoagents. [Display omitted] • The conjugated polymer DCT could be easily obtained via Stille coupling reaction. • The DCT NPs exhibited outstanding NIR-I absorption, satisfying NIR-II fluorescence emission, and large Stokes shift. • DCT NPs displayed superior biocompatibility, good water-solubility, excellent photostability. • DCT NPs could produce toxic ROS and hyperthermia for elimination of tumor cells under a single 808 laser irradiation. • In vivo vascular structure and tumor imaging was successful executed based on DCT NPs. [ABSTRACT FROM AUTHOR]