Fused-Ring Small-Molecule-Based Bathochromic Nano-agents for Tumor NIR-II Fluorescence Imaging-Guided Photothermal/Photodynamic Therapy

Abstract

Optical imaging in the second near-infrared (NIR-II) windows reduces much more autofluorescence and photon scattering from biological tissues and allows further tissue penetration depth and superior spatial resolution in living bodies. Herein, a fused-ring 2,2′-((2Z,2′Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2,″3″:4′,5']thieno-[2′,3′:4,5]pyrrolo[3,2-g]thieno[2′,3′:4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (TPBT) molecule was explored as a multifunctional tumor theranostic reagent for photothermal/photodynamic therapy guided by NIR-II imaging.The TPBT molecule has an electron-deficient core with a laddertype multi-fused ring and shows a narrow band gap that can enhance the near-infrared absorption. The J-aggregative TPBT NPs were formed by nanoprecipitation with great bathochromic shift in absorption and emission spectra, which endows them with ideal fluorescence imaging ability in the NIR-II region. Moreover, TPBT NPs present both higher photothermal conversion efficiency (∼36.5%) and effective ROS generation ability, making them excellent candidate for cancer photothermal/photodynamic therapy. Moreover, the biocompatible TPBT NPs can effectively passively target tumor sites due to their enhanced permeability and retention effect for more precision treatment. Thus, TPBT NPs as a multifunctional phototheranostic agent in the NIR-II region present promising potential in clinical cancer NIR-II imaging-guided phototherapy.

Organic conjugated small molecules with donor–acceptor structures: design and application in the phototherapy of tumors

“…In 2021, many groups, including our own, demonstrated that Y6 has good anti-tumor activities based on the combination of PDT and PTT (Table 3). [175][176][177] In addition, Tian's group systematically studied the effects of the side chains in Y-series photosensitizers on their PTT performance. 178 The flexible side chains are more facile to rotate than the rigid side chains, which have big effects on the photothermal conversion.…”

NIR‐II Organic Nanotheranostics for Precision Oncotherapy

“…Another SM TPBT was explored, and there was no NIR‐II fluorescence when dispersed in an organic solvent. [ 79 ] However, TPBT could form the J ‐aggregates by nanoprecipitation. TPBT NPs had a NIR‐II emission shoulder, which was enough for NIR‐II FLI.…”

Recent Advances of NIR-II Emissive Semiconducting Polymer Dots for In Vivo Tumor Fluorescence Imaging and Theranostics

“…When NIR-II light passes through tissues, the interaction between photons and tissues is significantly reduced, and the photons can penetrate into deeper tissues, so as to achieve better surgical guided anatomy (Figure 1b). For this purpose, various NIR-II emissive fluorescent probes, such as metal nanoparticles [16][17][18], inorganic semiconductor nanoparticles [19,20], small molecular-based nanoparticles [20,21], and aggregation-induced emission (AIE) nanoparticles [22,23], have been established. Very recently, semiconducting polymer dots (Pdots) have attracted extensive attention for in vivo fluorescence imaging applications [24].…”