Charge‐Transfer Complex Combining Reduced Cluster with Enhanced Stability for Combined Near‐Infrared II Photothermal Therapy

Abstract

In the search for materials with enhanced near‐infrared (NIR) photothermal properties and capability of providing environment‐sensitive therapy, a method that combines isolated components into one nanocomposite is developed. The technique simultaneously involves redox, charge‐transfer formation, and ionic complexation. During the polyoxophosphomolybdate (PMo) cluster mixing with biosafe chromogen 3,3’,5,5’‐tetramethylbenzidine (TMB), the reduced state (rPMo) and the oxidized TMB in the state of charge‐transfer complex (cTMB) emerge spontaneously. The two reduced and oxidized components with charges form a stable ionic complex that resists physiology, saline, broad pH, and elevated temperature. Both the rPMo and cTMB contribute to the total sustainable photothermal conversion efficiency of 48.4% in the NIR‐II region. The ionic complex exhibits biocompatibility in in vitro cell viability evaluation and is demonstrated to enter tumor cells with sustained photothermal property and complexation stability. Due to the local acidity that triggers further interaction among rPMo clusters, a distinct accumulation of the ionic complex at the tumor position is observed after caudal vein injection. Moreover, a remarkable local NIR‐II photothermal image appears. The diminishment of tumor in mice with maintained body weight demonstrates the comprehensive effect of this NIR‐II photothermal therapeutic material.

Rational Design of Polymethine Dyes with NIR‐II Emission and High Photothermal Conversion Efficiency for Multimodal‐Imaging‐Guided Photo‐Immunotherapy

“…Thanks to the long-wavelength absorption and excellent emission in NIR-II, ICRs were expected for bio-imaging in the NIR-II region. [55,16] Unfortunately, the NIR-II emissions of ICRs were suppressed entirely in water solution because of the intermolecular π-π stacking, similar to the previously reported polymethine dyes. [37,[56][57][58] Fortunately, the nano-platform not only resists the quenching of fluorescence but also improves the dispersion of the compound in the solution.…”

Organic Charge‐Transfer Complexes for Near‐Infrared‐Triggered Photothermal Materials

“…What is more, as the aggregation of ionic complexes is characterized by tumor microenvironmental responsive, the drug of the passive targeting inhibits the tumor moreover under NIR irradiation. [ 100 ]…”

“…What is more, as the aggregation of ionic complexes is characterized by tumor microenvironmental responsive, the drug of the passive targeting inhibits the tumor moreover under NIR irradiation. [100] Although PTT is an effective therapeutic mode for primary tumors, it is challenging to deal with metastatic tumors. Other modes, such as immunotherapy, chemotherapy, chemodynamic therapy, and ferrotherapy, should be integrated into therapeutic platforms combined with PTT to construct multimodal combination therapies.…”

Charge‐Transfer Polymeric Hydrogels with Self‐Healing, Injectable, Thermosensitive, Adhesive, and Antibacterial Properties for Diabetic Wound Healing

“…[ 3 ] Numerous CT complexes are formed by CT interactions and have been studied for a long time. [ 4 ] Plenty of attractive characteristics, including photothermal therapy, [ 5 ] biomedical imaging, [ 6 ] biosensing, [ 7 ] antibacteria, [ 8 ] reversible assembly, [ 9,10 ] and wound healing, [ 11 ] have been reported from the studies of CT complexes. Bulk materials containing CT complexes can inherit their characteristics.…”