Charge Transfer-Mediated J-Aggregates of Azaindole Cyanine with 160 nm Absorption Redshift for Efficient NIR-II Photothermal Tumor Therapy
Tiancong Shi, Xi Chen, Xiaolong Li, Xin Li, Yang Zhao, Hongyi Zhang, Fuping Han, Lihan Cai, Xiao Zhou, Yan Su, Wen Sun, Jianjun Du, Jiangli Fan, Xiaojun Peng
Abstract
The J-aggregation of organic chromophores with ultralarge redshifts (>150 nm) represents a promising strategy for advancing photothermal therapy in the second near-infrared (NIR-II, 1000–1700 nm) window for tumor treatment. In this study, we designed and synthesized a heptamethine cyanine dye, CyN-OMe, by incorporating azaindole moieties. These moieties allowed the precise modulation of the intramolecular electronic distribution and intermolecular interactions, facilitating the rapid formation of the charge transfer-mediated J-aggregates of CyN-OMe in saline solutions. The maximum absorption wavelength of this aggregate red-shifted to 1035 nm in the NIR-II window, representing a substantial redshift of 160 nm relative to that of the monomer. We systematically explored the mechanism underlying the J-aggregate formation of CyN-OMe and evaluated its stability under varied conditions. Furthermore, the CyN-OMe J-aggregates demonstrated a high photothermal conversion efficiency of 63.7% under 1064 nm laser irradiation and successfully achieved complete tumor ablation in a mouse model. This work provides a general molecular design strategy for developing J-aggregates with ultralarge redshifts.