Readily constructed squaraine J-aggregates with an 86.0 % photothermal conversion efficiency for photothermal therapy
Xin Xie, Yafang Dong, Yuan Zhang, Zongliang Xie, Xinsheng Peng, Yong Huang, Wei Yang, Bowen Li, Qiqing Zhang
Abstract
The development of photothermal agents with high photothermal conversion efficiency (PCE) and long absorption wavelengths is crucial for safe and effective anti-cancer treatment. However, achieving these advantages often requires precise molecular design and complex synthetic procedures. In this study, we present a simple, precise, and effective method for fabricating photothermal agents with high PCE using long wavelength excitation. This approach involves linking two electron-donating components, diphenylamine (DPA), and an electron-withdrawing squaraine (SQ), via a π-bridge thiophene (T). The resulting D-π-A-π-D structure leads to a red-shifted absorption band. Within the DTS structure, DPA functions as a molecular rotor, T serves as a coplanar backbone, and SQ promotes J aggregation. When DTS nanoparticles (NPs) are fabricated using an amphiphilic nano-carrier, the maximum absorption wavelength shifts from 701 to 803 nm. This shift is accompanied by reduced fluorescence and an exceptionally high PCE of 86.0 %. Both in vitro and in vivo assessments confirm that DTS NPs exhibit strong potential for photothermal antitumor therapy. Overall, this strategy offers a valuable framework for designing photothermal agents with clinical applications in mind, offering a simpler and more efficient approach to achieving high PCE and long absorption wavelengths. • Squaraine-based D-π-A-π-D type photothermal agents (DTS) were synthesized. • The fabricated DTS nanoparticles exhibited an impressive PCE of 86.0 % under an 808 nm laser. • The theoretical calculation results revealed the mechanism of its ultra-high PCE. • The DTS nanoparticles demonstrated remarkable stability and efficient antitumor performance both in vitro and in vivo.