A generic self-assembly approach towards phototheranostics for NIR-II fluorescence imaging and phototherapy

Controllable self-assembly of photonic molecules for precise biomedicine is highly desirable but challenging to prepare multifunctional nano-phototheranostics. Herein, we developed a generic self-assembly approach to design nano-phototheranostics that provides NIR-II fluorescence imaging and phototherapy. We first designed and synthesized two amphiphilic photonic molecules, PEG(2000)-IR806 and BODIPY. Then, we prepared the co-self-assembled phototheranostic agents, PEG(2000)-IR806/B ODIPY nanoparticles (PIBY NPs). The morphology of the PIBY NPs is controllable by adjusting the ratio of PEG(2000)-IR806 and BODIPY during self-assembly. The NIR-II fluorescence properties and phototherapy capability of the PIBY NPs were demonstrated in vitro and in vivo . By tuning the ratio of PEG(2000)-IR806 and BODIPY, the PIBY NPs showed various morphologies (e.g. spherical nanoparticles, nanovesicles and rod-like nanoparticles). The PEG(2000)-IR806 plays two roles in the co-self-assemblies, one is second near-infrared (NIR-II, 1000-1700 nm) agent, the other is the surfactant for BODIPY encapsulation. The phototherapeutic PIBY NPs all show bright NIRII fluorescence and effective phototherapeutic (photothermal and photodynamic) properties, which are attributed to IR806 and BODIPY, respectively. The driving force of the self-assembly can be attributed to the electrostatic interaction between NIR806 and BODIPY and their hydrophobicity. The rod-like PIBY NPs (rPIBY NPs) demonstrated a low half inhibitory concentration (IC50) of 3.96 mu g/mL on U87MG cells. The NIR-II imaging showed the accumulation of rPIBY NPs in the tumor region. After systemic injection of rPIBY NPs at low dose (0.5 mg/kg), the tumor growth was greatly inhibited upon laser irradiation without noticeable side effects. This study provides a generic self-assembly approach to fabricate NIR-II imaging and phototherapeutic platform for cancer phototheranostics. Statement of significance Nanophototheranostics providing NIR-II fluorescence imaging and phototherapy are expected to play a critical role in modern precision medicine. Controllable self-assembly of optical molecules for the fabrication of efficient nanophototheranostics is highly desirable but challenging. This work reports for the first time the co-assembly of a NIR-II imaging contrast agent and a phototherapeutic agent to yield nanophototheranostics with various morphologies. The design of molecular co-assembly with complementary optical functions can be a generic method for future the development of phototheranostics. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study developed a generic self-assembly approach to design nano-phototheranostics with NIR-II fluorescence imaging and phototherapy. The morphology of the resulting nanoparticles can be controlled by adjusting the ratio of the components. The nanoparticles exhibit bright fluorescence and effective photothermal and photodynamic properties, showing great potential for cancer phototheranostics.