Control Over Kinetic Self‐Assembly of Phthalocyanine into Photothermal Nano‐Vaccine Enabling Tunable Superlarge Absorption Redshift

Tailoring the solvent polarity allows for the manipulation of kinetic pathways, leading to a variety of self-assembled structures exhibiting distinct αZnPc macrocycle stacking modes that attribute to their different absorption redshift properties. The control over superlarge absorption redshift (ranging from 105 nm to 150 nm) of mono-α-substituted carboxy zinc phthalocyanine (αZnPc) through kinetic assembly methodologies is demonstrated.

Abstract

Supramolecular near-infrared (NIR) nanomaterials show great application prospects in cancer photothermal immunotherapy. However, the direct self-assembly of photothermal nanomaterials absorbed in biological transparent window and control over their absorption properties through aggregation behavior remains a grand challenge. Here, the control over superlarge absorption redshift (ranging from 105 nm to 150 nm) of mono-α-substituted carboxy zinc phthalocyanine (αZnPc) through kinetic assembly methodologies is demonstrated, resulting in the fabrication of photothermal nanoagents within tissue-transparent NIR window. Tailoring the solvent polarity allows for the manipulation of kinetic pathways, leading to a variety of self-assembled structures exhibiting distinct αZnPc macrocycle stacking modes that attribute to their different absorption redshift properties. Mechanistic studies of the relationship between solvent polarity and pathway complexity revealed the energy landscape that governs the unique kinetic behavior. The specific stacking mode and conformation conforming to the charge-transfer model within these αZnPc assembled structures have been revealed by theoretical calculations. Crucially, the αZnPc nanostructures show remarkable physiological stability and robust photothermal performances within biological transparent window, efficiently ablating primary tumors and triggering immunogenic cell death. This effect is further augmented by the immunomodulatory effects of thymopentin, exhibiting vaccine-like capabilities in suppressing the growth of distant tumors. This research demonstrates unprecedented levels of control over supramolecular structures and their superlarge red-shifted absorption, providing great opportunities for future design and construction of supramolecular NIR materials with fascinating properties toward cancer treatments.