Lignin-assisted construction of sub-10 nm supramolecular self-assembly for photothermal immunotherapy and potentiating anti-PD-1 therapy against primary and distant breast tumors

Photothermal therapy(PTT)has brought hope for cancer treatments,with hyperthermia-induced immunogenic cell death(ICD),which is a critical part of therapeutically induced antitumor immune responses.Limited immune stimulation response in PTT is the primary reason for incomplete tumor ablation,therefore demonstrating urgent requirements for ICD amplifier.Herein,a sub-10 nm supramolecular nanoassembly was formed by co-assembly of clinically approved aluminum adjuvant and commonly used indocyanine green(ICG)under the assistance of lignosulfonate(LS,a green and sustainable multifunctional lignin derivative)for localized photothermal-immunotherapy of breast cancer.The overall results revealed that LS-Al-ICG is capable of inducing amplified ICD,efficiently eliciting solid immune responses through dendritic cells(DCs)activation and cytotoxic T-cell responses initiation for tumor killing.Moreover,anti-PD-1 therapy blocked the PD-1 pathway and led to remarkable anti-tumor efficacy against laser-irradiated primary tumors and distant tumors by potentiating systemic tumor specific T cell immunity.The results of this study demonstrate a handy and extensible approach for engineering green natural lignin nanoparticles for cancer immunotherapy,which shows promise for delivering other therapeutics in biomedical applications.