Injectable, Thixotropic, and Multiresponsive Silk Fibroin Hydrogel for Localized and Synergistic Tumor Therapy

Combinational cancer therapy offers a promising strategy to overcome the limitations of single-drug treatment, including limited therapeutic efficacy, serious side effects, and low survival rate. Injectable silk fibroin (SF) hydrogel has emerged as an effective platform for localized treatment. Herein, hydrophilic SF (HSF) was extracted from regenerated SF and self-assembled into hydrogel within 2-6 h. The obtained HSF hydrogel showed obvious viscoelasticity, thixotropic behavior, and self-healing performance. Interestingly, this hydrogel also exhibited excellent stimuli-responsive drug release profiles when triggered by multiple factors (acidity, reactive oxygen species, glutathione, hyperthermia, and near-infrared (NIR)), suggesting that it could achieve spatially and temporally on-demand drug release in response to tumor microenvironment and extra-tumor NIR irradiation. Importantly, intratumoral injection of doxorubicin (DOX)/Cy7-loaded HSF-based hydrogel (DOX/Cy7-hydrogel) plus NIR irradiation exerted the best antitumor effect among all the treatment groups, revealing the strong synergistic effects of chemo/photothermal/photodynamic therapy. It is worth noting that this DOX/Cy7-hydrogel could almost eliminate the entire tumor masses, significantly prolonging the survival time of tumor-bearing mice over 60 days without detectable adverse effects. Collectively, our findings suggest that this injectable DOX/Cy7-hydrogel with thixotropic and multistimuli responsive properties could be developed as a promising platform for localized and synergistic treatment of cancer.