Blackberry-Like Doxorubicin Loaded Hyaluronic Acid/Zinc Phthalocyanine Loaded Mesoporous Silica Nanocomposites for Long-Term Tumor Photodynamic and Chemotherapy Synergistic Therapy.

BACKGROUND

The co-loading of zinc phthalocyanine (ZnPc) and doxorubicin (DOX) on a nanocarrier for tumor photodynamic therapy (PDT)-chemotherapy (CT) synergistic therapy is an effective approach. However, significant differences in water solubility between DOX and ZnPc hinder their high drug-loading content within a unified carrier. Additionally, DOX's systemic toxicity limits its therapeutic dosage, while low ZnPc loading shortens PDT duration, collectively restricting the efficacy of PDT and related synergistic therapy. This study aims to design a long-term PDT and CT synergistic therapy strategy to significantly improve the therapeutic effect and reduce the toxic side effects.

METHODS

We encapsulated ZnPc within biodegradable mesoporous silica nanoparticles (bMSN NPs) as the core, followed by electrostatic coating with tumor-targeting, DOX-loaded hyaluronic acid nanoparticles (DOX-HA NPs) to fabricate blackberry-like nanocomposites (DOX-HA/ZnPc-bMSN). In vitro and in vivo experiments determined tumor long-term PDT and CT synergistic therapy efficacy with DOX-HA/ZnPc-bMSN.

RESULTS

These nanocomposites achieved high ZnPc loading (DLC: 10.2% ± 1.6%) and efficient tumor accumulation, enabling prolonged systemic circulation (> 96 h) and sustained dual-drug release in vivo, realizing long-term photodynamic and CT synergistic therapy. In vitro studies showed a low combination index (CI = 0.26), with reactive oxygen species (ROS) production enhanced by 1.6-fold and 1.9-fold for ZnPc and DOX. The median lethal dose (LD50) of DOX-HA/ZnPc-bMSN nanocomposites (138.95 mg/kg) was 15.12 times higher than that of free DOX. Notably, in vivo studies demonstrated a 96.0% tumor inhibition rate has been achieved using ultralow doses of drugs (DOX: 0.2 mg/kg; ZnPc: 2 mg/kg). This long-term PDT and CT synergistic therapy elevated intracellular ROS levels, which not only induced apoptosis in tumor cells but also activated caspase-1, leading to direct GSDMD cleavage, GSDMD-N release, and pyroptotic tumor cell death.

CONCLUSION

These nanocomposites dually trigger tumor cell apoptosis/pyroptosis, demonstrating potent therapeutic efficacy and safety for clinical translation.