Co-Delivery of Chemo and Immune Drugs by Prussian Blue Nanocubes for Combinational Therapy and T1-T2W MR Imaging of MDA-MB-231.

Herein, we present Prussian blue nanocube (PBNC)-based nanoformulation, co-loaded with programmed death ligand 1 (PD-L1)/programmed death protein 1 (PD-1) inhibitor (JQ1) and a chemotherapeutic drug (doxorubicin), to improve triple-negative breast cancer (TNBC) cell treatment through combining immuno-, chemo-, and phototherapy. Mechanistically, the synthesized nanoformulation induces robust pyroptotic cell death (∼86%) with a low IC50 (∼15.71 μg/mL) through the CASP3/NF-κβ /IL-1β signaling pathway and remodels the immunosuppressive microenvironment by restoring extracellular and intracellular pH and ions (Na+, K+, Ca2+). Nanoformulation also exhibits higher relaxivity values (r1 ∼ 3.4353 ± 0.103 and r2 ∼ 6.0711 ± 0.378 mM-1s-1) than commercial contrast agents (MAGNEVIST, GADOVIST, PROHANCE, etc.), indicating its potency as a dual-mode contrast agent for magnetic resonance imaging (MRI). We have also validated a drug co-loading mechanism through a series of molecular dynamics simulations, followed by experimental measurements. Importantly, in vivo studies using a xenograft mouse model demonstrate significant tumor growth inhibition, with the nanoformulation + NIR irradiated group showing the most effective anti-tumor outcome with negligible hepatic, renal, and cardiac toxicities. Taken together, it may be stated that the doxorubicin/JQ1 co-loaded PBNCs might be a potential next-generation anti-TNBC theranostic agent, which combines dual-mode MRI capability and combination therapy with reduced side effects.