Magnetic Resonance/Infrared Dual-Modal Imaging-Guided Synergistic Photothermal/Photodynamic Therapy Nanoplatform Based on Cu1.96S-Gd@FA for Precision Cancer Theranostics

Developing new nanoplatforms for dynamically and quantitatively visualizing drug accumulation and targeting within tumors is crucial for precision cancer theranostic. However, achieving efficient tumor therapy via synergistic photothermal/photodynamic therapy (PTT/PDT) using a single excitation light source, remains a challenge. In this work, we designed Gd-surface functionalized copper sulfide nanoparticles that were modified with folic acid (FA) (Cu1.96S-Gd@FA) to overcome the above limitations and promote PTT/PDT therapeutics. Here, Cu1.96S-Gd nanoparticles were synthesized via a coprecipitation method. All samples exhibited high longitudinal relaxivity (up to 12.9 mM-1 s-1) and strong photothermal conversion efficiency (50.6%). Furthermore, the Gd ions promoted electron-hole segregation, inducing the Cu1.96S-Gd nanoparticles to generate more reactive oxygen species (ROS) than pure Cu1.96S nanoparticles. The Cu1.96S-Gd@FA enabled the targeting of folate receptor (FR) and promoted cellular uptake, consequently enhancing oncotherapy efficacy. Compared to non-targeted Cu1.96S-Gd, a higher signal enhancement for magnetic resonance (MR) imaging in vivo by Cu1.96S-Gd@FA was recorded. Given photothermal ability, the nanoparticles also could be visualized in infrared (IR) imaging. Furthermore, the nanoparticles exhibited biodegradation behavior and achieved good drug elimination performance via renal clearance. Our strategy, integrating Cu1.96S-Gd@FA nanoparticles, MR/IR dual-modal imaging, and PTT/PDT into one nanoplatform, demonstrated great potential for anti-breast cancer therapy by effectively targeting FR overexpressed breast cancer cells.