Applications of Cu²⁺-Loaded Silica Nanoparticles to Photothermal Therapy and Tumor-Specific Fluorescence Imaging

Copper-based nanomaterials have been employed as therapeutic agents for cancer therapy and diagnosis. Nevertheless, persistent challenges, such as cellular toxicity, non-uniform sizes, and low photothermal efficiency, often constrain their applications. In this study, we present Cu²⁺-loaded silica nanoparticles fabricated through the chelation of Cu²⁺ ions by silanol groups. The integration of Cu²⁺ ions into uniformly sized silica nanoparticles imparts a photothermal therapy effect. Additionally, the amine functionalization of the silica coating facilitates the chemical conjugation of tumor-specific fluorescence probes. These probes are strategically designed to remain in an 'off' state through the Förster resonance energy transfer mechanism until exposed to cysteine enzymes in cancer cells, inducing the recovery of their fluorescence. Consequently, our Cu²⁺-loaded silica nanoparticles demonstrate an efficient photothermal therapy effect and selectively enable cancer imaging.