Biocompatible and Highly Luminescent Near-Infrared CuInS₂/ZnS Quantum Dots Embedded Silica Beads for Cancer Cell Imaging

Bright and stable CuInS₂/ZnS@SiO₂ nanoparticles with near-infrared (NIR) emission were competently prepared by incorporating the as-prepared hydrophobic CuInS₂/ZnS quantum dots (QDs) directly into lipophilic silane micelles and subsequently an exterior silica shell was formed. The obtained CuInS₂/ZnS@SiO₂ nanoparticles homogeneously comprised both single-core and multicore remarkable CuInS₂/ZnS QDs, while the silica shell thickness could be controlled to within 5–10 nm and their overall size was 17–25 nm. Also, the functionalized CuInS₂/ZnS QDs encapsulated in the silica spheres, expedited their bioconjugation with holo-Transferrin (Tf) for further cancer cell imaging. The CuInS₂/ZnS@SiO₂ nanoparticles not only showed a dominant NIR band-edge luminescence at 650–720 nm with a quantum yield (QY) between 30 and 50%, without a recognized photoluminescence (PL) red shift, but also exhibited excellent PL and colloidal stability in aqueous media. Impressively, the cytotoxicity studies revealed minor suppression on cell viability under both CuInS₂/ZnS@SiO₂ and CuInS₂/ZnS@SiO₂@Tf concentrations up to 1 mg/mL. The application in live-cell imaging revealed that the potential of CuInS₂/ZnS QDs as biocompatible, robust, cadmium-free, and brilliant NIR emitters is considered promising for fluorescent labels