Preparation and evaluation of bovine serum albumin-protected copper sulfide nanoparticles

This study aimed to prepare bovine serum albumin (BSA)-protected copper sulfide nanoparticles (CuS@BSA), systematically characterize their physicochemical properties, and preliminarily evaluate their in vitro antitumor activity, providing an experimental basis for the development of nanotherapeutics for tumor photothermal therapy. CuS@BSA was synthesized via biomineralization and characterized by dynamic light scattering (DLS), ultraviolet-visible spectrophotometry (UV-Vis), and Fourier transform infrared spectroscopy (FTIR). Stability, pH-responsiveness, and in vitro cytotoxicity were also investigated. The results showed that CuS@BSA had a uniform particle size (78 ± 5 nm, PDI = 0.262 ± 0.02), significant absorption in the near-infrared region (800 nm), and successful BSA coating. The nanoparticles exhibited good storage, serum, and dilution stability, and showed pH-sensitive aggregation at acidic pH (5.0). Methyl thiazolyl tetrazolium (MTT) assay and live/dead cell staining demonstrated that CuS@BSA had extremely low dark toxicity (> 80% cell viability at 50 µg/mL) but exerted significant photothermal killing effect on 4T1 cells upon 808 nm NIR laser irradiation (IC 50 = 50 µg/mL). In conclusion, CuS@BSA nanoparticles possess good dispersion stability, pH responsiveness, and low dark toxicity, and can effectively inhibit 4T1 cell growth through photothermal therapy, laying a foundation for subsequent antitumor research.