Sustainable synthesis of highly stable bismuth nanoparticles using rheum ribes extract for enhanced cancer imaging and photothermal ablation

Bismuth nanoparticles (BiNPs) hold significant promise for targeted cancer therapy, owing to their high atomic nucleus density. This unique property enhances their effectiveness in photothermal therapy (PTT) and computed tomography (CT) imaging, facilitating both therapeutic and diagnostic uses. Conventional approaches for synthesis and surface modification of pure BiNPs for biomedical applications are challenging. Synthesis is essential for BiNP stabilization and functionalization. This study examined Rheum ribes root extract as an eco-friendly agent for the reduction and stabilization of BiNPs using a sonochemically-assisted green technique. The physicochemical characteristics of the resulting nanoparticles were investigated. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analyses have confirmed the high crystallinity of the BiNPs. Field emission scanning electron microscopy (FESEM) and TEM images showed spherical, uniformly dispersed BiNPs, exhibiting particle diameters measuring 13.5 nm. The dynamic light scattering (DLS) test indicated that the NPs were stable as colloidal particles, with a zeta potential of -40.1 mV. Energy-dispersive X-ray analysis (EDX) validated elemental compositions, whereas fourier transform infrared (FTIR) detected bioactive functional groups on BiNPs. Raman spectroscopy further declares the composition and phase structure of the NPs. The cytotoxicity, in vitro PTT, and cellular uptake of the NPs on MDA-MB-231 cells and their effect on cancer cell apoptosis were assessed using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, near-infrared (NIR) laser illumination, and DAPI (4′,6-diamidino-2-phenylindole) fluorescence assay, respectively. The sensitivity and attenuation characteristics of BiNPs were assessed for their potential use in CT imaging using agarose gel phantoms. The NPs exhibited promising contrast agent capabilities in CT imaging. Under NIR laser irradiation, the as-synthesized NPs photothermally ablate MDA-MB-231 in vitro . Thus, BiNPs produced in this investigation are promising for CT imaging and PTT. Additional research must be conducted to examine the PTT and CT imaging of BiNPs using in vivo models.