Biosynthesis of gold nanoparticles using rutin, a naturally sugar-based flavonoid, as a template to develop safer and more effective MRI contrast agents.

The development of safe and multifunctional nanomaterials for cancer theranostics remains a major challenge in biomedical research. Rutin-functionalized gold nanoparticles (Ru-GNPs) were synthesized via a facile, cost-effective, and sustainable green synthetic route, in which rutin acted dually as the reducing and capping agent. The successful formation of Ru-GNPs was verified by the appearance of a distinct surface plasmon resonance (SPR) absorption band and further validated through comprehensive physicochemical characterization using transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) spectroscopy. Biological evaluation confirmed minimal toxicity toward normal NIH/3 T3 fibroblasts, while Ru-GNPs induced a pronounced concentration-dependent inhibitory effect on the growth of MCF-7 breast cancer cells. MRI studies performed at 1.5 T demonstrated concentration-dependent T1-weighted signal enhancement in phantom experiments, suggesting that Ru-GNPs may warrant further investigation as potential MRI-responsive nanomaterials. The combination of green synthesis, favorable cytocompatibility, cytotoxic activity against MCF-7 cells, and MRI signal enhancement highlights the potential of Ru-GNPs for future theranostic applications. The obtained results provide a foundation for the further development of rutin-mediated gold nanoparticles as next-generation agents for integrated cancer diagnosis and treatment.