Green synthesis of cadmium sulfide quantum dots coated with quercus infectoria and Heracleum persicum: cytotoxicity studies on RBCs and HFF-2 cells.

Cancer remains to be a major life-threatening illness, prompting ongoing efforts to develop innovative treatment methods. Nanotechnology presents distinct advantages by enabling targeted delivery to malignant cells while minimizing damage to surrounding healthy tissue. Quantum dots (QDs), nanoscale semiconductor particles, have emerged as promising tools for tumor imaging, diagnosis, prevention and treatment. Nonetheless, their application in biomedicine faces challenges due to cytotoxicity, which may affect normal cells and red blood cells (RBCs). To mitigate these issues, green synthesis utilizing plant extracts offers an environmentally friendly and cost-effective method to enhance biocompatibility. This study investigated the synthesis of cadmium sulfide (CdS) QDs, which were subsequently coated with ethanolic extracts from Heracleum persicum (HP) and Quercus infectoria (QI). The successful synthesis and surface modifications were verified through various techniques, including ultraviolet-visible (UV-Vis) spectroscopy, Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), and scanning electron microscopy (SEM). DLS results indicated hydrodynamic sizes of 258 nm for CdS@HP and 253 nm for CdS@QI, with zeta potential values shifting from - 22.4 mV for bare CdS to - 25.0 mV for CdS@HP and - 23.9 mV for CdS@QI, suggesting enhanced colloidal stability. Biological assessments, incorporating 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and hemolysis assays, revealed that bare CdS QDs exhibited substantial cytotoxicity and hemolytic activity. The HP-coated QDs achieved the highest cell viability and the lowest hemolysis, whereas the QI-coated QDs showed moderate protective effects but a slightly increased hemolytic response. These findings highlight the potential of plant-based coatings to improve the safety and stability of CdS QDs for future biomedical applications.