PEG surface functionalization of Bi2S3 nanorods: Structural characterization, cytocompatibility, and radiosensitizing potential

Abstract Bismuth sulfide nanorods are promising for biomedical use due to their high atomic number and biocompatibility. This paper presents their surface modification through ligand exchange with polyethylene glycol (PEG) of various molecular weights to enhance dispersibility and biocompatibility in physiological media. PEGylation was confirmed, ensuring structural integrity. The optimized formulation maintained morphology, with a hydrodynamic size of 134 nm and a zeta potential of –11.3 mV. Stability and interaction in DMEM with fetal bovine serum and artificial plasma were evaluated, showing a reversible protein corona with low association constants. Cytotoxicity assays showed minimal toxicity across concentrations. The radiosensitizing effect of PEGylated nanorods was tested under three X-ray doses, revealing a dose-dependent increase in cancer cell death, with dose enhancement factors of 1.3 and 1.6 for MCF7 and A549 cells respectively, at a survival factor of 37. These findings support PEGylated Bi 2 S 3 nanorods as stable, biocompatible platforms for enhancing radiotherapy efficacy. Graphical Abstract