Graphene quantum dots functionalized with folic acid and polyethylene glycol, radiolabeled with Technetium-99m for breast cancer theranostics

This study aimed to develop and characterize a novel nanoradiopharmaceutical based on graphene quantum dots (GQDs) functionalized with folic acid (FA) and polyethylene glycol (PEG), radiolabeled with technetium-99m ( 99 ᵐTc), for potential theranostic application in breast cancer. The nanosystem showed high encapsulation efficiency of FA (78.5 %), and FTIR and AFM analyses confirmed successful functionalization and preserved nanostructure morphology. In vitro assays demonstrated selective cytotoxicity toward breast cancer cell lines (MCF-7 and MDA-MB-231), while maintaining high viability in non-tumor cells (MCF-10A). Additionally, the system reduced tumor cell adhesion to collagen and induced cytoskeletal alterations, suggesting potential anti-metastatic effects. Radiolabeling efficiency exceeded 99 % and remained stable for up to 24 h. Pharmacokinetic studies in healthy mice showed a blood half-life of 1.54 h and a profile consistent with PEGylated nanoparticles. Biodistribution revealed predominant urinary excretion, with high accumulation in the bladder and moderate uptake in liver and spleen. Biochemical parameters remained within or close to physiological ranges, indicating low acute toxicity. Overall, the GQDs-PEG-FA- 99 ᵐTc system demonstrated favorable physicochemical, biological, and radiopharmacological properties, supporting its potential as a targeted theranostic platform for breast cancer.