## 3 Results and Discussion
### X-ray Photoelectron Spectroscopy (XPS) Analysis
The cell viability results are expressed as the mean of cell viability percentage \(\pm\) the standard deviation from three independent experiments. Statistical analysis was performed using two-way ANOVA followed by [PERSON]’s multiple comparison test. Significance was indicated as * \(p\) < 0.05 and ** \(p\) < 0.01. Reactive Oxygen Species (ROS) Induced by Fe\({}_{3}\)O\({}_{4}\) and Fe\({}_{3}\)O\({}_{4}\)-Ag Decorated Nanoparticles on Human Fibroblast (HFF-1) and Breast Cancer Cells (MCF-7)  
The production of ROS was measured to corroborate the biocompatibility of Fe\({}_{3}\)O\({}_{4}\) and Fe\({}_{3}\)O\({}_{4}\)-Ag decorated nanoparticles in human cells. Figure 7a,b shows the ROS measurement production induced by Fe\({}_{3}\)O\({}_{4}\) and Fe\({}_{3}\)O\({}_{4}\)-Ag decorated nanoparticles on human fibroblast (HFF-1) and breast cancer cells (MCF-7), respectively. Different concentrations of nanoparticles were tested in human fibroblast cells HFF-1 (Figure 7a). Interestingly, only higher concentrations (100 \(\upmu\)g/mL) of Fe\({}_{3}\)O\({}_{4}\)-Ag decorated nanoparticles reduced ROS production. This finding contrasts with established knowledge, which typically associates magnetite nanoparticles with inducing oxidative stress in mammalian cells [55; 56]. The same effect was observed in human breast cancer MCF-7 cells, as illustrated in Figure 7b, Fe\({}_{3}\)O\({}_{4}\)-Ag decorated nanoparticles induced a decrease in the level of ROS production only after 50 \(\upmu\)g/mL, and at higher concentrations (100 \(\upmu\)g/mL) Fe\({}_{3}\)O\({}_{4}\) also reduced the level of ROS production. To the best of our knowledge, Fe\({}_{3}\)O\({}_{4}\) nanoparticles are widely recognized for inducing oxidative stress effects in cells. However, a report indicates that Fe\({}_{3}\)O\({}_{4}\) magnetite nanoparticles demonstrate the opposite effect: they reduce metal-induced oxidative stress by decreasing malondialdehydedehyde concentration and increasing superoxide dismutase levels [56]. These findings suggest that Fe\({}_{3}\)O\({}_{4}\)-Ag decorated nanoparticles may have a more pronounced effect on modulating oxidative stress in both normal and cancer cells. While Fe\({}_{3}\)O\({}_{4}\) nanoparticles show a greater capacity to produce ROS. Previous studies have shown that the ability of nanoparticles to generate reactive oxygen species is a critical factor in determining their cytotoxicity and potential therapeutic applications; enhancing ROS production may be an effective anticancer strategy [13; 57; 58]. On the other hand, excessive production of ROS can also have detrimental effects on normal cells due to oxidative stress and the associated genotoxic effect [58]. The differential response observed between the two cell lines in this study highlights the importance of evaluating the biocompatibility of nanoparticles in cancerous and non-cancerous cells. The findings of this study contribute to the understanding of the interactions between nanoparticles and cellular redox homeostasis, which is crucial for developing safe and effective nanoparticle-based therapies. Figure 7: ROS measurement production induced by Fe\({}_{3}\)O\({}_{4}\) and Fe\({}_{3}\)O\({}_{4}\)-Ag decorated nanoparticles on (**a**) human fibroblast (HFF-1) and (**b**) breast cancer cells (MCF-7). Statistical analysis was performed using two-way ANOVA followed by [PERSON]’s multiple comparison test. Statistical significance was indicated as * \(p<0.05\) and ** \(p<0.01\) and *** \(p<0.001\). Hemocompatibility and Nitric Oxide Production Induced by Fe\({}_{3}\)O\({}_{4}\) and Fe\({}_{3}\)O\({}_{4}\)-Ag Decorated Nanoparticles  
A hemolysis assay was conducted on human red blood cells to ensure the biocompatibility of both Fe\({}_{3}\)O\({}_{4}\) and Fe\({}_{3}\)O\({}_{4}\)-Ag decorated nanoparticles. The threshold for hemocompatibility is indicated by the dotted black line at 5% of hemolysis.