Elemental and biomolecular changes in serum as indicators of SPION action in the body: analysis using TXRF, FTIR and...

Superparamagnetic iron oxide nanoparticles (SPION) have enormous potential for the use in medical diagnostics and therapy, including theranostics and personalized medicine. However, their clinical implementation remains limited, partly due to insufficient understanding of their systemic biocompatibility, metabolism and long-term physiological impact. In this study, we investigated the molecular and elemental alterations in blood serum following SPION administration, with the goal of identifying sensitive biomarkers of nanoparticle-induced biological responses. PEGylated SPION with a 10 nm magnetite core were intravenously administered to male and female Wistar rats. Serum samples were collected at 2 h, 24 h, and 7 days post-injection. A multimodal analytical approach was employed, combining Fourier-transform infrared (FTIR) and Raman spectroscopy to assess biomolecular changes, with total reflection X-ray fluorescence (TXRF) spectroscopy for quantitative elemental profiling. Spectroscopic analysis revealed significant, time-dependent alterations in the serum biochemical landscape. FTIR data indicated a progressive decrease in the lipid-to-protein ratio, suggesting lipid remodeling. Raman spectra showed increased hemoglobin-associated signals, consistent with increase hemolysis and indicated changes in lipid saturation as well as protein secondary structure. TXRF results revealed marked reductions in serum zinc and selenium levels-key antioxidants-alongside dynamic fluctuations in copper and calcium, often exhibiting sex-dependent trends. These findings suggest that SPION metabolism triggers coordinated physiological responses involving erythrocyte damage, oxidative stress, inflammatory signaling and disruption of elemental homeostasis. The applied multimodal spectroscopic approach demonstrates strong potential for non-invasive, high-resolution monitoring of nanoparticle-induced systemic effects and supports its future utility in nanotoxicology and translational nanomedicine.