Mesoporous SiO₂ Nanoparticles as Iron Nanocarriers to Induce Ferroptosis in Differentiated SH-SY5Y Neurons

The human central nervous system (CNS) is a highly complex, selective, and fragile environment. Under physiological conditions, the blood–brain barrier (BBB) maintains an immune-privileged state, allowing only specific biomolecules, nutrients, and cofactors to enter the CNS. However, this selectivity is compromised during neuroinflammation, where ferroptosis—a regulated, non-apoptotic cell death pathway driven by iron-dependent lipid peroxidation—plays a central role. In dopaminergic neurons of the substantia nigra pars compacta (SNpc), ferrous iron required for dopamine synthesis can react with hydrogen peroxide through the Fenton reaction, generating hydroxyl radicals and promoting mitochondrial dysfunction and oxidative damage. These processes are highly relevant to Parkinson’s disease, the second most prevalent neurodegenerative disorder, although the mechanisms underlying iron accumulation remain unclear. Understanding ferroptosis is therefore essential to elucidate the neurochemical progression of the disease.

In this work, we developed an in vitro model of progressive iron accumulation using human neuroblastoma SH-SY5Y cells differentiated into mature neurons with retinoic acid. Mesoporous SiO₂ nanoparticles synthesized using a modified Stöber method were employed as nanocarriers to deliver iron in a controlled manner. A modified MTT viability assay was implemented to avoid optical interference caused by the nanoparticles. Additionally, intracellular ferrous iron was quantified using the FerroOrange probe, and lipid peroxidation was assessed via 4-hydroxynonenal (4-HNE) detection, confirming the activation of ferroptosis. This approach enables a controlled and reproducible platform to study iron-induced neuronal vulnerability and provides insights into ferroptotic mechanisms relevant to Parkinson’s disease