Fig. 7

Cooperation of quercetin (QC) and dextran-coated IONPs in memory enhancement: QCIONPs cross BBB via paracellular or intracellular pathways. After the internalization of QCIONPs to neural cells, they are trapped in the lysosome. In the acidic pH of the lysosome, QCIONPs are decomposed. Excess iron raised from IONPs metabolism can be trapped by ferritin, transferred out of the cell through ferroportin, penetrate mitochondria and the nucleus. They can induce inflammation, protein aggregation, oxidative damage, and apoptosis. The released QC from QCIONPs suppresses the causes of neuronal death caused by neurodegenerative diseases and iron ions released from IONPs core. Also, QC prevents iron overload raised from IONPs degradation via iron chelation and radical scavenging. QC, quercetin; QCIONPs, QC conjugated with iron oxide nanoparticles; BBB, blood–brain barrier. This Figure was created by BioRender (https://biorender.com/)