Search

The distribution characteristics of nanoparticles associated with cells are crucial to many applications, including magnetic hyperthermia, drug carriers, etc. To clarify the locations when nanoparticles enter the in vivo environments is a necessity. In this work, superparamagnetic iron oxide nanoparticles modified with polyethylene glycol (PEG-SPIONs) were prepared by high temperature thermal decomposition method, and then stereotaxic injections of PEG-SPIONs into the substantia nigra of Sprague-Dawley rats were performed. The distribution of nanoparticles in rat brain was observed by inductively coupled plasma emission spectrometer (ICP-OES) and transmission electron microscopy (TEM). It was found that the iron contents were higher in the olfactory bulb, temporal lobe, prefrontal cortex and thalamus after the injection of PEG-SPIONs for 24 h and 7 days, PEG-SPIONs were mostly distributed around the axonal membrane and dendritic membrane, and a small amount were distributed near the myelin membrane and mitochondrial membrane, which can be ascribed to the nature of PEG, the hydration size and Zeta potential of PEG-SPIONs. Along with their magnetocaloric effect the PEG-SPIONs have potential to act on the ion channels on the cell membrane under an alternating current magnetic field. • The surface of SPIONs was modified with polyethylene glycol (PEG-SPIONs). • PEG-SPIONs had good biocompatibility and hydrophilicity. • The PEG-SPIONs showed good magnetocaloric effect. • PEG-SPIONs tended to be adsorbed on the cell membranes in rat brains. • PEG-SPIONs have potential to act on the cell membrane ion channels in rats. [ABSTRACT FROM AUTHOR]

Polydopamine nanoparticles are artificial melanin nanoparticles (MNPs) that show strong antioxidant activity. The effects of MNPs on the neuroprotection of mesenchymal stem cells (MSCs) against hypoxic‐ischemic injury and the underlying mechanism have not yet been revealed. In this study, an oxygen–glucose deprivation (OGD)‐injured neuron model was used to mimic neuronal hypoxic‐ischemic injury in vitro. MSCs pretreated with MNPs and then cocultured with OGD‐injured neurons were used to investigate the potential effects of MNPs on the neuroprotection of MSCs and to elucidate the underlying mechanism. After coculturing with MNPs‐pretreated MSCs, MSCs, and MNPs in a transwell coculture system, the OGD‐injured neurons were rescued by 91.24%, 79.32%, and 59.97%, respectively. Further data demonstrated that MNPs enhanced the neuroprotection against hypoxic‐ischemic injury of MSCs by scavenging reactive oxygen species and superoxide and attenuating neuronal apoptosis by deactivating caspase‐3, downregulating the expression of proapoptotic Bax proteins, and upregulating the expression of antiapoptotic Bcl‐2 proteins. These findings suggest that MNPs enhance the neuroprotective effect of MSCs against hypoxic‐ischemic injury by inhibiting apoptosis and upregulating antioxidant defense, which could provide some evidence for the potential application of combined MNPs and MSCs in the therapy for ischemic stroke. [ABSTRACT FROM AUTHOR]

Superparamagnetic iron oxide nanoparticles (SPIONs) conjugated with hyaluronic acid (HA) functional groups have potential applications as cell targeting materials. However, SPIONs incubated with high-molecular weight HA can result in severe agglomeration. In this work, we found that when modified with degraded HA (hyaluronan oligosaccharides (oHAs)), the nanoparticles were uniformly dispersed with small hydrodynamic sizes, and the oHA-modified SPIONs exerted minimal cytotoxicity. With the same functional groups as HA, the oHA-modified SPIONs may have various biomedical applications. [ABSTRACT FROM AUTHOR]