The impact of the surface modification on the subcellular distribution of nanoparticles in the brain remains elusive. The nanoparticles prepared by conjugating polyethylene glycol and maleic anhydride-coated superparamagnetic iron oxide nanoparticles (Mal-SPIONs) with bovine serum albumin (BSA/Mal-SPIONs) and with Arg-Gly-Asp peptide (RGD/Mal-SPIONs) were injected into the rat substantia nigra. Observation of transmission electron microscopy (TEM) samples obtained 24 h after perfusion showed that abundant RGD/Mal-SPIONs accumulated in the myelin sheath, dendrites, axon terminals and mitochondria, and on cell membranes in the brain tissue near the injection site. For rats injected with BSA/Mal-SPIONs, a few nanoparticles accumulated in the myelin sheath, axon terminals, endoplasmic reticulum, mitochondria, Golgi, and lysosomes of neurons and glial cells while least SPIONs in rats injected with Mal-SPIONs were found. TEM pictures showed some Mal-SPIONs were expelled out of the brain. RGD/Mal-SPIONs diffused extensively to the thalamus, frontal cortex, temporal lobe, olfactory bulb, and brain stem after injection. Only a few BSA/Mal-SPIONs diffused to the afore-mentioned brain areas. This work reveals different surface modifications on the iron oxide nanoparticles play crucial roles in their distribution and diffusion in the rat brains.
Keywords: BSA; RGD; SPIONs; distribution; rat brain.
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