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Metal-based nanoparticle interactions with the nervous system: The challenge of brain entry and the risk of retention in the organism
Citation:
Yokel, R., E. Grulke, AND R. MacPhail. Metal-based nanoparticle interactions with the nervous system: The challenge of brain entry and the risk of retention in the organism. WIREs Nanomedicine and Nanobiotechnology. Wiley InterScience, Silver Spring, MD, 5(4):346-373, (2013).
Impact/Purpose:
There is growing concern over the health effects of exposure to nanoparticles. Remarkably little is known about their penetration and effects on the nervous system. This invited article describes the nervous system, and the properties of the partides that may allow penetration into the central nervous system. Evidence of nanoparticle penetration of the nervous system is slim; at the very least, remarkably little has been shown to get into the brain. This article also highlights the growing evidence of long-term retention in the exposed organism following exposure.
Description:
This review of metal and metal-oxide based nanoparticles focuses on factors that influence their distribution into the nervous system, evidence that they enter brain parenchyma, and nervous system responses. Emphasis is placed on gold as a model metal-based nanoparticle and for risk assessment in the companion review. The anatomy and physiology of the nervous system, basics of colloid chemistry, and environmental factors that influence what cells see are reviewed to provide background on the biological, physical-chemical, and milieu factors that influence nervous system nanoparticle uptake. The results of literature searches reveal little nanoparticle research has included the nervous system, which about equally involved in vitro and in vivo methods, and very few human studies. The routes of uptake into the nervous system and mechanisms of nanoparticle uptake y cells are presented, with examples. Brain nanoparticle uptake inversely correlates with size. The influence of shape has not been reported. Surface charge has not been cIearIy shown to affect flux across the blood- brain barrier. There is very little evidence for distribution into brain parenchyma. Metal- based nanoparticle disruption of the blooJ-brain barrier and adverse brain changes have been shown, more pronounced by spheres than rods. Studies concentrations need to be put in exposure contexts. Wok with dorsal root ganglion cells and brain cells in vitro show the potential for metal-based nanoparticles to produce toxicity. The results should be put in the perspective of the ability of nanoparticles to distribute across the barriers protecting the nervous system of the intact organism. Effects of the persistence of poorly soluble metal-based nanopartides are of concern.
