Immunotoxicity of metal oxide nanoparticle: zinc oxide

Nanoparticles (NPs) are characterized by notable physico-chemical features such as size, surface charge, porosity, and shape when compared to their bulk counterparts. Recent studies on NPs have drawn tremendous attention owing to their accelerating demands and applications in diverse sectors such as industry, medicine, agriculture and energy production. However, the novel properties of nanoparticles hold uncertainty in terms of safety, specifically during interaction with the cell, DNA, protein, lipid and cellular membrane. Even though nanotechnology holds considerable promise, the novel properties of NPs may pose detriment to the biological system. While NPs interact with the immune system of host, their immunotoxicity (toxicity of the NPs to the immune system) still remain unexplored. Furthermore, NPs can pose danger to the immune system, which can be categorized as immunostimulation and/or immunosuppression. Despite this divergent category, there is no international guideline for immunotoxicity assessment of NPs. Existing parameters for toxicity evaluation are designed for toxic substances, not specific for NPs. This review will focus on the immunotoxicity of metal oxide nanoparticles in general as well as nano zinc oxide in particular, followed by the limitations of the existing parameters in gauging immunotoxicity and the new aspect of nanoimmunotoxicity based on current techniques.