Mapping technique for biodistribution of elements in a model organism, Caenorhabditis elegans, after exposure to copper nanoparticles with microbeam synchrotron radiation X-ray fluorescence

To investigate the toxicological effects of nanomaterials, experimental studies on the absorption and accumulation in organisms are of broad interest. In the present study, Caenorhabditis elegans (C. elegans) was used as a "model" organism to investigate the bioaccumulation and toxicological effects of engineered copper nanoparticles with a scanning technique of microbeam synchrotron radiation X-ray fluorescence (μ-SRXRF). The adult hermaphrodite is anatomically simple with 959 somatic cells and 1 mm in length. The mapping results of the whole organism indicate that the exposure to copper nanoparticles can result in an obvious elevation of Cu and K levels, and a change of bio-distribution of Cu in nematodes. Accumulation of Cu occurs in the head and at a location 1/3 of the way up the body from the tail compared to the un-exposed control. In contrast, a higher amount of Cu was detected in other portion of worm body, especially in its excretory cells and intestine when exposed to Cu²⁺. The results compared well with total Cu levels in nematodes, which were 4.10 ± 0.54, 12.32 ± 0.49 and 5.22 ± 0.63 μg g^-1 dry weight for the PBS, Cu²⁺ and Cu nanoparticle groups, respectively, measured by ICP-MS. The nondestructive and multi-elemental μ-SRXRF provides an important tool for mapping the elemental distribution in the whole body of a single tiny nematode at lower levels.