Energy dispersive X‐ray analysis of titanium dioxide nanoparticle distribution after intravenous and subcutaneous injection in mice

Abstract

In an effort to understand the disposition and toxicokinetics of nanoscale materials, we used EDS (energy dispersive X-ray spectroscopy) to detect and map the distribution of titanium dioxide (TiO2) in tissue sections from mice following either subcutaneous (s.c.) or intravenous (i.v.) injection. TiO2 nanoparticles were administered at a dose of 560 mg/kg (i.v.) or 5600 mg/kg (s.c.) to Balb/c female mice on two consecutive days. Tissues (liver, kidney, lung, heart, spleen, and brain) were examined by light microscopy, TEM (transmission electron microscopy), SEM (scanning electron microscopy), and EDS following necropsy one day after treatment. Particle agglomerates were detected by light microscopy in all tissues examined, EDS microanalysis was used to confirm that these tissues contained elemental titanium and oxygen. The TEM micrographs and EDS spectra of the aggregates were compared with in vitro measurements of TiO2 nanoparticle injection solution (i.e., in water). The nanoparticles were also characterized using dynamic light scattering in water, 10 mM NaCl, and phosphate buffered saline (PBS). In low ionic strength solvents (water and 10 mM NaCl), the TiO2 particles had average hydrodynamic diameters ranging from 114-122 nm. In PBS, however, the average diameter increases to 1-2 microm, likely due to aggregation analogous to that observed in tissue by TEM and EDS. This investigation demonstrates the suitability of energy dispersive X-ray spectroscopy (EDS) for detection of nanoparticle aggregates in tissues and shows that disposition of TiO2 nanoparticles depends on the route of administration (i.v. or s.c.).

The potential health risk of titania nanoparticles

“…When TNPs were injected subcutaneously, NPs were found in liver, lymph nodes, and spleen. In contrast, when TNPs were injected intravenously, they were found in lung and kidney [31].…”

“…High ionic strength reduces the thickness of the electric double layer surrounding the charged NPs and shields the electrostatic repulsion between NPs, resulting in aggregation. In the absence of special modifications, TNPs would be expected to aggregate in body fluids, according to dynamic light scattering results [31]. For example, the average diameter of Degussa P25 measured by dynamic light scattering was 542 nm in de-ionized water and 3500 nm in DMEM, while its primary size was approximatly 26 nm [110].…”

“…Toxicokinetics of TNPs at a higher dose was studied in Balb/c female mice treated (iv) with 560 mg/kg TNP. TNP microparticle aggregates were found in lung, liver, lymph node, spleen, and kidney [31]. In an investigation of the acute toxicity and biodistribution of fine and ultrafine TiO 2 at a larger dose (5 g/kg BW by oral gavage), TNPs were transported to other organs and tissues via the gastrointestinal tract and induced hepatic injury and myocardial damage within 2 weeks [32].…”

Analysis of engineered nanomaterials in complex matrices (environment and biota): General considerations and conceptual case studies

“…Electron microscopy is presently the predominant technique to investigate the presence, aggregation state, location, and composition of ENPs in ecotoxicological tests and on/in organisms [68][69][70] (see case study II and also Dudkiewicz et al [71], which gives a comprehensive overview of EM techniques for ENP analysis in food matrices). Both the high-resolution TEM and the field emission gun-equipped SEM or scanning transmission electron microscopy systems provide the necessary spatial resolution to visualize particles down to a few nanometers in diameter.…”

Inductively Coupled Plasma‐Mass Spectrometry in Biodistribution Studies of (Engineered) Nanoparticles

“…The study by Patri et al (81) used EDX to detect and map the distribution of titanium dioxide (TiO 2 ). TiO 2 NPs were administered to mice by intravenous injection or subcutaneous injection.…”