Thermo electron x series 2

Characterization of 23 nm uncoated gold particles in simulated gastric fluid was performed using dynamic light scattering on a Brookhaven ZetaPlus instrument (Brookhaven Instruments Corp., Holtsville NY). Simulated gastric fluid (SGF) was prepared as previously described [26 (link)]. Particle dissolution was investigated after 5 hours in simulated gastric fluid at 37°C. Particles were removed by high speed centrifugation and the supernatant was tested for gold ions using inductively coupled plasma mass spectrometry on a Thermo Electron X Series II (Thermo Scientific, West Palm Beach, FL, USA).

The Thermo Electron X Series II (Thermo Scientific, West Palm Beach, FL, USA) was used for all ICP-MS analyses, with indium as an internal standard. The LOD was 0.1 ppb, with an LOQ of 1 ppb. Procedural blanks were run in conjunction with all samples and subtracted as background. All groups (two particle dosing groups and four time points) were run with an n = 5. One vehicle-control group (water only, 24 hours), n = 5, was used to measure background gold. The gold detected in all control animals was below the level of quantitation (<1 ppb in any single tissue). The total number of animals used for bioavailability measurements was 45 (n = 5 for controls, n = 5 x 2 particle groups x 4 time points).