Water-soluble ≤6 nm tantalum oxide nanoparticles have been synthesized and characterized in solution using HPLC-ICP, DLS, and multinuclear NMR. Nanoparticle formulation permitted intravenous injection, in vivo imaging, and subsequent renal clearance. A clinical CT scanner provided excellent resolution following agent injection, and distribution to the arterial system was visualized. In vitro CT imaging studies indicated that at equal molar concentration of tantalum and iodine, tantalum produced greater image contrast than iodine across the diagnostic X-ray spectrum with contrast benefit increasing with peak X-ray energy.

Size-fractionated core-shell tantalum oxide nanoparticles with a well-defined particle size distribution have several key features required of clinically viable vascular imaging compounds and may be used in developing multienergy CT imaging applications.

The bromination and characterization of octaphenylsilsesquioxane is reported. The reaction is successful with a variety of methods, including microwave assisted synthesis. The analysis of the obtained product mix was carried out with a combination of high performance liquid chromatography and matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The analysis indicates that the bromination leads to multiple bromines per octaphenylsilsesquioxane molecule with a distribution dominated by statistical odds and the reaction conditions. The results showed that the bromination is not selective and does not lead to a single defined product.Abbreviations: MALDI-TOF-MS, matrix assisted laser desorption ionization time-of-flight mass spectra; POSS, polyhedral oligomeric silsesquioxane; OPS, octaphenylsilsesquioxane

High Performance Liquid Chromatography (HPLC) is an important tool for the study of PSP toxins. It provides an alternative to bioassays and gives the concentration of individual toxin isomers. The current HPLC protocol uses a post-column chemical reaction system (PCRS) to oxidize the saxitoxin ring system to form a fluorescent chromophore. This oxidation is sensitive to changes in the flow rate, temperature, pH and age of the reagents. We have previously shown that this oxidation can be accomplished using electrochemical techniques. Termed the electrochemical oxidation system (ECOS), this approach provides a simpler alternative to the traditional PCRS-based HPLC system. A detailed description of the construction and maintenance of an HPLC-ECOS system for the analysis of PSP toxins is presented. Comparisons of the mouse bioassay, HPLC-PCRS and HPLC-ECOS system are presented for three different sample matrices: toxic dinoflagellates (Alexandrium tamarense), geoduck (Panopea generosa) and scallops (Placopectin magellanicus). In all three cases, the correlation of the HPLC-ECOS system to the mouse bioassay is similar to that obtained using the HPLC-PCRS system for the analysis of PSP toxins.