Abstract
X-Ray fluorescence computed tomography (XFCT) is an emerging biomedical imaging technique, which demands the development of new contrast agents. Ruthenium (Ru) and rhodium (Rh) have spectrally attractive Kα edge energies, qualifying them as new XFCT bio-imaging probes. Metallic Ru and Rh nanoparticles are synthesized by polyol method, in the presence of a stabilizer. The effect of several reaction parameters, including reaction temperature time, precursor and stabilizer concentration, and stabilizer molecular weight, on the size of particles, were studied. Resultant materials were characterized in detail using XRD, TEM, FT-IR, DLS-zeta potential and TGA techniques. Ru particles in the size range of 1–3 nm, and Rh particles of 6–9 nm were obtained. At physiological pH, both material systems showed agglomeration into larger assemblies ranging from 12–104 nm for Ru and 25–50 nm for Rh. Cytotoxicity of the nanoparticles (NPs) was evaluated on macrophages and ovarian cancer cells, showing minimal toxicity in doses up to 50 μg/mL. XFCT performance was evaluated on a small-animal-sized phantom model, demonstrating the possibility of quantitative evaluation of the measured dose with an expected linear response. This work provides a detailed route for the synthesis, size control and characterization of two materials systems as viable contrast agents for XFCT bio-imaging.
Highlights
X-Ray fluorescence (XRF) computed tomography (XFCT) is an emerging modality of biomedical imaging
Polyol synthesis is a promising route for the synthesis of various metallic NP systems, where the polyalcohol solvent acts as the reducing agent for the metallic ions in the solution
X-Ray fluorescence computed tomography (XFCT), as an emerging biomedical imaging technique, urges the need to develop new probes/contrast agents, with X-Ray absorption edge energies matched to the X-Ray excitation energy for optimal signal generation
Summary
X-Ray fluorescence (XRF) computed tomography (XFCT) is an emerging modality of biomedical imaging. With the laboratory XFCT setup Larsson et al reported the 3D imaging of MoO2 nanoparticles (NPs) in rodents with 200 μm spatial resolution at acceptable X-Ray radiation dose and exposure time with XFCT setup [1,2]. This extends the application of X-Ray CT imaging from structural imaging to molecular imaging Clinically used molecular imaging modalities include magnetic resonance imaging (MRI), optical fluorescence, ultrasound, positron emission tomography (PET) and single-photon emission computed tomography (SPECT) [3]. A library of NPs based on yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), and rhodium (Rh) elements has shown them as promising XFCT contrast agent platforms owing to their spectrally matching Kα edge energies to the liquid–metal–jet X-Ray source [4]
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