Gold Nanoparticles as Contrast Agents in x-ray Imaging and Computed Tomography

Abstract

Computed tomography enables 3D anatomic imaging at a high spatial resolution, but requires delivery of an x-ray contrast agent to distinguish tissues with similar or low x-ray attenuation. Gold nanoparticles (AuNPs) have gained recent attention as an x-ray contrast agent due to exhibiting a high x-ray attenuation, nontoxicity and facile synthesis and surface functionalization for colloidal stability and targeted delivery. Potential diagnostic applications include blood pool imaging, passive targeting and active targeting, where actively targeted AuNPs could enable molecular imaging by computed tomography. This article summarizes the current state of knowledge for AuNP x-ray contrast agents within a paradigm of key structure–property–function relationships in order to provide guidance for the design of AuNP contrast agents to meet the necessary functional requirements in a particular application. Functional requirements include delivery to the site of interest (e.g., blood, tumors or microcalcifications), nontoxicity during delivery and clearance, targeting or localization at the site of interest and contrast enhancement for the site of interest compared with surrounding tissues. Design is achieved by strategically controlling structural characteristics (composition, mass concentration, size, shape and surface functionalization) for optimized properties and functional performance. Examples from the literature are used to highlight current design trade-offs that exist between the different functional requirements.

Keywords::

• computed tomography
• contrast agent
• delivery
• gold nanoparticles
• surface functionalization
• targeting
• x-ray imaging

Financial & competing interests disclosure

Funding sources: National Science Foundation (DMR-1309587), Walther Cancer Foundation; St Joseph Regional Medical Center; Indiana Clinical and Translational Sciences Institute (NIH grant RR025761); and US Army Medical Research and Material Command (W81XWH-06-1-0196) through the Peer Reviewed Medical Research Program (PR054672). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Additional information

Funding

Funding sources: National Science Foundation (DMR-1309587), Walther Cancer Foundation; St Joseph Regional Medical Center; Indiana Clinical and Translational Sciences Institute (NIH grant RR025761); and US Army Medical Research and Material Command (W81XWH-06-1-0196) through the Peer Reviewed Medical Research Program (PR054672). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.