Gold Nanoparticles as X-Ray, CT, and Multimodal Imaging Contrast Agents: Formulation, Targeting, and Methodology

Matthew M Mahan,Amber L Doiron

doi:10.1155/2018/5837276

Abstract

Computed tomography (CT) is among the most popular medical imaging modalities due to its high resolution images, fast scan time, low cost, and compatibility with all patients. CT scans of soft tissues require the localization of imaging contrast agents (CA) to create contrast, revealing anatomic information. Gold nanoparticles (AuNP) have attracted interest recently for their use as CT CA due to their high X-ray attenuation, simple surface chemistry, and biocompatibility. Targeting molecules may be attached to the particles to allow for the targeting of specific cell types and disease states. AuNP can also be readily designed to incorporate other imaging contrast agents such as rare earth metals and dyes. This review summarizes the current state-of-the-art knowledge in the field of AuNP used as X-ray and multimodal contrast agents. Primary research is analyzed through the lens of structure-property-function to best explain the design of a particle for a given application. Design specification of particles includes size, shape, surface functionalization, composition, circulation time, and component synergy. Key considerations include delivery of a CA payload to the site of interest, nontoxicity of particle components, and contrast enhancement compared to the surrounding tissue. Examples from literature are included to illustrate the strategies used to address design considerations.

Highlights

Medical imaging is a critical component in the diagnosis and treatment of disease
X-ray imaging was the first modern imaging technique, but rapid advancement of technology has led to the development of other clinically employed methods including ultrasound (US) [1], magnetic resonance (MR) imaging [2], computed tomography (CT) [3], positron emission tomography (PET) [4], PET/CT [5], and PET-MRI [6]
After injection of the iodine, an attenuation of 25 Hounsfield units (HU) was observed in the vasculature, which allowed for the differentiation of vasculature from tumor tissue [106]

Summary

Introduction

Medical imaging is a critical component in the diagnosis and treatment of disease. X-ray imaging was the first modern imaging technique, but rapid advancement of technology has led to the development of other clinically employed methods including ultrasound (US) [1], magnetic resonance (MR) imaging [2], computed tomography (CT) [3], positron emission tomography (PET) [4], PET/CT [5], and PET-MRI [6]. Gold nanoparticles have been employed as optical biosensors [11], drug delivery vehicles [12], and imaging contrast agents [13] and laser-based treatments [14]. Their simple formulation and reactive surface allow for a variety of molecules including drugs, targeting peptides or proteins, contrast agents, or other moieties to be attached. Recent reviews of therapeutic uses of AuNP are available elsewhere [24,25,26,27]

Gold Nanoparticles in X-Ray Imaging

Multimodal Particles

Nuclear Imaging

Conclusion