The benefits of folic acid-modified gold nanoparticles in CT-based molecular imaging: radiation dose reduction and image contrast enhancement

Abstract

X-ray computed tomography (CT) requires an optimal compromise between image quality and patient dose. While high image quality is an important requirement in CT, the radiation dose must be kept minimal to protect the patients from ionizing radiation-associated risks. The use of probes based on gold nanoparticles (AuNPs) along with active targeting ligands for specific recognition of cancer cells may be one of the balanced solutions. Herein, we report the effect of folic acid (FA)-modified AuNP as a targeted nanoprobe on the contrast enhancement of CT images as well as its potential for patient dose reduction. For this purpose, nasopharyngeal KB cancer cells overexpressing FA receptors were incubated with AuNPs with and without FA modification and imaged in a CT scanner with the following X-ray tube parameters: peak tube voltage of 130 KVp, and tube current-time products of 60, 90, 120, 160 and 250 mAs. Moreover, in order to estimate the radiation dose to which the patient was exposed during a head CT protocol, the CT dose index (CTDI) value was measured by an X-ray electrometer by changing the tube current-time product. Raising the tube current-time product from 60 to 250 mAs significantly increased the absorbed dose from 18 mGy to 75 mGy. This increase was not associated with a significant enhancement of the image quality of the KB cells. However, an obvious increase in image brightness and CT signal intensity (quantified by Hounsfield units [HU]) were observed in cells exposed to nanoparticles without any increase in the mAs product or radiation dose. Under the same Au concentration, KB cells exposed to FA-modified AuNPs had significantly higher HU and brighter CT images than those of the cells exposed to AuNPs without FA modification. In conclusion, FA-modified AuNP can be considered as a targeted CT nanoprobe with the potential for dose reduction by keeping the required mAs product as low as possible while enhancing image contrast.

Selective heat generation in cancer cells using a combination of 808 nm laser irradiation and the folate-conjugated Fe2O3@Au nanocomplex

“…Due to their rapid division rate cancerous cells generally indicate a higher level of FA receptor expression on their surface than normal cells in order to meet this need. FA modification of AuNPs thus endows the NPs with a unique capability to particularly target cancer cells [24][25][26][27].…”

How can molecular micro-CT imaging revolutionize drug discovery?

“…Theranostic nanoparticles are generally made for concurrent diagnostic and therapeutic uses. As shown in Figure 2, an ideal theranostic nanoparticle includes three main features [1]: it contains a targeting ligand and can selectively and rapidly accumulate in diseased tissue [2]; it usually has a central imaging core capable to report biochemical and morphological characteristics of the target area [3]; it can also deliver a therapeutic material to diseased tissue [12].…”

“…It is critical to control and manage the costs per an FDAapproved drug so that the R&D output in the pharmaceutical industry can be optimized. Molecular imaging (MI) techniques are of great assistance to reduce the costs of drug discovery processes [2]. To select a compound for clinical development, its pharmacokinetic and pharmacodynamic properties must be optimized so that the best candidate can be selected.…”

“…It is also essential to precisely determine the actions of a new drug, from the molecular target to the clinical effects. In the area of drug discovery, in vivo MI techniques allow us to address two important and crucial queries [1]: how much drug gets a specific site in the body and [2] what does drug do? To answer these questions, a huge amount of money and time must be consumed if the conventional methods are applied.…”

Assessment of synergistic effect of combining hyperthermia with irradiation and calcium carbonate nanoparticles on proliferation of human breast adenocarcinoma cell line (MCF-7 cells)

“…The cytotoxicity in the treated groups against the MCF-7 cell lines was examined by the MTT assay method [17,18]. The MCF-7 cells (1 Â 10 6 cells/well) were seeded on a 96-well plate in a minimum essential medium containing fetal bovine serum.…”