Features | Partner Sites | Information | LinkXpress
Sign In
Samsung
Schiller
Ampronix

“Fastener” Molecules Enhance MRI Contrast Agents

By Medimaging International staff writers
Posted on 04 Jun 2014
Image: Dr. Kong and others demonstrated that their fastener molecule readily inserted itself into the membrane of pre-made liposomes. Gadolinium stably associated with the modified nanoparticles in solution, and experiments in animal models showed that these nanoparticles produced clear diagnostic images (Photo courtesy of Janet Sinn-Hanlon, DesignGroup@VetMed, University of Illinois).
Image: Dr. Kong and others demonstrated that their fastener molecule readily inserted itself into the membrane of pre-made liposomes. Gadolinium stably associated with the modified nanoparticles in solution, and experiments in animal models showed that these nanoparticles produced clear diagnostic images (Photo courtesy of Janet Sinn-Hanlon, DesignGroup@VetMed, University of Illinois).
Biomedical scientists have increased the effectiveness of specific contrast agents that are frequently used for imaging blood vessels and internal bleeding by linking them with nanoparticles. The contrast agent being used is packaged inside or bonded to the surface of microscopic particles, which can be designed to target specific parts of the body or prolong the agent’s activity.

When associate professor of chemical and biomolecular engineering Dr. Hyunjoon Kong, graduate student Cartney Smith, and colleagues from the Institute for Genomic Biology, University of Illinois at Urbana-Champaign (USA) set out to improve magnetic resonance imaging (MRI) technology, they turned to current contrast agent technology inside out.

When clinicians perform an MRI scan, they administer a contrast agent: a compound that, when injected into the bloodstream or ingested by the patient just before the MRI, improves structure or organ clarity in the resulting image. One typical class of contrast agent, frequently used for imaging of blood vessels and internal bleeding, contains gadolinium, a rare-earth metal.

Recently, biomedical researchers have discovered ways to increase the effectiveness of certain contrast agents by associating them with nanoparticles. The contrast agent being used is packaged inside or bonded to the surface of microscopic particles, which can be designed to target certain regions of the body or prolong the agent’s activity. They are now examining the multipurpose use of nanoparticles. If particles could be loaded with several types of contrast agents or dyes instead of one, or a contrast agent along with another type of diagnostic aid or a medication, clinicians could more effectively test for and treat disorders, and limit the number of injections received by patients.

Similar to children sharing a new plaything, although, compounds packed together into a nanoparticle cannot always play well together. For instance, contrast agents may bind to other chemicals, reducing their effectiveness. Furthermore, when contrast agents are enclosed inside a nanoparticle, they may not work as well. Efforts to attach agents to the outer surface of nanoparticles by covalent formation are also challenging, as they can negatively affect the nanoparticle activity or the compounds that they carry.

Drs. Kong, Smith and colleagues attacked these challenges by using interactions between naturally occurring biomolecules as a guide. Many types of proteins are strongly attached to cell membranes not by covalent bonds, but by the sum of multiple weaker forces—the attraction of positive and negative charges, and the tendency of nonpolar (oil-like) compounds to seek each other and avoid water.

The group theorized that the same types of forces could be used to attach a contrast agent to the surface of a type of nanoparticle called a liposome, which resembles a little piece of cell membrane in the shape of a tiny bubble. The researchers designed a “fastener” molecule, DTPA-chitosan-g-C18, that is charged, attracting it to the liposome and binding it to the contrast agent gadolinium. A nonpolar region anchors it to the liposome membrane.

In a series of experiments reported October 2014 American Cancer Society’s journal ACS Nano article, Dr. Kong and coworkers demonstrated that their fastener molecule easily inserted itself into the membrane of pre-made liposomes. Gadolinium stably associated with the engineered nanoparticles in solution, and research in animal models revealed that these nanoparticles generated well-defined diagnostic images.

“The strategy works like Velcro on a molecular level to adhere functional units to the outer leaflet of a liposome,” said Dr. Smith, who was first author on the study. “This work represents a new material design strategy that is scalable and easily implemented. The development of improved contrast agents has the potential to directly impact patients’ lives by detecting damaged blood vessels.”

One of the difficulties of working with liposomes is their tendency to degrade inside the body. When the fastener-loaded liposomes degraded, some of the efficacy of the gadolinium was lost. In a second study published April 8, 2014, in the journal Langmuir, Drs. Kong and Smith developed a process for chemically cross-linking the components of the nanoparticle that prolonged the life of the nanoparticles in biologic environments.

Related Links:

Institute for Genomic Biology, University of Illinois at Urbana-Champaign



Supersonic Imagine
ARAB HEALTH
PHS Technologies

Channels

Radiography

view channel

Low-Dose CT Offers Cost-Effective Lung Screening

A new statistical analysis of from a US lung screening trial concluded that performing low-dose computed tomography (CT) screening can be cost-effective compared to doing no screening for lung cancer in aging smokers. “This provides evidence, given the assumptions we used, that it is cost-effective,” said Ilana Gareen,... Read more

Nuclear medicine

view channel
Image: The MRIdian MRI-guided radiation therapy system (Photo courtesy of ViewRay).

World’s First Clinical MRI-Guided Radiation Therapy System Awarded CE Marking

The world’s first magnetic resonance imaging (MRI)-guided radiation therapy system has received CE marking approval, which will allow the developer of the technology to deliver the systems throughout Europe... Read more

General/Advanced Imaging

view channel

Photoacoustic Imaging Optimizes Visualization of Cancerous Tissues Using Time Reversal Technology

Unique time-reversal technology is being used to better focus light in tissue, such as muscles and organs. Current high-resolution optical imaging technology allows researchers to see about 1-mm-deep into the body. In an effort to enhance this imaging technology, the investigators are employing photoacoustic imaging, which... Read more

Imaging IT

view channel

Imaging Data, Tools Developed for Heart Disease Research

A virtual machine is being developed to optimize reproducibility and data availability to assess and enhance analyses of magnetic resonance imaging (MRI) myocardial perfusion data. The project was described November 11, 2014, in the open access, open data journal GigaScience. The study’s researchers, from the Universidad... Read more

Industry News

view channel
Image: Blackford Analysis accelerates image comparison (Photo courtesy of Blackford Analysis).

Partnership to Integrate Image Workflow Server into Image Viewer

Intelerad Medical Systems (Montreal, Canada), a developer of medical imaging picture archiving and communication systems (PACS), radiology information systems (RIS), and workflow solutions, reported that... Read more
 

Events

01 Dec 2014 - 05 Dec 2014
11 Jan 2015 - 14 Jan 2015
Copyright © 2000-2014 Globetech Media. All rights reserved.