This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Contrast agents are compounds routinely used in clinical analysis to enhance differentiation between tissues or to increase the visibility of structures or fluids within the body, thus facilitating medical diagnosis. A study led by researcher Lucia Cardo and Ikerbasque research professor and AXA chair Maurizio Prato (both at CIC biomaGUNE) confirms that manganese-doped carbon nanodots could be the next generation of contrast agents for magnetic resonance imaging.
The findings of the study, published in the journal ACS Nano, reflect their potential. These new spherical nanoparticles, developed in the Carbon Bionanotechnology Laboratory headed by Prato, are approximately 5 nanometers in size (a nanometer is one-billionth of a meter) and composed mainly of carbon, with a small amount of manganese. "Despite being present only in small amounts, the manganese is firmly integrated into the structure of the nanoparticle, so its properties can be exploited to provide exceptional contrast in MRI.
In fact, its performance is comparable to current contrast agents, or even superior in some cases," states Cardo. Compounds containing gadolinium, a metal with magnetic properties that help highlight tumors, blood vessels or damaged tissue, are commonly used as contrast agents in MRI. Although these compounds have been essential for medical diagnosis for almost four decades, their use may pose a health risk for patients with kidney failure.
They also contribute to the persistence of gadolinium in the environment, since they can enter wastewater and are difficult to eliminate during wastewater treatment. Therefore, safer and more sustainable alternatives are being sought. Researchers are currently studying the use of metals considered safer and more abundant, such as manganese, which is also more cost-effective than other heavy metals.
The aim of this study was to develop an initial manganese-doped carbon nanodot platform that would be stable, reproducible, well tolerated and detectable using magnetic resonance imaging (MRI). "Despite the great potential of these materials and their numerous possible applications, achieving adequate stability and reproducibility remains one of the main challenges in translating them from research to real-world biomedical applications. Through our work, as well as optimizing synthesis, we have also (and importantly) established validation strategies that allow us to obtain a truly reliable and reproducible material," commented Cardo.
"An important contribution of this work was that the nanodots could be detected in their natural form using MRI," says CIC biomaGUNE researcher Michele Cesco, lead author of the paper, "without having to first add a molecule that targets them toward a specific organ or tissue, something that usually contributes to their accumulation and, hence, their detection." Studies using animal models show that the nanoparticles are efficiently eliminated from the body and are highly biocompatible, even in long-term studies. Once good contrast-agent performance had been achieved—that is, very high detectability using traditional MRI, comparable to that of commercial contrast agents—"we were able to study the behavior of the material itself. For example, we studied how the material behaved over the long term, in both cells and animals, and observed adequate biodistribution and rapid elimination from the body, without detecting any significant toxic effects on the main organs analyzed," added Cardo.
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