CIC biomaGUNE Develops New Nanomaterials for Medical Imaging Diagnostics
Manganese-loaded carbon nanodots show great potential as MRI contrast agents and could represent the next generation of contrast media
These nanoparticles, measuring around 5 nm and developed in the laboratory led by Ikerbasque Professor Maurizio Prato, are easily eliminated from the body and exhibit excellent biocompatibility.
Contrast agents are compounds routinely administered during clinical imaging procedures to enhance the differentiation of tissues or to improve the visibility of structures and fluids within the body, thereby facilitating medical diagnosis.
A study led by researcher Lucia Cardo and Ikerbasque Professor and AXA Chair Maurizio Prato (both from CIC biomaGUNE) has confirmed that manganese-loaded carbon nanodots could become the next generation of contrast agents for magnetic resonance imaging (MRI). The findings, published in the scientific journal ACS Nano, highlight their considerable potential.
These novel spherical nanoparticles, developed in the Carbon Bionanotechnology Laboratory led by Prato, measure approximately five nanometres in diameter (a nanometre being one billionth of a metre) and are composed primarily of carbon with a small amount of manganese. “Although present in very low proportions, the manganese is firmly integrated into the nanoparticle structure, enabling us to exploit its properties to generate excellent MRI contrast. In fact, its performance is comparable to, and in some cases even better than, that of contrast agents currently in clinical use,” explains researcher Cardo.
Safer, More Effective and More Sustainable Contrast Agents
Magnetic resonance imaging commonly relies on gadolinium-based compounds as contrast agents. Gadolinium is a metal with magnetic properties that help to highlight tumours, blood vessels and damaged tissues. While these compounds have been essential in medical diagnostics for nearly four decades, their use may pose health risks for patients with kidney impairment. Furthermore, they contribute to the persistent presence of gadolinium in the environment, as they can enter wastewater systems and are difficult to remove during treatment processes.
As a result, safer and more sustainable alternatives are being sought. Among the most promising candidates are metals considered safer and more abundant, such as manganese, which is also less expensive than other heavy metals.
The aim of this study was to establish an initial platform based on manganese-doped carbon nanodots that is stable, reproducible, well tolerated and detectable using magnetic resonance imaging. “Despite the enormous potential of these materials and their many possible applications, achieving adequate stability and reproducibility remains one of the major challenges in translating them from research into real biomedical applications. Through our work, we have not only optimised the synthesis process but also, importantly, established validation strategies that enable us to obtain a truly reliable and reproducible material,” says Cardo.
“A significant innovation of this work has been our ability to detect the nanodots by MRI in their native form,” notes CIC biomaGUNE researcher Michele Cesco, first author of the paper, “without the need to attach a molecule that directs them towards a specific organ or tissue, which is normally required to promote accumulation and facilitate detection.”
Studies conducted in animal models show that the nanoparticles are effectively cleared from the body and are highly biocompatible, even following long-term investigations. Having achieved strong performance as contrast agents, with detectability in conventional MRI comparable to that of commercial contrast media, “we were able to study the behaviour of the material itself. For example, we examined its long-term behaviour in both cells and animals and observed suitable biodistribution and rapid elimination from the body, with no significant toxic effects detected in the main organs analysed,” Cardo adds.
These findings support their potential as a new generation of manganese-based contrast agents, combining efficiency, stability and safety.
Medicine is increasingly seeking versatile contrast agents that can be used across different imaging techniques, including MRI and positron emission tomography (PET), while also offering the possibility of combining diagnosis and treatment. The nanoparticles designed at CIC biomaGUNE possess fluorescent properties, opening up opportunities for their use in other detection methods and enabling different imaging modalities to be combined within a single particle.
More broadly, carbon nanodots hold significant promise for theranostic applications, which combine diagnostic and therapeutic functions within the same platform. In other words, they offer the possibility of detecting a disease while simultaneously providing a therapeutic response. The next step is to advance along this path.
“We are working to maintain the strong MRI detection capabilities while adding new functions that will allow the nanoparticles to target specific diseases, such as cancer, while remaining detectable by MRI. At the same time, we aim to incorporate therapeutic activity. In particular, we are developing light-activated therapeutic functions. We are obtaining very promising results in this direction,” the researchers conclude.
