Spanish researchers have developed five-nanometre carbon nanodots with stable manganese. In rodent studies, the particles matched gadolinium contrast performance while showing fluorescence and good biocompatibility.
The particles measure five nanometres across. They contain a small amount of manganese and keep it locked inside their carbon structure. Rodent tests showed imaging performance comparable to gadolinium, along with fluorescence and good long-term biocompatibility.
CIC biomaGUNE led the work, which was published in ACS Nano 2026. The study tackles two problems linked to current contrast materials. Gadolinium can pose health risks for patients with impaired kidney function. Removing the metal from wastewater is also difficult.
Manganese-based MRI contrast is also entering clinical-oriented research. In 2026, the Journal of Magnetic Resonance Imaging published pharmacokinetic and pharmacodynamic work on a single oral dose of the manganese agent ACE-MBCA in adults with normal and impaired liver function.
Gadolinium has been used for around four decades. Its paramagnetic properties create a strong distinction between tissues. During an MRI examination, the metal helps make tumours and blood vessels easier to see.
Patients with reduced kidney function may eliminate gadolinium more slowly through urine. The metal can then remain in the body for longer. The risk is real.
The environmental problem is harder to ignore, too. Researchers cited in the study point to elevated gadolinium levels in wastewater near hospitals. Treatment systems have difficulty removing the metal. Continued release could affect aquatic ecosystems over the long term, according to information reported by SINC.
The new particles were built to keep manganese inside their carbon structure. That stability is central to the design. The metal stays attached to the nanoparticle during its contrast function. The organism can then eliminate the particle instead of allowing free manganese to travel through the body.
The main unresolved safety issue for manganese platforms is not simply whether they improve MRI signal, but whether they release and transport free Mn2+ ions. A review of medical nanosystems identifies potential neurotoxicity and the need to establish a sufficiently long and predictable elimination profile before clinical adoption.
The design solves one problem but creates a demanding technical test. Manganese and iron have drawn interest as alternatives to gadolinium, even though they may produce weaker images. Researchers must place enough metal inside a nanoparticle to create a comparable signal. The material must also remain stable and biologically safe.
The wider field now treats manganese-containing materials as a separate MRI-contrast direction. It is no longer limited to one isolated experiment. That shift is visible in parallel 2026 publications on other manganese-based platforms.
Researchers Michele Cesco and Lucia Cardo said they used a reliable synthesis protocol. The method was designed to produce the same compound with consistent quality. The material contains only a low proportion of manganese, yet it keeps the metal within its structure.
In the rodent experiments, the particles accumulated at levels that MRI could detect. The body also eliminated them effectively. Those results remain limited to the animal study.
The nanodots have another possible use. They emit blue fluorescence. Researchers can use that signal to track the particles inside cells and check whether they reach particular tissues or biological components.
MRI remains the main imaging method. Fluorescence provides an extra way to follow the particles.
The study does not establish a ready-to-use clinical product. More work is needed to direct the platform toward a specific tumour or another disease. Researchers also need to test whether it can combine several imaging methods.
The team has discussed adding therapeutic functions in the longer term. Other 2026 publications on manganese-containing MRI platforms show that the field is moving beyond laboratory proof-of-concept. They do not remove the need for clinical safety and clearance data.
The findings give manganese a credible place in the search for alternatives to gadolinium. A successful rodent study is still far from medical use. The strongest result is the combination of stable metal incorporation, MRI performance, fluorescence and elimination from the organism.
The environmental benefit remains a possibility, not a completed solution. The work presents a practical route for reducing exposure to free metal while preserving diagnostic capability. For now, the nanodots are a promising research platform, not an established replacement in hospitals.
