Spanish researchers have developed five-nanometre carbon nanodots with stable manganese. In rodent studies, the particles matched gadolinium’s contrast performance while showing fluorescence and good biocompatibility.
The particles measure five nanometres across and contain a small amount of manganese 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 study, published in ACS Nano in 2026. It addresses two problems linked to current contrast materials: gadolinium can pose health risks for patients with impaired kidney function, and removing the metal from wastewater is difficult.
Gadolinium has been used for around four decades. Its paramagnetic properties create a strong distinction between tissues, making tumours and blood vessels easier to see during an MRI examination.
Patients with reduced kidney function may clear gadolinium more slowly in their urine, leaving the metal in the body longer. That risk is real.
The environmental problem is also hard to ignore. Researchers cited in the study point to elevated gadolinium levels in wastewater near hospitals. Treatment systems struggle to remove the metal, and continued release could affect aquatic ecosystems over the long term, information from information reported by SINC.
The new particles were designed 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 without free manganese travelling through the body.
The design addresses one problem but sets a demanding technical challenge. 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 while keeping the material stable and biologically safe.
The wider field now treats manganese-containing materials as a distinct direction in MRI contrast. The work is no longer limited to one isolated experiment; parallel 2026 publications on other manganese-based platforms reflect that shift.
Researchers Michele Cesco and Lucia Cardo said they used a reliable synthesis protocol to produce the same compound with consistent quality. The material contains only a low proportion of manganese, yet keeps the metal within its structure.
In the rodent experiments, the particles accumulated at levels detectable by MRI. 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 basic imaging method, while fluorescence offers another 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, but clinical safety and clearance data are still needed.
The findings give manganese a credible place in the search for alternatives to gadolinium. A successful rodent study remains far from medical use. The strongest result is stable metal incorporation that preserves MRI performance, with the particles also fluorescing before elimination from the organism.
The environmental benefit remains a possibility, not a completed solution. The work presents a practical route to reducing exposure to free metal while preserving diagnostic capability. For now, the nanodots remain a promising research platform, with no established replacement in hospitals.
