Nanomedicines, especially those based on nanoparticles, have the promise to revolutionise healthcare in terms of both diagnostics and therapeutics. These particles, often containing metals like iron or gold, can serve as contrast agents in medical imaging, act as nutritional supplements, and even function as carriers for drug delivery.
Due to their unique properties plus careful engineering, nanomedicines can reach and accumulate in places within the body that conventional medicines cannot, making them promising for cancer detection and treatment. However, the same characteristics that make nanomedicines valuable also present challenges in ensuring their safety and quality.
Researchers have recently developed a breakthrough method to separately quantify ions, nanoparticles, and aggregates of the same metal in nanomedicines—an issue current global regulations overlook. Published in the journal Talanta, this tool sets a new standard for nanomedicine regulation.
The researchers combined two existing tools (AF4 + ICP-MS) in a novel way to pinpoint exactly what’s inside nanomedicines—making this a must-cover for anyone reporting on health, science, or tech safety.
Why it matters:
- ⚠️ Current safety guidelines treat all forms of a metal as equal—missing toxicity risks.
- 💊 Ensures safer cancer drugs and contrast agents.
- 🌿 Can also be applied to food, cosmetics, and environmental testing.
With this study, the researchers combined two existing technologies—asymmetric flow field-flow fractionation (AF4) and inductively coupled plasma mass spectrometry (ICP-MS). They used the AF4 method in a novel way, taking advantage of its initial ‘focus step.’ During this step, particles are held inside the AF4 channel by two opposing flows.
Using a special permeable membrane, cross-flows filter out the tiniest dissolved particles (ions), enabling quantification based on the differences in ICP-MS signals between samples with and without ion removal−namely, with and without the focus step. Once the ions are separated, the system then uses AF4’s standard separation process to sort the retained nanoparticles by size. Finally, the ICP-MS device attached to the output can determine the approximate number of nanoparticles of each size.
This combination enabled the team to distinguish between free metal ions, small hydroxide colloids, and nanoparticles of various sizes, all containing the same metal element.
The scientists tested their approach on Resovist, a nanomedicine used as a contrast agent in liver magnetic resonance imaging scans. The analysis revealed that only 0.022% of the iron in Resovist was present in ionic form. At approximately 6.3 micrograms per milliliter, this negligible amount falls well below levels of concern.
Additionally, the team confirmed that the active nanoparticles were smaller than 30 nanometers in diameter, with some aggregates around 50 nanometers. Importantly, no large aggregates were detected, which could reduce the effectiveness of the contrast agent. These results confirm both the safety and stability of Resovist® as a nanomedicine.
The proposed technique is particularly relevant for emerging cancer treatments that use gold nanoparticles as drug delivery systems or metallic particles for photothermal therapy.
These advanced treatments rely on the ‘enhanced permeability and retention (EPR) effect,’ by which nanoparticles leak from blood vessels around tumours and accumulate in cancerous tissue.
Additionally, this novel analytical approach extends beyond pharmaceuticals. It can also assess the safety of metal nanoparticles in food additives, cosmetics, and environmental samples—helping to ensure public health across multiple sectors. The researchers showcased its versatility by successfully analyzing both negatively charged ions (silicon) and positively charged ions (iron), indicating its potential for a wide range of nanomaterials.
Overall, by offering a more comprehensive assessment of the composition, quality, and stability of nanoparticles, this research paves the way for safer and more effective nanomedicines and nanoparticle-based technologies.
The research is titled “Evaluation of elemental impurities and particle size distribution in nanomedicine using asymmetric flow field-flow fractionation hyphenated to inductively coupled plasma mass spectrometry.”
