An international team of scientists announced on July 9 a new approach for analyzing drug delivery nanoparticles, enabling more detailed understanding of their size, shape, and internal structure. The researchers successfully combined asymmetric-flow field-flow fractionation (AF4) with small-angle neutron scattering (SANS) during an experiment performed on the Institut Laue-Langevin’s D11 instrument.
This is the first time AF4 has been coupled with SANS, allowing measurement not only of nanoparticle dimensions but also the arrangement of particles and drug molecules within them. The technique could help support development of safer and more effective treatments by providing unprecedented insight into how these nanoparticles are built.
Nanoparticles are increasingly used in modern medicine to deliver drugs directly to specific organs or cell types. Their efficiency depends on characteristics such as internal and external structure and uniformity in particle size. International quality standards require that nanoparticle sizes do not vary by more than 30 percent for safe application, making close monitoring essential throughout manufacturing.
Manufacturers commonly use AF4 to monitor nanoparticle size distribution by separating particles so that smaller ones move faster than larger ones. However, previous studies had only coupled AF4 with methods like ultraviolet light absorbance or small-angle X-ray scattering (SAXS). The newly demonstrated AF4-SANS combination allows researchers to probe nanoscale organization in greater detail.
Prof. Dr. Albena Lederer from the Leibniz Institute for Polymer Research Dresden said, "In the Polymer Separation Group at Leibniz Institute of Polymer Research Dresden, we have pioneered the coupling of advanced field-flow fractionation techniques with powerful scattering methods, including AF4-SANS and thermal FFF-SAXS. These multidetection approaches allow us to extract complementary, orthogonal information from very small amounts of sample, which is particularly valuable in biomedical research. Looking ahead, we believe that such integrated analytical strategies will be decisive for understanding complex polymer systems and for guiding the design of next-generation polymer-based biomedical applications."
The team also introduced improvements to compensate for dilution effects during AF4 experiments by focusing detection exclusively on nanoparticle-rich solutions while directing solvent signals away from detectors. This allowed reliable measurements more efficiently.
The study demonstrates how coupling SANS with AF4 can enhance characterization platforms for nanoparticles used in targeted treatments—an area where precise structural information is becoming increasingly important.
