Nano Research

Article Title

Solvent switching and purification of colloidal nanoparticles through water/oil Interfaces within a density gradient


density gradient, water/oil interface, solvent switching, purification


Traditional post-treatment of colloidal nanoparticles (NPs) usually involves repeated centrifugation–wash–sonication processes to separate NPs from the original synthetic environment; however, suchseparation processes have either high energy cost or low efficiency and tend to cause aggregation. Here we show a general and scalable colloid post-processing technique based on density gradient centrifugation through water/oil interfaces. Such a one-step technique can switch the solvent in a colloid at almost any concentration without aggregation, and meanwhile purify colloidal nanoparticles by separating them from by-products and environmental impurities. Droplet sedimentation was shown to be the mechanism of this one-step concentration/purification process, and mathematical modeling was established to quantify the accumulation and sedimentation velocities of different NPs.

Graphical Abstract


Tsinghua University Press