Abstract
Traditional post-treatment of colloidal nanoparticles (NPs) usually involves repeated centrifugation-wash-sonication processes to separate NPs from the original synthetic environment; however, such separation 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.
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Kuang, Y., Song, S., Liu, X. et al. Solvent switching and purification of colloidal nanoparticles through water/oil Interfaces within a density gradient. Nano Res. 7, 1670–1679 (2014). https://doi.org/10.1007/s12274-014-0527-7
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DOI: https://doi.org/10.1007/s12274-014-0527-7