Nanotechnology Now - Press Release: Density gradient ultracentrifugation for colloidal nanostructures separation and investigation

Monodispersed nanoparticles and their assemblies have been demonstrated great application potentials due to their unique optical, electrical, magnetic and catalytic properties. During the last two decades, as the rapid development of nanomaterials, great progress of the synthetic methods of various monodispersed nanoparticles including semiconductors, metals and oxides have been made, and many assemblies based on single component or multicomponents have also been fabricated and demonstrated their unique functions. However, the synthetic repeatbility of monodispersed nanomaterials always remains a main limit of large-scale fabrications and applications. Further, rational design and synthesis of doped nanostructures with complicated components or complex structures such as core/shell structures, assymmetric structures, have become new issues in chemistry and material science, mainly due to the uncertain repeatibility. On the contrary, the separation methods for nanomaterial remain far behind. Typical methods such as membrane filtration, electrophoresis and magnetic field, also have many restraints and limited separation effect, which hinder the practical applications of nanodevices in various fields.

Aiming to solve the above issues, the DGUC technique, which was used to sort marcomolecules in biological field, has recently been demonstrated as an efficient way of sorting colloidal nanoparticles by several groups including Hersam's group and Sun's group. The DGUC can realize the separation of nanoparticles according to their differences in chemistry, structure, size and/or morphology. The authors introduced the classification, mechanism, applicability and instructions of DGUC, and demonstrated the applications including separation, purification and ultraconcentration of nanoparticles by DGUC, verifying the versatility. They further developed a new method "lab in a tube", which is helpful to monitor and get deeper insights of synthetic mechanism, in situ surface reactions and assembly processes.

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This work was supported by the National Natural Science Foundation of China (NSFC), the National Key Research and Development Project of China (2016YFF0204402), the Program for Changjiang Scholars and Innovative Research Team in the University (IRT1205).