Colloidal clusters of icosahedrons and face-centred cubes

Synthetically colloidal clusters with new functions and well-controlled size distribution can in principle be constructed using colloidal particles. The building units could be integrated into dense-packed and desired structured with novel functions by means of an efficient strategy or binding patterns. Here we synthesized colloidal clusters of icosahedrons and long-range ordered face-centered cubes (FCCs) via emulsion self-assembly using fluorescence upconversion nanoparticles NaGdF 4 : Yb 3+ , Er 3+ as building blocks. The icosahedrons and FCCs structure may generate spontaneously due to an entropy-driven process. The morphology and structure of colloidal clusters have noticeable transformation from icosahedron-like symmetry to FCC symmetry with the increasing size of clusters. Furthermore, the colloidal clusters could be decorated with cationic polyethyleneimine (PEI) via electrostatic interaction . When copper ions are added, the amino groups of PEI could coordinate with Cu 2+ forming low toxic PEI-Cu 2+ layers, which can further serve as energy receptors to quench upconversion fluorescence with 980 nm laser excitation. Our results reflect that the colloidal clusters not only can serve as a fluorescence platform of detection and analysis but also may represent advancement in the field of colloidal and interface sciences .