Biofunctional colloids and their assemblies

Colloidal particles are used as elemental building blocks to construct biofunctional nanostructures. In particular, multidimensional periodic arrangements of colloidal particles such as planar arrays and spherical assemblies can be used in a wide range of biological fields. The spatial regularity of such structures at the submicron-scale gives rise to special features such as a photonic bandgap (PBG) and selective permeability, which cannot be achieved by single colloidal particles. Recent advances in microfluidics technologies enable the fabrication of designed microparticles of equal size and shape in a continuous manner. Such microparticles have great potential for use in high-throughput screening and immunoassays. In this article, we review the current state-of-the-art in regard to colloidal assemblies and microparticles prepared by microfluidics for biological applications. This review consists of five main sections: (1) surface modification methods, (2) two dimensional (2D) and (3) three dimensional (3D) colloidal assemblies, (4) confined regular structures, and (5) novel fabrication strategies for advanced colloidal assemblies. In each section, we discuss not only the fabrication routes for biofunctional materials but also the characteristics of the materials and their biological applications. Finally, we outline the future perspectives for biofunctional colloidal materials.