A Floating Self-Assembly Route to Colloidal Crystal Templates for 3D Cell Scaffolds

Abstract

Preparation of well-ordered three-dimensional (3D) scaffolds is of great importance for various aspects of tissue engineering and fundamental research in cell biology. A versatile technique, floating self-assembly, is reported here for the first time to prepare 3D colloidal crystals from polystyrene particles of various diameters (10-240 µm). Ethylene glycol was used as the solvent in the self-assembly process of colloidal crystals. Polymer colloidal particles float on the surface of ethylene glycol and self-assemble into a hexagonal crystal lattice structure. The slow evaporation of ethylene glycol left solvent-free 3D colloidal crystals. Na 2 SiO 3 sol-gel solution was infiltrated into the interstitial space of the prepared colloidal crystals, taking advantage of the capillary effect, and an inverse opal with a highly ordered system of spherical cavities interconnected by channels was obtained by calcining the colloidal particles at high temperature. As-prepared inverse opals were used as 3D cell scaffolds which possess a high degree of order compared to existing foamlike and fibrous cell scaffolds and afford tight control over the scaffolds' porosity and tissue organization. Their preparation by this technique is much simpler than that by freeform fabrication techniques. The biocompatibility of the prepared cell scaffolds is demonstrated through human hepatocellular carcinoma HEP G2 and human bone marrow HS-5 cell cultures.

Design and fabrication of colloidal polymer nanocomposites

“…In addition to substrate patterning, electrostatic [48], external electric field [49,50], floating self-assembly [51], centrifugation [52], filtration [53], and other methods [54][55][56] have all been investigated as a means for colloidal particle assembly. For example, in Figure 5 [51,52] there are examples of three-dimensional structure obtained from floating self-assembly and centrifugation, respectively.…”

“…For example, in Figure 5 [51,52] there are examples of three-dimensional structure obtained from floating self-assembly and centrifugation, respectively.…”

“…A porous inorganic structure is left behind, and this inverse opal structure can serve as a template for other nanomaterials or 3D scaffolds for cell or tissue engineering. [51,[141][142][143] Most existing cell and tissue scaffolds have the drawbacks of having a poorly ordered or even chaotic structure, requiring a complex fabrication process, and using a limited materials selection. The 3D scaffolds fabricated from colloidal nanocomposite networks allow the facile design of porosity, interconnectivity and pore size.…”

Towards uniformly oriented diatom frustule monolayers: Experimental and theoretical analyses

“…A variety of self-assembly approaches have been reported, including the assembly of particles with a range of sizes and shapes [21][22][23] . Special attention has been paid to the 'floating assembly' of micronanoparticles floating on liquid-air interfaces [24][25][26] , as this technique is technically relatively simple and produces high-quality monolayers or even 3D assemblies of particles. It has been reported that the success of the floating assembly results from the capillary forces between the floating particles 27,28 .…”

Bioinspired Pollen‐Like Hierarchical Surface for Efficient Recognition of Target Cancer Cells

“…[15] Without ethylene glycol addition, the assembled pollen grains cracked after drying ( Figure S3 in the Supporting Information). We also tried other methods of self-assembly, such as vertical deposition, [16] floating self-assembly, [17] and liquid interface-mediated assembly, [18] but failed to assemble the pollen grains into a large-scale and crack-free pollen layer ( Figure S4 in the Supporting Information). These results show that a close-packed and large-scale pollen layer has been successfully fabricated by using the filtering-assisted assembly.…”