Three-dimensional magnetic assembly of microscale hydrogels

Directed assembly of nano and microscale particles is of great interest and has widespread applications in various fields including electronics, nanomaterials and tissue engineering. Bottom-up tissue engineering is motivated by the occurrence of repeating functional units in vivo. The bottom-up approach requires novel techniques to assemble engineered functional units as building blocks at a high speed with spatial control over three-dimensional (3D) micro-architecture. Here, we report a magnetic assembler that utilizes nanoparticles and microscale hydrogels as building blocks to create 3D complex multi-layer constructs via external magnetic fields using different concentrations of magnetic nanoparticles. This approach holds potential for 3D assembly processes that could be utilized in various tissue engineering and regenerative medicine applications.