Creating 3D Structures with Molding Tools

3D structures made of collagen using mold design and fabrication

Matrix proteins are an important aspect of maintaining signaling cascades necessary for growth and homeostasis within 3D cellular environments. However, native matrix materials such as collagen contain properties that make it difficult to extrude and subsequently maintain shape fidelity during the 3D bioprinting process. The ability to place materials that are difficult to print within a mold that is fabricated makes it possible to generate complex 3D structures consisting of native matrix materials such as collagen. TSIM® contains a tool which creates a mold around a structure of interest, and properties regarding the mold are sent to the BioAssemblyBot® for 3D fabrication.

The Process

A structure of interest is created within TSIM® based upon experiment design requirements. The mold tool is then used to create a mold around the structure. This mold can then be modified to limit the material required to generate the structure. Material parameters are then assigned, followed by 3D printing of the mold structure using the BioAssemblyBot®. After the final desired product is achieved, the desired material is then delivered to the mold. After the entire structure is placed within solution, the mold is dissolved away, leaving behind a structure made of native matrix material.

Creating a mold around a structure of interest

In this example, a structure is created de novo using the different shape tools within TSIM®. The shapes are then brought together through Boolean operations (Combine two objects tool) creating the final structure of interest. Once this structure is selected, the Create a mold tool is used to generate a mold around the newly created objected. It will create a square mold around the object, after the mold is generated, it will behave as an independent object, and can be manipulated as desired. After the desired location and structure is finalized, a material is then assigned to the structure including necessary print parameters for the successful fabrication of the design.

Left panel: De novo structure creation through shapes and Boolean operations. Center panel: Mold tool is used to create a mold of the structure. Right panel: Molding process in TSIM.

3D fabrication of a structure using native matrix material

Mold structure 3D printed using BioAssemblyBot®.

Mold filled with liquid collagen.

Gelled collagen created using mold design.

The design and print parameters created within TSIM® are sent to the BioAssemblyBot® for 3D fabrication. In this example, the mold structure is created using a pluronic hydrogel printed with a petri dish. Type I collagen was then poured into the structure quickly to ensure the collagen remained cold and therefore not yet gelled while placing it within the mold. The petri dish was then placed in an incubator for 2 hours to gel the collagen within the pluronic mold. Hank’s balanced salt solution was then poured into the petri dish which was then placed in the incubator overnight to dissolve away the mold. What was then left behind was only the final structure made of collagen.

The utilization of the mold functionality within TSIM® enables 3D structure creation using native matrix materials that are difficult to utilize in the 3D bioprinting process of fabrication. Cell populations can then be placed and grown within these structures, thereby providing the ability to create defined 3D regions of cell populations to localize different cell types for studies in cell-cell interactions, cell migration, growth, or to precisely place different cell populations for whole tissue generation.

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To learn about the BioAssemblyBot 400, click here.