Recent advances in 3D printing of biomaterials

Abstract

3D Printing promises to produce complex biomedical devices according to computer design using patient-specific anatomical data. Since its initial use as pre-surgical visualization models and tooling molds, 3D Printing has slowly evolved to create one-of-a-kind devices, implants, scaffolds for tissue engineering, diagnostic platforms, and drug delivery systems. Fueled by the recent explosion in public interest and access to affordable printers, there is renewed interest to combine stem cells with custom 3D scaffolds for personalized regenerative medicine. Before 3D Printing can be used routinely for the regeneration of complex tissues (e.g. bone, cartilage, muscles, vessels, nerves in the craniomaxillofacial complex), and complex organs with intricate 3D microarchitecture (e.g. liver, lymphoid organs), several technological limitations must be addressed. In this review, the major materials and technology advances within the last five years for each of the common 3D Printing technologies (Three Dimensional Printing, Fused Deposition Modeling, Selective Laser Sintering, Stereolithography, and 3D Plotting/Direct-Write/Bioprinting) are described. Examples are highlighted to illustrate progress of each technology in tissue engineering, and key limitations are identified to motivate future research and advance this fascinating field of advanced manufacturing.

Keywords: 3D Printing; 3D plotting; Bioprinting; Computer-aided tissue engineering; Fused deposition modeling; Selective laser sintering; Stereolithography.

Figure 1

3D Printing schematic. 3D printing is a layer-by-layer process of depositing liquid binder onto thin layers of powder to create a 3D object. Reproduced with permission from [11].

Figure 2

PLGA scaffold with villi-shaped pillars created from indirect 3D Printing. Scaffolds are created by packing a 3D printed mold with porogen and polymer dissolved in solvent by indirect 3DP. The resulting scaffolds have the desired villi-shaped pillars (a) and high porosity and interconnectivity (b). Reproduced with permission from [17].

Figure 3

3D printed scaffolds can be patient-specific. A zygoma was generated from CT 2D images (a,b) and zygoma-shaped scaffold was produced from indirect 3DP (c). Reproduced with permission from [17].

Figure 4

Fused deposition modeling schematic. In fused deposition modeling, a filament of thermoplastic is heated into liquid and extruded through a nozzle in a specific lay-down pattern to create a scaffold. Reprinted with permission from [39].

Figure 5

Stereolithography schematic. Stereolithography is the polymerization of photocurable resin by a bottom-up system with scanning laser (left) or top-down setup with digital light projection (right). Reproduced with permission [59].

Figure 6

Selective laser sintering schematic. Selective laser sintering uses a laser to fuse together powder particles to create a 3D scaffold. Thin layers of powder are spread between each fused layer. Reprinted with permission from [83].

Figure 7

Bioprinting schematic. In bioprinting, small balls of bioink composed of cells and hydrogel materials (e.g. alginate or decellularized extracellular matrix) are printed in a desired shape. Reproduced with permission from [11].