Table 1.
Comparison table of various 3DP technologies for fabrication of three-dimensional (3D) cell scaffold.
| 3DP Methods | Chief Feature & Mechanism | Materials | Cells Studied | Architecture | Dynamic Structure Appli-Cability | Advantages | Disadvantages | Refs. |
|---|---|---|---|---|---|---|---|---|
| Two-Photon polymerization (2PP) | Laser beam is focused onto a liquid material; CAD | Solidifable fluid: photosensitive materials | Bone cells, human stem cells | Mesh-like, wheel-, pyramid-, cube-like pattern in hydrogel | High | Homogeneous and two-composite polymer | Excess of initially powdered material hard to remove | [2,35,36] |
| Laser Engineered Net Shaping (LENS) | Metal powders used to build or repair scaffold parts | Fine powder: plastic, metal etc. | General tissue cells | Mesh-like network | High | Able to repair old parts and fabricate new; secondary firing process not needed; excellent material properties | Low geometrical control in dimension | [18,37,38,39] |
| Stereolith-ography (SLA) | Laser onto liquid photopolymer to generate scaffold; CAD | Solidifable fluid: photopolymer resins, temperature sensitive polymers, ion cross-linkable hydrogels, ceramic paste, etc. | Rat bone, rabbit trachea, pig tendon cells | Mesh-like, Honeycomb- Wheel-, pyramid-, cube-like; porous cylinder | High | High surface quality, high resolution, high complexity, fast speed. | Limited to specific polymers (photopolymers); need support system; moderate strength; expensive | [36,40,41,42,43,44] |
| Selective Laser Melting (SLM) | Using small diameter wire-frame elements | Fine powder: Plastic, metal, ceramic or composite powders | Mouse bone cells | Mesh-like, Honeycomb- Wheel-, pyramid-, cube-like network | High | Controlled pore interconnectivity and porosity; greater durability of mould; free from temperature-related defects | Low surface quality | [35,40,45] |
| Selective Layer Sintering (SLS) | Laser-based CAD technique; include laser and power bed | Fine powder: Plastic, metal, ceramic or composite powders | Mouse bone, rat heart, rat bone, mouse skin, mouse heart cells | Mesh-like network, porous cylinder | High | Good mechanical strength; complex structures; high resolution; large part size; no support structure needed | High materials requirements (heat, shrinkage resistant); require high processing temperature; powdery surface; costly; time consuming | [2,40,41,42] |
| Laminated Object Manufacturing (LOM) | layers of adhesive-coated laminates being successively glued together and cut to shape with laser | Laminated thin sheet: Ceramics—alumina, silicon nitride, and zirconia and metals | General tissue cells | Mesh-like network | High | Large part size; layer builds quickly; fine accuracy and resolution low cost | Materials limited | [21,40,46] |
| Ink-jet Printing (3DP in traditional terminology) | Liquid binder jetting; drop-on-powder; CAD | Hydroxyapatite, magnesium phosphate, cement, polyurethane | Rat bone, rabbit bone and mouse bone cells | Mesh-like network; porous cylinder | High | Materials versatile; powder can be trapped inside body; don’t need support structure; high speed; cost-efficient | May be toxic; low mechanical strength compared with Laser printing; time consuming in post-processing | [2,21,28,41,42] |
| Fused Deposition Modeling (FDM) | Thermoplastic polymer through heated extrusion Nozzle to create scaffold onto platform; CAD | Non-brittle flament: Thermoplastics like ABS, PLA, and PCL etc. | Rat and Swine Bone cells | Mesh-like network; porous cylinder | High | Relatively inexpensive; low cytotoxicity; good strength; no support structure needed; no power trapped; good mechanical anisotropy; speed control by strand diameter | Limitation on materials (thermoplastics); materials non-biodegradable; support structure required for complex geometrics; post possessing needed; low resolution; low speed | [2,21,28,41,42] |
| 3D Plotting (Bioplotter Printing) | Air pressured system to extrude material from bioink cartridges | Solidifable fluid: ion cross-linkable hydrogels etc. | Rabbit cartilage, rabbit trachea, rat cartilage, mouse cartilage, mouse skin cells etc. | Mesh-like network; dot-like structure | High | Viable cells printable; soft tissue applications; wide variety of natural and synthetic materials; processing at room temperature | Nozzle may be cytotoxic; support structure required when printing complex structure; low dimensional accuracy | [22,28,40] |
| Wax Printing (Indirect 3DP) | Wax being printed as a negative mold where scaffold solution is cast | Wax | Rat bone cells, mouse stem cells | Mesh-like structure | High | Benefit on preproduction; versatility on material casting following obtained mold | Materials may fail to be biocompatible; Low resolution; always need a mold; low speed in fabrication | [41,45] |
| Conventional Methods | Chief Feature & Mechanism | Materials | Cell Studied | Architecture | Dynamic Structure Appli-Cability | Advantages | Disadvantages | Refs. |
| Electrospinning | Polymer solution forced into a capillary to form a jet of solution a tip; high voltage applied between tip and collector | Biodegradable polymers like PCL | Rat bone, mouse bone, rabbit vascular tissue cells | Mesh-like structure; microchannel | Low | Fast speed; cell printing available; soft tissue application; similar to ECM; better mechanical control (shear stress); high aspect ratio and surface area | Fibers printed in random orientation; pore sizes not uniform; high voltage demand; organic solvent needed | [2,41,42] |
| Solvent Casting/Particulate Leaching | Dissolute polymer in an organic solvent and casting into a mould | Composite like PLA/Calcium phosphate | Bone cells | Mesh-like structure | Low | High geometric control; easy processing; fast speed | Organic solvents have to be used | [42,47] |
| Phase Separation | Polymer and solvent mixed pass through a freeze-dryer | Ceramics, i.e., glass | Bone osteoblast cells | Homogeneous and highly porous structures | Low | High porosity; easy to cooperate with other techniques | Possible shrinkage issues; organic solvents used; anisotropic pores | [42,45,48] |
| Gas Forming | Using a process with high-pressure carbon dioxide at room temperature | Polyesters polymers; biodegradable polymers | Bone cells | Mesh-like; microchannel | Low | Organic solvents not needed; room temperature processing; macro-porous scaffold | Poor geometrical and porous control | [23,42,45] |
| Microsphere Sintering | Sintering polymer microspheres thermally or chemically | Polymers | Bone cells | Mesh-like; microchannel | Low | Pore size being gradient; complex shape fabricable | Lack of control in interconnectivity | [42,45,49] |
Note: Green represents 3DP laser-based technologies, orange for droplet- or powder-based and yellow for nozzle-based ones. Grey colour represents traditional tools for scaffold fabrication.