Table 5.
Biomaterials used for extrusion based bioprinting.
| Materials | Process | In Vivo/In Vitro Model | Key Findings | Ref. |
|---|---|---|---|---|
| Gelatin (partially crosslinked) | The partially polymerized gel in the print head was extruded at 30 °C through a 100 µm diameter nozzle on to a cooled platform (10 °C). These were later crosslinked with chemicals EDC/NHS * for thermal and mechanical stability. Sterilization was done by overnight incubation in 70% ethanol and one hour of UV exposure. | CD-1 strain (Harlan) female mice | 3D printed implant restored ovarian function in the sterilized mice. Additionally, these mice successfully bore offspring. | [21] |
| Nano-fibrillated cellulose (NFC) + alginate | Using regenHU bioprinter, scaffolds (4.8 mm × 4.8 mm × 1 mm) were printed at printing pressure 40 kPa and 5 mm/s printing speed. Crosslinked using CaCl2 for 10 min, followed by rinsing with culture medium. | Human nasoseptal chondrocytes | Successfully 3D printed constructs resembling human organs (ear). The cytotoxicity and cell viability analysis proved the biocompatibility of this novel hydrogel (bioink) formulation. | [22] |
| NFC + alginate; NFC + HA | RegenHu bioprinter was used to 3D print the constructs of 7 mm × 7 mm × 1.2 mm dimensions with the two bioinks loaded with iPSCs. Printing speed was maintained at 10–20 mm/s at 20–30 kPa printing pressure. NFC-alginate constructs were crosslinked with CaCl2 for 5 min and NFC–HA constructs were crosslinked for 5 min using H2O2. | Human derived induced pluripotent stem cells (iPSCs) | The iPSCs in NFC-alginate constructs were pluripotent for at least 5 weeks, and then formed into hyaline like cartilage expressing type II collagen. NFC-hyaluronic acid constructs have shown lower proliferation rate. | [23] |
| Methacrylated hyaluronic acid (MeHA) | MeHA was dissolved in culture medium along with photoinitiator Irgacure 2959. Porous cubic scaffolds were bioprinted using Bioscaffolder dispensing system 3D bioprinter and scaffolds were UV crosslinked at 1800 mJ/cm2. | Mesenchymal stromal cells | Bioprinted scaffolds maintained good cell viability for more than 3 weeks. Increased concentrations of MeHA promoted osteogenic differentiation. | [31] |
| PVA and phytagel (1:1) | Printing was done at room temperature with a print speed of 5 mm/s and flow rate of 6 mL/h on to a cold build plate (−78.5 °C). The scaffolds were stored at −25 °C for 15 h. Constructs were later coated with collagen, poly-l-lysine or gelatin | Human dermal fibroblast cells | PVA/phytagel hydrogel was successfully 3D printed cryogenically and have mechanical properties similar to soft tissue. Additionally, coating with natural polymers (chitosan or gelatin) increased the cell attachment of the fibroblasts | [24] |
| Biphasic calcium phosphate (HA/β-TCP = 60:40) + HPMC + Polyethylenimine + ZrO2 | Extruded at pressure of 600 kPa and at printing speed of 100 mm/min. Samples were sintered at 1100 °C | Tested on osteoblast like sarcoma cells for cytotoxicity and hMSCs for differentiation potential of the scaffolds | Improved mechanical properties of scaffolds at 10% (w/w) of ZrO2 was reported along with improved BMP-2 expression | [32] |
| Calcium sulfate hydrate + mesoporous bioglass + PCL | Extruded under pressure of 2.2–3.6 bar and speed of 4.5–8.2 mm/s | In vitro evaluation on hBMSc cells and in vivo evaluation on rat model | Addition of bioglass promoted bone formation significantly in the animal model | [33] |
| Calcium silicate + Magnesium + PVA | Extruded using a 450 µm nozzle and printed at speed of 6 mm/s. Scaffolds were sintered at 1150 °C | In vitro testing on MC3T3 cells an in vivo evaluation on rabbit skull defects | Mechanical strength was significantly improved along with degradation rate and new bone formation | [34] |
* EDC/NHS—(1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride)/N-hydroxysuccinimide; HPMC—(hydroxypropyl methylcellulose); hMSCs—(human mesenchymal stem cells); hBMSc—(human bone marrow stromal cells).