Fig. 3.

Schematic of two different 3D bio-printing methods and major functions. (a) Extrusion-based 3D printing set-up. (b) Coaxial nozzle set-up for 3D printing. (a, b) Reproduced with permission [74]. Copyright 2021, John Wiley and Sons. (c) Inkjet-printing set-up. (c) Reproduced with permission [82]. Copyright 2021, John Wiley and Sons. (d) Schematic introduction on the manufacturing process of the nano diamond/polycaprolactone (ND/PCL) NGC and its in vivo performance. (e) Elasticity evaluation of ND/PCL and PCL NGCs. (f) The average elongation at break of ND/PCL and PCL NGCs. (d–f) Reproduced with permission [84]. Copyright 2019, Springer Nature. (g) Illustration of the layer-by-layer casting method of the graphene NGC. (h–k) SEM images of the nano porous and the multi-layered 3D structure of the graphene NGC. (g–k) Reproduced with permission [85]. Copyright 2018, Springer Nature.