Fig. 5. PEG based bioprinting.

(a) The custom microcapillary tube adaptor and printing protocol for building a cellularized tubular structure, consisting of depositing hydrogel macrofilaments in a stacked manner; (b) (i) Immediately after printing (ii) At 14 days, and (iii) At 28 days of culture using LIVE/DEAD staining to highlight viable and dead cells [141] with permission form Elsevier, copyright 2010; (c) (i) Schematic diagram showing two step crosslinking processes of the bioink, (ii) Schematics showing the procedure of bioprinting perfusable hollow tubes with the bioink (iii) The designed multilayered coaxial nozzles; (d) Fluorescence micrographs showing the bioprinted perfusable tubes displaying different outer diameters; (e) Fluorescence photographs before (inset) and after injection with red fluorescent microbeads into the lumen of the single, continuous bioprinted tube (f) Fluorescence photographs showing bioprinted perfusable tubes with various shapes; and (g) Photographs showing single tubes bioprinted with a gradually increasing size (i) and periodically varying sizes (iii) the high-magnification fluorescence micrographs in (ii and iv) clearly show the varying diameters at selected locations indicated in (i and iii), respectively [142] with permission from Elsevier, copyright 2016. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)