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Materials Science in Additive Manufacturing 3D-printed nozzle for 3D bioprinting

Triton X-100 in PBS. The cells were then incubated for angle of the inlet needle placement reduces the possibility
30 min at room temperature, in a blocking buffer containing of clogging. The design used in this study included an
5% FBS, 0.1% Tween-20, and 0.02% sodium azide in ×1 external cell inlet holder used to extrude cells at the nozzle
PBS. Rhodamine-phalloidin (1:40 in ×1 PBS) was added tip (Figure 2B, top). This enabled the deposition of cells
to each well after discarding the blocking buffer. The cells into the construct after the gelation process occurred
were incubated for 1 h at room temperature. The cells were within the DNC mixing region. The DNC illustrated in
then washed with ×1 PBS and incubated for 5 min with Figure 2B (bottom) is for printing an acellular peptide-
4′,6-diamidino-2-phenylindole (DAPI) and sterile water based scaffold.
(1:2000, volume/volume). Images were obtained using an
EVOS microscope with ×4 and ×10 magnification using The DNC STL files were printed with FormLabs 3B
absorption and emission parameters. Assessment of the using the suggested FormLabs White Resin settings. To
cells’ morphology was performed after 1 and 3 days. eradicate any residual resin, the connectors were post-
processed using isopropanol. Subsequently, two 18G
3. Results and discussion needles were inserted into the two inlets, and another 18G
needle was cut and sanded to be inserted into the outlet.
This study highlights the apparent advantages of a DNC
extrusion system in terms of cost-effectiveness and rapid The needle assembly into the connector was done before
fabrication time. The use of resins for fabrication makes it the curing process to ensure a sealed fit. Due to the slight
extremely simple to modify, fabricate, and replace nozzles as shrinkage of the printed models during the curing process,
needed without disrupting experiments. In addition, using a tight fit between the connectors and needles was created.
a vat polymerization-based fabrication method ensures To finalize the assembly of the nozzle, an 18G needle
precision and reproducibility, which ensures consistent 3D was inserted into the DNC side holder for the cell’s inlet
bioprinting results compared to the inevitable variations in (Figure 2C). The cumulative time taken for printing and
handmade nozzles. curing a batch of 5 DNCs was estimated to be around 3 h.
3.1. Design and fabrication of DNC 3.2. Parameter optimization for 3D bioprinting
The connectors were designed to be compatible with After fabricating the DNC, several parameters needed
standard Luer lock needle tips, where the 18G needle, to be optimized to establish compatibility with peptide
equivalent to 1.2 mm outer diameter, was used for both bioinks and our robotic 3D bioprinter. These included flow
inlets and the outlet of the DNC. Furthermore, the two rate profiles, peptide and PBS concentration, and printing
inlets were designed with an angle so that they merge speed. Performance was evaluated by observing gelation
into one outlet, as illustrated in Figure 2A. The minimal continuity, printability, shape fidelity, and biocompatibility.

A B C

Figure 2. A visual representation of the DNC and the fabrication procedure of the nozzle. (A) A draft drawing showing the dimensions of the DNC and a
cross-sectional view of the inlets and the outlet of the DNC, all in mm. (B) A CAD model of the two DNCs with and without the cell inlet holder. (C) The
3D-printed DNC with the needle assembly.
CAD: Computer-aided design; 3D: Three-dimensional; DNC: Disposable nozzle connectors.

Volume 2 Issue 1 (2023) 5 https://doi.org/10.36922/msam.52