Page 521 - IJB-9-5

International Journal of Bioprinting 3D printability and biochemical analysis of orange peel waste

Figure 1. 3D printing of orange peel waste (OPW) by direct ink writing (DIW). (A) Flowchart describing the process to fabricate 3D-printable OPW inks
and indication of nutritional analysis along the crucial steps of fabrication. (B) A photograph of a DIW 3D printer used in the experiment, equipped with
a syringe attached to a pneumatic dispenser.
which was diluted with approximately 42.5 mL of methanol measured at 734 nm using the Multiskan GO microplate
[31]
to give an initial absorbance of approximately 0.70–0.80 reader (Thermo Scientific, Singapore) .
at 734 nm . Ascorbic standard curve (100 μM–1 mM)
[35]
was generated to produce 5%–50% inhibition of the blank 2.8. Cell viability
Human dermal microvascular endothelium (HMEC-1) cells
absorbance (ABTS•+ alone) . Subsequently, 25 μL of were obtained (American Type Culture Collection [ATCC],
extracts from orange peel powder, ink, and printed samples USA) and cultured in MCBD-131 media (20% fetal bovine
were added to the 96-well microplate containing 200 μL serum [FBS], 5% L-glutamic acid [200 mM], 1% penicillin-
of ABTS•+ solution. All experiments were performed in streptomycin and 0.001% recombinant human epidermal
triplicates . The reaction was incubated for 30 min at growth factor [EGF; 10 ng/mL]) using T75 flasks at 37°C, 5%
[31]
25°C with low-frequency shaking, and absorbance was CO [31,32] . At 75%–85% confluency, cells were seeded into cell-
2

Volume 9 Issue 5 (2023) 513 https://doi.org/10.18063/ijb.776