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International Journal of Bioprinting 3D bioprinting of collagen hydrogels

Figure 1. Schematic representation of an in situ extrusion 3D-bioprinted collagen scaffold. Abbreviation: LAP: Lithium phenyl-2,4,6-
trimethylbenzoylphosphinate.

for another 12 hrs, and finally in ultra-pure water for CML-Ink. It provides a consistent baseline for comparing
three days. After achieving neutrality through dialysis, 40 the CML-Ink’s gum-forming properties, extrudability,
μL MA was added to the collagen solution. After thorough dynamic viscosities, and mechanical strength. This
mixing, LAP was added to achieve a final concentration of comparison allows for an accurate assessment of how the
0.2% (w/v), obtaining the collagen-based biomaterial ink addition of MA and LAP affects the collagen’s behavior,
(CML-Ink) for extrusion-based 3D printing. ensuring that any observed changes are attributable to
the ink’s modifications. This systematic approach helps in
2.3. Characterization of CML-Ink understanding the effectiveness of crosslinking and the

2.3.1. Selection of CML-Inks biomaterial’s suitability for various applications.
The dialyzed 10 mg/mL collagen was mixed uniformly with 2.3.2. Evaluation of gelation performance
0.2–0.5% (v/v) MA and 0.1–0.4% (m/v) LAP solutions to Both Col and CML-Ink, each at a concentration of 10 mg/
prepare different ratios of CML-Inks. mL, were placed in separate vials. The gelation status was
The CML-Inks were loaded into 5 mL injection observed using the inverted vial method both before and
syringes, each equipped with a needle featuring an inner after 10 s of 405 nm light irradiation.
diameter of 0.25 mm. This setup was utilized to examine 2.3.3. Extrudable properties of CML-Ink
the extrusion states of the CML-Inks. Rheological tests A needle with an inner diameter of 0.6 mm was chosen
were conducted to assess the mechanical strength of the as the standard for extrusion testing of the CML-Ink. The
dynamic mechanical properties of these CML-Inks before CML-Ink was loaded into a 5 mL syringe and extruded
and after illumination.
to spell the word “Col,” and the extrusion process was
Using a collagen solution (Col) as a reference is crucial conducted under 405 nm blue light irradiation, with
for evaluating the properties and performance of the accompanying photographic documentation.

Volume 10 Issue 5 (2024) 544 doi: 10.36922/ijb.4069