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International Journal of Bioprinting Printing collagen type IV membrane

Figure 1. Collagen type IV (Col-IV) ink printability evaluation. (A) Rheological analysis of photo-crosslinked Col-IV solution revealed increased storage
modulus (G’) with ultraviolet (UV) exposure. The arrow indicates the start and end of photo-crosslinking; the dashed line indicates the time G’ reaches
the plateau. (B) Viscosity analysis indicates shear-thinning behavior. (C) A representative image of the printed two-layered Col-IV lattice structure using
optimized printing conditions. Error bars represent standard deviations (SD) in all graphs. Scale bar: 1 mm. Abbreviation: G”: Loss modulus.

123.4 ± 27 µm (for printed) with no significant difference The Col-IV membranes (n = 3; thickness: 117, 119,
between the two fabrication methods. The line spacing of and 158 µm) exhibited an average light transmittance
the print was reduced from 0.5 mm to allow the newly (400–700 nm) of 97.8 ± 0.5% (Figure 2B). The light
extruded bioink to fuse with adjacent extruded ink transmittance percentage exceeded the reported human
and eliminate the step pattern. Surface roughness is an cornea data, which is at approximately 80%. SEM
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important characteristic of the membrane, as increased results revealed that the membranes had a dense, sheet-
roughness of corneal endothelial transplants was found like micro-network (Figure 2C). The compression
to reduce optical quality and impede visual recovery. test indicated that the elastic modulus of the Col-IV
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The RMS for printed membranes was 1.5 ± 0.7 µm, which
was significantly lower than that of molded membranes, membrane was 49 ± 14 kPa. The tensile test reported that
averaging at 3.9 ±1.8 µm (p < 0.01). Printed membranes also the elastic Young’s modulus of the Col-IV membrane
demonstrated a lower RMS than the average endothelial was 89.5 ± 23.9 kPa, while the surgically removed human
transplants at 3.65 µm. This indicated that the printed corneal Descemet’s membrane has an elastic Young’s
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Col-IV membrane’s surface is smoother than an average modulus of 40.2 ± 5.9 kPa. This suggests that the printed
endothelial graft. Herein, unless specified otherwise, the Col-IV membranes have approximately twofold higher
term membrane(s) refers to printed membrane(s). tensile strength than Descemet’s membrane.

Volume 10 Issue 4 (2024) 162 doi: 10.36922/ijb.3258