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International Journal of Bioprinting Dual tuning of 3D-printed SilMA hydrogel

Table 1. Three-dimensional printing parameters structures of the hydrogels were then observed with an
orthostatic microscope (DM6 B, Leica, Germany).
Project Parameter
Digital model 2.5.2. Swelling properties
Low-temperature cylinder Cell-laden poly(ethylene oxide)/ Hydrogel samples (diameter = 10 mm, height = 3 mm)
nanofiber/silk methacryloyl bio-ink were prepared, and their initial weights were recorded as
Print parameter M0. Each group of hydrogel samples was transferred into
Printing model Lattice shape a 12-well plate, and 3 mL of PBS solution was added to
each well. The plate was placed in a constant-temperature
Cube dimension 6.6 × 7.8 × 3.0 mm incubator at 37°C. The samples were removed at the
Pattern filing Cross-mesh predetermined time points (1, 3, 6, 9, 12, and 24 h), and
Strand spacing 0.6 mm excess surface moisture was quickly absorbed using highly
Layer height 0.6 μm absorbent filter paper. The samples were photographed,
Number of layers 4 and the observations were recorded. The samples were
Temperature 25.0°С weighed again, and the weights were recorded as M1. The
Print parameter swelling ratio of the hydrogel was calculated using the
Layer thickness 0.02 mm following formula in Equation I:
Base layer count 5
(M1−M0) / M0 × 100% (I)
Base exposure time 30 s
Exposure time 8 s
Transition layer count 0 2.5.3. Mechanical test
Transition type Linear The mechanical properties of each group of hydrogels were
Transition layer delay 0 s measured using a universal material compression machine
Base lifting delay (before) 2 s (RIGOL, China). Cylindrical samples (diameter = 10
Base lifting delay (after) 0.5 s mm, height = 6 mm), prepared using silicon molds, and
Base retract delay 2 s 3D-printed grid-like samples (described in Section 2.4)
were subjected to uniaxial compression testing at a rate
Lifting delay (before) 2 s of 5 mm/min. Stress–strain curves/elastic modulus were
Cross-linking Blue light (405 nm, 20 mW/cm )
2
obtained (n = 3). The compressive modulus was calculated
Print platform as the slope of the linear elastic region within the 20–40%
Resolution X:1920 pixels and Y: 1080 pixels strain interval of the stress–strain curve. To evaluate
the fatigue resistance of the 3D-printed scaffolds, cyclic
SilMA hydrogels, and soaked PEO/SilMA hydrogels were compressive loading-unloading tests were conducted
lyophilized and ground into powder. Each sample was under 50% strain for 500 consecutive cycles at a rate of 5
mixed with a small amount of finely ground LiBr and mm/min, without intermittent recovery periods.
exposed to infrared light for FTIR detection. 2.5.4. Rheological measurements
The light-curing properties of the gel precursors were
2.5.2 Morphology and porosity evaluated through rheological analysis. Dynamic
A scanning electron microscope (SEM) (Model: rheological experiments were conducted using a rotational
GeminiSEM 300, ZEISS, Germany) was used to observe rheometer (Anton Paar, Austria) equipped with a 25 mm
the internal structure of each group of hydrogels and the measuring rotor to assess the rheological properties of the
distribution of NFs (15 kV accelerating voltage). The SEM PEO/NF/SilMA composite hydrogels at 25°C. The gel point
images were statistically analyzed using ImageJ software test was performed in time–scan oscillation mode under
(version 1.51j8) for pore size and porosity of each group 10% strain, 1 Hz frequency, and a 0.5 mm gap, with UV
of hydrogel structures with and without microporous illumination for 100 s. The gel point was determined as the
structures (n = 3). The pore size structures and PEO intersection of the curves where the storage modulus (Gʹ)
emulsion droplets in the hydrogels were directly observed surpassed the loss modulus (G˝). For the amplitude scan,
using optical microscopy (DM6 B, Leica, Germany). The the Gʹ and G˝ were measured by maintaining a constant
hydrogels were labeled with rhodamine-B, followed by frequency at 10 rad/s and varying strain values from 0.01
hematoxylin and eosin (HE) staining. The microporous to 1%. For the frequency scan, Gʹ and G˝ were measured

Volume 11 Issue 4 (2025) 281 doi: 10.36922/IJB025140118