Page 583 - IJB-10-3

International Journal of Bioprinting 4D printing & simulation for biomedicine

A weight loss measurement method using a subsequently dehydrated by passage through a series of
basic solution was used. The initial weight of the ethanol solutions (10, 30, 50, 70, 90, and 100%) at 5-min
sample of the synthesized biodegradable polymer intervals. Pt coating was performed using a sputter coater,
was measured. The sample size was 10 × 10 × 3 mm and SEM images were captured at a voltage of 10 kV.
(width × diameter × height), and the initial weight
was established as 0.2 g (± 10%) through 3D printer 2.7. Fixation and recovery rate
fabrication. Subsequently, a solution of 0.1 N NaOH, The SMP was designed to enable two types of motions,
pH 12.5, was added to an inert plastic container, and the bending and linear motion, through 3D printing. It
sample was placed in a decomposition environment at was printed using PLA+PEG 10 phr and PLA+PEG 20
a temperature of 37°C with shaking at 120 rpm. After a phr SMP compositions. The shape for bending motion
specified decomposition period, the sample was taken was fabricated as follows: a hinge shape measuring
out, washed with distilled water, and dried at 37°C, 10 × 10 × 2 mm (width × depth × height). An external
and the weight was measured. This process allowed the force was applied at a temperature higher than T to
g
evaluation of the weight ratio of the decomposed sample achieve an angle less than or greater than 90°. After
in comparison to its initial weight. The weight loss was maintaining room temperature for approximately 1 min
assessed using the following equation: while applying the external force, the cooling state was
sustained. Subsequently, the external force was removed,
and the free state was maintained for about 24 h.
Weight loss (%) = (W − W)/W × 100 (I) Following this period, a temperature higher than T was
0
0
g
applied again to return to the recovery shape. The fixation
where W represents the initial weight, and W and recovery rates of the bending motion were calculated
0
represents the weight measured after degradation. as follows:
2.5. Cell culture
NIH3T3 cells were cultured in Dulbecco’s modified Eagle’s F (%) = (C angle /F angle ) × 100 (II)
rate
medium-high glucose (DMEM) supplemented with 10%
fetal bovine serum (FBS) and 1% penicillin in an incubator R (%) = (O angle /R angle ) × 100 (III)
rate
at 37°C with 5% CO .
2
2.6. Cell viability, proliferation, and cell morphology where F refers to the fixation rate, C angle refers to the
rate
of biocompatible shape-memory polymers angle during cooling, and F angle refers to the angle when
Cell biocompatibility and viability were assessed using fixed in the free state; R refers to the recovery rate, O angle
rate
a live and dead assay. Aliquots of approximately 5 × 10 refers to the angle in the original shape, and R angle refers to
5
cells were seeded onto the samples and allowed to the angle value in the recovery state.
attach for 4 h in an incubator at 37°C with 5% CO . The The shape for linear motion was manufactured in a
2
samples were cultured for 1, 4, or 7 days, washed with sheet shape measuring 20 × 20 × 0.5 mm (width × diameter
phosphate-buffered saline (PBS) to remove the medium, × height). Similar to the bending motion, for the linear
and then stained for approximately 1 h with calcein- motion, an external force was applied by stretching both
AM to identify live cells and homodimer-1 to identify sides at the extremes by about 3 mm when a temperature
dead cells. The stained cells were observed under a above the T was applied. The SMP underwent cooling,
g
fluorescence microscope. free, and recovery state-linked bending. The fixation
and recovery rates of the linear motion were calculated
Cell proliferation was assessed by WST-1 assay.
The WST-1 solution was prepared following the as follows:
manufacturer’s instructions. The polymer with cells
was incubated with 500 μL of WST-1 solution in F (%) = (C length /F length ) × 100 (IV)
rate
a 24-well plate for 1 h. After incubation, 100 μL of
supernatant was transferred to a fresh 96-well plate, and R (%) = (O /R ) × 100 (V)
the absorbance at 440 nm (A ) was measured using a rate length length
440
microplate reader.
where F refers to the fixation rate, C length refers to the
rate
The morphology of adherent cells on the SMP was length during cooling, and F refers to the length when
length
investigated by scanning electron microscopy (SEM). fixed in the free state; R refers to the recovery rate, O length
rate
After culture of the cells with polymer for 7 days, the refers to the length in the original shape, and R length refers to
samples were fixed overnight in 4% paraformaldehyde and the length in the recovery state.
Volume 10 Issue 3 (2024) 575 doi: 10.36922/ijb.3035