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International Journal of Bioprinting 3D-printed scaffold for biomolecule delivery3D-printed scaffold for biomolecule delivery

tissue damage from various diseases and accidents. ethanol bath as a fixative solution. To coat the surface of
3-6
Therefore, researchers are interested in exploring exogenous the scaffold, silica xerogel and composite solution were
GFs as a potential therapeutic approach for rapid repair prepared in a 1:10 molar ratio of tetramethyl orthosilicate
and healing. 3,5,7-9 However, successful outcomes in typical (Sigma-Aldrich, USA) to distilled water; subsequently, a
trials frequently appeared in therapies that involved only a gelatin (Sigma-Aldrich, USA) solution dissolved in distilled
single GF administration. 10,11 Injected GFs diffuse rapidly water was mixed with the silica solution according to the
into surrounding tissues and are degraded by enzymes in determined volume percentage (i.e., 5, 10, 15, and 20%),
the body. However, such trials are limited to small-scale which indicates the volume percent of gelatin solution in
cohort and animal studies. Furthermore, their ability the silica solution. The mixture was stirred for 2 h at 4°C. To
12
to play a role as effective mediators in the body requires obtain the bulk form, the solution was poured into a plastic
time-controlled signaling. Therefore, the development of column and dried. Cytochrome c (Cyt c; Sigma-Aldrich,
13
novel scaffolds should simultaneously address the need to USA) was used as a model protein. To improve the adhesion
be preserved in GFs to prevent rapid degradation and to of the GS composite on the PCL scaffold, norepinephrine
release them at the desired time and location. 5,14-16 surface treatment was applied. This modification enhanced
Recently, 3D printing has received great global interest the hydrophilicity of the PCL surface, facilitating stronger
as a novel technology. 2,17,18 In bone tissue engineering, the bonding between the scaffold and the composite coating.
28
application of 3D printing has been noted in the fabrication The scaffold was activated with 2 mg/mL norepinephrine
of successful patient-specific scaffolds. 19-21 Moreover, the solution dissolved in 10 mM Tris-HCl (pH 8.8) for 1 h
controlled porosity, pore size, and interconnectivity in at room temperature. The scaffold was washed with Tris-
3D-printed scaffolds have the potential to enhance the HCl and distilled water and dried to remove unreacted
exchange of nutrients and wastes, tissue ingrowth, and molecules. To envelope the GFs in the composite solution,
angiogenesis. In particular, poly-ε-caprolactone (PCL) lyophilized 100 μg/mL recombinant BMP-2 and 100 μg/
has been widely used in 3D printing systems due to mL recombinant bFGF (PeproTech EC Ltd., USA) were
its biodegradability, biocompatibility, and high ease of mixed in the composite solution for 30 min. The activated
handling. 22-27 However, incorporating GFs into a polymer 3D scaffolds were immersed in this solution for 30 min.
strut of the 3D-printed scaffolds is difficult, as the process The scaffolds were then washed with phosphate-buffered
requires a high temperature or organic solvent content for saline (PBS; Welgene, Korea) and centrifuged at 1300 rpm
dissolving the synthetic polymers.
for 1 min. After drying, the second layer was coated on the
In this study, we fabricated 3D-printed scaffolds, which pre-coated surface. The procedure for 3D printing and the
release spatiotemporally controlled GFs. The polymer predicted release of GFs from the scaffolding system are
scaffold was printed and coated with a gelatin-silica (GS) illustrated in Figure 1.
composite containing GFs on its surface. The scaffolds
were double-layered and incorporated with basic fibroblast 2.2. Characterization of the composites
GF (bFGF) in the outer layer and BMP-2 in the inner layer and scaffolds
to modulate the early and late processes of osteogenic Chemical analyses of the hybrid coatings were performed
differentiation of rat bone marrow-derived mesenchymal using an attenuated total reflectance Fourier transform
stem cells, respectively. We found the best conditions for infrared (ATR FTIR) spectrometry. The morphologies
fabricating double layers with the composite and observed of the scaffolds were observed using scanning electron
the morphology. The release of GFs from the scaffold was microscopy (SEM; JSM-6510; JEOL, Japan). The
investigated in vitro, and the cellular effects on the scaffold degradation of bulk materials was assessed by weight
were assessed using stem cells. measurements on predetermined dates for 24 days. The
release of Cyt c, selected as a representative model protein
2. Materials and methods for small, water-soluble proteins, from the bulk was
2.1. Fabrication of scaffolds and hybrid sol coating measured by assessing absorbance at a specific wavelength
A PCL (Sigma-Aldrich, United States of America [USA]) of 409 nm. The Cyt c was eluted in PBS at 37°C with
slurry was prepared by dissolving PCL in acetone (30% agitation at 150 rpm for 24 days. To visualize the bilayer
[w/v]) at 50°C. The scaffolds were designed in a square distribution of the hybrid layers, PCL scaffolds were coated
shape of 13 × 13 × 1 mm, with a pore size of 0.5 × 0.5 mm with fluorescein isothiocyanate (FITC) and rhodamine dye
and strut size of 0.25 mm. The 3D scaffolds were fabricated loaded into the composite solution. The first and second
using a computer-based robotic dispensing machine (Ez- layers contained rhodamine and FITC dyes, respectively.
ROBO3; Iwashita Engineering Inc., Japan). To solidify The results were visualized using a confocal laser scanning
the polymer solution, the slurry was printed in a 70% microscope (CLSM; LSM700; Carl Zeiss, Germany).

Volume 10 Issue 6 (2024) 445 doi: 10.36922/ijb.4638