Page 365 - IJB-9-6

International Journal of Bioprinting Surface modification of PCL scaffolds

growth [22,26] . In order to improve the interaction between cell proliferation. Besides, the results of the live/dead test
scaffolds and tissues, several methods have been employed suggest that surface modification did not have a negative
to enhance the surface properties of PCL. These methods impact on cell viability, as there was no significant difference
include covalent grafting, plasma treatment, and surface in cell viability between the two groups. Vinculin, a protein
coating [33,34,38] . Of these, alkaline treatment stands out as a found in focal adhesions (FA), is closely linked to a cell’s
simple and effective way to modify both the physical and adhesive capacity . The current study demonstrated that
[48]
biological properties of scaffolds. BMSCs grown on M-PCL scaffolds produce more vinculin
and filopodial protrusions compared to those grown on
Compared to bulk hydrolysis, NaOH treatment is a PCL scaffolds. This may be attributed to the presence of
surface hydrolysis method with a slower rate of NaOH nanopits and nanogrooves on the M-PCL scaffolds, which
diffusion into the polymer matrix, resulting in a higher offer more anchoring points for cells.
surface hydrolysis rate . It has been reported that the bulk
[41]
properties of the scaffolds remained unchanged despite the Finally, we investigated the impact of surface
hydrolysis treatment [13,38] . The present study utilized XRD, modification on the osteoinductive properties of PCL
FTIR, and EDS to investigate the crystalline structures scaffolds. Our findings revealed that M-PCL scaffolds
and chemical information of scaffolds, with a focus on could enhance the expression of osteogenesis-related
the effects of surface hydrolysis. The results of FTIR genes, mineralization, and ALP activity in vitro, as well
analysis showed that hydroxyl groups bound to the PCL as promote bone formation in vivo. Previous research has
chain following NaOH treatment. However, XRD analysis only focused on evaluating the effects of alkaline treatment
indicated that the pattern of M-PCL was similar to that on the physicochemical properties and cytocompatibility
of PCL, suggesting that the crystallinity of both scaffolds of PCL. This study is the first to explore the underlying
remained similar after NaOH treatment. These findings mechanism behind the osteoinductive effects of NaOH-
confirm that NaOH treatment did not alter the bulk chain treated PCL scaffolds. Previous studies have found that
of PCL and was an effective surface modification strategy. 3D-printed titanium scaffolds with a surface roughness
of approximately 110–1300 nm can promote osteogenic
According to reports, the application of alkaline differentiation of BMSCs [49-51] . According to reports,
treatment has an impact on certain physical properties filopodial protrusions have the ability to initiate integrin
of PCL such as surface wettability, roughness, and clustering and recruit focal adhesion (FA) proteins. This
morphology [38,40] . The surface of PCL undergoes a breakage process transforms mechanical signals into chemical
of ester bonds when treated with NaOH, leading to the signals, ultimately leading to stem cell differentiation . In
[45]
formation of functional hydroxyl and carboxyl groups. this study, the surface roughness of M-PCL was found to be
This process ultimately enhances the hydrophilicity approximately 300 nm, which falls within the desired size
of PCL . The AFM analysis results indicated that the range. Furthermore, BMSCs on M-PCL scaffolds exhibited
[47]
surface roughness of PCL scaffolds increased after NaOH a greater number of filopodial protrusions that were longer
treatment, which could be attributed to the alteration in in length. Based on these results, it can be inferred that
surface morphology. SEM images revealed that the surface the surface-modified PCL scaffolds possess an optimal
of M-PCL scaffolds exhibited a rough microstructure due surface roughness that facilitates filopodia anchoring and
to the presence of nanopits and nanogrooves, whereas the subsequently influences downstream signaling pathways
surface of PCL scaffolds appeared smooth. to promote osteogenic differentiation. However, the

In addition to physical properties, the biological mechanisms behind the osteogenic properties of surface-
properties of PCL can also be affected by alkaline modified PCL scaffolds were unclear. To investigate this,
treatment-mediated surface modification. As a result, we transcriptome analysis was performed. The results showed
conducted further investigation to determine the impact that the alkaline treatment-modified surface facilitated
of surface modification on cell proliferation, viability, osteogenic differentiation through the integrinα2/β1-
and adhesion. It is widely recognized that the low surface PI3K-Akt signaling pathway. Altogether, the results suggest
hydrophilicity of PCL hinders cell proliferation . The that alkaline treatment is a straightforward and efficient
[41]
surface hydrophilicity of PCL scaffolds was increased technique to improve the osteogenic properties of MEW
after NaOH treatment, leading to a higher proliferation PCL scaffolds.
rate of BMSCs on M-PCL scaffolds from days 1 through 5. Conclusion
7. However, there was no significant difference in the
proliferation rate between the two groups on day 14. This This study introduces a simple and effective NaOH treatment
may be due to the fact that the pores of both scaffolds were method to improve the bioactivity of the MEW PCL
filled with cells, leaving no additional space for further scaffold. The treatment increases the surface wettability and

Volume 9 Issue 6 (2023) 357 https://doi.org/10.36922/ijb.1071