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Biomaterials

Biomaterials - Poster Session B

Poster C8 - Fabrication of a Two-layered Hydrogel and Zein/Poly(ε-caprolactone) Scaffold

Thursday, October 24, 2024
2:45 PM - 3:45 PM EST
Location: Exhibit Hall E, F & G

Introduction:  Efforts to enhance the performance of biomaterial scaffolding in tissue engineering have increasingly focused on improving hydrophilicity to promote cellular adhesion and proliferation.1 Zein, a non-nutritional protein derived from corn, and poly(ε-caprolactone) (PCL), a synthetic polymer with high flexibility and tensile strength, offer a promising platform for tissue regeneration. However, their more hydrophobic nature could become a factor that limits their application in biomedical settings.2 This study sought to improve the overall hydrophilicity of zein/PCL scaffolds by incorporating hydrophilic polymers through a two-layered electrospinning approach.

Materials and

Methods:  A 10% zein-30% PCL (g/mL) in a 2:2:2 of dichloromethane (DCM) to dimethylformamide (DMF) to glacial acetic acid (gAcOH) solution was made and rocked overnight. Additionally, a 20% zein-20% PCL (g/mL) in a 2:2:2 of DCM to DMF to gAcOH solution was made and rocked overnight. To create the hydrogel layer, a 6% (83/17) poly(acrylic acid)/poly(vinyl alcohol) (PAA/PVA) (g/mL) in 1:3 deionized water to 70% ethanol solution was prepared which required sonication.3 The initial zein/PCL layer was electrospun at a rate of 0.75 mL/h, with a positive voltage from 15 - 20 kV, a negative voltage of -2 kV, a mandrel rotation of 3,000 ± 150 rpm, and a 17cm distance. The outer PAA/PVA layer was electrospun at a rate of 5.00 mL/h, with a positive voltage ranging from 16 – 20 kV, a negative voltage of -2 kV, a mandrel rotation of 3,000 ± 150 rpm, and a 17 cm distance. Crosslinking of the outer PAA/PVA layer was performed by adding 1 mL of 25% glutaraldehyde to the PAA/PVA solution before electrospinning. The hydrogel only scaffolds were placed in water to test if the amount of crosslinking was sufficient. Two-layered scaffolds were soaked in water for 10 min to test if the layers would separate. Light microscopy was performed to visualize each distinct layer. Finally, water contact angle was conducted to determine the hydrophilicity (n=3/scaffold group).

Results, Conclusions, and Discussions: Two-layered scaffold fabrication was successful, with deposition of both layers across the entire mandrel and light microscopy confirming the distinct layers. After soaking in water, the hydrogel only scaffolds were strong and easy to handle. This signifies that 1 mL of glutaraldehyde caused sufficient crosslinking. After soaking for 10 min in water, the two-layered scaffold showed no separation which provides further evidence that this method forms a congruent scaffold with distinct layers. As seen in Table 1, water contact angle measurements showed that the layered zein/PCL - PAA/PVA scaffolds were more hydrophilic than the zein/PCL scaffolds alone. Variability in deposition of the polymers across the mandrel could explain the larger standard deviations. These results suggest that cellular attachment and proliferation would be greater on the two-layered zein/PCL – PAA/PAA scaffolds than on the zein/PCL scaffolds due to the increase in hydrophilicity.

The addition of the PAA/PVA hydrogel layer did increase the hydrophilicity of the zein/PCL scaffolds. Also, water testing showed that the two-layered scaffolds did not separate, meaning the hydrogel layer could provide its hydrophilic qualities for an extended period. Two-layered zein-PCL-hydrogel scaffolds could become a new mechanism for improving the hydrophilicity of scaffolds for tissue engineering. Future work should focus on further scaffold characterization and cellular studies.

(1) Oh, S. H., & Lee, J. H. (2013). Hydrophilization of synthetic biodegradable polymer scaffolds for improved cell/tissue compatibility. Biomedical materials (Bristol, England), 8(1), 014101. https://doi.org/10.1088/1748-6041/8/1/014101
(2) Martin, A., Cai, J., Schaedel, A. L., van der Plas, M., Malmsten, M., Rades, T., & Heinz, A. (2022). Zein-polycaprolactone core-shell nanofibers for wound healing. International journal of pharmaceutics, 621, 121809. https://doi.org/10.1016/j.ijpharm.2022.121809
(3) McKeon-Fischer, K.D., Flagg, D.H. and Freeman, J.W. (2011), Coaxial electrospun poly(ε-caprolactone), multiwalled carbon nanotubes, and polyacrylic acid/polyvinyl alcohol scaffold for skeletal muscle tissue engineering. J. Biomed. Mater. Res., 99A: 493-499.

Acknowledgements (Optional):  We would like to acknowledge the Hampden-Sydney College summer undergraduate research program and the Hurt Scholar program for funding this research. Additionally, we would like to thank Mrs. Jennie Jenkins and Mr. Tony Pinchesfsky for their assistance.