Co-Electrospun Poly(ε-Caprolactone)/Zein Articular Cartilage Scaffolds

Abstract

Osteoarthritis scaffold-based grafts fail because of poor integration with the surrounding soft tissue and inadequate tribological properties. To circumvent this, we propose electrospun poly(ε-caprolactone)/zein-based scaffolds owing to their biomimetic capabilities. The scaffold surfaces were characterized using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, static water contact angles, and profilometry. Scaffold biocompatibility properties were assessed by measuring protein adsorption (Bicinchoninic Acid Assay), cell spreading (stained F-actin), and metabolic activity (PrestoBlue™ Cell Viability Reagent) of primary bovine chondrocytes. The data show that zein surface segregation in the membranes not only completely changed the hydrophobic behavior of the materials, but also increased the cell yield and metabolic activity on the scaffolds. The surface segregation is verified by the infrared peak at 1658 cm^-1, along with the presence and increase in N1 content in the survey XPS. This observation could explain the decrease in the water contact angles from 125° to approximately 60° in zein-comprised materials and the decrease in the protein adsorption of both bovine serum albumin and synovial fluid by half. Surface nano roughness in the PCL/zein samples additionally benefited the radial spreading of bovine chondrocytes. This study showed that co-electrospun PCL/zein scaffolds have promising surface and biocompatibility properties for use in articular-tissue-engineering applications.

Keywords: PCL; cartilage tissue engineering; chondrocytes; electrospinning; zein.

Figure 1

Nanofiber morphology of PCL/zein electrospun mats prepared from a 70/30 vol./vol. FA/AA conditions from Table 1. Average fiber diameter (n = 50 measurements) reported in nanometers.

Figure 2

C1s and O1s X-ray photoelectron spectra of the electrospun PCL, 8P40Z (H), and 6P50Z (B) samples. Peak label information in Table 2.

Figure 3

FTIR−ATR performed on the electrospun samples (PCL, 8P40Z, 6P50Z) prepared from a 70/30 v/v FA/AA solution.

Figure 4

Static Water Contact Angles (t = 0 s) performed on the PCL/zein electrospun surfaces.

Figure 5

Images obtained with the PluNeox Profilometer at 20× magnification lens analyzed using Gwyddion 2.0.

Figure 6

Protein adsorption on PCL, 8P40Z, or 6P50Z scaffold specimen measured using indirect BCA assay. (A) Adsorption of BSA and (B) adsorption of synovial fluid proteins to scaffold specimen (sample size 5). Statistically significant differences between groups are indicated by * where p ≤ 0.5, ** where p ≤ 0.01, and *** where p ≤ 0.001.

Figure 7

20× magnification laser scanning confocal microscopy of PCL, 8P40Z, and 6P50Z seeded with P1 bovine chondrocytes at days 7 and 14, stained with DAPI (blue) and Alexa Fluor 568 Phalloidin (red). Scale bars: 50 µm.