Effect of the Addition of Inorganic Fillers on the Properties of Degradable Polymeric Blends for Bone Tissue Engineering

Abstract

Bone tissue exhibits self-healing properties; however, not all defects can be repaired without surgical intervention. Bone tissue engineering offers artificial scaffolds, which can act as a temporary matrix for bone regeneration. The aim of this study was to manufacture scaffolds made of poly(lactic acid), poly(ε-caprolactone), poly(propylene fumarate), and poly(ethylene glycol) modified with bioglass, beta tricalcium phosphate (TCP), and/or wollastonite (W) particles. The scaffolds were fabricated using a gel-casting method and observed with optical and scanning electron microscopes. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetry (TG), wettability, and degradation tests were conducted. The highest content of TCP without W in the composition caused the highest hydrophilicity (water contact angle of 61.9 ± 6.3°), the fastest degradation rate (7% mass loss within 28 days), moderate ability to precipitate CaP after incubation in PBS, and no cytotoxicity for L929 cells. The highest content of W without TCP caused the highest hydrophobicity (water contact angle of 83.4 ± 1.7°), the lowest thermal stability, slower degradation (3% mass loss within 28 days), and did not evoke CaP precipitation. Moreover, some signs of cytotoxicity on day 1 were observed. The samples with both TCP and W showed moderate properties and the best cytocompatibility on day 4. Interestingly, they were covered with typical cauliflower-like hydroxyapatite deposits after incubation in phosphate-buffered saline (PBS), which might be a sign of their excellent bioactivity.

Keywords: PLA scaffolds; bone tissue engineering; composite scaffolds; polymer blends; porous scaffolds.

Figure 1

Gross morphology (A), optical microphotographs (B), and SEM microphotographs (C,D) of manufactured composite scaffolds.

Figure 2

FTIR spectra of manufactured composite scaffolds.

Figure 3

DSC curves of composite scaffolds evaluated after the first (A) and second (B) heating run.

Figure 4

TG (A) and DTG (B) curves of manufactured composite scaffolds.

Figure 5

Water contact angle of the manufactured composite scaffolds. Representative droplets are shown above each bar, where p * < 0.05, p ** < 0.01, p *** < 0.001.

Figure 6

Remaining mass of manufactured composite scaffolds as a function of the incubation time in PBS.

Figure 7

SEM microphotographs of composite scaffolds before (first panel) and after 28 days of degradation study (second and third panels; magnification 1000 and 5000×) and EDS spectra of the samples (fourth panel).

Figure 8

Metabolic activity (A) and live/dead staining (B) of L929 cells cultured in 10% extracts of composite scaffolds and in control conditions (DMEM), where p * < 0.05, p ** < 0.01, p *** < 0.001.