Poly-l-Lactic Acid Scaffolds Additivated with Rosmarinic Acid: A Multi-Analytical Approach to Assess The Morphology, Thermal Behavior, and Hydrophilicity

Abstract

This study aims to demonstrate the possibility of incorporating a natural antioxidant biomolecule into polymeric porous scaffolds. To this end, Poly-l-Lactic Acid (PLLA) scaffolds were produced using the Thermally Induced Phase Separation (TIPS) technique and additivated with different amounts of rosmarinic acid (RA). The scaffolds, with a diameter of 4 mm and a thickness of 2 mm, were characterized with a multi-analytical approach. Specifically, Scanning Electron Microscopy analyses demonstrated the presence of an interconnected porous network, characterized by a layer of RA at the level of the pore's surfaces. Moreover, the presence of RA biomolecules increased the hydrophilic nature of the sample, as evidenced by the decrease in the contact angle with water from 128° to 76°. The structure of PLLA and PLLA containing RA molecules has been investigated through DSC and XRD analyses, and the obtained results suggest that the crystallinity decreases when increasing the RA content. This approach is cost-effective, and it can be customized with different biomolecules, offering the possibility of producing porous polymeric structures containing antioxidant molecules. These scaffolds meet the requirements of tissue engineering and could offer a potential solution to reduce inflammation associated with scaffold implantation, thus improving tissue regeneration.

Keywords: hydrophilicity; poly-l-lactic acid; rosmarinic acid; solvent casting deposition; thermally induced phase separation; three-dimensional scaffold.

Figure 1

Experiment procedure scheme.

Figure 2

Digital images of samples, right to left: PLLA, PLLA-RA 2%, and PLLA-RA4%.

Figure 3

SEM images: (a–c) porous structure analysis of PLLA, PLLA-RA 2%, PLLA-RA at 600×; (d–f) porous structure analysis of PLLA, PLLA-RA 2%, PLLA-RA at 1200×; (g–i) porous structure analysis of PLLA-RA 4% at 2600×, 5000×, and 10,000×.

Figure 3

SEM images: (a–c) porous structure analysis of PLLA, PLLA-RA 2%, PLLA-RA at 600×; (d–f) porous structure analysis of PLLA, PLLA-RA 2%, PLLA-RA at 1200×; (g–i) porous structure analysis of PLLA-RA 4% at 2600×, 5000×, and 10,000×.

Figure 4

ATR-FIIR spectra: (a) RA powder and on top surfaces of PLLA, PLLA-RA 2%, PLLA-RA 4%; (b) RA powder and on bottom surfaces of PLLA, PLLA-RA 2%, PLLA-RA 4%; (c) PLLA and PLLA-RA 4%.

Figure 4

ATR-FIIR spectra: (a) RA powder and on top surfaces of PLLA, PLLA-RA 2%, PLLA-RA 4%; (b) RA powder and on bottom surfaces of PLLA, PLLA-RA 2%, PLLA-RA 4%; (c) PLLA and PLLA-RA 4%.

Figure 5

XRD trace of (a) PLLA and RA samples, and (b) PLLA, PLLA-RA 2%, PLLA-RA 4%.

Figure 5

XRD trace of (a) PLLA and RA samples, and (b) PLLA, PLLA-RA 2%, PLLA-RA 4%.

Figure 6

Thermograms of Differential Scanning Calorimetry (DSC) analysis: (a) first heating of RA powder and RA-SC; (b) second heating of RA powder and RA-SC; (c) first heating of PLLA, PLLA-RA 2%, PLLA-RA 4%, and RA-SC; (d) second heating of PLLA, PLLA-RA 2%, PLLA-RA 4%, and RA-SC.

Figure 6

Thermograms of Differential Scanning Calorimetry (DSC) analysis: (a) first heating of RA powder and RA-SC; (b) second heating of RA powder and RA-SC; (c) first heating of PLLA, PLLA-RA 2%, PLLA-RA 4%, and RA-SC; (d) second heating of PLLA, PLLA-RA 2%, PLLA-RA 4%, and RA-SC.

Figure 7

Water contact angle (WCA) image of (a) PLLA; (b) PLLA-RA 2%; (c) PLLA-RA 4%.