Development and Characterization of Xanthan Gum and Alginate Based Bioadhesive Film for Pycnogenol Topical Use in Wound Treatment

Abstract

Pycnogenol (PYC) is a concentrate of phenolic compounds derived from French maritime pine; its biological activity as antioxidant, anti-inflammatory and antibacterial suggests its use in the treatment of open wounds. A bioadhesive film, loaded with PYC, was prepared by casting, starting with a combination of two biopolymer acqueous solutions: xanthan gum (1% wt/wt) and sodium alginate (1.5% wt/wt), in a 2.5/7.5 (wt/wt) ratio. In both solutions, glycerol (10% wt/wt) was added as plasticizing agent. The film resulted in an adhesive capable to absorb a simulated wound fluid (~ 65% wt/wt within 1 h), therefore suitable for exuding wounds. The mechanical characterization showed that the film is deformable (elastic modulus E = 3.070 ± 0.044 MPa), suggesting adaptability to any type of surface and resistance to mechanical solicitations. PYC is released within 24 h by a sustained mechanism, achieving a maximum concentration of ~ 0.2 mg/mL, that is safe for keratinocytes, as shown by cytotoxicity studies. A concentration of 0.015 mg/mL is reached in the first 5 min after application, at which point PYC stimulates keratinocyte growth. These preliminary results suggest the use of PYC in formulations designed for topical use.

Keywords: bioadhesion; hydrogel film; pycnogenol; sodium alginate; wounds; xanthan gum.

Figure 1

TGA and DTA profiles of film A and film B (n = 3).

Figure 2

Stress- strain curved of film A (red line) and film B (black line), (n = 5).

Figure 3

Micrographs of the surface for film A (A,B) and film B (D,E); thickness of film A (C) and film B (F) (n = 3).

Figure 4

Hydration capacity (A) and erosion matrix (B) of film A (blue diamonds) and film B (red squares) (n = 3); * p > 0.05.

Figure 5

Micrographs of the surface of film A-loaded (A,B) and film B-loaded (D,E) and thickness of film A-loaded (C) and film B-loaded (F) (n = 3).

Figure 6

Micrographs of the sections of film A (A,B) and film B (C); (n = 3).

Figure 7

TGA (A) and DTG (B) curves of film A-loaded and film B-loaded (n = 3).

Figure 8

Stress-strain curves of loaded films (A) and loaded and unloaded film A and B (B) (n = 5).

Figure 9

In vitro release profiles obtained from plotting concentration (A) vs film A-loaded time and % released (B) vs time (n = 3).

Figure 10

Viability measured in vitro on HaCaT cells for different PYC concentrations (0.015–1.335 mg/mL). CTR, untreated cells in DMEM were set at 100%. DMSO in three different percentages (1%, 2% and 4%) as positive controls (n = 3).

Figure 11

Pictures of scratch test performed on untreated HaCat cells (CTR) and treated with two different PYC concentrations 0.015 mg/mL and 0.030 mg/mL (n = 2).