Development of Polyphenol-Functionalized Gelatin-Poly(vinylpyrrolidone) IPN for Potential Biomedical Applications

Abstract

Owing to their suitable physical and chemical properties, hydrogels have been considered a convenient choice for wound dressings because of the advantages that they offer, such as maintaining the moist environment required for wound healing. In this research, interpenetrating hydrogels of polyphenol-functionalized gelatin (GE), a water-soluble protein derived from natural polymer collagen with excellent biocompatibility, no immunogenicity, and hydrophilicity, and polyvinylpyrrolidone (PVP), a hydrophilic, non-toxic, biodegradable, biocompatible polymer that is soluble in many solvents, widely used in biomedical applications, particularly as a basic material for the manufacturing of hydrogel wound dressings, were synthesized. Gallic acid (GA) was selected in this work to study whether the interpenetrating polymer networks (IPNs) synthesized can provide antioxidant properties given that this material is intended to be used as a potential wound dressing. The obtained IPN hydrogels showed improved mechanical properties in comparison with pristine gelatin network (net-GE), a porous structure, and good thermal stability for biological applications. The antioxidant capacity of the IPNs functionalized with GA was compared to Trolox standards, obtaining a radical scavenging activity (RSA%) equivalent to a Trolox concentration of 400 µM.

Keywords: antioxidant; gelatin; hydrogel; interpenetrating network; poly(vinylpyrrolidone); radiation crosslinking.

Figure 1

Scheme of the synthesis route to obtain GA-functionalized IPN hydrogels.

Figure 2

FTIR-ATR stacked spectra.

Figure 3

TGA thermograms under N₂ of net-GE, PVP, and IPN net-GE/PVP.

Figure 4

SEM micrographs of cross-section morphology of hydrogels after lyophilization. (a) net-GE, (b) net-GE/PVP IPN (10% NVP solution), and (c) net-GE/PVP IPN (15% NVP solution). Magnification: 1000×. Scale bar: 50 µm.

Figure 5

Swelling of net-GE synthesized with different GE concentrations: (a) 5% and (b) 10% in distilled water at room temperature (c).

Figure 6

Stiffness of GE-based hydrogels. Young’s modulus was measured using a microindentation test and by fitting the Hertz model to the force–distance curves. A one-way analysis of variance (ANOVA) with Tukey correction was employed for multiple comparisons. It was considered statistically significant when p < 0.05; *** p < 0.0001.

Figure 7

(a) Calibration curve of gallic acid; (b) calibration curve of Trolox.

Figure 8

Comparation of radical scavenging activity (RSA%) of net-GE/PVP IPN and net-GE hydrogels functionalized with GA. net-GE was used as a control. A one-way analysis of variance (ANOVA) with Tukey correction was employed for multiple comparisons. It was considered statistically significant when p < 0.05; *** p < 0.0001.