Pullulan/Poly(vinyl alcohol) Hydrogels Loaded with Calendula officinalis Extract: Design and In Vitro Evaluation for Wound Healing Applications

Abstract

The therapeutic efficiency of plant extracts has been limited by their poor pharmaceutical availability. Hydrogels have promising potential to be applied as wound dressings due to their high capacity to absorb exudates and their enhanced performance in loading and releasing plant extracts. In this work, pullulan/poly (vinyl alcohol) (P/PVA) hydrogels were first prepared using an eco-friendly method based on both a covalent and physical cross-linking approach. Then, the hydrogels were loaded with the hydroalcoholic extract of Calendula officinalis by a simple post-loading immersion method. Different loading capacities were investigated in terms of the physico-chemical properties, chemical composition, mechanical properties, and water absorption. The hydrogels exhibited high loading efficiency due to the hydrogen bonding interactions between polymer and extract. The water retention capacity as well as the mechanical properties decreased with the increase in the extract amount in hydrogel. However, higher amounts of extract in the hydrogel improved the bioadhesiveness. The release of extract from hydrogels was controlled by the Fickian diffusion mechanism. Extract-loaded hydrogels expressed high antioxidant activity, reaching 70% DPPH radical scavenging after 15 min immersion in buffer solution at pH 5.5. Additionally, loaded hydrogels showed a high antibacterial activity against Gram-positive and Gram-negative bacteria and were non-cytotoxic against HDFa cells.

Chitosan–Oxidized Pullulan Hydrogels Loaded with Essential Clove Oil: Synthesis, Characterization, Antioxidant and Antimicrobial Properties

“…Moreover, due to the low diffusion in solid media, the hydrogels with high antimicrobial activity (high CO content) cannot prevent the growth of bacteria. Our results are comparable to previously reported studies [82,83].…”

“…The in vitro release of CO from the hydrogels was carried out in PBS solution (pH 5.5) at 32 • C in order to simulate physiological dermal conditions by immersing 50 mg of the CO-loaded hydrogels in 4 mL of the release medium without stirring. At predetermined time intervals, 3 mL of the solution was withdrawn and the same volume of fresh buffer was added [57,82]. The amount of CO released was calculated from the UV absorbance peak at 280 nm using the same UV-vis spectrophotometer.…”

Plant-Based Films and Hydrogels for Wound Healing

“…Another important characteristic of a wound dressing is its biocompatibility. Several studies [ 97 , 98 , 103 , 106 , 108 , 109 , 110 ] demonstrated that HGs incorporated with PEs and EOs are biocompatible with minimal or no cytotoxicity. These formulations are also able to maintain fibroblast viability [ 101 , 104 , 106 ], while inducing their migration [ 97 , 109 , 110 ] and proliferation [ 101 , 104 , 106 ].…”

Unraveling the New Perspectives on Antimicrobial Hydrogels: State-of-the-Art and Translational Applications

“…It is worth it to mention that the ethanolic extracts decrease the consistency, firmness, and adhesiveness of the hydrogel [ 102 ]. Synthetic PVA hydrogels have also been tested by loading them with Calendula officinalis extract, which improves the adhesiveness and was effective against both Gram-positive and Gram-negative bacteria [ 103 ]. Curcumin, obtained from the roots of Curcuma longa, is a hydrophobic polyphenolic compound with remarkable bioactive properties, and promising results have been obtained by loading it into chitosan or PVA hydrogels [ 104 , 105 , 106 , 107 ].…”