Innovative membrane containing iron-based layered double hydroxide intercalated with phyto therapeutic diterpenoid

Abstract

This work developed an innovative membrane based on the high-performance PEBAX®2533 (PEBA) block copolymer and particles of iron-based layered double hydroxide (LDH) (Mg4FeAl layer composition) intercalated with phytotherapeutic abietate anions (ABI); both guest and host species are active in the promotion of wound healing. The presence of conjugated double bonds in the ABI structure promotes chemical reactions confronting its stability. Hence, LDH can protect the phytochemical species and promote its modified release. Aiming the development of wound dressings, LDH-ABI particles were immobilized in a biocompatible polymer (PEBA) by simple casting method. All samples were characterized by X-ray diffraction (XRD), vibrational (infrared and Raman) spectroscopies, thermogravimetry analysis coupled to mass spectrometry (TGA-MS), elemental chemical analyses and, in the case of polymer composites, by mechanical tests. Although the intercalation of organic anions into iron-based LDH materials is challenging, ABI intercalation was successful and using one-pot method (coprecipitation at constant pH value), according to XRD data. Additionally, spectroscopic techniques indicated the integrity of the ABI chemical structure after intercalation. The sodium abietate (NaABI) salt and the PEBA_NaABI membrane were also prepared to evaluate the effect of LDH in the formulations. In vitro release assays in saline solution at 32 °C showed the release (or solubilization) of around 3 and 5 wt./wt% of the ABI amount from LDH and salt, respectively, after 10 h. Comparatively, ABI release from the PEBA_Mg4FeAl-ABI and PEBA_NaABI formulations was improved to 20 and 22 wt%, respectively. The improvement in ABI release profiles from the membranes was related to the decrease in particles aggregation and improved media permeation. LDH particles released bioactive Mg2+ cations in the saline solution and, unlike NaABI particles, also improved the mechanical performance of the polymer. Thus, PEBA_Mg4FeAl-ABI showed promising as a component of wound dressings.