Advances in development of nanocomposite gels that provide localized delivery of pharmaceuticals for treatment of chronic wounds are being highly pursued. To design such materials, the use of natural polymers is recommendable due to their intrinsic biocompatibility and biodegradability. Moreover, the use of biocatalytic approaches for composite assembling is preferred compared to harsh chemical cross-linking reagents. In this study, HRP catalyzed cross-linking of hydrogels from aqueous solution of thiolated chitosan to in situ incorporated sonochemically synthesized epigallocatechin gallate nanospheres (EGCG NSs). The potential of the generated NSs for chronic wound treatment was evaluated by assessing their antibacterial properties and inhibitory effect on myeloperoxidase and collagenasemajor enzymes of inflamed chronic wounds. The EGCG NSs displayed better antibacterial and antienzymatic properties compared to the EGCG in solution. Also, the NSs were incorporated into hydrogels without affecting their integrity and were released intact in a sustained manner (during 6 days). The cytotoxicity assay confirmed the compatibility of the hybrid material with human fibroblasts that suffered less than 10% decrease in viability during 24 h. Release of functional phenolic NSs and good compatibility of the composite hydrogel with cells suggested its potential application in chronic wound management.
This work is about the synthesis of hybrid nanocomposite hydrogels comprising a thiolated chitosan platform that incorporates epigallocatechin gallate nanospheres as active polyphenolic agents for wound healing applications. The phenolic nanospheres were prepared using an industry-attractive, low-cost and fast sonochemical technology, whereas the gel formation was achieved via a green approach involving the enzymatic cross-linking with horseradish peroxidase, avoiding the use of harsh chemical cross-linkers. The superior functional properties of the phenolic nanospheres compared to their molecular counterparts are demonstrated by better attenuation of the chronicity factors found in non-healing wounds. Release of the intact and functional phenolic nanospheres coupled to good biocompatibility of the system during several days, reveals potential of this hybrid material as a dressing with prolonged activity for chronic wound management.
G-protein-coupled receptors are integral membrane proteins which constitute the largest family of signal transduction molecules participating in the majority of normal physiological processes. G-protein-coupled receptors are responsible for the control of enzyme activity, ion channels and vesicle transport, and they respond to a wide variety of stimuli, like signals involved in sensory systems such as vision, taste and olfaction, but also to a diverse set of chemical signals such as lipids, hormones, neurotransmitters, amino acids, nucleotides, peptides and proteins. This family of receptors is being widely studied because of its potential use as pharmacological targets in drug development, and recently also for its potential use in the development of novel biosensors. G-protein-coupled receptors are specifically designed to fold and function in a lipid bilayer environment, where these membrane proteins are remarkably stable and achieve their optimal performance. The currently used technology for the purification of G-protein-coupled receptors consists in their extraction from the cell membrane and solubilization into detergent micelles. A common drawback of this strategy is that G-protein-coupled receptors solubilized in typical detergents show rather poor conformational stability, which may result in relatively rapid inactivation. The poor stability of detergent-solubilized samples renders many membrane proteins biochemically intractable. This precludes the determination of a high-resolution structure and imposes severe limitations for the development of applications. Thus, the enhancement of the stability of G-protein-coupled receptors is a major issue in order to facilitate structural determination and to unravel their potential in biotechnological applications. This work provides a brief overview of some current advances in the experimental methods for stabilizing G-protein-coupled receptors that can also be extended to other types of membrane proteins.