Abstract
Gelatin Type A (GA) and sodium alginate (SA) complexes were explored to encapsulate epidermal growth factor (EGF), and thereby to circumvent its proteolytic degradation upon topical application to chronic wounds. Phase diagrams were constructed based on turbidity as a function of GA to SA ratio and pH. Various GA-SA mixtures were compared for polydispersity index, zeta potential, Z-average, and ATR-FTIR spectra. Trypsin digestion and human dermal fibroblast scratch wound assay were done to evaluate the effects of EGF encapsulation. The onset pH values for coacervation and precipitation were closer together in high molecular weight GA (HWGA)-SA reaction mixtures than in low molecular weight GA (LWGA)-SA, which was attributed to strong H-bonding interactions between HWGA and SA probed by ATR-FTIR. EGF incorporation in both HWGA-SA precipitates and LWGA-SA coacervates below the isoelectric point of EGF, but not above it, suggests the contribution of electrostatic interactions between EGF and SA. EGF encapsulated in LWGA-SA coacervates was effectively protected from trypsin digestion and showed better in vitro scratch wound activity compared to free EGF. LWGA-SA coacervates are suggested as a novel delivery system for topical application of EGF to chronic wounds.
Highlights
Limited efficacy of topically applied growth factors to chronic wounds is in part attributed to the elevated level of proteases in the wound sites [1,2,3,4]
Complex coacervates are known for very low interfacial energy in aqueous solution, which enables the coacervate to encapsulate a variety of molecules including proteins [5]
Coacervates composed of high molecular weight Type A gelatin (HWGA) and sodium alginate (SA) showed high encapsulation efficiency for bovine serum albumin (BSA), protecting BSA from trypsin digestion
Summary
Limited efficacy of topically applied growth factors to chronic wounds is in part attributed to the elevated level of proteases in the wound sites [1,2,3,4]. For complex coacervation to occur by electrostatic interactions, the reaction pH should be adjusted so that the net charges of cationic and anionic polyelectrolytes are neutralized to form a polymer-rich liquid phase [13,15,16]. We hypothesized that the encapsulation efficiency of EGF in GA-SA coacervates would improve if we could bring the coacervation pH below the isoelectric point (pI) of EGF to derive electrostatic interactions between positively charged EGF and negatively charged SA. For selected EGF-encapsulating coacervates, trypsin digestion and human dermal fibroblast scratch wound assay were done to evaluate their potential as a novel therapeutic modality for chronic wounds such as diabetic foot ulcer
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
