Hydrophobization of hydrophilic alginate/chitosan PEC surfaces

Abstract

Alginate and chitosan are biocompatible polysaccharides that are often combined as polyelectrolyte complexes (PECs) for the development of biomaterials. These PECs are interesting as wound dressings, among other uses. The properties of such devices depend on their surface characteristics, however. Herein we propose a method to hydrophobize highly hydrophilic alginate/chitosan PECs by initial chemical grafting of polycaprolactone (PCL) or polylactic acid, using hexane diamine or ethylenediamine as linkers, followed by a drop casting covering step. This resulted in increased adhesion between the hydrophobic layer and the PEC, when compared to direct casting. The materials obtained were evaluated as potential biomaterials by analyzing the hydrophilic properties of their surface, swelling, enzymatic degradation, and impermeability. The results revealed that hydrophobization was effective but decreased the swelling abilities of PECs, which still remained interesting (~1000%) for wound dressing applications. However, the PCL layer was not resistant to the enzymatic environment, while PLA showed impermeabilization of the PECs.

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“…CS is soluble in acids such as nitric, hydrochloric, formic, acetic, and citric acid solutions but insoluble in organic solvents, and aqueous bases without stirring. [11][12][13] CS is cationic due to the presence of reactive functional groups, and it has a significant positive charge due to the presence of a large amino group. It is also a biodegradable, antibacterial, fungistatic, safe and nontoxic polymer and is used in the medical and food industries.…”

“…It stands out among the other biopolymers thanks to its unique and fascinating features. CS is soluble in acids such as nitric, hydrochloric, formic, acetic, and citric acid solutions but insoluble in organic solvents, and aqueous bases without stirring 11–13 . CS is cationic due to the presence of reactive functional groups, and it has a significant positive charge due to the presence of a large amino group.…”