Formulation and characterization of gellan–DEAE-dextran polyelectrolyte complex hydrogels

Background: There is a need to formulate hydrogels via direct physical interaction to circumvent the use of crosslinker which can affect the integrity of the entrapped drug in the hydrogel.

Objective: The aim of this study is to formulate and characterise plain polyelectrolyte complex (PEC) hydrogels prepared by physical interaction between gellan gum and oppositely charged DEAE-Dextran.

Method: Gellan-DEAE-Dextran (GDD) PEC hydrogels were prepared by polyelectrolyte complexation of gellan and DEAE-Dextran. The GDD-PEC hydrogels were characterized using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). Their swelling kinetics and rheological properties were also evaluated.

Results: Morphological characteristics analysed by SEM of plain gellan (G) hydrogel showed strand-like smooth compact structured surface while the GDD-PEC hydrogels exhibited crinkled rough surfaces. The shifts and disappearances in peaks shown in the FTIR spectra, suggested an interaction between gellan and DEAEDextran. DSC showed that the gellan and DEAE-Dextran merged into a single endothermic melting peak between 99.8 and 115.3 °C in the GDD-PEC hydrogels. Their TGA showed that the plain gellan (G) hydrogel was able to withstand more heat when compared to the GDD-PEC hydrogels. The GDD-PEC hydrogels exhibited pseudoplastic and elastic characteristics based on the concentration of DEAE-Dextran. The addition of DEAEDextran to GDD-PEC hydrogels significantly increased (p < 0.05, n = 4) their swelling ratio when compared to the plain gellan (G) hydrogel.

Conclusion: GDD-PEC hydrogels were successfully formulated and characterised. This formulation has the potential for use in transdermal drug delivery systems.