Iron(III) cross-linked hydrogels based on Alteromonas macleodii Mo 169 exopolysaccharide

Recently, polysaccharide-based hydrogels crosslinked with the trivalent iron cation have attracted interest due to their remarkable properties that include high mechanical stability, stimuli-responsiveness, and enhanced absorptivity. In this study, a Fe³⁺ crosslinked hydrogel was prepared using the biocompatible extracellular polysaccharide (EPS) secreted by the marine bacterium Alteromonas macleodii Mo169. Hydrogels with mechanical strengths (G') ranging from 0.3 kPa to 44.5 kPa were obtained as a result of the combination of different Fe³⁺ (0.05-9.95 g L^-1) and EPS (0.3-1.7 %) concentrations. All the hydrogels had a water content above 98 %. Three different hydrogels, named H_A, H_B, and H_C, were chosen for further characterization. With strength values (G') of 3.2, 28.9, and 44.5 kPa, respectively, these hydrogels might meet the strength requirements for several specific applications. Their mechanical resistance increased as higher Fe³⁺ and polymer concentrations were used in their preparation (the compressive hardness increased from 8.7 to 192.1 kPa for hydrogel H_A and H_C, respectively). In addition, a tighter mesh was noticed for H_C, which was correlated to its lower swelling ratio value compared to H_A and H_B. Overall, this preliminary study highlighted the potential of these hydrogels for tissue engineering, drug delivery, or wound healing applications.