Efficient extraction of a high molecular weight ulvan from stranded Ulva sp. biomass: application on the active biomembrane synthesis

Abstract

With increasing demand for biobased materials, major importance was given to the extraction and application of polysaccharides issued from renewable biomasses like algae. In this work, we investigate the feasibility of elaborating an active ulvan-based biomembrane prepared from stranded Ulva sp. biomass. Variations of extraction parameters showed that the optimal yield (13.8% w/w) was obtained using methanol under Soxhlet extraction for the defatting step and 5% (w/v) of ammonium oxalate as chelating reagent. The molecular weight (MW) was determined by gel permeation chromatography (GPC), which showed variability of MW from 201 to 1841 kDa depending on the extraction procedure. The monosaccharide composition of the obtained high MW ulvan showed the presence of rhamnose (17.61 ± 0.5%), xylose (9.22 ± 0.56%), and glucuronic acid (24.86 ± 1.29%). Purity and quality of ulvan were also assessed by FTIR and TGA analyses. The high MW ulvan fraction was thereafter used for the synthesis of a polyelectrolyte-type ulvan/chitosan biomembrane at low KCl concentration. The obtained membrane was then characterized using FTIR and XPS analyses, which evidenced that the ulvan sulfur groups were implicated in the interaction with chitosan chains. Finally, to assess the biological properties of the biomembrane, anticoagulant behavior was evaluated using APTT assay, and it has been found to significantly increase the blood clotting time in comparison with controls. This work shows the proof of concept of ulvan conversion to high added value products and, therefore, consolidates the implementation of cost-effective biorefinery approaches of green macroalgal biomass.