Synthesis and characterization of cryogel structures for isolation of EPSs from Botryococcus braunii

• PHEMA-ConA cryogel was synthesized to isolate EPSs from B. braunii culture media.
• The maximum EPS adsorption capacity was found as 3.26 mg EPS/g cryogel.
• Corresponding to an adsorption yield of 80% in one-step cryogel application.
• Which can be applied to other biomasses rich in terms of exopolysaccharides.

In this study, the objective was to separate exopolysaccharides (EPSs) released in the broth subsequent to outdoor cultivation of Botryococcus braunii. For this, poly(2-hydroxyethyl methacrylate) (PHEMA) cryogels were synthesized. After that, the surface was modified by coupling Concanavalin A. Box-Behnken statistical design was used to evaluate the effect of freezing temperature, Con A concentration and flow rate on Con A binding capacity. Optimum synthesis conditions were elicited as −14.48 °C freezing temperature, 1.00 mg/ml Con A concentration and 0.30 ml/min flow rate yielding 3.18 mg Con A/g cryogel, whereas −16 °C, 1.00 mg/ml and 0.30 ml/min yielded the highest (3.38 mg) binding capacity in experimental cryogel preparation. The EPS adsorption capacity of the optimum cryogel column was found as 3.26 mg EPS/g cryogel corresponding to adsorption yield of 80%. Besides; swelling test, elemental analysis, Micro-CT, SEM and FTIR analysis were carried out for characterization of the synthesized cryogels.

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