Enzyme encapsulation in freeze-dried bionanocomposites prepared from chitosan and xanthan gum blend

Freeze-dried hydrogel was prepared from a colloidal suspension of chitosan and xanthan gum blend in order to encapsulate an enzyme (firefly luciferase), and the release behavior of the enzyme from the prepared hydrogels was investigated. Selected amount of firefly luciferase was homogenized with the original polymer solution, and was then stabilized in the resultant freeze-dried samples. The encapsulated enzymes showed their enzymatic activities through bioluminescence reaction and in terms of encapsulation stability, prepared samples were found to be sensitive to the buffer pH, that is, the release rate of the enzyme was larger in pH 6.0 than in pH 8.0. The addition of the montmorillonite nanoclay (MMT) significantly lowered the enzyme release rate due to strong influence on the structural modification of the bionanocomposites. Small angle X-ray scattering measurements suggested that this was due to the modification of polymeric network structures, and the polymer network affected the release behavior of the enzyme. Further, enzymatic activities of the encapsulated and the released enzyme were confirmed for over 30 days, suggesting that the hydrogel formulation could be an excellent support structure for encapsulating bioactive substances such as enzymes.

► Enzyme was encapsulated in a freeze-dried hydrogel (bionanocomposite) prepared from chitosan/xanthan gum blend associated with montmorillonite nanoclay. ► Enzyme release behavior was controlled by the freeze-drying condition and the nanoclay addition. ► The polymeric network modifications were confirmed by SAXS measurement. ► Enzymatic activities were fairly well confirmed.