Use of polyelectrolyte complex‐stabilized calcium alginate gel for entrapment of β‐amylase

Abstract

Calcium alginate gel stabilized with a polyelectrolyte complex (PEC) consisting of potassium poly(vinyl alcohol) sulfate (KPVS) and trimethylammonium glycol chitosan iodide (TGCI) was used for the immobilization of beta-amylase. The immobilization was made by gelling aqueous droplets of enzyme solution including both sodium alginate and KPVS in a CaCl(2) solution containing TGCI. The activity of the enzyme entrapped into the stabilized gel beads was evaluated by studying the batch reaction kinetics of enzyme-catalyzed hydrolysis of maltotetraose. Repeated kinetic measurements, totaling 18, were carried out at fixed time intervals. After each measurement the beads were stirred for 1 day in a freshly prepared 10 mM NaCl solution at 3 degrees C. It was found that the immobilized system remained stable without leading to a serious loss of the activity or to a large leakage of the enzyme from the support. This was explained as being due to a PEC-crosslinked contracted network structure of the stabilized gel matrix.

Polyelectrolyte complex formation between alginate and chitosan as a function of pH

“…Chitosan and alginate are well known polyelectrolytes that can be used as thickening agents in the food industry, in drug‐release systems in pharmaceutical applications,1–4 as biomaterials in wound healing5 and cell culture applications,6 or as an ion exchange material for the removal of heavy metal ions from industrial waste waters 7–10. These two polysaccharides can also be used together to form a polyelectrolyte complex, especially to encapsulate proteins, cells and enzymes 11–14. Polyelectrolyte complexes can be obtained as precipitates when cationic polymers are mixed with anionic polymers in aqueous solutions.…”

“…Mixing of solutions containing polymeric acids and polymeric bases can lead to mutual precipitation, even in extremely dilute solutions. A coulombic force is believed6, 13–15 to be the primary binding force for the formation of these complexes, the interactions taking place primarily between ionizable groups bearing opposite charges. Secondary bonding forces, like hydrogen bonding or covalent bonding, may also be important in the formation.…”

“…Recently, the use of natural polymers for encapsulation of drugs, proteins, and viable cells has received much attention because of their biocompatibility. In some applications, the polymer matrix has been coated with another polymer to control the release of encapsulated material 3, 4, 13–17. The success of the coatings is attributed in large part to the coulombic interactions between these polymers, which are polyelectrolytes.…”

“…Chitosan–alginate complex systems have been studied12–14 in the form of beads, used generally as a controlled‐release system for high‐molecular‐weight proteins or drugs. Huguet et al13 reported in 1994 that the release of encapsulated hemoglobin ( M w : 60,000), during storage of chitosan‐coated alginate beads in water, depended on the conditions of their formation and particularly on the chitosan molecular weight and the pH at which the beads were prepared.…”

Preparation of base‐amplifying microcapsules and their application to photoreactive materials

“…1) was synthesized using 2isocyanatoethyl methacrylate and 9-fluorenylmethanol, and shell polymer 2 was synthesized with 3 in a radical polymerization (M w 5 1.3 3 10 4 , M w /M n 5 1.5). The BA microcapsule consisting of 1 and 2, 1 in 2, was prepared using a liquid drying method 16,17 with a dichloromethane/water O/W emulsion system (see SI). It was found using a scanning electron microscope (SEM, Fig.…”