Layer-by-layer assembly of polymer-enzyme membranes for α-glucosyltransferase immobilization

• 1、School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China

Abstract：Layer-by-layer self-assembly membrane for enzyme immobilization was fabricated through electrostatic interaction between poly dimethyl diallyl ammonium chloride (PDDA) and α-glucosyltransferase (αG). Firstly, the positively charged PDDA was assembled on the negative charged sulfonated poly(ether sulfone) (SPES) support membrane to get the first layer. Then, the negatively charged αG enzyme was assembled on the first PDDA layer to obtain SPES-PDDA-αG membrane. Finally, the SPES-PDDA-αG membrane was either crosslinked by glutaraldehyde (GA) or assembled by another layer of PDDA to obtain the SPES-PDDA-αG-GA membrane or SPES-PDDA-αG-PDDA membrane, respectively. The activity and stability of the immobilized enzyme were investigated. The enzyme immobilized at the outer layer exhibited higher activity than that immobilized between PDDA layers. The preparation conditions including the sulfonation degree of SPES support, immobilization time and enzyme concentration were optimized. The maximum enzyme loading capacity was obtained at the following conditions, SPES with a sulfonation degree of 28.6%, enzyme concentration of 1.5 mg/ml and immobilization time of 16 h. The stability of immobilized enzyme was remarkably improved. Especially for SPES-PDDA-αG-GA membrane, 68% relative activity was retained at harsh condition (80oC, pH 7.0) and after storage for 40 days, 90% relative activity was retained compared with the initial activity.

Keywords： enzyme immobilization layer-by-layer assembly enzymatic membrane enzyme activity stability