Chitosan Graft Copolymers with N-Vinylimidazole as Promising Matrices for Immobilization of Bromelain, Ficin, and Papain

Abstract

This work aims to synthesize graft copolymers of chitosan and N-vinylimidazole (VI) with different compositions to be used as matrices for the immobilization of cysteine proteases—bromelain, ficin, and papain. The copolymers are synthesized by free radical solution copolymerization with a potassium persulfate-sodium metabisulfite blend initiator. The copolymers have a relatively high frequency of grafting and yields. All the synthesized graft copolymers are water-soluble, and their solutions are characterized by DLS and laser Doppler microelectrophoresis. The copolymers are self-assembled in aqueous solutions, and they have a cationic nature and pH-sensitivity correlating to the VI content. The FTIR data demonstrate that synthesized graft copolymers conjugate cysteine proteases. The synthesized copolymer adsorbs more enzyme macromolecules compared to non-modified chitosan with the same molecular weight. The proteolytic activity of the immobilized enzymes is increased up to 100% compared to native ones. The immobilized ficin retains up to 97% of the initial activity after a one-day incubation, the immobilized bromelain retains 69% of activity after a 3-day incubation, and the immobilized papain retains 57% of the initial activity after a 7-day incubation. Therefore, the synthesized copolymers can be used as matrices for the immobilization of bromelain, ficin, and papain.

Novel Biocatalysts Based on Bromelain Immobilized on Functionalized Chitosans and Research on Their Structural Features

“…Finally, we compare the activity recovery of immobilized bromelain obtained in this work with our previously published results ( Figure 6 ). Earlier, we studied bromelain immobilization on chitosan (Ch) [ 46 ], 2-(4-acetamido-2-sulfanilamide) chitosan (SACh) [ 41 ], and chitosan copolymer with poly- N -vinylimidazole (Ch-g-PVI) [ 63 ]. As can be seen, the best activity recovery is achieved for bromelain immobilized on HTCCh and SACh, while for other proposed matrices, its value is dramatically low.…”

The Low-Waste Grafting Copolymerization Modification of Chitosan Is a Promising Approach to Obtaining Materials for Food Applications

“…The frequency of grafting, FG , is expressed as the number of grafted polymer chains per anhydrous glucosamine unit, AGU , in the backbone polymer and is obtained from the relationship [ 21 ] where PVP , % is the percentage of grafted PVP in Cht- g -PVP; M PVP is the molecular weight of PVP; M AGU is the average weight of an anhydrous glucose unit of Cht; and Cht , % is the percent of Cht in Cht- g -PVP.…”

“…The frequency of grafting, FG, is expressed as the number of grafted polymer chains per anhydrous glucosamine unit, AGU, in the backbone polymer and is obtained from the relationship [21]…”

Carboxymethyl Cellulose-Based Polymers as Promising Matrices for Ficin Immobilization

“…Moreover, it was shown that the grafting of poly( N -vinylimidazole) or poly( N , N -dimethyl amino ethyl methacrylate) (PDMAEMA) on Na-CMC macromolecules increases the loading and encapsulation efficiency of paclitaxel as compared to non-modified Na-CMC [ 12 , 13 ]. Paclitaxel is a plant-origin drug with a complex structure [ 14 ], so it can be suggested that incorporation of the side nitrogen-containing macromolecular substitutes may increase the interactions with other complex biostructures, e.g., enzymes [ 15 ].…”