Immobilization of mushroom polyphenol oxidase on poly(allyl glycidyl ether-co-ethylene glycol dimethacrylate) macroporous beaded copolymers

Chemical and physical Chitosan modification for designing enzymatic industrial biocatalysts: How to choose the best strategy?

Chitosan is one of the most abundant natural polymer worldwide, and due to its inherent characteristics, its use in industrial processes has been extensively explored. Because it is biodegradable, biocompatible, non-toxic, hydrophilic, cheap, and has good physical-chemical stability, it is seen as an excellent alternative for the replacement of synthetic materials in the search for more sustainable production methodologies. Thus being, a possible biotechnological application of Chitosan is as a direct support for enzyme immobilization. However, its applicability is quite specific, and to overcome this issue, alternative pretreatments are required, such as chemical and physical modifications to its structure, enabling its use in a wider array of applications. This review aims to present the topic in detail, by exploring and discussing methods of employment of Chitosan in enzymatic immobilization processes with various enzymes, presenting its advantages and disadvantages, as well as listing possible chemical modifications and combinations with other compounds for formulating an ideal support for this purpose. First, we will present Chitosan emphasizing its characteristics that allow its use as enzyme support. Furthermore, we will discuss possible physicochemical modifications that can be made to Chitosan, mentioning the improvements obtained in each process. These discussions will enable a comprehensive comparison between, and an informed choice of, the best technologies concerning enzyme immobilization and the application conditions of the biocatalyst.

pH-sensitive sodium alginate hydrogels for riboflavin controlled release

Sodium alginate (SA) grafted with polyglycidyl methacrylate hydrogels (PGMA-g-SA) was prepared as pH sensitive drug delivery matrices for riboflavin (RF). The hydrogel copolymer matrices were compared with calcium alginate (CA) beads for swelling, degradation, entrapment efficiency and in vitro release of RF. The structure, surface morphology of the CA beads and the prepared hydrogels as well as the chemical stability of the encapsulated drug were characterized by FT-IR and SEM, respectively. The results demonstrate that the optimal formulation was achieved with PGMA-g-SA proportion of (0.75 mol/1 g) and loaded RF 0.03 g. It has been observed that the in vitro release study of RF from this formulation was superior to the other ones and was able to maintain the release for ∼3 and 4 days for the simulated intestinal fluid (SIF) and simulated gastric fluid (SGF), respectively. In general, it has been shown that, GMA grafted onto SA enhanced drug entrapment efficiency, decreased swelling and degradation behaviors of the carrier. In addition, it slowed and controlled the release of RF from the PGMA-g-SA hydrogel compared with pure SA beads crosslinked with Ca2+ ions alone, which thereby provides a facile and effective method to improve the drug delivery systems.