Soy Protein Isolate Gel Subjected to Freezing Treatment: Influence of Methylcellulose and Sodium Hexametaphosphate on Gel Stability, Texture and Structure

Freezing affects texture and induces the loss of gel quality. This study investigated the effects of methylcellulose (MC) (0.2%, 0.4%, 0.6%) and sodium hexametaphosphate (SHMP) (0.15%, 0.3%) on the gel textural and structural properties of SPI gels before and after freezing, and explores the synergistic enhancement of gel texture and the underlying mechanisms resulting from the simultaneous addition of SHMP and MC to SPI gels. It was revealed that MC improved the strength of SPI gels through its thickening properties, but it could not inhibit the reduction of SPI gels after freezing. The 0.4% MC-SPI gel exhibited the best gel strength (193.2 ± 2.4 g). SHMP inhibited gel reduction during freezing through hydrogen bonding and ionic interactions; it enhanced the freezing stability of SPI gels. The addition of 0.15% SHMP made the water-holding capacity in SPI gels reach the highest score after freezing (58.2 ± 0.32%). The synergistic effect of MC and SHMP could improve the strength and the freezing stability of SPI gels. MC facilitated the release of ionizable groups within SPI, causing negatively charged SHMP groups to aggregate on the SPI and inhibit the freezing aggregation of proteins. These results provide a strong basis for the improvement of cryogenic soy protein gel performance by SHMP and MC.

Design and Assessment of Biodegradable Macroporous Cryogels as Advanced Tissue Engineering and Drug Carrying Materials

Cryogels obtained by the cryotropic gelation process are macroporous hydrogels with a well-developed system of interconnected pores and shape memory. There have been significant recent advancements in our understanding of the cryotropic gelation process, and in the relationship between components, their structure and the application of the cryogels obtained. As cryogels are one of the most promising hydrogel-based biomaterials, and this field has been advancing rapidly, this review focuses on the design of biodegradable cryogels as advanced biomaterials for drug delivery and tissue engineering. The selection of a biodegradable polymer is key to the development of modern biomaterials that mimic the biological environment and the properties of artificial tissue, and are at the same time capable of being safely degraded/metabolized without any side effects. The range of biodegradable polymers utilized for cryogel formation is overviewed, including biopolymers, synthetic polymers, polymer blends, and composites. The paper discusses a cryotropic gelation method as a tool for synthesis of hydrogel materials with large, interconnected pores and mechanical, physical, chemical and biological properties, adapted for targeted biomedical applications. The effect of the composition, cross-linker, freezing conditions, and the nature of the polymer on the morphology, mechanical properties and biodegradation of cryogels is discussed. The biodegradation of cryogels and its dependence on their production and composition is overviewed. Selected representative biomedical applications demonstrate how cryogel-based materials have been used in drug delivery, tissue engineering, regenerative medicine, cancer research, and sensing.

Cryotropic gel-forming capacity of alfalfa (Medicago sativa L.) and fenugreek (Trigonella foenum graecum) seed galactomannans

Cryotropic gelation is one of the most common approaches to design novel hydrogels with multifaceted technological and biological functionalities. In the present paper, we studied the ability of highly galactosyl-substituted galactomannans, i.e. fenugreek and alfalfa gum, to form physically crosslinked hydrogels via cryogenic processing. Cycling of the galactomannan solutions (0.25 to 4% wt) from 25 to -20 to 25 °C induced the physical crosslinking of the galactomannan chains leading to the formation of different cryogel structures, i.e. filamentous aggregates (c* < c < 1%), cellular-like gel networks (1 ≤ c < 4%) or a homogeneously swollen gel (c ≥ 4%), depending on the total biopolymer content. Alfalfa gum-based cryogels exhibited higher elasticity and stiffness, better uniformity of the structure and a lower macropore size than their fenugreek counterparts. The physical blending of alfalfa or fenugreek gum with locust bean gum (2% total biopolymer) led to the reinforcement of the mechanical properties of the cryogels without significantly altering their microstructural aspects.

Cryostructuring of Polymeric Systems. 55. Retrospective View on the More than 40 Years of Studies Performed in the A.N.Nesmeyanov Institute of Organoelement Compounds with Respect of the Cryostructuring Processes in Polymeric Systems

The processes of cryostructuring in polymeric systems, the techniques of the preparation of diverse cryogels and cryostructurates, the physico-chemical mechanisms of their formation, and the applied potential of these advanced polymer materials are all of high scientific and practical interest in many countries. This review article describes and discusses the results of more than 40 years of studies in this field performed by the researchers from the A.N.Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences-one of the key centers, where such investigations are carried out. The review includes brief historical information, the description of the main effects and trends characteristic of the cryostructuring processes, the data on the morphological specifics inherent in the polymeric cryogels and cryostructurates, and examples of their implementation for solving certain applied tasks.

Protein-Polysaccharide Composite Materials: Fabrication and Applications

Protein-polysaccharide composites have been known to show a wide range of applications in biomedical and green chemical fields. These composites have been fabricated into a variety of forms, such as films, fibers, particles, and gels, dependent upon their specific applications. Post treatments of these composites, such as enhancing chemical and physical changes, have been shown to favorably alter their structure and properties, allowing for specificity of medical treatments. Protein-polysaccharide composite materials introduce many opportunities to improve biological functions and contemporary technological functions. Current applications involving the replication of artificial tissues in tissue regeneration, wound therapy, effective drug delivery systems, and food colloids have benefited from protein-polysaccharide composite materials. Although there is limited research on the development of protein-polysaccharide composites, studies have proven their effectiveness and advantages amongst multiple fields. This review aims to provide insight on the elements of protein-polysaccharide complexes, how they are formed, and how they can be applied in modern material science and engineering.

Biomaterials of PVA and PVP in medical and pharmaceutical applications: Perspectives and challenges

Poly(vinyl alcohol) (PVA) has attracted considerable research interest and is recognized among the largest volume of synthetic polymers that have been produced worldwide for almost one century. This is due to its exceptional properties which dictated its extensive use in a wide variety of applications, especially in medical and pharmaceutical fields. However, studies revealed that PVA-based biomaterials present some limitations that can restrict their use or performances. To overcome these limitations, various methods have been reported, among which blending with poly(vinylpyrrolidone) (PVP) showed promising results. Thus, our aim was to offer a systematic overview on the current state concerning the preparation, properties and various applications of biomaterials based on synergistic effect of mixtures between PVA and PVP. Future trends towards where the biomaterials research is headed were discussed, showing the promising opportunities that PVA and PVP can offer.

Cryostructuring of Polymeric Systems. 50.† Cryogels and Cryotropic Gel-Formation: Terms and Definitions

A variety of cryogenically-structured polymeric materials are of significant scientific and applied interest in various areas. However, in spite of considerable attention to these materials and intensive elaboration of their new examples, as well as the impressive growth in the number of the publications and patents on this topic over the past two decades, a marked variability of the used terminology and definitions is frequently met with in the papers, reviews, theses, patents, conference presentations, advertising materials and so forth. Therefore, the aim of this brief communication is to specify the basic terms and definitions in the particular field of macromolecular science.

Cryogels with affinity ligands as tools in protein purification

Affinity chromatography is one of the well-known separation techniques especially if high purity is desired. Introducing ligands on monolithic structure gives the possibility for purifying complex media such as plasma and crude extract. This chapter is focusing on the preparation of cryogels as monolithic column and immobilization of concanavalin A on its surface as ligand for capturing the glycoprotein horseradish peroxidase.

Biopolymer-based hydrogels as scaffolds for tissue engineering applications: a review

Hydrogels are physically or chemically cross-linked polymer networks that are able to absorb large amounts of water. They can be classified into different categories depending on various parameters including the preparation method, the charge, and the mechanical and structural characteristics. The present review aims to give an overview of hydrogels based on natural polymers and their various applications in the field of tissue engineering. In a first part, relevant parameters describing different hydrogel properties and the strategies applied to finetune these characteristics will be described. In a second part, an important class of biopolymers that possess thermosensitive properties (UCST or LCST behavior) will be discussed. Another part of the review will be devoted to the application of cryogels. Finally, the most relevant biopolymer-based hydrogel systems, the different methods of preparation, as well as an in depth overview of the applications in the field of tissue engineering will be given.

Effect of Cryogenic Treatment on the Rheological Properties of Gelatin Hydrogels

Gelatin has the ability to form a gel when cooled below the sol—gel temperature. In this study, the effects of various cryo-parameters, including the number of freeze—thaw cycles, cooling rate, thawing rate, and gelatin concentration, on the material properties were examined. The rheological properties of the cryogels improved with increasing cryo-cycles and decreasing cooling and thawing rates as well as were superior to those of the corresponding hydrogels formed at room temperature. In addition, the critical gelation concentration decreased after repeated cryo-treatments. Methacrylamide-modified gelatin was also treated cryogenically, followed by in situ UV irradiation to enable radical cross-linking. The cross-linking efficiency of specific gelatin concentrations improved with freeze—thawing. Cryogelation can be used to fine-tune the mechanical properties of hydrogels. This is of relevance to tissue engineering where porous gelatin hydrogels are used as biomaterials.

The effect of beta-glucan on the glycemic and insulin index

OBJECTIVE

To determine the effects of oat products with increasing beta-glucan content on the glycemic (GI) and insulin indexes (II) of oat products, and to establish the effect of physical properties of beta-glucan on these physiological responses.

DESIGN

Test group (n=10) randomly attended to three glucose tolerance tests and glycemic response tests for four oat bran products.

SETTINGS

Functional Foods Forum and the Department of Food Chemistry, University of Turku, and the Department of Food Technology, University of Helsinki.

SUBJECTS

One male and nine female volunteers were recruited from university students and staff, and all completed the study.

INTERVENTIONS

GI and II of different products were calculated for each subject using the average of parallel glucose tolerance tests and the subsequent glycemic/insulinemic responses for each product. Average indexes for products were calculated according to the individual data.

RESULTS

The glycemic responses to oat products with increasing amounts of beta-glucan had lower peak values than the reference glucose load. The amount of extractable beta-glucan had a high correlation between the glycemic and insulinemic response.

CONCLUSION

In addition to the total amount of beta-glucan in oat products, the amount of extractable beta-glucan in oat products explains the magnitude of the decrease in glycemic responses to carbohydrate products.