Thermosetting (bio)materials derived from renewable resources: A critical review

Collagen and gelatin have been widely used in the food, pharmaceutical, and cosmetic industries due to their excellent biocompatibility, easy biodegradability, and weak antigenicity. Fish collagen and gelatin are of renewed interest, owing to the safety and religious concerns of their mammalian counterparts. The structure of collagen has been studied using various modern technologies, and interpretation of the raw data should be done with caution. The structure of collagen may vary with sources and seasons, which may affect its applications and optimal extraction conditions. Numerous studies have investigated the bioactivities and biological effects of collagen, gelatin, and their hydrolysis peptides, using both in vitro and in vivo assay models. In addition to their established nutritional value as a protein source, collagen and collagen-derived products may exert various potential biological activities on cells in the extracellular matrix through the corresponding food-derived peptides after ingestion, and this might justify their applications in dietary supplements and pharmaceutical preparations. Moreover, an increasing number of novel applications have been found for collagen and gelatin. Therefore, this review covers the current understanding of the structure, bioactivities, and biological effects of collagen, gelatin, and gelatin hydrolysates as well as their most recent applications.

Collagen and gelatin.

Microencapsulation of cells by using biodegradable hydrogels offers numerous attractive features for a variety of biomedical applications including tissue engineering. This study highlights the fabrication of microcapsules from an alginate–gelatin crosslinked hydrogel (ADA–GEL) and presents the evaluation of the physico-chemical properties of the new microcapsules which are relevant for designing suitable microcapsules for tissue engineering. Alginate di-aldehyde (ADA) was synthesized by periodate oxidation of alginate which facilitates crosslinking with gelatin through Schiff's base formation between the free amino groups of gelatin and the available aldehyde groups of ADA. Formation of Schiff's base in ADA–GEL and aldehyde groups in ADA was confirmed by FTIR and NMR spectroscopy, respectively. Thermal degradation behavior of films and microcapsules fabricated from alginate, ADA and ADA–GEL was dependent on the hydrogel composition. The gelation time of ADA–GEL was found to decrease with increasing gelatin content. The swelling ratio of ADA–GEL microcapsules of all compositions was significantly decreased, whereas the degradability was found to increase with the increase of gelatin ratio. The surface morphology of the ADA–GEL microcapsules was totally different from that of alginate and ADA microcapsules, observed by SEM. Two different buffer solutions (with and without calcium salt) have an influence on the stability of microcapsules which had a significant effect on the gelatin release profile of ADA–GEL microcapsules in these two buffer solutions.

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Fabrication of alginate–gelatin crosslinked hydrogel microcapsules and evaluation of the microstructure and physico-chemical properties

Preparation and properties of dialdehyde carboxymethyl cellulose crosslinked gelatin edible films

Enhancing water repellence and mechanical properties of gelatin films by tannin addition.

Model gelatin/montmorillonite (Ge/MMt) composites were obtained for a variety of unmodified clay concentrations and in the absence of additives, with the main goal of evaluating the effect of the morphologies developed on the composites thermal stability.

Nanocomposites based on gelatin and montmorillonite

Creep behavior of glutaraldehyde-crosslinked gelatin films was evaluated by short-time flexural tests at 30 °C. Samples were characterized by the number-average molecular weight between two crosslinking points, determined by using the Flory–Renher equation. Creep response decreased with increasing degree of crosslinking, which is an indication that crosslinking improves the film stiffness. Experimental creep data were compared with calculated ones by using two different approaches, the creep power-law and the four-parameters model. Good fitting of the experimental results with both models was found, leading to a relationship between the observed creep behavior and the structure of the crosslinked gelatin films. Chemical crosslinkages seemed to induce a decrease of the viscous creep and an enhancement of the elastic contribution.

J. F. Martucci

Papers

Nanocomposites based on gelatin and montmorillonite

Creep of glutaraldehyde-crosslinked gelatin films