Mechanical behavior of cold‐water fish gelatin gels crosslinked with 1,4‐butanediol diglycidyl ether

Swim bladder-derived biomaterials: structures, compositions, properties, modifications, and biomedical applications

Animal-derived biomaterials have been extensively employed in clinical practice owing to their compositional and structural similarities with those of human tissues and organs, exhibiting good mechanical properties and biocompatibility, and extensive sources. However, there is an associated risk of infection with pathogenic microorganisms after the implantation of tissues from pigs, cattle, and other mammals in humans. Therefore, researchers have begun to explore the development of non-mammalian regenerative biomaterials. Among these is the swim bladder, a fish-derived biomaterial that is rapidly used in various fields of biomedicine because of its high collagen, elastin, and polysaccharide content. However, relevant reviews on the biomedical applications of swim bladders as effective biomaterials are lacking. Therefore, based on our previous research and in-depth understanding of this field, this review describes the structures and compositions, properties, and modifications of the swim bladder, with their direct (including soft tissue repair, dural repair, cardiovascular repair, and edible and pharmaceutical fish maw) and indirect applications (including extracted collagen peptides with smaller molecular weights, and collagen or gelatin with higher molecular weights used for hydrogels, and biological adhesives or glues) in the field of biomedicine in recent years. This review provides insights into the use of swim bladders as source of biomaterial; hence, it can aid biomedicine scholars by providing directions for advancements in this field.

Water-Insoluble, Thermostable, Crosslinked Gelatin Matrix for Soft Tissue Implant Development

In this present study, the material science background of crosslinked gelatin (GEL) was investigated. The aim was to assess the optimal reaction parameters for the production of a water-insoluble crosslinked gelatin matrix suitable for heat sterilization. Matrices were subjected to enzymatic degradation assessments, and their ability to withstand heat sterilization was evaluated. The impact of different crosslinkers on matrix properties was analyzed. It was found that matrices crosslinked with butanediol diglycidyl ether (BDDE) and poly(ethylene glycol) diglycidyl ether (PEGDE) were resistant to enzymatic degradation and heat sterilization. Additionally, at 1 v/v % crosslinker concentration, the crosslinked weight was lower than the starting weight, suggesting simultaneous degradation and crosslinking. The crosslinked weight and swelling ratio were optimal in the case of the matrices that were crosslinked with 3% and 5% v/v BDDE and PEGDE. FTIR analysis confirmed crosslinking, and the reduction of free primary amino groups indicated effective crosslinking even at a 1% v/v crosslinker concentration. Moreover, stress-strain and compression characteristics of the 5% v/v BDDE crosslinked matrix were comparable to native gelatin. Based on material science measurements, the crosslinked matrices may be promising candidates for scaffold development, including properties such as resistance to enzymatic degradation and heat sterilization.

Effects of acetic, malic, and citric acids on the large deformation behaviors of fish gelatin gels

This research was aimed to quantify the effects of acetic acid, malic acid, and citric acid (0, 0.5, 1.0, and 2.0 g/100 g H2 O) on the stress-strain responses of fish gelatin (FG) gels (2, 4, and 6.67 g/100 g H2 O) under uniaxial compression up to 68% of deformation. The first-order Ogden model fitted quite well for the compression responses of FG gels (R2  = 0.9909-0.9997). Protons from the acids played a key role on weakening the FG gel structures (gel rigidity, μ, decreased 11%-27%), as the μ values and pH values of FG gels were linearly correlated (R2  = 0.8240-0.9748), regardless of the acid type. The addition of an acid also resulted in a significant increase (p < .002) in the strain hardening capacity (α) of gels with 2 g FG/100 g H2 O. Both μ and α values of FG gels with higher gelatin concentrations were less affected by an acid partly due to their stronger buffering effects. The μ and α values of FG gels as affected by acids could not be fully explained based upon the pH changes, implying that the effects of acetate, malate, and citrate ions on the gel structure could not be ignored.