Fabrication and biomedical applications of Arabinoxylan, Pectin, Chitosan, Soy protein, and Silk fibroin hydrogels via laccase - ferulic acid redox chemistry

The role and mechanisms of microbes in dichlorodiphenyltrichloroethane (DDT) and its residues bioremediation

Environmental contamination with dichlorodiphenyltrichloroethane (DDT) has sever effects on the ecosystem worldwide. DDT is a recalcitrant synthetic chemical with high toxicity and lipophilicity. It is also bioaccumulated in the food chain and causes genotoxic, estrogenic, carcinogenic, and mutagenic effects on aquatic organisms and humans. Microbial remediation mechanism and its enzymes are very important for removing DDT from environment. DDT and its main residues dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD) can biodegrade slowly in soil and water. To enhance this process, a number of strategies are proposed, such as bio-attenuation, biostimulation, bioaugmentation and the manipulation of environmental conditions to enhance the activity of microbial enzymes. The addition of organic matter and flooding of the soil enhance DDT degradation. Microbial candidates for DDT remediation include micro-algae, fungi and bacteria. This review provide brief information and recommendation on microbial DDT remediation and its mechanisms.

Recent advances of silk fibroin materials: From molecular modification and matrix enhancement to possible encapsulation-related functional food applications

Silk fibroin materials are emergingly explored for food applications due to their inherent properties including safe oral consumption, biocompatibility, gelatinization, antioxidant performance, and mechanical properties. However, silk fibroin possesses drawbacks like brittleness owing to its inherent specific composition and structure, which limit their applications in this field. This review discusses current progress about molecular modification methods on silk fibroin such as extraction, blending, self-assembly, enzymatic catalysis, etc., to address these limitations and improve their physical/chemical properties. It also summarizes matrix enhancement strategies including freeze drying, spray drying, electrospinning/electrospraying, microfluidic spinning/wheel spinning, desolvation and supercritical fluid, to generate nano-, submicron-, micron-, or bulk-scale materials. It finally highlights the food applications of silk fibroin materials, including nutraceutical improvement, emulsions, enzyme immobilization and 3D/4D printing. This review also provides insights on potential opportunities (like safe modification, toxicity risk evaluation, and digestion conditions) and possibilities (like digital additive manufacturing) in functional food industry.

Fabrication and characterization of soy protein isolation-ferulic acid antioxidant hydrogels

BACKGROUND

Soy protein gel products are prone to direct oxidation by reactive oxygen during processing and transportation, thus reducing their functional properties and nutritional values. A covalent complex was prepared with soy protein isolate (SPI) and ferulic acid (FA) catalyzed by laccase (LC). The complex was further treated with microbial transglutaminase (TGase) to form hydrogels. The structural changes of the covalent complex (SPI-FA) and the properties and antioxidant stability of hydrogel were investigated.

RESULTS

The SPI-FA complexes were demonstrated to be covalently bound by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and they had the least hydrophobic and free sulfhydryl groups at a 1.0 mg mL-1 FA concentration. The α-helix of complexes increased from 11.50% to 27.39%, and random coil dropped from 26.06% to 14.44%. The addition of FA caused SPI fluorescence quenching and redshift. The hydrogel was formed after the complex was induced with TGase, and its hardness and water holding capacity was increased by 50.61% and 26.21%, respectively. Scanning electron microscopy showed that a layered and ordered gel structure was formed. After in vitro digestion, the complex hydrogels maintained stable antioxidant activity, and the free radical scavenging rates of DPPH and ABTS reached 87.65% and 84.45%, respectively.

CONCLUSION

SPI-FA covalent complexes were prepared under laccase catalysis, and complex hydrogels were formed by TGase. Hydrogels have stable antioxidant activity, which provides application prospects for the antioxidant development of food. © 2023 Society of Chemical Industry.

Recent advance in modification strategies and applications of soy protein gel properties

Soy protein gel can be developed into a variety of products, ranging from traditional food (e.g., tofu) to newly developed food (e.g., soy yogurt and meat analog). So far, efforts are still needed to be made on modifying the gel properties of soy protein for improving its sensory properties as animal protein-based food substitutes. Furthermore, there is always a need to regulate its gel properties for designing novel and tailored products of soy protein gels due to the fast-growing plant protein-based product market. This review gave an emphasis on the latest modification strategies and applications of gel properties of soy protein. The modifying methods of soy protein gel properties were reviewed from an aspect of composition or processing. Compositional modification included changing protein composition and gelling conditions and using additives, whereas processing strategies can be achieved through physical, chemical, and enzymatic treatments. Several compositional modification and processing strategies have been both proven to alter the gel properties of soy protein effectively. So far, soy protein gel has been applied in the field of food and biomedicine. In the future, more mechanistic studies on the modification methods are still needed to facilitate the full application of soy protein gel.

Bacterial Biofilm Formation on Biomaterials and Approaches to Its Treatment and Prevention

Bacterial biofilms can cause widespread infection. In addition to causing urinary tract infections and pulmonary infections in patients with cystic fibrosis, biofilms can help microorganisms adhere to the surfaces of various medical devices, causing biofilm-associated infections on the surfaces of biomaterials such as venous ducts, joint prostheses, mechanical heart valves, and catheters. Biofilms provide a protective barrier for bacteria and provide resistance to antimicrobial agents, which increases the morbidity and mortality of patients. This review summarizes biofilm formation processes and resistance mechanisms, as well as the main features of clinically persistent infections caused by biofilms. Considering the various infections caused by clinical medical devices, we introduce two main methods to prevent and treat biomaterial-related biofilm infection: antibacterial coatings and the surface modification of biomaterials. Antibacterial coatings depend on the covalent immobilization of antimicrobial agents on the coating surface and drug release to prevent and combat infection, while the surface modification of biomaterials affects the adhesion behavior of cells on the surfaces of implants and the subsequent biofilm formation process by altering the physical and chemical properties of the implant material surface. The advantages of each strategy in terms of their antibacterial effect, biocompatibility, limitations, and application prospects are analyzed, providing ideas and research directions for the development of novel biofilm infection strategies related to therapeutic materials.

Characterization and In Vivo Assay of Allantoin-Enriched Pectin Hydrogel for the Treatment of Skin Wounds

This work describes a liquid allantoin-enriched pectin hydrogel with hydrophilic behavior that is supported by the presence of functional groups related to healing efficacy. A topical study shows the effect of the hydrogel application on surgically induced skin wound healing in a rat model. Contact angle measurements confirm hydrophilic behavior (11.37°), while Fourier-transform infrared spectroscopy indicates the presence of functional groups related to the healing effectiveness (carboxylic acid and amine groups). Allantoin is distributed on the surface and inside the amorphous pectin hydrogel surrounded by a heterogeneous distribution of pores. This promotes wound drying with better interaction between the hydrogel and cells involved in the wound healing process. An experimental study with female Wistar rats indicates that the hydrogel improves wound contraction, reducing around 71.43% of the total healing time and reaching total wound closure in 15 days.

Improving Effects of Laccase-Mediated Pectin–Ferulic Acid Conjugate and Transglutaminase on Active Peptide Production in Bovine Lactoferrin Digests

Bovine lactoferrin (bLf) is a multifunctional glycoprotein and a good candidate for producing diverse bioactive peptides, which are easily lost during over-digestion. Accordingly, the effects of laccase-mediated pectin–ferulic acid conjugate (PF) and transglutaminase (TG) on improving the production of bLf active peptides by in vitro gastrointestinal digestion were investigated. Using ultra-high-performance liquid chromatography tandem mass spectroscopy (UPLC-MS-MS), the digests of bLf alone, PF-encapsulated bLf complex (LfPF), and TG-treated LfPF complex (LfPFTG) produced by conditioned in vitro gastric digestion (2000 U/mL pepsin, pH 3.0, 37 °C, 2 h) were identified with seven groups of active peptide-related fragments, including three common peptides (VFEAGRDPYKLRPVAAE, FENLPEKADRDQYEL, and VLRPTEGYL) and four differential peptides (GILRPYLSWTE, ARSVDGKEDLIWKL, YLGSRYLT, and FKSETKNLL). The gastric digest of LfPF contained more diverse and abundant detectable peptides of longer lengths than those of bLf and LfPFTG. After further in vitro intestinal digestion, two active peptide-related fragments (FEAGRDPYK and FENLPEKADRDQYE) remained in the final digest of LfPFTG; one (EAGRDPYKLRPVA) remained in that of bLf alone, but none remained in that of LfPF. Conclusively, PF encapsulation enhanced the production of bLf active peptide fragments under the in vitro gastric digestion applied. TG treatment facilitated active peptide FENLPEKADRDQYE being kept in the final gastrointestinal digest.

Enzymatic one-pot preparation of carboxylmethyl chitosan-based hydrogel with inherent antioxidant and antibacterial properties for accelerating wound healing

Facile preparation of multifunctional hydrogel wound dressings with inherent versatile properties is highly desirable in practical healthcare. Here, a biocompatible hydrogel was designed and fabricated via mild enzymatic crosslinking and polymerization. We first designed an enzymatic system containing horseradish peroxidase (HRP), H₂O₂, and the macromolecular initiator-acetoacetyl polyvinyl alcohol (PVA-ACAC), which can generate active PVA-ACAC carbon radicals via HRP-mediated oxidation by H₂O₂. Trimethylammonium chloride (Q), methacryloyl (MA) and phenol (Ph)-grafted carboxymethyl chitosan (Ph-QCMCS-MA) was then synthesized. HRP catalyzes the oxidation of phenol groups to achieve the fast phenol crosslinking, and PVA-ACAC carbon radicals initiate the polymerization of MA groups simultaneously, finally obtaining the target PPQM gel. The quaternary ammonium and phenol groups endow the PPQM gel with excellent antibacterial and antioxidant properties, respectively. This multifunctional hydrogel, which has additional adhesive and hemostatic properties, could promote wound healing processes in an in vivo full-thickness skin defect experiment by reducing the generation of pro-inflammatory cytokines (IL-6) and upregulating anti-inflammatory factors (IL-10) and angiogenesis-related cytokines (VEGF and α-SMA). As a result, it could be used as competitive wound dressings.

Rational design cold-set interpenetrating network hydrogel based on wheat bran arabinoxylans and pea protein isolates for regulating the release of riboflavin in simulated digestion

Cold-set interpenetrating polymer network gels as riboflavin (RF) delivery vehicles based on wheat bran arabinoxylans (AX) and pea protein isolate (PPI) were developed via enzymatic-crosslinking. The impact of AX concentrations on the physicochemical property, in vitro digestion property and microstructure of IPN gels was explored. Increased concentrations of AX enhanced the viscoelasticity of IPN gels and resulted in a more compact microstructure. However, at a concentration of 5.0 % (w/v), the faster and stronger crosslinking of AX molecules caused separate network gel between PPI and AX. The IPN gel improved the encapsulation efficiency and release property of embedded RF as compared to PPI gel. SEM results showed that IPN gel maintained a complete network structure after gastric digestion. Particularly, the IPN gel with 1.0 % AX exhibited a homogeneous and complete network structure even after intestinal digestion, which explained the reason for the highest encapsulation efficiency and lowest release ratios of RF.

Gasotransmitter-Induced Therapeutic Angiogenesis: A Biomaterial Prospective

Gasotransmitters such as NO, H₂S, and CO have emerged as key players in the regulation of various pathophysiological functions, prompting the development of gas therapy for various pathogeneses. Deficient production of gasotransmitters has been linked to various diseases such as hypertension, endothelial dysfunction, myocardial infarction, ischemia, and impaired wound healing, as they are involved in the regulatory action of angiogenesis. A better understanding of the regulatory mechanisms has given new hope to address the vascular impairment caused by the breakthroughs in gasotransmitters as therapeutics. However, the unstable nature and poor target specificity of gas donors limit the full efficacy of drugs. In this regard, biomaterials that possess excellent biocompatibility and porosity are ideal drug carriers to deliver the gas transmitters in a tunable manner for therapeutic angiogenesis. This review article provides a comprehensive discussion of biomaterial-based gasotransmitter delivery approaches for therapeutic angiogenesis. The critical role of gasotransmitters in modulating angiogenesis during tissue repair as well as their challenges and future directions are demonstrated.

Chitosan–Hydroxycinnamic Acids Conjugates: Emerging Biomaterials with Rising Applications in Biomedicine

Over the past thirty years, research has shown the huge potential of chitosan in biomedical applications such as drug delivery, tissue engineering and regeneration, cancer therapy, and antimicrobial treatments, among others. One of the major advantages of this interesting polysaccharide is its modifiability, which facilitates its use in tailor-made applications. In this way, the molecular structure of chitosan has been conjugated with multiple molecules to modify its mechanical, biological, or chemical properties. Here, we review the conjugation of chitosan with some bioactive molecules: hydroxycinnamic acids (HCAs); since these derivatives have been probed to enhance some of the biological effects of chitosan and to fine-tune its characteristics for its application in the biomedical field. First, the main characteristics of chitosan and HCAs are presented; then, the currently employed conjugation strategies between chitosan and HCAs are described; and, finally, the studied biomedical applications of these derivatives are discussed to present their limitations and advantages, which could lead to proximal therapeutic uses.

A comprehensive review of food gels: formation mechanisms, functions, applications, and challenges

Gels refer to the soft and flexible macromolecular polymeric materials retaining a large amount of water or biofluids in their three-dimensional network structure. Gels have attracted increasing interest in the food discipline, especially proteins and polysaccharides, due to their good biocompatibility, biodegradability, nutritional properties, and edibility. With the advancement of living standards, people's demand for nutritious, safe, reliable, and functionally diverse food and even personalized food has increased. As a result, gels exhibiting unique advantages in food application will be of great significance. However, a comprehensive review of functional hydrogels as food gels is still lacking. Here, we comprehensively review the gel-forming mechanisms of food gels and systematically classify them. Moreover, the potential of hydrogels as functional foods in different types of food areas is summarized, with a special focus on their applications in food packaging, satiating gels, nutrient delivery systems, food coloring adsorption, and food safety monitoring. Additionally, the key scientific issues for future food gel research, with specific reference to future novel food designs, mechanisms between food components and matrices, food gel-human interactions, and food gel safety, are discussed. Finally, the future directions of hydrogels for food science and technology are summarized.