Effect of ethanol treatment on physical property of photopolymerized hyaluronic acid/silk fibroin hybrid hydrogel

Evaluation of citrus pectin extraction methods: Synergistic enhancement of pectin's antioxidant capacity and gel properties through combined use of organic acids, ultrasonication, and microwaves

The biological potency of pectin is intricately intertwined with its intricate molecular architecture. The fine structure of pectin is influenced by the extraction method, while the specific impact of these methods on the fine structure and the affected attributes thereof remains enigmatic. This study delves into the profound analysis of eight distinct extraction methods influence on the structure and biological activity of citrus peel pectin. The findings demonstrate that citric acid ultrasound-assisted microwave extraction yields pectin (PectinCA-US/MV) with higher viscosity and a dense, rigid chain. Pectin extracted with acetic acid ultrasound (PectinAA-US) and citric acid ultrasound (PectinCA-US) exhibits elevated galacturonic acid (GalA) levels and reduced D-galactose (Gal) content, enhancing antioxidant activity. Eight pectin-chitosan (CS) hydrogels, especially PectinCA-US/MV-CS, demonstrate commendable thermal stability, rheological properties, self-healing capability, and swelling behavior. This study characterizes citrus peel pectin properties from different extraction methods, laying a foundation for its application in food, pharmaceuticals, and industry.

Recent advances in photo-crosslinkable methacrylated silk (Sil-MA)-based scaffolds for regenerative medicine: A review

Silks fibroin can be chemically modified through amino acid side chains to obtain methacrylated silk (Sil-MA). Sil-MA could be processed into a variety of scaffold forms and combine synergistically with other biomaterials to form composites vehicle. The advent of Sil-MA material has enabled impressive progress in the development of various scaffolds based on Sil-MA type to imitate the structural and functional characteristics of natural tissues. This review highlights the reasonable design and bio-fabrication strategies of diverse Sil-MA-based tissue constructs for regenerative medicine. First, we elucidate modification methodology and characteristics of Sil-MA. Next, we describe characteristics of Sil-MA hydrogels, and focus on the design approaches and formation of different types of Sil-MA-based hydrogels. Thereafter, we present an overview of the recent advances in the application of Sil-MA based scaffolds for regenerative medicine, including detailed strategies for the engineering methods and materials used. Finally, we summarize the current research progress and future directions of Sil-MA in regenerative medicine. This review not only delineates the representative design strategies and their application in regenerative medicine, but also provides new direction in the fabrication of biomaterial constructs for the clinical translation in order to stimulate the future development of implants.

Ce(IV)-coordinated organogel-based assay for on-site monitoring of propyl gallate with turn-on fluorescence signal

Propyl gallate (PG) is a commonly used synthetic phenolic antioxidant in foodstuffs and industrial products. Due to the potential health risk of PG, rapid and on-site detection in food and environment samples are important to guarantee human health. Herein, we demonstrated rapid monitoring of PG by a fluorescence turn-on strategy based on a specific fluorogenic reaction between PG and polyethyleneimine (PEI). Specifically, Ce4+ with oxidase-mimicking activity oxidized PG to its oxides, which then reacted with PEI through the Michael addition to generate the fluorescent compound. The proposed fluorogenic reaction had good specificity for PG, which could distinguish PG from other phenolic antioxidants and interferences. Furthermore, portable and low-cost organogel test kits were prepared using poly(ethylene glycol) diacrylate for quantitative and on-site detection of PG via a smartphone-based sensing platform. The organogel-based assay detection limit was 1.0 μg mL-1 with recoveries ranging from 80.2% to 106.2% in edible oils and surface water. Suitability of the developed assay was also validated by high-performance liquid chromatography. Our study provides an effective fluorescent approach to rapid, specific, and convenient monitoring of PG, which is useful for diminishing the risk of PG exposure.

Hyaluronic Acid as Bioink and Hydrogel Scaffolds for Tissue Engineering Applications

Bioprinting is an additive manufacturing technique that focuses on developing living tissue constructs using bioinks. Bioink is crucial in determining the stability of printed patterns, which remains a major challenge in bioprinting. Thus, the choices of bioink composition, modifications, and cross-linking methods are being continuously researched to augment the clinical translation of bioprinted constructs. Hyaluronic acid (HA) is a naturally occurring polysaccharide with the repeating unit of N-acetyl-glucosamine and d-glucuronic acid disaccharides. It is present in the extracellular matrix (ECM) of tissues (skin, cartilage, nerve, muscle, etc.) with a wide range of molecular weights. Due to the nature of its chemical structure, HA could be easily subjected to chemical modifications and cross-linking that would enable better printability and stability. These interesting properties have made HA an ideal choice of bioinks for developing tissue constructs for regenerative medicine applications. In this Review, the physicochemical properties, reaction chemistry involved in various cross-linking strategies, and biomedical applications of HA have been elaborately discussed. Further, the features of HA bioinks, emerging strategies in HA bioink preparations, and their applications in 3D bioprinting have been highlighted. Finally, the current challenges and future perspectives in the clinical translation of HA-based bioinks are outlined.

Electro-stimulated drug release by methacrylated hyaluronic acid-based conductive hydrogel with enhanced mechanical properties

Recently, the design of stimuli-responsive hydrogels for controlled drug delivery systems has been extensively investigated to meet therapeutic needs and optimize the release pattern of the drug. Being a natural polyelectrolyte, hyaluronic acid (HA) is excellent potential to generate new opportunities for electro-responsive drug carrier applications. In the current study, HA-based electroconductive hydrogel was developed as a novel smart drug carrier for anti-inflammatory drug release by the combination of in-situ and post polymerization mechanisms. HA was modified through methacrylation reaction to introduce photocrosslinkable groups into its structure and then reduced graphene oxide (rGO) was encapsulated into methacrylated HA (HA/MA) hydrogel by using the photopolymerization technique. In the post polymerization process, polyaniline (PANI) was incorporated/loaded into HA/MA-rGO polymeric network produced in previous step. The produced HA/MA-rGO-PANI hydrogel exhibited sufficient electrical conductivity providing the desirable electro-responsive ability for Ibuprofen (IBU) release. Furthermore, it has superior mechanical performance compared to pure (HA/MA) and rGO containing (HA/MA-rGO) hydrogels. IBU release from the hydrogel was successfully triggered by electrical stimulation and the cumulative drug release also enhanced by increasing of the applied voltage. These results highlighted that the novel HA/MA-rGO-PANI hydrogel could be a promising candidate for electrical-stimulated anti-inflammatory release systems in neural implant applications.

From crosslinking strategies to biomedical applications of hyaluronic acid-based hydrogels: A review

Hyaluronic acid (HA) is not only a natural anionic polysaccharide with excellent biocompatibility, biodegradability, and moisturizing effect, but also an essential factor that can affect angiogenesis, inflammation, cell behavior, which has a wide range of applications in the biomedical field. Among them, HA-based hydrogels formed by various physical or chemical crosslinking strategies are particularly striking. They not only retain the physiological function of HA, but also have the skeleton function of hydrogel, which further expands the application of HA. However, HA-based natural hydrogels generally have problems such as insufficient mechanical strength and susceptibility to degradation by hyaluronidase, which limits their application to a certain extent. To solve such problems, researchers have prepared a variety of HA-based multifunctional hydrogels with remarkable properties in recent years by adopting various structural modification methods or novel crosslinking strategies, as well as introducing functionally reactive molecules or moieties, which have extended the application scope. This manuscript systematically introduced common crosslinking strategies of HA-based hydrogels and highlighted the development of novel HA-based hydrogels in anticancer drug delivery, cartilage repair, three-dimensional cell culture, skin dressing and other fields. We hope to provide some references for the subsequent development of HA-based hydrogels in the biomedical field.

Accelerated Simple Preparation of Curcumin-Loaded Silk Fibroin/Hyaluronic Acid Hydrogels for Biomedical Applications

The development of new biomaterials from natural fibres in the field of biomedicine have attracted great interest in recent years. One of the most studied fibres has been silk fibroin produced by the Bombyx mori worm, due to its excellent mechanical properties and its biodegradability and bioavailability. Among the different biomaterials that can be prepared from silk fibroin, hydrogels have attracted considerable attention due to their potential use in different fields, such as scaffolding, cell therapy and biomedical application. Hydrogels are essentially a three-dimensional network of flexible polymer chains that absorb considerable amounts of water and can be loaded with drugs and/or cells inside to be used in a wide variety of applications. Here we present a simple sonication process for the preparation of curcumin-hyaluronic acid-silk fibroin hydrogels. Different grades of hydrogels were prepared by controlling the relative amounts of their components. The hydrogels were physically and morphologically characterised by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM) and their biological activity was tested in terms of cell viability in a fibroblast cell line.

Dityrosine-inspired photocrosslinking technique for 3D printing of silk fibroin-based composite hydrogel scaffolds

Photoinduced self-crosslinking technology is a great facilitator of 3D bioprinting of silk fibroin (SF) by allowing rapid solidification of a deliberately formulated SF-based photocrosslinkable bioink. An SF-based, photocrosslinked hydrogel was fabricated with tyramine-modified sodium carboxymethyl cellulose (CMC-Na) as a co-crosslinkable constituent and Ru(bpy)₃Cl₂ (Ru(II)) and potassium persulfate (KPS) as blue light photoinitiators. Photorheological studies demonstrated that the photocrosslinking and viscoelasticity of the composite could be tuned by varying the relative content of the two constituents. Xanthan gum (XG) was employed in formulating the SF-based photocrosslinkable bioink, and the improved rheological properties and printability were evidenced by the resulting tunable shear-thinning behavior and shear thixotropy. 3D SF-based hydrogel scaffolds with uniform pores with a size of approximately 550 μm × 1000 μm were constructed via extrusion-based printing and a simple 30 s post-photocrosslinking combined process. Furthermore, the CMC-Na incorporated 3D hydrogel scaffolds exhibited sufficient structural strength, adequate filament fineness, and tunable transparency, which shows a promising prospect in the application of tissue engineering and regenerative medicine.

Highly Absorbent Silk Fibroin Protein Xerogel

Highly absorbent polymers have a wide range of applications in biomaterials, agriculture, physiological products of daily uses, and others. Silk fibroin, as a natural biomaterial with excellent biocompatibility and tunable mechanical properties, shows good prospects in the field of biomedicine applications. However, the dried fibroin hydrogel has very low absorbency. In this work, silk fibroin protein is used as the carrier, riboflavin as the photosensitizer, and accordingly, the hydrogel is prepared by free radical cross-linking under ultraviolet light. The fibroin in the hydrogel contains mainly the random coil structure. The covalent bond cross-linking hinders the crystallization of the silk fibroin, thereby an amorphous silk fibroin hydrogel is obtained. After drying, this xerogel can absorb water 90 times more than its own mass and assimilates a good amount of water within a minute. In vitro and in vivo rabbit ear hemostasis experiments show that this fabricated xerogel has good hemostatic properties. Therefore, this xerogel exhibits good promise for rapid hemostasis of wounds and absorbing other body exudates.

How to Improve Physico-Chemical Properties of Silk Fibroin Materials for Biomedical Applications?-Blending and Cross-Linking of Silk Fibroin-A Review

This review supplies a report on fresh advances in the field of silk fibroin (SF) biopolymer and its blends with biopolymers as new biomaterials. The review also includes a subsection about silk fibroin mixtures with synthetic polymers. Silk fibroin is commonly used to receive biomaterials. However, the materials based on pure polymer present low mechanical parameters, and high enzymatic degradation rate. These properties can be problematic for tissue engineering applications. An increased interest in two- and three-component mixtures and chemically cross-linked materials has been observed due to their improved physico-chemical properties. These materials can be attractive and desirable for both academic, and, industrial attention because they expose improvements in properties required in the biomedical field. The structure, forms, methods of preparation, and some physico-chemical properties of silk fibroin are discussed in this review. Detailed examples are also given from scientific reports and practical experiments. The most common biopolymers: collagen (Coll), chitosan (CTS), alginate (AL), and hyaluronic acid (HA) are discussed as components of silk fibroin-based mixtures. Examples of binary and ternary mixtures, composites with the addition of magnetic particles, hydroxyapatite or titanium dioxide are also included and given. Additionally, the advantages and disadvantages of chemical, physical, and enzymatic cross-linking were demonstrated.

Crosslinking strategies for silk fibroin hydrogels: promising biomedical materials

Due to their strong biomimetic potential, silk fibroin (SF) hydrogels are impressive candidates for tissue engineering, due to their tunable mechanical properties, biocompatibility, low immunotoxicity, controllable biodegradability, and a remarkable capacity for biomaterial modification and the realization of a specific molecular structure. The fundamental chemical and physical structure of SF allows its structure to be altered using various crosslinking strategies. The established crosslinking methods enable the formation of three-dimensional (3D) networks under physiological conditions. There are different chemical and physical crosslinking mechanisms available for the generation of SF hydrogels (SFHs). These methods, either chemical or physical, change the structure of SF and improve its mechanical stability, although each method has its advantages and disadvantages. While chemical crosslinking agents guarantee the mechanical strength of SFH through the generation of covalent bonds, they could cause some toxicity, and their usage is not compatible with a cell-friendly technology. On the other hand, physical crosslinking approaches have been implemented in the absence of chemical solvents by the induction of β-sheet conformation in the SF structure. Unfortunately, it is not easy to control the shape and properties of SFHs when using this method. The current review discusses the different crosslinking mechanisms of SFH in detail, in order to support the development of engineered SFHs for biomedical applications.