Electrospinning of gelatin for tissue engineering--molecular conformation as one of the overlooked problems

Characterization and molecular docking of sustainable wine lees and gelatin-based emulsions: innovative fat substitution

BACKGROUND

The present study aimed to determine how various amounts (0.00, 0.58, 1.52 and 4.50 g 100 g-1) of wine lees (WL), which contains numerous essential components, impact the emulsifying properties of fish gelatin (FG) at a low concentration (0.5 g 100 g-1) in the high-fat phase (65 g 100 g-1). This study conducted rheology, physicochemical technical and characterization analyses on the emulsions to provide sustainable and innovative approaches for spreadable oils.

RESULTS

The addition of WL to FG emulsions improved oxidative stability, emulsion stability and bioactive compounds. The zeta potential (-101 ± 5.62 mV) of 0.58 g 100 g-1 WL-containing emulsion (PE1) was found to be high, whereas particle size (347.6 ± 5.25 nm) and polydispersity index (0.50) were statistically low. It was also found that the addition of WL improved the intermolecular interactions, crystallinity and microstructural properties of the emulsions. All these results were supported by simulating the molecular configuration between FG and WL. The compounds gallic acid, caffeic acid, myricetin, quercetin and resveratrol showed a strong affinity to FG, with free binding energies of -5.50, -5.88, -6.53, -6.68 and -6.66 kcal mol-1, respectively.

CONCLUSION

As a result, WL-supported FG has the potential to be used as an alternative to egg proteins to develop sustainable low-cost spreadable emulsions. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Electrospun nanofibrous wound dressings with enhanced efficiency through carbon quantum dots and citrate incorporation

Nanofibers show promise for wound healing by facilitating active agent delivery, moisture retention, and tissue regeneration. However, selecting suitable dressings for diverse wound types and managing varying exudate levels remains challenging. This study synthesized carbon quantum dots (CQDs) from citrate salt and thiourea using a hydrothermal method. The CQDs displayed antibacterial activity against Staphylococcus aureus and Escherichia coli. A nanoscaffold comprising gelatin, chitosan, and polycaprolactone (GCP) was synthesized and enhanced with silver nanoparticle-coated CQDs (Ag-CQDs) to form GCP-Q, while citrate addition yielded GCP-QC. Multiple analytical techniques, including electron microscopy, FT-IR spectroscopy, dynamic light scattering, UV-Vis, photoluminescence, X-ray diffraction, porosity, degradability, contact angle, and histopathology assessments characterized the CQDs and nanofibers. Integration of CQDs and citrate into the GCP nanofibers increased porosity, hydrophilicity, and degradability-properties favorable for wound healing. Hematoxylin and eosin staining showed accelerated wound closure with GCP-Q and GCP-QC compared to GCP alone. Overall, GCP-Q and GCP-QC nanofibers exhibit significant potential for skin tissue engineering applications.

Advancing gelatin/cinnamaldehyde O/W emulsions electrospinability: Role of soybean lecithin in core-shell nanofiber fabrication

The main objective of this study is to investigate the impact and mechanism of soy lecithin incorporation into the gelatin-cinnamaldehyde emulsion, focusing on how it influences emulsion stability during the electrospinning process. In this work, a cinnamaldehyde/gelatin/soy lecithin (CGS) fiber membrane with excellent antibacterial properties was successfully created. The addition of soy lecithin improves the stability of the emulsion and improves the loading performance and fiber morphology of the CGS fiber membrane. Fourier Transform infrared spectroscopy (FTIR) and urea addition confirmed that soy lecithin may strengthen the interface structure of gelatin in the oil and water phases through hydrogen bonds, thus enhancing the stability of the emulsion in electrospinning. The application tests also revealed that the CGS fiber membrane effectively preserved the sensory quality of beef. This study indicates that the vector construction method can extend the utilization of cinnamaldehyde in food industry.

Materials based on biodegradable polymers chitosan/gelatin: a review of potential applications

Increased mass manufacturing and the pervasive use of plastics in many facets of daily life have had detrimental effects on the environment. As a result, these worries heighten the possibility of climate change due to the carbon dioxide emissions from burning conventional, non-biodegradable polymers. Accordingly, biodegradable gelatin and chitosan polymers are being created as a sustainable substitute for non-biodegradable polymeric materials in various applications. Chitosan is the only naturally occurring cationic alkaline polysaccharide, a well-known edible polymer derived from chitin. The biological activities of chitosan, such as its antioxidant, anticancer, and antimicrobial qualities, have recently piqued the interest of researchers. Similarly, gelatin is a naturally occurring polymer derived from the hydrolytic breakdown of collagen protein and offers various medicinal advantages owing to its unique amino acid composition. In this review, we present an overview of recent studies focusing on applying chitosan and gelatin polymers in various fields. These include using gelatin and chitosan as food packaging, antioxidants and antimicrobial properties, properties encapsulating biologically active substances, tissue engineering, microencapsulation technology, water treatment, and drug delivery. This review emphasizes the significance of investigating sustainable options for non-biodegradable plastics. It showcases the diverse uses of gelatin and chitosan polymers in tackling environmental issues and driving progress across different industries.

Design of Collagen and Gelatin-based Electrospun Fibers for Biomedical Purposes: An Overview

Collagen and gelatin are essential natural biopolymers commonly utilized in biomaterials and tissue engineering because of their excellent physicochemical and biocompatibility properties. They can be used either in combination with other biomacromolecules or particles or even exclusively for the enhancement of bone regeneration or for the development of biomimetic scaffolds. Collagen or gelatin derivatives can be transformed into nanofibrous materials with porous micro- or nanostructures and superior mechanical properties and biocompatibility using electrospinning technology. Specific attention was recently paid to electrospun mats of such biopolymers, due to their high ratio of surface area to volume, as well as their biocompatibility, biodegradability, and low immunogenicity. The fiber mats with submicro- and nanometer scale can replicate the extracellular matrix structure of human tissues and organs, making them highly suitable for use in tissue engineering due to their exceptional bioaffinity. The drawbacks may include rapid degradation and complete dissolution in aqueous media. The use of gelatin/collagen electrospun nanofibers in this form is thus greatly restricted for biomedicine. Therefore, the cross-linking of these fibers is necessary for controlling their aqueous solubility. This led to enhanced biological characteristics of the fibers, rendering them excellent options for various biomedical uses. The objective of this review is to highlight the key research related to the electrospinning of collagen and gelatin, as well as their applications in the biomedical field. The review features a detailed examination of the electrospinning fiber mats, showcasing their varying structures and performances resulting from diverse solvents, electrospinning processes, and cross-linking methods. Judiciously selected examples from literature will be presented to demonstrate major advantages of such biofibers. The current developments and difficulties in this area of research are also being addressed.

Enhancing periodontal defences with nanofiber treatment: recent advances and future prospects

The term periodontal disease is used to define diseases characterised by inflammation and regeneration of the gums, cementum, supporting bone, and periodontal ligament. The conventional treatment involves the combination of scaling, root planning, and surgical approaches which are invasive and can pose certain challenges. Intrapocket administration of nanofibers can be used for overcoming challenges which can help in speeding up the wound repair process and can also be used to promote osteogenesis. To help make drug delivery more effective, nanofibers are an interesting solution. Nanofibers are nanosized 3D structures that can fill the pockets and have excellent mucoadhesion which prolongs their retention time on the target site. Moreover, their structure mimics the natural extracellular matrix which enables nanomaterials to sense local biological conditions and start cellular-level reprogramming to produce the necessary therapeutic efficacy. In this review, the significance of intrapocket administration of nanofibers using recent research for the management of periodontitis has been discussed in detail. Furthermore, we have discussed polymers used for the preparation of nanofibers, nanofiber production methods, and the patents associated with these developments. This comprehensive compilation of data serves as a valuable resource, consolidating recent developments in nanofiber applications for periodontitis management into one accessible platform.

Recent Advances in Electrospinning Techniques for Precise Medicine

In the realm of precise medicine, the advancement of manufacturing technologies is vital for enhancing the capabilities of medical devices such as nano/microrobots, wearable/implantable biosensors, and organ-on-chip systems, which serve to accurately acquire and analyze patients' physiopathological information and to perform patient-specific therapy. Electrospinning holds great promise in engineering materials and components for advanced medical devices, due to the demonstrated ability to advance the development of nanomaterial science. Nevertheless, challenges such as limited composition variety, uncontrollable fiber orientation, difficulties in incorporating fragile molecules and cells, and low production effectiveness hindered its further application. To overcome these challenges, advanced electrospinning techniques have been explored to manufacture functional composites, orchestrated structures, living constructs, and scale-up fabrication. This review delves into the recent advances of electrospinning techniques and underscores their potential in revolutionizing the field of precise medicine, upon introducing the fundamental information of conventional electrospinning techniques, as well as discussing the current challenges and future perspectives.

Labile assembly of a tardigrade protein induces biostasis

Tardigrades are microscopic animals that survive desiccation by inducing biostasis. To survive drying tardigrades rely on intrinsically disordered CAHS proteins, which also function to prevent perturbations induced by drying in vitro and in heterologous systems. CAHS proteins have been shown to form gels both in vitro and in vivo, which has been speculated to be linked to their protective capacity. However, the sequence features and mechanisms underlying gel formation and the necessity of gelation for protection have not been demonstrated. Here we report a mechanism of fibrillization and gelation for CAHS D similar to that of intermediate filament assembly. We show that in vitro, gelation restricts molecular motion, immobilizing and protecting labile material from the harmful effects of drying. In vivo, we observe that CAHS D forms fibrillar networks during osmotic stress. Fibrillar networking of CAHS D improves survival of osmotically shocked cells. We observe two emergent properties associated with fibrillization; (i) prevention of cell volume change and (ii) reduction of metabolic activity during osmotic shock. We find that there is no significant correlation between maintenance of cell volume and survival, while there is a significant correlation between reduced metabolism and survival. Importantly, CAHS D's fibrillar network formation is reversible and metabolic rates return to control levels after CAHS fibers are resolved. This work provides insights into how tardigrades induce reversible biostasis through the self-assembly of labile CAHS gels.

A comprehensive review on nanocomposite biomaterials based on gelatin for bone tissue engineering

The creation of a suitable scaffold is a crucial step in the process of bone tissue engineering (BTE). The scaffold, acting as an artificial extracellular matrix, plays a significant role in determining the fate of cells by affecting their proliferation and differentiation in BTE. Therefore, careful consideration should be given to the fabrication approach and materials used for scaffold preparation. Natural polypeptides such as gelatin and collagen have been widely used for this purpose. The unique properties of nanoparticles, which vary depending on their size, charge, and physicochemical properties, have demonstrated potential in solving various challenges encountered in BTE. Therefore, nanocomposite biomaterials consisting of polymers and nanoparticles have been extensively used for BTE. Gelatin has also been utilized in combination with other nanomaterials to apply for this purpose. Composites of gelatin with various types of nanoparticles are particularly promising for creating scaffolds with superior biological and physicochemical properties. This review explores the use of nanocomposite biomaterials based on gelatin and various types of nanoparticles together for applications in bone tissue engineering.

Recent Advances in Electrospun Nanofiber-Based Strategies for Diabetic Wound Healing Application

Diabetic ulcers are the second largest complication caused by diabetes mellitus. A great number of factors, including hyperchromic inflammation, susceptible microbial infection, inferior vascularization, the large accumulation of free radicals, and other poor healing-promoting microenvironments hold back the healing process of chronic diabetic ulcer in clinics. With the increasing clinical cases of diabetic ulcers worldwide, the design and development of advanced wound dressings are urgently required to accelerate the treatment of skin wounds caused by diabetic complications. Electrospinning technology has been recognized as a simple, versatile, and cost-reasonable strategy to fabricate dressing materials composed of nanofibers, which possess excellent extracellular matrix (ECM)-mimicking morphology, structure, and biological functions. The electrospinning-based nanofibrous dressings have been widely demonstrated to promote the adhesion, migration, and proliferation of dermal fibroblasts, and further accelerate the wound healing process compared with some other dressing types like traditional cotton gauze and medical sponges, etc. Moreover, the electrospun nanofibers are commonly harvested in the structure of nonwoven-like mats, which possess small pore sizes but high porosity, resulting in great microbial barrier performance as well as excellent moisture and air permeable properties. They also serve as good carriers to load various bioactive agents and/or even living cells, which further impart the electrospinning-based dressings with predetermined biological functions and even multiple functions to significantly improve the healing outcomes of different chronic skin wounds while dramatically shortening the treatment procedure. All these outstanding characteristics have made electrospun nanofibrous dressings one of the most promising dressing candidates for the treatment of chronic diabetic ulcers. This review starts with a brief introduction to diabetic ulcer and the electrospinning process, and then provides a detailed introduction to recent advances in electrospinning-based strategies for the treatment of diabetic wounds. Importantly, the synergetic application of combining electrospinning with bioactive ingredients and/or cell therapy was highlighted. The review also discussed the advantages of hydrogel dressings by using electrospun nanofibers. At the end of the review, the challenge and prospects of electrospinning-based strategies for the treatment of diabetic wounds are discussed in depth.

Application of Noggin-Coated Electrospun Scaffold in Corneal Wound Healing

Purpose

The objective of this study is to develop and characterize electrospun corneal bandage infused with Noggin protein and evaluate its therapeutic potential in the treatment of superficial nonhealing corneal ulceration.

Methods

Electrospun nanofibrous scaffolds were created with different blend ratios of polycaprolactone and gelatin and coated with different concentrations of Noggin protein. Morphologic, mechanical, degradation, and surface chemistry of the developed scaffold was assessed. Biocompatibility of the developed scaffold with corneal epithelial cells was evaluated by looking at cell viability, proliferation, and immunostaining. In vitro wound healing in the presence of Noggin-coated scaffold was evaluated by measuring wound closure rate after scratch.

Results

Uniform nanofibrous scaffolds coated with Noggin were constructed through optimization of electrospinning parameters and demonstrated mechanical properties better than or similar to commercially available contact lenses used in corneal wound healing. In the presence of Noggin-coated scaffold, corneal epithelial cells showed higher proliferation and wound-healing rate.

Conclusions

This Noggin-coated electrospun scaffold represents a step toward, expanding treatment options for patients with indolent corneal ulcers.

Translational Relevance

In this study, the feasibility of Noggin-coated electrospun scaffold as a therapeutic for indolent corneal ulcer was evaluated. This study also provides a better perspective for understanding electrospun scaffolds as a tunable platform to infuse topical therapeutics and use as a corneal bandage.

A review on polysaccharides mediated electrospun nanofibers for diabetic wound healing: Their current status with regulatory perspective

The current treatment strategies for diabetic wound care provide only moderate degree of effectiveness; hence new and improved therapeutic techniques are in great demand. Diabetic wound healing is a complex physiological process that involves synchronisation of various biological events such as haemostasis, inflammation, and remodelling. Nanomaterials like polymeric nanofibers (NFs) offer a promising approach for the treatment of diabetic wounds and have emerged as viable options for wound management. Electrospinning is a powerful and cost-effective method to fabricate versatile NFs with a wide array of raw materials for different biological applications. The electrospun NFs have unique advantages in the development of wound dressings due to their high specific surface area and porosity. The electrospun NFs possess a unique porous structure and biological function similar to the natural extracellular matrix (ECM), and are known to accelerate wound healing. Compared to traditional dressings, the electrospun NFs are more effective in healing wounds owing to their distinct characteristics, good surface functionalisation, better biocompatibility and biodegradability. This review provides a comprehensive overview of the electrospinning procedure and its operating principle, with special emphasis on the role of electrospun NFs in the treatment of diabetic wounds. This review discusses the present techniques applied in the fabrication of NF dressings, and highlights the future prospects of electrospun NFs in medicinal applications.

Poly (l-lactic acid)-based modified nanofibrous membrane with dual drug release capability for GBR application

Electrospun multilayer nanofibers guided bone regeneration (GBR) with a new design were developed in this study. The synthesized multilayer GBR was composed of two distinct layers. Poly l-lactic acid (PLA) incorporated with simvastatin (SIM) was designed as PLA/SIM layer to contact with a bone defect. In addition, the hydrophilic gelatin (GT) containing thymol (THY) was fabricated as GT/THY layer to contact connective tissue, potentially for bacterial gathering. Due to the different chemical nature and weak cohesion of the hydrophilic and hydrophobic layers, hybrid fibers made of PLA/SIM and GT/THY were electrospun as cohesion promoters between these layers. The microstructure and characteristics of the synthesized multilayer substrate, named GT/PLA, were evaluated, and different fibrous monolayers were fabricated to determine the optimal concentrations of drugs. Scanning electron microscopy (SEM) images showed continuous, smooth, randomly aligned, and bead-free fibers. In addition, there were no drug particles on the fiber surfaces which displayed the good placement of those inside the fibers. The mats exhibited satisfactory tensile strength (4.60 ± 0.14 MPa) and favorable physicochemical properties, including proper porosity percentage (<50 %) and appropriate pore size. Suitable swelling behavior (293 ± 0.05 %) and adequate degradation rates were also approved by characterizing swelling and degradability in vitro. The GT/PLA membrane exhibited a prolonged and sustained SIM release and controlled THY release with high antibacterial efficiency. Cell viability, cell attachment assay, and nuclear staining using 4',6-diamidino-2-phenylindole (DAPI) showed that the designed GT/PLA substrate had good biocompatibility and cell attachment. Cell infiltration testing also showed that the cells were finely prevented by the outer layer (GT/THY). Overall, the obtained results in this study indicated the great potential of the prepared GT/PLA for use as a GBR which can develop osteogenic and antibacterial biomimetic periosteum optimizing the clinical application of GBR strategies.

Electrospun Nanofibers for Periodontal Treatment: A Recent Progress

Periodontitis is a major threat to oral health, prompting scientists to continuously study new treatment techniques. The nanofibrous membrane prepared via electrospinning has a large specific surface area and high porosity. On the one hand, electrospun nanofibers can improve the absorption capacity of proteins and promote the expression of specific genes. On the other hand, they can improve cell adhesion properties and prevent fibroblasts from passing through the barrier membrane. Therefore, electrospinning has unique advantages in periodontal treatment. At present, many oral nanofibrous membranes with antibacterial, anti-inflammatory, and tissue regeneration properties have been prepared for periodontal treatment. First, this paper introduces the electrospinning process. Then, the commonly used polymers of electrospun nanofibrous membranes for treating periodontitis are summarized. Finally, different types of nanofibrous membranes prepared via electrospinning for periodontal treatment are presented, and the future evolution of electrospinning to treat periodontitis is described.

In Situ Transformation of Electrospun Nanofibers into Nanofiber-Reinforced Hydrogels

Nanofiber-reinforced hydrogels have recently gained attention in biomedical engineering. Such three-dimensional scaffolds show the mechanical strength and toughness of fibers while benefiting from the cooling and absorbing properties of hydrogels as well as a large pore size, potentially aiding cell migration. While many of such systems are prepared by complicated processes where fibers are produced separately to later be embedded in a hydrogel, we here provide proof of concept for a one-step solution. In more detail, we produced core-shell nanofibers from the natural proteins zein and gelatin by coaxial electrospinning. Upon hydration, the nanofibers were capable of directly transforming into a nanofiber-reinforced hydrogel, where the nanofibrous structure was retained by the zein core, while the gelatin-based shell turned into a hydrogel matrix. Our nanofiber-hydrogel composite showed swelling to ~800% of its original volume and water uptake of up to ~2500% in weight. The physical integrity of the nanofiber-reinforced hydrogel was found to be significantly improved in comparison to a hydrogel system without nanofibers. Additionally, tetracycline hydrochloride was incorporated into the fibers as an antimicrobial agent, and antimicrobial activity against Staphylococcus aureus and Escherichia coli was confirmed.

Electrospun Carbon Nanotube-Based Scaffolds Exhibit High Conductivity and Cytocompatibility for Tissue Engineering Applications

Carbon nanotubes (CNTs) are known for their excellent conductive properties. Here, we present two novel methods, "sandwich" (sCNT) and dual deposition (DD CNT), for incorporating CNTs into electrospun polycaprolactone (PCL) and gelatin scaffolds to increase their conductance. Based on CNT percentage, the DD CNT scaffolds contain significantly higher quantities of CNTs than the sCNT scaffolds. The inclusion of CNTs increased the electrical conductance of scaffolds from 0.0 ± 0.00 kS (non-CNT) to 0.54 ± 0.10 kS (sCNT) and 5.22 ± 0.49 kS (DD CNT) when measured parallel to CNT arrays and to 0.25 ± 0.003 kS (sCNT) and 2.85 ± 1.12 (DD CNT) when measured orthogonally to CNT arrays. The inclusion of CNTs increased fiber diameter and pore size, promoting cellular migration into the scaffolds. CNT inclusion also decreased the degradation rate and increased hydrophobicity of scaffolds. Additionally, CNT inclusion increased Young's modulus and failure load of scaffolds, increasing their mechanical robustness. Murine fibroblasts were maintained on the scaffolds for 30 days, demonstrating high cytocompatibility. The increased conductivity and high cytocompatibility of the CNT-incorporated scaffolds make them appropriate candidates for future use in cardiac and neural tissue engineering.

Physical and Mechanical Characteristics of Gelatin-Based Films as a Potential Food Packaging Material: A Review

This review discusses the potential application of gelatin-based film as biodegradable food packaging material from various types of gelatin sources. The exploitation of gelatin as one of the biopolymer packaging in the food industry has rising interest among researchers as the world becomes more concerned about environmental problems caused by petroleum-based packaging and increasing consumer demands on food safety. Single gelatin-based film properties have been characterized in comparison with active and intelligent gelatin-based composite films. The physical properties of gelatin-based film such as thickness, color, and biodegradability were much influenced by total solid contents in each film. While, for mechanical and light barrier properties, poultry-based gelatin films have shown better properties compared to mammalian and marine gelatin films. This paper detailed the information on gelatin-based film characterization in comparison with active and intelligent gelatin-based composite films. The physical properties of gelatin-based film such as color, UV-Vis absorption spectra, water vapor permeability, thermal, and moisture properties are discussed along with their mechanical properties, including tensile strength and elongation at break.

State-of-the-Art Review of Electrospun Gelatin-Based Nanofiber Dressings for Wound Healing Applications

Electrospun nanofiber materials have been considered as advanced dressing candidates in the perspective of wound healing and skin regeneration, originated from their high porosity and permeability to air and moisture, effective barrier performance of external pathogens, and fantastic extracellular matrix (ECM) fibril mimicking property. Gelatin is one of the most important natural biomaterials for the design and construction of electrospun nanofiber-based dressings, due to its excellent biocompatibility and biodegradability, and great exudate-absorbing capacity. Various crosslinking approaches including physical, chemical, and biological methods have been introduced to improve the mechanical stability of electrospun gelatin-based nanofiber mats. Some innovative electrospinning strategies, including blend electrospinning, emulsion electrospinning, and coaxial electrospinning, have been explored to improve the mechanical, physicochemical, and biological properties of gelatin-based nanofiber mats. Moreover, numerous bioactive components and therapeutic agents have been utilized to impart the electrospun gelatin-based nanofiber dressing materials with multiple functions, such as antimicrobial, anti-inflammation, antioxidation, hemostatic, and vascularization, as well as other healing-promoting capacities. Noticeably, electrospun gelatin-based nanofiber mats integrated with specific functions have been fabricated to treat some hard-healing wound types containing burn and diabetic wounds. This work provides a detailed review of electrospun gelatin-based nanofiber dressing materials without or with therapeutic agents for wound healing and skin regeneration applications.

Recent Advances in Microfluidically Spun Microfibers for Tissue Engineering and Drug Delivery Applications

In recent years, the unique and tunable properties of microfluidically spun microfibers have led to tremendous advancements for the field of biomedical engineering, which have been applied to areas such as tissue engineering, wound dressing, and drug delivery, as well as cell encapsulation and cell seeding. In this article, we analyze the most recent advances in microfluidics and microfluidically spun microfibers, with an emphasis on biomedical applications. We explore in detail these new and innovative experiments, how microfibers are made, the experimental purpose of making microfibers, and the future work that can be done as a result of these new types of microfibers. We also focus on the applications of various materials used to fabricate microfibers, as well as their many promises and limitations.

Soft Materials by Design: Unconventional Polymer Networks Give Extreme Properties

Hydrogels are polymer networks infiltrated with water. Many biological hydrogels in animal bodies such as muscles, heart valves, cartilages, and tendons possess extreme mechanical properties including being extremely tough, strong, resilient, adhesive, and fatigue-resistant. These mechanical properties are also critical for hydrogels' diverse applications ranging from drug delivery, tissue engineering, medical implants, wound dressings, and contact lenses to sensors, actuators, electronic devices, optical devices, batteries, water harvesters, and soft robots. Whereas numerous hydrogels have been developed over the last few decades, a set of general principles that can rationally guide the design of hydrogels using different materials and fabrication methods for various applications remain a central need in the field of soft materials. This review is aimed at synergistically reporting: (i) general design principles for hydrogels to achieve extreme mechanical and physical properties, (ii) implementation strategies for the design principles using unconventional polymer networks, and (iii) future directions for the orthogonal design of hydrogels to achieve multiple combined mechanical, physical, chemical, and biological properties. Because these design principles and implementation strategies are based on generic polymer networks, they are also applicable to other soft materials including elastomers and organogels. Overall, the review will not only provide comprehensive and systematic guidelines on the rational design of soft materials, but also provoke interdisciplinary discussions on a fundamental question: why does nature select soft materials with unconventional polymer networks to constitute the major parts of animal bodies?

Applications of Biocompatible Scaffold Materials in Stem Cell-Based Cartilage Tissue Engineering

Cartilage, especially articular cartilage, is a unique connective tissue consisting of chondrocytes and cartilage matrix that covers the surface of joints. It plays a critical role in maintaining joint durability and mobility by providing nearly frictionless articulation for mechanical load transmission between joints. Damage to the articular cartilage frequently results from sport-related injuries, systemic diseases, degeneration, trauma, or tumors. Failure to treat impaired cartilage may lead to osteoarthritis, affecting more than 25% of the adult population globally. Articular cartilage has a very low intrinsic self-repair capacity due to the limited proliferative ability of adult chondrocytes, lack of vascularization and innervation, slow matrix turnover, and low supply of progenitor cells. Furthermore, articular chondrocytes are encapsulated in low-nutrient, low-oxygen environment. While cartilage restoration techniques such as osteochondral transplantation, autologous chondrocyte implantation (ACI), and microfracture have been used to repair certain cartilage defects, the clinical outcomes are often mixed and undesirable. Cartilage tissue engineering (CTE) may hold promise to facilitate cartilage repair. Ideally, the prerequisites for successful CTE should include the use of effective chondrogenic factors, an ample supply of chondrogenic progenitors, and the employment of cell-friendly, biocompatible scaffold materials. Significant progress has been made on the above three fronts in past decade, which has been further facilitated by the advent of 3D bio-printing. In this review, we briefly discuss potential sources of chondrogenic progenitors. We then primarily focus on currently available chondrocyte-friendly scaffold materials, along with 3D bioprinting techniques, for their potential roles in effective CTE. It is hoped that this review will serve as a primer to bring cartilage biologists, synthetic chemists, biomechanical engineers, and 3D-bioprinting technologists together to expedite CTE process for eventual clinical applications.

Precise control of synthetic hydrogel network structure via linear, independent synthesis-swelling relationships

Hydrogel physical properties are tuned by altering synthesis conditions such as initial polymer concentration and polymer-cross-linker stoichiometric ratios. Traditionally, differences in hydrogel synthesis schemes, such as end-linked poly(ethylene glycol) diacrylate hydrogels and cross-linked poly(vinyl alcohol) hydrogels, limit structural comparison between hydrogels. In this study, we use generalized synthesis variables for hydrogels that emphasize how changes in formulation affect the resulting network structure. We identify two independent linear correlations between these synthesis variables and swelling behavior. Analysis through recently updated swollen polymer network models suggests that synthesis-swelling correlations can be used to make a priori predictions of the stiffness and solute diffusivity characteristics of synthetic hydrogels. The same experiments and analyses performed on methacrylamide-modified gelatin hydrogels demonstrate that complex biopolymer structures disrupt the linear synthesis-swelling correlations. These studies provide insight into the control of hydrogel physical properties through structural design and can be used to implement and optimize biomedically relevant hydrogels.

Electrospun Scaffolds in Periodontal Wound Healing

Periodontitis is a set of inflammatory conditions affecting the tissues surrounding the teeth predominantly sustained by bacterial infections. The aim of the work was the design and the development of scaffolds based on biopolymers to be inserted in the periodontal pocket to restore tissue integrity and to treat bacterial infections. Nanofibrous scaffolds were prepared by means of electrospinning. Gelatin was considered as base component and was associated to low and high molecular weight chitosans and alginate. The scaffolds were characterized by chemico-physical properties (morphology, solid state-FTIR and differential scanning calorimetry (DSC)-surface zeta potential and contact angle), and mechanical properties. Moreover, preclinical properties (cytocompatibility, fibroblast and osteoblast adhesion and proliferation and antimicrobial properties) were assessed. All the scaffolds were based on cylindrical and smooth nanofibers and preserved their nanofibrous structure upon hydration independently of their composition. They possessed a high degree of hydrophilicity and negative zeta potentials in a physiological environment, suitable surface properties to enhance cell adhesion and proliferation and to inhibit bacteria attachment. The scaffold based on gelatin and low molecular weight chitosan proved to be effective in vitro to support both fibroblasts and osteoblasts adhesion and proliferation and to impair the proliferation of Streptococcus mutans and Aggregatibacter actinomycetemcomitans, both pathogens involved in periodontitis.

Nanofibrous cosmetic face mask for transdermal delivery of nano gold: synthesis, characterization, release and zebra fish employed toxicity studies

This study involves the generation of gold nanoparticles (Au NPs) via a novel natural/non-toxic methodology using tea and orange-peel extracts. These were then embedded into a novel blend composed of a polyethylene oxide and gelatin (PEO-Gel) fibre mat. The scanning electron microscopy results indicated that the addition of both collagen (COL) and ascorbic acid (AA) into the PEO-Gel system (PEO-Gel-AA-COL system) enhances the Au NP incorporation into nanofibres leading to a diameter of 164.60 ± 20.95 and 192.43 ± 39.14 nm in contrast to the spraying observed with the Au PEO-Gel system alone. Releasing studies conducted over 30 min indicated that the PEO-Gel-AA-COL-orange peel Au (OpAu) system accounts for a higher content of Au release than the green tea Au (GtAu) NP system where a maximum release could be attained within 10-30 min depending on the amount of Au NPs that have been incorporated. Moreover, the transdermal diffusion studies conducted using Strat membrane indicated that Au NPs from both formulations (PEO-Gel-AA-COL-GtAu nanofibre, PEO-Gel-AA-COL-OpAu nanofibre) have diffused through the stratum corneum and trapped in the dermis and epidermis indicating its transdermal deliverability. Additionally, 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay revealed that nanofibres have similar radical scavenging activity like AA standard. Toxicity evaluation on a zebra fish embryo model confirmed that both GtAu NPs and OpAu NPs do not induce any teratogenic activity and are safe to be used in the range of 1.0-167 µg ml-1.

Novel 3D Hybrid Nanofiber Scaffolds for Bone Regeneration

Development of hybrid scaffolds and their formation methods occupies an important place in tissue engineering. In this paper, a novel method of 3D hybrid scaffold formation is presented as well as an explanation of the differences in scaffold properties, which were a consequence of different crosslinking mechanisms. Scaffolds were formed from 3D freeze-dried gelatin and electrospun poly(lactide-co-glicolide) (PLGA) fibers in a ratio of 1:1 w/w. In order to enhance osteoblast proliferation, the fibers were coated with hydroxyapatite nanoparticles (HAp) using sonochemical processing. All scaffolds were crosslinked using an EDC/NHS solution. The scaffolds' morphology was imaged using scanning electron microscopy (SEM). The chemical composition of the scaffolds was analyzed using several methods. Water absorption and mass loss investigations proved a higher crosslinking degree of the hybrid scaffolds than a pure gelatin scaffold, caused by additional interactions between gelatin, PLGA, and HAp. Additionally, mechanical properties of the 3D hybrid scaffolds were higher than traditional hydrogels. In vitro studies revealed that fibroblasts and osteoblasts proliferated and migrated well on the 3D hybrid scaffolds, and also penetrated their structure during the seven days of the experiment.

Overview of natural hydrogels for regenerative medicine applications

Hydrogels from different materials can be used in biomedical field as an innovative approach in regenerative medicine. Depending on the origin source, hydrogels can be synthetized through chemical and physical methods. Hydrogel can be characterized through several physical parameters, such as size, elastic modulus, swelling and degradation rate. Lately, research is focused on hydrogels derived from biologic materials. These hydrogels can be derived from protein polymers, such as collage, elastin, and polysaccharide polymers like glycosaminoglycans or alginate among others. Introduction of decellularized tissues into hydrogels synthesis displays several advantages compared to natural or synthetic based hydrogels. Preservation of natural molecules such as growth factors, glycans, bioactive cryptic peptides and natural proteins can promote cell growth, function, differentiation, angiogenesis, anti-angiogenesis, antimicrobial effects, and chemotactic effects. Versatility of hydrogels make possible multiple applications and combinations with several molecules on order to obtain the adequate characteristic for each scope. In this context, a lot of molecules such as cross link agents, drugs, grow factors or cells can be used. This review focuses on the recent progress of hydrogels synthesis and applications in order to classify the most recent and relevant matters in biomedical field.

Multi-Functional Electrospun Nanofibers from Polymer Blends for Scaffold Tissue Engineering

Electrospinning and polymer blending have been the focus of research and the industry for their versatility, scalability, and potential applications across many different fields. In tissue engineering, nanofiber scaffolds composed of natural fibers, synthetic fibers, or a mixture of both have been reported. This review reports recent advances in polymer blended scaffolds for tissue engineering and the fabrication of functional scaffolds by electrospinning. A brief theory of electrospinning and the general setup as well as modifications used are presented. Polymer blends, including blends with natural polymers, synthetic polymers, mixture of natural and synthetic polymers, and nanofiller systems, are discussed in detail and reviewed.

Emerging Trends in Information-Driven Engineering of Complex Biological Systems

Synthetic biological systems are used for a myriad of applications, including tissue engineered constructs for in vivo use and microengineered devices for in vitro testing. Recent advances in engineering complex biological systems have been fueled by opportunities arising from the combination of bioinspired materials with biological and computational tools. Driven by the availability of large datasets in the "omics" era of biology, the design of the next generation of tissue equivalents will have to integrate information from single-cell behavior to whole organ architecture. Herein, recent trends in combining multiscale processes to enable the design of the next generation of biomaterials are discussed. Any successful microprocessing pipeline must be able to integrate hierarchical sets of information to capture key aspects of functional tissue equivalents. Micro- and biofabrication techniques that facilitate hierarchical control as well as emerging polymer candidates used in these technologies are also reviewed.

Sonication technique to produce emulsions: The impact of ultrasonic power and gelatin concentration

The production of food emulsions has increased the demand for processes, natural emulsifiers and stabilizers that provide reasonable stability. This study approaches the influence of parameters that affect the stability of emulsions produced by sonication, such as ultrasonic power (150, 225 and 375 W) and gelatin concentration, when producing alginate, potato starch and gelatin stabilized emulsions. The results showed that sonication reduced viscosity, surface charge and improved the interfacial properties of biopolymeric solutions. Emulsions presented visual kinetic stabilization after 7 days of storage. The increase of sonication power reduced particle size but increased flocculation. The use of ultrasonic power at 225 and 375 W and gelatin in a concentration above 0.5% resulted in stable emulsions with smaller particle size, which is desirable for its application in food systems.

Combining Stem Cells and Biomaterial Scaffolds for Constructing Tissues and Cell Delivery

Combining stem cells with biomaterial scaffolds serves as a promising strategy for engineering tissues for both in vitro and in vivo applications. This updated review details commonly used biomaterial scaffolds for engineering tissues from stem cells. We first define the different types of stem cells and their relevant properties and commonly used scaffold formulations. Next, we discuss natural and synthetic scaffold materials typically used when engineering tissues, along with their associated advantages and drawbacks and gives examples of target applications. New approaches to engineering tissues, such as 3D bioprinting, are described as they provide exciting opportunities for future work along with current challenges that must be addressed. Thus, this review provides an overview of the available biomaterials for directing stem cell differentiation as a means of producing replacements for diseased or damaged tissues.

Pneumatospinning of collagen microfibers from benign solvents

INTRODUCTION

Current collagen fiber manufacturing methods for biomedical applications, such as electrospinning and extrusion, have had limited success in clinical translation, partially due to scalability, cost, and complexity challenges. Here we explore an alternative, simplified and scalable collagen fiber formation method, termed 'pneumatospinning,' to generate submicron collagen fibers from benign solvents.

METHODS AND RESULTS

Clinical grade type I atelocollagen from calf corium was electrospun or pneumatospun as sheets of aligned and isotropic fibrous scaffolds. Following crosslinking with genipin, the collagen scaffolds were stable in media for over a month. Pneumatospun collagen samples were characterized using Fourier-transform infrared spectroscopy, circular dichroism, mechanical testing, and scanning electron microscopy showed consistent fiber size and no deleterious chemical changes to the collagen were detected. Pneumatospun collagen had significantly higher tensile strength relative to electrospun collagen, with both processed from acetic acid. Stem cells cultured on pneumatospun collagen showed robust cell attachment and high cytocompatibility. Using DMSO as a solvent, collagen was further co-pneumatospun with poly(d,l-lactide) to produce a blended microfibrous biomaterial.

CONCLUSIONS

Collagen microfibers are shown for the first time to be formed using pneumatospinning, which can be collected as anisotropic or isotropic fibrous grafts. Pneumatospun collagen can be made with higher output, lower cost and less complexity relative to electrospinning. As a robust and rapid method of collagen microfiber synthesis, this manufacturing method has many applications in medical device manufacturing, including those benefiting from anisotropic microstructures, such as ligament, tendon and nerve repair, or for applying microfibrous collagen-based coatings to other materials.

Development of Smart Optical Gels with Highly Magnetically Responsive Bicelles

Hydrogels delivering on-demand tailorable optical properties are formidable smart materials with promising perspectives in numerous fields, including the development of modern sensors and switches, the essential quality criterion being a defined and readily measured response to environmental changes. Lanthanide ion (Ln³⁺)-chelating bicelles are interesting building blocks for such materials because of their magnetic responsive nature. Imbedding these phospholipid-based nanodiscs in a magnetically aligned state in gelatin permits an orientation-dependent retardation of polarized light. The resulting tailorable anisotropy gives the gel a well-defined optical signature observed as a birefringence signal. These phenomena were only reported for a single bicelle-gelatin pair and required high magnetic field strengths of 8 T. Herein, we demonstrate the versatility and enhance the viability of this technology with a new generation of aminocholesterol (Chol-NH₂)-doped bicelles imbedded in two different types of gelatin. The highly magnetically responsive nature of the bicelles allowed to gel the anisotropy at commercially viable magnetic field strengths between 1 and 3 T. Thermoreversible gels with a unique optical signature were generated by exposing the system to various temperature conditions and external magnetic field strengths. The resulting optical properties were a signature of the gel's environmental history, effectively acting as a sensor. Solutions containing the bicelles simultaneously aligning parallel and perpendicular to the magnetic field directions were obtained by mixing samples chelating Tm³⁺ and Dy³⁺. These systems were successfully gelled, providing a material with two distinct temperature-dependent optical characteristics. The high degree of tunability in the magnetic response of the bicelles enables encryption of the gel's optical properties. The proposed gels are viable candidates for temperature tracking of sensitive goods and provide numerous perspectives for future development of tomorrow's smart materials and technologies.

Encapsulation of Bioactive Compound in Electrospun Fibers and Its Potential Application

Electrospinning is a simple and versatile encapsulation technology. Since electrospinning does not involve severe conditions of temperature or pressure or the use of harsh chemicals, it has great potential for effectively entrapping and delivering bioactive compounds. Recently, electrospinning has been used in the food industry to encapsulate bioactive compounds into different biopolymers (carbohydrates and proteins), protecting them from adverse environmental conditions, maintaining the health-promoting properties, and achieving their controlled release. Electrospinning opens a new horizon in food technology with possible commercialization in the near future. This review summarizes the principles and the types of electrospinning processes. The electrospinning of biopolymers and their application in encapsulating of bioactive compounds are highlighted. The existing scope, limitations, and future prospects of electrospinning bioactive compounds are also presented.

Production of Electrospun Fast-Dissolving Drug Delivery Systems with Therapeutic Eutectic Systems Encapsulated in Gelatin

Fast-dissolving delivery systems (FDDS) have received increasing attention in the last years. Oral drug delivery is still the preferred route for the administration of pharmaceutical ingredients. Nevertheless, some patients, e.g. children or elderly people, have difficulties in swallowing solid tablets. In this work, gelatin membranes were produced by electrospinning, containing an encapsulated therapeutic deep-eutectic solvent (THEDES) composed by choline chloride/mandelic acid, in a 1:2 molar ratio. A gelatin solution (30% w/v) with 2% (v/v) of THEDES was used to produce electrospun fibers and the experimental parameters were optimized. Due to the high surface area of polymer fibers, this type of construct has wide applicability. With no cytotoxicity effect, and showing a fast-dissolving release profile in PBS, the gelatin fibers with encapsulated THEDES seem to have promising applications in the development of new drug delivery systems.

Role of solvent-mediated carbodiimide cross-linking in fabrication of electrospun gelatin nanofibrous membranes as ophthalmic biomaterials

Due to their ability to mimic the structure of extracellular matrix, electrospun gelatin nanofibers are promising cell scaffolding materials for tissue engineering applications. However, the hydrophilic gelatin molecules usually need stabilization before use in aqueous physiological environment. Considering that biomaterials cross-linked via film immersion technique may have a more homogeneous cross-linked structure than vapor phase cross-linking, this work aims to investigate the chemical modification of electrospun gelatin nanofibrous membranes by liquid phase carbodiimide in the presence of ethanol/water co-solvents with varying ethanol concentrations ranging from 80 to 99.5vol%. The results of characterization showed that increasing water content in the binary reaction solvent system increases the extent of cross-linking of gelatin nanofibers, but simultaneously promotes the effect of biopolymer swelling and distortion in fiber mat structure. As compared to non-cross-linked counterparts, carbodiimide treated gelatin nanofibrous mats exhibited better thermal and biological stability where the shrinkage temperature and resistance to enzymatic degradation varied in response to ethanol/water solvent composition-mediated generation of cross-links. Irrespective of their cross-linking density, all studied membrane samples did not induce any responses in ocular epithelial cell cultures derived from cornea, lens, and retina. Unlike many other cross-linking agents and/or methods (e.g., excessive vapor phase cross-linking) that may pose a risk of toxicity, our study demonstrated that these nanofibrous materials are well tolerated by anterior segment tissues. These findings also indicate the safety of using ethanol/water co-solvents for chemical cross-linking of gelatin to engineer nanofibrous materials with negligible biological effects. In summary, the present results suggest the importance of solvent-mediated carbodiimide cross-linking in modulating structure-property relationship without compromising in vitro and in vivo biocompatibility of electrospun gelatin nanofibers for future ophthalmic applications.