Cytotoxicity of glutaraldehyde crosslinked collagen/poly(vinyl alcohol) films is by the mechanism of apoptosis

Fabrication of PVA Coatings Applied to Electrospun PLGA Scaffolds to Prevent Postoperative Adhesions

There is currently a demand for anti-adhesive materials that are capable of preventing the formation of intra-abdominal adhesions. In this study, electrospun poly(lactide-co-glycolide) scaffolds were dip-coated in aqueous solutions of polyvinyl alcohol with concentrations of 3 wt.%, 6 wt.% and 9 wt.% to obtain a nontoxic and anti-adhesive biomedical material. The viscosities of the applied 3 wt.%, 6 wt.% and 9 wt.% polyvinyl alcohol solutions were 7.7 mPa∙s, 38.2 mPa∙s and 180.8 mPa∙s, respectively, and increased exponentially. It is shown that increasing the viscosity of the polyvinyl alcohol solution from 6 wt.% to 9 wt.% increases the thickness of the polyvinyl alcohol layer from (3.32 ± 0.97) µm to (8.09 ± 1.43) µm. No pronounced polyvinyl alcohol layer can be observed on samples dip-coated in 3 wt.% PVA solution. Increasing the viscosity of the polyvinyl alcohol solution from 3 wt.% to 9 wt.% increases the mechanical properties of the poly(lactide-co-glycolide) samples by a factor of 1.16-1.45. Cytotoxicity analysis of all samples reveals that none is toxic to 3T3-L1 fibroblast cells. A cell adhesion assay indicates that the anti-adhesion properties increase with increasing viscosity of the polyvinyl alcohol solution and the thickness of the polyvinyl alcohol layer on the poly(lactide-co-glycolide) scaffolds. Fluorescence images of the cells show that as the thickness of the polyvinyl alcohol coating increases, the number of cells decreases, and they do not cover the surface of the samples and form spherical three-dimensional agglomerates. The highest mechanical and anti-adhesion properties are obtained with the poly(lactide-co-glycolide) scaffold sample dip-coated in the 9 wt.% polyvinyl alcohol solution. This is because this sample has the thickest polyvinyl alcohol coating.

Innovative bioinks for 3D bioprinting: Exploring technological potential and regulatory challenges

The field of three dimensional (3D) bioprinting has witnessed significant advancements, with bioinks playing a crucial role in enabling the fabrication of complex tissue constructs. This review explores the innovative bioinks that are currently shaping the future of 3D bioprinting, focusing on their composition, functionality, and potential for tissue engineering, drug delivery, and regenerative medicine. The development of bioinks, incorporating natural and synthetic materials, offers unprecedented opportunities for personalized medicine. However, the rapid technological progress raises regulatory challenges regarding safety, standardization, and long-term biocompatibility. This paper addresses these challenges, examining the current regulatory frameworks and the need for updated guidelines to ensure patient safety and product efficacy. By highlighting both the technological potential and regulatory hurdles, this review offers a comprehensive overview of the future landscape of bioinks in bioprinting, emphasizing the necessity for cross-disciplinary collaboration between scientists, clinicians, and regulatory bodies to achieve successful clinical applications.

Development of Biomimetic Substrates for Limbal Epithelial Stem Cells Using Collagen-Based Films, Hyaluronic Acid, Immortalized Cells, and Macromolecular Crowding

Despite the promising potential of cell-based therapies developed using tissue engineering techniques to treat a wide range of diseases, including limbal stem cell deficiency (LSCD), which leads to corneal blindness, their commercialization remains constrained. This is primarily attributable to the limited cell sources, the use of non-standardizable, unscalable, and unsustainable techniques, and the extended manufacturing processes required to produce transplantable tissue-like surrogates. Herein, we present the first demonstration of the potential of a novel approach combining collagen films (CF), hyaluronic acid (HA), human telomerase-immortalized limbal epithelial stem cells (T-LESCs), and macromolecular crowding (MMC) to develop innovative biomimetic substrates for limbal epithelial stem cells (LESCs). The initial step involved the fabrication and characterization of CF and CF enriched with HA (CF-HA). Subsequently, T-LESCs were seeded on CF, CF-HA, and tissue culture plastic (TCP). Thereafter, the effect of these matrices on basic cellular function and tissue-specific extracellular matrix (ECM) deposition with or without MMC was evaluated. The viability and metabolic activity of cells cultured on CF, CF-HA, and TCP were found to be similar, while CF-HA induced the highest (p < 0.05) cell proliferation. It is notable that CF and HA induced cell growth, whereas MMC increased (p < 0.05) the deposition of collagen IV, fibronectin, and laminin in the T-LESC culture. The data highlight the potential of, in particular, immortalized cells and MMC for the development of biomimetic cell culture substrates, which could be utilized in ocular surface reconstruction following further in vitro, in vivo, and clinical validation of the approach.

Immobilization of Naringinase onto Polydopamine-Coated Magnetic Iron Oxide Nanoparticles for Juice Debittering Applications

Chemical amination of the enzyme was demonstrated to favor immobilization onto polydopamine (PDA)-coated magnetic nanoparticles (MNPs) for the first time, to the best of the author's knowledge. MNPs prepared via hydrothermal synthesis were coated with PDA for the immobilization of naringinase. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy showed that the MNPs were composed mainly of Fe3O4 with an average size of 38.9 nm, and coated with a 15.1 nm PDA layer. Although the specific activities of α-L-rhamnosidase (RAM) and β-D-glucosidase (GLU) of free naringinase decreased with amination, the immobilization yields of the aminated enzyme increased by more than 40% for RAM and more than 10-fold for GLU. The immobilization improved the enzyme's thermal stability (at 50 °C), reaching a half-life of 40.7 and 23.1 h for RAM and GLU activities, respectively. The biocatalyst was successfully used for the debittering of grapefruit juice, detecting a reduction in naringin of 56% after 24 h. These results demonstrate that the enzyme amination is an effective strategy to enhance the immobilization on a PDA coating and could be applied to other enzymes in order to obtain an easily recoverable biocatalyst using a simple immobilization methodology.

Drug-Eluting and Antibacterial Core-Shell Polycaprolactone/Pectin Nanofibers Containing Ti3C2Tx MXene and Medical Herbs for Wound Dressings

Fibrous scaffolds capable of delivering natural drugs and herbs show great promise for tissue regeneration and wound care, particularly in personalized medicine. This study presents the fabrication and characterization of drug-eluting antibacterial core-shell mats composed of polycaprolactone (PCL) and pectin nanofibers produced through coaxial electrospinning. Berberine chloride (BBR), an herbal compound with antineoplastic, anti-inflammatory, antilipidemic, and antidiabetic properties, served as the model drug. Poly(vinyl alcohol) (PVA) was blended with pectin to enhance the mechanical properties of the core fibers. The shell was modified with two-dimensional Ti3C2Tx (MXene) nanosheets and subjected to covalent and ionic cross-linking. Structural analysis confirmed the successful production of bead-free fibers with diameters ranging from 160 to 350 nm, depending on composition. The PCL core fibers were uniformly coated with a pectin/PVA shell approximately 90 nm thick. The inclusion of BBR and MXene increased the fiber diameter. Drug-release kinetics, modeled by using Korsmeyer-Peppas, revealed a two-stage release mechanism. An initial burst release occurred within the first 24 h (kinetic exponent n = 1.36), followed by sustained release over 2 weeks (n = 0.48). The release mechanisms were identified as case-II relaxational release in the first stage, transitioning to quasi-Fickian diffusion in the second. Incorporating MXene into the shell further prolonged drug release. The mechanical strength of the scaffolds improved significantly by a factor of 7 and 4 in wet and dry conditions, respectively. In vitro biocompatibility assays using L929 cells demonstrated excellent cell attachment and compatibility. Additionally, antibacterial tests against Escherichia coli showed that the inclusion of MXene enhanced antibacterial activity by 30%. These results suggest that the functional biocomposite scaffolds hold the potential for developing innovative, drug-eluting wound dressings.

Two Novel Membranes Based on Collagen and Polyphenols for Enhanced Wound Healing

Two novel membranes based on collagen and two polyphenols, taxifolin pentaglutarate (TfG5) and a conjugate of taxifolin with glyoxylic acid (DfTf), were prepared. Fourier transform infrared spectroscopy examination confirmed the preservation of the triple helical structure of collagen. A scanning electron microscopy study showed that both materials had a porous structure. The incorporation of DfTf into the freeze-dried collagen matrix increased the aggregation of collagen fibers to a higher extent than the incorporation of TfG5, resulting in a more compact structure of the material containing DfTf. It was found that NIH/3T3 mouse fibroblasts were attached to, and relatively evenly spread out on, the surface of both newly obtained membranes. In addition, it was shown that the membranes enhanced skin wound healing in rats with a chemical burn induced by acetic acid. The treatment with the materials led to a faster reepithelization and granulation tissue formation compared with the use of other agents (collagen without polyphenols and buffer saline). It was also found that, in the wound tissue, the level of thiobarbituric acid reactive substances (TBARS) was significantly higher and the level of low-molecular-weight SH-containing compounds (RSH) was significantly lower than those in healthy skin, indicating a rise in oxidative stress at the site of injury. The treatment with collagen membranes containing polyphenols significantly decreased the TBARS level and increased the RSH level, suggesting the antioxidant/anti-inflammatory effect of the materials. The membrane containing TfG5 was more effective than other ones (the collagen membrane containing DfTf and collagen without polyphenols). On the whole, the data obtained indicate that collagen materials containing DfTf and TfG5 have potential as powerful therapeutic agents for the treatment of burn wounds.

Synthetic Extracellular Matrix of Polyvinyl Alcohol Nanofibers for Three-Dimensional Cell Culture

An ideal extracellular matrix (ECM) replacement scaffold in a three-dimensional cell (3D) culture should induce in vivo-like interactions between the ECM and cultured cells. Highly hydrophilic polyvinyl alcohol (PVA) nanofibers disintegrate upon contact with water, resulting in the loss of their fibrous morphology in cell cultures. This can be resolved by using chemical crosslinkers and post-crosslinking. A crosslinked, water-stable, porous, and optically transparent PVA nanofibrous membrane (NM) supports the 3D growth of various cell types. The binding of cells attached to the porous PVA NM is low, resulting in the aggregation of cultured cells in prolonged cultures. PVA NMs containing integrin-binding peptides of fibronectin and laminin were produced to retain the blended peptides as cell-binding substrates. These peptide-blended PVA NMs promote peptide-specific cell adherence and growth. Various cells, including epithelial cells, cultured on these PVA NMs form layers instead of cell aggregates and spheroids, and their growth patterns are similar to those of the cells cultured on an ECM-coated PVA NM. The peptide-retained PVA NMs are non-stimulatory to dendritic cells cultured on the membranes. These peptide-retaining PVA NMs can be used as an ECM replacement matrix by providing in vivo-like interactions between the matrix and cultured cells.

Development of Biocompatible Coatings with PVA/Gelatin Hydrogel Films on Vancomycin-Loaded Titania Nanotubes for Controllable Drug Release

This study investigates the utilization of poly(vinyl alcohol) (PVA)/gelatin hydrogel films cross-linked with glutaraldehyde as a novel material to coat the surface of vancomycin-loaded titania nanotubes (TNTs), with a focus on enhancing biocompatibility and achieving controlled vancomycin release. Hydrogel films have emerged as promising candidates in tissue engineering and drug-delivery systems due to their versatile properties. The development of these hydrogel films involved varying the proportions of PVA, gelatin, and glutaraldehyde to achieve the desired properties, including the gel fraction, swelling behavior, biocompatibility, and biodegradation. Among the formulations tested, the hydrogel with a PVA-to-gelatin ratio of 25:75 and 0.2% glutaraldehyde was selected to coat vancomycin-loaded TNTs. The coated TNTs demonstrated slower release of vancomycin compared with the uncoated TNTs. In addition, the coated TNTs demonstrated the ability to promote osteogenesis, as evidenced by increased alkaline phosphatase activity and calcium accumulation. The vancomycin-loaded TNTs coated with hydrogel film demonstrated effectiveness against both E. coli and S. aureus. These findings highlight the potential benefits and therapeutic applications of using hydrogel films to coat implant materials, offering efficient drug delivery and controlled release. This study contributes valuable insights into the development of alternative materials for medical applications, thereby advancing the field of biomaterials and drug delivery systems.

Copper nanoparticles loaded gelatin/ polyvinyl alcohol/ guar gum-based 3D printable multimaterial hydrogel for tissue engineering applications

Hydrogels are becoming increasingly significant in tissue engineering because of their numerous benefits, including biocompatibility, biodegradability, and their ability to provide a supportive structure for cell proliferation. This study presents the synthesis and characterization of a new multimaterial hydrogel with 3D-printing capabilities composed of copper nanoparticle-reinforced gelatin, polyvinyl alcohol (PVA), and guar gum-based biomaterials intended for tissue engineering applications. Combining CuNPs aims to enhance the hydrogel's antibacterial properties, mechanical strength, and bioactivity, which are essential for successful tissue regeneration. Hydrogels are chemically cross-linked with glyoxal and analyzed through different assessments to examine the compressive behavior, surface morphology, sorbing capacity, biocompatibility, thermal stability, and degradation properties. The results demonstrated that including CuNPs significantly improved the hydrogel's compressive modulus (4.18 MPa) for the hydrogel with the CuNPs and provided better antibacterial activity against common pathogens with controlled degradation. All the hydrogels exhibited a lower coefficient of friction, which was below 0.1. In vitro cell culture studies using chondrocytes indicated that the CuNPs-loaded hydrogel supported cell proliferation and growth of chondrogenic genes such as collagen type II (COL2) and aggrecan (ACAN). The biocompatibility and enhanced mechanical properties of the multimaterial hydrogel make it a promising candidate for developing customized, patient-specific tissue engineering scaffolds.

Agar-tragacanth/silk fibroin hydrogel containing Zn-based MOF as a novel nanobiocomposite with biological activity

In this study, a novel nanobiocomposite consisting of agar (Ag), tragacanth gum (TG), silk fibroin (SF), and MOF-5 was synthesized and extensively investigated by various analytical techniques and basic biological assays for potential biomedical applications. The performed Trypan blue dye exclusion assay indicated that the proliferation percentage of HEK293T cells was 71.19%, while the proliferation of cancer cells (K-562 and MCF-7) was significantly lower, at 10.74% and 3.33%. Furthermore, the Ag-TG hydrogel/SF/MOF-5 nanobiocomposite exhibited significant antimicrobial activity against both E. coli and S. aureus strains, with growth inhibition rates of 76.08% and 69.19% respectively. Additionally, the hemolytic index of fabricated nanobiocomposite was found approximately 19%. These findings suggest that the nanobiocomposite exhibits significant potential for application in cancer therapy and wound healing.

The diazirine-mediated photo-crosslinking of collagen improves biomaterial mechanical properties and cellular interactions

In tissue engineering, crosslinking with carbodiimides such as EDC is omnipresent to improve the mechanical properties of biomaterials. However, in collagen biomaterials, EDC reacts with glutamate or aspartate residues, inactivating the binding sites for cellular receptors and rendering collagen inert to many cell types. In this work, we have developed a crosslinking method that ameliorates the rigidity, stability, and degradation rate of collagen biomaterials, whilst retaining key interactions between cells and the native collagen sequence. Our approach relies on the UV-triggered reaction of diazirine groups grafted on lysines, leaving critical amino acid residues intact. Notably, GxxGER recognition motifs for collagen-binding integrins, ablated by EDC crosslinking, were left unreacted, enabling cell attachment, spreading, and colonization on films and porous scaffolds. In addition, our procedure conserves the architecture of biomaterials, improves their resistance to collagenase and cellular contraction, and yields material stiffness akin to that obtained with EDC. Importantly, diazirine-crosslinked collagen can host mesenchymal stem cells, highlighting its strong potential as a substrate for tissue repair. We have therefore established a new crosslinking strategy to modulate the mechanical features of collagen porous scaffolds without altering its biological properties, thereby offering an advantageous alternative to carbodiimide treatment. STATEMENT OF SIGNIFICANCE: This article describes an approach to improve the mechanical properties of collagen porous scaffolds, without impacting collagen's natural interactions with cells. This is significant because collagen crosslinking is overwhelmingly performed using carbodiimides, which results in a critical loss of cellular affinity. By contrast, our method leaves key cellular binding sites in the collagen sequence intact, enabling cell-biomaterial interactions. It relies on the fast, UV-triggered reaction of diazirine with collagen, and does not produce toxic by-products. It also supports the culture of mesenchymal stem cells, a pivotal cell type in a wide range of tissue repair applications. Overall, our approach offers an attractive option for the crosslinking of collagen, a prominent material in the growing field of tissue engineering.

MicroRNA-200c Release from Gelatin-Coated 3D-Printed PCL Scaffolds Enhances Bone Regeneration

The fabrication of clinically relevant synthetic bone grafts relies on combining multiple biodegradable biomaterials to create a structure that supports the regeneration of defects while delivering osteogenic biomolecules that enhance regeneration. MicroRNA-200c (miR-200c) functions as a potent osteoinductive biomolecule to enhance osteogenic differentiation and bone formation; however, synthetic tissue-engineered bone grafts that sustain the delivery of miR-200c for bone regeneration have not yet been evaluated. In this study, we created novel, multimaterial, synthetic bone grafts from gelatin-coated 3D-printed polycaprolactone (PCL) scaffolds. We attempted to optimize the release of pDNA encoding miR-200c by varying gelatin types, concentrations, and polymer crosslinking materials to improve its functions for bone regeneration. We revealed that by modulating gelatin type, coating material concentration, and polymer crosslinking, we effectively altered the release rates of pDNA encoding miR-200c, which promoted osteogenic differentiation in vitro and bone regeneration in a critical-sized calvarial bone defect animal model. We also demonstrated that crosslinking the gelatin coatings on the PCL scaffolds with low-concentration glutaraldehyde was biocompatible and increased cell attachment. These results strongly indicate the potential use of gelatin-based systems for pDNA encoding microRNA delivery in gene therapy and further demonstrate the effectiveness of miR-200c for enhancing bone regeneration from synthetic bone grafts.

"In-situ" formation of elastin-like recombinamer hydrogels with tunable viscoelasticity through efficient one-pot process

Despite the remarkable progress in the generation of recombinant elastin-like (ELR) hydrogels, further improvements are still required to enhance and control their viscoelasticity, as well as limit the use of expensive chemical reagents, time-consuming processes and several purification steps. To alleviate this issue, the reactivity of carboxylic groups from glutamic (E) acid distributed along the hydrophilic block of an amphiphilic ELR (coded as E50I60) with amine groups has been studied through a one-pot amidation reaction in aqueous solutions, for the first time. By means of this approach, immediate conjugation of E50I60 with molecules containing amine groups has been performed with a high yield, as demonstrated by the 1H NMR and MALDI-TOF spectroscopies. This has resulted in the preparation of viscoelastic irreversible hydrogels through the "in-situ" cross-linking of E50I60 with another ELR (coded as VKV24) containing amine groups from lysines (K). The rheology analysis demonstrated that the gelation process takes place following a dual mechanism dependent on the ELR concentration: physical cross-linking of I60 block through the hydrophobic interactions, and covalent cross-linking of E50I60 with VKV24 through the amidation reaction. While the chemical network formed between the hydrophilic E50 block and VKV24 ELR preserves the elasticity of ELR hydrogels, the self-assembly of the I60 block through the hydrophobic interactions provides a tunable physical network. The presented investigation serves as a basis for generating ELR hydrogels with tunable viscoelastic properties promising for tissue regeneration, through an ''in-situ", rapid, scalable, economically and feasible one-pot method.

A Novel Artificial Coronary Plaque to Model Coronary Heart Disease

BACKGROUND

Experimental coronary artery interventions are currently being performed on non-diseased blood vessels in healthy animals. To provide a more realistic pathoanatomical scenario for investigations on novel interventional and surgical therapies, we aimed to fabricate a stenotic lesion, mimicking the morphology and structure of a human atherosclerotic plaque.

METHODS

In an interdisciplinary setting, we engineered a casting mold to create an atherosclerotic plaque with the dimensions to fit in a porcine coronary artery. Oscillatory rheology experiments took place along with long-term stability tests assessed by microscopic examination and weight monitoring. For the implantability in future in vivo setups, we performed a cytotoxicity assessment, inserted the plaque in resected pig hearts, and performed diagnostic imaging to visualize the plaque in its final position.

RESULTS

The most promising composition consists of gelatin, cholesterol, phospholipids, hydroxyapatite, and fine-grained calcium carbonate. It can be inserted in the coronary artery of human-sized pig hearts, producing a local partial stenosis and interacting like the atherosclerotic plaque by stretching and shrinking with the vessel wall and surrounding tissue.

CONCLUSION

This artificial atherosclerotic plaque model works as a simulating tool for future medical testing and could be crucial for further specified research on coronary artery disease and is going to help to provide information about the optimal interventional and surgical care of the disease.

Tissue-engineered and autologous pericardium in congenital heart surgery: comparative histopathological study of human vascular explants

OBJECTIVES

The goal of this histological study was to assess the biocompatibility of vascular patches used in the repair of congenital heart defects.

METHODS

We examined tissue-engineered bovine (n = 7) and equine (n = 7) patches and autologous human pericardium (n = 7), all explanted due to functional issues or follow-up procedures. Techniques like Movat-Verhoeff, von Kossa and immunohistochemical staining were used to analyse tissue composition, detect calcifications and identify immune cells. A semi-quantitative scoring system was implemented to evaluate the biocompatibility aspects, thrombus formation, extent of pannus, inflammation of pannus, cellular response to patch material, patch degradation, calcification and neoadventitial inflammation.

RESULTS

We observed distinct material degradation patterns among types of patches. Bovine patches showed collagen disintegration and exudate accumulation, whereas equine patches displayed edematous swelling and material dissolution. Biocompatibility scores were lower in terms of cellular response, degradation and overall score for human autologous pericardial patches compared to tissue-engineered types. The extent of pannus formation was not influenced by the type of patch. Bovine patches had notable calcifications causing tissue hardening, and foreign body giant cells were more frequently seen in equine patches. Plasma cells were frequently detected in the neointimal tissue of engineered patches.

CONCLUSIONS

Our results confirm the superior biocompatibility of human autologous patches and highlight discernible variations in the changes of patch material and the cellular response to patch material between bovine and equine patches. Our approach implements the semi-quantitative scoring of various aspects of biocompatibility, facilitating a comparative quantitative analysis across all types of patches, despite their inherent differences.

PVA/PVP Nanofibres Incorporated with Ecklonia cava Phlorotannins Exhibit Excellent Cytocompatibility and Accelerate Hyperglycaemic Wound Healing

BACKGROUND

Diabetic foot ulcer (DFU) is a major debilitating complication of diabetes. The lack of effective diabetic wound dressings has been a significant problem in DFU management. In this study, we aim to establish a phlorotannin-incorporated nanofibre system and determine its potential in accelerating hyperglycaemic wound healing.

METHODS

The effective dose of Ecklonia cava phlorotannins (ECP) for hyperglycaemic wound healing was determined prior to phlorotannin nanofibre fabrication using polyvinyl-alcohol (PVA), polyvinylpyrrolidone (PVP), and ECP. Vapour glutaraldehyde was used for crosslinking of the PVA/PVP nanofibres. The phlorotannin nanofibres were characterised, and their safety and cytocompatibility were validated. Next, the wound healing effect of phlorotannin nanofibres was determined with 2D wound scratch assay, whereas immunofluorescence staining of Collagen-I (Col-I) and Cytokeratin-14 (CK-14) was performed in human dermal fibroblasts (HDF) and human epidermal keratinocytes (HEK), respectively.

RESULTS

Our results demonstrated that 0.01 μg/mL ECP significantly improved hyperglycaemic wound healing without compromising cell viability and proliferation. Among all nanofibres, PVA/PVP/0.01 wt% ECP nanofibres exhibited the best hyperglycaemic wound healing effect. They displayed a diameter of 334.7 ± 10.1 nm, a porosity of 40.7 ± 3.3%, and a WVTR of 1718.1 ± 32.3 g/m2/day. Besides, the FTIR spectra and phlorotannin release profile validated the successful vapour glutaraldehyde crosslinking and ECP incorporation. We also demonstrated the potential of phlorotannin nanofibres as a non-cytotoxic wound dressing as they support the viability and proliferation of both HDF and HEK. Furthermore, phlorotannin nanofibres significantly ameliorated the impaired hyperglycaemic wound healing and restored the hyperglycaemic-induced Col-I reduction in HDF.

CONCLUSION

Taken together, our findings show that phlorotannin nanofibres have the potential to be used as a diabetic wound dressing.

Evaluation of Opuntia-carrageenan superporous hydrogel (OPM-CRG SPH) as an effective biomaterial for drug release and tissue scaffold

The process of wound healing involves complex interplay of systems biology, dependent on coordination of various cell types, both intra and extracellular mechanisms, proteins, and signaling pathways. To enhance these interactions, drugs must be administered precisely and continuously, effectively regulating the intricate mechanisms involved in the body's response to injury. Controlled drug delivery systems (DDS) play a pivotal role in achieving this objective. A proficient DDS shields the wound from mechanical, oxidative, and enzymatic stress, against bacterial contamination ensuring an adequate oxygen supply while optimizing the localized and sustained delivery of drugs to target tissue. A pH-sensitive SPH was designed by blending two natural polysaccharides, Opuntia mucilage and carrageenan, using microwave irradiation and optimized according to swelling index at pH 1.2, 7.0, and 8.0 and % porosity. Optimized grade was analyzed for surface hydrophilicity-hydrophobicity using OCA. Analytical characterizations were performed using FTIR, TGA, XRD, DSC, reflecting semicrystalline behavior. Mechanical property confirmed adequate strength. In vitro drug release study with ciprofloxacin-HCL as model drug showed 97.8 % release within 10 h, fitting to the Korsmeyer-Peppas model following diffusion and erosion mechanism. In vitro antimicrobial, anti-inflammatory assays, zebrafish toxicity, and animal studies in mice with SPH concluded it as a novel biomaterial.

Unveiling the Power of Gabapentin-Loaded Nanoceria with Multiple Therapeutic Capabilities for the Treatment of Dry Eye Disease

Dry eye (DE) disease, which is primarily linked to aqueous deficiency, is an escalating health issue worldwide, mainly due to the widespread use of electronic devices. The major obstacles in DE pharmacotherapy include insufficient therapeutic efficacy and low ocular bioavailability. This study presents the development of a ceria-based nanosystem to carry gabapentin (GBT), aiming to offer comprehensive relief from DE symptoms. We prepared multifunctional nanoceria capped with thiolated gelatin followed by cross-linking with glutaraldehyde, yielding a nanocarrier with desirable biocompatibility and antioxidant, anti-inflammatory, antiangiogenic, antiapoptotic, and neuronal protective activities. Specifically, the highly abundant thiol groups on gelatin increased the cellular uptake of the nanocarrier by 2.3-fold and its mucin-binding efficiency by 10-fold, thereby extending ocular retention and amplifying therapeutic activity. Moderate cross-linking of the thiolated gelatin not only enhanced the ocular bioavailability of the nanoceria but also provided slow, degradation-controlled release of GBT to promote the lacrimal stimulation to restore the tear film. In a rabbit model of DE, topical administration of our GBT/nanoceria nanoformulation resulted in comprehensive alleviation of symptoms, including repairing corneal epithelial damage, preserving corneal nerve density, and stimulating tear secretion, demonstrating superior performance in comparison to the free drug. These results underscore the safety and potential of this innovative nanoformulation for DE pharmacotherapy.

Effect of Support Matrix and Crosslinking Agents on Nutritional Properties of Orange Juice during Enzyme Clarification: A Comparative Study

This study investigated the impact of a support matrix and active group on the support to the nutritional properties of orange juice after juice clarification. Pectinase was immobilized on chitosan and aminated silica supports, activated with genipin or glutaraldehyde, and applied for juice clarification. The effects on various juice properties, including reducing sugars, total soluble solids, vitamin C, and phenolic compounds, juice color, and pH, were evaluated. The results revealed that the immobilization on chitosan activated using genipin resulted in the highest biocatalyst activity (1211.21 U·g-1). The juice treatments using the biocatalysts led to turbidity reduction in the juice (up to 90%), with the highest reductions observed in treatments involving immobilized enzyme on chitosan. Importantly, the enzymatic treatments preserved the natural sugar content, total soluble solids, and pH of the juice. Color differences between treated and raw juice samples were especially relevant for those treated using enzymes, with significant differences in L* and b*, showing loss of yellow vivid color. Analysis of phenolic compounds and vitamin C showed no significant alterations after the enzymatic treatment of the raw juice. According to our results, the clarification of orange juice using immobilized enzymes can be a compromise in turbidity reduction and color reduction to maintain juice quality.

Crosslinking strategies in modulating methylcellulose hydrogel properties

Methylcellulose (MC) hydrogels are ideal materials for the design of thermo-responsive platforms capable of exploiting the environment temperature as a driving force to activate their smart transition. However, MC hydrogels usually show reduced stability in an aqueous environment and low mechanical properties, limiting their applications' breadth. A possible approach intended to overcome these limitations is chemical crosslinking, which represents a simple yet effective strategy to modify the MC hydrogels' properties (e.g., physicochemical, mechanical, and biological). In this regard, understanding the selected crosslinking method's role in modulating the MC hydrogels' properties is a key factor in their design. This review offers a perspective on the main MC chemical crosslinking approaches reported in the literature. Three main categories can be distinguished: (i) small molecule crosslinkers, (ii) crosslinking by high-energy radiation, and (iii) crosslinking via MC chemical modification. The advantages and limitations of each approach are elucidated, and special consideration is paid to the thermo-responsive properties after crosslinking towards the development of MC hydrogels with enhanced physical stability and mechanical performance, preserving the thermo-responsive behavior.

Clinical Assessment of Moringa oleifera as a Natural Crosslinker for Enhanced Dentin Bond Durability: A Randomized Controlled Trial

BACKGROUND

Dentin biomodification is a biomimetic approach that strengthens the collagen network, making it less susceptible to enzymatic degradation and improving the durability of bonded restorative materials, using collagen crosslinkers.

OBJECTIVE

This study aimed to assess the effectiveness of Moringa oleifera as a natural crosslinker in improving the clinical success of resin-dentin restorations.

METHOD

A double-blind, controlled, randomized clinical trial was conducted in accordance with Consolidated Standards of Reporting Trials (CONSORT) guidelines, with 50 adult participants with initial carious lesions (ICDAS 4 and 5) enrolled. Participants were randomly assigned to either the experimental group (which received Moringa oleifera as a pretreatment liner) or the control group (standard restorative procedures without a liner). Functional and biological outcomes were assessed at baseline, six months, and 12 months using the FDI criteria. Statistical analysis included Fisher's exact test, Wilcoxon sign rank test, and Mann-Whitney U test.

RESULTS

Both groups exhibited excellent functional properties and marginal adaptation at baseline and six months. At the 12-month mark, the test group displayed clinically better functional properties (97.9%, n=47) compared to the control group (95.8%, n=46), but there was no significant difference (p-value>0.05). Marginal gaps were observed in both groups at six and 12 months (8.3%, n=4), with no significant inter-group variation (p-value>0.05). Radiographic examination showed a harmonious restoration-to-tooth transition. Patient satisfaction remained high, with the test group 4.2% (n=2) and control 2.1% (n=1) reporting minor issues at 12 months, though not statistically significant (p-value>0.05). Postoperative sensitivity was minimal, and tooth integrity was well-preserved.

CONCLUSION

Moringa oleifera, as a pretreatment liner, showed promise in enhancing the clinical success of resin-dentin restorations. Despite minor reported issues, the groups had no statistically significant differences regarding functional and biological outcomes.

The Effect of Chitosan on Physicochemical Properties of Whey Protein Isolate Scaffolds for Tissue Engineering Applications

New scaffolds, based on whey protein isolate (WPI) and chitosan (CS), have been proposed and investigated as possible materials for use in osteochondral tissue repair. Two types of WPI-based hydrogels modified by CS were prepared: CS powder was incorporated into WPI in either dissolved or suspended powder form. The optimal chemical composition of the resulting WPI/CS hydrogels was chosen based on the morphology, structural properties, chemical stability, swelling ratio, wettability, mechanical properties, bioactivity, and cytotoxicity evaluation. The hydrogels with CS incorporated in powder form exhibited superior mechanical properties and higher porosity, whereas those with CS incorporated after dissolution showed enhanced wettability, which decreased with increasing CS content. The introduction of CS powder into the WPI matrix promoted apatite formation, as confirmed by energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) analyses. In vitro cytotoxicity results confirmed the cytocompatibility of CS powder modified WPI hydrogels, suggesting their suitability as cell scaffolds. These findings demonstrate the promising potential of WPI/CS scaffolds for osteochondral tissue repair.

Protein fibers with self-recoverable mechanical properties via dynamic imine chemistry

The manipulation of internal interactions at the molecular level within biological fibers is of particular importance but challenging, severely limiting their tunability in macroscopic performances and applications. It thus becomes imperative to explore new approaches to enhance biological fibers' stability and environmental tolerance and to impart them with diverse functionalities, such as mechanical recoverability and stimulus-triggered responses. Herein, we develop a dynamic imine fiber chemistry (DIFC) approach to engineer molecular interactions to fabricate strong and tough protein fibers with recoverability and actuating behaviors. The resulting DIF fibers exhibit extraordinary mechanical performances, outperforming many recombinant silks and synthetic polymer fibers. Remarkably, impaired DIF fibers caused by fatigue or strong acid treatment are quickly recovered in water directed by the DIFC strategy. Reproducible mechanical performance is thus observed. The DIF fibers also exhibit exotic mechanical stability at extreme temperatures (e.g., -196 °C and 150 °C). When triggered by humidity, the DIFC endows the protein fibers with diverse actuation behaviors, such as self-folding, self-stretching, and self-contracting. Therefore, the established DIFC represents an alternative strategy to strengthen biological fibers and may pave the way for their high-tech applications.

Engineered Bicomponent Adhesives with Instantaneous and Superior Adhesion Performance for Wound Sealing and Healing Applications

Surgical adhesives are playing an important role in wound repair and emergency hemostasis in clinical treatment. However, the development of strong bioglue with rapid in situ adhesion, durable adhesiveness, and flexibility in dynamic and moist physiological environments is still challenging. Herein, a new type of biosynthetic protein bioadhesives with superior adhesion performance is reported by developing a protein aldimine condensation strategy. Lysine‐rich recombinant proteins are designed and massively biosynthesized to instantaneously react with aldehyde cross‐linkers to realize in situ strong adhesion. The obtained bioadhesives show an ultra‐high adhesion strength of ≈101.6 kPa on porcine skin, outperforming extant clinical bioglues. In addition, they possess super biocompatibility, flexibility, biodegradability, and compliance with the tissues. Owing to the strong and instantaneous adhesion properties, the bioadhesives are qualified for dynamic wound closure, facilitating wound repair, and noncompressible hemorrhage. Importantly, they can be industrially encapsulated into custom‐made cartridge delivery tubes at low cost for clinical use. Therefore, biosynthetic bioadhesives have great potential for biological applications and are capable of scaling up to the industrial level for clinical transformation, which will be a successful paradigm for reforming existing clinical products.

Tissue integration patterns of non-crosslinked and crosslinked collagen membranes: an experimental in vivo study

PURPOSE

Non-crosslinked and crosslinked collagen membranes are known to exhibit distinct degradation characteristics, resulting in contrasting orientations of the adjacent tissues and different biological processes. The aim of this study was to conduct a histomorphometric assessment of non-crosslinked and crosslinked collagen membranes regarding neovascularization, tissue integration, tissue encapsulation, and biodegradation.

METHODS

Guided bone regeneration was performed using either a non-crosslinked (BG) or a crosslinked collagen membrane (CM) in 15 beagle dogs, which were euthanized at 4, 8, and 16 weeks (n=5 each) for histomorphometric analysis. The samples were assessed regarding neovascularization, tissue integration, encapsulation, the remaining membrane area, and pseudoperiosteum formation. The BG and CM groups were compared at different time periods using nonparametric statistical methods.

RESULTS

The remaining membrane area of CM was significantly greater than that of BG at 16 weeks; however, there were no significant differences at 4 and 8 weeks. Conversely, the neovascularization score for CM was significantly less than that for BG at 16 weeks. BG exhibited significantly greater tissue integration and encapsulation scores than CM at all time periods, apart from encapsulation at 16 weeks. Pseudoperiosteum formation was observed in the BG group at 16 weeks.

CONCLUSIONS

Although BG membranes were more rapidly biodegraded than CM membranes, they were gradually replaced by connective tissue with complete integration and maturation of the surrounding tissues to form dense periosteum-like connective tissue. Further studies need to be performed to validate the barrier effect of the pseudoperiosteum.

Bioactive Components and Their Activities from Different Parts of Citrus aurantifolia (Christm.) Swingle for Food Development

Citrus aurantifolia is part of the Rutaceae family and belongs to the genus Citrus. It is widely used in food, the chemical industry, and pharmaceuticals because it has a unique flavor and odor. It is nutrient-rich and is beneficial as an antibacterial, anticancer, antioxidant, anti-inflammatory, and insecticide. Secondary metabolites present in C. aurantifolia are what give rise to biological action. Flavonoids, terpenoids, phenolics, limonoids, alkaloids, and essential oils are among the secondary metabolites/phytochemicals discovered in C. aurantifolia. Every portion of the plant's C. aurantifolia has a different composition of secondary metabolites. Environmental conditions such as light and temperature affect the oxidative stability of the secondary metabolites from C. aurantifolia. The oxidative stability has been increased by using microencapsulation. The advantages of microencapsulation are control of the release, solubilization, and protection of the bioactive component. Therefore, the chemical makeup and biological functions of the various plant components of C. aurantifolia must be investigated. The aim of this review is to discuss the bioactive components of C. aurantifolia such as essential oils, flavonoids, terpenoids, phenolic, limonoids, and alkaloids obtained from different parts of the plants and their biological activities such as being antibacterial, antioxidant, anticancer, an insecticide, and anti-inflammatory. In addition, various extraction techniques of the compounds out of different parts of the plant matrix as well as the microencapsulation of the bioactive components in food are also provided.

Influence of formic acid esterified cellulose nanofibrils on compressive strength, resilience and thermal stability of polyvinyl alcohol-xylan hydrogel

Having competitive compressive strength and resilience as well as biocompatibility simultaneously still remains a challenge for composite hydrogels, which is critical if they are aimed for use as functional biomaterials. In the present work, a facile and green method was designed for producing a composite hydrogel based on polyvinyl alcohol (PVA) and xylan with sodium tri-metaphosphate (STMP) as cross-linker, aiming to specially enhance its compressive properties with the aid of eco-friendly produced formic acid esterified cellulose nanofibrils (CNFs). The CNF addition caused a compressive strength decrease of the hydrogels, although the values (2.34-4.57 MPa at a compressive strain of 70 %) were still at a high level among the reported PVA (or polysaccharide) based hydrogels so far. However, the compressive resilience of the hydrogels was enhanced significantly by the CNF addition, with maximal compressive strength retention of 88.49 % and 99.67 % in height recovery after 1000 compression cycles at a strain of 30 %, which reflects the significant influence of CNFs on the compressive recovery ability of the hydrogel. All materials used in the present work are naturally non-toxic with good biocompatible, which makes the synthesized hydrogels with great potential in biomedical applications, e.g., soft-tissue engineering.

Controlled Drug Delivery Device for Cornea Treatment and Novel Method for Its Testing

A new solution for local anesthetic and antibiotic delivery after eye surgery is presented. A contact lens-shaped collagen drug carrier was created and loaded by Levofloxacin and Tetracaine with a riboflavin crosslinked surface layer, thus impeding diffusion. The crosslinking was confirmed by Raman spectroscopy, whereas the drug release was investigated using UV-Vis spectrometry. Due to the surface barrier, the drug gradually releases into the corneal tissue. To test the function of the carrier, a 3D printed device and a new test method for a controlled drug release, which mimics the geometry and physiological lacrimation rate of the human eye, were developed. The experimental setup with simple geometry revealed that the prepared drug delivery device can provide the prolonged release profile of the pseudo-first-order for up to 72 h. The efficiency of the drug delivery was further demonstrated using a dead porcine cornea as a drug recipient, without the need to use live animals for testing. Our drug delivery system significantly surpasses the efficiency of antibiotic and anesthetic eyedrops that would have to be applied approximately 30 times per hour to achieve the same dose as that delivered continuously by our device.

Advanced Polymeric Membranes as Biomaterials Based on Marine Sources Envisaging the Regeneration of Human Tissues

The self-repair capacity of human tissue is limited, motivating the arising of tissue engineering (TE) in building temporary scaffolds that envisage the regeneration of human tissues, including articular cartilage. However, despite the large number of preclinical data available, current therapies are not yet capable of fully restoring the entire healthy structure and function on this tissue when significantly damaged. For this reason, new biomaterial approaches are needed, and the present work proposes the development and characterization of innovative polymeric membranes formed by blending marine origin polymers, in a chemical free cross-linking approach, as biomaterials for tissue regeneration. The results confirmed the production of polyelectrolyte complexes molded as membranes, with structural stability resulting from natural intermolecular interactions between the marine biopolymers collagen, chitosan and fucoidan. Furthermore, the polymeric membranes presented adequate swelling ability without compromising cohesiveness (between 300 and 600%), appropriate surface properties, revealing mechanical properties similar to native articular cartilage. From the different formulations studied, the ones performing better were the ones produced with 3 % shark collagen, 3% chitosan and 10% fucoidan, as well as with 5% jellyfish collagen, 3% shark collagen, 3% chitosan and 10% fucoidan. Overall, the novel marine polymeric membranes demonstrated to have promising chemical, and physical properties for tissue engineering approaches, namely as thin biomaterial that can be applied over the damaged articular cartilage aiming its regeneration.

Cutting Edge Aquatic-Based Collagens in Tissue Engineering

Aquatic-based collagens have attracted much interest due to their great potential application for biomedical sectors, including the tissue engineering sector, as a major component of the extracellular matrix in humans. Their physical and biochemical characteristics offer advantages over mammalian-based collagen; for example, they have excellent biocompatibility and biodegradability, are easy to extract, and pose a relatively low immunological risk to mammalian products. The utilization of aquatic-based collagen also has fewer religious restrictions and lower production costs. Aquatic-based collagen also creates high-added value and good environmental sustainability by aquatic waste utilization. Thus, this study aims to overview aquatic collagen's characteristics, extraction, and fabrication. It also highlights its potential application for tissue engineering and the regeneration of bone, cartilage, dental, skin, and vascular tissue. Moreover, this review highlights the recent research in aquatic collagen, future prospects, and challenges for it as an alternative biomaterial for tissue engineering and regenerative medicines.

Microfluidic Formulation of Topological Hydrogels for Microtissue Engineering

Microfluidics has recently emerged as a powerful tool in generation of submillimeter-sized cell aggregates capable of performing tissue-specific functions, so-called microtissues, for applications in drug testing, regenerative medicine, and cell therapies. In this work, we review the most recent advances in the field, with particular focus on the formulation of cell-encapsulating microgels of small "dimensionalities": "0D" (particles), "1D" (fibers), "2D" (sheets), etc., and with nontrivial internal topologies, typically consisting of multiple compartments loaded with different types of cells and/or biopolymers. Such structures, which we refer to as topological hydrogels or topological microgels (examples including core-shell or Janus microbeads and microfibers, hollow or porous microstructures, or granular hydrogels) can be precisely tailored with high reproducibility and throughput by using microfluidics and used to provide controlled "initial conditions" for cell proliferation and maturation into functional tissue-like microstructures. Microfluidic methods of formulation of topological biomaterials have enabled significant progress in engineering of miniature tissues and organs, such as pancreas, liver, muscle, bone, heart, neural tissue, or vasculature, as well as in fabrication of tailored microenvironments for stem-cell expansion and differentiation, or in cancer modeling, including generation of vascularized tumors for personalized drug testing. We review the available microfluidic fabrication methods by exploiting various cross-linking mechanisms and various routes toward compartmentalization and critically discuss the available tissue-specific applications. Finally, we list the remaining challenges such as simplification of the microfluidic workflow for its widespread use in biomedical research, bench-to-bedside transition including production upscaling, further in vivo validation, generation of more precise organ-like models, as well as incorporation of induced pluripotent stem cells as a step toward clinical applications.

Synthesis and Characterization of a Novel Composite Scaffold Based on Hyaluronic Acid and Equine Type I Collagen

Herein, the synthesis and characterization of a novel composite biopolymer scaffold—based on equine type I collagen and hyaluronic acid—were described by using a reaction in heterogeneous phase. The resulting biomimetic structure was characterized in terms of chemical, physical, and cytotoxicity properties using human-derived lymphocytes and chondrocytes. Firstly, FT-IR data proved a successful reticulation of hyaluronic acid within collagen structure with the appearance of a new peak at a wavenumber of 1735 cm⁻¹ associated with ester carbonyl stretch. TGA and DSC characterizations confirmed different thermal stability of cross-linked scaffolds while morphological analysis by scanning electron microscopy (SEM) suggested the presence of a highly porous structure with open and interconnected void areas suitable for hosting cells. The enzymatic degradation profile confirmed scaffold higher endurance with collagenase as compared with collagen alone. However, it was particularly interesting that the mechanical behavior of the composite scaffold showed an excellent shape memory, especially when it was hydrated, with an improved Young’s modulus of 9.96 ± 0.53 kPa (p ≤ 0.001) as well as a maximum load at 97.36 ± 3.58 kPa compared to the simple collagen scaffold that had a modulus of 1.57 ± 0.08 kPa and a maximum load of 36.91 ± 0.24 kPa. Finally, in vitro cytotoxicity confirmed good product safety with human lymphocytes (viability of 81.92 ± 1.9 and 76.37 ± 1.2 after 24 and 48 h, respectively), whereas excellent gene expression profiles of chondrocytes with a significant upregulation of SOX9 and ACAN after 10 days of culture indicated our scaffold’s ability of preserving chondrogenic phenotype. The described material could be considered a potential tool to be implanted in patients with cartilage defects.

Fucoidan-based nanomaterial and its multifunctional role for pharmaceutical and biomedical applications

Fucoidans are promising sulfated polysaccharides isolated from marine sources that have piqued the interest of scientists in recent years due to their widespread use as a bioactive substance. Bioactive coatings and films, unsurprisingly, have seized these substances to create novel, culinary, therapeutic, and diagnostic bioactive nanomaterials. The applications of fucoidan and its composite nanomaterials have a wide variety of food as well as pharmacological properties, including anti-oxidative, anti-inflammatory, anti-cancer, anti-thrombic, anti-coagulant, immunoregulatory, and anti-viral properties. Blends of fucoidan with other biopolymers such as chitosan, alginate, curdlan, starch, etc., have shown promising coating and film-forming capabilities. A blending of biopolymers is a recommended approach to improve their anticipated properties. This review focuses on the fundamental knowledge and current development of fucoidan, fucoidan-based composite material for bioactive coatings and films, and their biological properties. In this article, fucoidan-based edible bioactive coatings and films expressed excellent mechanical strength that can prolong the shelf-life of food products and maintain their biodegradability. Additionally, these coatings and films showed numerous applications in the biomedical field and contribute to the economy. We hope this review can deliver the theoretical basis for the development of fucoidan-based bioactive material and films.

Fabrication of 3D Gelatin Hydrogel Nanocomposite Impregnated Co-Doped SnO2 Nanomaterial for the Catalytic Reduction of Environmental Pollutants

In the catalytic reduction of various environment pollutants, cobalt-doped tin oxide, i.e., Co-SnO₂ intercalated gelatin (GL) hydrogel nanocomposite was prepared via direct mixing of Co-SnO₂ doped with GL. Then, it was crosslinked internally using formaldehyde within a viscous solution of gelatin polymer, which led to the formation of GL/Co-SnO₂ hydrogel nanocomposite. GL/Co-SnO₂ hydrogel nanocomposite was fully characterized by using field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR). The FESEM images indicate that the Co-SnO₂ composite has a spherical structure on the GL matrix while EDX elucidates the elemental composition of each atom in the crosslinked GL/Co-SnO₂ hydrogel nanocomposite. The GL/Co-SnO₂ nanocomposite was checked for the reduction of various pollutants, including 2-nitro-phenol (2-NP), 2,6-dinitro-phenol (2,6-DNP), 4-nitro-phenol (4-NP), Congo red (CR), and methyl orange (MO) dyes with a strong sodium borohydride (NaBH₄) reducing agent. The GL/Co-SnO₂ nanocomposite synergistically reduced the MO in the presence of the reducing agent with greater reduction rate of 1.036 min⁻¹ compared to other dyes. The reduction condition was optimized by changing various parameters, such as the catalyst amount, dye concentration, and the NaBH₄ amount. Moreover, the GL/Co-SnO₂ nanocomposite catalyst can be easily recovered, is recyclable, and revealed minimal loss of nanomaterials.

Origin of critical nature and stability enhancement in collagen matrix based biomaterials: Comprehensive modification technologies

Collagen is the most abundant protein in animals and one of the most important extracellular matrices that chronically plays an important role in biomaterials. However, the major concern about native collagen is the lack of its thermal stability and weak resistance to proteolytic degradation. Currently, a series of modification technologies have been explored for critical nature and stability enhancement in collagen matrix-based biomaterials, and prosperously large-scale progress has been achieved. The establishment of covalent bonds among collagen noumenon has been verified assuringly to have pregnant influences on its physicochemical properties and biological properties, enlightening to discuss the disparate modification technologies on specific effects on the multihierarchical structures and pivotal performances of collagen. In this review, various existing modification methods were classified from a new perspective, scilicet whether to introduce exogenous substances, to reveal the basic scientific theories of collagen modification. Understanding the role of modification technologies in the enhancement of collagen performance is crucial for developing novel collagen-based biomaterials. Moreover, the different modification effects caused by the interaction sites between the modifier and collagen, and the structure-activity relationship between the structure of the modifier and the properties of collagen were reviewed.

Advancements in Extracellular Matrix-Based Biomaterials and Biofabrication of 3D Organotypic Skin Models

Over the last decades, three-dimensional (3D) organotypic skin models have received enormous attention as alternative models to in vivo animal models and in vitro two-dimensional assays. To date, most organotypic skin models have an epidermal layer of keratinocytes and a dermal layer of fibroblasts embedded in an extracellular matrix (ECM)-based biomaterial. The ECM provides mechanical support and biochemical signals to the cells. Without advancements in ECM-based biomaterials and biofabrication technologies, it would have been impossible to create organotypic skin models that mimic native human skin. In this review, the use of ECM-based biomaterials in the reconstruction of skin models, as well as the study of complete ECM-based biomaterials, such as fibroblasts-derived ECM and decellularized ECM as a better biomaterial, will be highlighted. We also discuss the benefits and drawbacks of several biofabrication processes used in the fabrication of ECM-based biomaterials, such as conventional static culture, electrospinning, 3D bioprinting, and skin-on-a-chip. Advancements and future possibilities in modifying ECM-based biomaterials to recreate disease-like skin models will also be highlighted, given the importance of organotypic skin models in disease modeling. Overall, this review provides an overview of the present variety of ECM-based biomaterials and biofabrication technologies available. An enhanced organotypic skin model is expected to be produced in the near future by combining knowledge from previous experiences and current research.

Prevention of postoperative adhesion with a colloidal gel based on decyl group-modified Alaska pollock gelatin microparticles

Postoperative adhesion, bonding of the abdominal wall to damaged organs, causes severe complications after abdominal surgery. Despite the availability of physical barriers (i.e., solutions, films, and hydrogels), adhesion prevention materials that are a single-substance system with stability in wet tissue and ease of use have not been reported. Here, we report a microparticle based, sprayable adhesion prevention material comprising decyl group modified Alaska pollock gelatin (C10-ApGltn). C10-ApGltn microparticles (C10-MPs) were prepared by a coacervation method, freeze drying, and thermal crosslinking. The C10-MPs adhered to and formed a colloidal gel layer on intestinal serosal tissue by hydration without any crosslinking agents. After hydration of the C10-MPs, the resulting colloidal gel layer did not adhere to other tissues. Additionally, the C10-MP colloidal gel layer formed on the stomach serosal tissue showed stability when submersed in saline for 2 days. The colloidal gel layer also showed tissue followability. An in vivo rat adhesion model revealed that C10-MP colloidal gel layer on the cecum and abdominal wall defects effectively reduced postoperative adhesion and induced tissue remodeling, including re-mesothelialization. Therefore, C10-MPs are a potential anti-adhesion material for preventing postoperative adhesion. STATEMENT OF SIGNIFICANCE: We evaluated the postoperative adhesion prevention ability of a colloidal gel based on decyl group modified Alaska pollock gelatin (ApGltn) microparticles (C10-MPs). These microparticles are sprayable and form a colloidal gel with only hydration on the gastrointestinal tissue. We revealed that the modification of the decyl group into ApGltn improved the stability of C10-MP colloidal gel on the tissue by hydrophobic interaction in the in-vitro experiments. The gel prevented postoperative adhesion by being a physical barrier in the in-vivo rat adhesion model.

Marine origin biomaterials using a compressive and absorption methodology as cell-laden hydrogel envisaging cartilage tissue engineering

In the recent decade, marine origin products have been growingly studied as building blocks complying with the constant demand of the biomedical sector regarding the development of new devices for Tissue Engineering and Regenerative Medicine (TERM). In this work, several combinations of marine collagen-chitosan-fucoidan hydrogel were formed using a newly developed eco-friendly compressive and absorption methodology to produce hydrogels (CAMPH), which consists of compacting the biopolymers solution while removing the excess of water. The hydrogel formulations were prepared by blending solutions of 5% collagen from jellyfish and/or 3% collagen from blue shark skin, with solutions of 3% chitosan from squid pens and solutions of 10% fucoidan from brown algae, at different ratios. The biopolymer physico-chemical characterization comprised Amino Acid analysis, ATR-FTIR, CD, SDS-PAGE, ICP, XRD, and the results suggested the shark/jellyfish collagen(s) conserved the triple helical structure and had similarities with type I and type II collagen, respectively. The studied collagens also contain a denaturation temperature of around 30-32 °C and a molecular weight between 120 and 125 kDa. Additionally, the hydrogel properties were determined by rheology, water uptake ability, degradation rate, and SEM, and the results showed that all formulations had interesting mechanical (strong viscoelastic character) and structural stability properties, with a significant positive highlight in the formulation of H₃ (blending all biopolymers, i.e., 5% collagen from jellyfish, 3% collagen from skin shark, 3% chitosan and 10% of fucoidan) in the degradation test, that shows a mass loss around 18% over the 30 days, while the H₁ and H₂, present a mass loss of around 35% and 44%, respectively. Additionally, the in vitro cellular assessments using chondrocyte cells (ATDC5) in encapsulated state revealed, for all hydrogel formulations, a non-cytotoxic behavior. Furthermore, Live/Dead assay and Phalloidin/DAPI staining, to assess the cytoskeletal organization, proved that the hydrogels can provide a suitable microenvironment for cell adhesion, viability, and proliferation, after being encapsulated. Overall, the results show that all marine collagen (jellyfish/shark)-chitosan-fucoidan hydrogel formulations provide a good structural architecture and microenvironment, highlighting the H₃ biomaterial due to containing more polymers in their composition, making it suitable for biomedical articular cartilage therapies.

Liquid-type plasma-controlled in situ crosslinking of silk-alginate injectable gel displayed better bioactivities and mechanical properties

Silk is a promising biomaterial for injectable hydrogel, but its long-gelation time and cytotoxic crosslinking methods are the main obstacles for clinical application. Here, we purpose a new in situ crosslinking technique of silk-alginate (S-A) injectable hydrogel using liquid-type non-thermal atmospheric plasma (LTP) in vocal fold (VF) wound healing. We confirmed that LTP induces the secondary structure of silk in a dose-dependent manner, resulting in improved mechanical properties. Significantly increased crosslinking of silk was observed with reduced gelation time. Moreover, controlled release of nitrate, an LTP effectors, from LTP-treated S-A hydrogel was detected over 7 days. In vitro experiments regarding biocompatibility showed activation of fibroblasts beyond the non-cytotoxicity of LTP-treated S-A hydrogels. An in vivo animal model of VF injury was established in New Zealand White rabbits. Full-thickness injury was created on the VF followed by hydrogel injection. In histologic analyses, LTP-treated S-A hydrogels significantly reduced a scar formation and promoted favorable wound healing. Functional analysis using videokymography showed eventual viscoelastic recovery. The LTP not only changes the mechanical structures of a hydrogel, but also has sustained biochemical effects on the damaged tissue due to controlled release of LTP effectors, and that LTP-treated S-A hydrogel can be used to enhance wound healing after VF injury.

A PEGylation method of fabricating bioprosthetic heart valves based on glutaraldehyde and 2-amino-4-pentenoic acid co-crosslinking with improved antithrombogenicity and cytocompatibility

With the development of diagnostic techniques, the incidence of bioprosthetic heart valve thrombosis (BHVT) is found to be seriously underestimated. Developing bioprosthetic heart valves (BHVs) that have good hemocompatibility without sacrificing other properties such as hydrodynamics and durability will be an effective strategy to alleviate BHVT. In this study, we developed a PEGylation method by co-crosslinking and subsequent radical polymerization. 2-amino-4-pentenoic acid was used to introduce carbon-carbon double bonds for glutaraldehyde crosslinked pericardia. Then poly (ethylene glycol) diacrylate (PEGDA) was immobilized on pericardia by radical polymerization. A comprehensive evaluation of the modified pericardia was performed including structural characterization, hemocompatibility, cytocompatibility, mechanical properties, component stability, hydrodynamic performance and durability of the BHVs. The modified pericardia significantly reduced platelet adhesion by more than 75% compared with traditional glutaraldehyde crosslinked pericardia. Cell viability in the modified pericardia group was nearly 5-fold higher than that in glutaraldehyde crosslinked pericardia. The hydrodynamic performance met the requirements of ISO 5840-3 under physiological aortic valve conditions and its durability was proved after 200 million cycles of accelerated fatigue test. In conclusion, PEGDA modified pericardia exhibited improved antithrombogenicity and cytocompatibility properties compared with glutaraldehyde crosslinked pericardia. STATEMENT OF SIGNIFICANCE: Bioprosthetic valve (BHV) implantation requires BHV to be structurally stable as well as biocompatible in vivo. Traditional glutaraldehyde crosslinking method prepared BHV suffers from severe cytotoxicity, thrombosis, and calcification. BHV modification methods that have simultaneously improved structural stability and biocompatibility were rarely reported. Here, we proposed a PEGylation method for BHV based on co-crosslinking strategy that could improve its structural stability as well as hemocompatibility. We take the advantage of high efficiency of glutaraldehyde crosslinking and demonstrate the feasibility and superiority of the PEGylated strategy, offering a promising option in glutaraldehyde-based BHV fabrication in the future.

Protein materials as sustainable non- and minimally invasive strategies for biomedical applications

Protein-based materials have found applications in a wide range of biomedical fields because of their biocompatibility, biodegradability and great versatility. Materials of different physical forms including particles, hydrogels, films, fibers and microneedles have been fabricated e.g. as carriers for drug delivery, factors to promote wound healing and as structural support for the generation of new tissue. This review aims at providing an overview of the current scientific knowledge on protein-based materials, and selected preclinical and clinical studies will be reviewed in depth as examples of the latest progress within the field of protein-based materials, specifically focusing on non- and minimally invasive strategies mainly for topical application.

The effect of hard-type crosslinked hyaluronic acid with particulate bone substitute on bone regeneration: positive or negative?

Purpose

Methods

Results

Conclusions

Functionalization of Electrospun Polycaprolactone Scaffolds with Matrix-Binding Osteocyte-Derived Extracellular Vesicles Promotes Osteoblastic Differentiation and Mineralization

Synthetic polymeric materials have demonstrated great promise for bone tissue engineering based on their compatibility with a wide array of scaffold-manufacturing techniques, but are limited in terms of the bioactivity when compared to naturally occurring materials. To enhance the regenerative properties of these materials, they are commonly functionalised with bioactive factors to guide growth within the developing tissue. Extracellular matrix vesicles (EVs) play an important role in facilitating endochondral ossification during long bone development and have recently emerged as important mediators of cell-cell communication coordinating bone regeneration, and thus represent an ideal target to enhance the regenerative properties of synthetic scaffolds. Therefore, in this paper we developed tools and protocols to enable the attachment of MLO-Y4 osteocyte-derived EVs onto electrospun polycaprolactone (PCL) scaffolds for bone repair. Initially, we optimize a method for the functionalization of PCL materials with collagen type-1 and fibronectin, inspired by the behaviour of matrix vesicles during endochondral ossification, and demonstrate that this is an effective method for the adhesion of EVs to the material surface. We then used this functionalization process to attach osteogenic EVs, collected from mechanically stimulated MLO-Y4 osteocytes, to collagen-coated electrospun PCL scaffolds. The EV-functionalized scaffold promoted osteogenic differentiation (measured by increased ALP activity) and mineralization of the matrix. In particular, EV-functionalised scaffolds exhibited significant increases in matrix mineralization particularly at earlier time points compared to uncoated and collagen-coated controls. This approach to matrix-based adhesion of EVs provides a mechanism for incorporating vesicle signalling into polyester scaffolds and demonstrates the potential of osteocyte derived EVs to enhance the rate of bone tissue regeneration.

The Effect of the PVA/Chitosan/Citric Acid Ratio on the Hydrophilicity of Electrospun Nanofiber Meshes

In this study, scaffolds were prepared via an electrospinning method for application in oral cavities. The hydrophilicity of the fiber mesh is of paramount importance, as it promotes cell spreading; however, the most commonly used polyvinyl alcohol (PVA) and other hydrophilic fiber meshes immediately disintegrate in aqueous media. In contrast, the excessive hydrophobicity of the scaffolds already inhibits cells adhesion on the surface. Therefore, the hydrophilicity of the fiber meshes needed to be optimized. Scaffolds with different polyvinyl alcohol (PVA)/chitosan/citric acid ratios were prepared. The addition of chitosan and the heat initiated cross-linkage of the polymers via citric acid enhanced the scaffolds' hydrophobicity. The optimization of this property could be followed by contact angle measurements, and the increased number of cross-linkages were also supported by IR spectroscopy results. The fibers' physical parameters were monitored via low-vacuum scanning electron microscopy (SEM) and atomic force microscopy (AFM). As biocompatibility is essential for dental applications, Alamar Blue assay was used to prove that meshes do not have any negative effects on dental pulp stem cells. Our results showed that the optimization of the fiber nets was successful, as they will not disintegrate in intraoral cavities during dental applications.