Fish Collagen and Hydroxyapatite Reinforced Poly(lactide-co-glycolide) Fibrous Membrane for Guided Bone Regeneration

Directed Assembly of Elastic Fibers via Coacervate Droplet Deposition on Electrospun Templates

Elastic fibers provide critical elasticity to the arteries, lungs, and other organs. Elastic fiber assembly is a process where soluble tropoelastin is coacervated into liquid droplets, cross-linked, and deposited onto and into microfibrils. While much progress has been made in understanding the biology of this process, questions remain regarding the timing of interactions during assembly. Furthermore, it is unclear to what extent fibrous templates are needed to guide coacervate droplets into the correct architecture. The organization and shaping of coacervate droplets onto a fiber template have never been previously modeled or employed as a strategy for shaping elastin fiber materials. Using an in vitro system consisting of elastin-like polypeptides (ELPs), genipin cross-linker, electrospun polylactic-co-glycolic acid (PLGA) fibers, and tannic acid surface coatings for fibers, we explored ELP coacervation, cross-linking, and deposition onto fiber templates. We demonstrate that integration of coacervate droplets into a fibrous template is primarily influenced by two factors: (1) the balance of coacervation and cross-linking and (2) the surface energy of the fiber templates. The success of this integration affects the mechanical properties of the final fiber network. Our resulting membrane materials exhibit highly tunable morphologies and a range of elastic moduli (0.8-1.6 MPa) comparable to native elastic fibers.

Bioinspired core-shell nanofiber drug-delivery system modulates osteogenic and osteoclast activity for bone tissue regeneration

Osteogenic-osteoclast coupling processes play a crucial role in bone regeneration. Recently, strategies that focus on multi-functionalized implant surfaces to enhance the healing of bone defects through the synergistic regulation of osteogenesis and osteoclastogenesis is still a challenging task in the field of bone tissue engineering. The aim of this study was to create a dual-drug release-based core-shell nanofibers with the intent of achieving a time-controlled release to facilitate bone regeneration. We fabricated core-shell P/PCL nanofibers using coaxial electrospinning, where alendronate (ALN) was incorporated into the core layer and hydroxyapatite (HA) into shell. The surface of the nanofiber construct was further modified with mussel-derived polydopamine (PDA) to induce hydrophilicity and enhance cell interactions. Surface characterizations confirmed the successful synthesis of PDA@PHA/PCL-ALN nanofibers endowed with excellent mechanical strength (20.02 ± 0.13 MPa) and hydrophilicity (22.56°), as well as the sustained sequential release of ALN and Ca ions. In vitro experiments demonstrated that PDA-functionalized core-shell PHA/PCL-ALN scaffolds possessed excellent cytocompatibility, enhanced cell adhesion and proliferation, alkaline phosphatase activity and osteogenesis-related genes. In addition to osteogenesis, the engineered scaffolds also significantly reduced osteoclastogenesis, such as tartrate-resistant acid phosphatase activity and osteoclastogenesis-related gene expression. After 12-week of implantation, it was observed that PDA@PHA/PCL-ALN nanofiber scaffolds, in a rat cranial defect model, significantly promoted bone repair and regeneration. Microcomputed tomography, histological examination, and immunohistochemical analysis collectively demonstrated that the PDA-functionalized core-shell PHA/PCL-ALN scaffolds exhibited exceptional osteogenesis-inducing and osteoclastogenesis-inhibiting effects. Finally, it may be concluded from our results that the bio-inspired surface-functionalized multifunctional, biomimetic and controlled release core-shell nanofiber provides a promising strategy to facilitate bone healing.

A chitosan-coated PCL/nano-hydroxyapatite aerogel integrated with a nanofiber membrane for providing antibacterial activity and guiding bone regeneration

A guided bone regeneration (GBR) membrane can act as a barrier to prevent the invasion and interference from foreign soft tissues, promoting infiltration and proliferation of osteoblasts in the bone defect area. Herein, a composite scaffold with dual functions of osteogenesis and antibacterial effects was prepared for GBR. A polycaprolactone (PCL)/nano-hydroxyapatite (n-HA) aerogel produced by electrospinning and freeze-drying techniques was fabricated as the loose layer of the scaffold, while a PCL nanofiber membrane was used as the dense layer. Chitosan (CS) solution served as a middle layer to provide mechanical support and antibacterial effects between the two layers. Morphological results showed that the loose layer had a porous structure with n-HA successfully dispersed in the aerogels, while the dense layer possessed a sufficiently dense structure. In vitro antibacterial experiments illustrated that the CS solution in the middle layer stabilized the scaffold structure and endowed the scaffold with good antibacterial properties. The cytocompatibility results indicated that both fibroblasts and osteoblasts exhibited superior cell activity on the dense and loose layers, respectively. In particular, the dense layer made of nanofibers could work as a barrier layer to inhibit the infiltration of fibroblasts into the loose layer. In vitro osteogenesis analysis suggested that the PCL/n-HA aerogel could enhance the bone induction ability of bone mesenchymal stem cells, which was confirmed by the increased expression of the alkaline phosphatase activity. The loose structure facilitated the infiltration and migration of bone mesenchymal stem cells for better osteogenesis. In summary, such a composite scaffold exhibited excellent osteogenic and antibacterial properties as well as the barrier effect, thus holding promising potential for use as GBR materials.

Advances in guided bone regeneration membranes: a comprehensive review of materials and techniques

Guided tissue/bone regeneration (GTR/GBR) is a widely used technique in dentistry to facilitate the regeneration of damaged bone and tissue, which involves guiding materials that eventually degrade, allowing newly created tissue to take its place. This comprehensive review the evolution of biomaterials for guided bone regeneration that showcases a progressive shift from non-resorbable to highly biocompatible and bioactive materials, allowing for more effective and predictable bone regeneration. The evolution of biomaterials for guided bone regeneration GTR/GBR has marked a significant progression in regenerative dentistry and maxillofacial surgery. Biomaterials used in GBR have evolved over time to enhance biocompatibility, bioactivity, and efficacy in promoting bone growth and integration. This review also probes into several promising fabrication techniques like electrospinning and latest 3D printing fabrication techniques, which have shown potential in enhancing tissue and bone regeneration processes. Further, the challenges and future direction of GTR/GBR are explored and discussed.

Triple-Hybrid BioScaffold Based on Silk Fibroin, Chitosan, and nano-Biphasic Calcium Phosphates: Preparation, Characterization of Physiochemical and Biopharmaceutical Properties

Bioscaffolds, which promote cell regeneration and restore tissues' functions, have emerged as significant need in clinic. The hybrid of several biomaterials in a bioscaffold renders clinically advanced and relevant properties for applications yet add challenges in cost efficiency, production, and clinical investigation. This study proposes a facile and sustainable method to formulate a triple-hybrid bioscaffold based on Vietnamese cocoon origin Silk Fibroin, Chitosan, and nano-Biphasic Calcium Phosphates (nano-BCP) that can be easily molded, has high porosity (55-80%), and swelling capacity that facilitates cell proliferation and nutrient diffusion. Notably, their mechanical properties, in particular compressive strength, can easily be tuned in a range from 50 - 200 kPa by changing the amount of nano-BCP addition, which is comparable to the successful precedents for productive cell regeneration. The latter parts investigate the biopharmaceutical properties of a representative bioscaffold, including drug loading and release studies with two kinds of active compounds, salmon calcitonin and methylprednisolone. Furthermore, the bioscaffold is highly biocompatible as the results of hemocompatibility and hemostasis tests, as well as ovo chick chorioallantoic membrane investigation. The findings of the study suggest the triple-hybrid scaffold as a promising platform for multi-functional drug delivery and bone defect repair.

M2 macrophage-derived exosome-functionalized topological scaffolds regulate the foreign body response and the coupling of angio/osteoclasto/osteogenesis

Designing scaffolds that can regulate the innate immune response and promote vascularized bone regeneration holds promise for bone tissue engineering. Herein, electrospun scaffolds that combined physical and biological cues were fabricated by anchoring reparative M2 macrophage-derived exosomes onto topological pore structured nanofibrous scaffolds. The topological pore structure of the fiber and the immobilization of exosomes increased the nanoscale roughness and hydrophilicity of the fibrous scaffold. In vitro cell experiments showed that exosomes could be internalized by target cells to promote cell migration, tube formation, osteogenic differentiation, and anti-inflammatory macrophage polarization. The activation of fibrosis, angiogenesis, and macrophage was elucidated during the exosome-functionalized fibrous scaffold-mediated foreign body response (FBR) in subcutaneous implantation in mice. The exosome-functionalized nanofibrous scaffolds also enhanced vascularized bone formation in a critical-sized rat cranial bone defect model. Importantly, histological analysis revealed that the biofunctional scaffolds regulated the coupling effect of angiogenesis, osteoclastogenesis, and osteogenesis by stimulating type H vessel formation. This study elaborated on the complex processes within the cell microenvironment niche during fibrous scaffold-mediated FBR and vascularized bone regeneration to guide the design of implants or devices used in orthopedics and maxillofacial surgery. STATEMENT OF SIGNIFICANCE: How to design scaffold materials that can regulate the local immune niche and truly achieve functional vascularized bone regeneration still remain an open question. Here, combining physical and biological cues, we proposed new insight to cell-free and growth factor-free therapy, anchoring reparative M2 macrophage-derived exosomes onto topological pore structured nanofibrous scaffolds. The exosomes functionalized-scaffold system mitigated foreign body response, including excessive fibrosis, tumor-like vascularization, and macrophage activation. Importantly, the biofunctional scaffolds regulated the coupling effect of angiogenesis, osteoclastogenesis, and osteogenesis by stimulating type H vessel formation.

A biomimetic in situ mineralization ECM composite scaffold to promote endogenous bone regeneration

Bone tissue engineering scaffolds constructed from single-component organic materials have inherent limitations. Inspired by the hierarchical structure of physiological natural bone hard tissues, our research explores the construction of organic-inorganic composite scaffold for bone regeneration. In this study, we used a natural and readily obtainable extracellular matrix (ECM) material, i.e., decellularized small intestinal submucosa (SIS), to build the organic component of a phosphorylated hydroxyapatite nanocrystal-containing composite scaffold (nHA@SIS). Guided by polymer-induced liquid-precursor theory, we introduced a soluble inorganic mineralization solution to achieve an inorganic component of nHA@SIS. Using in situ mineralization, we successfully formed inorganic component within SIS and constructed nHA@SIS composite scaffold. We analyzed the physicochemical properties and the osteogenic role of nHA@SIS via a series of in vitro and in vivo studies. Compared with SIS scaffold, the nHA@SIS possessed suitable physicochemical properties, maintained the excellent cell activity of SIS and better guided reorganization of the cell skeleton, thereby achieving superior osteoconductivity and maintaining osteoinductivity at the protein and gene levels. Furthermore, the rat cranial defect area in the nHA@SIS scaffold group was mostly repaired after 12 weeks of implantation, with a larger amount of higher-density new bone tissue being visible at the edge and center than SIS and blank control group. This significantly improved in vivo osteogenic ability indicated the great potential of nHA@SIS for bone tissue engineering applications.

Current and Expected Trends for the Marine Chitin/Chitosan and Collagen Value Chains

Chitin/chitosan and collagen are two of the most important bioactive compounds, with applications in the pharmaceutical, veterinary, nutraceutical, cosmetic, biomaterials, and other industries. When extracted from non-edible parts of fish and shellfish, by-catches, and invasive species, their use contributes to a more sustainable and circular economy. The present article reviews the scientific knowledge and publication trends along the marine chitin/chitosan and collagen value chains and assesses how researchers, industry players, and end-users can bridge the gap between scientific understanding and industrial applications. Overall, research on chitin/chitosan remains focused on the compound itself rather than its market applications. Still, chitin/chitosan use is expected to increase in food and biomedical applications, while that of collagen is expected to increase in biomedical, cosmetic, pharmaceutical, and nutritional applications. Sustainable practices, such as the reuse of waste materials, contribute to strengthen both value chains; the identified weaknesses include the lack of studies considering market trends, social sustainability, and profitability, as well as insufficient examination of intellectual property rights. Government regulations, market demand, consumer preferences, technological advancements, environmental challenges, and legal frameworks play significant roles in shaping both value chains. Addressing these factors is crucial for seizing opportunities, fostering sustainability, complying with regulations, and maintaining competitiveness in these constantly evolving value chains.

Accelerated Bone Reconstruction by the Yoda1 Bilayer Membrane via Promotion of Osteointegration and Angiogenesis

Guided bone regeneration membranes are widely used to prevent fibroblast penetration and facilitate bone defect repair by osteoblasts. However, the current clinically available collagen membranes lack bone induction and angiogenic capacities, exhibiting limited bone regeneration. The mechanically sensitive channel, Piezo1, which is activated by Yoda1, has been reported to play crucial roles in osteogenesis and angiogenesis. Nevertheless, the application of Yoda1 alone is unsustainable to maintain this activity. Therefore, this study fabricates a Yoda1-loading bilayer membrane using electrospinning technology. Its inner layer in contact with the bone defect is composed of vertically aligned fibers, which regulate the proliferation and differentiation of cells, release Yoda1, and promote bone regeneration. Its outer layer in contact with the soft tissue is dense with oriented fibers by UV cross-linking, mainly preventing fibroblast infiltration and inhibiting the immune response. Furthermore, the loaded Yoda1 affects osteogenesis and angiogenesis via the Piezo1/RhoA/Rho-associated coiled-coil-containing protein kinase 1/Yes1-associated transcriptional regulator signaling pathway. The results reveal that the Yoda1 bilayer membrane is efficient and versatile in accelerating bone regeneration, suggesting its potential as a novel therapeutic agent for various clinical issues.

Incorporation of Magnesium and Zinc Metallic Particles in PLGA Bi-layered Membranes with Sequential Ion Release for Guided Bone Regeneration

Guided bone regeneration (GBR) membranes are commonly used for periodontal tissue regeneration. Due to the complications of existing GBR membranes, the design of bioactive membranes is still relevant. GBR membranes with an asymmetric structure can accommodate the functional requirements of different interfacial tissues. Here, poly(lactic acid-glycolic acid) (PLGA) was selected as the matrix for preparing a bi-layered membrane with both dense and porous structure. The dense layer for blocking soft tissues was incorporated with zinc (Zn) particles, while the porous layer for promoting bone regeneration was co-incorporated with magnesium (Mg) and Zn particles. Mg/Zn-embedded PLGA membranes exhibited 166% higher mechanical strength in comparison with pure PLGA membranes and showed suitable degradation properties with a sequential ion release behavior of Mg²⁺ first and continuously Zn²⁺. More importantly, the release of Zn²⁺ from bi-layered PLGA endowed GBR membranes with excellent antibacterial activity (antibacterial rate > 69.3%) as well as good cytocompatibility with MC3T3-E1 (mouse calvaria pre-osteoblastic cells) and HGF-1 (human gingival fibroblast cells). Thus, the asymmetric bi-layered PLGA membranes embedded with Mg and Zn particles provide a simple and effective strategy to not only reinforce the PLGA membrane but also endow membranes with osteogenic and antibacterial activity due to the continuous ion release profile, which serves as a promising candidate for use in GBR therapy.

Plant-Derived Polyphenol and LL-37 Peptide-Modified Nanofibrous Scaffolds for Promotion of Antibacterial Activity, Anti-Inflammation, and Type-H Vascularized Bone Regeneration

The regeneration of oral tissues is a challenging clinical problem because of the complex microbial and biological stress environments. Electrospun fibrous scaffolds have attracted significant interest as effective barrier membranes for guided bone regeneration (GBR); however, no mature strategy yet exists for the surface modification of fibers to provide versatility to satisfy clinical requirements. This study demonstrated a practical biosafety strategy: the combined use of plant polyphenols and LL-37 peptides to modify the fiber surface to endow the fibrous scaffold with antimicrobial activity, immunoregulation, and vascularized bone regeneration. We confirmed that the LL-37 peptides interacted with tannic acid (TA) through noncovalent bonds through experiments and molecular docking simulation analysis. In vitro experiments showed that the TA coating imparted strong antibacterial properties to the fibrous scaffold, but it also caused cytotoxicity. The grafting of LL-37 peptide promoted the spreading, migration, and osteogenic differentiation of mesenchymal stem cells and was also conducive to the M2 polarization of RAW264.7 cells. In vivo experiments further verified that the LL-37 peptide-grafted fibrous scaffold significantly enhanced angiogenesis, anti-inflammatory effects, and type-H vascularized bone regeneration. Overall, the fibrous scaffold modified by the LL-37 peptide through TA grafting has significant potential for GBR applications.

Fabrication of biologically inspired electrospun collagen/silk fibroin/bioactive glass composited nanofibrous to accelerate the treatment efficiency of wound repair

A triple-layer matrix Collagen/Silk fibroin/Bioactive glass composited Nanofibrous was fabricated by linking electrospinning and freeze-drying systems, this typical three layered composite with a nanofibrous fragment as the key (top) layer, middle portion as inferior, and a spongy porous fragment as the third (bottom) deposit to develop the synergistic effect of composite materials resultant to physical and biological performances. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy were used to assess the final material's physicochemical properties (SEM). The triple-layer matrix had a nanofibrous and porous structure, which has qualities including high porosity, swelling, and stability, which are important in soft-tissue engineering. NIH 3 T3 fibroblast and humanoid keratinocyte (HaCaT) cell lines were also used to investigate the matrix's in vitro biological and fluorescent capabilities, which showed excellent cell adherence and proliferation across the composite layers. The synergistic arrangement of nanofibrous substantial deposition onto collagenous with silk fibroin candidates has therefore proven effective in the construction of a tri-layer matrix for skin-tissue-engineering applications.

Valorization of Fish Waste: Isolation and Characterization of Acid- and Pepsin-Soluble Collagen from the Scales of Mediterranean Fish and Fabrication of Collagen-Based Nanofibrous Scaffolds

In search of alternative and sustainable sources of collagenous materials for biomedical applications, the scales of five Mediterranean fish species-fished in high tonnage in the Mediterranean region since they represent popular choices for the local diet-as well as those of the Atlantic salmon for comparison purposes, were comparatively studied for their acid- and pepsin-soluble collagen content. Fish scales that currently represent a discarded biomass of no value could be efficiently exploited for the production of a high added-value biomaterial. The isolated collagenous materials, which showed the typical electrophoretic patterns of type I collagen, were morphologically and physicochemically characterized. Using scanning electron microscopy the fibrous morphology of the isolated collagens was confirmed, while the hydroxyproline content, in conjunction with infrared spectroscopy and X-ray diffraction studies verified the characteristic for collagen amino acid profile and its secondary structure. The acid- and pepsin-soluble collagens isolated from the fish scales were blended with the bioactive sulfated marine polysaccharide ulvan and polyethylene oxide and electrospun to afford nanofibrous scaffolds that could find applications in the biomedical sector.

Viability and Adhesion of Periodontal Ligament Fibroblasts on a Hydroxyapatite Scaffold Combined with Collagen, Polylactic Acid-Polyglycolic Acid Copolymer and Platelet-Rich Fibrin: A Preclinical Pilot Study

Background: Conventional periodontal therapy relies on bone regeneration strategies utilizing scaffolds made of diverse materials, among which collagen, to promote cell adhesion and growth. Objective: To evaluate periodontal ligament fibroblast (HPdLF) cell adhesion and viability for periodontal regeneration purposes on hydroxyapatite scaffolds containing collagen (HAp-egg shell) combined with polylactic acid−polyglycolic acid copolymer (PLGA) and Platelet-Rich Fibrin (PRF). Methods: Four variations of the HAp-egg shell were used to seed HPdLF for 24 h and evaluate cell viability through a live/dead assay: (1) (HAp-egg shell/PLGA), (2) (HAp-egg shell/PLGA + collagen), (3) (HAp-egg shell/PLGA + PRF) and (4) (HAp-egg shell/PLGA + PRF + collagen). Cell adhesion and viability were determined using confocal microscopy and quantified using central tendency and dispersion measurements; significant differences were determined using ANOVA (p < 0.05). Results: Group 1 presented low cell viability and adhesion (3.70−10.17%); groups 2 and 3 presented high cell viability and low cell adhesion (group 2, 59.2−11.1%, group 3, 58−4.6%); group 4 presented the highest cell viability (82.8%) and moderate cell adhesion (45%) (p = 0.474). Conclusions: The effect of collagen on the HAp-egg shell/PLGA scaffold combined with PRF favored HPdLF cell adhesion and viability and could clinically have a positive effect on bone defect resolution and the regeneration of periodontal ligament tissue.

Recent Advances in Designing Fibrous Biomaterials for the Domain of Biomedical, Clinical, and Environmental Applications

Unique properties and potential applications of nanofibers have emerged as innovative approaches and opportunities in the biomedical, healthcare, environmental, and biosensor fields. Electrospinning and centrifugal spinning strategies have gained considerable attention among all kinds of strategies to produce nanofibers. These techniques produce nanofibers with high porosity and surface area, adequate pore architecture, and diverse chemical compositions. The extraordinary characteristics of nanofibers have unveiled new gates in nanomedicine to establish innovative fiber-based formulations for biomedical use, healthcare, and a wide range of other applications. The present review aims to provide a comprehensive overview of nanofibers and their broad range of applications, including drug delivery, biomedical scaffolds, tissue/bone-tissue engineering, dental applications, and environmental remediation in a single place. The review begins with a brief introduction followed by potential applications of nanofibers. Finally, the future perspectives and current challenges of nanofibers are demonstrated. This review will help researchers to engineer more efficient multifunctional nanofibers with improved characteristics for their effective use in broad areas. We strongly believe this review is a reader's delight and will help in dealing with the fundamental principles and applications of nanofiber-based scaffolds. This review will assist students and a broad range of scientific communities to understand the significance of nanofibers in several domains of nanotechnology, nanomedicine, biotechnology, and environmental remediation, which will set a benchmark for further research.

Recent Advances in Hydroxyapatite-Based Biocomposites for Bone Tissue Regeneration in Orthopedics

Bone tissue is a nanocomposite consisting of an organic and inorganic matrix, in which the collagen component and the mineral phase are organized into complex and porous structures. Hydroxyapatite (HA) is the most used ceramic biomaterial since it mimics the mineral composition of the bone in vertebrates. However, this biomimetic material has poor mechanical properties, such as low tensile and compressive strength, which make it not suitable for bone tissue engineering (BTE). For this reason, HA is often used in combination with different polymers and crosslinkers in the form of composites to improve their mechanical properties and the overall performance of the implantable biomaterials developed for orthopedic applications. This review summarizes recent advances in HA-based biocomposites for bone regeneration, addressing the most widely employed inorganic matrices, the natural and synthetic polymers used as reinforcing components, and the crosslinkers added to improve the mechanical properties of the scaffolds. Besides presenting the main physical and chemical methods in tissue engineering applications, this survey shows that HA biocomposites are generally biocompatible, as per most in vitro and in vivo studies involving animal models and that the results of clinical studies on humans sometimes remain controversial. We believe this review will be helpful as introductory information for scientists studying HA materials in the biomedical field.

Polylactide Perspectives in Biomedicine: From Novel Synthesis to the Application Performance

The incessant developments in the pharmaceutical and biomedical fields, particularly, customised solutions for specific diseases with targeted therapeutic treatments, require the design of multicomponent materials with multifunctional capabilities. Biodegradable polymers offer a variety of tailored physicochemical properties minimising health adverse side effects at a low price and weight, which are ideal to design matrices for hybrid materials. PLAs emerge as an ideal candidate to develop novel materials as are endowed withcombined ambivalent performance parameters. The state-of-the-art of use of PLA-based materials aimed at pharmaceutical and biomedical applications is reviewed, with an emphasis on the correlation between the synthesis and the processing conditions that define the nanostructure generated, with the final performance studies typically conducted with either therapeutic agents by in vitro and/or in vivo experiments or biomedical devices.

Photocrosslinkable Col/PCL/Mg composite membrane providing spatiotemporal maintenance and positive osteogenetic effects during guided bone regeneration

Guided bone regeneration membranes have been effectively applied in oral implantology to repair bone defects. However, typical resorbable membranes composed of collagen (Col) have insufficient mechanical properties and high degradation rate, while non-resorbable membranes need secondary surgery. Herein, we designed a photocrosslinkable collagen/polycaprolactone methacryloyl/magnesium (Col/PCLMA/Mg) composite membrane that provided spatiotemporal support effect after photocrosslinking. Magnesium particles were added to the PCLMA solution and Col/PCLMA and Col/PCLMA/Mg membranes were developed; Col membranes and PCL membranes were used as controls. After photocrosslinking, an interpenetrating polymer network was observed by scanning electron microscopy (SEM) in Col/PCL and Col/PCL/Mg membranes. The elastic modulus, swelling behavior, cytotoxicity, cell attachment, and cell proliferation of the membranes were evaluated. Degradation behavior in vivo and in vitro was monitored according to mass change and by SEM. The membranes were implanted into calvarial bone defects of rats for 8 weeks. The Col/PCL and Col/PCL/Mg membranes displayed much higher elastic modulus (p < 0.05), and a lower swelling rate (p < 0.05), than Col membranes, and there were no differences in cell biocompatibility among groups (p > 0.05). The Col/PCL and Col/PCL/Mg membranes had lower degradation rates than the Col membranes, both in vivo and in vitro (p < 0.05). The Col/PCL/Mg groups showed enhanced osteogenic capability compared with the Col groups at week 8 (p < 0.05). The Col/PCL/Mg composite membrane represents a new strategy to display space maintenance and enhance osteogenic potential, which meets clinical needs.

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Photocrosslinked Col/PCL and Col/PCL/Mg membranes displayed good mechanical support to provide space for bone regeneration.

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Col/PCL and Col/PCL/Mg membranes had suitable degradation rates for the maintenance duration of bone regeneration.

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Photocrosslinked Col/PCL/Mg membranes enhanced osteogenesis and expedited the formation of high-quality bone on week 8.

Preparation and Characterization of Tilapia Collagen-Thermoplastic Polyurethane Composite Nanofiber Membranes

Marine collagen is an ideal material for tissue engineering due to its excellent biological properties. However, the limited mechanical properties and poor stability of marine collagen limit its application in tissue engineering. Here, collagen was extracted from the skin of tilapia (Oreochromis nilotica). Collagen-thermoplastic polyurethane (Col-TPU) fibrous membranes were prepared using tilapia collagen as a foundational material, and their physicochemical and biocompatibility were investigated. Fourier transform infrared spectroscopy results showed that thermoplastic polyurethane was successfully combined with collagen, and the triple helix structure of collagen was retained. X-ray diffraction and differential scanning calorimetry results showed relatively good compatibility between collagen and TPU.SEM results showed that the average diameter of the composite nanofiber membrane decreased with increasing thermoplastic polyurethane proportion. The mechanical evaluation and thermogravimetric analysis showed that the thermal stability and tensile properties of Col-TPU fibrous membranes were significantly improved with increasing TPU. Cytotoxicity experiments confirmed that fibrous membranes with different ratios of thermoplastic polyurethane content showed no significant toxicity to fibroblasts; Col-TPU fibrous membranes were conducive to the migration and adhesion of cells. Thus, these Col-TPU composite nanofiber membranes might be used as a potential biomaterial in tissue regeneration.

Collagen Membrane Derived from Fish Scales for Application in Bone Tissue Engineering

Guided tissue/bone regeneration (GTR/GBR) is currently the main treatment for alveolar bone regeneration. The commonly used barrier membranes in GTR/GBR are collagen membranes from mammals such as porcine or cattle. Fish collagen is being explored as a potential substitute for mammalian collagen due to its low cost, no zoonotic risk, and lack of religious constraints. Fish scale is a multi-layer natural collagen composite with high mechanical strength, but its biomedical application is limited due to the low denaturation temperature of fish collagen. In this study, a fish scale collagen membrane with a high denaturation temperature of 79.5 °C was prepared using an improved method based on preserving the basic shape of fish scales. The fish scale collagen membrane was mainly composed of type I collagen and hydroxyapatite, in which the weight ratios of water, organic matter, and inorganic matter were 20.7%, 56.9%, and 22.4%, respectively. Compared to the Bio-Gide^® membrane (BG) commonly used in the GTR/GBR, fish scale collagen membrane showed good cytocompatibility and could promote late osteogenic differentiation of cells. In conclusion, the collagen membrane prepared from fish scales had good thermal stability, cytocompatibility, and osteogenic activity, which showed potential for bone tissue engineering applications.

The Effect of Ca2+ and Mg2+ Ions Loaded at Degradable PLA Membranes on the Proliferation and Osteoinduction of MSCs

Biodegradable membranes, including Polylactic acid (PLA)-based membranes, are commonly used in bone-tissue-related clinical procedures as biointerface to promote bone tissue regeneration. Calcium (Ca²⁺) and Magnesium (Mg²⁺) ions have been related to the promotion of osteogenesis, where the PLA membranes could be used as carrier and delivery substrate for them to provide osteogenic properties to this material. For this aim, a new ion delivery system based on biodegradable PLA membranes loaded with Mg and hydroxyapatite (HA) particles has been processed by the combination of tape casting and colloidal route. Materials characterization shows that the incorporation of Mg and HA particles changes the surface and hydrophobicity of the PLA membrane, and the in vitro degradation test shows Mg²⁺ and Ca²⁺ ion release and occasionally the precipitation of different ion species onto the membrane surface. Mouse and human Mesenchymal Stem Cells (MSC) were used to define the biocompatibility and bioactivity of these PLA membrane composites, and data indicated Mg²⁺ promotes cell proliferation and potentiates osteoinductive signals, while Ca²⁺ induces the expression of ALP osteogenic marker in human MSCs. Biodegradable PLA membranes loaded with Mg and HA particles is a promising new ion delivery system of Mg²⁺ and Ca²⁺ ions that provides osteogenic signals and works as functional biointerface interfaces with bone tissues.

Marine Biopolymers as Bioactive Functional Ingredients of Electrospun Nanofibrous Scaffolds for Biomedical Applications

Marine biopolymers, abundantly present in seaweeds and marine animals, feature diverse structures and functionalities, and possess a wide range of beneficial biological activities. Characterized by high biocompatibility and biodegradability, as well as unique physicochemical properties, marine biopolymers are attracting a constantly increasing interest for the development of advanced systems for applications in the biomedical field. The development of electrospinning offers an innovative technological platform for the production of nonwoven nanofibrous scaffolds with increased surface area, high encapsulation efficacy, intrinsic interconnectivity, and structural analogy to the natural extracellular matrix. Marine biopolymer-based electrospun nanofibrous scaffolds with multifunctional characteristics and tunable mechanical properties now attract significant attention for biomedical applications, such as tissue engineering, drug delivery, and wound healing. The present review, covering the literature up to the end of 2021, highlights the advancements in the development of marine biopolymer-based electrospun nanofibers for their utilization as cell proliferation scaffolds, bioadhesives, release modifiers, and wound dressings.

Natural polyphenol-based nanoengineering of collagen-constructed hemoperfusion adsorbent for the excretion of heavy metals

Designing a hemoperfusion adsorbent for the excretion therapy of toxic heavy metals still remains a great challenge due to the biosafety risks of non-biological materials and the desired highly efficient removal capacity. Herein, inspired from the homeostasis mechanism of plants, natural polyphenols are integrated with collagen matrix to construct a polyphenol-functionalized collagen-based artificial liver (PAL) for heavy metals excretion and free radicals scavenging therapy. PAL presents high adsorption capacities for Cu²⁺, Pb²⁺, and UO₂²⁺ ions, up to 76.98 μmol g^-1, 106.70 μmol g^-1, and 252.48 μmol g^-1, respectively. Remarkably, PAL possesses a high binding affinity for UO₂²⁺, Pb²⁺, and Cu²⁺ ions even in the complex serum environment with the presence of biologically-relevant ions (e.g., Mg²⁺, Ca²⁺ ions). Low hemolysis ratio (1.77%), high cell viability (> 85%), high plasma recalcification time (17.4 min), and low protein adsorption (1.02 μmol g^-1) indicate outstanding biocompatibility of this material. This natural polyphenol/collagen-based fully bio-derived hemoperfusion adsorbent provides a novel and potentially applicable strategy for constructing a hemoperfusion adsorbent for heavy metal ions excretion therapy with efficiency and biosafety.

Influence of Fish Scale-Based Hydroxyapatite on Forcespun Polycaprolactone Fiber Scaffolds

Marine waste byproducts, especially fish scales, have proved to be one of the most prominent sources for developing sustainable materials for various applications including biomedical applications. Hydroxyapatite (HAp), being one of such biomaterials that can be synthesized from the massive fish-based waste, has received plentitude of attention due to its excellent ability to promote cell growth and proliferation. However, understanding the influence of HAp on polymer matrices that are tailored for biomedical applications is still a challenge. This study is intended to develop a sophisticated yet inexpensive method to obtain nonwoven polycaprolactone (PCL) nanofibrous scaffolds and analyze the influence of calcium-deficient nanoporous hydroxyapatite (n-HAp) on the thermal, mechanical, and biological properties of these scaffolds. The n-HAp is synthesized using two different types of fish scales, carpa (CA) and pink perch (PP), by calcination followed by nanomilling. The synthesized n-HAp powder is characterized by using X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy. The PCL fibrous scaffolds were developed using a novel forcespinning technique with n-HAp as the filler. The morphology of the scaffolds was characterized using SEM and Raman spectroscopy. SEM and TEM results have confirmed the size reduction of the HAp powder after nanomilling. Thermal properties were analyzed using thermogravimetric analysis and differential scanning calorimetry. The major degradation temperature has increased by 3° and was observed to be 398° for 1 wt % filler loading for both carpa and pink perch-derived n-HAp. The increase in filler content has increased the residue left after decomposition and is 4% for 5 wt % filler loading. The crystallinity percent has increased by 7% compared to neat fibers for 1 wt % filler loading. Mechanical properties were tested using tensile tests. The tensile test strength has shown 32% improvement for 1 wt % compared to neat fibers. Cell viability tests were performed using hFOB cells which have shown significant cell growth for a high filler loading of 5 wt %. The results suggest that both CA-n-HAP and PP-n-Hap-incorporated fibrous scaffolds can be used potentially for biomedical applications after careful investigation of the scaffold behavior with longer incubation periods.

Advances in Modification Methods Based on Biodegradable Membranes in Guided Bone/Tissue Regeneration: A Review

Guided tissue/bone regeneration (GTR/GBR) is commonly applied in dentistry to aid in the regeneration of bone/tissue at a defective location, where the assistive material eventually degrades to be substituted with newly produced tissue. Membranes separate the rapidly propagating soft tissue from the slow-growing bone tissue for optimal tissue regeneration results. A broad membrane exposure area, biocompatibility, hardness, ductility, cell occlusion, membrane void ratio, tissue integration, and clinical manageability are essential functional properties of a GTR/GBR membrane, although no single modern membrane conforms to all of the necessary characteristics. This review considers ongoing bone/tissue regeneration engineering research and the GTR/GBR materials described in this review fulfill all of the basic ISO requirements for human use, as determined through risk analysis and rigorous testing. Novel modified materials are in the early stages of development and could be classified as synthetic polymer membranes, biological extraction synthetic polymer membranes, or metal membranes. Cell attachment, proliferation, and subsequent tissue development are influenced by the physical features of GTR/GBR membrane materials, including pore size, porosity, and mechanical strength. According to the latest advances, key attributes of nanofillers introduced into a polymer matrix include suitable surface area, better mechanical capacity, and stability, which enhances cell adhesion, proliferation, and differentiation. Therefore, it is essential to construct a bionic membrane that satisfies the requirements for the mechanical barrier, the degradation rate, osteogenesis, and clinical operability.

Engineering Electrospun Nanofibers for the Treatment of Oral Diseases

With the increase of consumption of high-sugar foods, beverages, tobacco, and alcohol, the incidence rate of oral diseases has been increasing year by year. Statistics showed that the prevalence of oral diseases such as dental caries, dental pulpal disease, and periodontal disease has reached as high as 97% in 2015 in China. It is thus urgent to develop functional materials or products for the treatment of oral diseases. Electrospinning has been a widely used technology that is capable of utilizing polymer solution to generate micro/nano fibers under an appropriate high voltage condition. Owing to their excellent structures and biological performances, materials prepared by electrospinning technology have been used for a wide range of oral-related applications, such as tissue restoration, controlled drug release, anti-cancer, etc. In this regard, this article reviews the application and progress of electrospun nanofibers to various oral diseases in recent years. Firstly, engineering strategies of a variety of nanofiber structures together with their resultant functions will be introduced. Then, biological functions of electrospun nanofibers as well as their applications in the treatment of oral diseases are summarized and demonstrated. Finally, the development viewpoint of functional nanofibers is prospected, which is expected to lay the foundation and propose the direction for further clinical application.

The diameter factor of aligned membranes facilitates wound healing by promoting epithelialization in an immune way

Topographical properties, such as pattern and diameter, of biomaterials play important roles in influencing cell activities and manipulating the related immune response during wound healing. We prepared aligned electrospinning membranes with different fiber diameters, including 319 ± 100 nm (A300), 588 ± 132 nm (A600), and 1048 ± 130 nm (A1000), by adjusting the distance from the tip to the collector, the injection rate, and the concentration of the solution. The A300 membranes significantly improved cell proliferation and spreading and facilitated wound healing (epithelization and vascularization) with the regeneration of immature hair follicles compared to the other membranes. Transcriptomics revealed the underlying molecular mechanism that A300 could promote immune-related processes towards a pro-healing direction, significantly promoting keratinocyte migration and skin wound healing. All the results indicated that wound healing requires the active participation of the immune process, and that A300 was a potential candidate for guided skin regeneration applications.

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It is still unclear which diameter interval of aligned membranes is most suitable for tissue regeneration.

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Outstanding performances in the wound healing process was presented by the A300 membranes.

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The transcriptome revealed that A300 could promote immune related processes towards a pro-healing direction.

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A300 promoted keratinocytes migration and final wound healing partially through MMP12.

Marine collagen scaffolds in tissue engineering

Collagen is the primary component of the extracellular matrix in humans. Traditionally commercial collagen is confined to bovine and porcine sources which have concerns of pathogenic transfer. Marine wastage accounts up to 85% by weight in the fishing industry. Extraction of collagen from these wastes for economic value and environmental sustainability is clear. Marine collagens have several advantages such as excellent biocompatibility, lower zoonotic risks, less immunological risk for patients allergic to mammalian products, and less religious restrictions. However, the properties of marine collagen-based constructs are highly dependent on the methods of fabrication. This article reviews advances in the design and fabrication of marine collagen-based constructs for medical applications. The potential applications of marine collagen in the regeneration of skin, bone and cartilage were also highlighted.

Collagen-based biocomposites inspired by bone hierarchical structures for advanced bone regeneration: ongoing research and perspectives

Bone is a hard-connective tissue composed of matrix, cells and bioactive factors with a hierarchical structure, where the matrix is mainly composed of type I collagen and hydroxyapatite. Collagen fibers assembled by collagen are the template for mineralization and make an important contribution to bone formation and the bone remodeling process. Therefore, collagen has been widely clinically used for bone/cartilage defect regeneration. However, pure collagen implants, such as collagen scaffolds or sponges, have limitations in the bone/cartilage regeneration process due to their poor mechanical properties and osteoinductivity. Different forms of collagen-based composites prepared by incorporating natural/artificial polymers or bioactive inorganic substances are characterized by their interconnected porous structure and promoting cell adhesion, while they improve the mechanical strength, structural stability and osteogenic activities of the collagen matrix. In this review, various forms of collagen-based biocomposites, such as scaffolds, sponges, microspheres/nanoparticles, films and microfibers/nanofibers prepared by natural/synthetic polymers, bioactive ceramics and carbon-based materials compounded with collagen are reviewed. In addition, the application of collagen-based biocomposites as cytokine, cell or drug (genes, proteins, peptides and chemosynthetic) delivery platforms for proangiogenesis and bone/cartilage tissue regeneration is also discussed. Finally, the potential application, research and development direction of collagen-based biocomposites in future bone/cartilage tissue regeneration are discussed.

A baicalin-loaded coaxial nanofiber scaffold regulated inflammation and osteoclast differentiation for vascularized bone regeneration

We demonstrate a simple, effective and feasible method to address the shrinkage of Poly (lactic-co-glycolic acid) (PLGA) through a core-shell structure fiber strategy. The results revealed that introducing size-stable poly-caprolactone (PCL) as the core fiber significantly improved the PLGA-based fibrous scaffold's dimensional maintenance. We further utilized fish collagen to modify the PLGA shell layer (PFC) of coaxial fibers and loaded baicalin (BA) into the PCL core layer (PCL-BA) to endow fibrous scaffold with more functional biological cues. The PFC/PCL-BA fibrous scaffold promoted the osteogenic differentiation of bone mesenchymal stem cells and stimulated the RAW264.7 cells to polarize into a pro-reparative phenotype. Importantly, the in vivo study demonstrated that the PFC/PCL-BA scaffold could regulate inflammation and osteoclast differentiation, favor neovascularization and bone formation. This work tactfully combined PLGA and PCL to establish a drug release platform based on the core-shell fibrous scaffold for vascularized bone regeneration.

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A multifunctional baicalin-loaded coaxial fiber scaffold prepared by electrospinning.

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The coaxial nanofiber can effectively resist the shrinkage of PLGA.

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Baicalin endow the nanofibrous scaffold with excellent biological properties.

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The scaffold can alleviate the inflammation and achieve vascularized bone regeneration.

Marine-Derived Collagen as Biomaterials for Human Health

Collagen is a kind of biocompatible protein material, which is widely used in medical tissue engineering, drug delivery, cosmetics, food and other fields. Because of its wide source, low extraction cost and good physical and chemical properties, it has attracted the attention of many researchers in recent years. However, the application of collagen derived from terrestrial organisms is limited due to the existence of diseases, religious beliefs and other problems. Therefore, exploring a wider range of sources of collagen has become one of the main topics for researchers. Marine-derived collagen (MDC) stands out because it comes from a variety of sources and avoids issues such as religion. On the one hand, this paper summarized the sources, extraction methods and characteristics of MDC, and on the other hand, it summarized the application of MDC in the above fields. And on the basis of the review, we found that MDC can not only be extracted from marine organisms, but also from the wastes of some marine organisms, such as fish scales. This makes further use of seafood resources and increases the application prospect of MDC.

Topological structure of electrospun membrane regulates immune response, angiogenesis and bone regeneration

The fate of biomaterials is orchestrated by biocompatibility and bioregulation characteristics, reported to be closely related to topographical structures. For the purpose to investigate the topography of fibrous membranes on the guided bone regeneration performance, we successfully fabricated poly (lactate-co-glycolate)/fish collagen/nano-hydroxyapatite (PFCH) fibrous membranes with random, aligned and latticed topography by electrospinning. The physical, chemical and biological properties of the three topographical PFCH membranes were systematically investigated by in vitro and in vivo experiments. The subcutaneous implantation of C57BL6 mice showed an acceptable mild foreign body reaction of all three topological membranes. Interestingly, the latticed PFCH membrane exhibited superior abilities to recruit macrophage/monocyte and induce angiogenesis. We further investigated the osteogenesis of the three topographical PFCH membranes via the critical-size calvarial bone defect model of rats and mice and the results suggested that latticed PFCH membrane manifested promising performance to promote angiogenesis through upregulation of the HIF-1α signaling pathway; thereby enhancing bone regeneration. Our research illustrated that the topological structure of fibrous membranes, as one of the characteristics of biomaterials, could regulate its biological functions, and the fibrous structure of latticed topography could serve as a favorable surface design of biomaterials for bone regeneration. STATEMENT OF SIGNIFICANCE: In material-mediated regeneration medicine, the interaction between the biomaterial and the host is key to successful tissue regeneration. The micro-and nano-structure becomes one of the most critical physical clues for designing biomaterials. In this study, we fabricated three topological electrospun membranes (Random, Aligned and Latticed) to understand how topological structural clues mediate bone tissue regeneration. Interestingly, we found that the Latticed topographical PFCH membrane promotes macrophage recruitment, angiogenesis, and osteogenesis in vivo, indicating the fibrous structure of latticed topography could serve as a favorable surface design of biomaterials for bone regeneration.

Application of marine collagen for stem-cell-based therapy and tissue regeneration (Review)

Tissue engineering and regenerative medicine is becoming an important component in modern biological scientific research. Tissue engineering, a branch of regenerative medicine, is a field that is actively developing to meet the challenges presented in biomedical applications. This particularly applies to the research area of stem cells and biomaterials, due to both being pivotal determinants for the successful restoration or regeneration of damaged tissues and organs. Recently, the development of innovative marine collagen-based biomaterials has attracted attention due to the reported environmentally friendly properties, the lack of zoonotic disease transmission, biocompatibility, bioactivity, the lack of ethics-related concerns and cost-effectiveness for manufacturing. The present review aimed to summarize the potential application and function of marine collagen in stem cell research in a medical and clinical setting. In addition, the present review cited recent studies regarding the latest research advances into using marine collagen for cartilage, bone, periodontal and corneal regeneration. It also characterized the distinct advantages of using marine collagen for stem cell-based tissue repair and regeneration. In addition, the present review comprehensively discussed the most up to date information on stem cell biology, particularly the possibility of treating stem cells with marine collagen to maximize their multi-directional differentiation capability, which highlights the potential use of marine collagen in regenerative medicine. Furthermore, recent research progress on the potential immunomodulatory capacity of mesenchymal stem cells following treatment with marine collagen to improve the understanding of cell-matrix interactions was investigated. Finally, perspectives on the possible future research directions for the application of marine collagen in the area of regenerative medicine are provided.

Physical and biological performances of a semi-resorbable barrier membrane based on silk fibroin-glycerol-fish collagen material for guided bone regeneration

The fragility of silk fibroin film is a drawback to being used as a barrier membrane. Semi-resorbable barrier membranes maintain function longer than a resorbable membrane and no need to be removed. The study aimed to fabricate semi-resorbable membranes using silk fibroin with glycerol plasticizer (Group A), immobilized with fish collagen (Group B), and then characterized, in vitro biocompatibility tested, and compared with a commercial collagen membrane (Group C). Group B showed more roughness (0.2155 µm) than Group A (0.1424 µm). Group A was more hydrophilic (76.75° ± 3.07°) and more stiffness (28.93% ± 15.56%) than Group B (112.67° ± 1.94°, 42.10% ± 11.46%) and C (54.79% ± 13.44%) without significant difference. Group C had a significantly higher (p < 0.05) swelling degree and less degradation rate than others. Group A showed significantly highest (p < 0.05) cell proliferation. Group C showed more alkaline phosphatase activity than others but no significant difference in osteocalcin and Alizarin Red activity on day 21. The semi-resorbable membrane based on silk fibroin-glycerol possessed good physical and mechanical properties, and well-supported osteoblastic cell proliferation and differentiation.

Recent advances in PLGA-based biomaterials for bone tissue regeneration

Bone regeneration is an interdisciplinary complex lesson, including but not limited to materials science, biomechanics, immunology, and biology. Having witnessed impressive progress in the past decades in the development of bone substitutes; however, it must be said that the most suitable biomaterial for bone regeneration remains an area of intense debate. Since its discovery, poly (lactic-co-glycolic acid) (PLGA) has been widely used in bone tissue engineering due to its good biocompatibility and adjustable biodegradability. This review systematically covers the past and the most recent advances in developing PLGA-based bone regeneration materials. Taking the different application forms of PLGA-based materials as the starting point, we describe each form's specific application and its corresponding advantages and disadvantages with many examples. We focus on the progress of electrospun nanofibrous scaffolds, three-dimensional (3D) printed scaffolds, microspheres/nanoparticles, hydrogels, multiphasic scaffolds, and stents prepared by other traditional and emerging methods. Finally, we briefly discuss the current limitations and future directions of PLGA-based bone repair materials. STATEMENT OF SIGNIFICANCE: As a key synthetic biopolymer in bone tissue engineering application, the progress of PLGA-based bone substitute is impressive. In this review, we summarized the past and the most recent advances in the development of PLGA-based bone regeneration materials. According to the typical application forms and corresponding crafts of PLGA-based substitutes, we described the development of electrospinning nanofibrous scaffolds, 3D printed scaffolds, microspheres/nanoparticles, hydrogels, multiphasic scaffolds and scaffolds fabricated by other manufacturing process. Finally, we briefly discussed the current limitations and proposed the newly strategy for the design and fabrication of PLGA-based bone materials or devices.

Bioinspired mineralized collagen scaffolds for bone tissue engineering

Successful regeneration of large segmental bone defects remains a major challenge in clinical orthopedics, thus it is of important significance to fabricate a suitable alternative material to stimulate bone regeneration. Due to their excellent biocompatibility, sufficient mechanical strength, and similar structure and composition of natural bone, the mineralized collagen scaffolds (MCSs) have been increasingly used as bone substitutes via tissue engineering approaches. Herein, we thoroughly summarize the state of the art of MCSs as tissue-engineered scaffolds for acceleration of bone repair, including their fabrication methods, critical factors for osteogenesis regulation, current opportunities and challenges in the future. First, the current fabrication methods for MCSs, mainly including direct mineral composite, in-situ mineralization and 3D printing techniques, have been proposed to improve their biomimetic physical structures in this review. Meanwhile, three aspects of physical (mechanics and morphology), biological (cells and growth factors) and chemical (composition and cross-linking) cues are described as the critical factors for regulating the osteogenic feature of MCSs. Finally, the opportunities and challenges associated with MCSs as bone tissue-engineered scaffolds are also discussed to point out the future directions for building the next generation of MCSs that should be endowed with satisfactorily mimetic structures and appropriately biological characters for bone regeneration.

Sustainable aquaculture side-streams derived hybrid biocomposite for bone tissue engineering

Despite being a rich source of bioactive compounds, the current exploitation of aquatic biomass is insufficient. Majority of the aquaculture industry side-streams are currently used for low-value purposes such as animal feed or composting material, with low economical returns. To maximize resource reuse and minimize waste generation, valorization efforts should be augmented with the aim to produce high-value products. Herein, we present a novel aquaculture wastes-derived multi-scale osteoconductive hybrid biocomposite that is composed of chemically crosslinked American bullfrog (Rana catesbeiana) skin-derived type I tropocollagen nanofibrils (~22.3 nm) network and functionalized with micronized (~1.6 μm) single-phase hydroxyapatite (HA) from discarded snakehead (Channa micropeltes) fish scales. The bioengineered construct is biocompatible, highly porous (>90%), and exhibits excellent osteoconductive properties, as indicated by robust adhesion and proliferation of human fetal osteoblastic 1.19 cell line (hFOB 1.19). Furthermore, increased expression level of osteo-related ALPL and BGLAP mRNA transcripts, as well as enhanced osteocalcin immunoreactivity and increasing Alizarin red S staining coverage on the hybrid biocomposite was observed over 21 days of culture. Collectively, the devised "waste-to-resource" platform represents a sustainable waste valorization strategy that is amendable for advanced bone repair and regeneration applications.

Diverse and Productive Source of Biopolymer Inspiration: Marine Collagens

Marine biodiversity is expressed through the huge variety of vertebrate and invertebrate species inhabiting intertidal to deep-sea environments. The extraordinary variety of "forms and functions" exhibited by marine animals suggests they are a promising source of bioactive molecules and provides potential inspiration for different biomimetic approaches. This diversity is familiar to biologists and has led to intensive investigation of metabolites, polysaccharides, and other compounds. However, marine collagens are less well-known. This review will provide detailed insight into the diversity of collagens present in marine species in terms of their genetics, structure, properties, and physiology. In the last part of the review the focus will be on the most common marine collagen sources and on the latest advances in the development of innovative materials exploiting, or inspired by, marine collagens.

Applications of marine collagens in bone tissue engineering

For decades, collagen has been among the most widely used biomaterials with several biomedical applications. Recently, researchers have shown a keen interest in collagen obtained from marine sources because of its biocompatibility, biodegradability, ease of extractability, safety, low immunogenicity, and low production costs. A wide variety of marine collagen-based scaffolds have been developed for bone tissue engineering, and these scaffolds display excellent biological effects. This review aims to provide an overview of the biological effects of marine collagen in bone engineering, such as promoting osteogenesis and collagen synthesis, inhibiting inflammation, inducing the differentiation of cartilage, and improving bone mineral density. Marine collagen holds great promise as a biomaterial in bone tissue engineering.

An overview of polyester/hydroxyapatite composites for bone tissue repairing

Objectives

The polyester/hydroxyapatite (polyester/HA) composites play an important role in bone tissue repairing, mostly because they mimic the composition and structure of naturally mineralized bone tissue. This review aimed to discuss commonly used geometries of polyester/HA composites, including microspheres, membranes, scaffolds and bulks, and their applications in bone tissue repairing and to discuss existed restrictions and developing trends of polyester/HA.

Methods

The current review was conducted by searching Web of Science, and Google Scholar for relevant studies published related with polyester/HA composites. Selected studies were analyzed with a focus on the fabrication techniques, properties (mechanical properties, biodegradable properties and biological properties) and applications of polyester/HA composites in bone repairing.

Results

A total of 111 articles were introduced to discuss the review. Different geometries of polyester/HA composites were discussed. In addition, properties and applications of polyester/HA composites were evaluated. The addition of HA into polyester can adjust the mechanical and biodegradability of composites. Besides, the addition of HA into polyester can improve its osteogenic abilities. The results showed that polyester/HA composites can ideal candidate for bone tissue repairing.

Conclusion

Polyester/HA composites have many remarkable properties, such as appropriate mechanical strength, biodegradability, favorable biological properties. Diverse geometries of polyester/HA composites have been used in bone repairing, drug delivery and implant fixation. Further work needs to be done to investigate existed restrictions, including the controlled degradation rate, controlled drug release performance, well-matched mechanical properties, and novel fabrication techniques.

The translational potential of this article

The present review reveals the current state of the polyester/HA composites used in bone tissue repairing, contributing to future trends of polyester/HA composites in the forthcoming future.

The shrinking behavior, mechanism and anti-shrinkage resolution of an electrospun PLGA membrane

The deformation shrinkage of a poly(lactide-co-glycolide) (PLGA) fibrous material seriously affects its biomedical application. To demonstrate the underlying shrinking mechanism and to find a method to prevent the shrinkage of an electrospun PLGA membrane, we investigated the shrinking behavior of PLGA electrospun membranes under various test conditions and discussed the underlying shrinking mechanism. The results indicated that the shrinkage of the electrospun PLGA membrane was mainly regulated by the glass transition of its polymer fiber; the temperature and liquid environment were found to be the two main factors leading to the shrinkage of the electrospun PLGA membrane through affecting its glass transition. Then a heat stretching (HS) technique was proposed by us to stabilize the electrospun PLGA membrane. After HS treatment, the glass transition temperature (Tg) of the electrospun PLGA membrane could increase from 48.38 °C to 54.55 °C. Our results indicated that the HS-treated membranes could maintain a high area percentage of 90.89 ± 2.27% and 84.78 ± 3.36% after immersion respectively in PBS and blood at 37 °C for 2 hours. Further experiments confirmed that the HS technique could also stabilize the dimensional structure of the electrospun PDLLA membrane in PBS and blood at 37 °C. This study provides an effective strategy for preventing the shrinkage of electrospun polyester biomaterials in a physiological environment that may benefit both the material structural stability and the in vivo biological performance.

Bioinspired superwetting fibrous skin with hierarchical roughness for efficient oily water separation

Developing superwetting membranes with interconnected pore and multi-scale roughness for efficient oily water separation is significant but challenging owing to the limitations of low water flux and membrane fouling. Herein, we report a scalable method to develop superwetting membranes with superhydrophilicity and underwater superoleophobicity for oily water separation. This novel approach, composed of electrospinning/electrospraying of polyacrylonitrile (PAN), was to fabricate rough sphere membrane substrate, followed by in-situ polymerization of dopamine/polyethyleneimine (DA/PEI) to positively charge the fiber skin and then subsequent immersed into the negatively charged Ludox solution to construct rough membrane surface via electrostatic attraction. Benefiting from the rough sphere surface of the fibrous skin layer, the resultant membrane displayed micro/nanostructured surfaces with intriguing in-air superhydrophilicity of 0° and underwater superoleophobicity of 166° as well as robust oil-proof pressure of 83.55 kPa. As a proof-of-concept, the resultant membrane achieved high water flux and oil rejection efficiency as well as fantastic durability and antifouling performance toward the separation of highly emulsified oily water. The integration of electrospinning/electrospraying with bioinspired method is also expected to fabricate superwetting sphere surface membrane with interconnected pores for other selective separation applications.

Development of FGF-2-loaded electrospun waterborne polyurethane fibrous membranes for bone regeneration

Guided bone regeneration (GBR) membrane has been used to improve functional outcomes for periodontal regeneration. However, few studies have focused on the biomimetic membrane mimicking the vascularization of the periodontal membrane. This study aimed to fabricate waterborne polyurethane (WPU) fibrous membranes loaded fibroblast growth factor-2 (FGF-2) via emulsion electrospinning, which can promote regeneration of periodontal tissue via the vascularization of the biomimetic GBR membrane. A biodegradable WPU was synthesized by using lysine and dimethylpropionic acid as chain extenders according to the rule of green chemical synthesis technology. The WPU fibers with FGF-2 was fabricated via emulsion electrospinning. The results confirmed that controlled properties of the fibrous membrane had been achieved with controlled degradation, suitable mechanical properties and sustained release of the factor. The immunohistochemical expression of angiogenic-related factors was positive, meaning that FGF-2 loaded in fibers can significantly promote cell vascularization. The fiber scaffold loaded FGF-2 has the potential to be used as a functional GBR membrane to promote the formation of extraosseous blood vessels during periodontal repairing.

Fish Collagen: Extraction, Characterization, and Applications for Biomaterials Engineering

The utilization of marine-based collagen is growing fast due to its unique properties in comparison with mammalian-based collagen such as no risk of transmitting diseases, a lack of religious constraints, a cost-effective process, low molecular weight, biocompatibility, and its easy absorption by the human body. This article presents an overview of the recent studies from 2014 to 2020 conducted on collagen extraction from marine-based materials, in particular fish by-products. The fish collagen structure, extraction methods, characterization, and biomedical applications are presented. More specifically, acetic acid and deep eutectic solvent (DES) extraction methods for marine collagen isolation are described and compared. In addition, the effect of the extraction parameters (temperature, acid concentration, extraction time, solid-to-liquid ratio) on the yield of collagen is investigated. Moreover, biomaterials engineering and therapeutic applications of marine collagen have been summarized.

The long-term behaviors and differences in bone reconstruction of three polymer-based scaffolds with different degradability

Scaffolds composed of polymers and nano-hydroxyapatite (n-HA) have received extensive attention in bone reconstructive repair; however there is a lack of in-depth and long-term comparative study on the effect of scaffold degradability on bone reconstruction. In this study, the osteogenic behaviors of three polymeric composite scaffolds based on fast degradable poly(lactic-co-glycolic acid) (PLGA), slowly degradable polycaprolactone (PCL) and non-degradable polyamide 66 (PA66) were investigated and compared via implanting the scaffolds into rabbit femoral defects for 1, 3, 6 and 12 months. The in vivo results demonstrated that although the n-HA/PLGA scaffold could obtain higher new bone volume at 3 months, its fast degradation caused the loss of scaffold structural integrity and led to reduction of bone volume after 3 months. The n-HA/PCL scaffold displayed slow degradation mainly after 6 months (∼20% degradation) and the n-HA/PA66 scaffold showed no degradation during the entire 12 months; these two scaffolds could maintain their structural integrity and exhibited a constant increase in bone volume with the implantation time, and even achieved higher bone volume than the n-HA/PLGA scaffold at 12 months. The year-long in vivo research revealed the following important aspects: (1) bone reconstruction is strongly related to scaffold degradability, and the scaffold structural integrity should be maintained at least for one year before complete degradation in vivo; (2) the in vivo experiment of a bone scaffold must take more time than the conventional 3 or 6 months, which is normally neglected. The study suggests a principle for future design and application of bone scaffolds that must have a relatively stable osteogenic space and scaffold interface, or have a scaffold degradation speed slower than the time of bone reconstruction completion.