Plant-Derived Nanocellulose as Structural and Mechanical Reinforcement of Freeze-Cast Chitosan Scaffolds for Biomedical Applications

Photopolymerization Approach to Advanced Polymer Composites: Integration of Surface-Modified Nanofillers for Enhanced Properties

The incorporation of functionalized nanofillers into polymers via photopolymerization approach has gained significant attention in recent years due to the unique properties of the resulting composite materials. Surface modification of nanofillers plays a crucial role in their compatibility and polymerization behavior within the polymer matrix during photopolymerization. This review focuses on the recent developments in surface modification of various nanofillers, enabling their integration into polymer systems through photopolymerization. The review discusses the key aspects of surface modification of nanofillers, including the selection of suitable surface modifiers, such as photoinitiators and polymerizable groups, as well as the optimization of modification conditions to achieve desired surface properties. The influence of surface modification on the interfacial interactions between nanofillers and the polymer matrix is also explored, as it directly impacts the final properties of the nanocomposites. Furthermore, the review highlights the applications of nanocomposites prepared by photopolymerization, such as sensors, gas separation membranes, purification systems, optical devices, and biomedical materials. By providing a comprehensive overview of the surface modification strategies and their impact on the photopolymerization process and the resulting nanocomposite properties, this review aims to inspire new research directions and innovative ideas in the development of high-performance polymer nanocomposites for diverse applications.

Anisotropic materials based on carbohydrate polymers: A review of fabrication strategies, properties, and applications

Anisotropic structures exist in almost all living organisms to endow them with superior properties and physiological functionalities. However, conventional artificial materials possess unordered isotropic structures, resulting in limited functions and applications. The development of anisotropic structures on carbohydrates is reported to have an impact on their properties and applications. In this review, various alignment strategies for carbohydrates (i.e., cellulose, chitin and alginate) from bottom-up to top-down strategies are discussed, including the rapidly developed innovative technologies such as shear-induced orientation through extrusion-based 3D/4D printing, magnetic-assisted alignment, and electric-induced alignment. The unique properties and wide applications of anisotropic carbohydrate materials across different fields, from biomedical, biosensors, smart actuators, soft conductive materials, to thermal management are also summarized. Finally, recommendations on the selection of fabrication strategies are given. The major challenge lies in the construction of long-range hierarchical alignment with high orientation degree and precise control over complicated architectures. With the future development of hierarchical alignment strategies, alignment control techniques, and alignment mechanism elucidation, the potential of anisotropic carbohydrate materials for scalable manufacture and clinical applications will be fully realized.

Perspectives on the Novel Multifunctional Nerve Guidance Conduits: From Specific Regenerative Procedures to Motor Function Rebuilding

Peripheral nerve injury potentially destroys the quality of life by inducing functional movement disorders and sensory capacity loss, which results in severe disability and substantial psychological, social, and financial burdens. Autologous nerve grafting has been commonly used as treatment in the clinic; however, its rare donor availability limits its application. A series of artificial nerve guidance conduits (NGCs) with advanced architectures are also proposed to promote injured peripheral nerve regeneration, which is a complicated process from axon sprouting to targeted muscle reinnervation. Therefore, exploring the interactions between sophisticated NGC complexes and versatile cells during each process including axon sprouting, Schwann cell dedifferentiation, nerve myelination, and muscle reinnervation is necessary. This review highlights the contribution of functional NGCs and the influence of microscale biomaterial architecture on biological processes of nerve repair. Progressive NGCs with chemical molecule induction, heterogenous topographical morphology, electroactive, anisotropic assembly microstructure, and self-powered electroactive and magnetic-sensitive NGCs are also collected, and they are expected to be pioneering features in future multifunctional and effective NGCs.

Nanocellulose-based porous materials: Regulation and pathway to commercialization in regenerative medicine

We review the recent progress that have led to the development of porous materials based on cellulose nanostructures found in plants and other resources. In light of the properties that emerge from the chemistry, shape and structural control, we discuss some of the most promising uses of a plant-based material, nanocellulose, in regenerative medicine. Following a brief discussion about the fundamental aspects of self-assembly of nanocellulose precursors, we review the key strategies needed for material synthesis and to adjust the architecture of the materials (using three-dimensional printing, freeze-casted porous materials, and electrospinning) according to their uses in tissue engineering, artificial organs, controlled drug delivery and wound healing systems, among others. For this purpose, we map the structure-property-function relationships of nanocellulose-based porous materials and examine the course of actions that are required to translate innovation from the laboratory to industry. Such efforts require attention to regulatory aspects and market pull. Finally, the key challenges and opportunities in this nascent field are critically reviewed.

Tensile properties of freeze-cast collagen scaffolds: How processing conditions affect structure and performance in the dry and fully hydrated states

Tensile properties of directionally freeze-cast biopolymer scaffolds are rarely reported, even though they are of interest from a fundamental science perspective and critical in applications such as scaffolds for the regeneration of nerves or when used as ureteral stents. The focus of this study is on collagen scaffolds freeze-cast with two different applied cooling rates (10 °C/min and 1 °C/min) in two freezing directions (longitudinal and radial). Reported are the results of a systematic structural characterization of dry scaffolds by scanning electron microscopy and the mechanical characterization in tension of both dry and fully hydrated scaffolds. Systematic structure-property-processing correlations are obtained for a comparison of the tensile performance of longitudinally and radially freeze-cast collagen scaffolds with their performance in compression. Collated, the correlations, obtained both in tension in this study and in compression for collagen and chitosan in two earlier reports, not only enable the custom-design of freeze-cast biopolymer scaffolds for biomedical applications but also provide new insights into similarities and differences of scaffold and cell-wall structure formation during the directional solidification of "smooth" and "fibrillar" biopolymers.

Hierarchical structure formation by crystal growth-front instabilities during ice templating

Directional solidification of aqueous solutions and slurries in a temperature gradient is widely used to produce cellular materials through a phase separation of solutes or suspended particles between growing ice lamellae. While this process has analogies to the directional solidification of metallurgical alloys, it forms very different hierarchical structures. The resulting honeycomb-like porosity of freeze-cast materials consists of regularly spaced, lamellar cell walls which frequently exhibit unilateral surface features of morphological complexity reminiscent of living forms, all of which are unknown in metallurgical structures. While the strong anisotropy of ice-crystal growth has been hypothesized to play a role in shaping those structures, the mechanism by which they form has remained elusive. By directionally freezing binary water mixtures containing small solutes obeying Fickian diffusion, and phase-field modeling of those experiments, we reveal how those structures form. We show that the flat side of lamellae forms because of slow faceted ice-crystal growth along the c-axis, while weakly anisotropic fast growth in other directions, including the basal plane, is responsible for the unilateral features. Diffusion-controlled morphological primary instabilities on the solid-liquid interface form a cellular structure on the atomically rough side of the lamellae, which template regularly spaced "ridges" while secondary instabilities of this structure are responsible for the more complex features. Collating the results, we obtain a scaling law for the lamellar spacing,  [Formula: see text] , where [Formula: see text] and [Formula: see text] are the local growth rate and temperature gradient, respectively.

Understanding Nanocellulose-Water Interactions: Turning a Detriment into an Asset

Modern technology has enabled the isolation of nanocellulose from plant-based fibers, and the current trend focuses on utilizing nanocellulose in a broad range of sustainable materials applications. Water is generally seen as a detrimental component when in contact with nanocellulose-based materials, just like it is harmful for traditional cellulosic materials such as paper or cardboard. However, water is an integral component in plants, and many applications of nanocellulose already accept the presence of water or make use of it. This review gives a comprehensive account of nanocellulose-water interactions and their repercussions in all key areas of contemporary research: fundamental physical chemistry, chemical modification of nanocellulose, materials applications, and analytical methods to map the water interactions and the effect of water on a nanocellulose matrix.

Nanocellulose-gellan cross-linked scaffolds for vaginal delivery of fluconazole

The objective of this research is to formulate lyophilized fluconazole-loaded nanocellulose-gellan scaffolds cross-linked using trisodium trimetaphosphate as a vaginal drug delivery system. The effect of polymers (nanocellulose and gellan gum) and cross-linking agents on drug release and mucoadhesive strength were determined by approaching a two-factor three-level central composite experimental design. The optimal formulation of the fluconazole-loaded cross-linked rice or wheat nanocellulose-gellan based scaffolds comprised of the concentration of polymers (4.91 % w/v or 4.99 % w/v) and trisodium trimetaphosphate (16.43 % w/v or 15.83 % w/v), respectively. The infrared spectra confirmed the cross-linking of nanocellulose and gellan gum while the thermal graph revealed the higher thermal stability of cross-linked scaffolds. The diffractogram of the scaffolds unveiled their amorphous nature while the electron micrographs depict the porous nature of the fluconazole-loaded nanocellulose-gellan scaffolds. The phosphorylated cross-linked nanocellulose-gellan scaffolds represent more swelling (8-fold higher), porosity (>83 %), tensile strength (>34 MPa), and mucoadhesive strength (>1940 mN), and less enzymatic degradation rate over the non cross-linked scaffolds. The optimal batch of cross-linked nanocellulose-gellan scaffolds provided a sustained release of 99 % of fluconazole over 24 h with 1.19-fold higher ex-vivo vaginal permeation over the native scaffolds. In addition, the phosphorylated nanocellulose-gellan based scaffolds exhibit improved antifungal activity and non-cytotoxicity.

3D-Printing of Silk Nanofibrils Reinforced Alginate for Soft Tissue Engineering

The main challenge of extrusion 3D bioprinting is the development of bioinks with the desired rheological and mechanical performance and biocompatibility to create complex and patient-specific scaffolds in a repeatable and accurate manner. This study aims to introduce non-synthetic bioinks based on alginate (Alg) incorporated with various concentrations of silk nanofibrils (SNF, 1, 2, and 3 wt.%) and optimize their properties for soft tissue engineering. Alg-SNF inks demonstrated a high degree of shear-thinning with reversible stress softening behavior contributing to extrusion in pre-designed shapes. In addition, our results confirmed the good interaction between SNFs and alginate matrix resulted in significantly improved mechanical and biological characteristics and controlled degradation rate. Noticeably, the addition of 2 wt.% SNF improved the compressive strength (2.2 times), tensile strength (5 times), and elastic modulus (3 times) of alginate. In addition, reinforcing 3D-printed alginate with 2 wt.% SNF resulted in increased cell viability (1.5 times) and proliferation (5.6 times) after 5 days of culturing. In summary, our study highlights the favorable rheological and mechanical performances, degradation rate, swelling, and biocompatibility of Alg-2SNF ink containing 2 wt.% SNF for extrusion-based bioprinting.

Chitosan-based coatings with tunable transparency and superhydrophobicity: A solvent-free and fluorine-free approach by stearoyl derivatization

One of the current greatest challenges in materials science and technology is the development of safe- and sustainable-by-design coatings with enhanced functionalities, e.g. to substitute fluorinated substances raising concerns for their potential hazard on human health. Bio-based polymeric coatings represent a promising route with a high potential. In this study, we propose an innovative sustainable method for fabricating coatings based on chitosan with modified functionality, with a fine-tuning of coating properties, namely transparency and superhydrophobicity. The process consists in two main steps: i) fluorine-free modification of chitosan functional groups with stearoyl chloride and freeze-drying to obtain a superhydrophobic powder, ii) coating deposition using a novel solvent-free approach through a thermal treatment. The modified chitosan is characterized to assess its chemico-physical properties and confirm the functionality modification with fatty acid tails. The deposition method enables tuning the coating properties of transparency and superhydrophobicity, maintaining good durability.

Regulation of hydrogen bonding network between cellulose nanofibers by rare earth ion Y3

Cellulose is regarded as the most abundant biomass, and nanocellulose derived from it has numerous applications in environmentally friendly materials. However, owing to the abundant hydroxyl groups on surface, nanocellulose is prone to agglomeration when transported, stored, or made into materials, which destroys material performance and limits its use. In this study, a feasible method was presented for regulating the hydrogen bonding strength between cellulose nanofibers (CNFs) by adding a minute quantity of rare earth ions Y³⁺ during cellulose nanofibrillation. It was found that the strength of hydrogen bonding between CNFs can be regulated by controlling the quantity of Y³⁺ in the system. The dispersibility and stability of CNFs, as well as the mechanical properties of CNFs films and CNFs-reinforced papers can be improved by 43.07 % and by 64.05 % after adding only 0.05 or 0.075 wt% Y³⁺. The possible mechanism of CNFs hydrogen bonding network reconstruction was proposed.

Chitosan Nanocomposites as Wound Healing Materials: Advances in Processing Techniques and Mechanical Properties

This review discusses the increasing potential of chitosan nanocomposites as viable materials capable of targeting these debilitating factors. This review focuses on various techniques used to process chitosan nanocomposites and their mechanical properties. Chitosan nanocomposites are regarded as highly effective antimicrobials for the treatment of chronic wounds. Chitosan nanocomposites, such as chitosan/polyethylene and oxide/silica/ciprofloxacin, demonstrate efficient antibacterial activity and exhibit no cytotoxicity against Human Foreskin Fibroblast Cell Lines (HFF2). Other studies have also showcased the capacity of chitosan nanocomposites to accelerate and improve tissue regeneration through increment in the number of fibroblast cells and angiogenesis and reduction of the inflammation phase. The layer-by-layer technique has benefits, ensuring its suitability in preparing chitosan nanocomposites for drug delivery and wound dressing applications. While the co-precipitation route requires a cross-linker to achieve stability during processing, the solution-casting route can produce stable chitosan nanocomposites without a cross-linker. By using the solution casting method, fillers such as multi-walled carbon nanotubes (MWCNTs) and halloysite nanotubes (HTs) can be uniformly distributed in the chitosan, leading to improved mechanical properties. The antibacterial effects can be achieved with the introduction of AgNPs or ZnO. With the increasing understanding of the biological mechanisms that control these diseases, there is an influx in the introduction of novel materials into the mainstream wound care market.

Preparation and properties of chitin/silk fibroin biocompatible composite fibers

In the present world chitin is used enormously in various fields, such as biopharmaceuticals, medical and clinical bioproducts, food packaging, etc. However, its development has been curbed by the impaired performance and cumbersome dissolution process when chitin materials are dissolved and regenerated by physical or chemical methods. To further obtain the regenerated chitin fiber material with improved performance, silk fibroin was introduced into the chitin matrix material, and chitin/silk fibroin biocompatible composite fibers were obtained by formic acid/calcium chloride/ethanol ternary system and top-down wet spinning technology. The produced composite fibers outperformed previously reported chitin-silk composites in terms of the tensile strength (160 MPa) and failure strain (25%). The fibers also performed good cell compatibility and strong cellular affinity for non-toxicity. The cell viabilities of the fibers were about 20% greater than those of silk fiber after three days of co-culture with NIH-3T3. Furthermore, no hemolysis occurs in the presence of chitin/silk fibers, demonstrating their superior hemocompatibility. The fibers had a hemolysis index as low as 1%, which is far lower than the acceptable level of 5%. The material offers prospective opportunities for biomaterial applications in anticoagulation, absorbable surgical sutures, etc.

Hierarchical Structure of Cellulose Nanofibril-Based Foams Explored by Multimodal X-ray Scattering

Structural characterization techniques are fundamental to correlate the material macro-, nano-, and molecular-scale structures to their macroscopic properties and to engineer hierarchical materials. Here, we combine X-ray transmission with scanning small- and wide-angle X-ray scattering (sSWAXS) to investigate ultraporous and lightweight biopolymer-based foams using cellulose nanofibrils (CNFs) as building blocks. The power of multimodal sSWAXS for multiscale structural characterization of self-assembled CNFs is demonstrated by spatially resolved maps at the macroscale (foam density and porosity), at the nanoscale (foam structural compactness, CNF orientation in the foam walls, and CNF packing state), and at the molecular scale (cellulose crystallite dimensions). Specifically, we compare the impact of freeze-thawing-drying (FTD) fabrication steps, such as static/stirred freezing and thawing in ethanol/water, on foam structural hierarchy spanning from the molecular to the millimeter scale. As such, we demonstrate the potential of X-ray scattering imaging for hierarchical characterization of biopolymers.

Regioselective Protection and Deprotection of Nanocellulose Molecular Design Architecture: Robust Platform for Multifunctional Applications

Regioselectively substituted nanocellulose was synthesized by protecting the primary hydroxyl group. Herein, we took advantage of the different reactivities of primary and secondary hydroxyl groups to graft large capping structures. This study mainly focuses on regioselective installation of trityl protecting groups on nanocellulose chains. The elemental analysis and nuclear magnetic resonance spectroscopy of regioselectively substituted nanofibrillated cellulose (NFC) suggested that the trityl group was successfully grafted in the primary hydroxyl group with a degree of substitution of nearly 1. Hansen solubility parameters were employed, and the binary system composed of an ionic liquid and pyridine as a base was revealed to be the optimum condition for regioselective functionalization of nanocellulose. Interestingly, the dissolution of NFC in the ionic liquid and the subsequent deprotection process of NFC substrates hardly affected the crystalline structure of NFC (3.6% decrease in crystallinity). This method may provide endless possibilities for the design of advanced engineered nanomaterials with multiple functionalities. We envisage that this protection/deprotection approach may lead to a bright future for the fabrication of multifunctional devices based on nanocellulose.

Cationic, anionic and neutral polysaccharides for skin tissue engineering and wound healing applications

Today, chronic wound care and management can be regarded as a clinically critical issue. However, the limitations of current approaches for wound healing have encouraged researchers and physicians to develop more efficient alternative approaches. Advances in tissue engineering and regenerative medicine have resulted in the development of promising approaches that can accelerate wound healing and improve the skin regeneration rate and quality. The design and fabrication of scaffolds that can address the multifactorial nature of chronic wound occurrence and provide support for the healing process can be considered an important area requiring improvement. In this regard, polysaccharide-based scaffolds have distinctive properties such as biocompatibility, biodegradability, high water retention capacity and nontoxicity, making them ideal for wound healing applications. Their tunable structure and networked morphology could facilitate a number of functions, such as controlling their diffusion, maintaining wound moisture, absorbing a large amount of exudates and facilitating gas exchange. In this review, the wound healing process and the influential factors, structure and properties of carbohydrate polymers, physical and chemical crosslinking of polysaccharides, scaffold fabrication techniques, and the use of polysaccharide-based scaffolds in skin tissue engineering and wound healing applications are discussed.

Nanocellulose for peripheral nerve regeneration in rabbits using citric acid as crosslinker with chitosan and freeze/thawed PVA

This work investigates peripheral nerve regeneration using membranes consisting of pure chitosan (CHI), which was further blended with nanofibrillated cellulose, with citric acid as crosslinker, with posterior addition of polyvinyl alcohol, with subsequent freeze thawing. Nanocellulose improves the mechanical and thermal resistance, as well as flexibility of the film, which is ideal for the surgical procedure. The hydrogel presented a slow rate of swelling, which is adequate for cell and drug delivery. A series ofin vitrotests revealed to be non-toxic for neuronal Schwann cell from the peripheral nervous system of Rattus norvegicus, while there was a slight increase in toxicity if crosslink is performed-freeze-thaw. Thein vivoresults, using rabbits with a 5 mm gap nerve defect, revealed that even though pure CHI was able to regenerate the nerve, it did not present functional recovery with only the deep pain attribute being regenerated. When autologous implant was used jointly with the biomaterial membrane, as a covering agent, it revealed a functional recovery within 15 d when cellulose and the hydrogel were introduced, which was attributed to the film charge interaction that may help influence the neuronal axons growth into correct locations. Thus, indicating that this system presents ideal regeneration as nerve conduits.

A biodegradable, mechanically tunable micro-arc oxidation AZ91D-based composite implant with calcium phosphate/chitosan coating promotes long-term bone tissue regeneration

BACKGROUND

To reduce the biodegradable rate and develop the long-term osteogenic ability of magnesium (Mg) alloy, we prepared a new biodegradable micro arc oxidation AZ91D-based composite implant with calcium phosphate/chitosan coating (CaP-CS/MAO/AZ91D) and investigated its mechanical property and long-term bone tissue regeneration ability.

MAIN METHODS AND MAJOR RESULTS

The results showed that the binding force and bioactivity of CaP-CS/MAO/AZ91D was better when the ratio of water to ethanol was 4:6 and MAO constant current was 0.1 A cm^-2 . Compressive strengths of 4:6 sample were more than 1300 N when the soaking time was increased to 21 days. CaP-CS/MAO/AZ91D extracts promoted differentiation and proliferation of rat mesenchymal stem cells (RMSC), which achieved higher proliferation rates over 16 days of culture and exhibited early alkaline phosphatase activity and late bone sialoprotein markers.

CONCLUSIONS AND IMPLICATIONS

CaP-CS/MAO/AZ91D was established to promote RMSC osteogenic differentiation within a proper range for at least 90 days through Wnt/β-catenin pathway activation, which would allow sufficient time for bone healing. Collectively, our findings suggest that the CaP-CS/MAO/AZ91D coating could not only reduce the corrosion rate and lead to better long-term biocompatibility but also promote osteogenic mineralization.

Ice Templating Soft Matter: Fundamental Principles and Fabrication Approaches to Tailor Pore Structure and Morphology and Their Biomedical Applications

Porous scaffolds are widely used in biomedical applications where pore size and morphology influence a range of biological processes, including mass transfer of solutes, cellular interactions and organization, immune responses, and tissue vascularization, as well as drug delivery from biomaterials. Ice templating, one of the most widely utilized techniques for the fabrication of porous materials, allows control over pore morphology by controlling ice formation in a suspension of solutes. By fine-tuning freezing and solute parameters, ice templating can be used to incorporate pores with tunable morphological features into a wide range of materials using a simple, accessible, and scalable process. While soft matter is widely ice templated for biomedical applications and includes commercial and clinical products, the principles underpinning its ice templating are not reviewed as well as their inorganic counterparts. This review describes and critically evaluates fundamental principles, fabrication and characterization approaches, and biomedical applications of ice templating in polymer-based biomaterials. It describes the utility of porous scaffolds in biomedical applications, highlighting biological mechanisms impacted by pore features, outlines the physical and thermodynamic mechanisms underpinning ice templating, describes common fabrication setups, critically evaluates complexities of ice templating specific to polymers, and discusses future directions in this field.

Structure-property-processing correlations of longitudinal freeze-cast chitosan scaffolds for biomedical applications

Needed for the custom-design of longitudinally freeze-cast chitosan scaffolds for biomedical applications are systematic structure-property-processing correlations. Combining mechanical testing in compression with both scanning electron microscopy and semiautomated confocal microscopy for a quantitative structural characterization of fully hydrated chitosan scaffolds, robust correlations were determined. Decreasing the applied cooling rate from 10 °C/min to 0.1 °C/min, the short and long axes of the pore cross-sections, the pore aspect ratio, and the pore area were found to increase from 68.0 μm to 120.5 μm, from 189.2 μm to 401.2 μm, from 2.64 to 3.52, and from 8,922 μm² to 35,596 μm², respectively. Values for the scaffolds' modulus, yield strength, and toughness range from 1,067 kPa to 3,209 kPa, from 37.7 kPa to 75.5 kPa, and from 20.3 kJ/m³ to 35.3 kJ/m³, respectively. Because of additional structural features, such as cell wall stiffening ridges, affecting the mechanical properties, not linear but more complex correlation with modulus, yield strength, and toughness were observed. Contrasting the results of this study with those obtained in an earlier study of dry and fully hydrated collagen scaffolds, we were able to identify features that are important and peculiar to each material system. Highlighted in this study are newly determined robust structure-property-processing correlations as well as processing conditions and features that are critical for the mechanical performance of chitosan and other biopolymer scaffolds made by freeze casting for biomedical applications.

Osteoblast cell viability over ultra-long tricalcium phosphate nanocrystal-based methacrylate chitosan composite for bone regeneration

Bio-ceramic morphology plays a crucial role in bone repair and regeneration. It is extensively utilized in bone scaffold synthesis due to its better biological system activity and biocompatibility. Here, the ultra-long tricalcium phosphate (UTCP) was synthesized with the assistance of the ultrasonication method. The UTCP is modified as a scaffold by the reinforcement of methacrylate chitosan (MAC) polymer. The functionality of UTCP, UTCP combined MAC, methotrexate (MTX) loaded composites was characterized through FTIR (Fourier transform infrared spectroscopy). The crystalline natures are investigated by the XRD (X-ray diffraction), and results shows the ultra-long tricalcium phosphate crystalline phase is not altered after the reinforcement of MAC polymer and loading of MTX drugs. The morphological analyses were observed through electron microscopic analysis, and rod, polymer-coated rod structures were observed. The UTCP/MAC composite mechanical stress was increased from 1813 Pa of UTCP to 4272 Pa. The MTX loading and release was achieved 79.0 % within 3 h and 76.15 % at 20 h respectively. The UTCP/MAC and UTCP/MAC/MTX's viability investigated osteoblast like the cells (MG-63), and the MTX loaded UTCP/MAC composite exhibits good viability behaviors up to 96.0 % in 14 days. The results confirm the higher compatibility of the composite and profitable cell growth. It may be suitable for bone implantation preparation and it helps in faster regeneration of bone tissue after the in-vivo and clinical evaluation.

Development of Inula graveolens (L.) Plant Extract Electrospun/Polycaprolactone Nanofibers: A Novel Material for Biomedical Application

Recently, there has been a growing interest in research on nanofibrous scaffolds developed by electrospinning bioactive plant extracts. In this study, the extract material obtained from the medicinal plant Inula graveolens (L.) was loaded on polycaprolactone (PCL) electrospun polymeric nanofibers. The combined mixture was prepared by 5% of I. graveolens at 8% (PCL) concentration and electrospun under optimal conditions. The chemical analysis, morphology, and crystallization of polymeric nanofibers were carried out by (FT-IR) spectrometer, scanning electron microscopy (SEM), and XRD diffraction. Hydrophilicity was determined by a contact angle experiment. The strength was characterized, and the toxicity of scaffolds on the cell line of fibroblasts was finally investigated. The efficiency of nanofibers to enhance the proliferation of fibroblasts was evaluated in vitro using the optimal I. graveolens/PCL solutions. The results show that I. graveolens/PCL polymeric scaffolds exhibited dispersion in homogeneous nanofibers around 72 ± 963 nm in the ratio 70/30 (V:V), with no toxicity for cells, meaning that they can be used for biomedical applications.

Natural silk nanofibrils as reinforcements for the preparation of chitosan-based bionanocomposites

Nanofibrils derived from natural biopolymers have received extensive interest due to their exceptional mechanical properties and excellent biocompatibility. To fabricate biocompatible chitosan nanocomposites with high mechanical performance, silkworm silks were deconstructed into nanofibrils as structural and mechanical reinforcement of chitosan. After dispersing silk nanofibrils in chitosan solution, a set of nanocomposites, including film, porous scaffold, filament, and nanofibrous sponge, could be fabricated from the blended solutions. Silk nanofibrils could be uniformly dispersed in chitosan solution, and formed multi-dimensional nanocomposites. The nanocomposites exhibited enhanced mechanical strength and thermal stability, and provided a biomimetic nanofibrous structure for biomaterial applications. The enhancement in mechanical properties can be attributed to the interaction between the nanofibril phase and the chitosan matrix. As the polysaccharide/protein bionanocomposites derived from natural biopolymers, these materials offer new opportunities for biomaterial application by virtue of their biocompatibility and biodegradability, as well as enhanced mechanical properties and controllable mesoscopic structure.

2D and 3D graphical datasets for bamboo-inspired tubular scaffolds with functional gradients: micrographs and tomograms

Presented in this article are 2D and 3D graphical datasets in the form of micrographs and tomograms that were obtained as part of a systematic microstructural characterization by scanning electron microscopy and X-ray microtomography to illustrate freeze-cast bamboo-inspired tubular scaffolds with functional gradients ("Bamboo-inspired Tubular Scaffolds with Functional Gradients" [1]). Four material combinations of the coaxial 'core-shell' molds and their two end pieces were used to freeze cast highly porous tubes (Tube/Rod/Holder): ASA (Aluminum, 316 Stainless Steel, Aluminum), ASP (Aluminum, 316 Stainless Steel, Epoxy (Plastic)), SCA (316 Stainless Steel, Copper, Aluminum), and CSP (Copper, 316 Stainless Steel, Epoxy (Plastic)). Three techniques were used to coat the best performing CSP freeze-cast tubes: spray freezing (SF), spray coating (SC), and brush freezing (BF). The structure and density profile of the uncoated and coated tubes was quantified using X-ray microtomography and their functional gradients, and the resulting mechanical performance in bending were determined and compared. The structure-property-processing correlations determined for the coated and uncoated coaxially freeze cast tubular scaffolds offer strategies for the biomimetic design of bamboo-inspired porous tubes, which emulate bamboo's stiff outer shell supported by a porous, elastic inner layer to delay the onset of ovalization and failure, thereby increasing the tubes' mechanical efficiency.

A review of multifunctional nacre-mimetic materials based on bidirectional freeze casting

Nacre has achieved an excellent combination of strength and toughness through its unique brick-and-mortar structure of layered aragonite platelets bonded with biopolymers. Mimicking nacre has been considered as a practical way for the development of high-performance structural composites. Over the past years, many techniques have been developed to fabricate multifunctional nacre-mimetic materials, including freeze casting, layer-by-layer assembly, vacuum filtration, 3D printing and so on. Among them, freeze casting, especially bidirectional freeze casting, as an environmentally friendly and scalable method, has attracted extensive attention recently. In this review, we begin with the introduction and discussion of various fabrication techniques comparing their advantages and disadvantages, focusing on the most recent advances of the bidirectional freeze casting technique. Then, we summarize representative examples of applying the bidirectional freeze casting technique to assemble various building blocks into multifunctional nacre-mimetic materials and their wide applications. At the end, we discuss the future direction of using bidirectional freeze casting to make nacre-mimetic materials.