Polycaprolactone/polyvinylpyrrolidone coaxial electrospun fibers containing veratric acid-loaded chitosan nanoparticles for bone regeneration

Techniques and applications in 3D bioprinting with chitosan bio-inks for drug delivery: A review

Three-dimensional bioprinting leverages computer-aided design to construct tissues and organs with specialized bioinks. A notable biomaterial for this purpose is chitosan, a natural polysaccharide sourced from crustacean exoskeletons. Chitosan's biocompatibility, biodegradability, non-toxicity, and ability to promote cell adhesion and proliferation make it an excellent component for bioinks. Initially, the rheological properties of chitosan presented challenges for its use in bioprinting. Enhancements in its printability and stability were achieved by integrating it with other natural or synthetic polymers, facilitating its successful application in bioprinting. Chitosan-based bioinks are particularly promising for controlled drug delivery. Incorporating pharmaceuticals directly into the bioink enables the printed structures to serve as localized, sustained-release systems. This approach offers multiple advantages, including precise drug delivery to targeted disease sites, increased therapeutic efficiency, and reduced systemic side effects. Moreover, bioprinting allows for the customization of drug delivery mechanisms to meet individual patient requirements. Although there have been considerable advancements, the use of chitosan-based bioinks in drug delivery is still an emerging field. This review highlights chitosan's essential role in both systemic and localized drug delivery, underscoring its significance and discussing ongoing trends in its application for pharmaceutical purposes.

Chitosan alchemy: transforming tissue engineering and wound healing

Chitosan, a biopolymer acquired from chitin, has emerged as a versatile and favorable material in the domain of tissue engineering and wound healing. Its biocompatibility, biodegradability, and antimicrobial characteristics make it a suitable candidate for these applications. In tissue engineering, chitosan-based formulations have garnered substantial attention as they have the ability to mimic the extracellular matrix, furnishing an optimal microenvironment for cell adhesion, proliferation, and differentiation. In the realm of wound healing, chitosan-based dressings have revealed exceptional characteristics. They maintain a moist wound environment, expedite wound closure, and prevent infections. These formulations provide controlled release mechanisms, assuring sustained delivery of bioactive molecules to the wound area. Chitosan's immunomodulatory properties have also been investigated to govern the inflammatory reaction during wound healing, fostering a balanced healing procedure. In summary, recent progress in chitosan-based formulations portrays a substantial stride in tissue engineering and wound healing. These innovative approaches hold great promise for enhancing patient outcomes, diminishing healing times, and minimizing complications in clinical settings. Continued research and development in this field are anticipated to lead to even more sophisticated chitosan-based formulations for tissue repair and wound management. The integration of chitosan with emergent technologies emphasizes its potential as a cornerstone in the future of regenerative medicine and wound care. Initially, this review provides an outline of sources and unique properties of chitosan, followed by recent signs of progress in chitosan-based formulations for tissue engineering and wound healing, underscoring their potential and innovative strategies.

Tunable mechanical properties of chitosan-based biocomposite scaffolds for bone tissue engineering applications: A review

Bone tissue engineering (BTE) aims to develop implantable bone replacements for severe skeletal abnormalities that do not heal. In the field of BTE, chitosan (CS) has become a leading polysaccharide in the development of bone scaffolds. Although CS has several excellent properties, such as biodegradability, biocompatibility, and antibacterial properties, it has limitations for use in BTE because of its poor mechanical properties, increased degradation, and minimal bioactivity. To address these issues, researchers have explored other biomaterials, such as synthetic polymers, ceramics, and CS coatings on metals, to produce CS-based biocomposite scaffolds for BTE applications. These CS-based biocomposite scaffolds demonstrate superior properties, including mechanical characteristics, such as compressive strength, Young's modulus, and tensile strength. In addition, they are compatible with neighboring tissues, exhibit a controlled rate of degradation, and promote cell adhesion, proliferation, and osteoblast differentiation. This review provides a brief outline of the recent progress in making different CS-based biocomposite scaffolds and how to characterize them so that their mechanical properties can be tuned using crosslinkers for bone regeneration.

Plant molecules reinforce bone repair: Novel insights into phenol-modified bone tissue engineering scaffolds for the treatment of bone defects

Bone defects have become a major cause of disability and death. To overcome the limitations of natural bone implants, including donor shortages and immune rejection risks, bone tissue engineering (BTE) scaffolds have emerged as a promising therapy for bone defects. Despite possessing good biocompatibility, these metal, ceramic and polymer-based scaffolds are still challenged by the harsh conditions in bone defect sites. ROS accumulation, bacterial infection, excessive inflammation, compromised blood supply deficiency and tumor recurrence negatively impact bone tissue cells (BTCs) and hinder the osteointegration of BTE scaffolds. Phenolic compounds, derived from plants and fruits, have gained growing application in treating inflammatory, infectious and aging-related diseases due to their antioxidant ability conferred by phenolic hydroxyl groups. The prevalent interactions between phenols and functional groups also facilitate their utilization in fabricating scaffolds. Consequently, phenols are increasingly incorporated into BTE scaffolds to boost therapeutic efficacy in bone defect. This review demonstrated the effects of phenols on BTCs and bone defect microenvironment, summarized the intrinsic mechanisms, presented the advances in phenol-modified BTE scaffolds and analyzed their potential risks in practical applications. Overall, phenol-modified BTE scaffolds hold great potential for repairing bone defects, offering novel patterns for BTE scaffold construction and advancing traumatological medicine.

Co- and Triaxial Electrospinning for Stem Cell-based Bone Regeneration

Bone tissue is composed of organic minerals and cells. It has the capacity to heal for certain minor damages, but when the bone defects surpass the critical threshold, they need fixing. Bone regeneration through natural and synthetic biodegradable materials requires various steps, such as manufacturing methods and materials selection. A successful biodegradable bone graft should have a high surface area/ volume ratio, strength, and a biocompatible, porous structure capable of promoting cell adhesion, proliferation, and differentiation. Considering these requirements, the electrospinning technique is promising for creating functional nano-sized scaffolds. The multi-axial methods, such as coaxial and triaxial electrospinning, are the most popular techniques to produce double or tri-layered scaffolds, respectively. Recently, stem cell culture on scaffolds and the application of osteogenic differentiation protocols on these scaffolds have opened new possibilities in the field of biomaterials research. This review discusses an overview of the progress in coaxial and triaxial technology through biodegradable composite bone materials. The review also carefully elaborates the osteogenic differentiation using stem cells and their performance with nano-sized scaffolds.

Investigations into the effects of scaffold microstructure on slow-release system with bioactive factors for bone repair

In recent years, bone tissue engineering (BTE) has played an essential role in the repair of bone tissue defects. Although bioactive factors as one component of BTE have great potential to effectively promote cell differentiation and bone regeneration, they are usually not used alone due to their short effective half-lives, high concentrations, etc. The release rate of bioactive factors could be controlled by loading them into scaffolds, and the scaffold microstructure has been shown to significantly influence release rates of bioactive factors. Therefore, this review attempted to investigate how the scaffold microstructure affected the release rate of bioactive factors, in which the variables included pore size, pore shape and porosity. The loading nature and the releasing mechanism of bioactive factors were also summarized. The main conclusions were achieved as follows: i) The pore shapes in the scaffold may have had no apparent effect on the release of bioactive factors but significantly affected mechanical properties of the scaffolds; ii) The pore size of about 400 μm in the scaffold may be more conducive to controlling the release of bioactive factors to promote bone formation; iii) The porosity of scaffolds may be positively correlated with the release rate, and the porosity of 70%-80% may be better to control the release rate. This review indicates that a slow-release system with proper scaffold microstructure control could be a tremendous inspiration for developing new treatment strategies for bone disease. It is anticipated to eventually be developed into clinical applications to tackle treatment-related issues effectively.

Nanoparticle Synthesis and Their Integration into Polymer-Based Fibers for Biomedical Applications

The potential of nanoparticles as effective drug delivery systems combined with the versatility of fibers has led to the development of new and improved strategies to help in the diagnosis and treatment of diseases. Nanoparticles have extraordinary characteristics that are helpful in several applications, including wound dressings, microbial balance approaches, tissue regeneration, and cancer treatment. Owing to their large surface area, tailor-ability, and persistent diameter, fibers are also used for wound dressings, tissue engineering, controlled drug delivery, and protective clothing. The combination of nanoparticles with fibers has the power to generate delivery systems that have enhanced performance over the individual architectures. This review aims at illustrating the main possibilities and trends of fibers functionalized with nanoparticles, focusing on inorganic and organic nanoparticles and polymer-based fibers. Emphasis on the recent progress in the fabrication procedures of several types of nanoparticles and in the description of the most used polymers to produce fibers has been undertaken, along with the bioactivity of such alliances in several biomedical applications. To finish, future perspectives of nanoparticles incorporated within polymer-based fibers for clinical use are presented and discussed, thus showcasing relevant paths to follow for enhanced success in the field.

Recent Advancements in Electrospun Chitin and Chitosan Nanofibers for Bone Tissue Engineering Applications

Treatment of large segmental bone loss caused by fractures, osteomyelitis, and non-union results in expenses of around USD 300,000 per case. Moreover, the worst-case scenario results in amputation in 10% to 14.5% of cases. Biomaterials, cells, and regulatory elements are employed in bone tissue engineering (BTE) to create biosynthetic bone grafts with effective functionalization that can aid in the restoration of such fractured bones, preventing amputation and alleviating expenses. Chitin (CT) and chitosan (CS) are two of the most prevalent natural biopolymers utilized in the fields of biomaterials and BTE. To offer the structural and biochemical cues for augmenting bone formation, CT and CS can be employed alone or in combination with other biomaterials in the form of nanofibers (NFs). When compared with several fabrication methods available to produce scaffolds, electrospinning is regarded as superior since it enables the development of nanostructured scaffolds utilizing biopolymers. Electrospun nanofibers (ENFs) offer unique characteristics, including morphological resemblance to the extracellular matrix, high surface-area-to-volume ratio, permeability, porosity, and stability. This review elaborates on the recent strategies employed utilizing CT and CS ENFs and their biocomposites in BTE. We also summarize their implementation in supporting and delivering an osteogenic response to treat critical bone defects and their perspectives on rejuvenation. The CT- and CS-based ENF composite biomaterials show promise as potential constructions for bone tissue creation.

Chitosan-coated and thymol-loaded polymeric semi-interpenetrating hydrogels: An effective platform for bioactive molecule delivery and bone regeneration in vivo

Thymol (2-isopropyl-5-methylphenol; Thy) is a monoterpene phenolic phytocompound with medicinal properties; however, its impact on osteogenesis is yet to be thoroughly investigated. Its distribution is often hampered because of its intricate hydrophobic structure, which reduces its bioavailability. In this study, we synthesized a drug delivery vehicle using semi-interpenetrating polymer network (SIPN) hydrogels containing sodium alginate and poly(2-ethyl-2-oxazoline) (SA/Pox) loaded with Thy at varying concentrations (100, 150, and 200 μM). Subsequently, they were coated with chitosan (CS) to increase bioactivity and for sustained and prolonged release of Thy. Thy-loaded CS-coated SIPN hydrogels (SA/Pox/CS-Thy) were developed using ionic gelation and polyelectrolyte-complexation techniques. The addition of CS to hydrogels enhanced their physicochemical and material properties. These hydrogels were cytofriendly toward mouse mesenchymal stem cells (mMSCs). When mMSCs were cultured on hydrogels, Thy stimulated osteoblastic differentiation, as evidenced by calcium deposits at the cellular level. The expression of RUNX2, a key bone transcriptional factor, and other differentiation biomarkers was significantly enhanced in mMSCs cultured on SA/Pox/CS-Thy hydrogels. Notably, Thy in the SA/Pox/CS hydrogels significantly activated the TGF-β/BMP signaling pathway, which is involved in osteogenesis. A rat tibial bone defect model system revealed that the incorporation of Thy into SA/Pox/CS hydrogels augmented bone regeneration. Thus, sustained and prolonged release of Thy from the SA/Pox/CS hydrogels promoted osteoblast differentiation in vitro and bone formation in vivo. These findings shed light on the effect of Thy bioavailability in fostering osteoblast differentiation and its prospective application in bone rejuvenation.

Biocompatibility of Veratric Acid-Encapsulated Chitosan/Methylcellulose Hydrogel: Biological Characterization, Osteogenic Efficiency with In Silico Molecular Modeling

The limitations of graft material, and surgical sites for autografts in bone defects treatment have become a significant challenge in bone tissue engineering. Phytocompounds markedly affect bone metabolism by activating the osteogenic signaling pathways. The present study investigated the biocompatibility of the bio-composite thermo-responsive hydrogels consisting of chitosan (CS), and methylcellulose (MC) encapsulated with veratric acid (VA) as a restorative agent for bone defect treatment. The spectroscopy analyses confirmed the formation of CS/MC hydrogels and VA encapsulated CS/MC hydrogels (CS/MC-VA). Molecular analysis of the CS-specific MC decamer unit with VA complex exhibited a stable integration in the system. Further, Runx2 (runt-related transcription factor 2) was found in the docking mechanism with VA, indicating a high binding affinity towards the functional site of the Runx2 protein. The formulated CS/MC-VA hydrogels exhibited biocompatibility with the mouse mesenchymal stem cells, while VA promoted osteogenic differentiation in the stem cells, which was verified by calcium phosphate deposition through the von Kossa staining. The study results suggest that CS/MC-VA could be a potential therapeutic alternative source for bone regeneration.

Segregation of Benzoic Acid in Polymer Crystalline Cavities

Benzoic acid (BA) and its derivatives are very attractive because of their pharmacological properties, such as antioxidant, radical-regulating, antiviral, antitumor, anti-inflammatory, antimicrobial and antifungal. Syndiotactic polystyrene (sPS) and poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) films exhibiting co-crystalline phases with BA were prepared and characterized by WAXD, FTIR and polarized FTIR measurements. The FTIR measurements clearly showed that BA was present mainly as a dimer in the crystalline channels of the ε form of sPS as well as in the α form of PPO, as generally occurs not only in the solid state but also in organic dilute solutions. BA was instead present as isolated molecules in the crystalline cavities of the δ form of sPS. In fact, the FTIR spectra of BA guest molecules exhibited vibrational peaks close to those of BA in its vapor phase. Hence, the nanoporous-crystalline δ form of sPS not only avoids additive aggregation but also leads to the separation of dimeric molecules and the segregation of monomeric BA.

Fabrication of BMP-2-peptide-Deferoxamine- and QK-peptide-functionalized nanoscaffolds and their application for bone defect treatment

The microenvironment in the healing process of large bone defects requires suitable conditions to promote osteogenesis and angiogenesis. Coaxial electrospinning is a mature method in bone tissue engineering (BTE) and allows functional modification. Appropriate modification methods can be used to improve the bioactivity of scaffolds for BTE. In this study, coaxial electrospinning with QK peptide (a Vascular endothelial growth factor mimetic peptide) and BMP-2 peptide-DFO (BD) was performed to produce double-modified PQBD scaffolds with vascularizing and osteogenic features. The morphology of coaxially electrospun scaffolds was verified by scanning electron microscopy (SEM) and transmission electron microscopy. Laser scanning confocal microscopy and Fourier transform infrared spectroscopy confirmed that BD covalently bound to the surface of the P and PQ scaffolds. In vitro, the PQBD scaffold promoted the adhesion and proliferation of bone marrow stromal cells (BMSCs). Both QK peptide and BD showed sustainable release and preservation of biological activity, enhancing the osteogenic differentiation of BMSCs and the migration of human umbilical vein endothelial cells and promoting angiogenesis. The combined ability of these factors to promote osteogenesis and angiogenesis is superior to that of each alone. In vivo, the PQBD scaffold was implanted into the bone defect, and after 8 weeks, the defect area was almost completely covered by new bone tissue. Histology showed more mature bone tissue and more blood vessels. PQBD scaffolds promote both angiogenesis and osteogenesis, offering a promising approach to enhance bone regeneration in the treatment of large bone defects.

Scaffold Fabrication Techniques of Biomaterials for Bone Tissue Engineering: A Critical Review

Bone tissue engineering (BTE) is a promising alternative to repair bone defects using biomaterial scaffolds, cells, and growth factors to attain satisfactory outcomes. This review targets the fabrication of bone scaffolds, such as the conventional and electrohydrodynamic techniques, for the treatment of bone defects as an alternative to autograft, allograft, and xenograft sources. Additionally, the modern approaches to fabricating bone constructs by additive manufacturing, injection molding, microsphere-based sintering, and 4D printing techniques, providing a favorable environment for bone regeneration, function, and viability, are thoroughly discussed. The polymers used, fabrication methods, advantages, and limitations in bone tissue engineering application are also emphasized. This review also provides a future outlook regarding the potential of BTE as well as its possibilities in clinical trials.

Graphene oxide reinforced SrHAP composite as a drug carrier in bone regeneration

Strontium substituted HAP (SrHAP), with a 10 mol% substitution, was mineralized on increasing weight percentages of graphene oxide (2, 4 and 6). The GS composites were comprehensively characterized for drug delivery in bone reconstruction. The formation of SrHAP was verified by XRD and FT-IR results. The apatite crystallization was influenced by graphene oxide content and strontium. The EDS results confirmed the presence of strontium and HR-SEM depicted rod shape apatite, of length between 58 and 135 nm, uniformly embedded on graphene oxide. The reinforcement of graphene oxide increased the surface area, porosity, microhardness (upto 0.59 GPa), protein adsorption (upto 18.16 μg/mg), water uptake and degradation properties. Also, the increase in graphene oxide fraction significantly enhanced the curcumin encapsulation efficiency (upto 80.16%) and the drug release was considerably retarded over SrHAP. The in vitro studies using human osteoblast-like MG-63 cells demonstrated that curcumin-loaded composite was biocompatible and promoted proliferation, differentiation and matrix mineralization. The results highlight the combinational therapy of osteogenic ion (strontium) and osteogenic drug (curcumin) as a promising platform in bone tissue engineering.

Chitosan-based scaffolds as drug delivery systems in bone tissue engineering

The bone tissue engineering approach for treating large bone defects becomes necessary when the tissue damage surpasses the threshold of the inherent regenerative ability of the human body. A myriad of natural biodegradable polymers and scaffold fabrication techniques have emerged in the last decade. Chitosan (CS) is especially attractive as a bone scaffold material to support cell attachment and proliferation and mineralization of the bone matrix. The primary amino groups in CS are responsible for properties such as controlled drug release, mucoadhesion, in situ gelation, and transfection. CS-based smart drug delivery scaffolds that respond to environmental stimuli have been reported to have a localized sustained delivery of drugs in the large bone defect area. This review outlines the recent advances in the fabrication of CS-based scaffolds as a pharmaceutical carrier to deliver drugs such as antibiotics, growth factors, nucleic acids, and phenolic compounds for bone tissue regeneration.

Angiogenic and Osteogenic Effects of Flavonoids in Bone Regeneration

Bone is a highly vascularised tissue that relies on a close spatial and temporal interaction between blood vessels and bone cells. As a result, angiogenesis is critical for bone formation and healing. The vascular system supports bone regeneration by delivering oxygen, nutrients, and growth factors, as well as facilitating efficient cell-cell contact. Most clinical applications of engineered bone grafts are hampered by insufficient vascularization after implantation. Over the last decade, a number of flavonoids have been reported to have osteogenic-angiogenic potential in bone regeneration because of their excellent bioactivity, low cost, availability, and minimal in vivo toxicity. During new bone formation, the osteoinductive nature of certain flavonoids is involved in regulating multiple signaling pathways contributing toward the osteogenic-angiogenic coupling. This review briefly outlines the osteogenic-angiogenic potential of those flavonoids and the mechanisms of their action in promoting bone regeneration. However, further studies are needed to investigate their delivery strategies and establish their clinical efficacy. This article is protected by copyright. All rights reserved.

Orsellinic acid-loaded chitosan nanoparticles in gelatin/nanohydroxyapatite scaffolds for bone formation in vitro

AIM

Orsellinic acid (2,4-Dimethoxy-6-methylbenzoic acid) (OA) is a hydrophobic polyphenolic compound with therapeutic potential, but its impact on actuating osteogenesis remains unknown. The bioavailability of OA is hampered by its hydrophobic nature. This study aimed to fabricate nano-drug delivery system-based scaffolds for OA and test its potential for osteogenesis in vitro.

MATERIALS AND METHODS

OA was loaded into chitosan nanoparticles (nCS + OA) using the ionic gelation technique at different concentrations. nCS + OA were incorporated onto the scaffolds containing gelatin (Gel) and nanohydroxyapatite (nHAp) by the lyophilization method. Biocomposite scaffolds were examined for their physicochemical and material characteristic properties. The effect of OA in the scaffolds for osteoblast differentiation was determined by alizarin red and von Kossa staining at the cellular level and by reverse transcriptase-qPCR and western blot analysis at the molecular level.

KEY FINDINGS

The scaffolds showed excellent physiochemical and material characteristics and remained cyto-friendly to mouse mesenchymal stem cells (mMSCs, C3H10T1/2). The release of OA from Gel/nHAp/nCS scaffolds enhanced the differentiation of mMSCs towards osteoblasts, as observed through cellular and molecular studies. Moreover, the osteogenic potential of OA was mediated by the activation of FAK and ERK signaling pathways through integrins.

SIGNIFICANCE

The inclusion of OA into Gel/nHAp/nCS biocomposite scaffolds at 80 μM concentration promoted osteoblast differentiation via cell adhesion mediated signaling, compared with that shown by Gel/nHAp/nCS alone. Overall, this study identified the potential therapeutic OA containing Gel/nHAp/nCS scaffolds, accelerating its potential for clinical application towards bone regeneration.

Advancements in nucleic acids-based techniques for bone regeneration

The dynamic biology of bone involving an enormous magnitude of cellular interactions and signaling transduction provides ample biomolecular targets, which can be enhanced or repressed to mediate a rapid regeneration of the impaired bone tissue. The delivery of nucleic acids such as DNA and RNA can enhance the expression of osteogenic proteins. Members of the RNA interference pathway such as miRNA and siRNA can repress negative osteoblast differentiation regulators. Advances in nanomaterials have provided researchers with a plethora of delivery modules that can ensure proper transfection. Combining the nucleic acid carrying vectors with bone scaffolds has met with tremendous success in accomplishing bone formation. Recent years have witnessed the advent of CRISPR and DNA nanostructures in regenerative medicine. This review focuses on the delivery of nucleic acids and touches upon the prospect of CRISPR and DNA nanostructures for bone tissue engineering, emphasizing their potential in treating bone defects.

Fibers by Electrospinning and Their Emerging Applications in Bone Tissue Engineering

Bone tissue engineering (BTE) is an optimized approach for bone regeneration to overcome the disadvantages of lacking donors. Biocompatibility, biodegradability, simulation of extracellular matrix (ECM), and excellent mechanical properties are essential characteristics of BTE scaffold, sometimes including drug loading capacity. Electrospinning is a simple technique to prepare fibrous scaffolds because of its efficiency, adaptability, and flexible preparation of electrospinning solution. Recent studies about electrospinning in BTE are summarized in this review. First, we summarized various types of polymers used in electrospinning and methods of electrospinning in recent work. Then, we divided them into three parts according to their main role in BTE, (1) ECM simulation, (2) mechanical support, and (3) drug delivery system.

Three-dimensional-poly(lactic acid) scaffolds coated with gelatin/magnesium-doped nano-hydroxyapatite for bone tissue engineering

BACKGROUND

Treatment of critical-sized bone defects has progressively evolved over the years from metallic implants to more ingenious three-dimensional-based scaffolds. The use of three-dimensional scaffolds for bone regeneration from biodegradable polymers like poly(lactic acid) (PLA) is gaining popularity. Scaffolds with surface functionalization using gelatin (Gel) have the advantages of biocompatibility and cell adhesion. Nano-hydroxyapatite (nHAp) is one of the most promising implant materials utilized in orthopaedics. The osteogenic potential of the nHAp can be improved by the substitution of magnesium (Mg) ions onto the crystal lattice of nHAp. Thus, the goal of this work was to make three-dimensional-PLA scaffolds covered with Gel/Mg-nHAp for osteogenic effect.

METHODS AND RESULTS

The designed three-dimensional-PLA/Gel/Mg-nHAp scaffolds were attributed to various characterizations for the examination of their physicochemical, mechanical properties, cyto-compatibility, and biodegradability as well as their ability to promote osteogenesis in vitro. Mouse mesenchymal stem cells (mMSCs) were cytocompatible with these scaffolds. The osteogenic potential of three-dimensional-PLA/Gel/Mg-nHAp scaffolds employing mMSCs was validated at the cellular and molecular levels. The three-dimensional-PLA/Gel/Mg-nHAp scaffolds stimulated the differentiation of mMSCs towards osteoblastic lineage.

CONCLUSION

Based on these findings, we suggest that the three-dimensional-PLA/Gel/Mg-nHAp scaffolds' osteogenic capability may be advantageous in the mending of bone defects in orthopedic applications.

Chitin and chitosan on the nanoscale

In a matter of decades, nanomaterials from biomass, exemplified by nanocellulose, have rapidly transitioned from once being a subject of curiosity to an area of fervent research and development, now reaching the stages of commercialization and industrial relevance. Nanoscale chitin and chitosan, on the other hand, have only recently begun to raise interest. Attractive features such as excellent biocompatibility, antibacterial activity, immunogenicity, as well as the tuneable handles of their acetylamide (chitin) or primary amino (chitosan) functionalities indeed display promise in areas such as biomedical devices, catalysis, therapeutics, and more. Herein, we review recent progress in the fabrication and development of these bio-nanomaterials, describe in detail their properties, and discuss the initial successes in their applications. Comparisons are made to the dominant nanocelluose to highlight some of the inherent advantages that nanochitin and nanochitosan may possess in similar application.

Bioactivity of Chitosan-Based Particles Loaded with Plant-Derived Extracts for Biomedical Applications: Emphasis on Antimicrobial Fiber-Based Systems

Marine-derived chitosan (CS) is a cationic polysaccharide widely studied for its bioactivity, which is mostly attached to its primary amine groups. CS is able to neutralize reactive oxygen species (ROS) from the microenvironments in which it is integrated, consequently reducing cell-induced oxidative stress. It also acts as a bacterial peripheral layer hindering nutrient intake and interacting with negatively charged outer cellular components, which lead to an increase in the cell permeability or to its lysis. Its biocompatibility, biodegradability, ease of processability (particularly in mild conditions), and chemical versatility has fueled CS study as a valuable matrix component of bioactive small-scaled organic drug-delivery systems, with current research also showcasing CS’s potential within tridimensional sponges, hydrogels and sutures, blended films, nanofiber sheets and fabric coatings. On the other hand, renewable plant-derived extracts are here emphasized, given their potential as eco-friendly radical scavengers, microbicidal agents, or alternatives to antibiotics, considering that most of the latter have induced bacterial resistance because of excessive and/or inappropriate use. Loading them into small-scaled particles potentiates a strong and sustained bioactivity, and a controlled release, using lower doses of bioactive compounds. A pH-triggered release, dependent on CS’s protonation/deprotonation of its amine groups, has been the most explored stimulus for that control. However, the use of CS derivatives, crosslinking agents, and/or additional stabilization processes is enabling slower release rates, following extract diffusion from the particle matrix, which can find major applicability in fiber-based systems within ROS-enriched microenvironments and/or spiked with microbes. Research on this is still in its infancy. Yet, the few published studies have already revealed that the composition, along with an adequate drug release rate, has an important role in controlling an existing infection, forming new tissue, and successfully closing a wound. A bioactive finishing of textiles has also been promoting high particle infiltration, superior washing durability, and biological response.

Electrospinning for drug delivery applications: A review

Drug delivery devices are promising tools in the pharmaceutical field, as they are able to maximize the therapeutic effects of the delivered drug while minimizing the undesired side effects. In the past years, electrospun nanofibers attracted rising attention due to their unique features, like biocompatibility and broad flexibility. Incorporation of active principles in nanofibrous meshes proved to be an efficient method for in situ delivery of a wide range of drugs, expanding the possibility and applicability of those devices. In this review, the principle of electrospinning and different fields of applications are treated to give an overview of the recent literature, underlining the easy tuning and endless combination of this technique, that in the future could be the new frontier of personalized medicine.

Electrospun Janus Beads-On-A-String Structures for Different Types of Controlled Release Profiles of Double Drugs

A side-by-side electrospinning process characterized by a home-made eccentric spinneret was established to produce the Janus beads-on-a-string products. In this study, ketoprofen (KET) and methylene blue (MB) were used as model drugs, which loaded in Janus beads-on-a-string products, in which polyvinylpyrrolidone K90 (PVP K90) and ethyl cellulose (EC) were exploited as the polymer matrices. From SEM images, distinct nanofibers and microparticles in the Janus beads-on-a-string structures could be observed clearly. X-ray diffraction demonstrated that all crystalline drugs loaded in Janus beads-on-a-string products were transferred into the amorphous state. ATR-FTIR revealed that the components of prepared Janus nanostructures were compatibility. In vitro dissolution tests showed that Janus beads-on-a-string products could provide typical double drugs controlled-release profiles, which provided a faster immediate release of MB and a slower sustained release of KET than the electrospun Janus nanofibers. Drug releases from the Janus beads-on-a-string products were controlled through a combination of erosion mechanism (linear MB-PVP sides) and a typical Fickian diffusion mechanism (bead KET-EC sides). This work developed a brand-new approach for the preparation of the Janus beads-on-a-string nanostructures using side-by-side electrospinning, and also provided a fresh idea for double drugs controlled release and the potential combined therapy.

Synthesis and characterization of magnesium diboride nanosheets in alginate/polyvinyl alcohol scaffolds for bone tissue engineering

Boride, which belongs to the distinct category of ceramic materials, has attracted significant attention in tissue engineering applications. Magnesium diboride (MgB2) consists of a plane of magnesium atoms sandwiched between the layers of boron. Even though MgB2 showed its role in various applications, its effect on osteogenesis has not yet been investigated. In this study, we synthesized MgB2 nanosheets (MgB2NS), a new class of 2D-nanoscale structures, by the ultrasonication exfoliation method and incorporated them into a polymeric mixture of alginate (Alg) and polyvinyl alcohol (PVA) by the freeze-drying procedure. The synthesized scaffolds (Alg/PVA/MgB2NS) were characterized by SEM, XRD, FT-IR, protein adsorption, swelling, degradation, and biomineralization studies. These scaffolds were non-toxic to mouse mesenchymal stem cells (mMSCs). MgB2NS in the scaffolds enhanced osteoblast differentiation of mMSCs at the molecular level by the expression of Runx2 and osteoblast differentiation marker genes and at the cellular level by alkaline phosphatase, alizarin Red and von Kossa staining. Overall, our results showed that MgB2NS in Alg/PVA scaffolds have osteogenic potential, suggesting their possible use in bone tissue engineering applications.