Chitosan based nanofibers in bone tissue engineering

Chitosan as a tool for tissue engineering and rehabilitation: Recent developments and future perspectives - A review

Chitosan has established itself as a multifunctional and auspicious biomaterial within the domain of tissue engineering, presenting a decade of uninterrupted advancements and novel implementations. This article provides a comprehensive overview of the most recent developments in chitosan-based tissue engineering, focusing on significant progress made in the last ten years. An exploration is conducted of the various techniques utilized in the modification of chitosan and the production of scaffolds, with an analysis of their effects on cellular reactions and tissue regeneration. The investigation focuses on the integration of chitosan with other biomaterials and the addition of bioactive agents to improve their functionalities. Upon careful analysis of the in vitro and in vivo research, it becomes evident that chitosan effectively stimulates cell adhesion, proliferation, and differentiation. Furthermore, we offer valuable perspectives on the dynamic realm of chitosan-based approaches tailored to distinct tissue categories, including nerve, bone, cartilage, and skin. The review concludes with a discussion of prospective developments, with particular attention given to possible directions for additional study, translational implementations, and the utilization of chitosan to tackle existing obstacles in the field of tissue engineering. This extensive examination provides a significant amalgamation of the advancements achieved over the previous decade and directs scholars towards uncharted territories in chitosan-based tissue engineering.

Bioactive polymers: A comprehensive review on bone grafting biomaterials

The application of bone grafting materials in bone tissue engineering is paramount for treating severe bone defects. In this comprehensive review, we explore the significance and novelty of utilizing bioactive polymers as grafts for successful bone repair. Unlike metals and ceramics, polymers offer inherent biodegradability and biocompatibility, mimicking the native extracellular matrix of bone. While these polymeric micro-nano materials may face challenges such as mechanical strength, various fabrication techniques are available to overcome these shortcomings. Our study not only investigates diverse biopolymeric materials but also illuminates innovative fabrication methods, highlighting their importance in advancing bone tissue engineering.

Chitosan-based biomaterial delivery strategies for hepatocellular carcinoma

Background

Hepatocellular carcinoma accounts for 80% of primary liver cancers, is the most common primary liver malignancy. Hepatocellular carcinoma is the third leading cause of tumor-related deaths worldwide, with a 5-year survival rate of approximately 18%. Chemotherapy, although commonly used for hepatocellular carcinoma treatment, is limited by systemic toxicity and drug resistance. Improving targeted delivery of chemotherapy drugs to tumor cells without causing systemic side effects is a current research focus. Chitosan, a biopolymer derived from chitin, possesses good biocompatibility and biodegradability, making it suitable for drug delivery. Enhanced chitosan formulations retain the anti-tumor properties while improving stability. Chitosan-based biomaterials promote hepatocellular carcinoma apoptosis, exhibit antioxidant and anti-inflammatory effects, inhibit tumor angiogenesis, and improve extracellular matrix remodeling for enhanced anti-tumor therapy.

Methods

We summarized published experimental papers by querying them.

Results and Conclusions

This review discusses the physicochemical properties of chitosan, its application in hepatocellular carcinoma treatment, and the challenges faced by chitosan-based biomaterials.

Prospectives and challenges of nano-tailored biomaterials-assisted biological molecules delivery for tissue engineering purposes

Nano carriers have gained more attention for their possible medical and technological applications. Tailored nanomaterials can transport medications efficiently to targeted areas and allow for sustained medication discharge, reducing undesirable toxicities while boosting curative effectiveness. Nonetheless, transitioning nanomedicines from experimental to therapeutic applications has proven difficult, so different pharmaceutical incorporation approaches in nano scaffolds are discussed. Then numerous types of nanobiomaterials implemented as carriers and their manufacturing techniques are explored. This article is also supported by various applications of nanobiomaterials in the biomedical field.

Electrospun Composites of Chitosan with Cerium Oxide Nanoparticles for Wound Healing Applications: Characterization and Biocompatibility Evaluation In Vitro and In Vivo

Cerium oxide nanoparticles (CeONPs), as part of tissue regeneration matrices, can protect cells from reactive oxygen species and oxidative stress. In addition, they can influence the properties of the scaffold, including its electrospinnability and mechanical strength. In this work, we prepared electrospun fiber mats from a chitosan and polyethylene oxide blend (CS-PEO) with the addition of ceria nanoparticles (CS-PEO-CeONP). The addition of CeONPs resulted in a smaller fiber diameter and higher swelling compared to CS-PEO fiber mats. CeONP-modified fiber mats also had a higher Young's modulus due to the reinforcing effect of the nanoparticles. Both mats had comparable adhesion and cytocompatibility to mesenchymal stem cells, which had a more rounded morphology on CS-PEO-CeONP compared to elongated cells on the CS-PEO mats. Biocompatibility in an in vivo rat model showed no acute toxicity, no septic or allergic inflammation, and no rough scar tissue formation. The degradation of both mats passed the stage of matrix swelling. CS-PEO-CeONP showed significantly slower biodegradation, with most of the matrix remaining in the tissue after 90 days. The reactive inflammation was aseptic in nature with the involvement of multinucleated foreign-body type giant cells and was significantly reduced by day 90. CeONPs induced the formation of the implant's connective tissue capsule. Thus, the introduction of CeONPs influenced the physicochemical properties and biological activity of CS-PEO nanofiber mats.

Chitosan modified with PAP as a promising delivery system for melatonin in the treatment of osteoporosis: targeting the divalent metal transporter 1

The demands for novel and efficient therapies have gradually increased with the rising concerns of osteoporosis (OP). The most popular method in promoting bone regeneration during osteoporotic conditions consists of loading bioactive materials with different drugs to treat osteoporotic bones by either promoting the process of osteogenesis, or by inhibiting the activity of osteoclasts. By analyzing single cell sequencing results, we found that divalent metal transporter 1 (DMT1) played a role in OP. Based on our previous results, we found that melatonin (MT) suppressed expression of DMT1 induced by high glucose during OP, so we determined the efficacy of MT for the treatment of OP. However, the clinical effects of MT on OP were unsatisfactory. To enhance its biological efficacy, we combined MT with porous gelatin chitosan (chitosan) and the conductive material, PLA-b-AP-b-PLA (PAP), then determined how MT incorporation in chitosan@PAP nanoparticles affected the ability to promote MC3T3-E1 osteogenesis and mineralization, both in vitro and in vivo. The results confirmed the effect of MT on DMT1. We then prepared and characterized composites prepared as nanofibers, and determined the efficacy of MT combined with chitosan-PAP modified hydrogels as a slow-release system in a femur model of osteoporosis mice, with associated properties suitable for bone tissue engineering. The results indicated that MT-loaded chitosan@PAP nanospheres showed favorable osteogenic functions, both in vivo and in vitro, providing a practical solution for bone regeneration for OP patients.

Tailorable mechanical and degradation properties of KCl-reticulated and BDDE-crosslinked PCL/chitosan/κ-carrageenan electrospun fibers for biomedical applications: Effect of the crosslinking-reticulation synergy

The development of intricated and interconnected porous mats is desired for many applications in biomedicine and other relevant fields. The mats that comprise the use of natural, bioactive, and biodegradable polymers are the focus of current research activities. In the present work, crosslinked fibers with improved characteristics were produced by incorporating 1,4-butanediol diglycidyl ether (BDDE) into a polymer formulation containing polycaprolactone (PCL), chitosan (CS), and κappa-carrageenan (κ-C). A slight variation of formic acid (FA)/acetic acid (AA) ratio used as a solvent system, significantly affected the characteristics of the produced fiber mats. Both polysaccharides and BDDE played a major role in tailoring mechanical properties when fibrous scaffolds were reticulated under KCl-mediated basic conditions for determined periods of time at 50 °C. In vitro biological assessment of the electrospun fiber mats revealed proliferation of MC3T3-E1 cells when incubated for 1 and 7 days. After staining the cells with 4',6-diamidino-2-phenylindole (DAPI)/rhodamine phalloidin an autofluorescence response was observed by fluorescence microscopy in the scaffold manufactured using a solvent with higher FA/AA ratio due to the formation of microfibers. The results demonstrated the potential of the BDDE-crosslinked PCL/CS/κ-C electrospun fibers as promising materials for biomedical applications that may include soft and bone tissue regeneration.

Chitosan/MWCNTs nanocomposite coating on 3D printed scaffold of poly 3-hydroxybutyrate/magnetic mesoporous bioactive glass: A new approach for bone regeneration

The utilization of 3D printing has become increasingly common in the construction of composite scaffolds. In this study, magnetic mesoporous bioactive glass (MMBG) was incorporated into polyhydroxybutyrate (PHB) to construct extrusion-based 3D printed scaffold. After fabrication of the PHB/MMBG composite scaffolds, they were coated with chitosan (Cs) and chitosan/multi-walled carbon nanotubes (Cs/MWCNTs) solutions utilizing deep coating method. FTIR was conducted to confirm the presence of Cs and MWCNTs on the scaffolds' surface. The findings of mechanical analysis illustrated that presence of Cs/MWCNTs on the composite scaffolds increases compressive young modulus significantly, from 16.5 to 42.2 MPa. According to hydrophilicity evaluation, not only MMBG led to decrease the contact angle of pure PHB but also scaffolds surface modification utilization of Cs and MWCNTs, the contact angle decreased significantly from 82.34° to 54.15°. Furthermore, investigation of cell viability, cell metabolism and inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) and interleukin-10 (IL-10) and transforming growth factor-beta (TGF-β) proved that the scaffolds not only do not stimulate the immune system, but also polarize macrophage cells from M1 phase to M2 phase. The present study highlights the suitability of 3D printed scaffold PHB/MMBG with Cs/MWCNTs coating for bone tissue engineering.

Strong, elastic and degradation-tolerated hydrogels composed of chitosan, silk fibroin and bioglass nanoparticles with factor-bestowed activity for bone tissue engineering

Polymer hydrogels intended for use in bone repair need to be strong, elastic, and capable of enduring degradation. However, many natural polymer hydrogels lack these essential properties and thus, are unsuitable for bone repair applications. Here, a new type of multi-network hydrogel with improved mechanical and degradation-resistant properties has been developed for use in bone repair. The hydrogel is composed of thiolated chitosan (TCH), silk fibroin (SF), and thiolated bioglass (TBG) nanoparticles (NPs). The multi-networks are built through sulfhydryl self-crosslinking, diepoxide crosslinker-involved linkages of amino or hydroxyl groups, and enzyme-mediated phenol hydroxyl crosslinking. Additionally, mesoporous TBG NPs serve as a vehicle for loading stromal cell-derived factor-1 (SDF-1) to provide the gel with cell-recruiting activity. The formulated TCH/SF/TBG hydrogels exhibit remarkably enhanced strength, elasticity, and improved degradation tolerance compared to some gels made from only TCH or SF. Furthermore, TCH/SF/TBG gels can support the growth of seeded cells and the deposition of matrix components. Some TCH/SF/TBG gels also demonstrate the ability to release SDF-1 in an approximately linear manner for a few weeks while retaining the chemotactic properties of the released SDF-1. Overall, the multi-network hydrogel has the potential as an in situ forming material for cell-recruiting bone repair and regeneration.

Micropatterned Nanofiber Scaffolds of Salmon Gelatin, Chitosan, and Poly(vinyl alcohol) for Muscle Tissue Engineering

The development of scaffolds that mimic the aligned fibrous texture of the extracellular matrix has become an important requirement in muscle tissue engineering. Electrospinning is a widely used technique to fabricate biomimetic scaffolds. Therefore, a biopolymer blend composed of salmon gelatin (SG), chitosan (Ch), and poly(vinyl alcohol) (PVA) was developed by electrospinning onto a micropatterned (MP) collector, resulting in a biomimetic scaffold for seeding muscle cells. Rheology and surface tension studies were performed to determine the optimum solution concentration and viscosity for electrospinning. The scaffold microstructure was analyzed using SEM to determine the nanofiber's diameter and orientation. Blends of SG/Ch/PVA exhibited better electrospinnability and handling properties than pure PVA. The resulting scaffolds consist of a porous surface (∼46%), composed of a random fiber distribution, for a flat collector and scaffolds with regions of aligned nanofibers for the MP collector. The nanofiber diameters are 141 ± 2 and 151 ± 2 nm for the flat and MP collector, respectively. In vitro studies showed that myoblasts cultured on scaffold SG/Ch/PVA presented a high rate of cell growth. Furthermore, the aligned nanofibers on the SG/Ch/PVA scaffold provide a suitable platform for myoblast alignment.

Role and architectural significance of porous chitosan-based scaffolds in bone tissue engineering

In designing and fabricating scaffolds to fill the bone defects and stimulate new bone formation, the biomimetics of the construct is a crucial factor in invoking the bone microenvironment to promote osteogenic differentiation. Regarding structural traits, changes in porous characteristics of the scaffolds, such as pore size, pore morphology, and percentage porosity, may patronize or jeopardize their other physicochemical and biological properties. Chitosan (CS), a biodegradable naturally occurring polymer, has recently drawn considerable attention as a scaffolding material in tissue engineering and regenerative medicine. CS-based microporous scaffolds have been reported to aid osteogenesis under both in vitro and in vivo conditions by supporting cellular attachment and proliferation of osteoblast cells and the formation of mineralized bone matrix. This related notion may be found in numerous earlier research, even though the precise mechanism of action that encourages the development of new bone still needs to be understood completely. This article presents the potential correlations and the significance of the porous properties of the CS-based scaffolds to influence osteogenesis and angiogenesis during bone regeneration. This review also goes over resolving the mechanical limitations of CS by blending it with other polymers and ceramics.

Current application and modification strategy of marine polysaccharides in tissue regeneration: A review

Marine polysaccharides (MPs) are exceptional bioactive materials that possess unique biochemical mechanisms and pharmacological stability, making them ideal for various tissue engineering applications. Certain MPs, including agarose, alginate, carrageenan, chitosan, and glucan have been successfully employed as biological scaffolds in animal studies. As carriers of signaling molecules, scaffolds can enhance the adhesion, growth, and differentiation of somatic cells, thereby significantly improving the tissue regeneration process. However, the biological benefits of pure MPs composite scaffold are limited. Therefore, physical, chemical, enzyme modification and other methods are employed to expand its efficacy. Chemically, the structural properties of MPs scaffolds can be altered through modifications to functional groups or molecular weight reduction, thereby enhancing their biological activities. Physically, MPs hydrogels and sponges emulate the natural extracellular matrix, creating a more conducive environment for tissue repair. The porosity and high permeability of MPs membranes and nanomaterials expedite wound healing. This review explores the distinctive properties and applications of select MPs in tissue regeneration, highlighting their structural versatility and biological applicability. Additionally, we provide a brief overview of common modification strategies employed for MP scaffolds. In conclusion, MPs have significant potential and are expected to be a novel regenerative material for tissue engineering.

Fabrication, Characterization, and In Vitro Cytotoxicity Assessment of Tri-Layered Multifunctional Scaffold for Effective Chronic Wound Healing

Chronic wounds have been a global health risk that demands intensive exploration. A tri-layered biomaterial scaffold has been developed for skin wounds. The top layer of the scaffold is superhydrophobic, and the bottom layer is hydrophilic, both of which were electrospun using recycled expanded polystyrene (EPS) and monofilament fishing line (MFL), respectively. The intermediate layer of the scaffold comprised hydrogel by cross-linking chitosan (CS) with polyethylene glycol. The surface morphology, surface chemistry, thermal degradation, and wettability characteristics of each layer of the scaffold were examined. Also, the antibacterial activity and in vitro cytotoxicity study on the combined tri-layered scaffold were assessed against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Data revealed exceptional water repellency of the heat-treated electrospun top superhydrophobic layer (TSL) with a high-water contact angle (WCA) of 172.44°. A TSL with 15 wt% of micro-/nano-inclusions had the best thermal stability above 400 °C. The bottom hydrophilic layer (BHL) displayed a WCA of 9.91°. Therapeutically, the synergistic effect of the combined tri-layered scaffold significantly inhibited bacteria growth by 70.5% for E. coli and 68.6% for S. aureus. Furthermore, cell viability is enhanced when PEG is included as part of the intermediate CS hydrogel layer (ICHL) composition.

Cell electrospinning and its application in wound healing: principles, techniques and prospects

Currently, clinical strategies for the treatment of wounds are limited, especially in terms of achieving rapid wound healing. In recent years, based on the technique of electrospinning (ES), cell electrospinning (C-ES) has been developed to better repair related tissues or organs (such as skin, fat and muscle) by encapsulating living cells in a microfiber or nanofiber environment and constructing 3D living fiber scaffolds. Therefore, C-ES has promising prospects for promoting wound healing. In this article, C-ES technology and its advantages, the differences between C-ES and traditional ES, the parameters suitable for maintaining cytoactivity, and material selection and design issues are summarized. In addition, we review the application of C-ES in the fields of biomaterials and cells. Finally, the limitations and improved methods of C-ES are discussed. In conclusion, the potential advantages, limitations and prospects of C-ES application in wound healing are presented.

Chitosan and its derivatives in 3D/4D (bio) printing for tissue engineering and drug delivery applications

Tissue engineering research has undergone to a revolutionary improvement, thanks to technological advancements, such as the introduction of bioprinting technologies. The ability to develop suitable customized biomaterial inks/bioinks, with excellent printability and ability to promote cell proliferation and function, has a deep impact on such improvements. In this context, printing inks based on chitosan and its derivatives have been instrumental. Thus, the current review aims at providing a comprehensive overview on chitosan-based materials as suitable inks for 3D/4D (bio)printing and their applicability in creating advanced drug delivery platforms and tissue engineered constructs. Furthermore, relevant strategies to improve the mechanical and biological performances of this biomaterial are also highlighted.

Cytocompatible and osteoinductive cotton cellulose nanofiber/chitosan nanobiocomposite scaffold for bone tissue engineering

Natural polymeric nanobiocomposites hold promise in repairing damaged bone tissue in tissue engineering. These materials create an extracellular matrix (ECM)-like microenvironment that induces stem cell differentiation. In this study, we investigated a new cytocompatible nanobiocomposite made from cotton cellulose nanofibers (CNFs) combined with chitosan polymer to induce osteogenic stem cell differentiation. First, we characterized the chemical composition, nanotopography, swelling properties, and mechanical properties of the cotton CNF/chitosan nanobiocomposite scaffold. Then, we examined the biological characteristics of the nanocomposites to evaluate their cytocompatibility and osteogenic differentiation potential using human mesenchymal stem cells derived from exfoliated deciduous teeth. The results showed that the nanobiocomposite exhibited favorable cytocompatibility and promoted osteogenic differentiation of cells without the need for chemical inducers, as demonstrated by the increase in alkaline phosphatase activity and ECM mineralization. Therefore, the cotton CNF/chitosan nanobiocomposite scaffold holds great promise for bone tissue engineering applications.

Antimicrobial and Biodegradable 3D Printed Scaffolds for Orthopedic Infections

In bone tissue engineering, the performance of scaffolds underpins the success of the healing of bone. Microbial infection is the most challenging issue for orthopedists. The application of scaffolds for healing bone defects is prone to microbial infection. To address this challenge, scaffolds with a desirable shape and significant mechanical, physical, and biological characteristics are crucial. 3D printing of antibacterial scaffolds with suitable mechanical strength and excellent biocompatibility is an appealing strategy to surmount issues of microbial infection. The spectacular progress in developing antimicrobial scaffolds, along with beneficial mechanical and biological properties, has sparked further research for possible clinical applications. Herein, the significance of antibacterial scaffolds designed by 3D, 4D, and 5D printing technologies for bone tissue engineering is critically investigated. Materials such as antibiotics, polymers, peptides, graphene, metals/ceramics/glass, and antibacterial coatings are used to impart the antimicrobial features for the 3D scaffolds. Polymeric or metallic biodegradable and antibacterial 3D-printed scaffolds in orthopedics disclose exceptional mechanical and degradation behavior, biocompatibility, osteogenesis, and long-term antibacterial efficiency. The commercialization aspect of antibacterial 3D-printed scaffolds and technical challenges are also discussed briefly. Finally, the discussion on the unmet demands and prevailing challenges for ideal scaffold materials for fighting against bone infections is included along with a highlight of emerging strategies in this field.

Polyvinyl Alcohol Nanofibers Blends as Drug Delivery System in Tissue Regeneration

Nanofibers have shown promising clinical results in the process of tissue regeneration since they provide a similar structure to the extracellular matrix of different tissues, high surface-to-volume ratio and porosity, flexibility, and gas permeation, offering topographical features that stimulate cell adhesion and proliferation. Electrospinning is one of the most used techniques for manufacturing nanomaterials due to its simplicity and low cost. In this review, we highlight the use of nanofibers produced with polyvinyl alcohol and polymeric associations (PVA/blends) as a matrix for release capable of modifying the pharmacokinetic profile of different active ingredients in the regeneration of connective, epithelial, muscular, and nervous tissues. Articles were selected by three independent reviewers by analyzing the databases, such as Web of Science, PubMed, Science Direct, and Google Scholar (last 10 years). Descriptors used were "nanofibers", "poly (vinyl alcohol)", "muscle tissue", "connective tissue", "epithelial tissue", and "neural tissue engineering". The guiding question was: How do different compositions of polyvinyl alcohol polymeric nanofibers modify the pharmacokinetics of active ingredients in different tissue regeneration processes? The results demonstrated the versatility of the production of PVA nanofibers by solution blow technique with different actives (lipo/hydrophilic) and with pore sizes varying between 60 and 450 nm depending on the polymers used in the mixture, which influences the drug release that can be controlled for hours or days. The tissue regeneration showed better cellular organization and greater cell proliferation compared to the treatment with the control group, regardless of the tissue analyzed. We highlight that, among all blends, the combinations PVA/PCL and PVA/CS showed good compatibility and slow degradation, indicating their use in prolonged times of biodegradation, thus benefiting tissue regeneration in bone and cartilage connective tissues, acting as a physical barrier that results in guided regeneration, and preventing the invasion of cells from other tissues with increased proliferation rate.

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.

Electrospun bio-nano hybrid scaffold from collagen, Nigella sativa, and chitosan for skin tissue engineering application

The new sophisticated tissue engineering focused on producing nanocomposite with different morphologies for rapid tissue regeneration. In this case, utilizing nanotechnology with the incorporation of bio-based materials have achieved the interest of researchers. This research aims at developing hybrid bio-nano scaffold with collagen (Col), Nigella sativa ( Ns), and chitosan (Cs) by a bi-layered green electrospinning on polyvinyl chloride (PVA) layer in a different ratio for tissue regeneration. Field emission electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FTIR), moisture management properties, tensile properties, antibacterial activity, and wound healing assessment of the fabricated hybrid bio-nano scaffolds were employed to investigate the different properties of hybrid bio-nano scaffolds. The results exhibit that the sample with Col (50%) and Ns (25%), Cs (25%) has good fiber formation with a mean diameter of 381 ± 22 nm. This bio-nano scaffold has a porosity of 78 ± 6.9% and a fast absorbing-slow drying nature for providing a moist environment. The antibacterial zones of inhibition (ZOI) against Staphylococcus aureus and Escherichia coli were 10 ± 1.3 and 8 ± 0.9 mm respectively, and appeared to be adequate to inhibit bacterial action. The wound healing assessment states that 84 ± 3.8% of wound closure occurs in just 10 days, which is quicker (1.5 times) than the duration of a commercial bandage. All of the findings suggest that the bio-nano scaffold could be useful for skin tissue engineering.

Design, development and characterisation of an optimised scaffold to enhance cell proliferation for tissue repair

Scaffolds are implanted to spur the regeneration of damaged tissues. The inappropriate construction of scaffolds laden with cells is not efficient. The optimisation of the scaffolds' constituents is essential for tissue repair. In this study, a scaffold embedded with Raloxifene drug was optimised via Response Surface Methodology (RSM), targeting controlled cell proliferation. The independent variables for RSM (fibronectin, collagen I, glutaraldehyde, and Raloxifene) were screened in Swiss target prediction software (probability ≥99%) to optimise dependent variables (porosity, cell viability, degradation, and swelling) by ANOVA and characterised with FTIR, SEM and contact angle measurement. The scaffold was tested for antimicrobial property, and proliferation and attachment of mouse mesenchymal stem cells. The ANOVA analysis with p value ≤ 0.0001 suggested the optimal concentration of biomaterials and drugs. The optimised scaffold displayed 80% porosity with pore size 33 ± 3 µm. We also observed significant cell attachment and proliferation (p value ≤ 0.05) in optimised scaffold. The scaffold may be further evaluated for its potential for tissue repair.

Gadolinium-doped whitlockite/chitosan composite scaffolds with osteogenic activity for bone defect treatment: In vitro and in vivo evaluations

Reducing the incidence of bone defects caused by trauma and other primary diseases is an urgent task in modern society. In the present study, we developed a gadolinium-doped whitlockite/chitosan (Gd-WH/CS) scaffold and assessed its biocompatibility, osteoinductivity, and bone regeneration capacity for the treatment of calvarial defect in a Sprague-Dawley (SD) rat model. The Gd-WH/CS scaffolds possessed a macroporous structure, with a pore size ranging 200-300 μm, which facilitated the growth of bone precursor cells and tissues into scaffold. Results of cytological and histological biosafety experiments showed that both WH/CS and Gd-WH/CS scaffolds were non-cytotoxic to human adipose-derived stromal cells (hADSCs) and bone tissue, which demonstrated the excellent biocompatibility of Gd-WH/CS scaffolds. Results of western blotting and real-time PCR analysis provided a possible mechanism that Gd³⁺ ions in the Gd-WH/CS scaffolds promoted the osteogenic differentiation of hADSCs through the GSK3β/β-catenin signaling pathway and significantly upregulated the expression of osteogenic related genes (OCN, OSX and COL1A1). Finally, in animal experiments, SD rat cranial defects were effectively treated and repaired with Gd-WH/CS scaffolds due to its appropriate degradation rate and excellent osteogenic activity. This study suggests the potential utility of the Gd-WH/CS composite scaffolds in treating bone defect disease.

Biomaterial-assisted tumor therapy: A brief review of hydroxyapatite nanoparticles and its composites used in bone tumors therapy

Malignant bone tumors can inflict significant damage to affected bones, leaving patients to contend with issues like residual tumor cells, bone defects, and bacterial infections post-surgery. However, hydroxyapatite nanoparticles (nHAp), the principal inorganic constituent of natural bone, possess numerous advantages such as high biocompatibility, bone conduction ability, and a large surface area. Moreover, nHAp's nanoscale particle size enables it to impede the growth of various tumor cells via diverse pathways. This article presents a comprehensive review of relevant literature spanning the past 2 decades concerning nHAp and bone tumors. The primary goal is to explore the mechanisms responsible for nHAp's ability to hinder tumor initiation and progression, as well as to investigate the potential of integrating other drugs and components for bone tumor diagnosis and treatment. Lastly, the article discusses future prospects for the development of hydroxyapatite materials as a promising modality for tumor therapy.

Bioactive Nanocomposite Microsponges for Effective Reconstruction of Critical-Sized Calvarial Defects in Rat Model

Introduction

Micro-sized sponge particulates have attracted extensive attention because of their potential to overcome the intrinsic limitations of conventional monolithic scaffolds in tissue engineering. Bioactive nanocomposite microsponges are regarded as potential bone substitute materials for bone regeneration.

Methods

Based on a combination of microfluidic emulsion with further freezing and in situ thawing, chitosan (CS)-hydroxyapatite (HAP) microsponges were prepared and characterized in terms of their morphology and elemental distribution using a scanning electron microscope equipped with an X-ray detector. The swelling ratio, porosity, degradability, antibacterial activity, and bioactivity were detected and analyzed. The biological functions of the CS-HAP microsponges were examined to assess the adhesion, proliferation, and differentiation of in vitro co-cultured rat bone marrow mesenchymal stem cells (rBMSCs). Furthermore, the CS-HAP microsponges were used as cell-free scaffolds and implanted into calvarial defects in a rat model to evaluate the in vivo osteogenesis.

Results

The CS-HAP microsponges have a porous structure with high porosity (~76%), good swelling capacity (~1900%), and shape-memory properties. The results of in vitro experiments show that the CS-HAP microsponges achieve good bioactivity and promote osteogenic differentiation of rBMSCs. Furthermore, the CS-HAP microsponges significantly promote bone regeneration in rat calvarial defects.

Conclusion

The bioactive CS-HAP microsponges have the potential to be used as bone substitute materials for bone tissue engineering.

Generation of dorsoventral human spinal cord organoids via functionalizing composite scaffold for drug testing

The spinal cord possesses highly complex, finely organized cytoarchitecture guided by two dorsoventral morphogenic organizing centers. Thus, generation of human spinal cord tissue in vitro is challenging. Here, we demonstrated a novel method for generation of human dorsoventral spinal cord organoids using composite scaffolds. Specifically, the spinal cord ventralizing signaling Shh agonist (SAG) was loaded into a porous chitosan microsphere (PCSM), then thermosensitive Matrigel was coated on the surface to form composite microspheres with functional sustained-release SAG, termed as PCSM-Matrigel@SAG. Using PCSM-Matrigel@SAG as the core to induce 3D engineering of human spinal cord organoids from human pluripotent stem cells (ehSC-organoids), we found ehSC-organoids could form dorsoventral spinal cord-like cytoarchitecture with major domain-specific progenitors and neurons. Besides, these ehSC-organoids also showed functional calcium activity. In summary, these ehSC-organoids are of great significance for modeling spinal cord development, drug screening as 3D models for motor neuron diseases, and spinal cord injury repair.

Chitosan and its application in dental implantology

OBJECTIVE

The aim of this review was to evaluate the properties of chitosan for an application in dental implantology.

METHODS

Electronic Databases: PubMed, Google Scholar, Scopus, were used to recherche the articles published from 2010 to 2021. The keywords used were: chitosan, biocompatible, antibacterial, osseointegration, implant, bioactive. After a carefully selection according to the above keywords 46 articles met the condition to be studied RESULTS: Chitosan is a biopolymer, that can be easy produced. Its antibacterial, anti-inflammatory, anti-fugal, hemostatic, analgesic, mucoadhesive, osseointegrative properties and its excellent film-forming ability make chitosan a material with a future in dental implantology and in other areas of dental applications. Titan implants coated with chitosan showed better bioactive properties than uncoated implants. The treatment of the implant surface played an important role on the stability of implants. The activity of osteoblasts increased when the surface was laser-treated followed by coating with chitosan. The subsequent coating with apatite improved the bioactivity of chitosan.

CONCLUSION

Chitosan is a promising biocompatible and bioactive material in dental implantology. Its antibacterial properties can be enhanced by modification of its structure. Its bioactive properties can be improved when mixing with hydroxy apatite.

Marine polysaccharide laminarin embedded ZnO nanoparticles and their based chitosan capped ZnO nanocomposites: Synthesis, characterization and in vitro and in vivo toxicity assessment

In the current scenario where more and more products containing nanomaterials are on the technological or pharmaceutical market, it is crucial to have a thorough knowledge of their toxicity before proposing possible applications. A proper analysis of the toxicity of the nanoproducts should include both in vitro and in vivo biological approaches and should consider that the synthesis and purification methods of nanomaterials may affect such toxicity. In the current work, the green synthesis of laminarin embedded ZnO nanoparticles (Lm-ZnO NPs) and their based chitosan capped ZnO nanocomposites (Ch-Lm-ZnO NCmps) is described for the first time. Furthermore, the evaluation of their in vitro cytotoxicity, phytotoxicity, and in vivo (Zebrafish embryo) toxicity was described. First, the green synthesized Lm-ZnO NPs and Ch-Lm-ZnO NCmps were fully physicochemically characterized. Lm-ZnO NPs were greatly agglomerated and had a spindle morphology ranging from 100 to 350 nm, while Ch-Lm-ZnO NCmps had irregular rod shape with flake-like structure clusters randomly aggregated with diverse sizes ranging from 20 to 250 nm. The in vitro cytotoxicity assessment of the green synthesized Lm-ZnO NPs and Ch-Lm-ZnO NCmps was carried out in normal human dermal fibroblasts (HDF) cells and human colon cancer (HT-29) cells by MTT assay. Lm-ZnO NPs and Ch-Lm-ZnO NCmps (0.1-500 μg/mL), significantly inhibited the viability of both cell lines, revealing dose-dependent cytotoxicity. Besides, the Lm-ZnO NPs and Ch-Lm-ZnO NCmps significantly affected seed germination and roots and shoots length of mung (Vigna radiata). Moreover, the zebrafish embryo toxicity of Lm-ZnO NPs and Ch-Lm-ZnO NCmps among the various concentrations used (0.1-500 μg/mL) caused deformities, increased mortality and decreased the survival rate of zebrafish embryo dose-dependently.

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.

Functionalization of Electrospun Nanofiber for Bone Tissue Engineering

Bone-tissue engineering is an alternative treatment for bone defects with great potential in which scaffold is a critical factor to determine the effect of bone regeneration. Electrospun nanofibers are widely used as scaffolds in the biomedical field for their similarity with the structure of the extracellular matrix (ECM). Their unique characteristics are: larger surface areas, porosity and processability; these make them ideal candidates for bone-tissue engineering. This review briefly introduces bone-tissue engineering and summarizes the materials and methods for electrospining. More importantly, how to functionalize electrospun nanofibers to make them more conducive for bone regeneration is highlighted. Finally, the existing deficiencies of functionalized electrospun nanofibers for promoting osteogenesis are proposed. Such a summary can lay the foundation for the clinical practice of functionalized electrospun nanofibers.

Application Progress of Modified Chitosan and Its Composite Biomaterials for Bone Tissue Engineering

In recent years, bone tissue engineering (BTE), as a multidisciplinary field, has shown considerable promise in replacing traditional treatment modalities (i.e., autografts, allografts, and xenografts). Since bone is such a complex and dynamic structure, the construction of bone tissue composite materials has become an attractive strategy to guide bone growth and regeneration. Chitosan and its derivatives have been promising vehicles for BTE owing to their unique physical and chemical properties. With intrinsic physicochemical characteristics and closeness to the extracellular matrix of bones, chitosan-based composite scaffolds have been proved to be a promising candidate for providing successful bone regeneration and defect repair capacity. Advances in chitosan-based scaffolds for BTE have produced efficient and efficacious bio-properties via material structural design and different modifications. Efforts have been put into the modification of chitosan to overcome its limitations, including insolubility in water, faster depolymerization in the body, and blood incompatibility. Herein, we discuss the various modification methods of chitosan that expand its fields of application, which would pave the way for future applied research in biomedical innovation and regenerative medicine.

Effect of glutaraldehyde and calcium chloride as different crosslinking agents on the characteristics of chitosan/cellulose nanocrystals scaffold

The effect of glutaraldehyde and calcium cations as covalent and ionic crosslinkers was investigated on the main characteristics of scaffolds based on chitosan and cellulose nanocrystals. Therefore, four different scaffolds based on chitosan/cellulose nanocrystals with different crosslinking methods were fabricated using the freeze-drying method for potential use in bone tissue engineering. The structural and chemical features of prepared scaffolds were studied by the FTIR technique. FESEM images revealed that all scaffold samples are porous three-dimensional networks in which the pores are connected. TGA analysis showed that the thermal stability of scaffolds based on chitosan/cellulose nanocrystals has not been changed significantly by using different crosslinking methods. The chitosan/cellulose nanocrystals scaffold crosslinked by glutaraldehyde represented the highest compressive strength and the uncrosslinked scaffold showed the highest swelling ratio in comparison to the other scaffolds. The fastest degradation rate belonged to the scaffold crosslinked by calcium cations. FESEM images and EDX analysis confirmed that fabricated scaffolds have good biomineralization ability. The cell viability and cell attachment results indicated that all four scaffolds support cell proliferation and cell adhesion. However, the viability of NIH3T3 fibroblast cells in the presence of glutaraldehyde-containing scaffolds was lower than that of other scaffolds.

Effect of chitosan-based gel dressing on wound infection, synechia, and granulations after endoscopic sinus surgery of nasal polyps: A meta-analysis

A meta-analysis was performed to evaluate the effect of chitosan-based gel dressing on wound infection, synechia, and granulations after endoscopic sinus surgery of nasal polyps. A systematic literature search until March 2022 incorporated 386 subjects after endoscopic sinus surgery of nasal polyps at the beginning of the study; 187 were using chitosan-based gel dressing, and 199 were control. Statistical tools like the dichotomous method were used within a random or fixed-influence model to establish the odds ratio (OR) with 95% confidence intervals (CIs) to evaluate the influence of chitosan-based gel dressing on wound infection, synechia, and granulations after endoscopic sinus surgery of nasal polyps. Chitosan-based gel dressing had significantly lower wound infection (OR, 0.48; 95% CI, 0.25-0.92, P = 0.03), and synechia (OR, 0.25; 95% CI, 0.13-0.50, P < 0.001) compared with control in subjects with endoscopic sinus surgery of nasal polyps. However, no significant difference was found in granulations between chitosan-based gel dressing and control in subjects with endoscopic sinus surgery of nasal polyps. Chitosan-based gel dressing had significantly lower wound infection, synechia compared with control in subjects with endoscopic sinus surgery of nasal polyps, and no significant difference in granulations. Further studies are required to validate these findings.

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.

Biopolymer-based nanocarriers for sustained release of agrochemicals: A review on materials and social science perspectives for a sustainable future of agri- and horticulture

Devastating plant diseases and soil depletion rationalize an extensive use of agrochemicals to secure the food production worldwide. The sustained release of fertilizers and pesticides in agriculture is a promising solution to the eco-toxicological impacts and it might reduce the amount and increase the effectiveness of agrochemicals administration in the field. This review article focusses on carriers with diameters below 1 μm, such as capsules, spheres, tubes and micelles that promote the sustained release of actives. Biopolymer nanocarriers represent a potentially environmentally friendly alternative due to their renewable origin and biodegradability, which prevents the formation of microplastics. The social aspects, economic potential, and success of commercialization of biopolymer based nanocarriers are influenced by the controversial nature of nanotechnology and depend on the use case. Nanotechnology's enormous innovative power is only able to unfold its potential to limit the effects of climate change and to counteract current environmental developments if the perceived risks are understood and mitigated.

Biogenic Synthesis and Characterization of Chitosan-CuO Nanocomposite and Evaluation of Antibacterial Activity against Gram-Positive and -Negative Bacteria

Chitosan-copper oxide (CHT-CuO) nanocomposite was synthesized using olive leaf extract (OLE) as reducing agent and CuSO4⋅5H2O as precursor. CHT-CuO nanocomposite was prepared using an in situ method in which OLE was added to a solution of chitosan and CuSO4⋅5H2O mixture in the ratio of 1:5 (v/v) and heated at a temperature of 90 °C. The obtained CHT-CuO nanocomposite was characterized using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectrophotometry, energy-dispersive X-ray spectroscopy (EDAX), Fourier transform infrared spectroscopy (FTIR), and high-resolution transmission electron microscopy (TEM). TEM results indicated that CHT-CuO nanocomposite are spherical in shape with size ranging from 3.5 to 6.0 nm. Antibacterial activity of the synthesized nanocomposites was evaluated against Gram-positive (Bacillus cereus, Staphyloccous haemolytica and Micrococcus Luteus) and Gram-negative (Escherichia coli, Pseudomonas citronellolis, Pseudomonas aeruginosa, kliebisella sp., Bradyrhizobium japonicum and Ralstonia pickettii) species by cup platting or disc diffusion method. Overall, against all tested bacterial strains, the diameters of the inhibition zone of the three nanocomposites fell between 6 and 24 mm, and the order of the antimicrobial activity was as follows: CuO-1.0 > CuO-0.5 > CuO-2.0. The reference antibiotic amoxicillin and ciprofloxacin showed greater activity based on the diameter of zones of inhibition (between 15−32 mm) except for S. heamolytica and P. citronellolis bacteria strains. The nanocomposites MIC/MBC were between 0.1 and 0.01% against all tested bacteria, except S. heamolityca (>0.1%). Based on MIC/MBC values, CuO-0.5 and CuO-1.0 were more active than CuO-2.0, in line with the observations from the disc diffusion experiment. The findings indicate that these nanocomposites are efficacious against bacteria; however, Gram-positive bacteria were less susceptible. The synthesized CHT-CuO nanocomposite shows promising antimicrobial activities and could be utilized as an antibacterial agent in packaging and medical applications.

Review on synthesis, properties and multifarious therapeutic applications of nanostructured zirconia in dentistry

Amongst dental ceramics, nano zirconia (ZrNp) has shown exceptional developments in the field of dentistry in recent years. Zirconia is an oxide that possess superior optical, mechanical, and biological properties. As a novel nanoparticle, it has been widely used in various fields of dentistry due to its improved mechanical properties, biocompatibility, and stable structure. Provision of metal free solutions is one of the prime requirements in dental materials. Many metal alloys used extensively possess unaesthetic colors and display chemical interactions in the oral cavity encouraging use of zirconia for dental use. Use of ZrNp based ceramics has increased due to its resistance to corrosion, superior color matching that enhances esthetics and improved strength compared to conventional biomaterials. This review discusses the recent scientific literature on the synthesis, properties and types, applications, and toxicity of ZrNp in the field of dentistry.

Polydopamine treatment of chitosan nanofibers for the conception of osteoinductive scaffolds for bone reconstruction

We report the influence of treatment time of electrospun chitosan nanofibers (CHT NFs) in dopamine hydrochloride bath (2 mg.mL^-1 in 10 mM Tris buffer, pH 8.5) on the extent of the polydopamine (pDA) coating on NFs surface. The reaction was characterized by FTIR and SEM analysis and the cytocompatibility of the scaffolds toward MT3C3-E1 cells was assessed. Biomimetic deposition of hydroxyapatite (HA) in 1.5xSBF batch was investigated by SEM-EDS and XRD. Samples treated in dopamine bath during 2 h promoted the structural stability of NFs in PBS, provided optimal cytocompatibility and induced the in vitro biomineralization from 6 days in 1.5xSBF. The XRD and SEM-EDS investigations confirmed formation of spherical-shaped particles composed of apatitic phase. Finally, this study shows that these NFs-pDA scaffolds prepared in the optimal experimental conditions defined here are promising candidates for application as osteoinductive scaffolds for bone regeneration applied to orthopedic and dental applications.

In Vivo Study of Nasal Bone Reconstruction with Collagen, Elastin and Chitosan Membranes in Abstainer and Alcoholic Rats

The aim of the present study was to evaluate the use of collagen, elastin, or chitosan biomaterial for bone reconstruction in rats submitted or not to experimental alcoholism. Wistar male rats were divided into eight groups, submitted to chronic alcohol ingestion (G5 to G8) or not (G1 to G4). Nasal bone defects were filled with clot in animals of G1 and G5 and with collagen, elastin, and chitosan grafts in G2/G6, G3/G7, and G4/G8, respectively. Six weeks after, all specimens underwent radiographic, tomographic, and microscopic evaluations. Bone mineral density was lower in the defect area in alcoholic animals compared to the abstainer animals. Bone neoformation was greater in the abstainer groups receiving the elastin membrane and in abstainer and alcoholic rats receiving the chitosan membrane (15.78 ± 1.19, 27.81 ± 0.91, 47.29 ± 0.97, 42.69 ± 1.52, 13.81 ± 1.60, 18.59 ± 1.37, 16.54 ± 0.89, and 37.06 ± 1.17 in G1 to G8, respectively). In conclusion, osteogenesis and bone density were more expressive after the application of the elastin matrix in abstainer animals and of the chitosan matrix in both abstainer and alcoholic animals. Chronic alcohol ingestion resulted in lower bone formation and greater formation of fibrous connective tissue.

Chitosan films and scaffolds for regenerative medicine applications: A review

Over the last years, chitosan has demonstrated unparalleled characteristics for regenerative medicine applications. Beside excellent antimicrobial and wound healing properties, this polysaccharide biopolymer offers favorable characteristics such as biocompatibility, biodegradability, and film and fiber-forming capabilities. Having plentiful active amine groups, chitosan can be also readily modified to provide auxiliary features for growing demands in regenerative medicine, which is constantly confronted with new problems, necessitating the creation of biocompatible, immunogenic and biodegradable film/scaffold composites. A new look at the chitosan composites structure/activity/application tradeoff is the primary focus of the current review, which can help researchers to detect the bottlenecks and overcome the shortcomings that arose from this intersection. In the current review, the most recent advances in chitosan films and scaffolds in terms of preparation techniques and modifying methods for improving their functional properties, in three major biomedical fields i.e., tissue engineering, wound healing, and drug delivery are surveyed and discussed.