Thermosensitive injectable hydrogel based on chitosan-polygalacturonic acid polyelectrolyte complexes for bone tissue engineering

Highly precise strategy of polygalacturonic acid microcarriers functionalized with zwitterions and specific peptides for MSC screening

Microcarriers for large-scale cell culture have a broader prospect in cell screening compared with the traditional high cost, low efficiency, and cell damaging methods. However, the equal biological affinity to cells has hindered its application. Therefore, based on the antifouling strategy of zwitterionic polymer, we developed a cell-specific microcarrier (CSMC) for shielding non-target cells and capturing mesenchymal stem cells (MSCs), which has characteristics of high biocompatibility, low background noise and high precision. Briefly, [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide and glycidyl methacrylate were grafted onto polygalacturonic acid, respectively. The former built a hydration layer through solvation to provide an excellent antifouling surface, while the latter provided active sites for the click reaction with sulfhydryl-modified cell-specific peptides, resulting in rapid immobilization of peptides. This method is applicable to the vast majority of polysaccharide materials. The accurate capture ratio of MSCs by CSMC in a mixed multicellular environment is >95 % and the proliferation rate of MSCs on microcarriers is satisfactory. In summary, this grafting strategy of bioactive components lays a foundation for the application of polysaccharide materials in the biomedical field, and the specific adhesive microcarriers also open up new ideas for the development of stem cell screening as well.

Progress in chitin/chitosan and their derivatives for biomedical applications: Where we stand

Chitin and its deacetylated form, chitosan, have demonstrated remarkable versatility in the realm of biomaterials. Their exceptional biocompatibility, antibacterial properties, pro- and anticoagulant characteristics, robust antioxidant capacity, and anti-inflammatory potential make them highly sought-after in various applications. This review delves into the mechanisms underlying chitin/chitosan's biological activity and provides a comprehensive overview of their derivatives in fields such as tissue engineering, hemostasis, wound healing, drug delivery, and hemoperfusion. However, despite the wealth of studies on chitin/chitosan, there exists a notable trend of homogeneity in research, which could hinder the comprehensive development of these biomaterials. This review, taking a clinician's perspective, identifies current research gaps and medical challenges yet to be addressed, aiming to pave the way for a more sustainable future in chitin/chitosan research and application.

Cartilage and bone injectable hydrogels: A review of injectability methods and treatment strategies for repair in tissue engineering

Cartilage and bone are crucial tissues causing disability in the elderly population, often requiring prolonged treatment and surgical intervention due to limited regenerative capacity. Injectable hydrogels that closely mimic the extracellular matrix (ECM) of native hard tissue have attracted attention due to their minimally invasive application and ability to conform to irregular defect sites. These hydrogels facilitate key biological processes such as cell migration, chondrogenesis in cartilage repair, osteoinduction, angiogenesis, osteoconduction, and mineralization in bone repair. This review analyzes in-vitro and in-vivo biomedical databases over the past decade to identify advancements in hydrogel formulations, crosslinking mechanisms, and biomaterial selection for cartilage and bone tissue engineering. The review emphasizes the effectiveness of injectable hydrogels as carriers for cells, growth factors, and drugs, offering additional therapeutic benefits. The relevance of these findings is discussed in the context of their potential to serve as a robust alternative to current surgical and non-surgical treatments. This review also examines the advantages of injectable hydrogels, such as ease of administration, reduced patient recovery time, and enhanced bioactivity, thereby emphasizing their potential in clinical applications for cartilage and bone regeneration with emphasis on addressing the shortcomings of current treatments.

Pharmaceutical chitosan hydrogels: A review on its design and applications

Chitosan (CS) has become a focal point of extensive research in the pharmaceutical industry due to its remarkable biodegradability, biocompatibility and sustainability. Chitosan hydrogels (CS HGs) are characterized by their viscoelasticity, flexibility and softness. The polar surfaces exhibit properties that mitigate interfacial tension between the hydrogel and body fluids. The inherent compatibility of CS HGs with body tissues and fluids positions them as outstanding polymers for delivering therapeutic proteins, peptides, DNA, siRNA, and vaccines. Designed to release drugs through mechanisms such as swelling-based diffusion, bioerosion, and responsiveness to stimuli, CS HGs offer a versatile platform for drug delivery. CS HGs play pivotal roles in serving purposes such as prolonging the duration of preprogrammed drug delivery, enabling stimuli-responsive smart delivery to target sites, protecting encapsulated drugs within the mesh network from adverse environments, and facilitating mucoadhesion and penetration through cell membranes. This review comprehensively outlines various novel preparation methods of CS HGs, delving into the parameters influencing drug delivery system design, providing a rationale for CS HG utilization in drug delivery, and presenting diverse applications across the pharmaceutical landscape. In synthesizing these facets, the review seeks to contribute to a nuanced understanding of the multifaceted role that CS HGs play in advancing drug delivery methodologies.

Injectable Biomimetic Gels for Biomedical Applications

Biomimetic gels are synthetic materials designed to mimic the properties and functions of natural biological systems, such as tissues and cellular environments. This manuscript explores the advancements and future directions of injectable biomimetic gels in biomedical applications and highlights the significant potential of hydrogels in wound healing, tissue regeneration, and controlled drug delivery due to their enhanced biocompatibility, multifunctionality, and mechanical properties. Despite these advancements, challenges such as mechanical resilience, controlled degradation rates, and scalable manufacturing remain. This manuscript discusses ongoing research to optimize these properties, develop cost-effective production techniques, and integrate emerging technologies like 3D bioprinting and nanotechnology. Addressing these challenges through collaborative efforts is essential for unlocking the full potential of injectable biomimetic gels in tissue engineering and regenerative medicine.

The Method of Direct and Reverse Phase Portraits as a Tool for Systematizing the Results of Studies of Phase Transitions in Solutions of Thermosensitive Polymers

It is shown that a more than significant amount of experimental data obtained in the field of studying systems based on thermosensitive hydrophilic polymers and reflected in the literature over the past decades makes the issue of their systematization and classification relevant. This, in turn, makes relevant the question of choosing the appropriate classification criteria. It is shown that the basic classification feature can be the number of phase transition stages, which can vary from one to four or more depending on the nature of the temperature-sensitive system. In this work, the method of inverse phase portraits is proposed for the first time. It was intended, among other things, to identify the number of phase transition stages. Moreover, the accuracy of this method significantly exceeds the accuracy of the previously used method of direct phase portraits since, for the first time, the operation of numerical differentiation is replaced by the operation of numerical integration. A specific example of the application of the proposed method for the analysis of a previously studied temperature-sensitive system is presented. It is shown that this method also allows for a quantitative comparison between the results obtained by the differential calorimetry method and the turbidimetry method. Issues related to increasing the resolution of the method of direct phase portraits are discussed.

A comprehensive review on recent progress in chitosan composite gels for biomedical uses

Chitosan (CS) composite gels have emerged as promising materials with diverse applications in biomedicine. This review provides a concise overview of recent advancements and key aspects in the development of CS composite gels. The unique properties of CS, such as biocompatibility, biodegradability, and antimicrobial activity, make it an attractive candidate for gel-based composites. Incorporating various additives, such as nanoparticles, polymers, and bioactive compounds, enhances the mechanical, thermal, and biological and other functional properties of CS gels. This review discusses the fabrication methods employed for CS composite gels, including blending and crosslinking, highlighting their influence on the final properties of the gels. Furthermore, the uses of CS composite gels in tissue engineering, wound healing, drug delivery, and 3D printing highlight their potential to overcome a number of the present issues with drug delivery. The biocompatibility, antimicrobial properties, electroactive, thermosensitive and pH responsive behavior and controlled release capabilities of these gels make them particularly suitable for biomedical applications. In conclusion, CS composite gels represent a versatile class of materials with significant potential for a wide range of applications. Further research and development efforts are necessary to optimize their properties and expand their utility in pharmaceutical and biomedical fields.

Chitosan-PNIPAM Thermogel Associated with Hydrogel Microspheres as a Smart Formulation for MSC Injection

Regenerative medicine based on cell therapy has emerged as a promising approach for the treatment of various medical conditions. However, the success of cell therapy heavily relies on the development of suitable injectable hydrogels that can encapsulate cells and provide a conducive environment for their survival, proliferation, and tissue regeneration. Herein, we address the medical need for cyto- and biocompatible injectable hydrogels by reporting on the synthesis of a hydrogel-forming thermosensitive copolymer. The copolymer was synthesized by grafting poly(N-isopropylacrylamide-co-carboxymethyl acrylate) (PNIPAM-COOH) onto chitosan through amide coupling. This chemical modification resulted in the formation of hydrogels that exhibit a sol-gel transition with an onset at approximately 27 °C, making them ideal for use in injectable applications. The hydrogels supported the survival and proliferation of cells for several days, which is critical for cell encapsulation. Furthermore, the study evaluates the addition of collagen/chitosan hybrid microspheres to support the adhesion of mesenchymal stem cells within the hydrogels. Altogether, these results demonstrate the potential of the PNIPAM-chitosan thermogel for cell encapsulation and its possible applications in regenerative medicine.

Polyelectrolytes for Environmental, Agricultural, and Medical Applications

In recent decades, polyelectrolytes (PELs) have attracted significant interest owing to a surge in research dedicated to the development of new technologies and applications at the biological level. Polyelectrolytes are macromolecules of which a substantial portion of the constituent units contains ionizable or ionic groups. These macromolecules demonstrate varied behaviors across different pH ranges, ionic strengths, and concentrations, making them fascinating subjects within the scientific community. The aim of this review is to present a comprehensive survey of the progress in the application studies of polyelectrolytes and their derivatives in various fields that are vital for the advancement, conservation, and technological progress of the planet, including agriculture, environmental science, and medicine. Through this bibliographic review, we seek to highlight the significance of these materials and their extensive range of applications in modern times.

Recent Applications of Chitosan and Its Derivatives in Antibacterial, Anticancer, Wound Healing, and Tissue Engineering Fields

Chitosan, a versatile biopolymer derived from chitin, has garnered significant attention in various biomedical applications due to its unique properties, such as biocompatibility, biodegradability, and mucoadhesiveness. This review provides an overview of the diverse applications of chitosan and its derivatives in the antibacterial, anticancer, wound healing, and tissue engineering fields. In antibacterial applications, chitosan exhibits potent antimicrobial properties by disrupting microbial membranes and DNA, making it a promising natural preservative and agent against bacterial infections. Its role in cancer therapy involves the development of chitosan-based nanocarriers for targeted drug delivery, enhancing therapeutic efficacy while minimising side effects. Chitosan also plays a crucial role in wound healing by promoting cell proliferation, angiogenesis, and regulating inflammatory responses. Additionally, chitosan serves as a multifunctional scaffold in tissue engineering, facilitating the regeneration of diverse tissues such as cartilage, bone, and neural tissue by promoting cell adhesion and proliferation. The extensive range of applications for chitosan in pharmaceutical and biomedical sciences is not only highlighted by the comprehensive scope of this review, but it also establishes it as a fundamental component for forthcoming research in biomedicine.

Synthesis and biological properties of novel glucose-based fluoro segmented macromolecular architectures

The emergence of novel well-defined biological macromolecular architectures containing fluorine moieties displaying superior functionalities can satisfactorily address many biomedical challenges. In this research, ABA- and AB-type glucose-based biological macromolecules were synthesized using acryl-2,3,4,6-tetra-O-acetyl-D-glucopyranoside with pentafluorophenyl (FPM), pentafluorobenzyl (FBM), phenyl (PM) and benzyl (BM) methacrylate-based macro-RAFT agents following RAFT polymerization. The macro-RAFT agents and the corresponding copolymers were characterized by 19F, 1H, and 13C NMR and FTIR spectroscopic techniques to understand the chemical structure, molecular weight by size-exclusion chromatography, thermal analysis by TGA and DSC. Thermal stability (Td5%) of the FPM and FBM fluoro-based polymers was observed in the range of 219-267 °C, while the non-fluoro PM and BM polymers exhibited in the range of 216-264 °C. Among the macro-RAFT agents, PFPM (107 °C, ΔH: 0.613 J/g) and PPM (103 °C, ΔH: 0.455 J/g) showed higher Tm values, while among the block copolymers, PFBM-b-PG (123 °C, ΔH: 0.412 J/g) and PG-b-PFPM-b-PG (126 °C, ΔH: 0.525 J/g) exhibited higher Tm values. PFBMT and PPM macro-RAFT agents, PPM-b-PG and PG-b-PPM-b-PG copolymer spin-coated films showed the highest hydrophobicity (120°) among the synthesized polymers. The block copolymers exhibited self-assembled segregation by using relatively hydrophobic segments as the core and hydrophilic moieties as the corona. Synthesized biological macromolecules exhibit maximum antibacterial activity towards S. aureus than E. coli bacteria. Fluorophenyl (PFPM) and non-fluorobenzyl-based (PBMT) macro-RAFT agents exhibit low IC50 values, suggesting high cytotoxicity. All the triblock copolymers exhibit lesser cytotoxicity than the di-block polymers.

Nanofibrous polyelectrolyte complex incorporated BSA-alginate composite bioink for 3D bioprinting of bone mimicking constructs

Although several bioinks have been developed for 3D bioprinting applications, the lack of optimal printability, mechanical properties, and adequate cell response has limited their practical applicability. Therefore, this work reports the development of a composite bioink consisting of bovine serum albumin (BSA), alginate, and self-assembled nanofibrous polyelectrolyte complex aggregates of gelatin and chitosan (PEC-GC). The nanofibrous PEC-GC aggregates were prepared and incorporated into the bioink in varying concentrations (0 % to 3 %). The bioink samples were bioprinted and crosslinked post-printing by calcium chloride. The average nanofiber diameter of PEC-GC was 62 ± 15 nm. It was demonstrated that PEC-GC improves the printability and cellular adhesion of the developed bioink and modulates the swelling ratio, degradation rate, and mechanical properties of the fabricated scaffold. The in vitro results revealed that the bioink with 2 % PEC-GC had the best post-printing cell viability of the encapsulated MG63 osteosarcoma cells and well oragnized stress fibers, indicating enhanced cell adhesion. The cell viability was >90 %, as observed from the MTT assay. The composite bioink also showed osteogenic potential, as confirmed by the estimation of alkaline phosphatase activity and collagen synthesis assay. This study successfully fabricated a high-shape fidelity bioink with potential in bone tissue engineering.

Cu-MSNs and ZnO nanoparticles incorporated poly(ethylene glycol) diacrylate/sodium alginate double network hydrogel for simultaneous enhancement of osteogenic differentiation

In this study, a double network (DN) hydrogel was synthesized using poly(ethylene glycol) diacrylate (PEGDA) and sodium alginate (SA), incorporating copper-doped mesoporous silica nanospheres (Cu-MSNs) and zinc oxide nanoparticles (ZnO NPs). The blending of PEGDA and SA (PS) facilitates the double network and improves the less porous microstructure of pure PEGDA hydrogel. Furthermore, the incorporation of ZnO NPs and Cu-MSNs into the hydrogel network (PS@ZnO/Cu-MSNs) improved the mechanical properties of the hydrogel (Compressive strength = ⁓153 kPa and Young's modulus = ⁓ 1.66 kPa) when compared to PS hydrogel alone (Compressive strength = ⁓ 103 kPa and Young's modulus = ⁓ 0.95 kPa). In addition, the PS@ZnO/Cu-MSNs composite hydrogel showed antibacterial activities against Staphylococcus aureus and Escherichia coli. Importantly, the PS@ZnO/Cu-MSNs hydrogel demonstrated excellent biocompatibility, enhanced MC3T3-E1 cell adhesion, proliferation, and significant early-stage osteoblastic differentiation, as evidenced by increased alkaline phosphatase (ALP), and improved calcium mineralization, as evidenced by increased alizarin red staining (ARS) activities. These findings point to the possible use of the PS@ZnO/Cu-MSNs composite hydrogel in bone tissue regeneration.

Injecting hope: chitosan hydrogels as bone regeneration innovators

Spontaneous bone regeneration encounters substantial restrictions in cases of bone defects, demanding external intervention to improve the repair and regeneration procedure. The field of bone tissue engineering (BTE), which embraces a range of disciplines, offers compelling replacements for conventional strategies like autografts, allografts, and xenografts. Among the diverse scaffolding materials utilized in BTE applications, hydrogels have demonstrated great promise as templates for the regeneration of bone owing to their resemblance to the innate extracellular matrix. In spite of the advancement of several biomaterials, chitosan (CS), a natural biopolymer, has garnered significant attention in recent years as a beneficial graft material for producing injectable hydrogels. Injectable hydrogels based on CS formulations provide numerous advantages, including their capacity to absorb and preserve a significant amount of water, their minimally invasive character, the existence of porous structures, and their capability to adapt accurately to irregular defects. Moreover, combining CS with other naturally derived or synthetic polymers and bioactive materials has displayed its effectiveness as a feasible substitute for traditional grafts. We aim to spotlight the composition, production, and physicochemical characteristics and practical utilization of CS-based injectable hydrogels, explicitly focusing on their potential implementations in bone regeneration. We consider this review a fundamental resource and a source of inspiration for future research attempts to pioneer the next era of tissue-engineering scaffold materials.

Artesunate-loaded thermosensitive chitosan hydrogel promotes osteogenesis of maxillary tooth extraction through regulating T lymphocytes in type 2 diabetic rats

BACKGROUND

Type 2 diabetes mellitus (T2DM) causes severe bone loss after tooth extraction as a hyperglycemic environment causes aberrant bone homeostasis. Artesunate (ART) is known to possess anti-inflammation and osteogenic properties. However, its osteogenesis property in alveolar bone remains unclear. This study aimed to explore the osteogenic and immunoregulatory effects of artesunate-loaded thermosensitive chitosan hydrogel (ART-loaded TCH) on maxilla tooth extraction in T2DM rats.

METHODS

T2DM rats were induced by a high-fat diet and streptozotocin. Different concentrations of ART-loaded TCH were applied in tooth extraction sockets. Bone loss and the expression of osteogenic regulatory factors (OPG, ALP, RANK) were evaluated. The immunoregulatory effects of ART-loaded TCH were observed through detecting the infiltration of T lymphocytes and their cytokines. The underlying mechanisms were explored.

RESULTS

Results showed that the 150 mg/ml ART-loaded TCH group significantly ameliorated maxilla bone height and bone mineral density when compared with the T2DM group (p < 0.05). It also improved the expression of OPG, ALP, and RANK. Although the alteration of CD4+ T, CD8+ T, and CD4+:CD8+ T ratio has no significant difference among groups, the release of Th1 and Th2 in the 150 mg/ml ART-loaded TCH group has been significantly regulated than in the T2DM group (p < 0.05). Besides, ART-loaded TCH treatment inhibited the expression of p38 MAPK and ERK1 in T2DM maxilla.

CONCLUSIONS

Therefore, the results indicated that 150 mg/ml ART-loaded TCH could be an effective method to prevent bone loss in T2DM tooth extraction rats by modulating the immunoregulation of Th1 and Th2 and the MAPK signaling pathway.

Self-assembled chitosan/gelatin nanofibrous aggregates incorporated thermosensitive nanocomposite bioink for bone tissue engineering

Chitosan-based thermosensitive bioink can be a potential option as bioinks for bone tissue engineering because of their excellent biocompatibility and crosslinker-free gelation at physiological temperature. However, their low mechanical strength, poor printability, and low post-printing cell viability are some of their limitations. In this work, self-assembled nanofibrous aggregates of chitosan and gelatin were prepared and incorporated in chitosan-based bioinks to enhance printability, mechanical properties, post-printing cell viability, and proliferation. Subsequently, the optimal concentration of nanohydroxyapatite was determined, and the potential of the nanocomposite bioink was evaluated. Physiochemical, mechanical, and in vitro characterizations were carried out for the developed nanocomposite bioink. The bioink had optimum printability at 10 % nanohydroxyapatite and cell viability >88 %. The composite bioink had a low water uptake capacity (2.5 %) and degraded within 3 weeks in the presence of lysozyme. Mechanical characterization revealed an elastic modulus of about 15.5 kPa. Rheological analysis indicated a higher storage modulus of the bioink samples at 37 °C. ALP activity of 36.8 units/ml after 14 days of scaffold culture in osteogenic media indicated high cellular activity. These results suggested that the incorporation of osteogenic nanohydroxyapatite and nanofibrous aggregates improved the overall osteogenic and physiochemical potential of the thermosensitive bioink.

Recent advances in biopolymer-based hydrogels and their potential biomedical applications

Hydrogels are three-dimensional networks of polymer chains containing large amounts of water in their structure. Hydrogels have received significant attention in biomedical applications owing to their attractive physicochemical properties, including flexibility, softness, biodegradability, and biocompatibility. Different natural and synthetic polymers have been intensely explored in developing hydrogels for the desired applications. Biopolymers-based hydrogels have advantages over synthetic polymers regarding improved cellular activity and weak immune response. These properties can be further improved by grafting with other polymers or adding nanomaterials, and they structurally mimic the living tissue environments, which opens their broad applicability. The hydrogels can be physically or chemically cross-linked depending on the structure. The use of different biopolymers-based hydrogels in biomedical applications has been reviewed and discussed earlier. However, no report is still available to comprehensively introduce the synthesis, advantages, disadvantages, and biomedical applications of biopolymers-based hydrogels from the material point of view. Herein, we systematically overview different synthesis methods of hydrogels and provide a holistic approach to biopolymers-based hydrogels for biomedical applications, especially in bone regeneration, wound healing, drug delivery, bioimaging, and therapy. The current challenges and prospects of biopolymers-based hydrogels are highlighted rationally, giving an insight into the progress of these hydrogels and their practical applications.

Temperature-Sensitive Nanocarbon Hydrogel for Photothermal Therapy of Tumors

Background

Intelligent hydrogels continue to encounter formidable obstacles in the field of cancer treatment. A wide variety of hydrogel materials have been designed for diverse purposes, but materials with satisfactory therapeutic effects are still urgently needed.

Methods

Here, we prepared an injectable hydrogel by means of physical crosslinking. Carbon nanoparticle suspension injection (CNSI), a sentinel lymph node imaging agent that has been widely used in the clinic, with sodium β-glycerophosphate (β-GP) were added to a temperature-sensitive chitosan (CS) hydrogel (CS/GP@CN) as an agent for photothermal therapy (PTT). After evaluating the rheological, morphological, and structural properties of the hydrogel, we used 4T1 mouse breast cancer cells and B16 melanoma cells to assess its in vitro properties. Then, we intratumorally injected the hydrogel into BALB/c tumor-bearing mice to assess the in vivo PTT effect, antitumor immune response and the number of lung metastases.

Results

Surprisingly, this nanocarbon hydrogel called CS/GP@CN hydrogel not only had good biocompatibility and a great PTT effect under 808nm laser irradiation but also facilitated the maturation of dendritic cells to stimulate the antitumor immune response and had an extraordinary antimetastatic effect in the lungs.

Discussion

Overall, this innovative temperature-sensitive nanocarbon hydrogel, which exists in a liquid state at room temperature and transforms to a gel at 37 °C, is an outstanding local delivery platform with tremendous PTT potential and broad clinical application prospects.

The effect of conductive aligned fibers in an injectable hydrogel on nerve tissue regeneration

Injectable hydrogels are a promising treatment option for nervous system injuries due to the difficulty to replace lost cells and nervous factors but research on injectable conductive hydrogels is limited and these scaffolds have poor electromechanical properties. This study developed a chitosan/beta-glycerophosphate/salt hydrogel and added conductive aligned nanofibers (polycaprolactone/gelatin/single-wall carbon nanotube (SWCNT)) for the first time and inspired by natural nerve tissue to improve their biochemical and biophysical properties. The results showed that the degradation rate of hydrogels is proportional to the regrowth of axons and these hydrogels' mechanical (hydrogels without nanofibers or SWCNTs and hydrogels containing these additions have the same Young's modulus as the brain and spinal cord or peripheral nerves, respectively) and electrical properties, and the interconnective structure of the scaffolds have the ability to support cells.

Synthesis, Characterization, Properties, and Biomedical Application of Chitosan-Based Hydrogels

The prospective applications of chitosan-based hydrogels (CBHs), a category of biocompatible and biodegradable materials, in biomedical disciplines such as tissue engineering, wound healing, drug delivery, and biosensing have garnered great interest. The synthesis and characterization processes used to create CBHs play a significant role in determining their characteristics and effectiveness. The qualities of CBHs might be greatly influenced by tailoring the manufacturing method to get certain traits, including porosity, swelling, mechanical strength, and bioactivity. Additionally, characterization methods aid in gaining access to the microstructures and properties of CBHs. Herein, this review provides a comprehensive assessment of the state-of-the-art with a focus on the affiliation between particular properties and domains in biomedicine. Moreover, this review highlights the beneficial properties and wide application of stimuli-responsive CBHs. The main obstacles and prospects for the future of CBH development for biomedical applications are also covered in this review.

Chitosan-Based Smart Biomaterials for Biomedical Applications: Progress and Perspectives

Over the past decade, smart and functional biomaterials have escalated as one of the most rapidly emerging fields in the life sciences because the performance of biomaterials could be improved by careful consideration of their interaction and response with the living systems. Thus, chitosan could play a crucial role in this frontier field because it possesses many beneficial properties, especially in the biomedical field such as excellent biodegradability, hemostatic properties, antibacterial activity, antioxidant properties, biocompatibility, and low toxicity. Furthermore, chitosan is a smart and versatile biopolymer due to its polycationic nature with reactive functional groups that allow the polymer to form many interesting structures or to be modified in various ways to suit the targeted applications. In this review, we provide an up-to-date development of the versatile structures of chitosan-based smart biomaterials such as nanoparticles, hydrogels, nanofibers, and films, as well as their application in the biomedical field. This review also highlights several strategies to enhance biomaterial performance for fast growing fields in biomedical applications such as drug delivery systems, bone scaffolds, wound healing, and dentistry.

Advanced injectable hydrogels for bone tissue regeneration

Diseases or defects of the skeleton are hazardous because of their specificity and intricacy. Bone tissue engineering has become an important area of research that offers promising new tools for making biomimetic hydrogels that can be used to treat bone diseases. New hydrogels with a distinctive 3D network structure, high water content, and functional capabilities are ranked among the most promising candidates for bone tissue engineering. This makes them helpful in treating cartilage injury, skull deformity, and arthritis. This review will briefly introduce the variety of biocompatible functional hydrogels used in cell culture and bone tissue regeneration. Many gel design concepts, such as crosslinking procedures, controlled release properties, and alternative bionic methodology, were stressed regarding injectable hydrogels to form bone tissue. Hydrogels manufactured from biocompatible materials are a promising option for minimally invasive surgery because of their adaptable physicochemical qualities, ability to fill irregularly shaped defect sites, and ability to grow hormones or release drugs in response to external stimuli. Also included in this overview is a quick rundown of the more practical designs employed in treating bone disorders. Essential details on injectable hydrogel scaffolds for bone tissue regeneration are described in this article.

Development of chitosan-polygalacturonic acid polyelectrolyte complex fibrous scaffolds using the hydrothermal treatment for bone tissue engineering

An ideal bone regeneration scaffold system needs to meet the high compressive properties of the bone. The stiffness of the scaffold extracellular matrix determines the cell's fate via cell adhesion migration and differentiation in-vitro and in-vivo. This study aims to investigate the effect of hydrothermal treatment on polyelectrolyte complex (PEC) fibrous biomaterials and its effect on scaffold morphology, cell viability, and function in-vitro. FTIR analysis revealed the ability of the thermal treatment to set the interaction of HAp with polymeric PEC fibers. FESEM analysis showed that with an increase in temperature, the interconnectivity and pore size increased (control-82.38 ± 12.92 μm; at 120°C-335.48 ± 85.10 μm). Mechanical tests showed that the scaffolds heated at 90°C showed the highest stiffness in both dry and wet states (dry state: 1.82 ± 0.07 MPa, wet state: 122 ± 1.78 kPa). Additionally, the hydrothermal treatment also improved the aqueous stability as well as swelling capacity. According to the experimental findings, hydrothermal treatment is a useful technique for crosslinker-free gelation with improved mechanical strength and nanofibrous structure. Furthermore, the cell adhesion, proliferation, and osteogenic differentiation of the MG63 cells on the hydrogel scaffolds in-vitro were evaluated by MTT assay, confocal imaging, alkaline phosphatase assay, and collagen estimation. The in-vitro study showed that scaffolds fabricated at 90°C promoted better MG63 cell attachment, proliferation, and differentiation. These results suggest the potential use of hydrothermal treated chitosan-polygalacturonic acid (PgA) fibrous scaffolds in bone tissue engineering.

Development of a flexible film made of polyvinyl alcohol with chitosan based thermosensitive hydrogel

Background/purpose

A challenge that arises with periodontal regeneration surgery has been associated with the future development of periodontal regeneration membrane to prevent gingiva and fibroblasts invade the wound and allow alveolar bone successfully regenerated.

Materials and methods

Chitosan (CS) has the advantages of non-toxicity, biodegradation, biocompatibility, and has been widely used in wound dressings. A flexible film was made using polyvinyl alcohol (PVA) blending CS based thermosensitive hydrogel.

Results

The proposed 2% PVA/CS hydrogel has the highest swelling ratio about 720% after 60 min incubation and keeps its area after 10 min incubation for surgery suture. The elastic modulus of 0%, 1%, 2%, and 4% PVA/CS hydrogel were 7.75 ± 1.96, 0.91 ± 0.16, 0.75 ± 0.21, and 0.37 ± 0.06 MPa, respectively. The maximum strain of 2% PVA/CS hydrogel was 101.00 ± 28.03 (%). After 8 weeks biodegradation, the remain weight of 2% PVA/CS hydrogel was 71.36 ± 0.79 (%).

Conclusion

In vitro cytotoxicity tests were performed and demonstrated PVA/CS hydrogel significantly improving cell proliferation. This study realized a promising flexible film for periodontal regeneration membrane that can prevent the rapid growth of fibroblasts to invade the wound and be used for periodontal regeneration surgery.

Biomaterials Based on Chitosan and Its Derivatives and Their Potential in Tissue Engineering and Other Biomedical Applications-A Review

In the times of dynamically developing regenerative medicine, more and more attention is focused on the use of natural polymers. This is due to their high biocompatibility and biodegradability without the production of toxic compounds, which means that they do not hurt humans and the natural environment. Chitosan and its derivatives are polymers made most often from the shells of crustaceans and are biodegradable and biocompatible. Some of them have antibacterial or metal-chelating properties. This review article presents the development of biomaterials based on chitosan and its derivatives used in regenerative medicine, such as a dressing or graft of soft tissues or bones. Various examples of preparations based on chitosan and its derivatives in the form of gels, films, and 3D structures and crosslinking products with another polymer are discussed herein. This article summarizes the latest advances in medicine with the use of biomaterials based on chitosan and its derivatives and provides perspectives on future research activities.