In situ forming alginate/gelatin hydrogel scaffold through Schiff base reaction embedded with curcumin-loaded chitosan microspheres for bone tissue regeneration

Fabrication and characterization of in situ gelling oxidized carboxymethyl cellulose/gelatin nanofibers for wound healing applications

Although tissue engineering science has made great progress, wound healing has remained a significant clinical challenge, especially in cases of severe injuries requiring advanced treatment strategies. This study aimed to develop patient-friendly in situ gelling nanofibers composed of oxidized carboxymethyl cellulose (OCMC) and gelatin for wound healing applications. A two-axial electrospinning technique was employed to fabricate OCMC/PVA-Gelatin hybrid nanofibers. Because of the nanofibers' high surface area, the resulting scaffold can quickly absorb wound exudates, resulting in a cross-linked hydrogel via the Schiff-base reaction between OCMC and gelatin. The nanofibers were thoroughly characterized using SEM, FTIR, XRD, and TGA, confirming their successful fabrication and structural integrity. Notably, the nanofibers demonstrated full degradation within 21 days, aligning with the requirements for skin tissue regeneration. Antibacterial assays revealed 99.9 % efficacy against Pseudomonas aeruginosa and Methicillin-Resistant Staphylococcus aureus (MRSA). The electrospun OCMC/PVA and OCMC/PVA-Gel samples exhibited 91 ± 10 % and 92 ± 7 % cell viability after 7 days of L929 fibroblast cell culture, confirming their excellent biocompatibility. These findings highlight the potential of the developed nanofibers as antimicrobial and biocompatible wound dressings with an appropriate degradation profile, presenting a practical and effective alternative to conventional hydrogel systems for advanced wound healing applications.

Hydrogel composite scaffold repairs knee cartilage defects: a systematic review

Currently, the incidence of cartilage defects in knee joints owing to different causes is increasing every year, and surgery is the most common treatment strategy. In general, tissue engineering materials that mimic the structural, mechanical, and biological properties of natural bone have been widely used, with hydrogels being particularly prominent due to their good biocompatibility as well as adjustable mechanical properties. However, the inherent limitations of monolithic materials in mimicking the complex zonal organization of articular cartilage have driven significant progress in composite scaffold engineering. Herein, we briefly outline the structure of the knee joint and several common surgical approaches for knee cartilage defects. We also discuss the physical properties, functions, and preparation methods of common hydrogel composite scaffolds according to their different types. Finally, we review their application in knee cartilage defects and summarize and discuss their future prospects.

A Narrative Review of Bioactive Hydrogel Microspheres: Ingredients, Modifications, Fabrications, Biological Functions, and Applications

Hydrogel microspheres are important in regenerative medicine and tissue engineering, acting as cargos of cells, drugs, growth factors, bio-inks for 3D printing, and medical devices. The antimicrobial and anti-inflammatory characteristics of hydrogel microspheres are good for treating injured tissues. However, the biological properties of hydrogel microspheres should be modified for optimal treatment of various body parts with different physiological and biochemical environments. In addition, specific preparation methods are required to produce customized hydrogel microspheres with different shapes and sizes for various clinical applications. Herein, the advances in hydrogel microspheres for biomedical applications are reviewed. Synthesis methods for hydrogel precursor solutions, manufacturing methods, and strategies for enhancing the biological functions of these hydrogel microspheres are described. The involvement of bioactive hydrogel microspheres in tissue repair is also discussed. This review anticipates fostering more insights into the design, production, and application of hydrogel microspheres in biomedicine.

Progress in injectable hydrogels for hard tissue regeneration in the last decade

Bone disorders have increased with increasing the human lifespan, and despite the tissue's ability to self-regeneration, in many congenital problems and hard fractures, bone grafting such as autograft, allograft, and biomaterials implantation through surgery is traditionally used. Because of the adverse effects of these methods, the emergence of injectable hydrogels without the need for surgery and causing more pain for the patient is stunning to develop a new pattern for hard tissue engineering. These materials are formed with various natural and synthetic polymers with a crosslinked network through various chemical methods such as click chemistry, Michael enhancement, Schiff's base and enzymatic reaction and physical interactions with high water absorption which can mimic the environment of cells. The purpose of this research is to review the capabilities of this class of materials in hard tissue regeneration in the last decade through adaptable physical and chemical properties, the ability to fill defect sites with an irregular shape, and the ability to grow hormones or release drugs, in response to external stimuli.

Ulva Seaweed-Derived Ulvan: A Promising Marine Polysaccharide as a Sustainable Resource for Biomaterial Design

Green seaweed is currently underused compared with other major seaweed types. Many scientists have reported applications of the green seaweed Ulva in various fields in recent years, which makes it a candidate for biomass production in industrial biorefineries. Ulva contains a unique polysaccharide called ulvan, which is being considered for medicinal and pharmacological applications. Ulvan is a sulfated polysaccharide including rhamnose and glucuronic acid residues, which has a range of bioactivities, including immunomodulatory, antimicrobial, and anticoagulant properties. The biocompatibility of ulvan makes it a versatile candidate for biomaterial design. This review presents an in-depth analysis of the potential applications of ulvan, starting with extraction methods and structural/biological characterization and moving on to biomaterial design. We also highlight the advantages of ulvan over traditional seaweed polysaccharides such as agar, carrageenan, and alginate.

Chitosan nanoparticles of imatinib mesylate coated with TPGS for the treatment of colon cancer: In-vivo & in-vitro studies

The study aimed to develop and evaluate chitosan-based nanoparticles coated with TPGS for the targeted delivery of imatinib mesylate to colon cancer cells. Particle size and zeta potential analysis were within the acceptable range for targeting colon cancer. CS-IMT-TPGS-NPs had a significant positive zeta potential of 30.4 mV, suggesting improved cellular intake. FE-SEM and TEM demonstrated that the nanoparticles appeared spherical, smooth, and did not aggregate, with a visible TPGS coating. XRD confirmed that crystalline imatinib transitioned to an amorphous state during nano formulation. In-vitro tests on HCT-116 cells demonstrated that CS-IMT-TPGS-NPs outperformed free IMT regarding cytotoxicity, apoptosis induction, cellular uptake, and cell migration inhibition. Additionally, the nanoparticles were examined in vitro using mitochondrial membrane potential, DNA fragmentation, GAPDH relative gene expression, ROS estimation, and cell cycle analysis. The effect of therapy on expected colon-associated bacterial strains was also investigated. The biocompatibility of nanoparticles was assessed by hemolysis and platelet aggregation experiments. The anti-inflammatory impact was determined using the HET-CAM test. Non-Fickian diffusion at pH 5.5 resulted in sustained in-vitro drug release, with no initial burst. In-vivo investigations using albino Wistar rats suggest pharmacokinetic properties for produced nanoparticles, whereas histopathological examinations assess acute toxicity.

FRESH 3D printing of zoledronic acid-loaded chitosan/alginate/hydroxyapatite composite thermosensitive hydrogel for promoting bone regeneration

The aim of this study was to develop a composite thermosensitive hydrogel for bone regeneration applications. This hydrogel consisted of chitosan, alginate and hydroxyapatite, and was loaded with zoledronic acid as a model drug. The feasibility of three-dimensional (3D) printing of the thermosensitive hydrogel using the extrusion based technique was investigated. The 3D printing technique called Freeform Reversible Embedded Suspended Hydrogel (FRESH) printing was employed for this purpose. To characterize the composite hydrogels, several tests were conducted. The gelation time, rheological properties, and in vitro drug release were analyzed. Additionally, the cell viability test on human osteosarcoma MG-63 cells for the composite hydrogel was assessed using an MTT assay. The results of the study showed that the zoledronic acid-loaded composite thermosensitive hydrogel was successfully printed using the FRESH 3D printing technique which was not possible otherwise i.e., by using traditional 3D printing techniques. Further examination of the printed constructs using a Scanning Electron Microscope revealed the presence of porous and layered structures. The gelation times of the composite thermosensitive hydrogel was determined to be 10 and 20 min, respectively for scaffolds with and without HA, indicating the successful formation of the gel within a reasonable time to the FRESH technique. The flow behavior of the hydrogel was found to be pseudoplastic, following a non-Newtonian flow pattern with Farrow's constant (N) values of 1.708 and 1.853 for scaffolds with and without hydroxyapatite, respectively. In terms of drug release, scaffolds prepared with and without hydroxyapatite reached nearly 100% of zoledronic acid release in 360 h and 48 h, respectively. The cell viability test on human osteosarcoma MG-63 cells using MTT assay has shown increased cell viability % in the case of composite hydrogel, indicating biocompatibility of the scaffold. Overall, this study successfully developed a composite thermosensitive hydrogel loaded with zoledronic acid for bone regeneration applications and was 3D printed using the FRESH 3D printing technique. The results of this study provide valuable insights into the potential use of this composite hydrogel for future biomedical applications.

Developing and Characterizing a Biocompatible Hydrogel Obtained by Cross-Linking Gelatin with Oxidized Sodium Alginate for Potential Biomedical Applications

The main goal of this research was to create biocompatible hydrogels using gelatin and a double cross-linking technique involving both covalent and ionic bonds to immobilize propolis. The covalent bonds were formed through Schiff base cross-links between protein-free amino groups (NH2) from the lysine residue and aldehyde groups (CHO) produced by oxidizing sodium alginate with NaIO4, while the ionic bonds were achieved using Mg2+ ions. Hydrogel films were obtained by varying the molar ratios of -CHO/-NH2 under different pH conditions (3.5 and 5.5). The presence of aldehyde groups in the oxidized sodium alginate (OSA) was confirmed using FTIR and NMR spectroscopy. The oxidation degree was monitored over 48 h, and the influence of temperature was examined. Results showed that higher -CHO/-NH2 molar ratios led to increased conversion index values of NH2 groups, and a decrease in swelling degree values was observed in mediums with pH values of 5.5 and 7.4. The encapsulation and release efficiency of propolis decreased with an increase in the hydrogel cross-linking degree. UV irradiation enhanced the antioxidant activity of both free and encapsulated propolis. These findings offer valuable insights for the biomedical and pharmaceutical fields into designing biocompatible hydrogels for propolis immobilization, with potential for controlled release.

Vancomycin-Loaded in situ Gelled Hydrogel as an Antibacterial System for Enhancing Repair of Infected Bone Defects

Purpose

During treatment of infected bone defects, control of infection is necessary for effective bone repair, and hence controlled topical application of antibiotics is required in clinical practice. In this study, a biodegradable drug delivery system with in situ gelation at the site of infection was prepared by integrating vancomycin into a polyethylene glycol/oxidized dextran (PEG/ODEX) hydrogel matrix.

Methods

In this work, PEG/ODEX hydrogels were prepared by Schiff base reaction, and vancomycin was loaded into them to construct a drug delivery system with controllable release and degradability. We first examined the microstructure, degradation time and drug release of the hydrogels. Then we verified the biocompatibility and in vitro ability of the release system. Finally, we used a rat infected bone defect model for further experiments.

Results

The results showed that this antibacterial system could be completely biodegradable in vivo for 56 days, and its degradation products did not cause specific inflammatory response. The cumulative release of vancomycin from the antibacterial system was 58.3% ± 3.8% at 14 days and 78.4% ± 3.2% at 35 days. The concentration of vancomycin in the surrounding environment was about 1.2 mg/mL, which can effectively remove bacteria. Further studies in vivo showed that the antibacterial system cleared the infection and accelerated repair of infected bone defects in the femur of rats. There was no infection in rats after 8 weeks of treatment. The 3D image analysis of the experimental group showed that the bone volume fraction (BV/TV) was 1.39-fold higher (p < 0.001), the trabecular number (Tb.N) was 1.31-fold higher (p < 0.05), and the trabecular separation (Tb.Sp) was 0.58-fold higher than those of the control group (p < 0.01).

Conclusion

In summary, this study clearly demonstrates that a clinical strategy based on biological materials can provide an innovative and effective approach to treatment of infected bone defects.

The Diels-Alder Cross-Linked Gelatin/Dextran Nanocomposite Hydrogels with Silver Nanoparticles for Wound Healing Applications: Synthesis, Characterization, and In Vitro Evaluation

Wound healing involves a sophisticated biological process that relies on ideal conditions to advance through various stages of repair. Modern wound dressings are designed to imitate the natural surroundings around cells and offer properties such as moisture regulation, strength, and antimicrobial defense to boost healing. A recent research project unveiled a new type of gelatin (Gel)/dextran (Dex) hydrogels, linked through Diels-Alder (D-A) reactions, loaded with silver nanoparticles (Ag-NPs) for cutting-edge wound treatment. Gel and Dex were chemically modified to form the hydrogels via the D-A reaction. The hydrogels were enriched with Ag-NPs at varying levels. Thorough analyses of the hydrogels using methods like NMR, FT-IR, and SEM were carried out to assess their structure and nanoparticle integration. Rheological tests displayed that the hydrogels had favorable mechanical attributes, particularly when Ag-NPs were included. The hydrogels demonstrated controlled swelling, responsiveness to pH changes, and were non-toxic. Testing against E. coli showcased the strong antibacterial activity of the nanocomposite hydrogels in a concentration-dependent manner. This investigation showcased the promise of these bioactive nanocomposite hydrogels in promoting speedy wound healing by maintaining a moist environment, offering an antimicrobial shield, and ensuring mechanical support at the wound site.

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.

Rhizobial oxidized 3-hydroxylbutanoyl glycan-based gelatin hydrogels with enhanced physiochemical properties for pH-responsive drug delivery

Rhizobial exopolysaccharide (EPS) is an acidic polysaccharide involved in nitrogen fixation-related signal transduction in the rhizosphere, serving as a structural support for biofilms, and protecting against various external environmental stresses. Rhizobial EPS as a hydrogel biomaterial was used for a pH-responsive drug delivery system combing with gelatins. Pure gelatin (GA) hydrogels have limited practical applications due to their poor mechanical strength and poor thermal stability. We developed new GA hydrogels using oxidized 3-hydroxylbutanoyl glycan (OHbG) as a polymer cross-linking agent to overcome these limitations. OHbG was synthesized from sodium periodate oxidation of 3-hydroxylbutanoyl glycan directly isolated from Rhizobium leguminosarum bv. viciae VF39. The newly fabricated OHbG/GA hydrogels exhibited 21-fold higher compressive stress and 4.7-fold higher storage modulus (G') than GA at the same strain. This result suggested that OHbG provided mechanical improvement. In addition, these OHbG/GA hydrogels showed effective pH-controlled drug release for 5-fluorouracil, self-healable, and self-antioxidant capacity by uronic acids of OHbG. Cell viability tests using HEK-293 cells in vitro also showed that the OHbG/GA hydrogels were non-toxic. This suggests that the new OHbG/GA hydrogels can be used as a potentially novel biomaterial for drug delivery based on its self-healing ability, antioxidant capacity, and pH-responsive drug delivery.