Injectable, Self-Healing, and Biocompatible N,O-Carboxymethyl Chitosan/Multialdehyde Guar Gum Hydrogels for Sustained Anticancer Drug Delivery

Injectable and implantable hydrogels for localized delivery of drugs and nanomaterials for cancer chemotherapy: A review

Multiple chemotherapeutic strategies have been developed to tackle the complexity of cancer. Still, the outcome of chemotherapeutic regimens remains impaired by the drugs' weak solubility, unspecific biodistribution and poor tumor accumulation after systemic administration. Such constraints triggered the development of nanomaterials to encapsulate and deliver anticancer drugs. In fact, the loading of drugs into nanoparticles can overcome most of the solubility concerns. However, the ability of systemically administered drug-loaded nanomaterials to reach the tumor site has been vastly overestimated, limiting their clinical translation. The drugs' and drug-loaded nanomaterials' systemic administration issues have propelled the development of hydrogels capable of performing their direct/local delivery into the tumor site. The use of these macroscale systems to mediate a tumor-confined delivery of the drugs/drugs-loaded nanomaterials grants an improved therapeutic efficacy and, simultaneously, a reduction of the side effects. The manufacture of these hydrogels requires the careful selection and tailoring of specific polymers/materials as well as the choice of appropriate physical and/or chemical crosslinking interactions. Depending on their administration route and assembling process, these matrices can be classified as injectable in situ forming hydrogels, injectable shear-thinning/self-healing hydrogels, and implantable hydrogels, each type bringing a plethora of advantages for the intended biomedical application. This review provides the reader with an insight into the application of injectable and implantable hydrogels for performing the tumor-confined delivery of drugs and drug-loaded nanomaterials.

Synthesis of Acidic Phosphonic Chitosan and the Complexation of La(III) in Acidic Aqueous Solution

Due to the similar physicochemical properties of rare earth ions, their separation presents significant challenges. In this study, acidic phosphonic chitosan (aPCS) was prepared by modifying chitosan with phosphite and formaldehyde for improving the water solubility and complexing ability of rare earth ions in acidic aqueous solutions. DFT calculations revealed that its phosphonic groups serve as preferred reaction sites, forming stable bidentate complexes with rare earth cations. The complexation abilities of aPCS and phosphorylated chitosan (PCS) for La(III) were compared at various pHs by complexation-ultrafiltration. The results showed that aPCS achieved a 97% rejection for La(III), while 70% for PCS at pH 5 and P/RE 10. Furthermore, aPCS maintained higher rejection than PCS at pH of 3 to 7. In conclusion, aPCS demonstrates excellent potential for the selective extraction and purification of rare earth ions.

Development of a Multi-Stimuli-Responsive Magnetic Nanogel-Hydrogel Nanocomposite for Prolonged and Controlled Doxorubicin Release

The development of advanced drug delivery systems that offer precise, controlled, and sustained release of therapeutic agents remains a significant challenge, particularly for applications in oncology where effective targeting and prolonged drug exposure are essential. We synthesized and characterized a multistimuli-responsive magnetic nanogel-hydrogel nanocomposite (MNHNC) designed for controlled and extended drug release, with an emphasis on anticancer drug delivery. The MNHNC was developed by incorporating poly(N-isopropylacrylamide-co-acrylamide) (p(NIPAM-co-AAm)) nanogels (NGs) within a net-shaped salep-grafted poly(acrylic acid) (PAA) hydrogel matrix, coupled with in situ formation of Fe3O4 nanoparticles to introduce magnetic responsiveness and serve as a cross-linking agent. The nanocomposite exhibited notable swelling capabilities, achieving equilibrium values of 706 g/g at pH 9 (25 °C) and 603 g/g at physiological temperature (37 °C, pH 7.4). Additionally, MNHNC demonstrated responsiveness to pH, temperature, and magnetic fields, facilitating controlled drug release. Using doxorubicin (DOX) as a model drug, MNHNC exhibited dual pH sensitivity (NG at pH 5.4 and MNHNC at pH 7.4) and achieved a prolonged release profile of 400 h, significantly surpassing conventional systems, including our previous nanocomposite. Release kinetics followed a super case-II transport mechanism, where swelling primarily governed drug diffusion. Furthermore, the application of a magnetic field enabled fine-tuning of the release rate, offering an additional layer of control. The kinetic study indicated that the drug release from MNHNC followed zero-order kinetics under certain conditions, ensuring a consistent release rate over time, which is highly desirable for maintaining therapeutic efficacy. The Korsmeyer-Peppas model further confirmed the super case-II transport mechanism, highlighting the significant influence of polymer relaxation and swelling on the release process. The Hixson-Crowell model also demonstrated the role of matrix erosion in the drug release mechanism. The results showed a marked improvement in pH and temperature sensitivity compared to previous formulations, enhanced mechanical stability due to the integration of Fe3O4 nanoparticles, and the ability to modulate drug release through external magnetic fields. In vitro cytotoxicity assessment using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay demonstrated the biocompatibility of the MNHNC, with over 95% cell viability in the absence of DOX, confirming its nontoxic nature. Upon DOX loading, MNHNC exhibited a proper anticancer effect against cancer cell lines, showing a dose-dependent reduction in cell viability. The robust mechanical stability, biocompatibility, and multistimuli responsiveness of MNHNC position it as a promising candidate for advanced, targeted drug delivery systems.

Janus asymmetric galactomannan-based hydrogel with programmable deformation for accelerating wound healing

The development of an asymmetrical engineering dressing that accelerates wound closure is crucial for clinical applications. The hydrogel with a Janus structure that integrates thermo-responsive contraction and adhesive properties was fabricated through a robust cross-linked network of isopropylacrylamide and polyacrylamide, while a functional surface layer was created by cross-linking zwitterionic monomers and hyaluronic acid. The hydrogel exhibited superior tensile stress (80 Kpa), fracture strain (3000 %), tissue adhesiveness (35 Kpa) and high antibacterial activity (with a 99.9 % reduction in bacterial growth). The Janus hydrogel demonstrated significant thermal responsiveness and self-contraction properties, contributing to accelerated wound closure. In vivo experiments showed that the Janus hydrogel facilitated sutureless wound closure and enhanced wound healing through mechanical inward force, significantly improving wound contraction and promoting granulation tissue formation, as well as collagen deposition, resulting in 99 % wound healing efficiency by day 14. These results underscore the novel design of the Janus hydrogel as a multifunctional wound dressing, offering a unique combination of thermo-responsive and adhesive properties, along with excellent antibacterial and healing-promoting effects, making it a promising candidate for clinical wound repair.

Cyclodextrin modified biocompatible Chitosan-Cinnamaldehyde Schiff base hydrogels: Their antibacterial, antioxidant, and drug delivery potential

Chitosan (CS)-based hydrogels are promising platforms for drug delivery owing to their biocompatibility, biodegradability, and functional versatility. However, pure CS Schiff base hydrogels lack mechanical strength and rely on toxic cross-linkers, necessitating bio-safe alternatives viz. Cinnamaldehyde (CA). In this study, hybrid Chitosan-Cinnamaldehyde (CSCA) and Chitosan-Cinnamaldehyde-γ-Cyclodextrin (CSCDCA) hydrogels were synthesized to address the limitations. Encapsulation of CA into γ-Cyclodextrin (γ-CD) enhanced the stability of CA through the formation of an inclusion complex (IC), as confirmed by NMR analysis. CSCDCA hydrogels although relatively weaker, exhibited superior swelling/water retention capability over CSCA hydrogels. The release behavior of Rifampicin (Rif) a model hydrophobic drug, was monitored in both hydrogels. CSCDCA hydrogel showed more controlled release (∼56 % at pH 2 and 39 % at pH 7.4 over 30 h) compared to CSCA (∼70 % at pH 2 and 36 % at pH 7.4). Kinetic analysis indicated combined diffusion and relaxation mechanism of release. Antibacterial and antioxidant (AOX) activities confirmed significant activity, with CSCDCA achieving 95 % cell viability against human embryonic kidney (HEK-293) cells. These findings underscore the hydrogel's suitability as pH-sensitive drug delivery system (DDS), enhancing Rif's bioavailability, minimizing side effects, and establishing a benchmark for eco-friendly hydrogels in therapeutic applications.

Self-healing adhesive oxidized guar gum hydrogel loaded with mesenchymal stem cell exosomes for corneal wound healing

Hydrogels have shown great potential and value in wound healing. In this study, we construct a mesenchymal stem cell exosomes (MSC-Exos) laden natural biopolymer-based hydrogel with transparent, self-healing, injectable, and tissue adhesive properties to promote corneal regeneration. This hydrogel is synthesized by combining aldehyde-modified oxidized guar gum (OGG) and carboxymethyl chitosan (CMCS) through the dynamic, reversible Schiff base bonds, which endow it with outstanding shear-thinning and self-healing properties, facilitating easy injection through a needle. The physicochemical properties, such as porosity, mechanical strength, and light transmittance, could be precisely tunable by adjusting OGG concentrations. The resultant hydrogel achieves robust tissue adhesion at physiological temperatures due to Schiff base interactions. Besides, the Exos can be uptaken by the corneal epithelial cells and subsequently promote the migration of the cells. We have proven that the MSC-Exos-loaded hydrogel adheres firmly to the defected cornea and significantly improves wound repair by enhancing collagen deposition and reducing inflammation in a rabbit cornea defect model. These results indicated that this multifunctional hydrogel holds immense scientific promise and offers a wide range of clinical applications.

Temperature-Triggered Reversible Adhesion Hydrogel with Responsive Drug Release, Mild Photothermal Therapy, and Biofilm Clearance for Skin Infection Healing

Bacterial infection gives rise to a hypoxic, H2O2-abundant, and acidic local microenvironment at the site of inflammation, which prevents the healing of skin tissues. In this work, gelatin and oxidized carboxymethyl cellulose were developed as the framework of hydrogels. Tannic acid and 3-formylphenylboronic acid served as small-molecule anchors. Through the introduction of multiple dynamic cross-linkings, the hydrogel was endowed with various functions. These functions encompassed mechanical compatibility with the skin, reversible adhesion characteristics, and rapid self-healing capabilities. In addition, nanoflower-like MnO2 microparticles loaded with berberine hydrochloride were embedded. MnO2 has the ability not only to kill bacteria through the photothermal effect (PTT) but also to catalyze the decomposition of H2O2 and release oxygen, effectively improving the inflammatory microenvironment. Remarkably, based on the drug/PTT synergistic strategy, the hydrogel exhibited significant antibacterial activity and biofilm removal ability under mild conditions (<50 °C), avoiding thermal damage to healthy tissues. Consequently, the hydrogels demonstrate favorable biocompatibility, significant cell proliferation, migration, angiogenesis, collagen deposition, and tissue regeneration. Therefore, the multifunctional antimicrobial hydrogel is expected to be a skin-friendly medical dressing with enormous potential in the treatment of skin and soft tissue infections.

Chitosan and hyaluronic acid in breast cancer treatment: Anticancer efficacy and nanoparticle and hydrogel development

The pervasive global health concern of breast cancer necessitates the development of innovative therapeutic interventions to enhance efficacy and mitigate adverse effects. Chitosan and hyaluronic acid, recognized for their biocompatibility and biodegradability, present compelling options for the novel drug delivery systems and therapeutic platforms in the context of breast cancer management. This review will delineate the distinctive attributes of chitosan and hyaluronic acid, encompassing their inherent anticancer properties, targeting capabilities, and suitability for chemical modifications along with nanoparticle development. These characteristics render them exceptionally well-suited for the fabrication of nanoparticles and hydrogels. The intrinsic anticancer potential of chitosan, in conjunction with its mucoadhesive properties, and the robust binding affinity of hyaluronic acid to CD44 receptors, facilitate specific drug delivery to the malignant cells, thus circumventing the limitations inherent in traditional treatment modalities such as chemotherapy. The incorporation of these materials into nanocarriers allows for the co-delivery of therapeutic agents, thereby potentiating synergistic effects, while hydrogel systems provide localized, controlled drug release and facilitate tissue regeneration. An analysis of advancements in their synthesis, functionalization, and application is presented, while also acknowledging challenges pertaining to scalability and clinical translation.

Intratumoral delivery of Mitomycin C using bio-responsive Gellan Gum Nanogel: In-vitro evaluation and enhanced chemotherapeutic efficacy

Intratumoral drug delivery systems hold immense promise in overcoming the limitations of conventional IV chemotherapy, particularly in enhancing therapeutic efficacy and minimizing systemic side effects. In this study, we introduce a novel redox-responsive intratumoral nanogel system that combines the biocompatibility of natural polysaccharides with the tailored properties of synthetic polymers. The nanogel features a unique cross-linked architecture incorporating redox-sensitive segments, designed to leverage the elevated glutathione levels in the tumor microenvironment for controlled drug release. Synthesis was performed using a microwave-assisted free radical polymerization technique, which facilitated efficient and rapid cross-linking. A Quality by Design strategy was implemented to optimize key parameters, ensuring the nanogel's suitability for intratumoral delivery, including ideal injectability, viscosity, and drug release characteristics. Mitomycin C (MMC), a chemotherapeutic agent effective against hypoxic tumor cells, was efficiently loaded within the cross-linked nanogel. Optimal stability and drug loading were achieved at a 2:1 nanogel/MMC ratio. The nanogel's structure and composition were confirmed using elemental analysis, FTIR, NMR spectroscopy, and XRD. Stability studies demonstrated its robustness in simulated physiological conditions. In vitro evaluations revealed enhanced cellular uptake of the MMC-loaded nanogel, leading to effective cell cycle arrest, mitochondrial membrane potential disruption, and apoptosis, Co-localization studies with Lysotracker Green, a lysosomal marker, revealed that the nanogels were trafficked to lysosomes. Pharmacokinetic analysis showed significantly reduced systemic exposure (lower plasma Cmax) compared to intravenous administration, while biodistribution studies using IVIS imaging demonstrated prolonged retention of the nanogel within tumor tissues. In vivo studies using a 4T1 xenograft mouse model highlighted the superior antitumor efficacy of the intratumoral nanogel system compared to free MMC. The nanogel treatment resulted in significant tumor volume reduction, minimal changes in body weight, and reduced lung metastasis, as confirmed by histological analysis (HE staining). Ki67 and TUNEL assays of tumor tissues further substantiated the nanogel's ability to suppress proliferation and induce apoptosis. These outcomes directly correlate with our goal of using a redox responsive nanogel system to improve localized drug delivery and minimize systemic side effects. This biodegradable, redox-responsive polymer system represents a significant advance in nanomedicine, offering a promising platform for safe and effective localized cancer therapy.

A Simple Method to Determine Diffusion Coefficients in Soft Hydrogels for Drug Delivery and Biomedical Applications

Biomedical applications of hydrogels are rapidly increasing due to their special properties including high water absorption capacity, viscoelasticity, swelling capability, and responsiveness to environmental physical or chemical stimuli. Two major biomedical applications of hydrogels include drug delivery and tissue engineering. Knowledge of the diffusion or degree of penetration of particles in hydrogels is key to designing specific functions such as controlled release in drug delivery systems and nutrient accessibility in tissue engineering platforms. Experimental determination of solute penetration and diffusivity can be challenging depending on several factors such as the hydrogelation process, the hydrogel characteristics, and the type of diffusing particle. We describe here a simple method that uses fluorescence intensity measurements obtained with a microplate reader to determine the concentration of diffusing particles at different penetration distances in soft hydrogels. We have analyzed the diffusion behavior of three fluorescent particles of different chemical natures and various molecular weights (fluorescein and the proteins mNeonGreen and fluorophore-labeled bovine serum albumin) in agarose hydrogels of low percentages (0.05-0.2%). The diffusion coefficients were obtained by fitting the experimental data to a one-dimensional diffusion model. A good agreement between our results and previously reported diffusion coefficients of the studied particles validates our method. We demonstrate the method's capability to adapt to hydrogels of different stiffnesses and solutes of various sizes and characteristics. In addition, the combination of hydrogel sectioning with multiple simultaneous measurements in a microplate reader shows the simplicity of the experimental procedure. Finally, our data indicate the method's sensitivity to variations in diffusion conditions, which is highly relevant to studying interactions between solutes and hydrogels designed for controlled release by determining differences in penetration distances.

Implantable Polymer Scaffolds Loaded with Paclitaxel-Cyclodextrin Complexes for Post-Breast Cancer Tissue Reconstruction

The side effects associated with the chemotherapy of triple-negative breast cancer (TNBC), such as nucleotide-binding oligomerization domain (NOD)-like receptor family (NLR), pyrin domain containing 3 (NLRP3) inflammasome activity, are responsible for the treatment failure and high mortality rates. Therefore, advanced delivery systems have been developed to improve the transport and targeted administration of anti-tumor agents at the tumor sites using tissue engineering approaches. Implantable delivery systems based on biodegradable polymers are an effective alternative due high biocompatibility, porosity, and mechanical strength. Moreover, the use of paclitaxel (PTX)-cyclodextrin complexes increases the solubility and permeability of PTX, enhancing the bioavailability and efficacy of the drug. All of these properties contribute to the efficient encapsulation and controlled release of drugs, preventing the damage of healthy tissues. In the current study, we detailed the synthesis process and evaluation of 3D scaffolds based on gelatin functionalized with methacryloyl groups (GelMA) and pectin loaded with PTX-cyclodextrin inclusion complexes on TNBC pathogenesis in vitro and in vivo. Bio-physio-chemical analysis of the proposed scaffolds revealed favorable mechanical and biological properties for the cellular component. To improve the drug solubility, a host-guest interaction was performed by the complexation of PTX with a cyclodextrin derivative prior to scaffold synthesis. The presence of PTX suppressed the growth of breast tumor cells and promoted caspase-1 activity, the release of interleukin (IL)-1β, and the production of reactive oxygen species (ROS), conditioning the expression levels of the genes and proteins associated with breast tumorigenesis and NLRP3 inflammasome. The in vivo experiments suggested the activation of pyroptosis tumor cell death, confirming the in vitro experiments. In conclusion, the bio-mechanical properties of the GelMA and pectin-based scaffolds as well as the addition of the PTX-cyclodextrin complexes allow for the targeted and efficient delivery of PTX, suppressing the viability of the breast tumor cells via pyroptosis cell death initiation.

A slime-inspired phycocyanin/κ-carrageenan-based hydrogel bandage with ultra-stretchability, self-healing, antioxidative, and antibacterial activity for wound healing

Hydrogels have attracted extensive attention as wound dressing owing to their excellent multifunctionality, flexibility, and biocompatibility. Due to the frequent movement and stretching of skin as well as complex surface of wound, traditional wound dressings have difficulty to adapt to motion and irregular wounds. Furthermore, excessive reactive oxygen species (ROS) and bacterial infection can induce delayed wound healing. To this end, we developed a set of versatile phycocyanin-based dual network hydrogels (PPC hydrogels) with polyvinyl alcohol (PVA) and κ-carrageenan (CRG) as substrate via forming of borate ester bonds, hydrogen bonds, and electrostatic interaction. The PPC hydrogels not only possessed adaptivity, ultra-stretchability (7036.12 %), efficient self-healing and injectability, but also possessed antioxidative and antibacterial capacities conferred by C-phycocyanin (PC) and rhein. Moreover, the hydrogels also exhibited excellent hemostatic ability and high biocompatibility. More remarkably, the PPC-I hydrogel could accelerate wound healing by effect of anti-inflammation (downregulating TNF-α and IL-6) and promoting collagen deposition and angiogenesis (upregulating CD31), which may be utilized as hydrogel bandages and applied to motion and irregular wounds, thereby promising the application prospect of the hydrogels as wound dressing.

Mechanically improved chitosan/graphene oxide nanocomposite hydrogel for sustained release of levofloxacin

This study introduces a novel chitosan/graphene oxide (CS/GO) nanocomposite hydrogel designed for the sustained release of levofloxacin. The hydrogel was synthesized using electrostatic interactions and chemical cross-linking, resulting in significant mechanical reinforcement (G' = 0.94 MPa, G" = 0.088 MPa) and homogeneous distribution of GO. It exhibited excellent swelling properties (1380 % at 0.05 wt% GO, 1070 % at 0.2 wt% GO at pH 2). Levofloxacin release was faster (∼95 % in 5 h) at 0.05 wt% GO and more sustained (∼97 % over 24 h) at 0.2 wt% GO. This hydrogel demonstrates potential as a robust platform for controlled drug delivery.

A chitosan/gelatin/aldehyde hyaluronic acid hydrogel coating releasing calcium ions and vancomycin in pH response to prevent the formation of bacterial biofilm

Osteomyelitis is a refractory disease of orthopedics, part of which is caused by medical implants. The main difficulties in treatment are the barrier effect after the formation of bacterial biofilm, and the difficulty in achieving sustained antibiotic intervention. In view of this situation, we studied a hydrogel coating that can release CaCl2 and vancomycin in pH-responsive manner. We used nano-TiO2 to modify Chitosan/ Gelatin/Aldehyde Hyaluronic Acid (CS/Gel/AHA) hydrogel, and combined with the dip-coating technique, prepared a coating with good mechanical strength. The hydrogel-loaded zeolitic imidazolate framework (ZIF) decomposes under acidic conditions, and the released Ca2+ act on the bacterial Bap protein to inhibit the formation of biofilm, and the released vancomycin kills free bacteria. The antibacterial coating achieved good bactericidal effect in both in vitro experiments and rat subcutaneous implant model. These results not only provide a new way to enhance the strength of hydrogels to prepare coatings, but also utilize a new approach to responsively inhibit the formation of biofilms, showing the promising application prospects of the coating in antibacterial treatment of medical implants.

A comprehensive review on guar gum and its modified biopolymers: Their potential applications in tissue engineering

Guar gum (GG), as a non-exudate gum, is extracted from the seed's embryos of Cyamopsis tetragonoloba (a member of Leguminosae family). Recently, this biopolymer has received extensive attention due to its low cost, notable properties, non-toxic biodegradation, ease of availability, and biocompatibility. However, disadvantages such as uncontrolled hydration rate and susceptibility to microbial attack have led many researchers to further modification of guar gum. Further modifications of guar gum heteropolysaccharide have been performed to improve properties and explore and expand its potential. The favorable biostability, improved solubility, and swelling, increased pH sensitivity, and good antibacterial and antioxidant properties indicate the significant advantages of the modified gum structures with different functional groups. In this review, the rapid growth in research on GG derivatives-based materials has been discovered. Besides, the production methods of GG and its derivatives have been discussed in tissue engineering and regenerative medical. Consequently, this review highlights the advances in the production of guar-based products to outline a promising future for this biopolymer by changing its properties and expanding its applications in potential targets.

Advances in polysaccharide-based materials for biomedical and pharmaceutical applications: A comprehensive review

Polysaccharides, the most abundant biopolymers in nature, have attracted the attention of researchers and clinicians due to its practicality in biomedical and pharmaceutical sciences. These biomaterials have high bioavailability and play structural and functional roles in living organisms. Polysaccharides are classified into several groups based on their origin, including plant polysaccharides and marine polysaccharides (like chitosan, hyaluronic acid, dextran, alginates, etc.) with specific applications. These biopolymers possess unique physicochemical (such as surface functional groups, solubility, and stability), mechanical (like mechanical strength and tensile), and biomedical (such as antioxidant activity, biocompatibility, biodegradability, renewability, and non-immunogenicity) characteristics which have made them excellent platforms for a wide variety of biomedical and pharmaceutical applications. Ease of extraction and different preparation approaches are mentioned as other potential properties of polysaccharides that further improved their practicality in biomedical sciences. They have high drug/bioactive encapsulation capacity and sustained/controlled release manner in in vivo microenvironments. The anti-inflammatory and immunomodulation, stimuli-responsive drug/bioactive release, and passive and active drug/bioactive delivery are considered the potential features of these biopolymers in pharmaceutical sciences. Polysaccharides have indicated practical applications in biomedical sciences, including biosensors, tissue engineering, implantation, wound healing, vascular grafting, and vaccines. This review highlights the advances of polysaccharide-based materials in biomedical and pharmaceutical sciences.

Application of polysaccharide-based crosslinking agents based on schiff base linkages for biomedical scaffolds

Chemical crosslinking is a method widely used to enhance the mechanical strength of biopolymer-based scaffolds. Polysaccharides are natural and biodegradable carbohydrate polymers that can act as crosslinking agents to promote the formation of scaffolds. Compared to synthetic crosslinking agents, Polysaccharide-based crosslinking agents have better biocompatibility for cell adhesion and growth. Traditional Chinese medicine has special therapeutic effects on various diseases and is rich in various bioactive ingredients. Among them, polysaccharides have immune regulatory, antioxidant, and anti-inflammation effects, which allow them to not only act as crosslinking agents but endow the scaffold with greater bioactivity. This article focuses on the latest developments of polysaccharide-based crosslinking agents for biomedical scaffolds, including hyaluronic acid, chondroitin sulfate, dextran, alginate, cellulose, gum polysaccharides, and traditional Chinese medicine polysaccharides. Also, we provide a summary and prospects on the research of polysaccharide-based crosslinking agents.

Alginate-based hydrogels mediated biomedical applications: A review

With the development in the field of biomaterials, research on alternative biocompatible materials has been initiated, and alginate in polysaccharides has become one of the research hotspots due to its advantages of biocompatibility, biodegradability and low cost. In recent years, with the further understanding of microscopic molecular structure and properties of alginate, various physicochemical methods of cross-linking strategies, as well as organic and inorganic materials, have led to the development of different properties of alginate hydrogels for greatly expanded applications. In view of the potential application prospects of alginate-based hydrogels, this paper reviews the properties and preparation of alginate-based hydrogels and their major achievements in delivery carrier, dressings, tissue engineering and other applications are also summarized. In addition, the combination of alginate-based hydrogel and new technology such as 3D printing are also involved, which will contribute to further research and exploration.

Advances in stimuli-responsive injectable hydrogels for biomedical applications

Injectable hydrogels, as a class of highly hydrated soft materials, are of interest for biomedicine due to their precise implantation and minimally invasive local drug delivery at the implantation site. The combination of in situ gelation ability and versatile therapeutic agent/cell loading capabilities makes injectable hydrogels ideal materials for drug delivery, tissue engineering, wound dressing and tumor treatment. In particular, the stimuli-responsive injectable hydrogels that can respond to different stimuli in and out of the body (e.g., temperature, pH, redox conditions, light, magnetic fields, etc.) have significant advantages in biomedicine. Here, we summarize the design strategies, advantages, and recent developments of stimuli-responsive injectable hydrogels in different biomedical fields. Challenges and future perspectives of stimuli-responsive injectable hydrogels are also discussed and the future steps necessary to fulfill the potential of these promising materials are highlighted.

Florfenicol core-shell composite nanogels as oral administration for efficient treatment of bacterial enteritis

To reduce the bitterness of florfenicol, avoid its degradation by gastric acid, and enhance its antibacterial activity against Escherichia coli by targeting and slowly releasing drugs at the site of intestinal infection, with pectin as an anion carrier and chitosan oligosaccharides (COS) as a cationic carrier, florfenicol-loaded COS@pectin core nanogels were self-assembled by electrostatic interaction and then encapsulated in sodium carboxymethylcellulose (CMCNa) shell nanogels through the complexation of CMCNa and Ca2+ to prepare florfenicol core-shell composite nanogels in this study. The florfenicol core-shell composite nanogels were investigated for their formula choice, physicochemical characterization, pH-responsive performances, antibacterial activity, therapeutic efficacy, and in vitro and in vivo biosafety studies. The results indicated that the optimized formula was 0.6 g florfenicol, 0.79 g CMCNa, 0.30 g CaCl2, 0.05 g COS, and 0.10 g pectin, respectively. In addition, the mean particle diameter, polydispersity index, zeta potential, loading capacity, and encapsulation efficiency were 124.0 ± 7.2 nm, -22.9 ± 2.5 mV, 0.42 ± 0.03, 43.4 % ± 3.1 %, and 80.5 % ± 3.4 %, respectively. The appearance, lyophilized mass, resolvability, scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and fourier transform infrared (FTIR) showed that the florfenicol core-shell composite nanogels were successfully prepared. Florfenicol core-shell composite nanogels had satisfactory stability, rheology, and pH-responsiveness, which were conducive to avoid degradation by gastric acid and achieve targeted and slow release at intestinal infection sites. More importantly, florfenicol core-shell composite nanogels had excellent antibacterial activity against Escherichia coli, a satisfactory therapeutic effect, and good palatability. In vitro and in vivo biosafety studies suggested the great promise of florfenicol core-shell composite nanogels. Therefore, the prepared florfenicol core-shell composite nanogels may be helpful for the treatment of bacterial enteritis as a biocompatible oral administration.

Multibiofunctional Self-healing Adhesive Injectable Nanocomposite Polysaccharide Hydrogel

Injectable hydrogels with good antimicrobial and antioxidant properties, self-healing characteristics, suitable mechanical properties, and therapeutic effects have great practical significance for developing treatments for pressing healthcare challenges. Herein, we have designed a novel, self-healing injectable hydrogel composite incorporating cross-linked biofunctional nanomaterials by mixing alginate aldehyde (Ox-Alg), quaternized chitosan (QCS), adipic acid dihydrazide (ADH), and copper oxide nanosheets surface functionalized with folic acid as the bioligand (F-CuO). Gelation was achieved under physiological conditions via the dynamic Schiff base cross-linking mechanism. The developed nanocomposite injectable hydrogel demonstrated the fast self-healing ability essential to bear deformation and outstanding antibacterial properties along with ROS scavenging ability. Furthermore, the optimized formulation of our F-CuO-embedded injectable hydrogel exhibited excellent cytocompatibility, blood compatibility, and in vitro wound healing performance. Taken together, the F-CuO nanosheet cross-linked injectable hydrogel composite presented herein offers a promising candidate biomaterial with multifunctional properties to develop solutions for addressing clinical challenges.

Stimuli-responsive biomaterials: smart avenue toward 4D bioprinting

3D bioprinting is an advanced technology combining cells and bioactive molecules within a single bioscaffold; however, this scaffold cannot change, modify or grow in response to a dynamic implemented environment. Lately, a new era of smart polymers and hydrogels has emerged, which can add another dimension, e.g., time to 3D bioprinting, to address some of the current approaches' limitations. This concept is indicated as 4D bioprinting. This approach may assist in fabricating tissue-like structures with a configuration and function that mimic the natural tissue. These scaffolds can change and reform as the tissue are transformed with the potential of specific drug or biomolecules released for various biomedical applications, such as biosensing, wound healing, soft robotics, drug delivery, and tissue engineering, though 4D bioprinting is still in its early stages and more works are required to advance it. In this review article, the critical challenge in the field of 4D bioprinting and transformations from 3D bioprinting to 4D phases is reviewed. Also, the mechanistic aspects from the chemistry and material science point of view are discussed too.

Robust Gradient Hydrogel-Loaded Nanofiber Fleshy Artificial Skin Via A Coupled Microfluidic Electrospinning-Reactive Coating Strategy

Skin regeneration attracts tremendous interest due to the important role of skin for human protection and beauty. Thus, methods allowing artificial skin to be carried out in a controllable fashion are potentially important for wound healing, which involves an intersection of materials, medicine, biology, and other disciplines. Herein, aiming at a new general methodology for fleshy materials, a new hydrogel-loaded hydrophobic-hydrophilic nanofiber fleshy artificial skin is designed and fabricated. The gradient hydrogel-loaded nanofiber artificial skin integrates both advantages of nanofiber and hydrogel, exhibiting fleshy feature (comparability to real skin in terms of appearance, texture, and function), excellent air permeability, compatibility, and good mechanical and antibacterial property. Interestingly, the efficient transport channels are formed throughout the hydrogel-loaded nanofiber structure, which is beneficial for water absorption and transfer. These advantages enable the establishment of a moist and favorable microenvironment; thus, greatly accelerating wound healing process. This work couples microfluidic electrospinning with reactive coating technique, which is in favor of material design and fabrication with controllable and uniform structures. The hydrogel-loaded nanofiber fleshy artificial skin shows comparability to real skin in terms of beauty, texture, and function, which would definitely provide new opportunities for the further optimization and upgrading of artificial skin.

Rapid in situ formation of κ-carrageenan-carboxymethyl chitosan-kaolin clay hydrogel films enriched with arbutin for enhanced preservation of cherry tomatoes

Food waste resulting from perishable fruits and vegetables, coupled with the utilization of non-renewable petroleum-based packaging materials, presents pressing challenges demanding resolution. This study addresses these critical issues through the innovative development of a biodegradable functional plastic wrap. Specifically, the proposed solution involves the creation of a κ-carrageenan/carboxymethyl chitosan/arbutin/kaolin clay composite film. This film, capable of rapid in-situ formation on the surfaces of perishable fruits, adeptly conforms to their distinct shapes. The incorporation of kaolin clay in the composite film plays a pivotal role in mitigating water vapor and oxygen permeability, concurrently bolstering water resistance. Accordingly, tensile strength of the composite film experiences a remarkable enhancement, escalating from 20.60 MPa to 34.71 MPa with the incorporation of kaolin clay. The composite film proves its efficacy by preserving cherry tomatoes for an extended period of 9 days at 28 °C through the deliberate delay of fruit ripening, respiration, dehydration and microbial invasion. Crucially, the economic viability of the raw materials utilized in the film, coupled with the expeditious and straightforward preparation method, underscores the practicality of this innovative approach. This study thus introduces an easy and sustainable method for preserving perishable fruits, offering a cost-effective and efficient alternative to petroleum-based packaging materials.

Self-Healing Guar Gum-Based Nanocomposite Hydrogel Promotes Infected Wound Healing through Photothermal Antibacterial Therapy

Preventing bacterial infections is a crucial aspect of wound healing. There is an urgent need for multifunctional biomaterials without antibiotics to promote wound healing. In this study, we fabricated a guar gum (GG)-based nanocomposite hydrogel, termed GBTF, which exhibited photothermal antibacterial therapy for infected wound healing. The GBTF hydrogel formed a cross-linked network through dynamic borate/diol interactions between GG and borax, thereby exhibiting simultaneously self-healing, adaptable, and injectable properties. Additionally, tannic acid (TA)/Fe3+ nanocomplexes (NCs) were incorporated into the hydrogel to confer photothermal antibacterial properties. Under the irradiation of an 808 nm near-infrared laser, the TA/Fe3+ NCs in the hydrogel could rapidly generate heat, leading to the disruption of bacterial cell membranes and subsequent bacterial eradication. Furthermore, the hydrogels exhibited good cytocompatibility and hemocompatibility, making them a precandidate for preclinical and clinical applications. Finally, they could significantly promote bacteria-infected wound healing by reducing bacterial viability, accelerating collagen deposition, and promoting epithelial remodeling. Therefore, the multifunctional GBTF hydrogel, which was composed entirely of natural substances including guar gum, borax, and polyphenol/ferric ion NCs, showed great potential for regenerating infected skin wounds in clinical applications.

Biodegradable chitin nanofiber-alginate dialdehyde hydrogel: An injectable, self-healing scaffold for anti-tumor drug delivery

Injectable hydrogels fabricated from natural polymers have attracted increasing attentions for their potential in biomedical application owing to the biocompatibility and biodegradability. A new class of natural polymer based self-healing hydrogel is constructed through dynamic covalent bonds. The injectable self-healing hydrogels are fabricated by introducing alginate aldehyde to form Schiff base bonds with the chitin nanofibers. These hydrogels demonstrate excellent self-healing properties, injectability, and pH-responsive sol-gel transition behaviors. As a result, they can serve as carriers to allow an effective encapsulation of doxorubicin (DOX) for drug delivery. Furthermore, these hydrogels exhibit excellent biocompatibility and degradability in vitro and in vivo. The sustained release of DOX from the hydrogels effectively suppresses tumor growth in animal models without causing significant systemic toxicity, suggesting their potential application in anti-tumor therapies.

Chitosan-based injectable hydrogel with multifunction for wound healing: A critical review

Different types of clinical wounds are difficult to treat while infected by bacteria. Wound repair involves multiple cellular and molecular interactions, which is a complicated process. However, wound repair often suffers from abnormal cellular functions or pathways that result in unavoidable side effects, so there is an urgent need for a material that can heal wounds quickly and with few side effects. Based on these needs, hydrogels with injectable properties have been confirmed to be able to undergo self-healing, which provides favorable conditions for wound healing. Notably, as a biopolymer with excellent easy-to-modify properties from a wide range of natural sources, chitosan can be used to prepare injectable hydrogel with multifunction for wound healing because of its outstanding flowability and injectability. Especially, chitosan-based hydrogels with marked biocompatibility, non-toxicity, and bio-adhesion properties are ideal for facilitating wound healing. In this review, the characteristics and healing mechanisms of different wounds are briefly summarized. In addition, the preparation and characterization of injectable chitosan hydrogels in recent years are classified. Additionally, the bioactive properties of this type of hydrogel in vitro and in vivo are demonstrated, and future trend in wound healing is prospected.

Preparation and properties of polyvinyl alcohol/chitosan-based hydrogel with dual pH/NH3 sensor for naked-eye monitoring of seafood freshness

To address the issue of food spoilage causing health and economic loss, we developed a pH/NH3 dual sensitive hydrogel based on polyvinyl alcohol/chitosan (PVA/CS) containing chitosan-phenol red (CP). The CP was synthesized via Mannich reaction and immobilized it in PVA/CS hydrogel through freezing/thawing method to prepare the final PVA/CS/CP hydrogel. The synthesis of CP was confirmed by 1H NMR, FT-IR, XRD, UV-vis, and XPS. The characteristics of hydrogel were evaluated by FT-IR, XRD, SEM, mechanical properties, thermal stability, leaching, and color stability tests. The PVA/CS/CP hydrogel showed distinctly different color at various pH and NH3 vapor levels (yellow to purple). The hydrogel exhibited obvious color changes (ΔE = 46.95) in response to shrimp spoilage, stored at 4 °C. It showed positive and strong correlation between the ΔE values of the indicator hydrogel and total volatile basic nitrogen (TVB-N) as (R2 = 0.9573) and with pH as (R2 = 0.8686), respectively. These results clearly show that the PVA/CS/CP hydrogel could be applied for naked-eye real-time monitoring of seafood freshness in intelligent packaging.

Preparation and antitumor study of intelligent injectable hydrogel: Carboxymethyl chitosan-aldehyde gum Arabic composite graphene oxide hydrogel

In this study, we used polyaldehyde gum Arabic (OGA) and carboxymethyl chitosan (CMCS) as a gel matrix to form an injectable self-healing hydrogel by Schiff-base bonding. Further, graphene oxide (GO) was loaded with doxorubicin (DOX) to the hydrogel, which resulted in a CMCS-OGA/GO@DOX hydrogel. We achieved a DOX drug loading capacity of 43.80 ± 1.13 %. Rheological studies showed that GO hydrogels have improved mechanical properties. The in vitro release profile showed pH responsiveness with 88.21 % DOX release at pH 5.5. Biocompatibility studies showed that the hydrogel composition had good cytocompatibility with L929 cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed a cell survival rate of 93.88 % within 48 h. The DOX-loaded hydrogel exhibited higher cell mortality in breast cancer cells (4 T1), with an inhibition rate of 79.4 % at 48 h. Acridine orange/ethidium bromide staining experiments on 4 T1 cells showed that when loaded with the same DOX concentration, the hydrogel significantly reduced the toxic effects on normal cells, whereas it had significant cytotoxic effects on cancer cells. This result indicates that the prepared GO hydrogel drug delivery system can serve as a novel approach for localized breast cancer treatment.

Synergistic formulation approach for developing pea protein and guar gum enriched olive oil-in-water emulsion gels as solid fat substitutes: Formulation optimization, characterization, and molecular simulation

This study aimed to optimize the formulation of olive oil-in-water (O/W) emulsion gels by incorporating Pea Protein (PP) and Guar Gum (GG) as alternative options for solid fats. The optimum rheological (consistency index, apparent viscosity, recovery) and texture (firmness) properties of the emulsion gels were obtained using a mixture of 2 % PP, 1 % GG, 60 % Olive Oil (OO), and 37 % Water (W). The blend of PP2/GG1 showed the highest results for recovery and firmness, 111.27 % and 33.89 g, respectively. PP/GG blend emulsion gels exhibited higher absolute ζ-potential values, ranging between -72.3 and -77.4 mV. The polydispersity index (PDI) ranged from 0.185 to 0.535, with the most uniform distributions found in the PP/GG blend emulsion gels. Strong phase separation resistance indicated strong stability of PP-GG complex emulsion gels. Higher PP concentrations decreased emulsion oxidation. FTIR and XRD research showed that PP and GG interact strongly, indicating good compatibility. The free binding energy of the most stable configuration of the molecules was -6.8 kcal mol-1, indicating a high affinity. PP interacted with GG through 9 amino acid residues, with notable residues being Asp 224, Thr 235, Ala 332, Ile 334, and Arg 336, and their respective interaction distances ranged between 2.69 Å and 3.87 Å.

Chitosan-functionalized bioplatforms and hydrogels in breast cancer: immunotherapy, phototherapy and clinical perspectives

Breast cancer is the most common and malignant tumor among women. Chitosan (CS)-based nanoparticles have been introduced into breast cancer therapy as a way to increase the targeted delivery of drugs and genes to the tumor site. CS nanostructures suppress tumorigenesis by enhancing both the targeted delivery of cargo (drug and gene) and its accumulation in tumor cells. The tumor cells internalize CS-based nanoparticles through endocytosis. Moreover, chitosan nanocarriers can also induce phototherapy-mediated tumor ablation. Smart and multifunctional types of CS nanoparticles, including pH-, light- and redox-responsive nanoparticles, can be used to improve the potential for breast cancer removal. In addition, the acceleration of immunotherapy by CS nanoparticles has also been achieved, and there is potential to develop CS-nanoparticle hydrogels that can be used to suppress tumorigenesis.

Hydrogels dressings based on guar gum and chitosan: Inherent action against resistant bacteria and fast wound closure

Hydrogels made with depolymerized guar gum, oxidized with theoretical oxidation degrees of 20, 35 and 50 %, were obtained via Schiff's base reaction with N-succinyl chitosan. The materials obtained were subjected to characterization by FT-IR, rheology, swelling, degradation, and morphology. Additionally, their gelation time categorized all three hydrogels as injectable. The materials' swelling degrees in Phosphate-Buffered Saline (PBS) were in the range of 26-35 g of fluid/g gel and their pore size distribution was heterogeneous, with pores varying from 67 to 93 μm. All hydrogels degraded in PBS solution, but maintained around 40 % of their initial mass after 28 days, which was more than enough time for wound healing. The biomaterials were also flexible, self-repairing, adhesive and cytocompatible and presented intrinsic actions, regardless of the presence of additives or antibiotics, against gram-positive (Staphylococcus aureus, Staphylococcus epidermidis) and gram-negative bacteria (Escherichia coli). However, the most pronounced bactericidal effect was against resistant Staphylococcus aureus - MRSA. In vivo assays, performed with 50 % oxidized gum gel, demonstrated that this material exerted anti-inflammatory effects, accelerating the healing process and restoring tissues by approximately 99 % within 14 days. In conclusion, these hydrogels have unique characteristics, making them excellent candidates for wound-healing dressings.

Rapidly in situ forming an injectable Chitosan/PEG hydrogel for intervertebral disc repair

Intervertebral disc (IVD) degeneration occurred with the increasing age or accidents has puzzled peoples in daily life. To seal IVD defect by injectable hydrogels is a promising method for slowing down IVD degeneration. Herein, we reported a rapidly in situ forming injectable chitosan/PEG hydrogel (CSMA-PEGDA-L) through integrating photo-crosslink of methacrylate chitosan (CSMA) with Schiff base reaction between CSMA and aldehyde polyethylene glycol (PEGDA). The CSMA-PEGDA-L possessed a stronger compressive strength than the photo-crosslinked CSMA-L hydrogel and Schiff-base-crosslinked CSMA-PEGDA hydrogel. This chitosan/PEG hydrogel showed low cytotoxicity from incubation experiments of nucleus pulpous cells. When implanted on the punctured IVD of rat's tail, the CSMA-PEGDA-L hydrogel could well retard the progression of IVD degeneration through physical plugging, powerfully proven by radiological and histological evaluations. This work demonstrated the strategy of in situ injectable glue may be a potential solution for prevention of IVD degeneration.

Carboxymethyl Chitosan Microgels for Sustained Delivery of Vancomycin and Long-Lasting Antibacterial Effects

Carboxymethyl chitosan (CMCh) is a unique polysaccharide with functional groups that can develop positive and negative charges due to the abundant numbers of amine and carboxylic acid groups. CMCh is widely used in different areas due to its excellent biocompatibility, biodegradability, water solubility, and chelating ability. CMCh microgels were synthesized in a microemulsion environment using divinyl sulfone (DVS) as a crosslinking agent. CMCh microgel with tailored size and zeta potential values were obtained in a single stem by crosslinking CMCh in a water-in-oil environment. The spherical microgel structure is confirmed by SEM analysis. The sizes of CMCh microgels varied from one micrometer to tens of micrometers. The isoelectric point of CMCh microgels was determined as pH 4.4. Biocompatibility of CMCh microgels was verified on L929 fibroblasts with 96.5 ± 1.5% cell viability at 1 mg/mL concentration. The drug-carrying abilities of CMCh microgels were evaluated by loading Vancomycin (Van) antibiotic as a model drug. Furthermore, the antibacterial activity efficiency of Van-loaded CMCh microgels (Van@CMCh) was investigated. The MIC values of the released drug from Van@CMCh microgels were found to be 68.6 and 7.95 µg/mL against E. coli and S. aureus, respectively, at 24 h contact time. Disk diffusion tests confirmed that Van@CMCh microgels, especially for Gram-positive (S. aureus) bacteria, revealed long-lasting inhibitory effects on bacteria growth up to 72 h.

Golden Buckwheat Extract-Loaded Injectable Hydrogel for Efficient Postsurgical Prevention of Local Tumor Recurrence Caused by Residual Tumor Cells

To prevent local tumor recurrence caused by possible residual cancer cells after surgery, avoid toxicity of systemic chemotherapy and protect the fragile immune system of postsurgical patients, an increasing amount of attention has been paid to local anti-cancer drug delivery systems. In this paper, golden buckwheat was first applied to prevent post-operative tumor recurrence, which is a Chinese herb and possesses anti-tumor activity. Golden buckwheat extract-loaded gellan gum injectable hydrogels were fabricated via Ca²⁺ crosslinking for localized chemotherapy. Blank and/or drug-loaded hydrogels were characterized via FT-IR, TG, SEM, density functional theory, drug release and rheology studies to explore the interaction among gellan gum, Ca²⁺ and golden buckwheat extract (GBE). Blank hydrogels were non-toxic to NIH3T3 cells. Of significance, GBE and GBE-loaded hydrogel inhibited the proliferation of tumor cells (up to 90% inhibition rate in HepG2 cells). In vitro hemolysis assay showed that blank hydrogel and GBE-loaded hydrogel had good blood compatibility. When GBE-loaded hydrogel was applied to the incompletely resected tumor of mice bearing B16 tumor xenografts, it showed inhibition of tumor growth in vivo and induced the apoptosis of tumor cells. Taken together, gellan gum injectable hydrogel containing GBE is a potential local anticancer drug delivery system for the prevention of postsurgical tumor recurrence.

Preparation of Ultra-Small Copper Nanoparticles-Loaded Self-Healing Hydrogels with Antibacterial, Inflammation-Suppressing and Angiogenesis-Enhancing Properties for Promoting Diabetic Wound Healing

Background

Bacterial invasion, protracted inflammation, and angiogenesis inhibition are hallmarks of chronic diabetic wounds, bringing about patient morbidity and rising healthcare costs. For such wounds, there are currently few efficient therapies available.

Methods

We reported the development of carboxymethyl chitosan (CMCS)-based self-healing hydrogel loaded with ultra-small copper nanoparticles (Cunps) for local treatment of diabetic wound healing. The structure of Cunps was identified by XRD, TEM, XPS and other methods, and the characterization of the synthesized Cunps-loaded self-healing carboxymethyl chitosan (CMCS)-protocatechualdehyde (PCA) hydrogel (Cunps@CMCS-PCA hydrogel) was further investigated. The therapeutic effect of Cunps@CMCS-PCA hydrogel in diabetic wound healing was explored in vitro and in vivo.

Results

The findings showed that a kind of ultra-small size copper nanoparticles with excellent biocompatibility was prepared. CMCS was chemically conjugated to PCA to form self-healing hydrogels via the formation of an amide bond followed by the loading of ultra-small copper nanoparticles. The obtained Cunps@CMCS-PCA hydrogel showed a typical three-dimensional interlinked network structure with self-healing ability and porosity. It exhibited good biocompatibility in diabetic wounds. Furthermore, Cunps@CMCS-PCA hydrogel group significantly prevented bacterial growth in the skin wound of diabetic rats as compared to model group and CMCS-PCA hydrogel-treated group. After 3 days, no visible bacterial proliferation was observed. It also increased angiogenesis through Cunps mediated activation of ATP7A to prevent induction of autophagy. Furthermore, Cunps@CMCS-PCA hydrogel mainly depended on PCA-induced inhibition on inflammation of macrophage via JAK2/STAT3 signaling pathway. As a result, compared with delayed wound healing process with lower wound healing rate valued at 68.6% within 7 days in the model group, Cunps@CMCS-PCA significantly accelerated wound healing recovery and increased wound healing rate to 86.5%, suggesting that Cunps@CMCS-PCA hydrogel effectively accelerated wound healing.

Conclusion

Cunps@CMCS-PCA hydrogel offered a new therapeutic approach for quickening diabetic wound healing.

Preparation and Properties of Self-Cross-Linking Hydrogels Based on Chitosan Derivatives and Oxidized Sodium Alginate

A self-cross-linking and biocompatible hydrogel has wide application potential in the field of tissue engineering. In this work, an easily available, biodegradable, and resilient hydrogel was prepared using a self-cross-linking method. This hydrogel was composed of N-2-hydroxypropyl trimethyl ammonium chloride chitosan (HACC) and oxidized sodium alginate (OSA). A stable and reversible cross-linking network was formed by the Schiff base self-cross-linked and hydrogen bonding. The addition of a shielding agent (NaCl) may weaken the intense electrostatic effect between HACC and OSA and solve the problem of flocculation caused by the rapid formation of ionic bonds, which provided an extended time for the Schiff base self-cross-linked reaction for forming a homogeneous hydrogel. Interestingly, the shortest time for the formation of the HACC/OSA hydrogel was within 74 s and the hydrogel had a uniform porous structure and enhanced mechanical properties. The HACC/OSA hydrogel withstood large compression deformation due to improved elasticity. What's more, this hydrogel possessed favorable swelling property, biodegradation, and water retention. The HACC/OSA hydrogels have great antibacterial properties against Staphylococcus aureus and Escherichia coli and demonstrated good cytocompatibility as well. The HACC/OSA hydrogels have a good sustained release effect on rhodamine (model drug). Thus, the obtained self-cross-linked HACC/OSA hydrogels in this study have potential applications in the field of biomedical carriers.

Fabrication and evaluation of antimicrobial cellulose/Arabic gum hydrogels as potential drug delivery vehicle

This article aims to assess the highly potent antimicrobial hydrogels composed of cellulose and Arabic gum containing sulfadiazine drug (sulfadiazine-loaded Cel/AG) as drug-targeting carriers. ATR-IR, SEM/ EDS, XRD, and XPS methods were used to investigate the hydrogel. The highest water absorption % was 489.93 ± 4.5 at pH 7.4. Pseudo-second order and Fickian diffusion govern the swelling behavior. The maximal sulfadiazine loading percent was 82.291 ± 74. The in-vitro drug release exhibited significant responses in physiologically simulated pH values. The maximum cumulative release percent was 66.42 ± 0.6 % at pH 7.4. The drug release is predicted by the first order and Korsmeyer-Peppas models. The first diffusion coefficient was (D_i = 9.207 ± 47 × 10^-3 cm²/h) and the late one was (D_L = 5.64 ± 9.0 × 10^-2 cm²/h) at pH 7.4. That hydrogel is well-thought-out a potential drug delivery vehicle. The thermal stability of the Cel/AG hydrogel drug carrier has been enhanced by the incorporation of sulfadiazine which is evidenced by increasing the total activation approximately two-fold. The total activation energy of Cel/AG and sulfadiazine-loaded Cel/AG hydrogels were -0.07362 and -0.2092 J/mol. The sulfadiazine medication's inhibitory effect was markedly enhanced when it was incorporated into the Cel/AG hydrogel films.

Soy Protein Isolate/Genipin-Based Nanoparticles for the Stabilization of Pickering Emulsion to Design Self-Healing Guar Gum-Based Hydrogels

Nowadays, stretchable self-healing hydrogels designed by biomass-based materials have gathered remarkable attention in numerous frontier fields such as wound healing, health monitoring issues, and electronic skin. In this study, soy protein isolate (SPI), a common plant protein, was cross-linked to nanoparticles (SPI NPs) by Genipin, (Gen) which was attracted from the native Geniposide. Oil-in-water (O/W) Pickering emulsion was formed by SPI NPs wrapping the linseed oil, and further implanted into poly(acrylic acid)/guar gum (PAA/GG)-based self-healing hydrogels by multiple reversible weak interactions. With the addition of Pickering emulsion, the hydrogels have achieved a remarkable self-healing ability (self-healing efficiency could reach 91.6% within 10 h) and mechanical properties (tensile strength of 0.89 MPa and strain of 853.2%). Therefore, these hydrogels with good reliable durability have outstanding application prospects in sustainable materials.

Preparation and Characterization of Gluten/SDS/Chitosan Composite Hydrogel Based on Hydrophobic and Electrostatic Interactions

Gluten is a natural byproduct derived from wheat starch, possessing ideal biocompatibility. However, its poor mechanical properties and heterogeneous structure are not suitable for cell adhesion in biomedical applications. To resolve the issues, we prepare novel gluten (G)/sodium lauryl sulfate (SDS)/chitosan (CS) composite hydrogels by electrostatic and hydrophobic interactions. Specifically, gluten is modified by SDS to give it a negatively charged surface, and then it conjugates with positively charged chitosan to form the hydrogel. In addition, the composite formative process, surface morphology, secondary network structure, rheological property, thermal stability, and cytotoxicity are investigated. Moreover, this work demonstrates that the change can occur in surface hydrophobicity caused by the pH-eading influence of hydrogen bonds and polypeptide chains. Meanwhile, the reversible non-covalent bonding in the networks is beneficial to improving the stability of the hydrogels, which shows a prominent prospect in biomedical engineering.

Injectable Self-Healing Adhesive Natural Glycyrrhizic Acid Bioactive Hydrogel for Bacteria-Infected Wound Healing

Bioactive hydrogels self-assembled from naturally occurring herbal small molecules are attracting growing interest for applications in wound healing, due to their versatile intrinsic biological activities, excellent biocompatibility, as well as facile, sustainable, and eco-friendly processes. However, the development of supramolecular herb hydrogels with sufficient strength and multifunctionality as an ideal wound dressing in clinical practice remains a challenge. In this work, inspired by the efficient clinic therapy and directed self-assembly of natural saponin glycyrrhizic acid (GA), we create a novel GA-based hybrid hydrogel to promote full-thickness wound healing and bacterial-infected wound healing. This hydrogel possesses excellent stability and mechanical performance and multifunctional properties, including injectable, shape-adaptation and remodeling, self-healing, and adhesive abilities. This is attributed to the hierarchical dual-network that comprises the self-assembled hydrogen-bond fibrillar network of aldehyde-contained GA (AGA) and the dynamic covalent network through Schiff base reaction between AGA and a biopolymer carboxymethyl chitosan (CMC). Notably, benefiting from the inherent strong biological activity of GA, the AGA-CMC hybrid hydrogel exhibits unique and significant anti-inflammation effects and antibacterial ability, especially toward the Gram-positive Staphylococcus aureus (S. aureus). In vivo experiments demonstrate that the AGA-CMC hydrogel promotes uninfected skin wound healing and S. aureus-infected skin wound healing by enhancing the formation of granulation tissue, facilitating collagen deposition, reducing bacterial infection, and downregulating inflammatory response. This study highlights the design of new and multifunctional bioactive herb hydrogels from natural drug-food homologous small molecules, which can serve as a promising wound-healing dressing for biomedical applications.

Recent advances in carboxymethyl chitosan-based materials for biomedical applications

Chitosan (CS) and its derivatives have been applied extensively in the biomedical field owing to advantageous characteristics including biodegradability, biocompatibility, antibacterial activity and adhesive properties. The low solubility of CS at physiological pH limits its use in systems requiring higher dissolving ability and a suitable drug release rate. Besides, CS can result in fast drug release because of its high swelling degree and rapid water absorption in aqueous media. As a water-soluble derivative of CS, carboxymethyl chitosan (CMC) has certain improved properties, rendering it a more suitable candidate for wound healing, drug delivery and tissue engineering applications. This review will focus on the antibacterial, anticancer and antitumor, antioxidant and antifungal bioactivities of CMC and the most recently described applications of CMC in wound healing, drug delivery, tissue engineering, bioimaging and cosmetics.

pH-sensitive gallol-rich chitosan hydrogel beads for on-off controlled drug delivery

Malignant tumors have emerged as a serious health issue, and the interest in developing pH-sensitive polymers for site-specific drug delivery has increased. The physical and/or chemical properties of pH-sensitive polymers depend on the pH, and thus, drugs can be released by cleaving dynamic covalent and/or noncovalent bonds. In this study, gallic acid (GA) was conjugated to chitosan (CS) to prepare self-crosslinked hydrogel beads containing Schiff base (imine bond) crosslinks. The CS-GA hydrogel beads were formed by the dropwise addition of the CS-GA conjugate solution into a Tris-HCl buffer solution (TBS, pH 8.5). The pH-sensitivity of pristine CS was significantly enhanced following the introduction of GA moiety, and as a result, the CS-GA hydrogel beads swelled more than approximately 5000 % at pH 4.0, indicating an excellent swelling/deswelling ability of the beads at different pH (pH 4.0 and 8.5). The reversible breakage/recovery of the imine crosslinks in the CS-GA hydrogel beads was confirmed through X-ray photoelectron spectroscopic and rheological studies. Finally, Rhodamine B was loaded onto the hydrogel beads as a model drug to investigate the pH-sensitive drug release behavior. At pH 4, the drug was released up to approximately 83 % within 12 h. The findings indicate that the CS-GA hydrogel beads have great potential as a drug delivery system that is sensitive to acidic tumor sites in the body.

A Small Sugar Molecule with Huge Potential in Targeted Cancer Therapy

The number of cancer-related diseases is still growing. Despite the availability of a large number of anticancer drugs, the ideal drug is still being sought that would be effective, selective, and overcome the effect of multidrug resistance. Therefore, researchers are still looking for ways to improve the properties of already-used chemotherapeutics. One of the possibilities is the development of targeted therapies. The use of prodrugs that release the bioactive substance only under the influence of factors characteristic of the tumor microenvironment makes it possible to deliver the drug precisely to the cancer cells. Obtaining such compounds is possible by coupling a therapeutic agent with a ligand targeting receptors, to which the attached ligand shows affinity and is overexpressed in cancer cells. Another way is to encapsulate the drug in a carrier that is stable in physiological conditions and sensitive to conditions of the tumor microenvironment. Such a carrier can be directed by attaching to it a ligand recognized by receptors typical of tumor cells. Sugars seem to be ideal ligands for obtaining prodrugs targeted at receptors overexpressed in cancer cells. They can also be ligands modifying polymers' drug carriers. Furthermore, polysaccharides can act as selective nanocarriers for numerous chemotherapeutics. The proof of this thesis is the huge number of papers devoted to their use for modification or targeted transport of anticancer compounds. In this work, selected examples of broad-defined sugars application for improving the properties of both already-used drugs and substances exhibiting anticancer activity are presented.

Chitosan - dextran phosphate carbamate hydrogels for locally controlled co-delivery of doxorubicin and indomethacin: From computation study to in vivo pharmacokinetics

The development of synergistic drug combinations is a promising strategy for effective cancer suppression. Here, we report all-polysaccharide biodegradable polyelectrolyte complex hydrogels (DPCS) based on dextran phosphate carbamate (DP) and chitosan (CS) for controlled co-delivery of the anticancer drug doxorubicin (DOX) and the non-steroidal anti-inflammatory drug indomethacin (IND). IND can induce more apoptosis in tumor cells by reducing the level of multidrug resistance-associated protein 1. Based on calculations using density functional theory and zeta potential analysis data, carriers with high drug loading were obtained. The release profile of both drugs from the hydrogels was tuned by changing the molecular weight and functional groups content of the polysaccharides. The optimized DPCS showed a steady release of DOX both in vitro and in vivo, and a gradual release of IND, which constantly induced the action of DOX. Considering all of these benefits, DOX- and IND-loaded DPCS offer a promising long-acting polysaccharide-based antitumor platform.

Advances and Progress in Self-Healing Hydrogel and Its Application in Regenerative Medicine

A hydrogel is a three-dimensional structure that holds plenty of water, but brittleness largely limits its application. Self-healing hydrogels, a new type of hydrogel that can be repaired by itself after external damage, have exhibited better fatigue resistance, reusability, hydrophilicity, and responsiveness to environmental stimuli. The past decade has seen rapid progress in self-healing hydrogels. Self-healing hydrogels can automatically self-repair after external damage. Different strategies have been proposed, including dynamic covalent bonds and reversible noncovalent interactions. Compared to traditional hydrogels, self-healing gels have better durability, responsiveness, and plasticity. These features allow the hydrogel to survive in harsh environments or even to be injected as a drug carrier. Here, we summarize the common strategies for designing self-healing hydrogels and their potential applications in clinical practice.

Stimuli-responsive injectable chitosan-based hydrogels for controlled drug delivery systems

In the last decade, injectable hydrogels have attracted a lot of attention due to their excellent functional properties in the field of drug delivery for precise, non-invasive and focused tissue locations. Therefore, designing drug delivery systems (DDS) responsive to hydrogel stimuli to release a drug to an external stimulus with various advantages, can be very challenging. Due to their biocompatibility, mucosal adhesion, and hemostatic activity, chitosan (Chitosan)-based hydrogels offer a lot of potential for tissue engineering and drug delivery. It can be difficult to manage the structure of these stimuli-responsive CS hydrogels or they may require additional crosslinking agents, such as hydrogels with dual pH and thermo-responsiveness. Therefore, it is crucial to create these hydrogels for medicinal applications.

Chitosan-based nanoscale systems for doxorubicin delivery: Exploring biomedical application in cancer therapy

Green chemistry has been a growing multidisciplinary field in recent years showing great promise in biomedical applications, especially for cancer therapy. Chitosan (CS) is an abundant biopolymer derived from chitin and is present in insects and fungi. This polysaccharide has favorable characteristics, including biocompatibility, biodegradability, and ease of modification by enzymes and chemicals. CS-based nanoparticles (CS-NPs) have shown potential in the treatment of cancer and other diseases, affording targeted delivery and overcoming drug resistance. The current review emphasizes on the application of CS-NPs for the delivery of a chemotherapeutic agent, doxorubicin (DOX), in cancer therapy as they promote internalization of DOX in cancer cells and prevent the activity of P-glycoprotein (P-gp) to reverse drug resistance. These nanoarchitectures can provide co-delivery of DOX with antitumor agents such as curcumin and cisplatin to induce synergistic cancer therapy. Furthermore, co-loading of DOX with siRNA, shRNA, and miRNA can suppress tumor progression and provide chemosensitivity. Various nanostructures, including lipid-, carbon-, polymeric- and metal-based nanoparticles, are modifiable with CS for DOX delivery, while functionalization of CS-NPs with ligands such as hyaluronic acid promotes selectivity toward tumor cells and prevents DOX resistance. The CS-NPs demonstrate high encapsulation efficiency and due to protonation of amine groups of CS, pH-sensitive release of DOX can occur. Furthermore, redox- and light-responsive CS-NPs have been prepared for DOX delivery in cancer treatment. Leveraging these characteristics and in view of the biocompatibility of CS-NPs, we expect to soon see significant progress towards clinical translation.