The implications of recent advances in carboxymethyl chitosan based targeted drug delivery and tissue engineering applications

O-carboxymethyl chitosan in biomedicine: A review

O-carboxymethyl chitosan (O-CMC) is a chitosan derivative produced through the substitution of hydroxyl (-OH) functional groups in glucosamine units with carboxymethyl (-CH2COOH) substituents, effectively addressing the inherent solubility issues of chitosan in aqueous solutions. O-CMC has garnered significant interest due to its enhanced solubility, elevated viscosity, minimal toxicity, and advantageous biocompatibility properties. Furthermore, O-CMC demonstrates antibacterial, antifungal, and antioxidant characteristics, rendering it a promising candidate for various biomedical uses such as wound healing, tissue engineering, anti-tumor therapies, biosensors, and bioimaging. Additionally, O-CMC is well-suited for the fabrication of nanoparticles, hydrogels, films, microcapsules, and tablets, offering opportunities for effective drug delivery systems. This review outlines the distinctive features of O-CMC, offers analyses of advancements and future potential based on current research, examines significant obstacles for clinical implementation, and foresees its ongoing significant impacts in the realm of biomedicine.

Carboxymethyl chitosan-methacrylic acid gelatin hydrogel for wound healing and vascular regeneration

At present, wound dressings in clinical applications are primarily used for superficial skin wounds. However, these dressings have significant limitations, including poor biocompatibility and limited ability to promote wound healing. To address the issue, this study used aldehyde polyethylene glycol as the cross-linking agent to design a carboxymethyl chitosan-methacrylic acid gelatin hydrogel with enhanced biocompatibility, which can promote wound healing and angiogenesis. The CSDG hydrogel exhibits acid sensitivity, with a swelling ratio of up to 300%. Additionally, it exhibited excellent resistance to external stress, withstanding pressures of up to 160 kPa and self-deformation of 80%. Compared to commercially available chitosan wound gels, the CSDG hydrogel demonstrates excellent biocompatibility, antibacterial properties, and hemostatic ability. Bothin vitroandin vivoresults showed that the CSDG hydrogel accelerated blood vessel regeneration by upregulating the expression of CD31, IL-6, FGF, and VEGF, thereby promoting rapid healing of wounds. In conclusion, this study successfully prepared the CSDG hydrogel wound dressings, providing a new approach and method for the development of hydrogel dressings based on natural macromolecules.

Chitosan interaction with stomach mucin layer to enhances gastric retention and mucoadhesive properties

The interaction between mucoadhesive materials and mucin layers is of significant interest in the development of drug delivery systems and biomedical applications for effective targeting and prolonged stay in the gastrointestinal tract. In this article, the current advancement and mucoadhesive properties of chitosan concerning the stomach mucin layer and its interactions have been briefly addressed. Chitosan a biocompatible polysaccharide exhibited promising mucoadhesive properties attributed to its cationic nature and ability to establish bonds with mucin glycoproteins. The mucoadhesion mechanism is ascribed to the electrostatic interactions between the positively charged amino (NH2) groups of chitosan and the sialic acid residues in mucin glycoprotein which carry a negative charge. The article provides a succinct overview of prior uses, current trends, and recent advancements in chitosan-based gastric-targeted delivery systems. We look forward to further innovations and emerging research related to chitosan-based methods of delivery that may increase the chitosan suitability for use in novel therapeutic approaches.

Preparation and Characterization of Carboxymethyl Chitosan/Sodium Alginate Composite Hydrogel Scaffolds Carrying Chlorhexidine and Strontium-Doped Hydroxyapatite

Herein, we introduce a novel composite hydrogel scaffold designed for addressing infectious jaw defects, a significant challenge in clinical settings caused by the inherent limited self-regenerative capacity of bone tissues. The scaffold was engineered from a blend of carboxymethyl chitosan (CMCS)/sodium alginate (SA) hydrogel (CSH), β-cyclodextrin/chlorhexidine clathrate (β-CD-CHX), and strontium-nanohydroxyapatite nanoparticles (Sr-nHA). The β-CD-CHX and Sr-nHA components were synthesized using a saturated aqueous solution and a coprecipitation method, respectively. Subsequently, these elements were encapsulated within the CSH matrix. Comprehensive characterization of the CMCS/SA/β-CD-CHX/Sr-nHA composite hydrogel scaffold via scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy validated the successful synthesis. The swelling and in vitro degradation behaviors proved that the composite hydrogel had good physical properties, while in vitro evaluations demonstrated favorable biocompatibility and osteoinductive properties. Additionally, antibacterial assessments revealed its effectiveness against common pathogens, Staphylococcus aureus and Escherichia coli. Overall, our results indicate that the CMCS/SA/β-CD-CHX/Sr-nHA composite hydrogel scaffolds exhibit significant potential for effectively treating infection-prone jaw defects.

Synthesis of carboxymethyl chitosan-guar gum-poly(vinylpyrrolidone) ternary blended hydrogels with antibacterial/anticancer efficacy and drug delivery applications

Biopolymers have the utmost significance in biomedical applications and blending synthetic polymers has shown favorable characteristics versus individual counterparts. The utilization of the blends can be restricted through the use of toxic chemical agents such as initiators or crosslinkers. In this regard, a chemical agent-free ionizing irradiation is a beneficial alternative for preparing the hydrogels for biomedical applications. In this study, carboxymethyl chitosan (CM-CS), guar gum (GG), and poly(vinylpyrrolidone) (PVP) based ternary blends (TB) were crosslinked using various doses of ionizing irradiation to fabricate hydrogels. The prepared hydrogels were characterized for physicochemical properties, swelling analysis, biological assays, and drug delivery applications. Swelling analysis in distilled water revealed that the hydrogels exhibit excellent swelling characteristics. An in vitro cytocompatibility assay showed that the hydrogels have greater than 90% cell viability for the human epithelial cell line and a decreasing cell viability trend for the human alveolar adenocarcinoma cell line. In addition, the prepared hydrogels possessed excellent antibacterial characteristics against gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli). Finally, the release studies of anti-inflammatory Quercus acutissima (QA) loaded hydrogels exhibited more than 80% release in phosphate-buffered saline (pH = 7.4). These findings suggest that TB hydrogels can be used as suitable carrier media for different release systems and biomedical applications.

A Cellulose/Chitosan Dual Cross-Linked Multifunctional and Resilient Hydrogel for Emergent Open Wound Management

Adhesive hydrogel holds huge potential in biomedical applications, such as hemostasis and emergent wound management during outpatient treatment or surgery. However, most adhesive hydrogels underperform to offer robust adhesions on the wet tissue, increasing the risk of hemorrhage and reducing the fault tolerance of surgery. To address this issue, this work develops a polysaccharide-based bioadhesive hydrogel tape (ACAN) consisting of dual cross-linking of allyl cellulose (AC) and carboxymethyl chitosan (CMCS). The hygroscopicity of AC and CMCS networks enables ACAN to remove interfacial water from the tissue surface and initializes a physical cross-link instantly. Subsequently, covalent cross-links are developed with amine moieties to sustain long-term and robust adhesion. The dual cross-linked ACAN also has good cytocompatibility with controllable mechanical properties matching to the tissue, where the addition of CMCS provides remarkable antibacterial properties and hemostatic capability. Moreover, compared with commercially available 3 M film, ACAN provides an ultrafast wound healing on tissue. The ACAN hybrid hydrogels have advantages such as biocompatibility and antibacterial, hemostatic, and wound healing properties, shedding new light on first-aid tape design and advancing the cellulose-based materials technology for high-performance biomedical applications.

Gelatin/O-carboxymethyl chitosan injectable self-healing hydrogels for ibuprofen and naproxen dual release

Recently, a significantly greater clinical benefit has been reported with a combination of glucosamine sulfate and nonsteroidal anti-inflammatory drugs (NSAIDs) compared to either treatment alone for the growing osteoarthritis (OA) disease. So, this study introduces hydrogels using O-carboxymethyl chitosan (O-CMC, structurally akin glucosamine glycan), and Gelatin type A (GA) in a 1:2 ratio with β-glycerophosphate (βGPh) at varying percentages (5 %, 12.5 %, and 15 %). We show that hydrogel properties, adaptable for drug delivery or tissue engineering, can be fine-tuned based on OCMC:βGPh ratio. CMC/GA/βGPh-12.5 exhibited a swelling rate of 189 %, compressive stress of 164 kPa, and compressive modulus of 3.4 kPa. The self-healing hydrogel also exhibited excellent injectability through a 21-gauge needle, requiring only 5 N of force. Ibuprofen and Naproxen release from CMC/GA/βGPh-12.5 and CMC/GA/βGPh-15 of designed dimensions (bi-layer structures of different diameter and height) were measured, and drug release kinetics were estimated using mathematical equations (MATLAB and polyfit program). CMC/GA/βGPh-12.5 demonstrated significant antibacterial effects against E. coli and S. aureus, a high cell survival rate of 89 % against L929 fibroblasts, and strong cell adhesion, all indicating biocompatibility. These findings underscore potential of these hydrogels as promising candidates for treating inflammatory diseases such as osteoarthritis.

Curcumin-loaded pH-sensitive carboxymethyl chitosan nanoparticles for the treatment of liver cancer

In this study, the pH-responsive API-CMCS-SA (ACS) polymeric nanoparticles (NPs) based on 1-(3-amino-propyl) imidazole (API), stearic acid (SA), and carboxymethyl chitosan (CMCS) were fabricated for the effective transport of curcumin (CUR) in liver cancer. CUR-ACS-NPs with various degrees of substitution (DS) were employed to prepare through ultrasonic dispersion method. The effect of different DS on NPs formation was discussed. The obtained CUR-ACS-NPs (DSSA=12.4%) had high encapsulation rate (more than 85%) and uniform particle size (186.2 ± 1.42 nm). The CUR-ACS-NPs showed better stability than the other groups. Drug release from the CUR-ACS-NPs was pH-dependent, and more than 90% or 65% of CUR was released in 48 h in weakly acid medium (pH 5.0 or 6.0, respectively). Additionally, the CUR-ACS-NPs increased the intracellular accumulation of CUR and demonstrated high anticancer effect on HepG2 cells compared with the other groups. CUR-ACS-NPs prolonged the retention time of the drug, and the area under the curve (AUC) increased significantly in vivo. The in vivo antitumor study further revealed that the CUR-ACS-NPs exhibited the capability of inhibiting tumor growth and lower systemic toxicity. Meanwhile, CUR, CUR-CS-NPs, and CUR-ACS-NPs could be detected in the evaluated organs, including tumor, liver, spleen, lung, heart, and kidney in distribution studies. Among them, CUR-ACS-NPs reached the maximum concentration at the tumor site, indicating the tumor-targeting properties. In short, the results suggested that CUR-ACS-NPs could act a prospective drug transport system for effective delivery of CUR in cancer treatment.

Injecting hope: chitosan hydrogels as bone regeneration innovators

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

Triple-Hybrid BioScaffold Based on Silk Fibroin, Chitosan, and nano-Biphasic Calcium Phosphates: Preparation, Characterization of Physiochemical and Biopharmaceutical Properties

Bioscaffolds, which promote cell regeneration and restore tissues' functions, have emerged as significant need in clinic. The hybrid of several biomaterials in a bioscaffold renders clinically advanced and relevant properties for applications yet add challenges in cost efficiency, production, and clinical investigation. This study proposes a facile and sustainable method to formulate a triple-hybrid bioscaffold based on Vietnamese cocoon origin Silk Fibroin, Chitosan, and nano-Biphasic Calcium Phosphates (nano-BCP) that can be easily molded, has high porosity (55-80%), and swelling capacity that facilitates cell proliferation and nutrient diffusion. Notably, their mechanical properties, in particular compressive strength, can easily be tuned in a range from 50 - 200 kPa by changing the amount of nano-BCP addition, which is comparable to the successful precedents for productive cell regeneration. The latter parts investigate the biopharmaceutical properties of a representative bioscaffold, including drug loading and release studies with two kinds of active compounds, salmon calcitonin and methylprednisolone. Furthermore, the bioscaffold is highly biocompatible as the results of hemocompatibility and hemostasis tests, as well as ovo chick chorioallantoic membrane investigation. The findings of the study suggest the triple-hybrid scaffold as a promising platform for multi-functional drug delivery and bone defect repair.

A Novel Zn(II) Coordination Polymer: Fluorescence Performances, Molecular Docking and Loaded with Bleomycin-Hydrogels on Hemangiomas

In this study, we successfully synthesized an innovative 1D-Zn(II) coordination polymer, denoted as [Zn(L)(H2O)2]n, employing the Schiff base {4-[(2-hydroxy-3-methoxy-benzylidene)-amino]-benzoic acid} (H2L). The Schiff base was obtained through the reaction of 4-aminobenzoic acid and o-vanillin under slow volatilization conditions. The resulting compound exhibits remarkable green fluorescence emission properties, indicating its potential as a novel fluorescent and sensing material. Hydrogels based on hyaluronic acid (HA) and carboxymethyl chitosan (CMCS), denoted as HA/CMCS hydrogels, were synthesized using a chemical method. Additionally, we utilized bleomycin as a model drug to synthesize a novel bleomycin metal gel and assessed its anti-hemangioma activity. Molecular docking simulations revealed that the Zn complex can form stable bonds with the key target, involving the methoxy and carboxyl groups on the Zn complex.

Hydrogel-Based Skin Regeneration

The skin is subject to damage from the surrounding environment. The repair of skin wounds can be very challenging due to several factors such as severe injuries, concomitant infections, or comorbidities such as diabetes. Different drugs and wound dressings have been used to treat skin wounds. Tissue engineering, a novel therapeutic approach, revolutionized the treatment and regeneration of challenging tissue damage. This field includes the use of synthetic and natural biomaterials that support the growth of tissues or organs outside the body. Accordingly, the demand for polymer-based therapeutic strategies for skin tissue defects is significantly increasing. Among the various 3D scaffolds used in tissue engineering, hydrogel scaffolds have gained special significance due to their unique properties such as natural mimicry of the extracellular matrix (ECM), moisture retention, porosity, biocompatibility, biodegradability, and biocompatibility properties. First, this article delineates the process of wound healing and conventional methods of treating wounds. It then presents an examination of the structure and manufacturing methods of hydrogels, followed by an analysis of their crucial characteristics in healing skin wounds and the most recent advancements in using hydrogel dressings for this purpose. Finally, it discusses the potential future advancements in hydrogel materials within the realm of wound healing.

In Situ Formation of Hydrogel Wound Dressing Based on Carboxymethyl Chitin/Tannic Acid for Promoting Skin Wound Healing

Triggering the healing process of drug-resistant bacteria-infected wounds has attracted great attention due to global morbidity that may induce gangrene, amputation, and even death. Here, a chitin derivative, carboxymethyl chitosan (CMC), tannic acid (TA), and Cu2+ were used for hydrogel engineering. Using sodium bicarbonate as the neutralizer and reductant, hydrogen bonds between CMC and TA and in situ Cu(OH)2 generation via ion coordination force between Cu2+ and TA facilitated the synthesis of CMC/TA/Cu hydrogel. Cu2+ and TA release, cytotoxicity, in vitro cell migration, angiogenesis, and antidrug-resistant bacteria were measured. Besides, wound closure was evaluated in vivo using the methicillin-resistant Staphylococcus aureus (MRSA)-infected excisional dermal wound mouse model. Negligible toxicity was observed both in vitro and in vivo. Dermal cell migration and angiogenesis were significantly enhanced. In vivo, the CMC/TA/Cu hydrogel induced effective re-epithelialization, collagen deposition, inflammatory alleviation, and MRSA inhibition during wound repair in mice. All these results confirmed that the CMC/TA/Cu hydrogel is a promising novel dressing for chronic wound healing in clinic.

Review: chitosan-based biopolymers for anion-exchange membrane fuel cell application

Chitosan (CS)-based anion exchange membranes (AEMs) have gained significant attention in fuel cell applications owing to their numerous benefits, such as environmental friendliness, flexibility for structural alteration, and improved mechanical, thermal and chemical durability. This study aims to enhance the cell performance of CS-based AEMs by addressing key factors including mechanical stability, ionic conductivity, water absorption and expansion rate. While previous reviews have predominantly focused on CS as a proton-conducting membrane, the present mini-review highlights the advancements of CS-based AEMs. Furthermore, the study investigates the stability of cationic head groups grafted to CS through simulations. Understanding the chemical properties of CS, including the behaviour of grafted head groups, provides valuable insights into the membrane's overall stability and performance. Additionally, the study mentions the potential of modern cellulose membranes for alkaline environments as promising biopolymers. While the primary focus is on CS-based AEMs, the inclusion of cellulose membranes underscores the broader exploration of biopolymer materials for fuel cell applications.

Effect of Chitosan on the Number of Streptococcus mutans in Saliva: A Meta-Analysis and Systematic Review

We conducted a meta-analysis and systematic review to investigate the efficacy of chitosan-containing chewing gums, and to test their inhibitory effects on Streptococcus mutans. The systematic search was performed in three databases (Cochrane Library, EMBASE, and PubMed) and included English-language randomized-controlled trials to compare the efficacy of chitosan in reducing the number of S. mutans. To assess the certainty of evidence, the GRADE tool was used. Mean differences were calculated with a 95% confidence interval for one outcome: bacterial counts in CFU/mL. The protocol of the study was registered on PROSPERO, registration number CRD42022365006. Articles were downloaded (n = 6758) from EMBASE (n = 2255), PubMed (n = 1516), and Cochrane (n = 2987). After the selection process, a total of four articles were included in the qualitative synthesis and three in the quantitative synthesis. Our results show that chitosan reduced the number of bacteria. The difference in mean quantity was -4.68 × 105. The interval of the random-effects model was [-2.15 × 106; 1.21 × 106] and the prediction interval was [1.03 × 107; 9.40 × 106]. The I2 value was 98% (p = 0.35), which indicates a high degree of heterogeneity. Chitosan has some antibacterial effects when used as a component of chewing gum, but further studies are needed. It can be a promising antimicrobial agent for prevention.

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.

Polysaccharide-based (kappa carrageenan/carboxymethyl chitosan) nanofibrous membrane loaded with antifibrinolytic drug for rapid hemostasis- in vitro and in vivo evaluation

This work aimed to establish a novel membrane consisting of hemostatic polysaccharides, kappa-carrageenan (KC), and carboxymethyl chitosan (CMC) in tandem with polyvinyl alcohol that spun together as a matrix and loaded with tranexamic acid (TXA) as antifibrinolytic agent for further coagulation effect during and after oral surgeries. The electrospinning of KC was done for the first time and in comparison of CMC has better hemostatic efficacy. The effect of the hemostat was investigated by its surface morphology (SEM), FTIR/ATR analysis, swelling behavior in both PBS and blood, hydrophilicity, porosity, mechanical properties, and cumulative release rate. The effect of materials and the drug concentration ratio were considered. The effect of acetic acid percent in aqueous solutions of CMC/PVA and KC/PVA on morphology was investigated. The cell culture assay showed that all membranes interacted well (98 %) with fibroblast cells attached and grown on the fabricated substrate. Furthermore, the membranes are evaluated by clotting time, whole blood clotting, hemocompatibility, and platelet and RBC adhesion tests. Also, the hemostatic performance of the membrane was analyzed in vivo, using the tail and liver bleeding model in rats. Therefore, TXA loading into CMC and KC dressing could be an attractive hemostatic system for various clinical applications.

Arginase from Priestia megaterium and the Effects of CMCS Conjugation on Its Enzymological Properties

Arginase has shown promising potential in treating cancers by arginine deprivation therapy; however, low enzymatic activity and stability of arginase are impeding its development. This study was aimed to improve the enzymological properties of a marine bacterial arginase by carboxymethyl chitosan (CMCS) conjugation. An arginase producing marine bacterium Priestia megaterium strain P6 was isolated and identified. The novel arginase PMA from the strain was heterologously expressed, purified, and then conjugated to CMCS by ionic gelation with calcium chloride as the crosslinking agent. Enzymological properties of both PMA and CMCS-PMA conjugate were determined. The optimum temperature for PMA and CMCS-PMA at pH 7 were 60 °C and 55 °C, respectively. The optimum pH for PMA and CMCS-PMA at 37 °C were pH 10 and 9, respectively. CMCS-PMA showed higher thermostability than PMA over 55-70 °C and higher pH stability over pH 4-11 with the highest pH stability at pH 7. At 37 °C and pH of 7, i.e., around the human blood temperature and pH, CMCS-PMA was higher than the free PMA in enzymatic activity and stability by 24% and 21%, respectively. CMCS conjugation not only changed the optimum temperature, optimum pH, and enzymatic activity of PMA, but also improved its pH stability and temperature stability, and thus made it more favorable for medical application.

GE11-modified carboxymethyl chitosan micelles to deliver DOX·PD-L1 siRNA complex for combination of ICD and immune escape inhibition against tumor

Programmed cell death-ligand 1 (PD-L1) small interfering RNA (siRNA) achieves tumor immunotherapy by restoring the immune response of T cells, but the efficacy of PD-1/PD-L1 monotherapy is relatively low. While immunogenic cell death (ICD) can improve the response of most tumors to anti-PD-L1 and enhance tumor immunotherapy. Herein, a targeting peptide GE11-functionalized dual-responsive carboxymethyl chitosan (CMCS) micelle (G-CMssOA) is developed for simultaneous delivery of PD-L1 siRNA and doxorubicin (DOX) in a complex form of DOX·PD-L1 siRNA (D&P). The complex-loaded micelles (G-CMssOA/D&P) have good physiological stability and pH/reduction responsiveness, and improve the intratumoral infiltration of CD4⁺ and CD8⁺ T cells, reduce Tregs (TGF-β), and increase the secretion of immune-stimulatory cytokine (TNF-α). The combination of DOX-induced ICD and PD-L1 siRNA-mediated immune escape inhibition significantly improves anti-tumor immune response and inhibits tumor growth. This complex delivery strategy provides a new approach for effectively delivering siRNA and enhancing anti-tumor immunotherapy.

Carboxymethyl cellulose/sulfur-functionalized Ti-based MOF composite: synthesis, characterization, antimicrobial, antiviral and anticancer potentiality

Microbial resistance is the first morbidity and mortality cause for patients as usually a secondary infection. Additionally, the MOF is a promising material that shows a nice activity in this field. However, these materials need a good formulation to enhance biocompatibility and sustainability. Cellulose and its derivatives are well as filers for this gap. In this presented work, a novel green active system based on carboxymethyl cellulose and Ti-MOF (MIL-125-NH₂@CMC) modified with thiophene (Thio@MIL-125-NH₂@CMC) was prepared by a post-synthetic modification (PSM) route based. FTIR, SEM and PXRD were utilized to characterize nanocomposites. In addition, transmission electron microscopy (TEM) was used to corroborate the nanocomposites' particle size and diffraction pattern as well as the DLS affirmed the size as 50 and 35 nm for MIL-125-NH₂@CMC and Thio@MIL-125-NH₂@CMC, respectively. The formulation of the nanocomposites was validated by physicochemical characterization techniques, while morphological analysis confirmed the nanoform of the prepared composites. The antimicrobial, antiviral and antitumor properties of MIL-125-NH₂@CMC and Thio@MIL-125-NH₂@CMC were assessed. Antimicrobial testing revealed that Thio@MIL-125-NH₂@CMC possesses greater antimicrobial activity than MIL-125-NH₂@CMC. Additionally, Thio@MIL-125-NH₂@CMC demonstrated promising antifungal activity against C. albicans and A. niger where MICs were 31.25 and 0.97 µg/mL, respectively. Also, Thio@MIL-125-NH₂@CMC exhibited antibacterial activity against E. coli and S. aureus where MICs were 1000 and 250 µg/mL, respectively. In addition, the results demonstrated that Thio@MIL-125-NH₂@CMC displayed promising antiviral activity against both HSV1 and COX B4, with antiviral activities of 68.89% and 39.60%, respectively. Furthermore, Thio@MIL-125-NH₂@CMC exhibited potential anticancer activity against MCF7 and PC3 cancerous cell lines, where IC₅₀ was 93.16 and 88.45%, respectively. In conclusion, carboxymethyl cellulose/sulfur-functionalized Ti-based MOF composite was successfully synthesized which had antimicrobial, antiviral and anticancer activities.

Doxorubicin-Loaded Fungal-Carboxymethyl Chitosan Functionalized Polydopamine Nanoparticles for Photothermal Cancer Therapy

In this work, we synthesized doxorubicin-loaded fungal-carboxymethyl chitosan (FC) functionalized polydopamine (Dox@FCPDA) nanoparticles for improved anticancer activity via photothermal drug release. The photothermal properties revealed that the FCPDA nanoparticles with a concentration of 400 µg/mL produced a temperature of about 61.1 °C at 2 W/cm² laser illumination, which is more beneficial for cancer cells. Due to the hydrophilic FC biopolymer, the Dox was successfully encapsulated into FCPDA nanoparticles via electrostatic interactions and pi-pi stacking. The maximum drug loading and encapsulation efficiency were calculated to be 19.3% and 80.2%, respectively. The Dox@FCPDA nanoparticles exhibited improved anticancer activity on HePG2 cancer cells when exposed to an NIR laser (800 nm, 2 W/cm²). Furthermore, the Dox@FCPDA nanoparticles also improved cellular uptake with HepG2 cells. Therefore, functionalizing FC biopolymer with PDA nanoparticles is more beneficial for drug and photothermal dual therapeutic properties for cancer therapy.

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.

Curcumin-Loaded Chitosan Nanoparticle Preparation and Its Protective Effect on Celecoxib-induced Toxicity in Rat isolated Cardiomyocytes and Mitochondria

Curcumin has a wide range of pharmacological activities, including antioxidant, anti-inflammatory and tissue protective. In here we hypothesized that curcumin-loaded chitosan-coated solid lipid nanoparticles (CuCsSLN) are able to increase its overall bioavailability and hence its antioxidant and mitochondria;/lysosomal protective properties of curcumin. CuCsSLN were prepared using solvent diffusion technique for formation of solid lipid nanoparticles (SLNs) and electrostatic coating of positive-charged chitosan to negative surface of SLNs. CuCsSLN showed the encapsulation efficiency of 91.4±2.7%, the mean particle size of 208±9 nm, the polydispersity index of 0.34±0.07, and the zeta potential of+53.5±3.7 mV. The scanning electron microscope (SEM) images of nanoparticles verified their nanometric size and also spherical shape. Curcumin was released from CuCsSLN in a sustain release pattern up to 24 hours. Then isolated cardiomyocytes and mitochondria were simultaneously treated with (1) control (0.05% ethanol), (2) celecoxib (20 µg/ml) treatment, (3) celecoxib (20 µg/ml)+++CuCsSLN (1 µg/ml) treatment, (4) CuCsSLN (1 µg/ml) treatment, (5) celecoxib (20 µg/ml)+++curcumin (10 µM) treatment and (6) curcumin (10 µM) treatment for 4 h at 37°C. The results showed that celecoxib (20 µg/ml) induced a significant increase in cytotoxicity, reactive oxygen species (ROS) formation, mitochondria membrane potential (ΔΨm) collapse, lipid peroxidation, oxidative stress and mitochondrial swelling while CuCsSLN and curcumin reverted the above toxic effect of celecoxib. Our data indicated that the effect of CuCsSLN in a number of experiments, is significantly better than that of curcumin which shows the role of chitosan nanoparticles in increasing effect of curcumin.

Two Hawks with One Arrow: A Review on Bifunctional Scaffolds for Photothermal Therapy and Bone Regeneration

Despite the significant improvement in the survival rate of cancer patients, the total cure of bone cancer is still a knotty clinical challenge. Traditional surgical resectionof bone tumors is less than satisfactory, which inevitably results in bone defects and the inevitable residual tumor cells. For the purpose of realizing minimal invasiveness and local curative effects, photothermal therapy (PTT) under the irradiation of near-infrared light has made extensive progress in ablating tumors, and various photothermal therapeutic agents (PTAs) for the treatment of bone tumors have thus been reported in the past few years, has and have tended to focus on osteogenic bio-scaffolds modified with PTAs in order to break through the limitation that PTT lacks, osteogenic capacity. These so-called bifunctional scaffolds simultaneously ablate bone tumors and generate new tissues at the bone defects. This review summarizes the recent application progress of various bifunctional scaffolds and puts forward some practical constraints and future perspectives on bifunctional scaffolds for tumor therapy and bone regeneration: two hawks with one arrow.

Carboxymethyl Chitosan/Tannic Acid Hydrogel with Antibacterial, Hemostasis, and Antioxidant Properties Promoting Skin Wound Repair

Local causes of slow wound healing include infection and wound hemorrhage. Using sodium bicarbonate as a neutralizer, a variety of carboxymethyl chitosan-tannic acid (CMC-TA) composite hydrogels solidify through hydrogen bonding in this study. The best-performing hydrogel was synthesized by altering the concentration of TA and exhibited remarkable mechanical properties and biocompatibility. Following in vitro characterization tests, the CMC-TA hydrogel exhibited remarkable antibacterial and antioxidant properties, as well as quick hemostasis capabilities. In the in vivo wound healing study, the results showed that the CMC-TA hydrogel could relieve inflammation and promote the recovery of skin incision, re-epithelialization, and collagen deposition. Overall, this multifunctional hydrogel could be an ideal wound dressing for the clinical therapy of full-thickness wounds.

Knowledge mapping concerning applications of nanocomposite hydrogels for drug delivery: A bibliometric and visualized study (2003-2022)

Background: Nanocomposite Hydrogels (NHs) are 3D molecular networks formed by physically or covalently crosslinking polymer with nanoparticles or nanostructures, which are particularly suitable for serving as carriers for drug delivery systems. Many articles pertaining to the applications of Nanocomposite Hydrogels for drug delivery have been published, however, the use of bibliometric and visualized analysis in this area remains unstudied. The purpose of this bibliometric study intended to comprehensively analyze the knowledge domain, research hotspots and frontiers associated with the applications of Nanocomposite Hydrogels for drug delivery. Methods: We identified and retrieved the publications concerning the applications of NHs for drug delivery between 2003 and 2022 from Web of Science Core Collection Bibliometric and visualized analysis was utilized in this investigative study. Results: 631 articles meeting the inclusion criteria were identified and retrieved from WoSCC. Among those, 2,233 authors worldwide contributed in the studies, accompanied by an average annual article increase of 24.67%. The articles were co-authored by 764 institutions from 52 countries/regions, and China published the most, followed by Iran and the United States. Five institutions published more than 40 papers, namely Univ Tabriz (n = 79), Tabriz Univ Med Sci (n = 70), Islamic Azad Univ (n = 49), Payame Noor Univ (n = 42) and Texas A&M Univ (n = 41). The articles were published in 198 journals, among which the International Journal of Biological Macromolecules (n = 53) published the most articles, followed by Carbohydrate Polymers (n = 24) and ACS Applied Materials and Interfaces (n = 22). The top three journals most locally cited were Carbohydrate Polymers, Biomaterials and Advanced materials. The most productive author was Namazi H (29 articles), followed by Bardajee G (15 articles) and Zhang J (11 articles) and the researchers who worked closely with other ones usually published more papers. "Doxorubicin," "antibacterial" and "responsive hydrogels" represent the current research hotspots in this field and "cancer therapy" was a rising research topic in recent years. "(cancer) therapeutics" and "bioadhesive" represent the current research frontiers. Conclusion: This bibliometric and visualized analysis offered an investigative study and comprehensive understanding of publications regarding the applications of Nanocomposite Hydrogels for drug delivery from 2003 to 2022. The outcome of this study would provide insights for researchers in the field of Nanocomposite Hydrogels applications for drug delivery.

Spatiotemporal Regulation of the Bone Immune Microenvironment via Dam-Like Biphasic Bionic Periosteum for Bone Regeneration

The bone immune microenvironment (BIM) regulates bone regeneration and affects the prognosis of fractures. However, there is currently no effective strategy that can precisely modulate macrophage polarization to improve BIM for bone regeneration. Herein, a hybridized biphasic bionic periosteum, inspired by the BIM and functional structure of the natural periosteum, is presented. The gel phase is composed of genipin-crosslinked carboxymethyl chitosan and collagen self-assembled hybrid hydrogels, which act as the "dam" to intercept IL-4 released during the initial burst from the bionic periosteum fiber phase, thus maintaining the moderate inflammatory response of M1 macrophages for mesenchymal stem cell recruitment and vascular sprouting at the acute fracture. With the degradation of the gel phase, released IL-4 cooperates with collagen to promote the polarization towards M2 macrophages, which reconfigure the local microenvironment by secreting PDGF-BB and BMP-2 to improve vascular maturation and osteogenesis twofold. In rat cranial defect models, the controlled regulation of the BIM is validated with the temporal transition of the inflammatory/anti-inflammatory process to achieve faster and better bone defect repair. This strategy provides a drug delivery system that constructs a coordinated BIM, so as to break through the predicament of the contradiction between immune response and bone tissue regeneration.

Statistical optimization of voriconazole nanoparticles loaded carboxymethyl chitosan-poloxamer based in situ gel for ocular delivery: In vitro, ex vivo, and toxicity assessment

The research study reflects the development of novel voriconazole (VCZ) loaded nanoparticles (NPs) for prolonged delivery for the management of ocular diseases. The in situ ophthalmic gel was prepared by incorporating NPs into carboxymethyl chitosan (CMCh) and poloxamer. The central composite design was used to optimize the process for the preparation of nanoparticles by the o/w solvent evaporation method. The developed nanoparticles were evaluated for the encapsulation efficiency (89.6 ± 1.2%), particle size (219.3 ± 1.8 nm), polydispersity index (PDI, 0.1), zeta potential (- 21.1 ± 1.12 mV), saturation solubility, DSC study, and drug release. The etherification process grafts carboxyl surface functional groups, on chitosan, and was confirmed by FTIR and NMR studies. The developed CMCh-poloxamer based gelling system was found to be clear and transparent with gelation temperature varying from 33 to 40 °C. The nanoparticle-loaded gel containing CMCh demonstrated enhanced antifungal activity against Candida albicans. The optimized batch containing CMCh showed improved mucoadhesion by 2.86-fold compared to VCZ nanosuspension. The drug release was prolonged up to 8 h with an ex vivo study suggesting the enhanced permeation across goat cornea estimated via fluorescent microscope. The hen's egg chorioallantoic membrane study revealed that the formulation was non-irritant and tolerated by the chorioallantoic membrane. The present study concludes that the VCZ loaded nanoparticulate in situ ophthalmic gel using CMCh may act as a potential alternative for traditional eye drops.

Characterization of a novel marine microbial uricase from Priestia flexa and evaluation of the effects of CMCS conjugation on its enzymatic properties

A novel uricase producing marine bacterium Priestia flexa alkaAU was isolated and identified. The 16S rDNA and the uricase coding gene were sequenced, analyzed and submitted to GenBank. The uricase from Priestia flexa alkaAU (PFU) was purified, determined to be 58.87 kDa, and conjugated with carboxymethyl chitosan (CMCS) by ionic gelation. CMCS conjugation had no effect on the optimum pH of PFU but decreased the optimum temperature by 10 °C. CMCS conjugation increased the specific activity of PFU by 53% at the human body temperature (37 °C) and small intestine's pH (pH 6.8). Uricase thermostabilizing ability of CMCS was significant in the range of 37-80 °C but not at lower temperatures. For improvement of the pH stability of PFU, CMCS was more effective at pHs 3-5 than pHs 6-11. CMCS increased the half-life of PFU against artificial intestinal fluid by 1.5 folds, which demonstrated the potential capability of CMCS-PFU for oral administration.

L-Cysteine Modified Chitosan Nanoparticles and Carbon-Based Nanostructures for the Intranasal Delivery of Galantamine

The present study evaluates the use of thiolized chitosan conjugates (CS) in combination with two fundamental carbon nanoforms (carbon dots (CDs) and Hierarchical Porous Carbons (HPC)) for the preparation of intranasally (IN) administrated galantamine (GAL) nanoparticles (NPs). Initially, the modification of CS with L-cysteine (Cys) was performed, and the successful formation of a Cys-CS conjugates was verified via ¹H-NMR, FTIR, and pXRD. The new Cys-CS conjugate showed a significant solubility enhancement in neutral and alkaline pH, improving CS’s utility as a matrix-carrier for IN drug administration. In a further step, drug-loaded NPs were prepared via solid-oil–water double emulsification, and thoroughly analyzed by SEM, DLS, FTIR and pXRD. The results showed the formation of spherical NPs with a smooth surface, while the drug was amorphously dispersed within most of the prepared NPs, with the exemption of those systems contianing the CDs. Finally, in vitro dissolution release studies revealed that the prepared NPs could prolong GAL’s release for up to 12 days. In sum, regarding the most promising system, the results of the present study clearly suggest that the preparation of NPs using both Cys-CS and CDs results in a more thermodynamically stable drug dispersion, while a zero-order release profile was achieved, which is essential to attain a stable in vivo pharmacokinetic behavior.

Pharmaceutical and drug delivery applications of chitosan biopolymer and its modified nanocomposite: A review

Due to their improved structural and functional properties as well as biocompatibility, biodegradability, and nontoxicity, chitosan and its nanoparticles are currently grasping the interest of researchers. Although numerous attempts have been made to apply chitosan and its derivatives to biological applications, few have reported in achieving its pharmacological and drug delivery. The goal of the current work is to provide a summary of the chitosan biopolymer's physical, chemical, and biological properties as well as its synthesis of nanoparticles and characterization of its modified nanocomposites. The drug delivery method and pharmaceutical applications of chitosan biopolymer and its modified nanocomposites are examined in further detail in this research. We will introduce also about the most current publications in this field of study as well as its recent expansion.

Recent advances in functionally modified polymers for mucoadhesive drug delivery

Novel methods for the delivery of drugs other than the conventional method of oral administration have been a thrust area of research for a few decades. Mucoadhesive delivery of drugs opened up a new domain where rapid and patient-friendly delivery of drugs can be achieved. Delivery of drugs through the mucosal sites such as buccal, nasal, ocular, sublingual, rectal and vaginal facilitates bypassing the first-pass metabolism and the drug reaches the systemic circulation directly. This helps to increase the bioavailability of the drug. The study of the chemical characteristics of polymers with mucoadhesive properties and how the molecules or the pharmaceuticals are transported across the mucosa is very much needed for the advancement of research in this field. And at the same time, it is very pertinent to know about the anatomy and the physiology of the mucosal tissue and its variation in different regions of the body. In this review, we try to present a comprehensive understanding of relevant topics of mucoadhesion giving more emphasis on the mechanism of transport of drugs across mucosa, and different possible functional modifications of polymers to enhance the property of mucoadhesion.

Enhanced Development of Sweat Latent Fingerprints Based on Ag-Loaded CMCS/PVA Composite Hydrogel Film by Electron Beam Radiation

Over time, difficulties have been encountered in detecting potential fingerprints. In this study, an Ag/CMCS/PVA(ACP) hydrogel film was developed for fingerprint development by electron beam radiation method. The chemical bond, thermostability, chemical components, microstructure, and micromorphology of the CMCS/PVA composite hydrogel film were characterized by FT-IR, TG, XRD, and SEM, respectively. Swelling behaviors and mechanical performance of the CMCS/PVA composite hydrogel were also investigated at different irradiation doses, pH, media, and NaCl contents to obtain the optimum preparation conditions. Through experimental exploration, we found that the fingerprints appeared more obvious when the irradiated prepared ACP hydrogel film was sprayed with 0.6 mg/mL of Ag+ and the excitation wavelength was about 254 nm with UV lamp irradiation for 20 min. The cytotoxicity the CMCS/PVA composite hydrogel on mouse skin fibroblasts L929 cells was also studied, confirming its biological security. Sweat latent fingerprint manifestation has important scientific significance with respect to the development of new processes and functional materials in the field of fingerprint manifestation, enriching and complementing the application of composite hydrogels.

Promotion Effect of Carboxymethyl Chitosan on Dental Caries via Intrafibrillar Mineralization of Collagen and Dentin Remineralization

Objective: To observe ultrastructural changes during the process of carboxymethyl chitosan (CMC)-mediated intrafibrillar mineralization, we evaluated the biomimetic remineralization potential of CMC in type-I collagen fibrils and membranes, and further explored the bond strength as well as the bond interfacial integrity of the biomimetic remineralized artificial caries-affected dentin (ACAD). Methods: A mineralized solution containing 200 μg/mL CMC was used to induce type-I collagen biomimetic remineralization in ACAD, while traditional mineralization without CMC was used as a control. The process and pattern of mineralization were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) as well as structured illumination microscopy (SIM). The Vickers hardness test was used to quantify the dentin hardness, while the microtensile bond strength (µTBS) test was used to assess the bond strength and durability. The bond interfacial integrity was evaluated by a confocal laser scanning microscope (CLSM). Results: TEM, SEM, and SIM images showed that CMC had a positive effect on stabilizing amorphous calcium phosphate (ACP) and promoting intrafibrillar mineralization, while extrafibrillar mineralization was formed without CMC. Furthermore, hardness evaluation and µTBS proved that CMC significantly increased dentin hardness and bond strength. CLSM indicated that CMC could create a significantly better bond interfacial integrity with less of a micro-gap in ACAD. Significance: CMC possessed the ability to promote intrafibrillar mineralization and remineralization in demineralized caries dentin lesions, as well as improve bond performance, which implied its potential in carious dentin demineralization or dentin hypersensitivity and possibly even as a possible material for indirect pulp-capping, to deal with deep caries. Highlights: CMC possessed the ability to induce intrafibrillar mineralization effectively; the bond strength and bond durability of demineralized caries dentin were improved via CMC-induced remineralization; the CMC-induced remineralization complex is a potential material for indirect pulp-capping, to deal with deep caries.

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

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

Chemical Modification of Chitosan for Developing Cancer Nanotheranostics

Cancer is a worldwide public health issue that has not been conquered. Theranostics, the combination of a therapeutic drug and imaging agent in one formulation using nanomaterials, has been developed to better cure cancer in recent years. Although diverse biomaterials have been applied in cancer theranostics, chitosan (CS), a natural polysaccharide bearing easy modification sites with excellent biocompatibility and biodegradability, shows great potential for developing cancer nanotheranostics. In this review, we seek to describe the chemical functionalities of CS used in cancer theranostics and their synthesis methods. We also present recent discoveries and research progresses on how the CS functionalization could improve the delivery efficiency of CS-based nanotheranostics. Finally, we report several case studies about the application of CS-based nanotheranostics. This paper focuses on the strategies to construct CS-based theranostics systems via chemical routes and highlights their applications in cancer treatment, which can provide useful references for further studies.

Fabrication and functionalization of biocompatible carboxymethyl chitosan/gelatin membranes via anodic electrophoretic deposition

A biocompatible CMC/G membrane for titanium substrates has been fabricated in an eco-friendly manner and could be a promising carrier for negatively charged agents.

Chitosan Functionalization: Covalent and Non-Covalent Interactions and Their Characterization

Chitosan (CS) is a natural biopolymer that has gained great interest in many research fields due to its promising biocompatibility, biodegradability, and favorable mechanical properties. The versatility of this low-cost polymer allows for a variety of chemical modifications via covalent conjugation and non-covalent interactions, which are designed to further improve the properties of interest. This review aims at presenting the broad range of functionalization strategies reported over the last five years to reflect the state-of-the art of CS derivatization. We start by describing covalent modifications performed on the CS backbone, followed by non-covalent CS modifications involving small molecules, proteins, and metal adjuvants. An overview of CS-based systems involving both covalent and electrostatic modification patterns is then presented. Finally, a special focus will be given on the characterization techniques commonly used to qualify the composition and physical properties of CS derivatives.

Angiopep-2-Modified Carboxymethyl Chitosan-Based pH/Reduction Dual-Stimuli-Responsive Nanogels for Enhanced Targeting Glioblastoma

Glioblastoma (GBM) is a fatal brain tumor with poor prognosis. Blood-brain barrier (BBB) prevents the effective delivery of chemotherapeutic agents to GBM. Herein, we developed a pH/reduction-sensitive carboxymethyl chitosan nanogel (CMCSN) modified by targeting peptide angiopep-2 (ANG) and loaded with doxorubicin (DOX). The multifunctional nanogel (DOX-ANG-CMCSN) exhibited good pH and reduction sensitivity, ideal stability, and biocompatibility. Its hydrodynamic diameter was 190 nm, drug loading was 12.7%, and the cumulative release rate of 24 h was 82.3% under the simulated tumor microenvironment. More importantly, the modification of ANG significantly enhanced BBB penetration and tumor targeting ability both in vivo and in vitro. DOX-ANG-CMCSN achieved 2-3-fold higher uptake and an enhanced antitumor activity compared with nontargeted DOX-CMCSN. Therefore, the targeted nanogels with the pH/reduction dual-stimuli response may provide a promising platform for GBM-targeted chemotherapy.

Gelation process of carboxymethyl chitosan-zinc supramolecular hydrogel studied with fluorescence imaging and mathematical modelling

Herein we report on a detailed study about the gelation kinetics of carboxymethyl chitosan-zinc (CMCh-Zn) supramolecular hydrogel by taking advantage of its intrinsic fluorescence property. A specific gelation device is designed and the gel front can be directly visualized under 365 nm UV light. The results show that when increasing Zn²⁺ concentration from 0.1 M to 1.0 M, the apparent diffusion coefficient increases gradually from 2.72 × 10^-6 cm²/s to 4.50 × 10^-6 cm²/s. The gelation kinetics then is described with a "zero order" mathematical model, proving that the gel thickness is related to the square root of the gelation time and the diffusion step is the controlling step of the gelation process. Later a more advanced model, developed in 1D geometry and solved numerically, is used to describe and predict experimental results, proving its reliability and the correct description of all the phenomena involved in the gelation process of CMCh-Zn hydrogel.

Hydrogels Based on Oxidized Cellulose Sulfates and Carboxymethyl Chitosan: Studies on Intrinsic Gel Properties, Stability, and Biocompatibility

Cellulose and chitosan are excellent components for the fabrication of bioactive scaffolds, as they are biocompatible and abundantly available. Their derivatives Ocarboxymethyl chitosan (CMChi) and oxidized cellulose sulfate (oxCS) can form in situ gelling, bioactive hydrogels, due to the formation of imine bonds for crosslinking. Here the influence of the degrees of sulfation (DS), oxidation (DO), and the molecular weight of oxCS on intrinsic and rheological properties of such hydrogels and their ability to support the survival and growth of human-adipose-derived stem cells (hADSC) is investigated. It is found that the pH of the hydrogels is generally slightly acidic, while their network density and E-modulus are found to be dependent on the DS and DO, which makes the properties of hydrogels tunable. Extensive studies show that hydrogels can be stable for up to 14 days and that their stability is largely dependent on the DO, molecular weight, and the components mixing ratio. Cytotoxicity studies of the hydrogel with hADSCs show biocompatible gels in dependence on the molecular weight and degree of oxidation with viable cells up to 14 days. These findings can help to develop specifically tailored hydrogels for tissue engineering applications to replace different types of connective tissue.

Chitosan-based nanoparticle co-delivery of docetaxel and curcumin ameliorates anti-tumor chemoimmunotherapy in lung cancer

The application of traditional chemotherapy drugs for lung cancer has obvious limitations, such as toxic side effects, uncontrolled drug-release, poor bioavailability, and drug-resistance. Thus, to address the limitations of free drugs and improve treatment effects, we developed novel T7 peptide-modified nanoparticles (T7-CMCS-BAPE, CBT) based on carboxymethyl chitosan (CMCS), which is capable of targeted binding to the transferrin receptor (TfR) expressed on lung cancer cells and precisely regulating drug-release according to the pH value and reactive oxygen species (ROS) level. The results showed that the drug-loading content of docetaxel (DTX) and curcumin (CUR) was approximately 7.82% and 6.48%, respectively. Good biosafety was obtained even when the concentration was as high as 500 μg/mL. More importantly, the T7-CMCS-BAPE-DTX/CUR (CBT-DC) complexes exhibited better in vitro and in vivo anti-tumor effects than DTX monotherapy and other nanocarriers loaded with DTX and CUR alone. Furthermore, we determined that CBT-DC can ameliorate the immunosuppressive micro-environment to promote the inhibition of tumor growth. Collectively, the current findings help lay the foundation for combinatorial lung cancer treatment.

Advances in Injectable and Self-healing Polysaccharide Hydrogel Based on the Schiff Base Reaction

Injectable hydrogel possesses great application potential in disease treatment and tissue engineering, but damage to gel often occurs due to the squeezing pressure from injection devices and the mechanical forces from limb movement, and leads to the rapid degradation of gel matrix and the leakage of the load material. The self-healing injectable hydrogels can overcome these drawbacks via automatically repairing gel structural defects and restoring gel function. The polysaccharide hydrogels constructed through the Schiff base reaction own advantages including simple fabrication, injectability, and self-healing under physiological conditions, and therefore have drawn extensive attention and investigation recently. In this short review, the preparation and self-healing properties of the polysaccharide hydrogels that is established on the Schiff base reaction are focused on and their biological applications in drug delivery and cell therapy are discussed.