Chitosan Sulfate Research Articles

Study of the Skin-Resorptive Properties of Chitosan

The Aim of the Work: study of the skin-resorptive and sensitizing effects of various chitosan de-rivatives. Material and Methods: To study the skin-resorptive and allegnizing effects of chitosan sulfate and chitosan with furacilin according to the recommendations for the study of the toxicological proper-ties of drugs. Results: For the first time, a complex of preclinical experimental studies of various chitosan deriva-tives developed at the nstitute of Polymer Chemistry and Physics of the Academy of Sciences of the Republic of Uzbekistan was carried out. It was revealed that they do not have a resorptive and irritating effect on the skin and mucous membranes of the eyes, does not cause sensitization of the body of guinea pigs. The drugs do not have a cumulative effect and sensitizing effect. Conclusions: • Chitosan sulfate and chitosan preparations with furacilin do not have a skin-resorptive effect and a locally irritating effect. • Chitosan sulfate and chitosan preparations with furacilin do not have an allergenic effect.

Sprayable anti-adhesive hydrogel for peritoneal macrophage scavenging in post-surgical applications

Post-surgical adhesions frequently occur after intra-abdominal surgery, leading to severe complications. Despite the development of various types of adhesion barriers to address post-surgical adhesions, several limitations persist, including off-target localization, handling difficulties, and potential immunogenicity. Here, we report a spray-type adhesion barrier for broad, fast application, forming two sequential networks. The first network is formed by a polyelectrolyte complex of sulfated hyaluronic acid and chitosan, while the second network is established through pluronic® F127 thermogelation. This sprayable barrier served as both a physical protector for the damaged peritoneum and an immunomodulator for peritoneal macrophages, as evidenced its effectiveness in a rat ischemic button model. Taken together, this efficient adhesion barrier presents a promising solution for post-surgical adhesions.

Anticoagulant Protective Effects of Sulfated Chitosan Derived From the Internal Bone of Spineless Cuttlefish (Sepiella inermis).

Background This study investigated the anticoagulant properties of sulfated chitosan derived from the internal bone of the spineless cuttlefish Sepiella inermis. Chitosan, a biopolymer, is used in various biomedical applications including anticoagulation. Sulfation of chitosan enhances its biological activity, making it a potential therapeutic agent. This study explored the efficacy of sulfated chitosan in preventing blood clot formation to provide a novel anticoagulant alternative. Objectives This study aimed to synthesize and characterize the anticoagulant properties of sulfated chitosan extracted from the internal bone of the spineless cuttlefish S. inermis using Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and X-Ray Diffraction (XRD) and evaluate the anticoagulant properties of sulfated chitosan extracted from the internal bone of spineless cuttlefish S. inermis. Materials and methods Chitin and chitosan were extracted from the cuttlebone of a specimen of S. inermis, and sulfated chitosan was synthesized by sulfation of chitosan. Sulfated chitosan was subsequently used to evaluate its anticoagulant properties using tests such as activated partial thromboplastin time (APTT) and prothrombin time (PT). Characteristic investigations were conducted, including FTIR, FESEM, and XRD analyses. Results The results of this study suggested the possibility of using S. inermis internal bone as an unconventional source of natural anticoagulant that can be combined with biomedical applications. Anticoagulant activity measured using APTT and PT showed that sulfated chitosan was a strong anticoagulant. Conclusion We examined the anticoagulant activity of S. inermis extract using thrombin and activated partial thromboplastin times. Our results demonstrated the heparin-like anticoagulant action of the extracted sulfated chitosan, suggesting that it may be a great alternative anticoagulant treatment.

Kinetics of Calcite Nucleation onto Sulfated Chitosan Derivatives and Implications for Water-Polysaccharide Interactions during Crystallization of Sparingly Soluble Salts.

Anionic macromolecules are found at sites of CaCO3 biomineralization in diverse organisms, but their roles in crystallization are not well-understood. We prepared a series of sulfated chitosan derivatives with varied positions and degrees of sulfation, DS(SO3 -), and measured calcite nucleation rate onto these materials. Fitting the classical nucleation theory model to the kinetic data reveals the interfacial free energy of the calcite-polysaccharide-solution system, γnet, is lowest for nonsulfated controls and increases with DS(SO3 -). The kinetic prefactor also increases with DS(SO3 -). Simulations of Ca2+-H2O-chitosan systems show greater water structuring around sulfate groups compared to uncharged substituents, independent of sulfate location. Ca2+-SO3 - interactions are solvent-separated by distances that are inversely correlated with DS(SO3 -) of the polysaccharide. The simulations also predict SO3 - and NH3 + groups affect the solvation waters and HCO3 - ions associated with Ca2+. Integrating the experimental and computational evidence suggests sulfate groups influence nucleation by increasing the difficulty of displacing near-surface water, thereby increasing γnet. By correlating γnet and net charge per monosaccharide for diverse polysaccharides, we suggest the solvent-separated interactions of functional groups with Ca2+ influence thermodynamic and kinetic components to crystallization by similar solvent-dominated processes. The findings reiterate the importance of establishing water structure and properties at macromolecule-solution interfaces.

Chitosan and hyaluronic acid based injectable dual network hydrogels - Mediating antimicrobial and inflammatory modulation to promote healing of infected bone defects

In bone defects, infections lead to excessive inflammation, increased bacterial, and bone lysis, resulting in irregular wounds that hinder new bone regeneration. Injectable bioactive materials with adequate antimicrobial activity and strong osteogenic potential are urgently required to remedy irregular defects, eradicate bacteria, and facilitate the generation of new bone tissue. In this research, injectable dual-network composite hydrogels consisting of sulfated chitosan, oxidized hyaluronic acid, β-sodium glycerophosphate, and CuSr doped mesoporous bioactive glass loaded with bone morphogenetic protein (CuSrMBGBMP-2) were utilized for the first time to treat infectious bone defects. Initially, the hydrogel was injected into the wound at 37 °C with minimal invasion to establish a stable state and prevent hydrogel loss. Subsequently, sulfated chitosan eliminated bacteria at the wound site and facilitated cell proliferation with oxidized hyaluronic acid. Additionally, CuSrMBGBMP-2 strengthened antibacterial properties, regulated inflammatory reactions, promoted angiogenesis and osteogenic differentiation, addressing the deficiency in late-stage osteogenesis. Specifically, the injectable dual-network hydrogel based on chitosan and hyaluronic acid is minimally invasive, offering antibacterial, anti-inflammatory, pro-angiogenic, and bone regeneration properties. Therefore, this hydrogel with injectable dual network properties holds great promise for the treatment of bone infections in the future.

Investigating layer-by-layer chitosan-dextran sulfate-coated mesoporous silica as a pH-sensitive drug delivery system

Mesoporous silica nanoparticles (MSNPs) coated by chitosan (CS) were shown to be a proper candidate as a carrier for drug delivery purposes. However, choosing the suitable drug-containing complexes to be applied on MSNPs-CS is of much greater importance to evaluate the possible candidate for an efficient combination of cell viability, drug release kinetics, and atherosclerosis prevention. In this regard, this study concentrates on the synthesis and assessment of coated MSNPs-CS designed for drug delivery purposes. The MSNPs are coated with polyelectrolyte complexes (PEC) composed of CS and dextran sulfate (MSNPs-CS-DX), serving as a versatile drug carrier with favorable biological characteristics. CS-DX is applied to MSNPs without requiring complex or multi-step synthesis procedures. Rosuvastatin, a cholesterol-lowering medication, is chosen for its therapeutic relevance. Additionally, CS-DX is found to relatively impede the uptake of low-density lipoproteins (LDLs) by macrophages, enhancing their potential therapeutic utility. FTIR pattern, FESEM, and TEM images prove MSNPs-CS-DX formation. DLS measurement demonstrates the average particle size of 110 nm for MSNPs, with the combined thickness of CS and DX layers ranging from 10 to 15 nm. BET test is carried out to evaluate the pore size and porosity of structure, showing outstanding results that cause an entrapment efficiency of 57% for MSNPs-CS-DX. Furthermore, the findings demonstrate the pH sensitivity of MSNPs-CS-DX on drug release kinetics. Notably, the CS-DX layer exhibits a significant enhancement in cell viability of human umbilical vein endothelial cells (HUVEC) by approximately 24% within a 24 h timeframe compared to MSNPs lacking CS-DX.Graphical

Advancements in the Synthesis and Functionalization of Zinc Oxide-Based Nanomaterials for Enhanced Oral Cancer Therapy.

The fabrication of zinc oxide-based nanomaterials (including natural and synthetic polymers like sulfated polysaccharide, chitosan, and polymethyl methacrylate) has potential to improve oral cancer treatment strategies. This comprehensive review explores the diverse synthesis methods employed to fabricate zinc oxide nanomaterials tailored for oral cancer applications. Several synthesis processes, particularly sol-gel, hydrothermal, and chemical vapor deposition approaches, are thoroughly studied, highlighting their advantages and limitations. The review also examines how synthesis parameters, such as precursor selection, the reaction temperature, and growth conditions, influence both the physicochemical attributes and biological efficacy of the resulting nanomaterials. Furthermore, recent advancements in surface functionalization and modification strategies targeted at improving the targeting specificity and pharmaceutical effectiveness of zinc oxide-based nanomaterials in oral cancer therapy are elucidated. Additionally, the review provides insights into the existing issues and prospective views in the field, emphasizing the need for further research to optimize synthesis methodologies and elucidate the mechanisms underlying the efficacy of zinc oxide-based nanoparticles in oral cancer therapy.

Sulfated Chitosan-Modified CuS Nanocluster: A Versatile Nanoformulation for Simultaneous Antibacterial and Bone Regenerative Therapy in Periodontitis.

Periodontitis, a prevalent chronic inflammatory disease worldwide, is triggered by periodontopathogenic bacteria, resulting in the progressive destruction of periodontal tissue, particularly the alveolar bone. To effectively address periodontitis, this study proposed a nanoformulation known as CuS@MSN-SCS. This formulation involves coating citrate-grafted copper sulfide (CuS) nanoparticles with mesoporous silica (MSNs), followed by surface modification using amino groups and sulfated chitosan (SCS) through electrostatic interactions. The objective of this formulation is to achieve efficient bacteria removal by inducing ROS signaling pathways mediated by Cu2+ ions. Additionally, it aims to promote alveolar bone regeneration through Cu2+-induced pro-angiogenesis and SCS-mediated bone regeneration. As anticipated, by regulating the surface charges, the negatively charged CuS nanoparticles capped with sodium citrate were successfully coated with MSNs, and the subsequent introduction of amine groups using (3-aminopropyl)triethoxysilane was followed by the incorporation of SCS through electrostatic interactions, resulting in the formation of CuS@MSN-SCS. The developed nanoformulation was verified to not only significantly exacerbate the oxidative stress of Fusobacterium nucleatum, thereby suppressing bacteria growth and biofilm formation in vitro, but also effectively alleviate the inflammatory response and promote alveolar bone regeneration without evident biotoxicity in an in vivo rat periodontitis model. These findings contribute to the therapeutic effect on periodontitis. Overall, this study successfully developed a nanoformulation for combating bacteria and facilitating alveolar bone regeneration, demonstrating the promising potential for clinical treatment of periodontitis.

Design of a New Vaccine Prototype against Porcine Circovirus Type 2 (PCV2), M. hyopneumoniae and M. hyorhinis Based on Multiple Antigens Microencapsulation with Sulfated Chitosan.

This work evaluated in vivo an experimental-multivalent-vaccine (EMV) based on three Porcine Respiratory Complex (PRC)-associated antigens: Porcine Circovirus Type 2 (PCV2), M. hyopneumoniae (Mhyop) and M. hyorhinis (Mhyor), microencapsulated with sulfated chitosan (M- ChS + PRC-antigens), postulating chitosan sulphate (ChS) as a mimetic of the heparan sulfate receptor used by these pathogens for cell invasion. The EMV was evaluated physicochemically by SEM (Scanning-Electron-Microscopy), EDS (Energy-Dispersive-Spectroscopy), Pdi (Polydispersity-Index) and zeta potential. Twenty weaned pigs, distributed in four groups, were evaluated for 12 weeks. The groups 1 through 4 were as follows: 1-EMV intramuscular-route (IM), 2-EMV oral-nasal-route (O/N), 3-Placebo O/N (M-ChS without antigens), 4-Commercial-vaccine PCV2-Mhyop. qPCR was used to evaluate viral/bacterial load from serum, nasal and bronchial swab and from inguinal lymphoid samples. Specific humoral immunity was evaluated by ELISA. M-ChS + PRC-antigens measured between 1.3-10 μm and presented low Pdi and negative zeta potential, probably due to S (4.26%). Importantly, the 1-EMV protected 90% of challenged animals against PCV2 and Mhyop and 100% against Mhyor. A significant increase in antibody was observed for Mhyor (1-EMV and 2-EMV) and Mhyop (2-EMV), compared with 4-Commercial-vaccine. No difference in antibody levels between 1-EMV and 4-Commercial-vaccine for PCV2-Mhyop was observed. Conclusion: The results demonstrated the effectiveness of the first EMV with M-ChS + PRC-antigens in pigs, which were challenged with Mhyor, PCV2 and Mhyop, evidencing high protection for Mhyor, which has no commercial vaccine available.

Obtaining chitosan sulfate nanoparticles in an aqueous medium and their colloidal protection with polysaccharides

Obtaining chitosan sulfate nanoparticles in an aqueous medium and their colloidal protection with polysaccharides

Sulfated Polysaccharide-Based Nanocarrier Drives Microenvironment-Mediated Cerebral Neurovascular Remodeling for Ischemic Stroke Treatment.

Stroke is a leading cause of global mortality and severe disability. However, current strategies used for treating ischemic stroke lack specific targeting capabilities, exhibit poor immune escape ability, and have limited drug release control. Herein, we developed an ROS-responsive nanocarrier for targeted delivery of the neuroprotective agent rapamycin (RAPA) to mitigate ischemic brain damage. The nanocarrier consisted of a sulfated chitosan (SCS) polymer core modified with a ROS-responsive boronic ester enveloped by a red blood cell membrane shell incorporating a stroke homing peptide. When encountering high levels of intracellular ROS in ischemic brain tissues, the release of SCS combined with RAPA from nanoparticle disintegration facilitates effective microglia polarization and, in turn, maintains blood-brain barrier integrity, reduces cerebral infarction, and promotes cerebral neurovascular remodeling in a mouse stroke model involving transient middle cerebral artery occlusion (tMCAO). This work offers a promising strategy to treat ischemic stroke therapy.

26SCS-Loaded SilMA/Col Composite Sponge with Well-Arranged Layers Promotes Angiogenesis-Based Diabetic Wound Repair by Mediating Macrophage Inflammatory Response.

Diabetic wound healing is a significant clinical challenge because abnormal immune cells in the wound cause chronic inflammation and impair tissue regeneration. Therefore, regulating the behavior and function of macrophages may be conducive to improving treatment outcomes in diabetic wounds. Herein, sulfated chitosan (26SCS)-containing composite sponges (26SCS-SilMA/Col-330) with well-arranged layers and high porosity were constructed based on collagen and silk fibroin, aiming to induce an appropriate inflammatory response and promote angiogenesis. The results indicated that the ordered topological structure of composite sponges could trigger the pro-inflammatory response of Mφs in the early stage, and rapid release of 26SCS in the early and middle stages (within the concentration range of 1-3 mg/mL) induced a positive inflammatory response; initiated the pro-inflammatory reaction of Mφs within 3 days; shifted M1 Mφs to the M2 phenotype within 3-7 days; and significantly up-regulated the expression of two typical angiogenic growth factors, namely VEGF and PDGF-BB, on day 7, leading to rapid HUVEC migration and angiogenesis. In vivo data also demonstrated that on the 14th day after surgery, the 26SCS-SilMA/Col-330-implanted areas exhibited less inflammation, faster re-epithelialization, more abundant collagen deposition and a greater number of blood vessels in the skin tissue. The composite sponges with higher 26SCS contents (the (5.0) 26SCS-SilMA/Col-330 and the (7.5) 26SCS-SilMA/Col-330) could better orchestrate the phenotype and function of Mφs and facilitate wound healing. These findings highlight that the 26SCS-SilMA/Col-330 sponges developed in this work might have great potential as a novel dressing for the treatment of diabetic wounds.

Investigation of inhibitory effect of sulfated chitosan oligomer on human heparanase enzyme: in silico and in vitro studies

Deaths from cancer are widespread worldwide and the numbers continue to increase day by day. During the disease progression of cancer in cells, many of its metabolic activities change. Increased heparanase enzyme release is just one example. Following heparanase enzyme activity, many molecules interact with the remodeling of glycosaminoglycan structures, which triggers the release of different enzymes, cytokines, and growth factors, including fibroblast growth factors (FGF1 and FGF2), vascular endothelial growth factor (VEGF), hepatocyte growth factor, transforming growth factor β and platelet-derived growth factor. These are the most important factors in metastasis due to the formation of new vascular structures caused by those elements. To reduce tumor growth and metastasis, various drugs have been designed by modifying chitosan and its derivatives. In this study, we used chitosan oligomer (A), sulfated chitosan oligomer (ShCsO) (B), heparin (C), phosphate monomer (D1) of PI-88 and sulfate monomer (D2) of PI-88 as heparanase inhibitors. We modified the chitosan oligomer with chlorosulfonic acid to synthesize ShCsO to investigate its inhibitory effects on human serum heparanase. Also examined were molecular docking; molecular dynamics (MD); adsorption, distribution, metabolism, elimination and toxicity (ADMET); and target prediction. ShCsO decreased enzyme activity at a concentration of 0.0001 mg/mL. The docking scores of A, B and C from in silico studies were −6.254, −6.936 and −6.980 kcal/mol, respectively, and the scores for the two different PI-88 monomers were −5.741 and −5.824 kcal/mol. These results show that ShCsO may be a potential drug candidate for treating cancer. Communicated by Ramaswamy H. Sarma

Design and synthesis of polypyrrole conductive ink based on sulfated chitosan for bactericide carbendazim detection

Conductive polymers (CPs) are typically insoluble in solvents, and devising biocompatible hydrophilic CPs is challenging and imperative to expand the applications of CPs. Herein, sulfated chitosan (SCS) is used as a green dopant instead of toxic poly(styrene sulfonate) (PSS), and SCS:polypyrrole (SCS:PPy) conductive ink is prepared by in situ polymerization. Due to the complex structure between PPy and SCS polyanion, the synthesized SCS:PPy dispersion forms a well-connected electric pathway and confers superior conductivity, dispersion stability, good film-forming ability, and high electrical stability. As proof of our concept, electrochemical sensing utilizing an SCS:PPy-modified screen-printed carbon electrode (SPCE) was performed towards carbendazim (CBZ). The SCS:PPy on the SPCE surface displayed greater sensitivity to CBZ because the conductive complex structure eased the electrocatalytic action of SCS:PPy by dramatically increasing the current intensity of CBZ oxidation and notably ameliorating stability. The sensor unveils the lowest detection value of 1.02 nM with a linear range of 0.05 to 906 μM for sensing trace CBZ by utilizing the pulse voltammetry technique. Interestingly, this senor shows excellent selectivity towards CBZ due to the formation of substantial interactions between SCS:PPy and CBZ, as demonstrated by molecular simulation studies. Furthermore, this sensor can precisely monitor CBZ in actual fruit and river water samples with satisfactory results. This study sheds light on the design and synthesis of sustainable hydrophilic CPs in the fabrication of sensors.

2-N, 6-O sulfated chitosan evokes periosteal stem cells for bone regeneration

Musculoskeletal injuries and bone defects represent a significant clinical challenge, necessitating innovative approaches for effective bone tissue regeneration. In this study, we investigated the potential of harnessing periosteal stem cells (PSCs) and glycosaminoglycan (GAG)-mimicking materials for in situ bone regeneration. Our findings demonstrated that the introduction of 2-N, 6-O sulfated chitosan (26SCS), a GAG-like polysaccharide, enriched PSCs and promoted robust osteogenesis at the defect area. Mechanistically, 26SCS amplifies the biological effect of endogenous platelet-derived growth factor-BB (PDGF-BB) through enhancing the interaction between PDGF-BB and its receptor PDGFRβ abundantly expressed on PSCs, resulting in strengthened PSC proliferation and osteogenic differentiation. As a result, 26SCS effectively improved bone defect repair, even in an osteoporotic mouse model with lowered PDGF-BB level and diminished regenerative potential. Our findings suggested the significant potential of GAG-like biomaterials in regulating PSC behavior, which holds great promise for addressing osteoporotic bone defect repair in future applications.

Sulfated Chitosan Nanofibrous Scaffolds Seeded With Adipose Stem Cells Promote Ischemic Wound Healing in a Proangiogenic Strategy.

Ischemic wounds are chronic wounds with poor blood supply that delays wound reconstruction. To accelerate wound healing and promote angiogenesis, adipose-derived stem cells (ADSCs) are ideal seed cells for stem cell-based therapies. Nevertheless, providing a favorable environment for cell proliferation and metabolism poses a substantial challenge. A highly sulfated heparin-like polysaccharide 2-N, 6-O-sulfated chitosan (26SCS)-doped poly(lactic-co-glycolic acid) scaffold (S-PLGA) can be used due to their biocompatibility, mechanical properties, and coagent 26SCS high affinity for growth factors. In this study, a nano-scaffold system, constructed from ADSCs seeded on electrospun fibers of modified PLGA, was designed to promote ischemic wound healing. The S-PLGA nanofiber membrane loaded with adipose stem cells ADSCs@S-PLGA was prepared by a co-culture in vitro, and the adhesion and compatibility of cells on the nano-scaffolds were explored. Scanning electron microscopy was used to observe the growth state and morphological changes of ADSCs after co-culture with PLGA electrospun fibers. The proliferation and apoptosis after co-culture were detected using a Cell Counting Kit-8 kit and flow cytometry, respectively. An ischemic wound model was then established, and we further studied the ability of ADSCs@S-PLGA to promote wound healing and angiogenesis. We successfully established ischemic wounds on the backs of rats and demonstrated that electrospun fibers combined with the biological effects of adipose stem cells effectively promoted wound healing and the growth of microvessels around the ischemic wounds. Phased research results can provide a theoretical and experimental basis for a new method for promoting clinical ischemic wound healing.

Sulfated oligosaccharide activates endothelial Notch for inducing macrophage-associated arteriogenesis to treat ischemic diseases.

Ischemic diseases lead to considerable morbidity and mortality, yet conventional clinical treatment strategies for therapeutic angiogenesis fall short of being impactful. Despite the potential of biomaterials to deliver pro-angiogenic molecules at the infarct site to induce angiogenesis, their efficacy has been impeded by aberrant vascular activation and off-target circulation. Here, we present a semisynthetic low-molecular sulfated chitosan oligosaccharide (SCOS) that efficiently induces therapeutic arteriogenesis with a spontaneous generation of collateral circulation and blood reperfusion in rodent models of hind limb ischemia and myocardial infarction. SCOS elicits anti-inflammatory macrophages' (Mφs') differentiation into perivascular Mφs, which in turn directs artery formation via a cell-to-cell communication rather than secretory factor regulation. SCOS-mediated arteriogenesis requires a canonical Notch signaling pathway in Mφs via the glycosylation of protein O-glucosyltransferases 2, which results in promoting arterial differentiation and tissue repair in ischemia. Thus, this highly bioactive oligosaccharide can be harnessed to direct efficiently therapeutic arteriogenesis and perfusion for the treatment of ischemic diseases.

Fabrication of affinity-based drug delivery systems based on electrospun chitosan sulfate/poly(vinyl alcohol) nanofibrous mats

Benign electrospinning of chitosan in aqueous medium is an open challenge mainly due to its insolubility in neutral pH and inter- and intramolecular hydrogen bonding interactions. Here, we developed a simple and widely-used methodology to improve the chitosan electrospinnability through the sulfation of chitosan and its further mixing with poly(vinyl alcohol) for the first time. The FTIR, 1H NMR and elemental analyses showed the successful sulfation of chitosan. Furthermore, the viscosity and electrical conductivity measurements revealed the high solubility of chitosan sulfate (CS) in aqueous media. In the next step, a uniform electrospun nanofibrous mat of CS/PVA was fabricated with a fiber diameter ranging from 90 to 340 nm. The crosslinked CS/PVA (50/50) nanofibrous mat as the optimum sample showed a swelling ratio of 290 ± 4 % and a high Young's modulus of 3.75 ± 0.10 GPa. Finally, malachite green (MG) as a cationic drug model was loaded into different samples of chitosan film, CS film, and CS/PVA (50/50) nanofibrous mat and its release behavior was studied. The results of these analyses revealed that the CS/PVA (50/50) nanofibrous mat can successfully load higher contents of the MG and also release it in a sustained manner.

Thermoresponsive hydrogels with sulfated polysaccharide-derived copolymers: the effect of carbohydrate backbones on the responsive and mechanical properties

Thermoresponsive hydrogels based on ionic cellulose/chitosan are widely used various fields, such as smart windows and tissue engineering, while the effect of carbohydrate backbones of cellulose/chitosan on the thermal response and mechanical properties of hydrogels has received less attention so far. Herein, poly(2(dimethylamino)ethyl methacrylate) (PDMAEMA)-grafted cellulose sulfate (P-CS) and PDMAEMA-grafted chitosan sulfate (P-CHS) as research models are successfully synthesized through multi-step reactions. The P-CS and P-CHS polymers are further applied in crosslinked polyacrylamide networks, resulting in the P-CS and P-CHS hydrogels. Compared to P-CS hydrogels, P-CHS hydrogels could obviously block the transmission of visible light when the temperature is changed from 25 to 42 °C. In contrast to P-CHS hydrogels, the P-CS hydrogels change easily from soft and weak state to stiff and strong state according to their mechanical behaviors. These results indicate that different carbohydrate backbones of cellulose and chitosan should have caused distinct aggregation behaviors of corresponding P-CS and P-CHS hydrogels, which are accompanied by different light transmittance and mechanical properties.Graphical abstract Thermoresponsive hydrogels using PDMAEMA-grafted ionic cellulose sulfate (P-CS) and chitosan sulfate (P-CHS) are successfully prepared. Distinct carbohydrate backbone displayed different effects on the thermoresponsive and mechanical properties of hydrogels.

Stainless steel and titanium alloys coated with sulfated chitosan to improve hemocompatibility properties

The main drawbacks of blood-contacting metallic devices are corrosion and thrombus formation on the surface, so polymeric coatings have been proposed to improve its hemocompatibility. Sulfated chitosan (SC) was obtained from natural chitosan (NC) reaction with chlorosulfonic acid to be used as a coating for metallic surfaces. The sulfated chitosan showed no platelet aggregation, an extended clotting time, and non-toxicity to rat fibroblast L929 cells. In this study, stainless steel (SS) and titanium alloys modified with TiO2 nanotube (NTT) growth received a NC and SC coating. The titanium surface coated with sulfated chitosan presented the lowest percentage of platelet coverage area. Sulfated chitosan proved to be a promising material for use as a coating for metallic surfaces applied for cardiovascular devices.