Ecofriendly flame-retardant composite aerogel derived from polysaccharide: Preparation, flammability, thermal kinetics, and mechanism.

Bio-based aerogel (polysaccharide cryogel) have led to a growing interest because of eco-friendliness, sustainability and excellent thermal insulation properties. Herein, we report an eco-friendly strategy to construct lightweight and porous sodium alginate/carboxymethyl cellulose/chitosan polysaccharide-based composite aerogels (SCC-B) by freeze-drying and post-cross-linking technology. The ester cross-linking of polysaccharide component achieved strong web-like entangled structure when using 1,2,3,4-butanetetracarboxylic acid and sodium hypophosphite as eco-friendly co-additives, meanwhile significantly improved flame retardancy of SCC-B due to phosphorylation. The thermal kinetic behavior of SCC-B was investigated by Flynn-Wall-Ozawa and Kissinger models. Results indicated that peak heat release rate and total heat release of SCC-B decreased from 30 W/g to 20 W/g and 15 kJ/g to 10 kJ/g, respectively. Furthermore, the second-degree burn time of SCC-B reached up to 87.1 s under heat exposure of 11.3 kW/m2. These characteristics combine to suggest hopeful prospects for use of SCC-B in the fields of fire-protection clothing as a renewable flame-retardant material.

Immediate-Release Formulations Produced via Twin-Screw Melt Granulation: Systematic Evaluation of the Addition of Disintegrants.

The current study evaluated the effect of location and amount of various superdisintegrants on the properties of tablets made by twin-screw melt granulation (TSMG). Sodium-croscarmellose (CCS), crospovidone (CPV), and sodium starch glycolate (SSG) were used in various proportions intra- and extra-granular. Tabletability, compactibility, compressibility as well as friability, disintegration, and dissolution performance were assessed. The extra-granular addition resulted in the fasted disintegration and dissolution. CPV performed superior to CCS and SSG. Even if the solid fraction (SF) of the granules was lower for CPV, only a minor decrease in tabletability was observed, due to the high plastic deformation of the melt granules. The intra-granular addition of CPV resulted in a more prolonged dissolution profile, which could be correlated to a loss in porosity during tableting. The 100% intra-granular addition of the CPV resulted in a distinct decrease of the disintegration efficiency, whereas the performance of SSG was unaffected by the granulation process. CCS was not suitable to be used for the production of an immediate-release formulation, when added in total proportion into the granulation phase, but its efficiency was less impaired compared to CPV. Shortest disintegration (78 s) and dissolution (Q80: 4.2 min) was achieved with CPV extra-granular. Using CPV and CCS intra-granular resulted in increased disintegration time and Q80. However, at a higher level of appx. 500 s and appx. 15 min, only SSG showed a process and location independent disintegration and dissolution performance.

Water-based carbodiimide mediated synthesis of polysaccharide-amino acid conjugates: Deprotection, charge and structural analysis.

We report here a one-step aqueous method for the synthesis of isolated and purified polysaccharide-amino acid conjugates. Two different types of amino acid esters: glycine methyl ester and L-tryptophan methyl ester, as model compounds for peptides, were conjugated to the polysaccharide carboxymethylcellulose (CMC) in water using carbodiimide at ambient conditions. Detailed and systematic pH-dependent charge titration and spectroscopy (infrared, nuclear magnetic resonance: 1H, 13C- DEPT 135, 1H- 13C HMBC/HSQC correlation), UV-vis, elemental and ninhydrin analysis provided solid and direct evidence for the successful conjugation of the amino acid esters to the CMC backbone via an amide bond. As the concentration of amino acid esters increased, a conjugation efficiency of 20-80% was achieved. Activated charcoal aided base-catalyzed deprotection of the methyl esters improved the solubility of the conjugates in water. The approach proposed in this work should have the potential to tailor the backbone of polysaccharides containing di- or tri-peptides.

Ultrasound-assisted synthesis of MIL-88(Fe) coordinated to carboxymethyl cellulose fibers: A safe carrier for highly sustained release of tetracycline.

For stopping long-time harmful bacterial infection, designing a drug carrier with a highly prolonged release profile is a promising approach that is of interest to different biomedical areas. The subject of this work is to synthesis a novel carrier system through coordination of MIL-88(Fe) to carboxymethyl cellulose (CMC) for enhancing interaction between drug and carrier. We established an ultrasound-assisted synthetic method for in situ synthesis of MIL-88(Fe) in the presence of CMC resulting in CMC/MIL-88(Fe) composite. The CMC/MIL-88(Fe) was loaded with a high amount of Tetracycline (TC) by immersion of carrier to the TC aqueous solution. The release profile in the simulated physiological conditions, pH 7.4, revealed a low initial burst release followed by a sustained and prolonged release over 384 h. The in vitro cytotoxicity of CMC/MIL-88(Fe) against Human skin fibroblast (HFF-1) cells was calculated by MTT assay and showed a good cytocompatibility. The antibacterial activity was found for TC-loaded CMC/MIL-88(Fe) toward both E. coli and S. aureus with MIC 64 mg·ml-1.

A series of carboxymethyl cellulose-based antimicrobial peptide mimics were synthesized for antimicrobial applications.

Inspired by antimicrobial peptides (AMP) which could alleviate drug resistance pressure, antimicrobial peptide mimics (AMPMs) were designed timely. Here, carboxymethyl cellulose (CMC) -based AMPMs were constructed by introducing different diamines on CMC effectively. Firstly, CMC was degraded to be oligomers with different molecular weights, followed by amination reactions with different diamines respectively. After protonation, a series of AMPMs with different structures were synthesized successfully. Their antibacterial effect has been evaluated by dynamic growth curves and microdilution method. The images snapped by the confocal laser scanning microscope and transmission electron microscope have fully proved its great lethality. And the antibacterial mechanism measured by flow cytometry analysis and zeta potential detection demonstrated that the destruction of membrane potential leads to bacteria death. The excellent blood compatibility and negligible drug resistance has also been confirmed. In addition, the synthesis method is simple and environmental-friendly.

Preparation, characterization, and antibacterial property of carboxymethyl cellulose derivatives bearing tetrabutylammonium salt.

Carboxymethyl cellulose derivatives bearing tetrabutylammonium moieties (CMC-TBA) were synthesized by the acidification of carboxymethyl cellulose (CMC) followed by acid-base neutralization with tetrabutylammonium hydroxide. The products were identified by Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (NMR) spectroscopy and the degrees of substitution (DS) values were also quantified according to the integral area values in 1H NMR spectra. It was revealed that DS values had a positive relationship with the molar ratios of TBAOH to CMC. The antibacterial behaviors against gram-positive bacteria S. aureus and gram-negative bacteria E. coli were investigated using serial two-fold dilution method (MIC and MBC) and the disc diffusion method (inhibition zone). The results showed that comparison with CMC, all new CMC-TBA derivatives exhibited high antibacterial activity that depends on bacteria type and their degrees of cationization. The antibacterial action was more effective against S. aureus than E. coli, which could be attributed to the fact that the latter has a complicated bilayer structure of cell wall. Besides, an apparent tendency that the antibacterial activity of CMC-TBA derivatives enhanced with an increase in the degrees of cationization was found. This work suggests that these new derivatives can be introduced as efficient antibacterial biomaterials for biomedical purposes.

Synthesis of carboxymethyl cellulose-chitosan-montmorillonite nanosheets composite hydrogel for dye effluent remediation.

MMTNS were introduced into carboxymethyl cellulose-chitosan system to synthesize porous hydrogel adsorbent with stable structure and high dye handling capacity. Al-OH on edge of MMTNS formed hydrogen-bond (-OH···+NH3-) with -NH2 on CS, CS then cooperated with CMC via amidation and chains interleaving, forming three-dimensional hydrogel. Morphology characterization revealed that hydrogel possessed microporous open-framework structure, facilitating free entrance of macromolecular MB dye to react with internal reaction sites in hydrogel. Factor tests indicated that high removal (97%) of MB was achieved via 0.2 g/L hydrogel within 360 min even after 5 adsorption-regeneration cycles. Adsorption process followed Pseudo-first-order, Pseudo-second-order kinetic model and Sips isotherm model, owing to both monolayer physical and chemical adsorption behavior of MB molecules onto homogeneous surface of hydrogel. Adsorption mechanism was attributed to ion-exchange, groups combination of carboxyl and hydroxyl, and Si active sites reaction. Such hydrogel realized promotion of polysaccharide polymers in materials design and wastewater treatment.

Green and facile synthesis of carboxymethylcellulose/ZnO nanocomposite hydrogels crosslinked with Zn2+ ions.

A green method was used for the preparation of functional carboxymethyl cellulose (CMC) hydrogel crosslinked by divalent zinc ions and incorporated with zinc oxide nanoparticles (ZnO) without using alkaline reagents. In the process, sodium carboxymethyl cellulose was used not only as a hydrogel matrix but also for the release of free hydroxyl groups, which increases the pH of the reaction mixture, consequently leading to the formation of ZnO. The chemical structure and morphology of the hydrogels were characterized using FTIR and FE-SEM analysis, respectively. The water absorption capacity of the hydrogels was studied as a function of temperature and pH. The results of FE-SEM showed the formation of ZnO particles in the hydrogel, while the water absorption capacity results supported the formation of zinc ion cross-linking within the carboxymethylcellulose chains. The CMC/ZnO nanocomposite hydrogel exhibited strong antimicrobial activity against pathogenic bacteria E. coli and L. monocytogenes.

Synthesis of the carboxymethyl cellulose magnetic nanoparticles for efficient immobilization of prenyltransferase NovQ.

Prenyltransferase NovQ immobilized carboxymethyl cellulose magnetic nanoparticles (NCMNs) were successfully synthesized via a valuable approach integrated from nanocomposite preparation, and applied for the production of vitamin K2 using menadione hydroquinol and dimethylallyl diphosphate (DMAPP) as substrates. To investigate the interaction between nanoparticles and NovQ, we characterized the nanocomposite, and revealed that carboxymethyl cellulose (CMC) and Fe3O4 formed a core-shell structure to absorb NovQ in the reaction systems, resulting from the high affinity of immobilized materials. Meanwhile, NCMNs with excellent pH and temperature tolerance, enhanced prenylated activity, and improved stability were found. Molecular docking analysis was also conducted to justify the contribution of multiple amino acids and effect of nanoparticles on catalytic properties of NovQ. Taken together, our study introduces a promising strategy to prepare magnetic nanoparticles and improve the performance of catalyst, which aims for opening new orientations for synthesis of magnetic nanoparticles used for prenyltransferase immobilization.

Antimicrobial and Wound Treatment Aspects of Micro- and Nanoformulations of Carboxymethyl, Dialdehyde, and TEMPO-Oxidized Derivatives of Cellulose: Recent Advances.

The remedy for infected chronic wounds such as diabetic foot ulcers is more complicated particularly in the case of patients with an inefficient immune system. Also, fighting against microbial infections in the wound site by available antibiotics may not be effective because of emerging antibiotic resistance properties among pathogenic bacteria and fungi. Recently, applications of micro- and nanoformulations of biomaterials have demonstrated improved therapeutic abilities for wound dressings. In this way, carboxymethyl, dialdehyde, and 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized celluloses are common biomaterials having outstanding physicochemical and therapeutic properties compared to unmodified cellulose. Therefore, in this review, recent progress in the field of wound healing and antimicrobial activities of these derivatives are presented and discussed.

Elastase-triggered H2S delivery from polymer hydrogels.

We report an elastase-responsive, H2S-releasing hydrogel prepared by covalently crosslinking a mixture of carboxymethylcellulose and poly(ethylene glycol) with an elastase-degradable peptide functionalized with an H2S-releasing S-aroylthiooxime (SATO) unit. Addition of elastase triggered a gel-to-sol transition, which exposed SATOs, leading to more and longer H2S release compared to untriggered gels.

Water-Soluble Cellulose Derivatives as Suitable Matrices for Multifunctional Materials.

This work reports on a simple and environmentally benign route to prepare freestanding magnetic films based on cellulose derivatives through the combination of cobalt ferrite (CoFe2O4) nanoparticles with methyl cellulose (MC), hydroxypropyl cellulose (HPC), and sodium carboxymethyl cellulose (NaCMC). Nanoparticles are able to "shield" hydrogen bonding interactions between polysaccharide chains and lower the viscosity of water-dissolved MC, HPC, and NaCMC, allowing an easy film fabrication. Crack-free films with homogeneously dispersed nanoparticles having concentrations up to 50 wt % are fabricated by mechanical agitation followed by doctor blade casting. All of the nanocomposite films keep a substantial level of flexibility with elongation at break exceeding 5%. Halpin-Tsai equations serve to provide further insights on the character of matrix-CoFe2O4 interfaces. Magnetization saturation increases almost linearly with cobalt ferrite concentration up to a maximum value of ∼24-27 emu g-1 for nanocomposites containing 50 wt % of nanoparticles. The dielectric response of the films demonstrates a strong dependence on both the functional groups attached to the main cellulose chain and the ferrite nanoparticle content. The renewable character of the hosting matrices, together with the fabrication methods that solely uses water as a solvent, the decrease of the viscosity with the inclusion of fillers, particularly suitable for printable materials, and the resulting magnetic performance provide novel avenues for the replacement of traditional magnetoactive composites based on petroleum-derived polymers and avoiding the use of toxic solvents.

Photocatalytic/biodegradable film based on carboxymethyl cellulose, modified by gelatin and TiO2-Ag nanoparticles.

In this study, the composite of carboxymethyl cellulose (CMC) film modified with gelatin and TiO2-Ag nanoparticles (CMC/Gel/TiO2-Ag) was prepared and some properties of synthesized film including physicochemical and photocatalytic properties were investigated. FT-IR results showed that new interactions between the film components were created. Scanning electron microscopy (SEM) results showed that the TiO2-Ag particles with 50-100 nm distributed in the CMC/Gelatin film. The results of the mechanical test showed that the TiO2-Ag nanoparticles at low concentrations increased tensile strength (TS) and decreased strain to break (STB), but with increasing nanoparticles concentrations, TS decreased and STB increased. Photocatalytic study showed that the prepared CMC/Gel/TiO2-Ag film has good photocatalytic property. Gas chromatography was used to study photocatalytic effects of film. Increasing TiO2-Ag nano particles on the film increases the photocatalytic activity of films against NH3, ethanol and benzene.

A mussel-inspired carboxymethyl cellulose hydrogel with enhanced adhesiveness through enzymatic crosslinking.

In order to replace conventional sutures in wound closing applications, favorable hydrogels with strong wet tissue adhesion and biocompatibility have attracted considerable attention. Herein, inspired by mussel adhesive protein, a series of dopamine modified carboxymethyl cellulose (CMC-DA) hydrogels were prepared in situ using enzymatic crosslinking in the presence of horseradish peroxidase (HRP) and H2O2. The biomimetic CMC-DA hydrogel exhibited about 6-fold enhanced wet tissue adhesion strength (28.5 kPa) over the commercial fibrin glue. In addition, the gelation time, swelling ratio and rheological property of the hydrogel can be simply controlled by changing the concentrations of HRP, H2O2, and CMC-DA polymer. The gels also exhibited good biodegradation and biocompatibility in vitro. The overall results show that the CMC-DA hydrogel with enhanced wet adhesiveness will be a promising tissue adhesive material.

Synthesis and characterization of iron oxide nanoparticles/carboxymethyl cellulose core-shell nanohybrids for killing cancer cells in vitro.

Novel core-shell superparamagnetic nanofluids composed of magnetic iron oxide (Fe3O4, MION) and cobalt-doped (CoxFe3-xO4, Co-MION) nanoparticles functionalized with carboxymethyl cellulose (CMC) ligands were designed and produced via green colloidal aqueous process. The effect of the degree of substitution (DS = 0.7 and 1.2) and molecular mass (Mw) of CMC and cobalt doping concentration on the physicochemical and magnetic properties of these nanoconjugates were comprehensively investigated using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, transmission electron microscopy (TEM) with selected area electron diffraction, X-ray fluorescence, dynamic light scattering (DLS), zeta potential (ZP) analysis, vibrating sample magnetometry (VSM) and electron paramagnetic resonance spectroscopy (EPR). The results demonstrated the effect of concentration of carboxylate groups and Mw of CMC on the hydrodynamic dimension, zeta potential, and generated heat by magnetic hyperthermia of MION nanoconjugates. Co-doping of MION showed significant alteration of the electrostatic balance of charges of the nanoconjugates interpreted as effect of surface interactions. Moreover, the VSM and EPR results proved the superparamagnetic properties of these nanocolloids, which were affected by the presence of CMC and Co-doping of iron oxide nanoparticles. These magnetic nanohybrids behaved as nanoheaters for killing brain cancer cells in vitro with prospective future applications in oncology and nanomedicine.

Fabrication of carboxymethyl cellulose and graphene oxide bio-nanocomposites for flexible nonvolatile resistive switching memory devices.

Nowadays the development of natural biomaterials as promising building polymers for flexible, biodegradable, biocompatible and environmentally friendly electronic devices is of great interest. As the most common natural polymers, cellulose and its derivatives have the potential to be applied in the devices owing to the easy processing, nontoxicity and biodegradability. Here, write-once-read-many-times resistive switching devices based on biodegradable carboxymethyl cellulose-graphene oxide (CMC-GO) nanocomposite are demonstrated for the first time. The hybridization sites formed by the gelation of CMC and GO molecules contribute to the excellent memory behaviors. When compared with devices base on pure GO and CMC, the device with the Al/CMC-GO/Al/SiO2 structure exhibits brilliant write-once-read-many-times (WORM) switching characteristics such as high ON/OFF current ratio of ˜105, low switching voltage of 2.22 V, excellent stability and durability. What's more, the device shows high flexibility and good resistive switching behaviors even with soft PET substrate (Al/CMC-GO/Al/PET structure). This newly designed cellulose-graphene oxide-based polymer nanocomposites are quite cheap and easy processed for large scale manufacturing of memory devices and can further contribute to future biodegradable data storage applications such as portable stretchable displays, wearable electronics and electronic skins in the coming age of artificial intelligence.

Cross-linking of dialdehyde carboxymethyl cellulose with silk sericin to reinforce sericin film for potential biomedical application.

Developing biomaterials based on the natural biomacromolecule silk sericin from Bombyx mori cocoon is of great interest for biomedical application. Dialdehyde carboxymethyl cellulose (DCMC) is derived from periodate oxidation of carboxy- methyl cellulose. Here, we developed a novel strategy of cross-linking of sericin with DCMC via the Schiff's base reaction. Fourier transform infrared spectroscopy and scanning electron microscopy indicated the formation of Schiff's base via the blending of sericin and DCMC. The mechanical properties tests suggested the covalent cross-linking effectively enhanced the tensile strength of sericin. The swelling test and water contact angle indicated the DCMC/SS film had excellent hydrophilicity, swellability. Additionally, we demonstrated the DCMC/SS film had excellent blood compatibility, cytocompatibility and promoting cell proliferation activity by the hemolysis ratio analysis, cell adhesion, cells viability and proliferation assays. The prepared DCMC/SS film has shown great promise in biomedical applications such as wound dressing, artificial skin and tissue engineering.

Synthesis of high-performance sodium carboxymethyl cellulose-based adsorbent for effective removal of methylene blue and Pb (II).

In this work, a biobased adsorbent (CMC-PAMA) consisting of sodium carboxymethyl cellulose, polyacrylic acid and polyacrylamide was prepared by a simple thermal crosslinking method for the removal of methylene blue (MB) and Pb (II) from aqueous solutions. The CMC-PAMA showed excellent static adsorption capacities for MB and Pb (II) of 1611.44 mg·g-1 840.11 mg·g-1, respectively, indicating its excellent performance on dyes dynamic removal. The adsorption performance of the as-prepared CMC-PAMA could be fitted well with pseudo-second-order and Langmuir isothermal model. The adsorption mechanism between CMC-PAMA and Pb (II) was confirmed by FT-IR, XPS and ion-exchange behavior. Interestingly, CMC-PAMA showed high efficiency for separation of MB/methyl orange (MO) mixtures, low equilibrium swelling ratio (0.52 g·g-1) in distilled water, good stability and reusability. With those combined advantages, CMC-PAMA could find potential application in wastewater treatment.

Multi-triggered Supramolecular DNA/Bipyridinium Dithienylethene Hydrogels Driven by Light, Redox, and Chemical Stimuli for Shape-Memory and Self-Healing Applications.

Multi-triggered DNA/bipyridinium dithienylethene (DTE) hybrid carboxymethyl cellulose (CMC)-based hydrogels are introduced. DTE exhibits cyclic and reversible photoisomerization properties, switching between the closed state (DTEc), the electron acceptor, and the open isomer (DTEo) that lacks electron acceptor properties. One system introduces a dual stimuli-responsive hydrogel containing CMC chains modified with electron donor dopamine sites and self-complementary nucleic acids. In the presence of DTEc and the CMC scaffold, a stiff hydrogel is formed, cooperatively stabilized by dopamine/DTEc donor-acceptor interactions and by duplex nucleic acids. The cyclic and reversible formation and dissociation of the supramolecular donor-acceptor interactions, through light-induced photoisomerization of DTE, or via oxidation and subsequent reduction of the dopamine sites, leads to hydrogels of switchable stiffness. Another system introduces a stimuli-responsive hydrogel triggered by one of three alternative signals. The stiff, multi-triggered hydrogel consists of CMC chains cross-linked by dopamine/DTEc donor-acceptor interactions, and by supramolecular K+-stabilized G-quadruplexes. The G-quadruplexes are reversibly separated in the presence of 18-crown-6 ether and reformed upon the addition of K+. The stiff hydrogel undergoes reversible transitions between high-stiffness and low-stiffness states triggered by light, redox agents, or K+/crown ether. The hybrid donor-acceptor/G-quadruplex cross-linked hydrogel shows shape-memory and self-healing features. By using three different triggers and two alternative memory-codes, e.g., the dopamine/DTEc or the K+-stabilized G-quadruplexes, the guided shape-memory function of the hydrogel matrices is demonstrated.

Fabrication of acetylated carboxymethylcellulose coated hollow mesoporous silica hybrid nanoparticles for nucleolin targeted delivery to colon adenocarcinoma.

To efficiently deliver the chemotherapeutics to the tumor tissue and minimize the associated adverse effects, nucleolin targeted hybrid nanostructure based on hollow mesoporous silica nanoparticles (HMSNs) were fabricated. To provide the controlled, sustained drug release and enhance blood circulation, the surface of doxorubicin-encapsulated HMSNs were coated with acetylated carboxymethyl cellulose (Ac-CMC) and then covalently conjugated to AS1411 aptamer for guided drug delivery to nucleolin overexpressed cancerous cells. In vitro cellular uptake and cytotoxicity studies confirmed that AS1411 aptamer specifically targets nucleolin overexpressing MCF-7 and C26 cells. Moreover, the in vivo tumor inhibitory effect of AS1411 aptamer conjugated formulation demonstrated a superior therapeutic efficiency over non-targeted formulation and free doxorubicin. The current study might open a new insight to the development of targeted intelligent hybrid materials based on AcCMC-coated HMSNs with high loading capacity, smart characteristics and desirable anticancer potential.