Carboxymethyl Groups Research Articles

Dextran and Its Derivatives: Biopolymer Additives for the Modulation of Vaterite CaCO3 Crystal Morphology and Adhesion to Cells

AbstractNowadays, a great demand for the development of novel drug delivery systems with high potential for bench‐to‐market transition attracts scientific attention toward materials that are already approved for biomedical use. Here, controlled fabrication of hybrid organic inorganic mesoporous crystals is realized in physiologically relevant conditions by co‐synthesis of vaterite CaCO3 in the presence of dextran (DEX) or its functional derivatives. The effects of DEX molecular weight and chemical structure on morphology, porosity, and stability of the hybrids are investigated. Molecular weight of DEX does not affect the crystal growth but leads to the partial blocking of crystal pores. Co‐synthesis of DEX functionalized with either carboxymethyl (CM) or diethylaminoethyl (DEAE) groups drastically increased crystal porosity without influencing crystal size. pH‐dependent vaterite‐to‐calcite recrystallization is significantly suppressed by inclusion of carboxymethyl‐dextran (CM‐DEX), making vaterite crystals stable in acidic medium, whereas the incorporation of diethylaminoethyl‐dextran (DEAE‐DEX) has no effect. The hybrids prepared with charged DEX derivatives possess stronger adhesion to normal human dermal fibroblasts: three times higher crystal adherence compared to pristine crystals. These results provide fundamental physical–chemical insights into the crystallization of DEX/vaterite hybrids and are discussed in view of the potential of these functional delivery carriers for biomedical and other applications.

Crystal structure determination, Hirshfeld surface, crystal void, inter-molecular inter-action energy analyses, as well as DFT and energy framework calculations of 2-(4-oxo-4,5-di-hydro-1H-pyra-zolo[3,4-d]pyrimidin-1-yl)acetic acid.

In the title mol-ecule, C7H6N4O3, the bicyclic ring system is planar with the carb-oxy-methyl group inclined by 81.05 (5)° to this plane. In the crystal, corrugated layers parallel to (010) are generated by N-H⋯O, O-H⋯N and C-H⋯O hydrogen-bonding inter-actions. The layers are associated through C-H⋯π(ring) inter-actions. A Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯O/O⋯H (34.8%), H⋯N/N⋯H (19.3%) and H⋯H (18.1%) inter-actions. The volume of the crystal voids and the percentage of free space were calculated to be 176.30 Å3 and 10.94%, showing that there is no large cavity in the crystal packing. Computational methods revealed O-H⋯N, N-H⋯O and C-H⋯O hydrogen-bonding energies of 76.3, 55.2, 32.8 and 19.1 kJ mol-1, respectively. Evaluations of the electrostatic, dispersion and total energy frameworks indicate that the stabilization is dominated via dispersion energy contributions. Moreover, the optimized mol-ecular structure, using density functional theory (DFT) at the B3LYP/6-311G(d,p) level, was compared with the experimentally determined one. The HOMO-LUMO energy gap was determined and the mol-ecular electrostatic potential (MEP) surface was calculated at the B3LYP/6-31G level to predict sites for electrophilic and nucleophilic attacks.

Chemical modification of nitrocellulose by grafting sodium carboxymethyl

Introducing deterrents improves the thermal stability of nitrocellulose of propellant surface, but is accompanied with inevitable problems, such as migration, residue, smoke flame, and so on. In this paper, sodium carboxymethyl function groups were chemically grafted to nitrocellulose molecular chains by reaction of denitration and following etherification, which provided thermal stability, flame suppression ion without deterrent migration. Various structure characterizations were conducted and confirmed the sodium carboxymethyl-nitrocellulose (CMNC) was prepared successfully. The number of sodium carboxymethyl groups linked to nitrocellulose chains was affected by both denitration and etherification. The results of thermal analysis showed that the thermal stability of CMNC improved with the increase of bearing sodium carboxymethyl groups and was better than that of original NC sample. Meanwhile, the thermal decomposition behaviors and decomposition products of CMNC are similar to that of NC at temperature of the first DTG peak Tmax and that of CMC at temperatures of the second DTG peak T2. This work provided a way for designing gun propellant with progressive burning, anti-migration and flame suppression simultaneously.

A Comparative Study of Different Methods for Cellulose Extraction from Lignocellulosic Wastes and Conversion into Carboxymethyl Cellulose

AbstractCarboxymethyl cellulose (CMC) is an appealing industrial chemical obtained by modification of cellulose with redundant applications in food, pharmaceuticals, paints, detergents and others. This report demonstrates the comparative study of potential of different lignocellulosic biomass by using five traditional methods to get white, pristine cellulose with higher percentage yield from waste, later, conversion of cellulose into its derivative i. e., carboxymethyl cellulose (CMC). Four raw materials comprising of wheat straw, sugarcane bagasse, rice straw and banana leaves were employed as an alternating source of cellulose. Sulfide method came out as a most viable delignification method, used to degrade all dewaxed wastes, efficiently. After cellulose extraction, substitution of hydroxyl groups of cellulose was executed by infusing cellulose with sodium hydroxide (NaOH) and monochloroacetic acid (MCA) in the presence of isopropanol as supporting medium. In this way, a variety of cellulose and CMC were obtained and verified with commercial samples of both products. Furthermore, characteristics of different CMC were checked including degree of substitution (DS), CMC content, moisture content, solubility and purity. The CMC from wheat straw showed the highest DS (2.1), solubility and yield. FTIR spectra confirmed the replacement of hydroxyl group with carboxymethyl group by indicating characteristic peak of carbonyl group (‐CO) at 1588 cm−1. In 1H NMR spectrum, plethora of peaks in the region 3–5 ppm indicated the derivatization of cellulose and 13C NMR confirmed the peaks of carbonyl carbons at 180 and 182 ppm. X‐ray diffraction (XRD) shows that the crystallinity of CMC has been reduced, significantly.

Synthesis of a bifunctional EDTA–carboxymethyl chitosan derivative and its potential as an adsorbent for the removal of Cu2+ ions from aqueous solutions

Chitosan is a well-studied biomaterial which has been widely used for environmental applications as an efficient natural polymer for the adsorption and removal of metal ions. Owing to its unique properties, chitosan shows good metal-binding behavior toward several different metal ions such as Cu2+, Zn2+, Cd2+, Ni2+, Co2+, and Ca2+. Chemical modifications with the introduction of functional groups have been carried out extensively and thereby producing various chitosan derivatives to increase the selectivity and adsorption capacity toward metal ions. The present work focuses on two such monofunctional derivatives, namely, carboxymethyl chitosan (CMC) and ethylenediaminetetraacetic acid chitosan (EDTA-CS) which have been recognized as excellent adsorbents for metal removal. The main objective of this study was to synthesize a new bifunctional chitosan derivative, namely, ethylenediaminetetraacetic acid–carboxymethyl chitosan (EDTA-CMC) by attaching both carboxymethyl and EDTA functional groups on the polymer backbone and thereby enhancing its metal-binding properties. The bifunctional derivative synthesis was conducted by combining the procedures of synthesis of CMC and EDTA-CS. Newly synthesized EDTA-CMC derivative was characterized by Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscope analysis, and thermogravimetric analysis. Adsorption properties of EDTA-CMC were investigated with Cu2+ ions which produced an adsorption capacity of 111.90 mg g−1 for 1000.0 mg/L and 12.20 mg g−1 for 10.00 mg/L Cu2+ solutions. The preliminary results revealed that EDTA-CMC is an effective adsorbent than CMC to remove Cu2+ in aqueous samples. The effects of pH, initial concentration, and mass of the adsorbent in the adsorption process were studied. Under the optimized parameters of an adsorbent dosage of 10.00 mg and pH 5.5, a comparable maximum adsorption capacity up to 112.44 mg g−1 was achieved with a 150.00 mg/L of Cu2+ solution. Furthermore, EDTA-CMC showed good adsorption performance even after five cycles of regeneration.

Identification of Pseudomonas asiatica subsp. bavariensis str. JM1 as the first Nε -carboxy(m)ethyllysine-degrading soil bacterium.

Thermal food processing leads to the formation of advanced glycation end products (AGE) such as Nε -carboxymethyllysine (CML). Accordingly, these non-canonical amino acids are an important part of the human diet. However, CML is only partially decomposed by our gut microbiota and up to 30% are excreted via faeces and, hence, enter the environment. In frame of this study, we isolated a soil bacterium that can grow on CML as well as its higher homologue Nε -carboxyethyllysine (CEL) as sole source of carbon. Bioinformatic analyses upon whole-genome sequencing revealed a subspecies of Pseudomonas asiatica, which we named 'bavariensis'. We performed a metabolite screening of P. asiatica subsp. bavariensis str. JM1 grown either on CML or CEL and identified N-carboxymethylaminopentanoic acid and N-carboxyethylaminopentanoic acid respectively. We further detected α-aminoadipate as intermediate in the metabolism of CML. These reaction products suggest two routes of degradation: While CEL seems to be predominantly processed from the α-C-atom, decomposition of CML can also be initiated with cleavage of the carboxymethyl group and under the release of acetate. Thus, our study provides novel insights into the metabolism of two important AGEs and how these are processed by environmental bacteria.

A comparative study of the nonlinear rheological properties of three different cellulose nanofibril suspensions

This study focused on the nonlinear rheological characterization of three types of cellulose nanofibril (CNF) suspensions under large amplitude oscillatory shear (LAOS) flow. Three different CNFs were produced, two by mechanical fibrillation alone under different conditions [here named microfibrillated cellulose (MFC) and U-CNF] and the other by mechanical fibrillation after carboxymethylation (CM-CNF). MFC and U-CNF had broad width distributions, whereas CM-CNF had narrower fibril width and width distribution due to the presence of charged carboxymethyl groups. Nonlinear stress responses of the prepared suspensions were analyzed using the sequence of physical processes method. All CNF suspensions exhibited intracycle rheological transitions composed of three physical processes: (1) structure recovery, (2) elastic deformation to early stage yielding, and (3) late-stage yielding. MFC and U-CNF suspensions exhibited similar rheological transitions overall. However, CM-CNF suspension had a higher network recovery rate within a shorter time and showed an additional yielding step due to the complex interplay between recovery and yielding dynamics. This result originated from complete nanofibrillation and charged functional groups on fibril surfaces. Rapid reformation of effective fibril–fibril contacts in CM-CNF suspension was attributed to electrostatic repulsions and complete nanosized lateral dimensions. In addition, excitation frequency was found to influence intracycle rheological transitions. A range of intracycle rheological transitions became narrower on increasing frequency because the time period for each transition was not enough under faster flow conditions. In particular, the characteristic yielding step of CM-CNF suspension disappeared on increasing frequency, which suggested that high-frequency excitation might be unfavorable for the nonlinear viscoelastic characterization of soft materials under LAOS flow.

The improvement of bactericidal properties and change of colour characteristics of knitted materials at using nanosilver and carboxymethyl starch

The availability of bactericidal knitted cotton fabrics by processing a biodegradable bactericidal nano composition containing nanoparticles of silver and Na-carboxymethyl starch is studied in this work. The nanocomposite based on Na-carboxymethyl starch and silver nanoparticles were successfully fixed on the surface of knitted cotton fabrics through the formation of links between carboxymethyl groups of carboxymethyl starch and nanosilver, as well as air interlacing between nano composition and material. The analysis of the change in the colour of knitted cotton fabrics after processing them with a solution of the nano composition of silver and Na-carboxymethyl starch showed the stability of the colouristic indicators of the colour during antibacterial treatment. Knitted cotton fabrics treated with the developed nano composition exhibit high antibacterial activity towards gram-positive fungal cultures of Bacillus subtilis, Staphylococcus aureus, and gram-negative Pseudomonas aeruginosa. Consistency of colour and the presence of bacteriostatic properties after repeated washing of knitted cotton fabrics confirms the stability of the antimicrobial properties of reusable fabrics.

Preparation, structure characterization of carboxymethylated schisandra polysaccharides and their intervention in immunotoxicity to polychlorinated biphenyls

Carboxymethylation is a well-known modification process for polysaccharides. To evaluated structural features and biological availability of carboxymethyl, carboxymethylated schisandra polysaccharides (CSP) was synthesized using an optimized chloroacetic acid /NaOH method. Optimal modification parameters were reaction temperature of 62.67 ℃, reaction time of 4.27 h, and 0.83 g chloroacetic acid. The main fraction of CSP (CSPP) was obtained by purification using DEAE-52 column. Chemical analysis indicated that CSPP contained carboxymethyl groups with a Mw of 1.698 × 104 g/mol and degree of substitution of 0.88 and composed of mannose, glucose and galactose at ratio of 1: 44.8: 3.7. Moreover, CSPP have improved water solubility (12.56 ± 0.04 mg/mL) and existed as a slight extended flexible chain. CSPP exhibited higher immunomodulating activities to polychlorinated biphenyl-126 (PCB126) -exposure mice than unmodified polysaccharide, as shown by improving PCB 126-induced reduction of body weight gain and atrophy of the immune organ, diminishing PCB126-induced inhibition of cytokines production and reversing damage of spleen caused by oxidative stress in PCB126-treated mice. It could be concluded that introduction of carboxymethyl groups to polysaccharide can alter its physicochemical characteristic to enhance its immunoregulatory activity. This study suggested that CSPP potentially serve as an effective nutritional intervention agent to reverse the PCB126-induced immunosuppression.

Absorbable Hemostatic Material with High Water Absorption Based on Polysaccharide

An absorbable hemostatic material based on polysaccharide was prepared. The concentration of blood cells and coagulation factors was increased by reducing the water content in the blood, so as to reduce the coagulation time and achieve the purpose of rapid hemostasis. The specific surface area of starch was increased by using hydrochloric acid to hydrolyze potato starch, which made it easier to combine with α-amylase and increased the degradation rate. Starch was crosslinked into microspheres by crosslinking agent, which made the particle size uniform and greatly improved the water absorption. The surface modification of crosslinked starch microspheres with carboxymethyl group can further improve the water absorption of hemostatic materials. The results showed that the water absorption rate of our hemostatic material was more than 800%, and the average hemostatic time in the animal model was 138.7s. Compared with the imported products on the market, our hemostatic material have better hemostatic performance.

Encapsulation of Curcumin in a Ternary Nanocomplex Prepared with Carboxymethyl Short Linear Glucan-Sodium-Caseinate-Pectin Via Electrostatic Interactions.

This work chemically modified short linear glucan (SLG) by introducing a surface carboxymethyl group to obtain carboxymethylated SLG (CMSLG), then prepared CMSLG-based ternary nanocomplex particles based on electrostatic interactions with sodium-caseinate (NaCas) and pectin. These nanocomplex particles are homogeneous, generally exhibiting sizes of<200nm with spherical shape and negative surface charge. In addition, the results showed the increase in both the mass ratio of CMSLG and NaCas and the synthesis temperature can improve the colloidal stability of nanocomplex particles when they are exposed to simulated gastrointestinal fluids containing digestive enzymes. Moreover, nanocomplex particles have an exceptional capability to encapsulate curcumin, and this encapsulation efficiency increased as the mass ratios of CMSLG and NaCas were increased. The study also investigated the antioxidant activity and in vitro release properties of curcumin encapsulated by nanocomplex particles and found that CMSLG/NaCas/pectin had improved higher ABTS radical scavenging capacity and allowed for the controlled, sustained release of curcumin in simulated gastrointestinal fluid within 6hours. Thus, this study provides new insights into the design of a CMSLG-based ternary nanocomplex and its use as a potential oral delivery system for lipophilic bioactive compounds. PRACTICAL APPLICATION: Curcumin, as a sort of natural polyphenolic compound, has many physiologic functions such as anti-oxidation, anticancer, and prevention of Alzheimer's disease. However, the application of the curcumin has been limited by its poor water solubility and unstable physicochemical property. To solve this problem, the nanotechnology has been used to prepare the nano-delivery carriers for curcumin. This work prepared a ternary nanoparticle based on the carboxymethyl short linear glucan, sodium-caseinate, and pectin. The ternary nanoparticle can achieve a higher encapsulation efficiency for curcumin. In addition, the ternary nanoparticle can enhance the ABTS radical scavenging capacity and provided control and sustained release of curcumin in the simulated gastrointestinal fluid.

Facile Post-Carboxymethylation of Cellulose Nanofiber Surfaces for Enhanced Water Dispersibility.

To improve the water dispersibility of cellulose nanofibers without deteriorating the physical properties, it is necessary to develop methods that can selectively modify fiber surfaces. Herein, the reaction conditions for carboxymethylation of the surface of nanofibrillated bacterial cellulose were optimized using chloroacetic acid as an etherification agent. Carboxymethylation in a high-concentration alkaline solution (>5 wt %) in the presence of isopropanol caused the mercerization and carboxymethylation of not only the nanofiber surface but also the cellulose crystals within the nanofiber, resulting in nanofiber swelling and an increase in fiber width. In contrast, with a dilute alkaline aqueous solution (3 wt %), the nanofiber surface was successfully carboxymethylated without changing the inner structure. Furthermore, the morphology was not affected by the carboxymethylation reaction, and no fiber swelling occurred under these reaction conditions. When the substitution reaction proceeded only on the nanofiber surface, the maximum degree of substitution (i.e., the average number of carboxymethyl groups substituted per anhydroglucose residue in cellulose) was 0.091. After surface modification, the nanofibers became more negatively charged, which improved the dispersibility in water through electrostatic repulsion, resulting in a drastic increase in the transparency of the nanofiber dispersion. This method provides a general approach for the surface modification of cellulose nanofibers to increase water dispersibility.

Screening the synergy of sodium dodecylbenzenesulfonate and carboxymethyl cellulose for surfactant-polymer flooding

Carboxymethyl cellulose (CMC) has emerged in oil and gas industries as a superior substitution to the conventional HPAM and xanthan gum (XG) for high viscosity polymer flooding application. In this study, the combined effect of conventional surfactant, sodium dodecylbenzenesulfonate (SDBS) and CMC for potential surfactant-polymer (SP) flooding in enhanced oil recovery (EOR) has been investigated. Thereafter, SDBS – CMC interaction and the functional groups present in CMC were appropriately identified. The presence of various C–O bonds signifies the existence of carboxymethyl group which greatly influence the rheological properties of CMC solution. The behaviour of SDBS–CMC was characterized by their viscosity, shear rate, solubilization, wettability, and surface tension. Tertiary flooding utilizing SDBS-CMC was performed and compared to commercial SDBS-XG SP flooding. The results indicate several SDBS-CMC combinations are favourable for EOR application. Solution viscosity shows direct relationship with CMC concentrations. Consequently, at any given SDBS concentrations, significant increment was observed at 0.3 wt% and above. However, the trend displayed inconclusive relation to SDBS fractions. Majority of the SDBS-CMC combinations generate Winsor III emulsions particularly at CMC of 0.2 and 0.3 wt%, while Type II were observed in few combinations. Increasing CMC concentrations increased the contact angle, while gradual reductions were observed with SDBS concentrations. The gradual reduction in surface tension was highly influenced by the addition of CMC rather than SDBS. A novel combination of 0.3 wt% SDBS and 0.4 wt% CMC possessed an encouraging criterion in term of viscosity, solubilization, and surface tension reduction for EOR application. Flooding experiment from several SDBS-CMC combinations proved to recover additional oil ranging 16.4–20.2% of oil initially in place (OIIP). The trend in incremental oil recovery is similar to that of when utilising SDBS-XG.

Fabrication, Structure and Functional Characterizations of pH-Responsive Hydrogels Derived from Phytoglycogen.

The pH-responsive hydrogels were obtained through successive carboxymethylation and phosphorylase elongatation of phytoglycogen and their structure and functional characterizations were investigated. Phytoglycogen (PG) was first carboxymethylated to obtain carboxymethyl phytoglycogen (CM-PG) with degree of substitution (DS) at 0.15, 0.25, 0.30, and 0.40, respectively. Iodine staining and X-ray diffraction analysis suggested that the linear glucan chains were successfully phosphorylase-elongated from the non-reducing ends at the CM-PG surface and assembled into the double helical segments, leading to formation of the hydrogel. The DS of CM-PG significantly influenced elongation of glucan chains. Specifically, fewer glucan chains were elongated for CM-PG with higher DS and the final glucan chains were shorter, resulting in lower gelation rate of chain-elongated CM-PG and lower firmness of the corresponding hydrogels. Scanning electron microscope observed that the hydrogels exhibited a porous and interconnected morphology. The swelling ratio and volume of hydrogels was low at pH 3–5 and then became larger at pH 6–8 due to electrostatic repulsion resulting from deprotonated carboxymethyl groups. Particularly, the hydrogel prepared from chain-elongated CM-PG (DS = 0.25) showed the highest sensitivity to pH. These results suggested that phosphorylase-treated CM-PG formed the pH-responsive hydrogel and that the elongation degree and the properties of hydrogels depended on the carboxymethylation degree. Thus, it was inferred that these hydrogels was a potential carrier system of bioactive substances for their targeted releasing in small intestine.

Structure–activity relationship study of hydroxyethylamine isostere and P1′ site structure of peptide mimetic BACE1 inhibitors

An aromatic substituent has been introduced into a known hydroxyethylamine (HEA)-type BACE1 inhibitor containing the superior substrate sequence to enhance inhibitory activity. The HEA-type isosteres bearing different hydroxyl group and methyl group configurations were prepared through a branched synthesis approach using intra- and inter-molecular epoxide opening reactions. The effect of their configuration was evaluated, showing that an R-configuration improved the inhibitory activity, while introduction of a methyl group on the isostere decreased the activity. Based on the non-substituted isostere with an R-configuration, 21 derivatives containing various substituents at the P1′ site were synthesized. Our evaluation of the derivatives showed that the structure of the P1′ site had a clear effect on activity, and highly potent inhibitor 40g, which showed sub-micromolar activity against recombinant BACE1 (rBACE1), was identified. The docking simulation of 40g with rBACE1 suggested that a carboxymethyl group at the para-position of the P1′ benzene ring interacted with Lys285 in the S1′ pocket.

Sulfonated and Carboxymethylated β-Glucan Derivatives with Inhibitory Activity against Herpes and Dengue Viruses.

The infection of mammalian cells by enveloped viruses is triggered by the interaction of viral envelope glycoproteins with the glycosaminoglycan, heparan sulfate. By mimicking this carbohydrate, some anionic polysaccharides can block this interaction and inhibit viral entry and infection. As heparan sulfate carries both carboxyl and sulfate groups, this work focused on the derivatization of a (1→3)(1→6)-β-D-glucan, botryosphaeran, with these negatively-charged groups in an attempt to improve its antiviral activity. Carboxyl and sulfonate groups were introduced by carboxymethylation and sulfonylation reactions, respectively. Three derivatives with the same degree of carboxymethylation (0.9) and different degrees of sulfonation (0.1; 0.2; 0.4) were obtained. All derivatives were chemically characterized and evaluated for their antiviral activity against herpes (HSV-1, strains KOS and AR) and dengue (DENV-2) viruses. Carboxymethylated botryosphaeran did not inhibit the viruses, while all sulfonated-carboxymethylated derivatives were able to inhibit HSV-1. DENV-2 was inhibited only by one of these derivatives with an intermediate degree of sulfonation (0.2), demonstrating that the dengue virus is more resistant to anionic β-D-glucans than the Herpes simplex virus. By comparison with a previous study on the antiviral activity of sulfonated botryosphaerans, we conclude that the presence of carboxymethyl groups might have a detrimental effect on antiviral activity.

Thermosensitive Poloxamer-graft-Carboxymethyl Pullulan: A Potential Injectable Hydrogel for Drug Delivery.

A thermosensitive copolymer composed of amphiphilic triblock copolymer, poloxamer 407, grafted on hydrophilic pullulan with pendant carboxymethyl groups (CMP) was prepared and characterized. The structure of the new copolymer was assessed by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (1H NMR) spectroscopy. The content of the poloxamer in the grafted copolymer was 83.8% (w/w). The effect of the copolymer concentration on the gelation behavior was analyzed by the vertical method and rheological tests; the gel phase of the copolymer occurred at a lower concentration (11%, w/v) as compared with poloxamer (18%, w/v). The starting gelation time under the simulated physiological conditions (phosphate buffer with a pH of 7.4, at 37 °C) was sensitive on the rest temperature before the test, this being 990 s and 280 s after 24 h rest at 4 °C and 20 °C, respectively. The rheological tests evidenced a high elasticity and excellent ability of the copolymer to recover the initial structure after the removal of the applied force or external stimuli. Moreover, the hydrogel has proved a sustained release of amoxicillin (taken as a model drug) over 168 h. Taken together, the results clearly indicate that this copolymer can be used as an injectable hydrogel.

Acylated carboxymethyl chitosan grafted with MPEG-1900 as a high-efficiency demulsifier for O/W crude oil emulsions

In this work, due to its excellent adsorption performance, biodegradability, and low toxicity, chitosan was used as the raw material to synthesize a series of new oil-in-water (O/W) type crude oil demulsifiers. First, an acyl group was introduced onto the chitosan molecule. Then, sodium chloroacetate was used as a carboxymethylation reagent to introduce a carboxymethyl group into the acylated chitosan. Furthermore, polyethylene glycol monomethyl ether with an average molecular weight of 1900 (MPEG-1900) was used to react with acylated carboxymethyl chitosan to synthesize chitosan-based O/W type demulsifiers. The molecular structures of the synthetic chitosan derivatives were characterized using Fourier-transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance techniques. The results showed that the surface tension decreased with an increase in the concentration of polysaccharide demulsifiers, which included MPEG-1900-A4CMC, MPEG-1900-A6CMC, and MPEG-1900-A8CMC. The demulsification efficiency of these synthetic demulsifiers reached a maximum over 100 min at a concentration of 200 ppm at 50 °C. The as-synthesized chitosan derivatives showed good demulsification performance.

Development of Aldehyde Hyaluronic Acid - N,O-Carboxymethyl Chitosan based Hydrogel for Intraperitoneal Antiadhesion Application

Intraperitoneal adhesion is a serious case that often occurs with a prevalence of 90-97 % after undergoing gynecological surgery and laparotomy. This study aims are to characterized the hydrogel and identified the optimal composition of Hyaluronic acid (HA) - N, O-carboxymethyl chitosan (NOCC) as an anti-adhesion biomaterial barrier. The synthesis method involved firstly the synthesis of aldehyde derivative of hyaluronic acid (AHA) and also the conversion of chitosan into its derivative, N,O-carboxymethyl chitosan. These two compounds were mixed in various compositions and crosslinked to form N, O-carboxymethyl chitosan (NOCC) /AHA. Fourier-transform infrared spectroscopy has confirmed that the functional groups found -C = O stretching at 1644 cm-1 indicating the hyaluronic acid and carboxymethyl group (-CH2COOH) in 1380 cm-1 which indicate the presence of chitosan. The crosslink is evidenced by the group C = N stretching at a wavenumber of about 1630 cm-1. The best composition of intraperitoneal anti-adhesion is the ratio of hyaluronic acid: chitosan at 30:10 mg/ml. The swelling test is showed a swelling ratio of around 211.8 % in accordance with the standard as intraperitoneal anti-adhesion. Hydrogel has a degradation rate up to 86.87 % on day 10, and this is in accordance with the standard as intraperitoneal anti-adhesion. Cytotoxicity assay showed that hydrogel was nontoxic with a percentage of 92.9 % cell viability. The newly developed hyaluronic acid-carboxymethyl chitosan has characteristics that conform to the criteria of an intraperitoneal anti-adhesion.

Effects of various types of cellulose nanofibers on the physical properties of the CNF-based films

Cellulose-based films using three different types of cellulose nanofibers (CNFs), carboxymethylated CNF (CNFCM), enzyme-treated CNF (CNFENZ), TEMPO-oxidized CNF (CNFTEMPO), and sodium carboxymethyl cellulose (CMC) were prepared using a solution casting method, and their film properties were characterized to test the effect of CNF types. FE-SEM image showed the densely packed fibers in the film with different fiber shapes depending on the CNF types, while the AFM image showed the roughness of the films. The CNFTEMPO film was as transparent as the CMC film, while the other CNF films were translucent. The CNF films also showed different crystalline structures depending on the CNF types, so the film properties were greatly influenced by the cellulose crystallinity index (CI). The CNFENZ film with the highest CI showed higher thermal stability and water vapor barrier properties than the other films. Also, the water vapor permeability of CNF films was significantly lower than the CMC film. The carboxylate and carboxymethyl groups in the CNFTEMPO and CNFCM films increased the tensile strength, which was about two times higher than that of the CNFENZ and CMC films. The CNF film properties depended on the CNF type and were comparable or superior to the CMC film.