Degree Of Carboxymethyl Substitution Research Articles

Effects of Raw Material Source on the Properties of CMC Composite Films.

Sodium carboxymethyl cellulose (CMC) can be derived from a variety of cellulosic materials and is widely used in petroleum mining, construction, paper making, and packaging. CMCs can be derived from many sources with the final properties reflecting the characteristics of the original lignocellulosic matrix as well as the subsequent separation steps that affect the degree of carboxy methyl substitution on the cellulose hydroxyls. While a large percentage of CMCs is derived from wood pulp, many other plant sources may produce more attractive properties for specific applications. The effects of five plant sources on the resulting properties of CMC and CMC/sodium alginate/glycerol composite films were studied. The degree of substitution and resulting tensile strength in leaf-derived CMC was from 0.87 to 0.89 and from 15.81 to 16.35 MPa, respectively, while the degree of substitution and resulting tensile strength in wooden materials-derived CMC were from 1.08 to 1.17 and from 26.08 to 28.97 MPa, respectively. Thus, the degree of substitution and resulting tensile strength tended to be 20% lower in leaf-derived CMCs compared to those prepared from wood or bamboo. Microstructures of bamboo cellulose, bamboo CMC powder, and bamboo leaf CMC composites’ films all differed from pine-derived material, but plant source had no noticeable effect on the X-ray diffraction characteristics, Fourier transform infrared spectroscopy spectra, or pyrolysis properties of CMC or composites films. The results highlighted the potential for using plant source as a tool for varying CMC properties for specific applications.

Physicochemical characteristics of thermo-responsive gelatin membranes containing carboxymethyl chitosan and poly(N-isopropylacrylamide-co-acrylic acid)

Gelatin has many superior biological properties and can absorb a large volume of water to form hydrogels, making it a promising material for skin wound care. In this study, gel membranes were prepared based on gelatin and added with different amounts of the synthesized carboxymethyl chitosan (CMCS) and poly(N-isopropylacrylamide-co-acrylic acid) (P(NI-co-AA)) copolymer for providing antibacterial and thermo-responsive properties, respectively. The synthesized CMCS had a degree of carboxymethyl substitution at 0.77 and the P(NI-co-AA) had an AA content of 5.7 mol %. Both CMCS and P(NI-co-AA) had carboxylate groups that could further provide ionic-crosslinking sites for the membranes. Though the P(NI-co-AA) copolymer had a higher phase transition temperature than poly(N-isopropylacrylamide) (PNIPAAm) owing to its hydrophilic carboxylate groups, the prepared gelatin/CMCS/P(NI-co-AA) membranes had similar phase transition temperatures to the PNIPAAm at around 30.5 − 32.4 °C because of ionic crosslinking. Moreover, the equilibrium swelling ratio and water vapor transmission rate of the gel membranes were in the range of 769 − 1226% and 1678 − 2496 g/m2- day, respectively. These membranes could promote cell proliferation of human keratinocytes (HaCaT) and mouse fibroblasts (L-929), indicating they were non-toxic to the cells. They also had antimicrobial properties against S. aureus and E. coli, where the antibacterial efficacy increased with increasing the CMCS content. These hydrogel membranes had good biocompatibility, suitable swelling ratio and water vapor transmission rate, antibacterial and thermo-responsive properties. Therefore, they have potential to be applied as functional wound dressing material.

Synthesis, characterization and fabrication of sodium carboxymethyl-okra-gum-grafted-polymethacrylamide into sustained release tablet matrix

The objective of the present study was to modify okra gum (Abelmoschus esculentus) by carboxymethylation and subsequent graft-copolymerization, characterize and fabricate into sustained-release tablet matrix. Firstly, okra gum was carboxymethylated using sodium hydroxide and monochloroacetic acid followed by grafting with polymethacrylamide employing synergistic combination of free-radical-initiator and microwave-irradiation. The FTIR, NMR, elemental analysis and viscosity study corroborate the formation of sodium-carboxymethyl-okra gum–grafted-polymethacrylamide copolymer (SCMOG-g-PMA). The maximum degree of carboxymethyl-substitution (DCS) and % grafting (%G) were found to be 0.604 ± 0.011 and 644.1, respectively. Water-uptake-capacity was found to increase by 3.5 fold. The tablet formulation of diclofenac sodium with SCMOG-g-PMA (DCS 0.604 and 423.4% G) showed to exhibit excellent sustained-release capacity with 90% drug-release at 11.7 h and similarity-factor of 72.0. The toxicity and biodegradability study also exhibited the bio-compatible and biodegradable nature of the copolymer, which might make the copolymer suitable for sustained-release drug delivery systems as smart semi-synthetic biopolymer.

Carboxymethyl modification of Cassia obtusifolia galactomannan and its evaluation as sustained release carrier

Carboxymethylation of Cassia obtusifolia galactomannan was carried out by Williamsons synthesis. Modification of galactomannan was confirmed by Fourier-transform infrared and 1H-Nuclear magnetic resonance spectroscopy. The degree of carboxymethyl substitution was found to be 1.69. Carboxymethylation was observed to increase the powder flow, solubility and swelling, while decrease the viscosity and alter the compression characteristics from elastic to plastic. The results of X-ray diffraction and scanning electron microscopy studies indicated increase in degree of crystallinity. The modified gum was used for preparing diclofenac sodium-loaded, Ca2+-gelled beads which were coated with gastroresistant Eudragit-L100. The formulation of beads was optimized using central composite experimental design. The optimal formulation of beads contained carboxymethylated Cassia galactomannan-2.85%,w/v and calcium chloride −15%,w/v, which showed yield −185.4%, entrapment-95.41% and release of 93.32% of diclofenac over 24 h. The release of diclofenac followed first-order kinetics by Super case-II transport. Thus, carboxymethyl Cassia galactomannan appears suitable for sustained drug delivery.

Thiolated and carboxymethylated Cassia obtusifolia seed mucilage as novel excipient for drug delivery: development and characterisation

ABSTRACT The objective of present work was to isolate the mucilage as polysaccharide from the seeds of Cassia obtustifolia and to modify the isolated polysaccharide chemically by thiolation and carboxymethylation to develop novel excipient for drug delivery application. The attempts were made to enhance mucoadhesive potential of Cassia obtustifolia seed mucilage by thiolation and to reduce the disintegration time in prepared tablets by carboxymethylation. Thiolation of Cassia obtustifolia seed mucilage was achieved by esterification with thioglycolic acid and thiol group content was measured by using Ellman’s reagent, whereas carboxymethylation was archived by etherification of Cassia obtusifolia seed mucilage with monochloroacetic acid and the degree of carboxymethyl substitution was determined by titrimetric method. Thiolation and carboxymethylation of Cassia mucilage was confirmed by, Fourier transform infrared spectroscopy (FT-IR), 1H NMR spectroscopy, differential scanning calorimeter (DSC thermogram) and by Zeta potential measurement. The findings demonstrated that there is significant improvement in bioadhesive and disintegration property via respective chemical modifications such as thiolation and carboxymethylation.

Improving Conductivity Performance of Chitosan by Carboxymethylation Reaction: Synthesis and Characterization

Chitosan has been applied widely in electrical energy storage purposes like battery and fuel cell, as in electrolyte. This research purposed on improving compatibility chitosan as material for electrical energy storage by chemical reaction. Carboxymethylation reaction performed on chitosan to add carboxymethyl groups in either hydroxyl or amine sites or both. The substitution result could effect by optimizing in the ratio of reactants and reaction condition. Carboxymethylation process on chitosan will confirm by FTIR analysis and degree of carboxymethyl substitution can be calculated from 1H NMR. Its ionic conductivity will calculate from EIS. The highest degree of substitution obtained at 64.64%. This reaction had the ratio of chitosan:monochloroacetic acid about 1:6 (m/m) and was reacted in reflux system at 65°C. EIS analysis showed improvement of carboxymethyl chitosan’s conductivity where pure chitosan had 2.7 x 10-6 Scm-1 and CMC-IV had 2.7 x 10-5 Scm-1 at room temperature.

Carboxymethyl sesbania gum: Synthesis, characterization and evaluation for drug delivery

In the present study, carboxymethyl Sesbania gum was synthesized and evaluated for drug delivery. Carboxymethylation was carried out by reacting with monochloroacetic acid under alkaline conditions. Modification of the gum was confirmed by Fourier-transform infrared spectroscopy. The degree of carboxymethyl substitution was determined to be 1.3. Carboxymethylation improved the flow properties, increased the degree of crystallinity and changed the compression behaviour from elastic to plastic. Further, the interaction between the modified gum and Ca2+-ions was optimized employing a 3-factor, 3-level central composite experimental design to prepare mucoadhesive sustained release beads using metformin hydrochloride as the model drug. The optimal calculated parameters were- concentrations of carboxymethyl Sesbania gum-2.5%(w/v), metformin hydrochloride- 50%(w/w) and calcium chloride- 15%(w/v), which provided beads with%yield of 160 and entrapment efficiency of 39.3%. The optimized batch of beads released, 68% of metformin over 12h, following the Higuchi’s release kinetics with the mechanism of release being diffusion through the matrix.

Physicochemical, in vitro digestibility and functional properties of carboxymethyl rice starch cross-linked with epichlorohydrin

Cross-linked carboxymethyl rice starches (CL-CMRSs) were prepared from reactions between native rice starch and varied concentrations (0.1–15%w/w, M-0.1 to M-15) of epichlorohydrin (ECH) in a simultaneous carboxymethylation-crosslinking reaction setup using methanol as the solvent. The degree of carboxymethyl substitution was between 0.24 and 0.28, while apparent amylose contents were lowered due to modification. SEM images showed minor change on the granule surface, while XRD profiles indicated slight loss of crystallinity. DSC thermograms revealed no transition peak in all treated samples. The water uptake (WU), swelling volume (SV) and free swelling capacity (FSC) of CL-CMRSs increased significantly as a result of the modification, while swelling of CMRSs cross-linked with 2% (M-2) and 3% (M-3) ECH yielded FSC values and WU values that were much greater than those of native starches and were comparable to that of Explotab®. All modified starch samples showed increased amount of rapidly digestible starch (RDS), while cross-linking with 5–7.5% ECH raised the resistant starch (RS) content, compared to native starch. M-2 also showed promising results in tablet disintegration test. ECH–CL–CMRSs could potentially be used as an excipient in pharmaceutical and food/food supplement products.

Evaluation of carboxymethyl gellan gum as a mucoadhesive polymer

The study was conducted to evaluate carboxymethyl gellan gum as bioadhesive polymer for drug delivery applications. Gellan gum was carboxymethylated by reacting it with monochloroacetic acid. Degree of carboxymethyl substitution was found to be 1.18. Further, carboxymethylation of gellan gum was found to increase its degree of crystallinity, surface roughness and diminish the cation-induced gelation. On comparative evaluation carboxymethyl gellan gum showed 2.71-fold higher mucoadhesive strength than gellan gum. Evaluation of ex vivo ocular tolerance using chorioallantoic membrane of hen's egg and cytotoxicity screening on Vero cells using resazurin assay revealed that caroboxymethyl gellan gum is non-irritant and biocompatible. Ionotiropically gelled beads of carboxymethyl gellan gum formulated using metformin as the model drug and calcium chloride as the cross-linking agent showed ex vivo bioadhesion of 100% over 24h. Further, it was observed that carboxymethyl gellan gum beads released metformin at a rate faster than gellan gum.

Preparation and characterization of carboxymethyl polyvinyl alcohol–graphite nanosheet composites

AbstractCarboxymethyl polyvinyl alcohol (CMPVA) was prepared by introducing carboxymethyl groups to polyvinyl alcohol (PVA) with chloroacetic acid. Graphite nanosheets (NanoG) were obtained by treating expandable graphite at a high temperature in a muffle furnace, and then sonicating it in an aqueous ethyl alcohol solution. Nanocomposites of CMPVA with NanoG were prepared by dispersing NanoG in a CMPVA aqueous solution with the aid of sonication and then casted on plastic film to remove water. Carboxymethyl groups were proved to be linked to PVA by Fourier transform infrared (FTIR) spectra and the degree of carboxymethyl substitution on the PVA was 2.77% determined by conductometric titration. Experimental results show that carboxylate anions in introduced carboxymethyl groups facilitate the dispersal of NanoG with positive charges in the CMPVA solution. The CMPVA matrix was detected by X‐ray diffraction (XRD) and FTIR spectra to be less crystal, into which NanoG tend to disperse. Scanning electron microscopy was used to characterize the structure of the graphite and morphology of the composites to prove that NanoG was 40–70 nm thick. The percolation threshold of CMPVA/NanoG composites at room temperature was as low as 0.80 wt%. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers