Carboxymethylation of dextran in aqueous alcohol as the first step of the preparation of derivatized dextrans

Abstract

Carboxymethyldextrans (CMD) with a degree of substitution of carboxymethyl groups DS > 0.9 are precursors for the synthesis of derivatized dextrans termed CMDBS, which present heparin‐like biological properties. Syntheses of CMD in water/organic solvent mixtures using monochloroacetic acid (MCA) and strong alkaline conditions allowed to obtain highly substituted CMD with good reproducibility and high yields. The influences of, respectively, individual concentrations of reactants, composition and temperature of reaction medium, and allowed reaction time have been examined. The most favorable conditions for dextran carboxymethylation were obtained with 3.8 M NaOH and a [MCA]/[dextran] ratio of 2.5, allowed to react at 60°C for 90 min, in a reaction medium consisting of a tert‐butanol/water (alternatively isopropanol/water) 85 : 15 (v/v) mixture. A DS of about 1.0 was obtained in one step, as compared to a DS less than 0.6 when using aqueous conditions. Improvements on overall CMD substitution levels (up to DS of 1.47) were achieved by merely repeating the reaction i. e. using the CMD products of the first reaction as substrate in the second.

Effect of surface charge on the colloidal stability and in vitro uptake of carboxymethyl dextran-coated iron oxide nanoparticles

“…CMDx were prepared by a carboxymethylation reaction, where monochloro acetic acid reacted with dextran and sodium hydroxide (Chaubet et al 1995; Huynh and Jozefonvicz 1998). Sodium hydroxide concentrations between 2 and 3 M were used to obtain different degrees of carboxymethylation.…”

“…After the carboxymethylation reaction, the modified dextrans are in the form of a carboxylate sodium salt (−CH 2 COONa) (Huynh and Jozefonvicz 1998). An acid wash was used to obtain the free acid form (−CH 2 COOH).…”

Magnetic poly(glycidyl methacrylate) microspheres containing maghemite prepared by emulsion polymerization

“…(Carboxymethyl)dextran (CM-dextran) was obtained by the reaction of dextran T 40 (M w ¼ 33; 000; M w =M n ¼ 1:4; from Dextran Products Lmt., Scarborough, Canada) with chloroacetic acid [11]. Na salt of poly(oxyethylene) alkylaryl ether sulfate (Disponil s AES 60) was from Henkel, Du¨sseldorf, Germany, 25% ammonium hydroxide solution from Lachema, Neratovice, Czech Republic, sodium hypochlorite solution was from Bochemie, Bohumı´n, Czech Republic, 4,4 0 -azobis(4-cyanovaleric acid) (ACVA) and all other reagent grade chemicals were purchased from Aldrich and used as received.…”

Hypericin-bearing magnetic iron oxide nanoparticles for selective drug delivery in photodynamic therapy

“…21,22 Additionally, the hydroxyl groups of this polymer can be used to add various functionalities, which can then be further used to link the photosensitizer (PS), in our case, hypericin. 23 Hypericin, a naturally occurring PS, is an essential component of the plant Hypericum perforatum, also known as St John's wort. Besides its natural extraction, hypericin can also be synthesized as described by Karioti and Bilia.…”