Quaternization of N-aryl chitosan derivatives: synthesis, characterization, and antibacterial activity

Efficiency of chitosans for the treatment of papermaking process water by dissolved air flotation

“…The two quaternary derivatives (Quat.5 and Quat.10) were prepared from the low molecular weigth chitosan (Ch.LMW) using N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride (Quat-188) as the quaternizing agent. They were prepared following the method described in [16] and two weight ratios chitosan:Quat-188 were used; one is 1:5 for Quat.5 and the other is 1:10 for Quat.10, in order to obtain two different quaternization degrees (Table 2). Anionic bentonite microparticles (Hydrocol ® OT) were supplied by Ciba Specialty Chemicals (Switzerland) and were tested together with the native chitosans.…”

“…However, this charge density is pH dependent where at neutral to basic conditions, chitosan loses its charge and precipitates from solution making it unusable. For these applications, quaternization is an alternative path to produce water-soluble chitosan derivatives with a wide operational pH range including neutral and slight basic conditions which are common in papermaking operations due to a permanent positive charge on the polymer backbone [16][17][18][19]. In addition, this would avoid the use of carboxylic acid solutions (such as acetic acid), which could increase organics content of treated waters, or inorganic acid solutions (such as chlorhydric acid) for preparing chitosans [20][21].…”

Biomedical Activity of Chitin/Chitosan Based Materials—Influence of Physicochemical Properties Apart from Molecular Weight and Degree of N-Acetylation

“…It was observed that N-quaternization was mainly responsible for the antibacterial effects at pH 7.2, whereas it did not contribute to the antibacterial activity under acidic conditions. Sajomsang et al [105] synthesized 17 derivatives of chitosan consisting of a variety of N-aryl substituents (ES parameter), and each of the derivatives was further quaternized using the quaternizing agent that reacted with either the primary amino or hydroxyl groups of the glucosamine residue of chitosan. All the quaternized derivatives of chitosan showed antibacterial activity, but derivatives with ES values higher than 20% exhibited low antibacterial activity.…”

Interaction of O-acylated chitosans with biomembrane models: Probing the effects from hydrophobic interactions and hydrogen bonding

“…This activity depends on various parameters, including the average degree of acetylation and molecular weight of the chitosans [5][6][7][8], which may be controlled with variable degrees of accuracy. Most significantly, chitosans may also be derivatized with incorporation of acyl and alkyl chains [9,10], and these derivatives have been proven to be even more efficient than their parent chitosans [11]. This is the case, for example, of the antimicrobial activity of chitosan derivatives against bacteria (Gram positive or negative) [10,12,[14][15][16][17], fungi [13] or both [18][19][20].…”

“…Most significantly, chitosans may also be derivatized with incorporation of acyl and alkyl chains [9,10], and these derivatives have been proven to be even more efficient than their parent chitosans [11]. This is the case, for example, of the antimicrobial activity of chitosan derivatives against bacteria (Gram positive or negative) [10,12,[14][15][16][17], fungi [13] or both [18][19][20]. The reasons for the enhanced action of the derivatized chitosans are not known in detail, but they must be related to the damage or breaking of cell membranes resulting from the interplay between ionic and hydrophobic interactions.…”