A Complementary and Revised View on the N-Acylation of Chitosan with Hexanoyl Chloride

Abstract

The modification of the biobased polymer chitosan is a broad and widely studied field. Herein, an insight into the hydrophobization of low-molecular-weight chitosan by substitution of amino functionalities with hexanoyl chloride is reported. Thereby, the influence of the pH of the reaction media was investigated. Further, methods for the determination of the degree of substitution based on 1H-NMR, FTIR, and potentiometric titration were compared and discussed regarding their accuracy and precision. 1H-NMR was the most accurate method, while FTIR and the potentiometric titration, though precise and reproducible, underlie the influence of complete protonation and solubility issues. Additionally, the impact of the pH variation during the synthesis on the properties of the samples was investigated by Cd2+ sorption experiments. The adjusted pH values during the synthesis and, therefore, the obtained degrees of substitution possessed a strong impact on the adsorption properties of the final material.

Physicochemical Properties and Release Study of Antimetabolite-Incorporated Stearoyl Chitosan

“…Degree of substitution (DS) and DD refer to the degree of substitution and the degree of deacetylation, respectively . The value of DD was determined based on the ratio of A 1655 / A 3450 , as given in the equation below DD false( % false) = true( A 1655 A 3450 × 100 1.33 ) where A 1655 , A 3450 , and 1.33 correspond to absorbance values at 1655 cm –1 due to CO (amide I), band at 3450 cm –1 owing to the O–H band, and the assumption for fully deacetylated chitosan, respectively.…”

“…Degree of substitution (DS) and DD refer to the degree of substitution and the degree of deacetylation, respectively. 25 The value of DD was determined based on the ratio of A 1655 / A 3450 , as given in the equation below 41 i k j j j j j y…”

“…Chitosan and its derivatives have been extensively examined and deployed as efficient drug carriers owing to their interesting properties, such as nontoxicity, biocompatibility, biodegradability, bioadhesiveness, antimicrobial, and antifungal. − Studies pertaining to chitosan and its modified forms for drug delivery systems have demonstrated sustained release and colon-targeting delivery systems. − Drug carriers derived from acylated chitosan, ranging from short chain to long chain, have been widely utilized in many applications, including nanoparticle formulations and as coatings for liposomes. − The hydrophobicity increases proportionally with the length of the chain, thereby facilitating the encapsulation of the lipophilic medication.…”

Synthesis, characterization, and biological activities of folic acid conjugates with polyvinyl alcohol, chitosan, and cellulose

“…13 In addition, biobased CS was functionalized by substitution of its amino groups with hexanoyl chloride. 14 CS functionalized with liposomes provided potent applicability for nanomedicine design in the lung cancer treatment. 15 CS-based ligands conjugated with DNA, RNA, proteins, and therapeutic agents are promising carrier systems for targeted and non-viral gene delivery in treatment of breast cancer.…”

“…Modification of CS and sodium carboxymethylcellulose by magnetic molybdenum disulfide act as promising strategy for targeted drug delivery and photothermal tumor therapy 13 . In addition, biobased CS was functionalized by substitution of its amino groups with hexanoyl chloride 14 . CS functionalized with liposomes provided potent applicability for nanomedicine design in the lung cancer treatment 15 .…”