Determining the Deacetylation Degree of Chitosan: Opportunities To Learn Instrumental Techniques

Abstract

To enhance critical thinking and problem-solving skills, a project-based learning (PBL) approach for "Instrumental Techniques" courses in undergraduate physical chemistry was specifically developed for a pharmacy bachelor degree program. The starting point of this PBL was an open-ended question that is close to the student scientist's interest and related to this lab: "How can we determine the deacetylation degree of chitosan?" Chitosan is a polysaccharide used in a broad range of pharmacy applications because of its unique properties. Many of these properties derive from the presence of primary amino groups (−NH 2 ) in its structure. These −NH 2 groups are usually formed by the deacetylation of chitin. For this reason, a proper quantification of the deacetylation degree (DD) of chitosan is important to know whether it can be used in a particular application. This driving question requires an experimental procedure that can be carried out by a wide range of instrumental techniques. In this project, techniques such as conductometry, potentiometry, and 1 H NMR were addressed to present an easily reproducible experience for first-year undergraduate students. Students evaluated the applicability of the available instrumental techniques, designed their own laboratory procedures, obtained experimental results, and analyzed data in a challenging experience in which high order thinking and knowledge transfer skills were endorsed. The project described here promotes students' knowledge of instrumental techniques, and offers them an appropriate scenario to develop transferable skills, such as team-working, problem-solving, and written communication, among others.

Synthesis of New Chitosan from an Endemic Chilean Crayfish Exoskeleton (Parastacus Pugnax): Physicochemical and Biological Properties

“…It should be noted that the determination of the first derivative helps in a precise reading of V 1 and V 2 (equivalent points) ( Figure 2 b). According to Pérez-Álvarez et al [ 32 ], in acidic pH’s primary amino groups are protonated, and as NaOH is added during titration, they are neutralized (–NH 3 + + OH − → –NH 2 + H 2 O) and their concentration can, thus, be quantified. In addition, the chitosan pK a value (6.22) was obtained from the potentiometric titration curve.…”

Natural biopolymers as proton conductors in bioelectronics

“…[46,75] The degree of deacetylation of chitosan describes the molar percentage of glucosamine monomeric units and varies from 0 (chitin) to 100 (fully deacetylated chitin or chitosan). [76] Chitosan forms inter and intra-molecular hydrogen bonds in the hydrated state and subsequently ionic complexes with anionic species, F I G U R E 4 A, Chitin deacetylation process to produce chitosan. Reproduced from Ruiz and Corrales, [46] Open access.…”

“…[ 46,75 ] The degree of deacetylation of chitosan describes the molar percentage of glucosamine monomeric units and varies from 0 (chitin) to 100 (fully deacetylated chitin or chitosan). [ 76 ] Chitosan forms inter and intra‐ molecular hydrogen bonds in the hydrated state and subsequently ionic complexes with anionic species, such as lipids, DNA, and some negatively charged synthetic polymers, such as poly (acrylic acid). [ 77 ] Chitosan is a good scaffold for interfacing biological system and electronic devices, especially for immobilization of enzymes in biosensors, [ 78,79 ] tissue engineering, [ 80,81 ] controlled release systems, [ 82,83 ] gene carriers, [ 83 ] and wound healing.…”

Physico-Chemical Studies of Chitosan Derivatives and Optimization of Reaction Conditions using RSM Design

“…From the conductometric titration curves, degree of acetylation and degree of substitution can be calculated (Table-2). The higher degree of acetylation of N,O-carboxymethyl chitosan than chitosan indicates that that (-NH2) groups were also carboxy-methylated (Table-2) [34][35][36].…”