Relation between the Degree of Acetylation and the Electrostatic Properties of Chitin and Chitosan

Abstract

A series of chitosan/chitin samples with DA's varying between 5.2 and 89% was prepared from the reacetylation under soft conditions of a unique chitosan sample allowing the preservation of the chain distribution. The study of the variation of pH for the same concentration of amine groups, at different ionic strengths, on the scale of DA's allows us to extrapolate the variation of pKa at dissociation degrees (alpha) 0 and 1. A modeling of all the curves was obtained by means of only one equation. Then, for given concentration of chitosan and ionic strength, it is possible to predict the pH of the solution whatever the DA and alpha. The role of DA through the participation of hydrophobic interactions and hydrogen bondings on the electrostatic parameters is discussed. The results allow a better understanding of some physicochemical and biological properties of chitosan and chitin.

Protein delivery based on uncoated and chitosan-coated mesoporous silicon microparticles

“…At a subsequent stage, MS-MPs were modified through the deposition of a chitosan (CS) coating, thus forming a multifunctional silicon/polymer composite with potential for advanced biomedical applications, a concept that has been recently explored in some recent works [23,24]. The rational behind the selection of CS as the coating polymer was: (i) its know capacity to adsorb to polyactionic surfaces, (ii) its established pharmaceutical record, (iii) and its mucoadhesivess and permeation enhancing properties [25][26][27][28]. The global concept was to generate a drug delivery system that would combine silicon drug loading properties with the unique characteristics of CS-coated systems for transmucoal drug delivery.…”

Enhanced cellular uptake and long-term retention of chitosan-modified iron-oxide nanoparticles for MRI-based cell tracking

“…Our approach in particular is to surface functionalize ultrasmall (∼5 nm) SPIO NPs with water soluble chitosan -deacetylated chitin from crustacean shells. Chitosan is a linear polysaccharide of β-(1-4)-linked D-glucosamine (deacetylated) and N-acetyl-D-glucosamine that is polycationic 27,28 and spontaneously deposits on the negatively charged carboxylated surface of a USPIO NP. This physical association is then strengthened by chemical crosslinking using carbodiimide chemistry to link primary amines on the chitosan backbone to carboxyl groups on the nanoparticle surface via an amide linkage.…”

Potential Applications of Chitosan Nanoparticles as Novel Support in Enzyme Immobilization

“…Chitosan due to its unique physico-chemical and biological properties is an attractive material for use in various applications (Sorlier et al, 2001;Yang et al, 2010). These properties include: biodegradability, lack of toxicity, antibacterial and antifungal effects, wound healing acceleration and immune system stimulation (Shi et al, 2011a).…”

“…Its pK a is about 6.3 (Sorlier et al, 2001). At lower pH solutions (<pK a ), most of the amino groups are protonated, making chitosan a water soluble polyelectrolyte.…”