Deacetylation of Chitosan: Material Characterization and in vitro Evaluation via Albumin Adsorption and Pre-Osteoblastic Cell Cultures

Abstract

Degree of deacetylation (DDA) and molecular weight (MW) of chitosans are important to their physical and biological properties. In this study, two chitosans, HS (DDA = 73.3%) and AT (DDA = 76.8%), were deacetylated with 45% sodium hydroxide under nitrogen atmosphere at 80 °C or 90 °C for up to 120 min, to obtain two series of chitosans. The polymers produced were characterized for MW by gel permeation chromatography, DDA by titration and UV-vis methods, and crystallinity, hydrophilicity and thermal stability by X-ray diffraction, water contact angle and differential scanning calorimetry respectively. Films, made by solution casting in dilute acetic acid at ambient conditions, were evaluated for biological activity by albumin adsorption and the attachment and growth of a pre-osteoblast cell line. Chitosans with between 80–93% DDA’s (based on titration) were reproducibly obtained. Even though deacetylation under nitrogen was supposed to limit chain degradation during decetylation, MW decreased (by maximum of 37.4% of HS and 63.0% for AT) with increasing deacetylation reaction time and temperature. Crystallinity and decomposition temperature increased and water contact angles decreased with processing to increase DDA. Significantly less albumin was absorbed on films made with 93% DDA chitosans as compared with the original materials and the AT chitosans absorbed less than the HS chitosans. The cells on higher DDA chitosan films grew faster than those on lower DDA films. In conclusion, processing conditions increased DDA and influenced physicochemical and biological properties. However, additional studies are needed to unambiguously determine the influence of DDA or MW on in vitro and in vivo performance of chitosan materials for bone/implant applications.

Rheology and Thermal Studies of Stearoyl Chitosan Varying the Degree of Substitution

“…Deacetylated chitosan was synthesized by 'sodium hydroxide deacetylation of chitosan [12][13][14]. Chitosan, which has a DD of 75-85% (5 g), was reacted with 50% sodium hydroxide solution (50 mL) at a 1:10 (W/V) ratio in a round bottom flask (250 mL) under nitrogen atmosphere for four hours at 100 °C.…”

Cytotoxicity of Different Degrees of De-Acetylated Chitosan on 3T3- and Two Human Tooth Fibroblast Cell-Lines

“…15 Different degrees of de-acetylation (DDA) of chitosan is normally obtained by the treatment of chitin with alkali and a higher DDA is obtained by increasing the time and temperature, while the molecular weight (mw) of chitosan is dependent on the initial source of material which could be crap, fungi, shrimp etc. This mw normally decreases in the process to obtain a higher DDA [12]. In this study an 87% product with a mw of 2500 kDa was used as received, while the 70% (mw 145kDA] and 40% (mw 15kDA) were prepared.…”

“…It was reported that the degree of de-acetylation (DDA) and the molecular weight are important parameters which determines many physiochemical and biological properties of chitosans [12].…”

“…For the other de-acetylated products: Chitin was de-acetylated to ~70% (mw 45 kDa) and ~40% (mw 15 kDa) by the use of 45% sodium hydroxide solution in a 1:10 (W/V) ratio in a reaction vessel following Zhang's method [11] and the reaction was under nitrogen atmosphere [12]. A Balb/c 3T3 mouse fibroblast cell line (The National Repository for Biological Materials, Sandringam) was maintained and cultured under standard conditions [13].…”

Removal of Fe (Ii) and Mn (Ii) From Wastewater Using Nano-Chitosan Prepared From Shrimp Waste

“…Then the solution was boiled for 2 h after that alkali solution was drained off and washed repeatedly with DI till pH was lowered to normal. Finally, chitosan was further dried at room temperature and stored for further uses [19].…”