Impact of Crystalline Structural Differences Between α- and β-Chitosan on Their Nanoparticle Formation Via Ionic Gelation and Superoxide Radical Scavenging Activities.

Yattra Jampafuang,Anan Tongta,Yaowapha Waiprib

doi:10.3390/polym11122010

Abstract

α- and β-Chitosan nanoparticles were obtained from shrimp shell and squid pen chitosan with different set of deacetylation degree (%DD) and molecular weight (MW) combinations. After nanoparticle formation via ionic gelation with sodium tripolyphosphate (TPP), the % crystallinity index (%CI) of the α- and β-chitosan nanoparticles were reduced to approximately 33% and 43% of the initial %CI of the corresponding α- and β-chitosan raw samples, respectively. Both forms of chitosan and chitosan nanoparticles scavenged superoxide radicals in a dose-dependent manner. The %CI of α- and β-chitosan and chitosan nanoparticles was significantly negatively correlated with superoxide radical scavenging abilities over the range of concentration (0.5, 1, 2 and 3 mg/mL) studied. High %DD, and low MW β-chitosan exhibited the highest superoxide radical scavenging activity (p < 0.05). α- and β-Chitosan nanoparticles prepared from high %DD and low MW chitosan demonstrated the highest abilities to scavenge superoxide radicals at 2.0–3.0 mg/mL (p < 0.05), whereas α-chitosan nanoparticles, with the lowest %CI, and smallest particle size (p < 0.05), prepared from medium %DD, and medium MW chitosan showed the highest abilities to scavenge superoxide radicals at 0.5–1.0 mg/mL (p < 0.05). It could be concluded that α- and β-chitosan nanoparticles had superior superoxide radical scavenging abilities than raw chitosan samples.

Highlights

Chitosan is a derivative of chitin, which is the second most abundant polymer in Nature after cellulose [1,2,3,4]
Three polymorphic forms (α, β and γ) of chitin have been discovered, which differ in the arrangement of the chains in the crystalline regions; that is, α-chitin has antiparallel chains, while β-chitin has parallel chains for, and γ-chitin is a combination of α- and β-chitin [1,2]. α-Chitosan has been commercially manufactured from shrimp and crab shells and has been widely applied in various fields, whereas β-chitosan has been commonly obtained from squid pens and has a limited number of studies and applications, primarily due to its limited availability [5,6,7,8]
The highlight of this work was the preparation of α- and β-chitosan nanoparticles from shrimp shell and squid pen chitosan products with different sets of molecular weight (MW) and deacetylation degree (%DD) combinations in order to relate their different crystalline structures to their antioxidant properties on superoxide radicals

Summary

Introduction

Chitosan is a derivative of chitin, which is the second most abundant polymer in Nature after cellulose [1,2,3,4]. It was reported that the β-chitin crystalline structure was more modified than that of α-chitin after deacetylation, resulting in better properties such as degree of solubility, and swelling capacitity [1,7], which . Polymers 2019, 11, 2010 affect their antioxidant activity [7,8]. The antioxidant activities of chitosan have been extensively studied both in vitro and in vivo using different methodologies and are reported to be correlated to its structural characteristics such as degree of deacetylation (%DD), molecular weight (MW), as well as the source of the material [9,10,11]. The physicochemical properties of chitosan end products can be modulated by controlling factors such as chitin source of origin, reaction conditions (concentration, ratios of chitin to alkali, temperature), and extent of the reaction. It is known that hydroxyl, and amino groups in chitosan are key components in eliminating anion radicals such as superoxide and hydroxyl radicals [8,9,10,12]

Objectives

Methods

Results

Conclusion