Chitosan Sub-micron Particles Prepared Using Sulfate Ion Salt as Bacteriostatic Materials in Neutral pH Condition

Kanako Saita,Shoji Nagaoka,Tomohiro Shirosaki,Hirotaka Ihara,Maki Horikawa,Shigeki Matsuda

doi:10.4236/jbnb.2011.24043

Abstract

In this paper, the newly developed ion exchange phase separation method to create chitosan sub-micron particles is introduced: 1) chitosan was dissolved in a lactic acid aqueous solution. 2) the obtained chitosan solution was added stepwise in a sodium sulfate aqueous solution and cooled down to 5℃ to become slightly turbid through agglutination. 3) desalinating and deacidifying of the mixture was carried out by a dialyzing tube method. IR spectroscopy and elemental analysis indicated that the agglutination of chitosan was induced by crosslinking effect with an electrostatic interaction between sulfate anions and amino groups in the glucosamine unit although large excess of Na2SO4 caused undesirable further agglutination of the resultant chitosan particles. As a result, the proper amount of Na2SO4 was approximately 1.0 - 10.0 equivalent for the amino group to create the chitosan particles with a sub-micron size. In addition, we investigated an antibacterial activity test for Escherichia coli of the obtained chitosan particles. The significant antibacterial activity was observed in incubation even at neutral pH condition while the chitosan microbeads (size: ca 200 ∫m) prepared by the conventional method and chitosan granules (size: ca 600 ∫m) as starting materials showed almost no antibacterial activity in the same condition.

Highlights

Chitosan is a cationic biopolymer obtained from Ndeacetylation of chitin, β-(1,4)-N-acetyl-D-glycan [1]
The newly developed ion exchange phase separation method to create chitosan sub-micron particles is introduced: 1) chitosan was dissolved in a lactic acid aqueous solution; 2) the obtained chitosan solution was added stepwise in a sodium sulfate aqueous solution and cooled down to 5 ̊C to become slightly turbid through agglutination; 3) desalinating and deacidifying of the mixture was carried out by a dialyzing tube method
We introduce a new method as the “ion exchange phase separation method” to create submicron particles from chitosan without using any organic emulsifier and solvent as well as with no heating process

Summary

Introduction

Chitosan is a cationic biopolymer obtained from Ndeacetylation of chitin, β-(1,4)-N-acetyl-D-glycan [1]. Chitosan and derivatives have become useful polysaccharides in the biomedical field. It was popular to use chitosan as antibacterial compounds in agriculture, as elicitors of plant defense responses [13], as additives in the food industry, as flocculating agents for wastewater [14] and as pharmaceutical agents in biomedicine [15,16]. In this content, environmentally antibacterial activity of chitosan has received considerable attention recently. These activities are limited to acidic conditions because of its poor solubility above pH 6.5, where chitosan starts to lose its cationic nature [17,18,19,20]

Methods

Results

Conclusion