Self-assembled Chitosan Research Articles

Formation of Biocompatible Nanoparticles by Self-Assembly of Enzymatic Hydrolysates of Chitosan and Carboxymethyl Cellulose

A simple preparation method for biocompatible nanoparticles in high concentration (0.5 wt %) by self-assembly of chitosan and carboxymethyl cellulose hydrolysates was developed. Chitosan and carboxymethyl cellulose were hydrolyzed beforehand with chitosanase and cellulase respectively to make fragments having lower molecular weights. Nanoparticles were spontaneously formed only by mixing the two hydrolysate solutions. The particle size distribution was relatively narrow, about 200 nm in mean size. The mean particle size decreased from 226 nm to 165 nm with decreasing molecular weight of chitosan hydrolysate from 9.5 to 6.8 kDa. The mixing ratio of chitosan and carboxymethyl cellulose hydrolysates also affected particle size. Changes in particle size are discussed in relation to a possible mechanism of polyionic complexation. The chitosan-carboxymethyl cellulose nanoparticles were stably suspended over 1 week even under low pH (pH 3.0), high ionic strength (NaCl 1 M), or low temperature (4 degrees C) conditions.

Polyion Complex Fiber and Capsule Formed by Self-Assembly of Chitosan and Poly(α,L-glutamic acid) at Solution Interfaces

Different characteristic surface structures such as spherical capsules, regularly spaced droplets and fibers are formed by electrostatic polysaccharide interaction between chitosan and poly(α,L-glutamic acid) via polyion complex (PIC) formation. Spherical droplet-like PIC capsules of varying diameters form in solutions. Some dyes adsorb on the surface of the capsules, while other dyes and benzoic acid derivatives penetrate into the capsules. The PIC fiber can be prepared by reactive-spinning at the solution interface, followed by gravity and by removing water in ethanol. The tensile strength of the fiber is 11.2 kg·mm–2 (1.48 g·denier–1) and the knotting strength is 2.15 kg·mm–2 (0.30 g·d–1). By reaction with an organic cross-linking agent, ethylene glycol diglycidyl ether (EGDE), the tensile strength of the fiber can be increased to 18.1 kg·mm–2 (3.14 g·d–1), and by reacting with hexamethylene diisocyanate (HMDI), the knotting strength of the fiber can be increased to 7.58 kg·mm–2 (0.89 g·d–1). The interaction energies (work of adsorption, Wads) of PLG and chitosan in aqueous solution were estimated by a surface chemical approach, and a relationship between the Wads values and the tensile strengths of the PIC fibers and the Wads indicated that the higher Wads system gives the higher tensile strength. The PIC fiber can be dyed by four different dyeing procedures such as direct and vat dyeings. When the cross-linked PIC fiber was incubated in an aqueous solution in the presence of endocrine disruptor related compounds such as dibenzofuran and biphenyl, these compounds were accumulated onto and/or into the fibers.

Polyion Complex Fiber and Capsule Formed by Self-Assembly of Chitosan and Poly(α,L-glutamic acid) at Solution Interfaces

Different characteristic surface structures such as spherical capsules, regularly spaced droplets and fibers are formed by electrostatic polysaccharide interaction between chitosan and poly(α,L-glutamic acid) via polyion complex (PIC) formation. Spherical droplet-like PIC capsules of varying diameters form in solutions. Some dyes absorb on the surface of the capsules, while other dyes and benzoic acid derivatives penetrate into the capsules. The PIC fiber can be prepared by reactive-spinning at the solution interface, followed by gravity and by removing water in ethanol. The tensile strength of the fiber is 11.2 kg . mm -2 (1.48 g . denier -1 ) and the knotting stength is 2.15 kg . mm -2 (0.30 g . d -1 ). By reaction with an organic cross-linking agent, ethylene glycol diglydyl ether (EGDE), the tensile strength of the fiber can be increased to 18.1 kg . mm -2 (3.14 g . d -1 ), and by reacting with hexamethylene diisocyanate (HMDI), the knotting strength of the fiber can be increased to 7.58 kg . mm-2 (0.89 g . d -1 ). The interaction energies (work of absorption, W ads ) of PLG and chitosan in aqueous solution xere estimated by a surface chemical aaprroach, and a relationship between the W ads values and the tensile strength of the PIC fibers and the Wads indicated that the higher W ads system gives the higher tensile strength. The PIC fiber can be dyed by four different dyeing procedure such as direct and vat dyeings. When the cross-linked PIC fibers was incubated in an aqueous solution in the presence of endocrine disruptor related compounds such as dibenzofuran and biphenyls, these compounds were accumalated onto and/or into the fibers.

Polyion complex fiber and capsule formed by self-assembly of chitosan and gellan at solution interfaces

Different characteristic surface structures such as spheres and hemispheres, honeycomb, regularly spaced droplets and fibers are formed by electrostatic polysaccharide interaction between chitosan and gellan gum via polyion complex (PIC) formation. Spherical droplet-like PIC capsules of varying diameter form in solution. Some dyes adsorb on the surface of the capsules, while other dyes and benzoic acid penetrate into the capsules. The PIC fiber is spinnable by gravity and wet spinning in ethanol. This fiber possesses a counterion pairing structures and exhibits a nervation/veining pattern or a hollow yarn pattern. The tensile strength of the fiber is 18.4 kg/mm 2 (2.42 g/denier) and the knotting strength is 3.0 kg/mm 2 (0.40 g/d). By reaction with an organic cross-linking agent, e.g., hexamethylene diisocyanate, the tensile and knotting strengths of the fiber increased to 36.0 kg/mm 2 (3.99 g/d) and 9.2 kg/mm 2 (1.07 g/d), respectively. The PIC fiber can be dyed by different dyeing procedures such as direct and vat dyeing.