Chitosan In Acetic Acid Research Articles

Fabrication of ultrathin films based on chitosan and bovine serum albumin and their stability studied with the radio-labeled method

Chitosan (CS)/bovine serum albumin (BSA) ultrathin films were fabricated on the modified quartz wafer through the layer-by-layer deposition technique. The effects of the experimental conditions, such as pH, molecular weight (MW), ionic strength and the coexistence of the additional polyanions on the fabrication and the stability of assembly films were investigated with a radio-labeled method. The results show that the amount of adsorbed BSA is proportional to the number of assembly cycle except the first two cycles and CS/BSA films fabricated in CS acetic acid aqueous solution (aq. AcOH) at pH 5.2 are more favorable compared with at pH 1.0. When two different MW CS were used ( M η≈1.2×10 5, M η≈1.0×10 6), the lower MW CS adsorbs more BSA, but the films formed are less stable. The same trend is observed, i.e. the amount of adsorbed BSA in deionized water is higher but the films fabricated are less stable than in phosphate-buffered saline (PBS). The adsorption of BSA in the presence of poly(sodium styrene-sulfonate) (PSS) decreases severely due to existence of the strong interaction between BSA and PSS, which has been confirmed by the fluorescence spectrometry. The morphology of CS/BSA assembly films was visualized with atomic force microscopy (AFM) and shows that some aggregates of BSA occur and are eluted first in 1% sodium dodecyl sulfate (SDS) aqueous solution.

Preparation and characterization of chitosan/carboxymethylated konjac glucomannan blend films

In order to improve the mechanical and water swelling properties of the chitosan (CS) film, a series of transparent films were prepared by blending 2% (weight) chitosan acetic acid solution with 1.5% (weight) carboxymethylated konjac glucomannan (CMKGM) aqueous solution according to predetermined ratio and drying at 30°C. The morphological structure, miscibility, thermal stability, mechanical properies, and swelling capacity of the blend films were studied by infrared (IR), X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron micrograph (SEM), and measurements of the mechanical properties and swelling properties. The results demonstrated that there was strong interaction and good miscibility between CS and CMKGM resulted from intermolecular hydrogen bonding and electrostatic force. The mechanical properties in dry state and wet state, thermostability, and water swelling properties of the blend films were obviously improved. The best values of the tensile strength in the dry and wet state achieved 89 MPa and 49 MPa, respectively, when the CMKGM content was 30% (weight). The CS/ CMKGM blend films provided promising biomedical applications.

Oxygen and Water Barrier Properties of Coated Whey Protein and Chitosan Films

Films of whey protein and chitosan acetic acid salt have lower oxygen permeability than, for example, ethylene-co-vinylalcohol under dry conditions, but water and water vapor seriously impair the gas barrier properties. To reduce the oxygen permeability at 90% relative humidity and the water-vapor transmission rate at 100% relative humidity, the films were coated with an alkyd, a beeswax compound, or a nitrocellulose lacquer. Permeability and transmission rate measurements were performed in accordance with standard methods and showed that the beeswax compound and the nitrocellulose were appropriate as water-vapor barriers. Overall migration to water was measured after 10 days exposure time, with the coated surface exposed to the water, showing that the alkyd-coated and the nitrocellulose-coated films were both below the safety limit for food contact. Water absorbency tests, performed by the Cobb method, showed that the films coated with the beeswax compound or with nitrocellulose lacquer exhibit lower absorbency than the alkyd-coated films.

Properties of nitrocellulose‐coated and polyethylene‐laminated chitosan and whey films

Chitosan (chitosan acetic acid salt) and whey (65% protein) films were coated with a nitrocellulose lacquer or laminated with polyethylene to enhance their water resistance and gas barrier properties in humid environments. The barrier properties were measured by the Cobb60 test and water-vapor (100% relative humidity) transmission and oxygen (90% relative humidity) permeability tests. Mechanical properties were obtained with tensile tests. Packaging properties were studied with crease and folding tests. The Cobb60 test revealed that the coated films were resistant to liquid water, at least for a short exposure time, if the coating thickness was at least 10–17 μm. Water-vapor transmission rates comparable to those of polyethylene-laminated films were obtained for coated chitosan at a coating thickness of 5–7 μm. The coated films possessed low oxygen permeability despite the high humidity. Coated films dried for 3 weeks showed oxygen permeabilities at 90% relative humidity that were similar to values for dry ethylene-co-vinyl alcohol at 0% relative humidity. The lacquer partly penetrated the whey films, and this led to excellent adhesion but poor lacquer toughness. The lacquer coating on chitosan was tougher, and it was possible to fold these films 90° without the coating fracturing if the coating thickness was small. The coated whey films were readily creasable. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 985–992, 2001

Properties of nitrocellulose‐coated and polyethylene‐laminated chitosan and whey films

AbstractChitosan (chitosan acetic acid salt) and whey (65% protein) films were coated with a nitrocellulose lacquer or laminated with polyethylene to enhance their water resistance and gas barrier properties in humid environments. The barrier properties were measured by the Cobb60test and water‐vapor (100% relative humidity) transmission and oxygen (90% relative humidity) permeability tests. Mechanical properties were obtained with tensile tests. Packaging properties were studied with crease and folding tests. The Cobb60test revealed that the coated films were resistant to liquid water, at least for a short exposure time, if the coating thickness was at least 10–17 μm. Water‐vapor transmission rates comparable to those of polyethylene‐laminated films were obtained for coated chitosan at a coating thickness of 5–7 μm. The coated films possessed low oxygen permeability despite the high humidity. Coated films dried for 3 weeks showed oxygen permeabilities at 90% relative humidity that were similar to values for dry ethylene‐co‐vinyl alcohol at 0% relative humidity. The lacquer partly penetrated the whey films, and this led to excellent adhesion but poor lacquer toughness. The lacquer coating on chitosan was tougher, and it was possible to fold these films 90° without the coating fracturing if the coating thickness was small. The coated whey films were readily creasable. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 985–992, 2001

Erratum: Coagulation rate studies of spinnable chitosan solutions

The authors regret that some errors were made in the theoretical text of this article. They apologize for the inconvenience and offer the following corrected paragraphs, which replace the corresponding, erroneous paragraphs appearing in the second column of page 121 of the original article. That the solidification of chitosan in acetic acid involves an acid/base reaction and the resulting production of water. This mechanism has been outlined above in the Introduction section. The production of water was further evidenced by the swelling of the polymer samples during the coagulation step, and the subsequent reduction in volume if the samples were allowed to air dry. That there is no diffusion of the acid, or proton, from the liquid core through the solidified polymer. The OH− ions migrate (i.e., from outside the sample) through the solidified layer to the boundary where solid polymer meets liquid polymer. There, the anions react with the proton to precipitate solid polymer. So then, while the OH− ions diffuse through the solid polymer to the boundary, the H+ ions likely do not diffuse out of the liquid center at all. Instead, they only make it as far as the boundary, where they instantaneously react with the anions. This supposition is based on the fact that the concentration of the coagulant (1M KOH) is greater than that of the solvent (0.33M CH3COOH).

Optical waveguiding and morphology of chitosan thin films

An investigation was made of the optical and waveguiding properties of thin films fabricated from solutions of chitosan-acetic acid (chitosan/HAc) and chitosan/HAc doped with rare-earth metal ions (Er+++ or Nd+++). For all three films, the refractive indices were approximately 1.5 and there was nearly no absorption in the range of 300 to 2700 nm. The optical loss in a waveguides was less than 0.5 dB/cm. Morphological observations disclosed that all the films possessed a dense and homogeneous amorphous structure with smooth surfaces. Extrinsic scattering, especially the scattering caused by surface impurities, was the dominating factor affecting the optical loss value. It is also interesting to note that for all the films, doped with rare-earth metal ions or not, the morphological characteristics were alike and the optical properties were similar. Doping rare-earth metal ions into chitosan thin films did not seriously influence optical waveguiding. This paper reports, we believe, the first study of chitosan films for optical applications. The experimental results demonstrate that chitosan and its derivatives are potential candidates for optical materials. © 1996 John Wiley & Sons, Inc.

Preparation and evaluation of cross-linked chitosan microspheres containing furosemide

Chitosan microspheres containing furosemide were prepared from a w/o emulsion system using liquid paraffin as the external phase and a solution of chitosan in acetic acid as the disperse phase. Discrete spherical furosemide microspheres having a 350–690 μm diameter range were produced. Microsphere properties were affected by the preparation variables such as the type and concentration of chitosan, drug concentration, cross-linking process, the viscosity of oil and stirring rate during the preparation. The results were examined kinetically. Dissolution data indicated that the release followed the Higuchi matrix model.

PH‐sensitivity of hydrogels based on complex forming chitosan: Polyether interpenetrating polymer network

AbstractThis article deals with a novel, semi‐interpenetrating polymer network (semi‐IPN), composed of crosslinked chitosan (cr‐CS) with glutaraldehyde (GA) and polyether. The pH responsibility of swelling data shows that swelling reaches a maximum at pH = 3.19 and a minimum at pH = 13. The concentration of chitosan acetic acid solution, the amount of crosslinking agent, and polyether, have effects on the swelling behavior of the network. Stimulating‐response of the semi‐IPN, induced by abrupt changes of pH between 1 and 13, is discussed as well. © 1993 John Wiley & Sons, Inc.

Pervaporation separation of water‐ethanol through modified chitosan membranes, II. Carboxymethyl, carboxyethyl, cyanoethyl, and amidoxime chitosan membranes

The present study investigates the pervaporation performance of four kinds of modified chitosan membranes to separate water from aqueous ethanol solution. Chitosan was prepared from chitin abstracted from the crab shell and subsequently deacetylated with aqueous NaOH solution. Modified chitosan membranes examined in this study include carboxymethyl chitosan, carboxyethyl chitosan, cyanoethyl chitosan, and amidoxime chitosan. The incorporation of hydrophilic functional groups into the 6-O position of chitosan enhances the selectivity of modified chitosan membrane compared to the previously reported chitosan-acetic acid complex membrane. Among the modified chitosan membranes, membranes containing carboxy groups show the best pervaporation performance. Carboxymethyl chitosan membranes show the maximum swelling and ethanol flux at approx. 15 wt.-% feed ethanol concentration due to the coupling and plasticizing effect.

Selective permeabilities of chitosan-acetic acid complex membrane and chitosan-polymer complex membranes for oxygen and carbon dioxide

Chitosan-acetic acid complex membrane and several chitosan-polymer complex membranes have been prepared and the gas permeabilities of these membranes have been examined. It has been found that chitosan-acetic acid complex membrane shows high permselectivities for oxygen and carbon dioxide, and synthetic polymers can modify the permeation behavior of chitosan membrane for oxygen and carbon dioxide. The separation factor αCO2/O2 of these membranes were much smaller than unity, indicating possible applications for the preservations of fruits and vegetables. It has been noticed that the permeation behaviors of these membranes are markedly influenced by metal ions added into the membranes and the membranes have good mechanical strength.