Liquid‐crystalline behavior of chitosan in malic acid

Chang, Jenq Sheng; Chang, Ke; Tsai, Min Lang

doi:10.1002/app.26475

Cited by 17 publications

(14 citation statements)

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“…In this system, for this frame of time, the possibility of malic acid to behave as a cross linker for chitosan, as reported in literature [29] does not seem to be very significant, according to the results obtained, which must be due to the low concentrations of the acids used. for malic acid) and this may be related to the fact that this model assumes that the chitosan chains are in a rigid rod conformation, so this result indicates that the chitosan in the present system is in semi-flexible coil conformation.…”

Section: Citationsupporting

confidence: 75%

Section: Rheological Characterizationsupporting

confidence: 75%

“…Examples include polypeptides [15], proteins [16] poly (nucleic acids) [17][18][19][20] and cellulosics [21,22]. Chitosan belongs to another family of liquid-crystalline biopolymers, which was first reported in 1982 by Ogura et al [23] and since then, quite a number of lyotropic solutions of chitosan derivatives have been found [24][25][26][27][28][29]. Few of these studies concerned the effects of structural factors on the critical concentration (C*) for forming the lyotropic mesophases [30,31,32].…”

Section: Introductionmentioning

confidence: 99%

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2017

MSEIJ

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Chitosan is a biopolymer used in biomedical applications which has the ability to form lyotropic mesophases (chiral nematic) in several solvents. Currently, chitosan liquid crystalline phase is only observed at high polymer concentrations where the system has already transitioned to a gel-like state. Due to the non-homogenous mechanical behavior of a gel, it would be preferable to obtain a liquid crystalline phase while at solution state. Therefore, the formation of chitosan liquid-crystalline at solution state was investigated. Malic and hydrochloric aqueous solutions with different concentrations of chitosan were prepared and the gel formation was followed by rheological measurements. The concentration, C Gel , at which the gel is formed, was found to be dependent on the acid used, the malic aqueous solutions presenting higher C Gel . For the chitosan/malic acid system the chiral nematic mesophase appeared in solution and was preserved in the gel (for C>C Gel ) while for the chitosan/hydrochloric acid system, mesophase was only observed in gel. Using Polarized Optical Microscopy (POM) Swirl-like fingerprint textures typical of cholesteric mesophases were observed and the helical pitch was determined. The existence of mesophases in the gel, in both chitosan aqueous solutions, was also confirmed by rheometry.Keywords: Morphology; Rheology; Cholesteric; Liquid-crystals; Gels IntroductionChitin and chitosan are glycosaminoglycans with the rare property of bioactivity. These polysaccharides are in fact copolymers of β-(1→4)-linked 2-acetamido-2-deoxy-Dglucopyranose and 2-amino-2-deoxy-D-glucopyranose. The difference between the two is determined by the DA, the degree of acetylation, corresponding to the molar fraction of acetyl units constituting the polymer chains. It is considered that chitosan refers to polymers with DAs below 50 % (more commonly 10-30 %) [1]. Chitin is considered the second most abundant polymer in nature but due to its low solubility has limited applications and therefore is mostly used in the deacetylated form, as chitosan. Chitosan is the product of the alkali hydrolysis of chitin and is soluble in dilute acidic solutions [2]. The reason why chitosan presents a higher solubility than chitin is the presence of protonated free amine groups below pH 6.2 [3] and this polycation material has several applications in different fields, from agriculture, waste and water treatment, food and beverages, cosmetic and toiletries, biopharmaceuticals to biomedical applications [4,5]. In biomedical and pharmaceutical applications chitosan is used to produce hydrogels, due to its gelation properties. Several reports on literature can be found concerning the production of chemical [6,7] and physical [8,9] hydrogels from chitosan. Hamdine [10,11] reported an extensive work regarding chitosan gelation in different acids and concluded that chitosan has different behaviours when dissolved in acid malic and in hydrochloric acid. In the first case, due to the considerable volume of the acid molecule, that ...

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Section: Citationsupporting

confidence: 75%

Section: Rheological Characterizationsupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

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2017

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“…It is a high molecular weight polysaccharide containing β-1, 4 glycoside links and is composed of N-acetyl-glucosamine and glucosamine. This cationic biopolymer is remarkably used in pharmaceutical applications due to its unique properties such as non-toxicity, biocompatibility and biodegradability (1,2). Hydrophilic nanoparticles (NPs) of CS have advantages since they can be used for the purposes of controlled drug release, therapeutic effect enhancement and targeted drug delivery (3).…”

Section: Introductionmentioning

confidence: 99%

Preparation and In Vitro Evaluation of Chitosan Nanoparticles Containing Diclofenac Using the Ion-Gelation Method

Kouchak

Azarpanah

2015

Jundishapur J Nat Pharm Prod

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Background: Chitosan-based nanoparticle systems have gained wide interest, mainly for their biocompatibility, biodegradability and mucoadhesive properties. Objectives: The aim of this study was to prepare and evaluate diclofenac-loaded chitosan nanoparticles based on the ionotropic gelation method. Materials and Methods: Chitosan (CS) nanoparticles containing diclofenac was prepared using the ionotropic gelation method. Sodium tripolyphosphate (TPP) was used as a polyanion in this process. The effect of some parameters on particle size and drug loading efficiency was evaluated. Results: Transmission electron microscopy (TEM) photographs exhibited typical spherical shape of particles. The mean particle size was within 129 -166 nm and was affected by homogenization, CS/TPP ratio, CS/drug ratio and pH of medium. The maximum drug loading efficiency was estimated as 65.43 ± 7.03% with CS/drug ratio of 10:1. This value tended to decrease by enhancement of drug proportion in the formulations. Differential scanning calorimetry data confirmed the formation of polyelectrolyte complex of TPP and chitosan. Drug release profile in phosphate buffer solutions (pH 6.8, 7.4) showed initial burst effect followed by a slower release pattern. However, release of diclofenac in the acidic medium was negligible. Conclusions: Diclofenac-loaded nanoparticles based on properties of chitosan gelation could delay the release of drugs in the stomach and be further evaluated for the enteric delivery of diclofenac.

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“…The demineralized powder was soaked in 2M NaOH at 80 C to hydrolyze the protein, and then washed with water till neutral. The alkali-treated powder was soaked in 1% KMnO 4 at room temperature for 1 h to oxidize the astaxanthin. It was then soaked in 1% oxalic acid at 80 C for 1 h in order to neutralize the KMnO 4 ; it was then washed and dried to derive a white chitin powder.…”

Section: Chitosan Preparationmentioning

confidence: 99%

Facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration treatment

Tsai

Tseng

Chang

et al. 2010

J of Applied Polymer Sci

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The objective of this study was to propose a facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration (UF) treatment. The proposed method was based on the degradation rate and rate constant of various process variables, such as: solution temperature, reaction time, concentration of chitosan solution, with or without concurrent removal of degraded fragments during mechanical shearing. The result obtained was that the degradation rate constant was 1.8-6.0 times higher for those using UF to remove smaller degraded molecules concurrently during treatment, than that without UF treatment. The degradation rate constant increased with increasing solution temperature; however, the solution temperature should not exceed than 50 C to prevent the undesired color changes of the resulting product. A method combining mechanical shearing/UF treatment at 50 C and ultrasonic radiation or microfluidization/UF treatment at 30 C is proposed here for a facile method to manipulate the molecular weight of the resultant chitosan with an energy saving, efficient and practical mass production.

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Liquid‐crystalline behavior of chitosan in malic acid

Cited by 17 publications

References 27 publications

Untitled

Untitled

Preparation and In Vitro Evaluation of Chitosan Nanoparticles Containing Diclofenac Using the Ion-Gelation Method

Facile method to manipulate the molecular weight and practical mass production of chitosan by mechanical shearing and concurrent ultrafiltration treatment

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