Evaluation of an improved acid hydrolysis-HPLC assay for the acetyl content in chitin and chitosan

A novel method to quantify chitosan in aqueous solutions by ultrahigh-performance liquid chromatography-tandem mass spectrometry

In this study, a novel and accurate quantitative analysis method for the direct determination of chitosan (CS) in aqueous solutions using ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) is presented. By detecting the mass spectrum response intensity of a series of CS characteristic ion pairs, the sample concentration (abscissa) was linearly fitted with the total ion current (TIC) response intensity of its characteristic ion pairs (ordinate). A reliable standard curve was derived for quantifying CS in the range of 125-4000 ng/mL. Under the detection conditions, this CS quantification method yielded acceptable specificity (no interference peak), linearity (with correlation coefficient (r2) values >0.999), precision (acceptable limit RSDr < 3 %, RSDR < 6 %), accuracy (RE within the acceptable limits of ±5 %), and stability (acceptable limit RE within ±5 %, RSDr < 3 %). Moreover, the applicability of measurement was verified when a series of substrates did not interact with CS in the solution. Results have verified the applicability of this method for determining CS content in different composites. This study provides a method for determining CS content with significant practical value and economic benefit.

Determination of chitosan content with Schiff base method and HPLC

Tremendous awareness of determination of chitosan content accurately is increasing, due to it has great significance to the quality control of chitosan. In this article, two kinds of chitosan-Schiff base derivatives (BCSB and PCSB) were synthesized by the different average degrees of deacetylation (DD) of chitosan with benzaldehyde or propanal, respectively. The total mass of Schiff base derivative product was dried and obtained without washing and loss. Then, a certain amount of the prepared Schiff base compound was taken to hydrolyze into glucosamine hydrochloride (GAH) in strong hydrochloric acidic environment, whose concentration was quantified by HPLC, and the mass of GAH contained in hydrolysis solution could be calculated. Subsequently, the total quality of GAH obtained by hydrolysis of all of the Schiff base product was calculated and obtained, and then the theoretical mass of chitosan could be deduced and calculated by further converse calculation. Finally, the chitosan content was obtained by combining the sample mass used in Schiff base reaction and the theoretical mass of chitosan. This method was accurate and convenient, providing a preeminent idea and method for the determination of chitosan content.

A New Rapid and Sensitive Spectrophotometric Method for Determination of a Biopolymer Chitosan

A novel approach of spectrophotometric quantification of chitosan based on one-step depolymerization with sodium nitrite followed by reaction of the end product with thiobarbituric acid has been proposed, optimized, and validated. In this process, chitosan is converted into 2,5-anhydro-D-mannose that reacts with thiobarbituric acid to form pink color. The color that resulted from the reaction was stabilized and measured at 555 nm. The method optimization was essential as many procedural parameters influenced the accuracy of the determination including hydrolysis conditions, thiobarbituric acid concentration, reaction time, pH, reaction temperature, and color stability period. Under given optimized conditions that appeared to be critical, chitosan was quantitatively analyzed and the calibration graph was linear over the range of 10–50 μg/mL (). This approach was applied for determination of chitosan in pharmaceutical formulation (chitocal) and had a recovery rate of higher than 96%. The developed method is easy to use and highly accurate.

Chitin

A comprehensive profile of chitin with 61 references is reported. A full description including nomenclature, formulae, elemental analysis, and appearance is included. Methods of preparation for chitin and its derivative, such as chitosan, are discussed. Physical properties, analytical methods, uses and applications, stability, biodegradability, and toxicity of chitin are also reviewed.

New generation of chitosan-encapsulated ZnO quantum dots loaded with drug: synthesis, characterization and in vitro drug delivery response

The objective of the study is to describe a new approach of combining quantum dots technology with anti-cancer drug therapy. In this regard, we communicate the preliminary research on the synthesis of blue-light emitting ZnO quantum dots (QDs) combined with biodegradable chitosan (N-acetylglucosamine) for tumor-targeted drug delivery. The results presented here indicate that the proposed new generation of QDs loaded with anti-cancer agents and encapsulated with biocompatible polymer represent a potential platform to deliver tumor-targeted drugs and document the delivery process, if desired. Non-toxic water-dispersed ZnO QDs with long-term fluorescence stability were synthesized by a chemical hydrolysis method, encapsulated with chitosan and loaded with anti-cancer drug. Chitosan enhanced the stability of the QDs because of the hydrophilicity and cationic charge of chitosan. The study points toward the application of water-dispersed ZnO QDs with long-term fluorescence stability for design of new drug release carrier.

Determination of glucosamine and N-acetyl glucosamine in fungal cell walls

A new method was developed to determine glucosamine (GlcN) and N-acetyl glucosamine (GlcNAc) in materials containing chitin and chitosan, such as fungal cell walls. It is based on two steps of hydrolysis with (i) concentrated sulfuric acid at low temperature and (ii) dilute sulfuric acid at high temperature, followed by one-step degradation with nitrous acid. In this process, chitin and chitosan are converted into anhydromannose and acetic acid. Anhydromannose represents the sum of GlcN and GlcNAc, whereas acetic acid is a marker for GlcNAc only. The method showed recovery of 90.1% of chitin and 85.7-92.4% of chitosan from commercial preparations. Furthermore, alkali insoluble material (AIM) from biomass of three strains of zygomycetes, Rhizopus oryzae, Mucor indicus, and Rhizomucor pusillus, was analyzed by this method. The glucosamine contents of AIM from R. oryzae and M. indicus were almost constant (41.7 +/- 2.2% and 42.0 +/- 1.7%, respectively), while in R. pusillus, it decreased from 40.0 to 30.0% during cultivation from 1 to 6 days. The GlcNAc content of AIM from R. oryzae and R. pusillus increased from 24.9 to 31.0% and from 36.3 to 50.8%, respectively, in 6 days, while it remained almost constant during the cultivation of M. indicus (23.5 +/- 0.8%).

A stimulus-responsive magnetic nanoparticle drug carrier: magnetite encapsulated by chitosan-grafted-copolymer

We describe a magnetic nanoparticle drug carrier for controlled drug release that responds to the change in external temperature or pH, with characteristics of longer circulation time and reduced side effects. The novel nanocarrier is characterized by a functionalized magnetite (Fe(3)O(4)) core that is conjugated with drug via acid-labile hydrazone-bond and encapsulated by the thermosensitive smart polymer, chitosan-g-poly(N-isopropylacrylamide-co-N,N-dimethylacrylamide) [chitosan-g-poly(NIPAAm-co-DMAAm)]. The chitosan-g-poly(NIPAAm-co-DMAAm) smart polymer exhibits a lower critical solution temperature (LCST) of approximately 38 degrees C, signifying phase transition behavior of the smart polymer and enabling its use for triggering on-off mechanisms. The drug release response was appreciably low at a temperature less than the LCST as compared with a temperature above the LCST. In each case, there was an initial rapid drug release, followed by a controlled released in the second stage, especially in a mild acidic buffer solution of pH 5.3. We believe that the drug release occurs via a collapse of the encapsulated thermosensitive polymer and cleavage of the acid-labile hydrazone linkage.

Extraction and precipitation of chitosan from cell wall of zygomycetes fungi by dilute sulfuric acid

A new method was developed in this work for extraction of chitosan from the zygomycetes cell wall. It is based on the temperature-dependent solubility of chitosan in dilute sulfuric acid. Chitin is soluble in neither cold nor hot dilute sulfuric acid. Similarly chitosan is not soluble at room temperature but is dissolved in 1% H 2SO 4 at 121 degrees C within 20 min. The new method was developed to measure the chitosan content of the biomass and cell wall. The procedures were investigated by measuring phosphate, protein, ash, glucuronic acid, and degree of acetylation. The cell wall derivatives of fungus Rhizomucor pusillus were then examined by this new method. The results indicated 8% of the biomass as chitosan. After treatment with NaOH, the alkali-insoluble material (AIM) contained 45.3% chitosan. Treatment of AIM with acetic acid resulted in 16.5% acetic-acid-soluble material (AcSM) and 79.0% alkali- and acid-insoluble material (AAIM). AcSM is usually cited as pure chitosan, but the new method shows major impurities by, for example, phosphate. Furthermore, AAIM is usually considered to be the chitosan-free fraction, whereas the new method shows more than 76% of the chitosan present in AIM is found in AAIM. It might indicate the inability of acetic acid to separate chitosan from the cell wall.

Peripheral enzymatic deacetylation of chitin and reprecipitated chitin particles

The enzymatic deacetylation of various chitin preparations was investigated using the fungal chitin deacetylase (CDA) isolated from Rhizopus oryzae growth medium. Specific extracellular enzyme activity after solid state fermentation was 10 times higher than that after submerged fermentation. Natural crystalline chitin is a very poor substrate for the enzyme, but showed a five-time better deacetylation after dissolution and reprecipitation. Chitin particles, enzymatically deacetylated for only 1% exhibited a strongly increased binding capacity towards ovalbumin, while maintaining the rigidity and insolubility of chitin in a moderate acidic environment. Because of the unique combination of properties, these CDA treated chitin materials were named "chit-in-osan". Chitinosan was shown to be an attractive matrix for column chromatography because no hydrogel formation was observed, that impaired the flow of eluent. Under the same conditions, partially deacetylated chitosan swelled and blocked the flow in the column.