Microcrystalline Chitosan Research Articles

Study on the rheological properties of microcrystalline chitosan hydrogels used as drug carriers

Study on the rheological properties of microcrystalline chitosan hydrogels used as drug carriers

Functional hybrid fibers of cellulose/microcrystalline chitosan. I. Manufacture of viscose/microcrystalline chitosan fibers

Blends of microcrystalline chitosan (MCCh) with cellulose xhanthate alkaline solutions were prepared to investigate the effects of aqueous MCCh gel concentration and additives on the spinnability of hybrid cellulose/chitosan fibers and their properties. The properties of the spinning solution were mainly dependent on the concentration of MCCh in the aqueous gel-like dispersion and the amount mixed into the cellulose xhanthate solution. Sodium alginate chemically close to cellulose and chitosan was used as an additive to improve the miscibility of chitosan due to the ionic bonds formed with chitosan 2-amino groups. Using an optimized ratio of 2 : 1 of MCCh to the sodium alginate, a maximum of 6% of MCCh calculated from alpha-cellulose content could be introduced into the sodium xhanthate solution containing originally 9% of alpha-cellulose. The yield of MCCh in the resulting fibers was dependent on the molecular mass, and varied between 73–82%. The strength, elongation, and color of the resulting hybrid fibers were only slightly changed and the WRV remarkably increased compared to standard fibers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1725–1730, 2000

Functional hybrid fibers of cellulose/microcrystalline chitosan. I. Manufacture of viscose/microcrystalline chitosan fibers

Blends of microcrystalline chitosan (MCCh) with cellulose xhanthate alkaline solutions were prepared to investigate the effects of aqueous MCCh gel concentration and additives on the spinnability of hybrid cellulose/chitosan fibers and their properties. The properties of the spinning solution were mainly dependent on the concentration of MCCh in the aqueous gel-like dispersion and the amount mixed into the cellulose xhanthate solution. Sodium alginate chemically close to cellulose and chitosan was used as an additive to improve the miscibility of chitosan due to the ionic bonds formed with chitosan 2-amino groups. Using an optimized ratio of 2 : 1 of MCCh to the sodium alginate, a maximum of 6% of MCCh calculated from alpha-cellulose content could be introduced into the sodium xhanthate solution containing originally 9% of alpha-cellulose. The yield of MCCh in the resulting fibers was dependent on the molecular mass, and varied between 73–82%. The strength, elongation, and color of the resulting hybrid fibers were only slightly changed and the WRV remarkably increased compared to standard fibers. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1725–1730, 2000

Ageing phenomena of chitosan and chitosan–diclofenac sodium system detected by low-frequency dielectric spectroscopy

The use of natural polymers for design of dosage form has received considerable attention recently, especially from the safety point of view. Among these polymers, chitosan shows very interesting biological, chemical and physical properties which makes it possible to use chitosan for various pharmaceutical applications. Microcrystalline chitosan (MCCh) is a special multifunctional polymeric material existing in the form of either of gelatinous water dispersion or a powder.Thermal ageing of chitosan and chitosan–diclofenac sodium mixture have been studied using low-frequency dielectric measurements. The ageing was carried out by annealing in ambient atmosphere in the temperature range between 25°C and 100°C. The dielectric losses in the aged samples proved to decrease by about one order of magnitude. The additional measurements of molecular weight distribution and infrared absorption were also carried out for better understanding of nature of the ageing phenomena. Partial evacuation of water, cross-linking and improvement of structural order may be suggested to be a result of thermal ageing of the investigated materials.

Decrease in serum LDL cholesterol with microcrystalline chitosan in healthy subjects

Decrease in serum LDL cholesterol with microcrystalline chitosan in healthy subjects

Decrease in serum LDL cholesterol with microcrystalline chitosan

Peroral microcrystalline chitosan (MCCh; 3 capsules, each 400 mg b.i.d.) or placebo was given for 8 weeks in a double-blind manner to 51 healthy obese women just before routine hospital and home meals. Weight records, serum lipids (total, LDL and HDL cholesterol, triglycerides) and safety laboratory parameters were monitored before the trial and at 4, 6 and 8 weeks of treatment. In a subgroup of subjects with a body mass index > or = 30 who had not changed their eating habits, serum LDL cholesterol decreased 0.57 +/- 0.72 mmol/l (n = ll) at 4 weeks in the MCCh group and 0.10 +/- 0.60 mmol/l (n = 14) in the placebo group (p < 0.05). At 8 weeks, LDL cholesterol reduction was 0.48 +/- 0.91 mmol/l in the MCCh group and 0.26 +/- 0.57 mmol/l in the placebo group (p > 0.1). In all subjects, the reduction in LDL cholesterol at 4 weeks was 0.48 +/- 0.72 mmol/l (n = 24) in MCCh subjects and 0.18 +/- 0.58 mmol/l (n = 27) in placebo subjects (p = 0.057), and 0.52 +/- 0.69 mmol/l and 0.31 +/- 0.63 mmol/l, respectively, at 8 weeks (p > 0.1). MCCh did not significantly alter serum total and HDL cholesterol (p > 0.1), but slightly increased serum triglycerides compared to placebo (p = 0.015-0.06). No reductions in weight were observed in any treatment group. Chitosan was well tolerated and no serious adverse events or changes in safety laboratory parameters were noted including serum fat-soluble vitamins A and E, and serum Fe++ and transferrin.

Percutaneous microcrystalline chitosan application for sealing arterial puncture sites

Arterial catheterization is one of the most frequently performed inpatient diagnostic and therapeutic procedures in the development countries. Complications may occur after any catheterization from inadequate hemostasis, particularly in the setting of aggressive anticoagulation. This study suggests that microcrystalline chitosan (MCCh) sealant installation via an arterial sheath at the completion of catheterization may improve hemostasis. Results using MCCh in eight heparinized dogs documented significant reductions in manual compression time ( P=0.016) of the artery after withdrawal of both the sheath introducer and catheter. Comparative results were found in rats, wherein a created wound in the aorta could be sealed relatively quickly and easily. The biodegradability, optimalization, and a better pharmaceutical formulation of this potential hemostatic agent require further studies.

Nasal delivery of octreotide: Absorption enhancement by particulate carrier systems

The potential of various powder formulations to enhance the nasal absorption of the somatostatin analogue peptide octreotide (Sandostatin ®) was studied by a combination of in vitro and in vivo experiments. The particulate carriers under investigation were microcrystalline cellulose (Avicel PH101), semicrystalline cellulose (Elcema P050), hydroxyethyl starch, cross-linked dextran (Sephadex G25), microcrystalline chitosan, pectin and alginic acid. Determination of the Ca 2+−-binding capacity of these carriers demonstrated large differences for excipients of the same chemical composition, depending on the physical appearance. Whereas Avicel PH101 bound 0.22 μg Ca 2+/mg carrier, no Ca 2+ binding could be detected for Elcema P050. The following rank order was obtained: swollen Sephadex G25 > alginic acid > microcrystalline cellulose = hydroxyethyl starch ⪢ chitosan = pectin = semicrystalline cellulose = 0 For Sephadex G25 a pre-swelling time of at least 30 min was necessary to observe calcium binding (0.55 μg /mg). Determination of water uptake by the different excipients showed a very water uptake of more than 200% (wt/wt) by microcrystalline chitosan and Avicel PH101. The rate and extent of water uptake can be ranked for the nasal particulate carriers as follows: chitosan > microcrystalline cellulose > semicrystalline cellulose ⪢ pectin = hydroxyethyl starch = alginic acid = Sephadex G25. When the absorption of octreotide was determined in vivo in rats after nasal administration together with the respective carrier, the highest bioavailability was seen after coadministration of alginic acid and Sephadex G25 (4,1% and 5.56%). T maxof plasma concentration was between 0.08 and 0.34 min. It was delayed after coadministration of Sephadex G25 and pectin (1 and 2 h), which might be explained by swelling time and gel formation of the excipients. The data suggest a correlation between calcium-binding properties of nasal carriers and their potential as nasal absorption enhancers for peptides under in vivo conditions.

Protolytic and complexing properties of microcrystalline chitosan with Co(II), Zn(II), and Cu(II) ions

AbstractIt has been evidenced that microcrystalline chitosan (MCCh) with a determined (by the potentiometric method in nonaqueous medium) degree of deacetylation of 0.87 acts as a polymeric chelating agent with cobalt(II) and zinc(II). The predomination of hydrolytic reactions, in the case of copper(II) ions, has been attributed to a change in crystalline character of the ligand. The protolytic reactions have been studied using the Katchalsky–Spitnik equation. The pH profiles have been shown for Co(II)–MCCh and Zn(II)–MCCh systems and the corresponding equilibrium constants have been determined as well. Both the amino and hydroxyl groups are involved in Co2+ complexation, whereas for Zn2+, the complexes are formed only via amino nitrogen. © 1995 John Wiley &amp; Sons, Inc.

Enhancement of Metal Ion Sorption Performances of Chitosan: Effect of the Structure on the Diffusion Properties

Chitosan is a well-known sorbent of biological origin for metal ions in diluted effuents. Uptake capacities and sorption rates are restricted by diffusion mechanisms. A grafting of specific functional groups onto a chitosan backbone allows sorption performances to be improved due to the appearance of new sorbing functions and by an improvement in diffusion properties. Scanning electron microscopy coupled with an X-ray energy dispersed analysis demonstrates that an uranium concentration gradient exists in the chitosan polymer but disappears in the glutamate glucan polymer. Chitosan displays a surface controlled sorption mechanism, unlike glutamate glucan in which sorption occurs in the mass of the polymer. Microcrystalline chitosan produced for the sorption of uranyl ions shows diffusion constants comparable to those obtained with glutamate glucan by application of two single models of intraparticular diffusion. This simple technique of modification of the structure of the chitosan allows the uptake capacity and sorption kinetics to be increased. Recrystallization causes chitosan to behave in a way intermediate between raw and substituted forms of chitosan.

Microcrystalline chitosan—Some areas of application

AbstractMicrocrystalline chitosan existing as a new microcrystalline form of standard poly(2‐deoxy‐2‐amino‐D‐glucose) is a special functional polymeric material suitable for several applications. New areas of microcrystalline chitosan use in the textile industry, waste water treatment and medicine are presented. Microcrystalline chitosan in the applications discussed has practical and economic advantages over standard chitosan.

Microcrystalline chitosan. I. Preparation and properties of microcrystalline chitosan

AbstractA new type of microcrystalline polymer prepared by aggregation has been discussed. The effect of the parameters of the preparation process on the properties of microcrystalline chitosan in hydrogel and solid forms has been studied using also microscopy and spectroscopy. The product obtained according to the method discussed shows the average molecular weight within a range 2.2–5.0 X 105, WRVs ≈ 260–520%, WRVg ≈ 700–1000%, and CrI up to 95%.