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Biomedical subjects

R A Muzzarelli

Publications and source records attributed to R A Muzzarelli.

34 records · Page 2Linked to original sources
PubMed1984

Sulfated N-(carboxymethyl)chitosans: novel blood anticoagulants.

N-(Carboxymethyl)chitosan was subjected to sulfation in a mixture of concentrated sulfuric acid (oleum) and N,N-dimethylformamide, under anhydrous conditions. The resulting product contained 11% of sulfur and degree of substitution: N-acetyl, 42%; N-carboxymethyl, 58%; and sulfate, 100%. Sonication of the sulfated N-(carboxymethyl)chitosan gave two main fractions whose molecular weights were 39,000 and 80,000. In human blood, complexes of sulfated N-(carboxymethyl)chitosan and antithrombin inhibited both thrombin and factor Xa, and produced neither hemolysis nor alterations in erythrocytes and lymphocytes. Sulfated N-(carboxymethyl)chitosan is therefore proposed as a blood anticoagulant.

Anticoagulants↗
PubMed1980

Chelating, film-forming, and coagulating ability of the chitosan-glucan complex from Aspergillus niger industrial wastes.

Waste mycelia of Aspergillus niger from a citric acid production plant are simply treated with boiling 30-40% NaOH aqueous solutions for 4-6 hr to obtain the insoluble chitosan-glucan complex whose infrared, ESR, and x-ray diffraction spectra are reported. A number of transition- and post-transition-metal ions are chelated and collected by chitosan-glucan with higher yields than by animal chitosan. Immediate flocculation occurs upon mixing chitosan-glucan dispersions with alginate and polymolybdate solutions. Membranes are also obtained from chitosan-glucan dispersions in acetic acid or in chloral and dimethyl formamide mixtures.

Aspergillus niger↗
PubMed1980

The degree of acetylation of chitins by gas chromatography and infrared spectroscopy.

Gas chromatography of a number of amines, alcohols and sulfur derivatives was carried out on chitin and partially deacetylated chitins as well as on chitosan. The retention time of methanol is proportional to the degree of acetylation, and therefore a method is proposed for the gas-chromatographic determination of the degree of acetylation of chitin/chitosan. The analysis of the infrared spectra of chitin/chitosan also permits one to determine the degree of acetylation by using the ratio of the bands 1550 and 2878 cm-1.

Acetylation↗
PubMed1978

Isolation of lysozyme on chitosan.

Lysozyme has been immobilized on chitosan, a polyaminosaccharide, without using any intermediate reagent. The best pH conditions for operating the chitosan columns have been determined and the best eluting agent was found to be a 2% solution of propylamine. The lysozyme activity was determined after reacting lysozyme with the product of glycolchitin and Remazol Brilliant Blue R. The recovery of lysozyme from chicken egg white yields lysozyme with 55% activity.

Chitin↗
PubMed1977

Chromatographic behaviour of nucleic acid constituents and of phenols on chitosan thin layers.

The chromatographic characteristics of several nucleic acid constituents and of 36 phenols have been investigated on mixed layers of powdered chitosan and microcrystalline cellulose, with water, water-methanol mixtures and aqueous salt solutions at different pH values at mobile phases. The behaviour of the phenols was strongly correlated with the form in which these compounds were present in solution and therefore with the pH of the eluent. Chitosan was more effective than PEI- and DEAE-cellulose as adsorbent in separating phenols. Analytical applications of chitosan layers are reported.

Chemical Phenomena↗
PubMed1976

Immobilized enzymes on chitosan columns: alpha-chymotrypsin and acid phosphatase.

alpha-Chymotrypsin and acid phosphatase have been immobilized on chitosan, a polyaminosaccharide, without using any intermediate reagent; the immobilized enzymes are active and their activity is much higher than for chitin-immobilized enzymes. The best pH conditions for operating chitosan columns have been determined and columns have been used to transform substrates in large amounts, with no decrease of activity or enzyme losses. Due to the nonconvalent interaction between chitosan and enzymes, the pure and active enzymes can be eventually recovered from the columns. The effects of metal ions, aldehydes, and salts are reported and discussed. Applications are foreseen in the food and biomedical sciences and industries.

Acid Phosphatase↗
PubMedDate not supplied

Preparation and characterization of ampicillin loaded methylpyrrolidinone chitosan and chitosan microspheres.

Ampicillin was embedded in microparticles made of a new derivative of chitosan: methylpyrrolidinone chitosan. They were prepared using different drug-to-polymer weight ratios and by a spray-drying technique. Spray-dried drug-loaded chitosan microspheres were prepared for comparison. The microparticles were characterized by scanning electron microscopy (SEM), particle size analysis, differential scanning calorimetry (DSC) and in vitro drug release. Microbiological assay was performed using different bacterial strains. Spray-dried microspheres of almost spherical shape, smooth surface and narrow size distribution were always obtained. Ampicillin loaded into both polymer matrices showed amorphous behaviour as determined by DSC. Drug-loaded microspheres resulted to control the drug release in a 30-120 min range, depending on chitosan type. Thermal denaturation of the microspheres does not modify drug release rate. The results of the microbiological assay show that the loading of ampicillin into chitosans is able to maintain or improve the anti-bacterial activity of the drug.

Ampicillin↗