The effect of chitosan hydrolysate on the fungi alternaria solani, fusarium solani and rhizoctonia solani in vitro

Chitosan hydrolysate was obtained using nitric acid; the prevailing fraction had a molecular weight of 30 kDa and a deacetylation degree of 95%. The effect of chitosan hydrolysate when added to potato dextrose agar (PDA) in different concentrations (0.5, 1, 1.5, 2, 4, 6 and 8 mg/mL) was studied on the growth of the fungi Alternaria solani Sorauer, Fusarium solani (Mart.) Sacc. and Rhizoctonia solani J.G. Kühn. A. solani was the most sensitive to the addition of chitosan hydrolysate to PDA in radial growth experiments. On days 3 and 7 of incubation, the antifungal activity of the phytopathogen growth was 69%-92% and 69%-88%, respectively, in the concentration range of 0.5-2 mg/ml

The formation of hydrogels based on chitosan and its water-soluble derivatives

This review considers articles on the formation of hydrogels based on chitosan as well as succinylated and quaternized chitosan derivatives. They are synthesized using low toxicity reagents, under ordinary conditions (low production costs). Chitosan derivatives are soluble in an extended range of pH values and characterized by mucoadhesiveness, bioavailability and biodegradability, which extends the potential of their medical applications. One of the most important properties of chitosan and its derivatives is the ability to form hydrogels. Depending on the nature of the bonds that occur during formation, hydrogels are divided into chemically or physically crosslinked, or a mixture of the two. Chemically crosslinked gels have covalent bonds, while physically crosslinked gels are formed by noncovalent interactions, for example, ionic. Mixed hydrogels have both types of crosslinking

The inhibition of human platelet aggregation by a low-molecular weight chitosan

Chitosan derivatives were obtained by chemical (MW of 6 kDa, DD 99% - Ch6/99; MW13 kDa, DD 98% - Ch13/98) and enzymatic (MW of 5 kDa, DD 85% - Ch5/85; MW of 10 kDa, DD 85% - Ch10/85) depolymeri-sation of chitosan with a MW of 334 and 1000 kDa. Chitosan derivatives (almost identical MW pairs and different DD) possessed insignificant an-ticoagulant activity, did not promote human platelet aggregation and re-duced ADP or collagen-induced platelet aggregation. The studied sam-ples at a concentration of 2 mg/ml reduced the aggregation of platelets more than twice induced in 2x10-6M and 1x10-5M concentrations; at weak activation in 2x10-6M, the Ch10/85 sample was the most effective. The Ch6/99 and Ch13/98 samples were 20 times more effective at the inhibi-tion of collagen-induced platelet aggregation than the Ch10/85 sample. The latter can be explained by the greater value of positive charge (DD) and polydispersity (Mw/Mn) of chitosan samples obtained by chemical de-polymerisatio

Thromboresistant silicon plates modified with chitosan and heparin by the layer-by-layer assembly method

Fifteen samples of silicone plates (PlateSi, area=12 cm2), with surfaces modified layer-by-layer with chitosan and unfractionated heparin, were obtained. The sample surfaces were pre-treated by cold oxygen plasma in a planar-type plasma chemical reactor with 50 W power before coating with layered polysaccharides. Pre-treatment was carried out in two alternative operation modes of the reactor, namely in the plasma etching mode and in the reactive-ion etching mode. Thromboresistance was assessed in vitro in contact with human blood. The thromboresistant silicon plates, modified layer-by-layer (3, 5, 7, and 9 bilayers) with chitosan, with molecular weights of 65 kDa, increased with the increase in the number of layers, up to 5. An increase in the duration of thromboresistance was observed in layer-by-layer modification of the surface of the plates with chitosan with a molecular weight of 200 kDa or with quaternized chitosan with a molecular weight of 200 kDa. Some samples of highly thromboresistant, modified PlateSi contributed to the adhesion of platelets and the haemolysis of red blood cells to a lesser extent than untreated silicon plates. The three most promising samples of modified PlateSi were selected