Browsing by Author "Kamburov M."

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    Daunorubicin-loaded chitosan microparticles - preparation and physicochemical characterization
    (2016-01-01) Kamburov M.; Simeonova M.
    The present study deals with the preparation and characterization of chitosan microparticles as a drug delivery system for daunorubicin. The microparticles are prepared by the suspension method and their properties are improved by covalent crosslinking using glutaraldehyde. The obtained spherical microparticles with size of 300 μm are loaded with daunorubicin. The ?orphology and chemical composition of the microparticles obtained are investigated by scanning electron microscopy and FTIR. The effect of the crosslinking and the amount of the encapsulated drug on the in vitro release kinetics is investigated by VIS spectroscopy. The release rate of daunorubicin (physically entrapped) is controlled by the degree of swelling of the microparticles hydrogel matrix. The release rate of the covalently bounded daunorubicin from chitosan microparticles in simulated intestinal fluids containing lysozyme depends on the density of crosslinking. It is found that slower drug release rates are obtained from highly crosslinked microparticles. These results indicate that chitosan microparticles have a potential as a drug delivery system for oral administration because they provide controlled release with the participation of the lysozyme enzymes in the digestive tract.
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    Deinging of recycled paper with offset printing through flotation and use of enzymes
    (2013-11-05) Lasheva V.; Ilieva B.; Kotlarova S.; Kamburov M.
    Use of recycled fiber material for the production of paper and paperboard has a significant share in solving problems related to environmental protection and conservation of energy resources. One of the most important processes for the paper recycling with printing press is a deinking. Perspective method for deinking of waste paper by the method of flotation is the enzyme treatment at neutral pH. The aim of this work is to study the deinking of recycled paper with offset printing press through flotation and use of enzymes.
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    Preparation of chitosan beads for trypsin immobilization
    (2014-04-16) Kamburov M.; Lalov I.
    The present study deals with the potential application of chitosan macrobeads for immobilization of trypsin. Macrobeads were prepared by precipitation and their mechanical properties were improved by covalent crosslinking using glutaraldehyde. Scanning electron microscopy studies showed that the beads size varied between 2.5 mm and 3.5 mm depending on the chitosan content and molar excess of glutaraldehyde. Trypsin (EC.3.4.21.4) was chosen as model enzyme for immobilization on the chitosan gel beads pre-activated with glutaraldehyde. Catalytic properties and kinetic parameters of free and immobilized trypsin were determined and the impact of various technological parameters on enzyme activity was investigated. The obtained results showed that the optimal pH and temperature for the hydrolytic reaction catalyzed by immobilized trypsin for low molecular weight substrates were pH 8.0 and 50oC, respectively. The effect of substrate concentration was also studied and the values of the constants thus determined were: Km=1,54 mM/L and Vmax – 3.3 μM/min.