3858 results about "Hydroxyethyl cellulose" patented technology

A composition for controlled delivery of at least one active substance into an aqueous medium by erosion at a preprogrammed rate of at least one surface of the composition, comprising a matrix comprising the active substance, the matrix being erodible in the aqueous medium in which the composition is to be used, and a coating having at least one opening exposing at least one surface of said matrix, the coating comprising a first cellulose derivative which has thermoplastic properties and which is substantially insoluble in the aqueous medium in which the composition is to be used, and at least one of a second cellulose derivative which is soluble or dispersible in water, a plasticizer, and a filler. The coating is a coating which crumbles and / or erodes upon exposure to the aqueous medium such as a body fluid. The first cellulose derivative may be, e.g., ethylcellulose, cellulose acetate, cellulose propionate or cellulose nitrate, and the second cellulose derivative may be, e.g. methylcellulose, carboxymethylcellulose or salts thereof, cellulose acetate phthalate, microcrystalline cellulose, ethylhydroxyethylcellulose, ethylmethylcellulose, hydroxyethylcellulose, hydroxyethylmethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxymethylcellulose or hydroxymethylpropylcellulose.

The present invention provides compositions and methods for tissue repair using a cytocompatible self-gelling cross-linked hydrogel. The composition comprises a biocompatible mixture of chitosan, bifunctional dialdehyde, and hydroxylated polymer, which can be used to immobilize or encapsulate viable cells, or bioactive substances. The method includes the process of mixing bioactive substances, live cells, and / or extracellular matrix components with a cross-linking solution comprising a bifunctional aldehyde-treated hydroxylated polymer such as hydroxyethyl cellulose. The cross-linking solution is then mixed homogenously with a neutral isotonic chitosan solution. The chitosan becomes cross-linked by the bifunctional aldehyde, while the cells are protected from potentially nocive effects of the aldehyde cross-linker by the hydroxylated polymer. The injectable solution retains cell viability and bioactivity, and immobilizes cells at the site of injection or delivery. Depending on the particular application, mixtures of chitosan and bifunctional dialdehyde may be employed. The injectable solution also liberates bioactive substances with controlled release kinetics from the site of injection.