Self-expanding chitosan stents - a technology of fabrication

The possibility of creating a self-expanding stent, consisting of a combination of the saline and the basic form of chitosan has been discussed in the article. The 2 % chitosan solution in 4 % citric acid have been prepared. The spinning solution has been coated onto an inert substrate in a volume of 0.2-0.25 ml/cm2. Chitosan film (saline form) has been obtained by evaporation of the solvent at room temperature under static conditions. Chitosan film thickness has been measured with a micrometer. Samples of chitosan stents have been formed by winding a chitosan film on the plastic tube. The optimal concentration of NaOH and the dwell time for transfer of chitosan in the form of a saline form to basic form have been defined. The stents photos with a hundredfold magnification and AFM-images of the samples surface have been obtained. The estimates of the stent elongation at break (e) (31-46 %) have been evaluated and it has been found that the data on this indicator stents are higher than those obtained from the films form with acetic acid (17 %). These results open up the possibility to create biocompatible biliary stents with their subsequent modification of the active drug substance, which gives hope for improvement of treatment results in patients with obstruction of extrahepatic bile ducts.