2D Bi-layer scaffolds of polycaprolactone and chitosan β-glycerol-based film for blood vessel constructs

Methods: Several polymeric adsorber membranes and ceramic membranes were investigated concerning their endotoxin removal ability. Therefore mem- branes were loaded with aqueous endotoxin solutions (0-1000 EU/mL) and tested in cross-flow and dead-end modus. The permeat samples were analyzed by the Limulus Amoebocyte lysate (LAL) test. The endotoxin removal of a mem- brane was classified as sufficient at permeat endotoxin levels under 0.25 EU/ mL. For microscopic analysis the membranes were loaded with fluorescence- labeled endotoxin, embedded and analyzed via fluorescence microscopy. Results: Although adsorber membranes showed good endotoxin binding ca- pabilities the endotoxin removal was insufficient. Ceramic membranes showed significant better endotoxin separation. Microscopic analysis showed that in polymeric membranes endotoxin could penetrate until a depth of 25μm, where- as in ceramic membranes the penetration depth was only 4μm. Conclusions: Microscopic analysis of endotoxin filtration gives a deeper un- derstanding in the separation behavior of the investigated membranes. Further fouling and capacity of the membranes can be observed directly. In the future a quantitative correlation of the endotoxin amount on the membranes should be established by measuring the fluorescence intensity of the labeled endotoxin.