[Preparation and characterization of novel degradable artificial lacrimal canaliculus]

To develop a novel biodegradable collagen-chitosan-[poly(vinyl alcohol), PVA] composite artificial lacrimal canaliculus for treating tear overflowing (epiphora) caused by canalicular obstruction.

Homo-generously mixing solution composed of collagen, chitosan and PVA with different ratios was prepared. After several cycles of freezing/thawing process, the mixing solution was transferred into elastic hydrogel. Then the hydrogel was rinsed, punctured, dehydrated and trimmed, and three groups (T1, T2 and T3) of novel artificial lacrimal canaliculus were obtained. The appearance and diameter of all samples were observed under optical microscopy. The cross-section before and after drying as well as phase distribution of sample T2 was observed by SEM. The water absorption ratio and expanding ratio in PBS solution were calculated from three swelling behavior curves. The degradability of groups T1, T2 and T3 were preliminary analyzed by degradation experiment in vitro.

The micro-tubes with 0.5-0.7 mm in inner diameter, 0.9-1.5 mm in outer diameter and more than 20 mm in length were fabricated successfully through physical crosslinking without addition of toxic cross-linker. SEM result showed that the sample had uniform phase distribution and smooth surface at dried state as well as interpenetrate network structure at hydrogel state. It was seen from the swelling behavior curves that groups T1, T2 and T3 swelled rapidly within 10-30 minutes, and formed elastic composite hydrogel pipes. In addition, the expanding ratio of inner and outer diameter of the tube was 20%-30% and 100%-120% with swelling, respectively. The equilibrium water content of the hydrogel pipes increased with increase of collagen composition. Three groups of samples were immersed in PBS solution contained 2 mg/mL lysozyme at 37 degrees C for 1 month, their nozzle cracked, their wall became thin and more transparent. And also, there was small floc deposited on the tube surface. The samples were degraded into mash after they were soaked in PBS solution at 70 degrees C for 2 days.

The novel artificial lacrimal canaliculus with good mechanical property and high water absorption is in favor of operation, tear passing and anti-conglutination. It will be a potential candidate for treating the lacrimal passage occlusion.