Preparation and Characterization of Na-Alginate Hydrogel Beads

Abstract

A series of Na Alginate (Na-Alg) hydrogel beads were prepared by usingionic cross linking method. The beads were obtained by dropping of Na-Algsolution in chilled oil bath at -18 ºC first and then leaving the hardenedbeads into the cross linker solution. CaCl2 solution was used for ionic crosslinking of Na-Alg molecules. While the concentration of Na-Alg solution waskept constant, crosslinking time was changed from 5 to 30 minutes. In general,longer crosslinking times negatively affect hydrogel formation. Swellingbehaviors of the hydrogels were studied by changing time, temperature and pH.The higher crosslinker / polymer rates caused lower swelling values. It wasdetermined that the swelling percentages regularly decreased with increasingthe crossliking time. While the time increased from 5 to 30 minute, swellingpercentages decreased from 158 % to 33 %. Temperature changing negligiblyaffects the swelling percentages. The prepared Na-Alg  hydrogels could not be commended astemperature sensitive.