Obtention and characterization of scleroglucan films prepared by freeze-thawing cycling

NORA J. FRANÇOIS; SILVANA C. VIÑARTA; MARTA E. DARAIO; LUCIA I.C. FIGUEROA; JULIA I. FARIÑA

Mainz, Alemania

Congreso; Frontiers in polymer science; 2009

This study examines the physical properties of films prepared from scleroglucan hydrogels, which could be suitable for drug delivery purposes. Particularly for biological applications, it is of primary importance that the methods applied for polymer film preparation can keep them free of impurities, such as residual crosslinking drugs. Scleroglucan biopolymer samples from different sources and fermentation times were used in order to obtain the corresponding hydrogels. They were then subjected to a freeze-thawing process with the aim to prepare films with a physically reinforced cross-linked network. Two procedures were employed for obtaining films from scleroglucan hydrogels using glycerol as plasticizer: 1) a room temperature drying method and, 2) a freeze-thawing cyclic process, prior to the application of room temperature drying. Biopolymeric films were subsequently characterized by studies of water vapor transmission, swelling, Environmental Scanning Electron Microscopy (ESEM) and FT-IR spectroscopy. These determinations showed significant differences between films obtained by the two different treatments in the case of a commercial scleroglucan. Films prepared through the freeze-thawing cycling showed a decrease in the swelling degree in a direct relationship to the number of freeze-thawing cycles. The physical differences observed between scleroglucan films prepared according to the two different methods may be explained proposing that the number of crosslinking points by hydrogen bonding increases proportionally to the number of freezing and thawing cycles used for film preparation.