MENEZES, Rafaella Lima de.
Résumé:
Chitin is the second most abundant natural polysaccharide after cellulose It is
biodegradable, non-toxic and found in the marine environment as ordered
crystalline microfibrils forming components in the arthropods exoskeleton and
the cell walls of fungi and bacteria. Properties like biocompatibility,
biodegradability, low toxicity exhibited by chitin fibers combined with adequate
mechanical properties make them candidates for applications such as suture
material. This work aims, obtaining and characterize through a physicochemical
and structural characterization of chitin fibers for their use as sutures, extracted
from the shrimp exoskeletons (species: Litopenaeus vannamei). This research
was divided into two methodologies for a better understanding, is composed by
the chitin extraction process followed by the fiber process obtention. The chitin
concentration used in the fibers formation were 0.5% 0 85% 1%. Dissolved in
DMAc / LiCl2 (5%) solvent and coagulated in ethanol (30%), acetone (70%),
distilled water (100%), CaCl2 (2%). The chitin powder obtained in the first step
of this study was characterized using the X-ray diffraction (XRD) and Fourier
Transform Infrared Spectroscopy (FTIR) techniques. By XRD it was possible to
identify the chitin obtained as alpha chitin, this confirms the chitin structure
present in the shrimp shell, the FTIR revealed the absence of protein,
confirming that the chitin obtained can be used as a biomaterial. The fibers
obtained in the second step of this study were characterized by SEM / EDS,
which revealed the influence of coagulation baths in the fiber diameter, the
increased pH in the coagulation bath led to a more rapid neutralization of the
chitin fibers, a phenomenon known as shrink. Swelling tests revealed the
influence of the coagulation baths, the fibers coagulated with organic solvent,
owned a lower swelling degree compared to the fibers coagulated in aqueous
solvents. For the tensile test the fibers with a chitin concentration of 0.5% due to
a better solution homogeneity had more adequate mechanical properties,
compared to the other fibers produced. The results for cell viability showed a
percentage of 90%, evidencing the solvent absence in the fiber produced.
Through biodegradation tests is possible to observe a mass loss in the fibers
only from the fifth day. The results demonstrated that the objective was achieved, to produce chitin fibers from the shell of shrimps, and indicate a
possible application of this material as a suture wire.
