SILVA, M. C.; http://lattes.cnpq.br/5901180285081828; SILVA, Milena Costa da.
Résumé:
Surgical sutures are biomaterials whose main purpose is to close lesion. Therefore,
they must have adequate mechanical and biological properties for the healing
process to be effective. However, this work aimed at the development of chitosan
threads, optimizing the mechanical / biological properties for application as
biodegradable absorbable sutures. In addition, chitosan yarn has been used as a
controlled release system with N-Acetyl-D-glucosamine (GlcNAc), which, like
chitosan, is a chitin derivative, to combin the pharmacological properties of GlcNAc
with biological properties of Chitosan. Chitosan concentrations of 1, 2, 3 and 4%
were initially characterized from rheological assays, and concentrations of 3 and 4%
(w/v) were chosen because they are more viable for the spinning process. Therefore,
the chitosan strands, coagulated in sodium hydroxide solution, were obtained from
the wet spinning technique, using concentrations of 3 and 4% (w/v) of chitosan. 3
and 4% Optical Microscopy (MO), Scanning Electron Microscopy (SEM), X-ray
Diffraction (XRD), Mechanical Traction Assay, Swelling Degree (GI), In vitro
Biodegradation in Buffered Saline followed phosphate (PBS) PBS/lysozyme assay
and in vitro cytotoxicity. From the morphological tests, it was found that the wires are
cylindrical and well defined. By XRD it was observed that the 4% tensioned wires
presented higher crystallinity, which resulted in higher load resistance, as seen in the
tensile tests. The swelling degree evaluation showed that the 3% (m/v) strands
presented greater swelling, due to the lower degree of crystallinity, that is, the higher
degree of amorphous region in the strand. In the in vitro biodegradation assay, total
degradation was found to occur within 49 days for the 3 and 4% PBS/lysozyme
samples. GlcNAc (0.2 g) was added to 4% chitosan threads, which are within the
Surgical Suture Yarn Standards. The morphological aspect was observed by OM and
SEM, as well as the physicochemical aspects by the Fourier Transform Infrared
Spectroscopy (FTIR) technique. The mechanical properties, contact angle, in vitro
biodegradation and drug release profile, cytotoxicity by agar diffusion method and
wound evaluation in animal wound surgery were also investigated. After the addition
of GlcNAc it was found that the yarn morphology was preserved, but the tensile
strength (N) decreased. However, the values remained within the specifications of
the 6-0 surgical suture standard. It was also found that the biodegradation process
was accelerated in the presence of GlcNAc and its release in 50% occurred in
approximately 34 days. As for release kinetics, the best fit model was Order Zero,
followed by Peppas-Sahlin and Hopfenberg models, controlled by the diffusion and
erosion model, suggesting that GlcNAc is concentration independent, a desirable
situation in the release formulation. sustained as it minimizes fluctuations in the
concentration of drugs in the blood. In vitro cytotoxicity data of 4% chitosan and
chitosan / GlcNAc strands for L929 cells showed that they are not toxic to these cells.
From the clinical evaluation performed on the surgical wound of animals on days 0,
1, 2, 3, 4, 5, 6, 7 and 14 days, it was observed that animals sutured with 4% chitosan
suture / GlcNAc presented closure. complete. wound within 4 days, and the process
of formation of the new tissue began. For chitosan wire, this closure occurred within 7
days. For chrome catgut wire, closure was observed after 14 days. Thus, GlcNAc
chitosan threads are promising for use as an absorbable suture, either for veterinary
use or in human medicine. Additionally, this medical device may be able to improve
healing processes, relieve pain and minimize infection at the surgical site due to
prolonged release of GlcNAc.
